AMCCR: Adaptive Multi-QoS Cross-Layer Cooperative Routing ...downloads.hindawi.com/journals/jcnc/2017/3638920.pdf · ResearchArticle AMCCR: Adaptive Multi-QoS Cross-Layer Cooperative

Research ArticleAMCCR Adaptive Multi-QoS Cross-Layer CooperativeRouting in Ad Hoc Networks

Mahadev A Gawas1 Lucy J Gudino1 and K R Anupama2

1Department of Computer Science and Information System BITS-Pilani K K Birla Goa Campus Goa India2Department of Elecrical Electronics and Instrumentation Engineering BITS-Pilani K K Birla Goa Campus Goa India

Correspondence should be addressed to Mahadev A Gawas mahadevgoabits-pilaniacin

Received 7 February 2017 Accepted 12 July 2017 Published 2 October 2017

Academic Editor Liansheng Tan

Copyright copy 2017 Mahadev A Gawas et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The cooperative communication technique in an ad hoc network exploits the spatial diversity gains inherent in multiuser systemsand mitigates the multipath fading This technique is necessary but perhaps not sufficient to meet the QoS demands in ad hocnetworkThis is due to the fact that routing protocol at the network layer is more responsible for the successful packet delivery andQoS support In this paper we propose an adaptivemulti-QoS cross-layer cooperative routing (AMCCR) protocol that enhances theperformance through the cooperation of physical MAC and network layers We first formulate an approach to analyze the channelstate variations for effective communication schemes at the physical layer Secondly we dynamically select the transmission modeto employ cooperative MAC scheme by exploiting spatial diversity Thereafter the network layer chooses an optimized route fromsource to destination through the selected best relay candidates based on multiple QoS metrics The paper is further extendedto support dual-hop half-duplex communication via selected relay by coding technique The proposed protocol is validated byextensive simulations and compared with CD-MAC and CODE protocols The results clearly show that the proposed cooperativecross-layer design approach significantly improves the average delay throughput and network lifetime of the system

1 Introduction

The wireless ad hoc network has gained immense popularitydue to the ubiquity of portable mobile devices and the con-venience of infrastructure-less communication Today thesignificant advances in wireless communication have broughta revolution in the area of mobile communication With theincreasing time-sensitive multimedia traffic on the Internetthere is a demand to set QoS features to meet the rigorousperformance demands [1 2] The QoS is defined as a set ofconstraints such as end-to-end delay throughput packet lossand energy which need to be satisfied by the network

In wireless communications errors in data transmissionsoccur due to the unreliability of wireless channel caused bythe nodersquos mobility energy exhaustion and channel fadingThis consequently leads to retransmission when erroneousdata frames are detected which further results in an increasein delay and decrease in the packet delivery ratio of the net-work Thus achieving multiobjective QoS in ad hoc network

is challenging These circumstances motivate the innovationof a new technology known as cooperative communication(CC) [3 4]

Recently cooperative communication has received con-siderable interest of research fraternity in wireless networksThe idea of cooperative communications has been mainlyconcentrated on the physical layer with the advances in thetechniques such as modulation and coding to allow nodesto cooperate in their transmissions to improve the overallperformance of the wireless networks [5] The cooperativecommunication at the physical layer comprises decision-making in selecting cooperative relaying schemes like storeand forward amplify-and-forward [6] and decode-and-forward [7] choosing power for signal transmission andselecting scheme for relay selection

The innovation of cooperative communication is notrestricted to the physical layer only To subjugate the constantnode mobility it would be ideal to expose the physical layerinformation for the cooperation to different higher protocol

HindawiJournal of Computer Networks and CommunicationsVolume 2017 Article ID 3638920 18 pageshttpsdoiorg10115520173638920

2 Journal of Computer Networks and Communications

layers In the recent time the cooperative MAC scheme inad hoc wireless networks has also attracted much attention[8]These schemes use handshaking techniques to reserve thechannel and avoid the collision problemsThese schemes usecross-layer design between the physical and MAC layers forrelay selection with the criteria related to rate adaptation andpower control Due to random nature of the wireless channelMAC layer should know when to initiate the cooperativetransmission Thus the cooperative MAC should utilize theassistance from a relay node to forward the data using betterlink adaptation techniques and higher data rates to enhancethe network throughput

Usage of cooperative communication together with rateadaptation techniques can enable the nodes to adapt theirdata rates tomatch the channel conditions and nodemobilityCombining both these techniques can provide a substantialthroughput improvement in direct and conventional multi-hop network

In this paper we establish cooperation between physicalMAC and network layers We propose an effective dis-tributed cross-layer cooperative routing algorithm formobilenodes by using multi-QoS cooperative metrics that use thepotential cooperation gain to find the optimal route Thecross-layer coordination between the MAC and networklayers is used to select an optimal next hop while the cross-layer coordination between the MAC and physical layers isused to select the best relay

The main objectives of the proposed algorithm are asfollows

(1) An energy-aware end-to-end delay efficient routediscovery scheme is proposed among the networknodes in order to increase the network lifetime

(2) Using the channel state information at the physicallayer the proposed algorithm determines whethercooperation on the link is necessary or not

(3) In case the cooperation on the link is necessarymulti-QoS metric is used to determine the potential relaynodes for a cooperative transmission over each linkThe cooperative mode activation is implemented inthe MAC layer

(4) We exploit the cross-layer approach to the routinglayer for relay selections and resource allocationsthat reflect the potential cooperation gain to find theoptimal paths The best relay node selection strategyis executed in distributed manner

(5) The proposed algorithm is analyzed with single relayparticipation for cooperative scheme and furtherextended for supporting network coding scheme

(6) The best relay selection is enabled with collisionavoidance mechanism

The rest of the paper is organized as follows Section 2discusses the related work In Section 3 we describe thephysical model and assumptions Section 4 describes ouradaptive cooperative cross-layer architecture In Section 5we propose our cooperative network coding technique TheNAV is analyzed in Section 6 Performance evaluation andconclusions are presented in Sections 7 and 8 respectively

2 Related Work

In the recent time the cooperative MAC schemes in adhoc wireless networks have attracted much attention Theseschemes use handshaking techniques to reserve the channeland avoid the collision problems These schemes uses cross-layer design between the physical and MAC layers for relayselection with the criteria related to rate adaptation andpower control

Sai Shankar et al proposed a protocol called CMAC[9] with minor modifications to the standard IEEE 80211Distributed Coordination Function (DCF) When the sourcenode sends the data packets and if destination node receivesthem with errors or fails to receive them the source nodeselects a cooperative relay node to forward the lost datapacket Although CMAC provides the reliability of datatransmission and throughput enhancement it assumes thatthe link between any nodes is ideal and error-free The relay-enabled DCF (rDCF) [10] and cooperative MAC (Coop-MAC) [11] were proposed to exploit the multirate capabilityand counter the throughput bottleneck caused by the lowdatarate linksTheCoopMACand rDCFprotocols choose to sendpackets at a high data rate using relay node in a two-hopman-ner instead of a low data rate with direct transmission andimprove the network performance In rDCF the best relaynode is selected by the receiver based on the piggybackedinformation in the control frame Meanwhile in CoopMACthe relay node itself decides whether to cooperate or notbased on its local information maintained in the cooperativetable Both protocols are not suitable for multihop ad hocnetworks and do not have any provision to deal with hiddennode and exposed node In UtdMAC [12] data packets aretransmitted through the relay whenever a direct transmissionfails due to fading But in UtdMAC it is assumed that therelay is selected a priori and will be ready to transmit in acooperative method whenever necessary Thus this protocoldoes not have to deal with much of the relay selection over-head andmanagementThe cooperative diversity MAC (CD-MAC) proposed by [13] is based on the DCF mode In CD-MAC nodes use Distributed Space-Time Coding (DSTC)In CD-MAC the transmission of multiple copies of a datastream is distributed among the cooperating nodes which actas a virtual antenna array The cooperating nodes encode thedata by using orthogonal codes and simultaneously transmitit to the destination The packet scheduling technique CD-MAC is similar to that of ARQ scheme where cooperationis triggered when a direct transmission of a control packetfails A source node sends an RTS packet to the destinationnode If the destination replies with a CTS before the timeoutperiod expires then CD-MAC does not initiate cooperationelse it activates the cooperation in the next phase Thesource node intimates the need for cooperation to relay nodesthrough repeated RTS (C-RTS) packet The destination nodereplies to a C-RTS with C-CTS simultaneously to relay andsource node During cooperation using DSTC source nodefirst sends a packet to the relay in the first phase and thenboth the source and relay simultaneously transmit the codedpacket to the destination node In CD-MAC each nodemaintains an estimate of neighbor nodes link quality through

Journal of Computer Networks and Communications 3

periodic broadcast ofHello packetsHowever due to repeatedtransmission of control packets the nodes suffer in termsof end-to-end latency CD-MAC does not handle the issueeffectively in case the relay node is unavailable Also theenergy consumption is not addressed properly hence dueto repeated control packet transmissions the latency getsincreased this further results in higher energy consumptionfor CD-MAC

In the traditional layering network protocol architecturethe strict boundary between the layers ensures the easydeploying of network but the encapsulation of the layersprevents sharing of certain vital information between layersTraditional routing protocol optimizes each of the threelayers namely physical MAC and network layers indepen-dently which may contribute to suboptimal network designs[14]The traditional ad hoc routing protocols are designed forpoint-to-point communication which do not take advantageof the cooperative diversity technique [6 15]

Recently there has been an increased interest in proto-cols for mobile ad hoc networks to exploit the significantinteractions between various layers of the protocol stack forperformance enhancements [16]The research at the physicallayer and MAC layer can be combined with higher layersin particular the routing layer to realize a fully cooperativenetwork [17] However the problem of combining routingwith cooperative diversity has received very little attention

In some of the proposed researches towards cooperativerouting the primary objective of the routing is focusedon energy efficiency [18] reduced collisions [19] enhancedthroughput [20] outage probability [21] and so forth Mostof these cooperative routing algorithms are designed with thespecific demand of requirements on single QoS parameter fora particular application Hence it is difficult tomake compre-hensive cooperative routing satisfying the needs of all appli-cations Further significant effort has not been done in QoSprovisioning for cooperative routing in wireless networksespecially in the context of achieving multiobjective QoSservices namely end-to-end delay reliability throughputand network lifetime The existing cooperation techniquesmentioned above do not consider cross-layer coordinationbetween physical layer MAC layer and network layer

3 System Model

Consider the mobile wireless ad hoc network comprisingnodes 119881119894 119881119894+1 119881119899 These nodes transmit a signal toneighbor nodes directly or may employ one relay nodeamong the neighborhoodWe consider the IEEE 80211g PHYlayer which uses different modulation techniques to supportmultiple data rates of 6 9 12 18 24 36 48 and 54Mbps [10]All the control packets and headers namely RTS CTS PHYand MAC headers are transmitted at a fixed rate of 1Mbs

In our experiments we consider only one relay nodeselection in each hop in order to control complexity andthe interference from simultaneous transmissions Let 119877119894represent the relay node in the 119894th hop thus the set of 119873relays is denoted by 119877119894 119877119894+1 119877119899 The system considersslow Rayleigh fading channel model Each node is equippedwith single antenna imposed with half-duplex constraint

with the impracticality of concurrent radio transmission andreception

Let ℎ119881119894 119881119894+1 ℎ119881119894 119877119894 and ℎ119877119894 119881119894+1 represent the channel gainfrom the node119881119894 to the next hop119881119894+1 fromnode119881119894 to relay119877119894and from relay 119877119894 to node 119881119894+1 respectively Statistically theyaremodeled as independent and identically distributed (iid)circularly symmetric complex Gaussian random variablewith zero mean and equal variance 1205902119881119894 119881119894+1 1205902119881119894 119877119894 and 1205902119877119894 119881119894+1 respectivelyThe noises 120578119881119894 119881119894+1 and 120578119877119894 119881119894+1 aremodeled as zeromean complex Gaussian random variables with variance1198730

We model the cooperation approach in two phases Inphase 1 the source node 119881119894 broadcasts its information to thenext hop 119881119894+1 which is overheard by neighbor 119877119894 nodes Thesignal received at the next hop and the neighbor relay arerepresented as 119910119881119894 119881119894+1 and 119910119881119894 119877119894 respectively

119910119881119894 119881119894+1 = radic1198751ℎ119881119894 119881119894+1119909 + 120578119881119894 119881119894+1119910119881119894 119877119894 = radic1198751ℎ119881119894 119877119894119909 + 120578119881119894 119877119894 (1)

where 1198751 is the power transmitted at the node 119881119894 and 119909 rep-resents the transmitted information symbol In phase 2 theneighbor node 119877119894 processes the received signal by amplify-and-forward (AF) or decode-and-forward (DF) techniquesdepending on the following specified criteria

(1) For adaptive cooperation with amplify-and-forward(AF) technique in phase 2 under the AF techniqueimplementation the selected relay terminal simplyamplifies the received signal and forwards it to thenext hopwith transmission power1198752 As stated in [6]under AF technique the achievable rate between 119881119894and 119881119894+1 with 119877119894 is given as

119862AF = 119882 sdot 119868AF (119881119894 119881119894+1 119877119894) (2)

where 119882 represents the bandwidth of channels atnode 119881119894 and relay 119877119894 and the average mutual infor-mation 119868AF(119881119894 119881119894+1 119877119894) between the input and theoutputs achieved by iid complex Gaussian inputs isgiven by

119868AF (119881119894 119881119894+1 119877119894)= log2 (1 + SNR119881119894 119881119894+1 + SNR119881119894 119877119894 sdot SNR119877119894 119881119894+1

SNR119881119894 119877119894 + SNR119877119894 119881119894+1 + 1)SNR119881119894 119881119894+1 = 11987511205902119881119894 119881119894+1

10038161003816100381610038161003816ℎ119881119894 119881119894+1 100381610038161003816100381610038162SNR119881119894 119877119894 = 11987511205902119881119894 119877119894

10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162SNR119877119894 119881119894+1 = 11987521205902119877119894 119881119894+1

10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162

(3)

The signal received at the next hop is represented as

119910119877119894 119881119894+1 = radic11987511198752radic1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730

ℎ119877119894 119881119894+1ℎ119881119894 119877119894119909 + 1205781015840119877119894 119881119894+1 (4)


where

1205781015840119877119894 119881119894+1 = radic1198752radic1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730

ℎ119877119894 119881119894+1120578119881119894 119877119894 + 120578119877119894 119881119894+1 (5)

120578119881119894 119877119894 and 120578119877119894 119881119894+1 are assumed to be independentThus1205781015840119877119894 119881119894+1 is modeled as a zero mean complex Gaussianrandom variable with a variance

( 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730 + 1)1198730 (6)

The next hop node on receiving the signal from therelay and previous hop node detects the symbolstransmitted with the knowledge of the channel gainsℎ119881119894 119881119894+1 and ℎ119877119894 119881119894+1 respectively The next hop nodeimplements a Maximum Ratio Combiner (MRC)technique [22] to decode the signals received fromthe previous hop node and the relay node The MRCoutput at the next hop is given as

119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (7)

where 1198861 and 1198862 are given as

1198861 = radic1198751ℎlowast119881119894 119881119894+11198730

1198862 = radic(11987511198752 (1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730)) ℎlowast119881119894 119877119894ℎlowast119877119894 119881119894+1(1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162 (1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730) + 1)1198730

(8)

where ℎlowast is the conjugated channel gain correspond-ing to the received symbol Assuming that the averageenergy of transmitted symbol 119909 in (1) is 1 the SNR ofMRC output is represented as

120574 = 1205741 + 1205742 (9)


1205741 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 1003816100381610038161003816100381621198730 1205742 = 11198730

11987511198752 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162 + 1198730 (10)

(2) For adaptive cooperation with decode-and-forward(DF) technique in phase 2 to implement the tech-nique if the selected relay terminal is able to decodethe symbols of the received information from theforwarding node 119881119894 correctly then it retransmits theinformation with power 1198752 to the next hop Weassume that if the SNR received at the relay is greater

than the threshold then the symbol will be correctlydecoded As stated in [6] under DF technique theachievable rate119862DF between119881119894 and119881119894+1 via119877119894 is givenas

119862DF = 119882 sdot 119868DF (119881119894 119877119894 119881119894+1) (11)

where average mutual information 119868AF(119881119894 119877119894 119881119894+1)between the input and the outputs achieved by iidcomplex Gaussian inputs is given by

119868DF (119881119894 119877119894 119881119894+1) = min log2 (1 + SNR119881119894 119877119894) log2 (1 + SNR119881119894 119881119894+1 + SNR119877119894 119881119894+1) (12)

The signal received at the next hop node is given as

119910119903119889 = radic1198752ℎ119877119894 119881119894+1119909 + 120578119877119894 119881119894+1 (13)

The channel gains ℎ119881119894 119881119894+1 ℎ119877119894 119881119894+1 and ℎ119881119894 119877119894 are assumedto be known at the receiver but not at the transmitterand are assumed to be independent of each other Thenext hop 119881119894+1 on receiving the signal from the relay andprevious forwarding node detects the symbols transmittedwith the knowledge of the channel gains ℎ119881119894 119881119894+1 and ℎ119877119894 119881119894+1 respectively The next hop implements a MRC The MRCmaximizes the SNR at the receiver so that the bit errorrate is minimized The combined signal at the next hop isrepresented as

119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (14)

where 1198861 and 1198862 are computed to maximize the SNR of MRCoutput at the next hop node and are represented as

1198861 = radic1198751ℎ119881119894 119881119894+11198730 1198862 = radic1198752ℎ119877119894 119881119894+11198730

(15)

Assuming that the average energy of transmitted symbol 119909 in(1) is 1 the SNR of MRC output is represented as

120574 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198730 (16)

4 AMCCR Cross-Layer Architecture

In this section we propose AMCCR cross-layer schemewhich uses an energy-efficient QoS routing to meet therequirements of the application We also propose using theadaptive MAC to identify the relay nodes satisfying certainQoS metrics to cooperate the data transmission with theintermediate hops in the path discovered in routing phase


41 Energy-Aware QoS Routing The QoS routing is anessential component of a AMCCR architecture The QoSfactor aims at improving the quality of service in the wirelesscommunication The wireless ad hoc networks are power-constrained as the nodes have limited battery energy There-fore the energy of the node is a crucial QoS factor in thedesign of the routing algorithm [23] We propose an energy-efficient routing scheme for the wireless ad hoc networksin order to increase the network lifetime while forwardingthe packets through energy-constrained nodes The energyefficiency can bemeasured by the time for which the networkcan maintain a desired performance level called networklifetime The minimum energy routing is different from therouting to maximize the network lifetime as sometimesminimum energy routing invites more flows in an areaand the nodes in the route are exhausted very early Thusthe entire network cannot perform due to failure of thesenodes Hence it is vital to route the packets in a network bybalancing the lifetime of all the nodes so that desired networkperformance can be achieved for a long time Hence energyefficiency is not only measured by the power consumptionbutmore generally it can bemeasured by the duration of timeover which the network can maintain a certain performancelevel

In the proposed QoS routing scheme we use AODV [15]as a routing algorithm with minimal modifications Whena source node has data to send to the destination node itfloods with the route request packet RREQ to its neighborsThe ⟨source-address broadcast-id⟩ pair is used to identify theRREQ uniquely to control the overhead created by floodingand reducing the transmission of repeated information Inthe proposed routing scheme the source incorporates aminimum required node energy threshold value 119864thresh andminimum residual energy of the node 119864residualThe hop countand reserved field in RREQ frame are replaced with 119864threshand 119864residual respectively Thus no additional overhead formodifications is needed in the RREQ frame structure The119864residual field is initialized to zero by the source

On receiving the RREQ node checks if its residual energyis higher than the 119864thresh value specified in the frame Iftrue then it updates 119864residual field of RREQ with its own119864residual value and rebroadcasts the RREQ to its neighbors Anintermediate node can collect multiple RREQ copies for thepredetermined time duration RREQwait which is assumed as20ms The intermediate node retains the RREQ with highest119864residual value and processes further The destination nodereplies to source using the pathwith the highest119864residual valueThus the scheme ensures that the path discovered does notconsist of energy acute nodes

42 Cooperative MAC To optimize the performance weexploit the MAC cooperation while selecting the route fromsource to destination Once the route from the source 119881119894to the destination 119881119895 is discovered any two adjacent nodescan select a relay node for cooperation to meet certainQoS requirements Consider the example shown in Figure 1where path is discovered between 119881119894 and the destination 119881119895Any two adjacent nodes like119881119894 and119881119894+1 in the path can selectandutilize the relay node119877119894 which is in the interference range

R1 R2 Rn

R3

Vi Vi+1 Vi+2 Vj

Figure 1 Multihop cooperative routing path

of both these nodes for cooperative transmission as shown inFigure 1

For each hop on the routing path determining the needof relay node 119877119894 between two adjacent nodes and selectingthe optimal one from them are challenging To address thisproblem we propose an adaptive cooperative MAC Theprimary focus of cooperative setup in the MAC layer is tometiculously allocate the resources and to engage cooperativenodes in setting up the cooperative environment

The nodes willing to communicate over the 80211 net-work use four-way handshake procedure to eliminate thehidden terminal issue The communication between nodesis initiated by exchanging RTSCTS packets We assume thatthe link is symmetric The node 119881119894 transmits the RTS alongwith the payload of length 119871 The receiving node 119881119894+1 basedon SNR of received RTS signal computes the bit error rate(BER) and selects the appropriate data rate DR119881119894-119881119894+1 fortransmission from the node 119881119894 The broadcast nature of thewireless channel allows neighboring nodes of the sender 119881119894to overhear the RTS and determine the appropriate data rateDR119881119894-119877119894 between the transmitter and themselves based on theestimated SNR and BER The receiving node 119881119894+1 transmitsCTS incorporating DR119881119894-119881119894+1 to node 119881119894 The neighboringnode to qualify as relay node checks channel allocationfor any ongoing communication in the interference regionthrough network allocation vectors (NAV) to alleviate hiddenterminal problems If NAV is not set it decodes the CTStransmitted from the node 119881119894+1 and selects the appropriatedata rate DR119877119894-119881119894+1 based on receiving signal SNR value

43 Best Relay Selection Criteria To participate in cooper-ative communication between transmitter 119881119894 and receivernode 119881119894+1 as relay node neighbor node goes through cer-tain QoS metric The selection of good-quality relay nodesis essential to achieve the objectives such as energy effi-ciency and high throughput which enhances the systemrsquosperformance In the existing schemes the relay selectionmechanism mostly incurs extra overhead for complicatedinteractions among the neighbor links Thus it is essentialto analyze the impact of complicated interactions amongthe neighbor links on cooperative diversity performance andminimize it to the lowest possible In MANETs there mightbe several neighbor nodes willing to join the transmittingnode in cooperation communication and selecting the opti-mal one from them is challenging If every neighbor nodestarts transmitting the request to the source it will lead towastage of bandwidth and energy of the nodes which may


further incur additional delay So to deal with such cases weprimarily focus on certain effective criteria for relay selectiondescribed as follows

(1) Distributed relay selection in some of the schemessuch as centralized relay selection technique [24] therelay selection is done in a passive listeningmodewithcentralized control In this technique all the neighborrelayrsquos channel state information (CSI) is accumulatedand compared which induces complexity and delayThe scheme proposed in [11] requires periodic broad-cast of readiness message by each neighbor node toits one-hop neighbors irrespective of whether thecooperative mode is needed or not

(2) Adaptive relay selection in fixed relaying schemedata transmission always happens via relay node evenwhen the destination node can directly receive anddecode the data packets transmitted from the sourceHence time slot used by the relay to forward thedata packets is a waste of resources and takes doublethe time to transmit packets compared to the directtransmission To counter these problems adaptiverelay selection would be more recommendable

(3) Optimal number of relays to improve the networkperformance many researchers [24] proposed usingmultiple relay nodes with the intent of increasingthe diversity gain However the multiple relay nodesparticipating in cooperative communication create alarger interference area and cause additional coordi-nation overhead thus affecting the overall through-put The authors in [25] proved that single relay nodeachieves the same diversity gain as that of multiplerelay nodes

In this paper distributed adaptive relay selection method isproposed In the proposed scheme selection of best relaynode is carried out when the direct transmission from thetransmitting node 119881119894 to receiving node 119881119894+1 in a multihopnetwork fails due to fading or the relay path transmissiontime is better than the direct path In such a scenariothe neighboring node with a potential to be a relay nodeparticipates in relay node selection process and uses localinformation collected by it The neighbor nodes will haveto satisfy certain QoS metric checks to qualify as the bestrelay node among the other competing neighboring nodesIf the direct transmission path between transmitting nodeand receiving node satisfies the QoS requirements the relaynodes will not participate in the communication and theprotocol will be reduced to simple DCF The neighbor nodesundergo the following QoS metric test to qualify as relaynode The various QoS metric tests a neighbor node has topass to qualify as a relay node to support cooperative MACmechanism are as follows

(1) For transmission time the first QoS metric is thetransmission time The neighbor node on hearingthe RTS and CTS between transmitting node 119881119894 andreceiving node 119881119894+1 estimates the data rate from theSNR of receiving signals Then it estimates the coop-erative transmission time that would incur between

the node 119881119894 and node 119881119894+1 if it participates as a relaynode The cooperative transmission time 119879coop andthe direct transmission time 119879direct are computed as

119879coop = 119871DR119881119894-119877119894

+ 119871DR119877119894-119881119894+1

+ 119879RE + 2 lowast 119879SIFS

119879direct = 119871DR119881119894-119881119894+1

(17)

where 119871 is the packet length 119879RE is the transmissiontime for RE frame which is sent by the candidaterelay node to 119881119894 and 119881119894+1 to notify its willingness toparticipate in the cooperative communication and119879SIFS is the short interframe space (SIFS) intervalIf the neighbor node prefers to be a relay nodethe total transmission time via relay node that is119879coop should be less than the direct transmission time119879direct

(2) For channel contentionmetric it focuses on the chan-nel contention In MANETs due to constant topo-logical change nodes may cluster at certain area andthere could be high inflow and outflow of data withinthat region leading to high interference Thereforethe average channel contention time of the node mayincrease thereby degrading the throughput of thenetwork In the proposed protocol a node havinga packet to forward will run a contention counter119879cc(119905) from the start of channel contention till itwins the channel access The average contention timefor a node 119879cc-avg(119905) is computed using exponentialweighted moving average over time Δ119905 and is givenby

119879cc-avg (119905) = 120572119879cc (119905) + (1 minus 120572) 119879cc-avg (119905 minus 1) (18)

where 120572 is a constant smoothing factor between 0 and1If the neighbor node prefers to be a relay node119879cc-avg(119905) should be less than 119879cc-thresh specifiedacceptable time duration

(3) For energy utilization factor the third metric energyefficiency is undoubtedly one of the apt metrics forquality evaluation The network lifetime is definedas the time from the deployment of the nodes tothe instant the first node dies So to maximize thenetwork lifetime data has to be routed such thatenergy expenditure is fairly among the nodes inproportion to their energy reservedThe energy levelsof all the nodes in the network have to be balancedand the nodes death due to frequent communicationshould be minimized to extend the network lifetimeIn the proposed algorithm the energy required by theneighbor node during cooperative communication iscomputed as

119864cooperative = 119875receiverDR119881119894-119877119894

+ 119875transmitterDR119877119894-119881119894+1

(19)


Framecontrol

Prioritybit FCS

2 bytes 6 bytes 6 bytes 6 bytes 2 bytes 1 byte 2 bytes 2 bytes 1 byte 2 bytes

Duration

2 bytes

Sequencecontrol

1 byte

Sourceaddress(Vi)

Next hopaddress(Vi+1)

Relayaddress(Ri)

Data rate Data rateLi-+1

L+1-(＄２-R) (＄２R-V+1

)

Figure 2 RE frame format

where 119875receiver is the power required to receive thedata packet from the source and 119875transmitter is thepower required to transmit the data packet to thedestination

Each neighbor node also stores its residual energy119864residual The proposed AMCCR protocol uses a novelway of interpreting energy using a metric called theenergy utilization factor to select a relay node that notonly is energy-efficient but also assists in improvingthe network lifetime The energy utilization metric 120576value is given as

120576 = 119864cooperative119864residual (20)

Energy utilizationmetric 120576 is a better parameter com-pared to 119864cooperative or 119864residual metric For exampleconsider the two neighbor nodes1198731 and1198732 satisfyingthe above two QoS metric tests Let us assume that1198731 and 1198732 have the residual energy of 30 J and 50 Jrespectively Many of the routing protocols select thenext hop based on residual energy or the minimumpower needed to transmit Let us assume that if1198731 or1198732 is selected as the relay node for cooperation theenergy required for transmission would be 10 J and25 J respectively So according to maximum residualenergy selection criteria 1198732 is selected and aftercooperative transmission the residual energy of 1198731and1198732 would be 30 J and 25 J respectively

According to the proposed energy utilization selec-tion metric the value of 120576 for 1198731 and 1198732 will be120576(1198731) = 1030 and 120576(1198732) = 2550 respectively Thenode with minimum 120576 will be selected that is node1198731 Thus after cooperative transmission the residualenergy of1198731 and1198732 would be 20 and 50 respectivelyEven though the 120576 factor does not guarantee totalenergy consumption minimization it maximizes theminimum value of 119864residual and maintains energylevels of the nodes in the network in a balanced stateTherefore this factor extends the node survival timeand improves the network lifetime

In the network theremay be several nodes that have qualifiedall the three QoS metric tests and are candidate nodes forbest relay node selection So to optimally select the bestrelay node each node computes the network utilizationweight based on the individual QoSmetric weight Each node

Table 1 Priority for 80211 data rate pair (119881119894-119877119894 119877119894-119881119894+1)Priority Data rate pair (119881119894-119877119894 119877119894-119881119894+1)1 54-54 54-48 54-36 54-24 54-18

2 48-48 48-36 48-24 48-54 48-18 36-36 36-24 36-5436-48 36-18

3 24-24 24-54 24-48 24-36 24-18 18-54 18-48 18-3618-24 18-18

4 54-12 54-9 48-12 48-95 36-12 36-9 24-96 24-12 18-12 18-97 12-54 12-48 12-36 12-24 12-18 12-12 12-98 9-54 9-48 9-36 9-24 9-18 9-12 9-9

computes its weight 119882relay at regular interval of time and isgiven by

119882relay = 1205751 lowast 119879coop119879coop-max+ 1205752 lowast 119879cc-avg119879cc-max

+ 1205753 lowast 120576 (21)

where sum3119894=1 120575119894 = 1 119879coop-max is the maximum acceptablecooperative transmission time and 119879cc-max is the maximumacceptable channel contention time

It can be seen from the above equation that the metricsare normalized by their maximum values with some multi-plicative factor 120575431 Relay Eligible Frame In the proposed scheme thecontrol format is extended to include source address nexthop address relay address data rates between source relayrelay next hop packet length from source to next hop andpacket length from next hop to source and priorityThis newcontrol format is known as relay eligible frame (RE) which isas shown in Figure 2

On completion of RTS and CTS exchange the nodesatisfying the condition to be a relay node sends the REframe On receiving the RE frame from a neighbor nodenode 119881119894 selects the appropriate MAC scheme If RE frameis not received within timeout the node 119881119894 adopts directtransmission The retransmission attempt is denied if REframes collide or the relay backoff counter is reduced to zeroThe sender node 119881119894 will transmit the data at rate DR119904minus119889 aftera SIFS

Each node maintains a priority table that consists of apair of data rate between transmitter-relay and relay-receiverpaths as shown in Table 1 The relay node on self-accessingsets the priority field in RE frame that matches with thecorresponding data rate pair as per Table 1 and forwardsthe RE frame to the transmitting node and the next hop


Table 2 Comparison of various relay selection schemes

Protocol Cooperation decision Centralization Selection overhead Network coding functionality Number of QoS metricsCD-MAC Transmitter Centralized Preselect historical information No SinglerDCF Receiver Distributed Preselect historical information No SingleCODE Transmitter Centralized Periodic broadcast Partial SingleCoopMAC Transmitter Centralized Passive monitoring No SingleUtdMAC Relay Centralized Preselect No SingleAMCCR Relay Distributed RTS-CTS contention Yes Multiple

Table 2 shows comparison of some of the existing schemesand proposed scheme for relay selection From Table 2 wecan infer the novelty of relay selection in our proposedAMCCR protocol which employs distributed relay selectionbased on multi-QoS metrics initiated by the relay based onlocal information

432 Relay SelectionOverhead Due to themobility of nodesmultiple relay nodes may be available satisfying the QoSmetric This may lead to collisions of RE frames Suchfrequent collisions may reduce the cooperation opportunityand degrade systemrsquos performance Thus it is a challengingtask to select the best relay efficiently with lower collision rateSo we need tomake a trade-off between relay selection periodand collision probability In order to avoid the collision ofRE frame from multiple nodes qualified to be a relay eachqualifying neighbor node waits for an additional 120582 time afterSIFS time We divide the 120582 time slot into multiple 120591 slots oflength 120590 120590 and 120591 are computed as

120590 = 2 lowast 119875delay + 119879switch

120591 = lfloor120582120590rfloor (22)

where 119875delay is a channel propagation delay and 119879switch istransceiver switching time

We further divide the time slots 120591 into 120601 to map 119882relayvalue which is given as

120601 = 119882relaymaxminus 119882relaymin120591 (23)

Each source node starts its 120601 counter from zero and when itreaches its119882relay value it sends RE frame in that time slot

433 Relay Reassignment Every relay nodemaintains a tablecontaining the information about the ongoing neighborstransmissionsThis restrains the neighbor nodes fromunnec-essarily participating in ongoing cooperative transmissionDue to nodes mobility fading or not satisfying the relayqualifying criteria the selected best relay nodemay no longerbe eligible to participate in the cooperative transmissionThe existing cooperative protocols mentioned in literaturedo not address the issue in case a selected relay goes offlineor is unavailable In such cases we propose a mechanism toautomatically reelect the new relay nodeThe neighbor nodeson not hearing the RE frame from the current relay node willspontaneously initiate the transmission of RE frame in the

next RE time slot So whichever neighbor node is successfulin forwarding the RE frame without collision replaces theprevious relay node as the current best relay node Theefficient relay selection scheme proposed in AMCCR has thefollowing characteristics

(1) Relay selection is time-efficient(2) Collision probability of relay selection is minimized(3) Relay selection dynamically adapts to time-varying

channel condition and nodes mobility(4) Relay selection is done in a distributed manner(5) There is no hidden node problem

44 Adaptive Cooperative MAC Schemes in AMCCR InAMCCR protocol the data transmission can be in one of thefour categories

(1) Direct transmission(2) Sender-relay-receiver(3) Cooperative transmission scheme using DF tech-

nique(4) Cooperative transmission scheme using AF tech-

nique

TheseMAC schemes are adaptively selected based on priorityfield of RE frame The cross-layer adaptive data transmissionis briefly explained in Algorithm 1 To facilitate the properselection of transmission scheme CTS packet is modified toaccommodate a flag known as FLAG P

441 Direct Transmission Based on the received signalquality transmitted from node 119881119894 the receiving node 119881119894+1sets its FLAG P field while replying with CTS If the directtransmission is sufficient that is SNR of received signal isgreater than SNRthresh then FLAG P is set to 0The neighbornode while decoding the CTS will notice the FLAG P fieldand refrain from interfering in the ongoing communicationif it is set to 0 Figure 3(a) demonstrates the scheme

442 Sender-Relay-Receiver Transmission If FLAG P is setto 1 and the priority field of RE frame contains the valuebetween 1 and 3 then AMCCR protocol prefers simplesender-relay-receiver transmission scheme Priority 1ndash3 indi-cates a high data rate estimated between the link 119881119894-119877119894 and119877119894-119881119894+1 and hence the probability of data received at relaynode or the receiver node with error is very minimal Since


(1) if RE frame not received within timeout then(2) Transmission mode = direct transmission(3) end if(4) if RE frame received then(5) Check the Priority field in RE frame(6) if 1 le Priority le 3 then(7) Transmission mode = sender-relay-receiver transmission(8) if 4 le Priority le 6 then(9) Transmission mode = DF cooperative transmission(10) else if Priority gt 6 then(11) Transmission mode = AF cooperative transmission(12) end if(13) end if(14) end if

Algorithm 1 Adaptive cooperative MAC data transmission

the transmission rate from sender node to relay node is toohigh receiver node does not overhear it due to reduced rangeand hence minimizes the interference

443 DF Cooperative Transmission When priority field ofRE frame contains the value between 4 and 6 the data rateestimate from source to relay node is higher compared tothat from relay node to destination node When the relayis located closer to the source terminal channel qualitybetween node 119881119894 and relay 119877119894 is better than that betweenrelay 119877119894 and node 119881119894+1 When relay 119877119894 moves away fromthe source the BER increases and the relay node may senderroneous bits to the destination Under this situation DFtechnique is always better than AF technique and guaranteesa performance diversity of the second order [26] Thereforewhen FLAG P is set to 1 and the priority field of RE framecontains the value between 4 and 6 AMCCR protocol prefersDF cooperative transmission DF technique is always betterthan AF technique and guarantees a performance diversity ofthe second order Figure 3(b) demonstrates the scheme

444 AF Cooperative Transmission If FLAG P is set to 1and the priority field of RE frame contains the value greaterthan 6 the AMCCR protocol prefers the AF cooperativetransmission Priority greater than 6 indicates low data rateestimate between 119881119894 and 119877119894 and high data rate estimatebetween 119877119894 and 119881119894+1 Performance in terms of BER is goodwhen the relay node is closer to the destination node As therelay node moves away from the destination signal strengthdrops due to high data rate Hence cooperative scheme withAF is preferred to guarantee a performance diversity of ordertwo as compared to DF scheme

On receiving the RE frame with priority bit the node119881119894+1 prepares for receiving data packets from relay node Thenode 119881119894 waits for SIFS time and sends data at the data rateDR119881119894-119877119894 to relay node On receiving the data packet relaynode waits for another SIFS time and forwards the packet todestination node119863 at the data rate DR119877119894-119881119894+1 On receiving thedata correctly node 119881119894+1 replies with an ACK packet to node119881119894 after SIFS

If node 119881119894 does not receive the RE frame withinTimeoutRE it prefers direct communication Figure 3(c)explains the scheme

45 Cooperative Routing In MANETs cooperation at theMAC layer can be exploited at the network layer to enhancethe systemrsquos performance Unlike the traditional routingprotocol we exploit theMACcooperationwhile selecting theroute from source to destination Thus cooperative routingis activated whenever the opportunity of cooperation gainexists Consider a simple network topology given in Figure 1Let us assume that the proposed routing scheme discovers theroute from node119881119894 to node119881119895 via nodes119881119894+1 and119881119894+2 duringinitial route discovery phase During the control packetexchange between 119881119894 and 119881119894+1 if 119877119894 qualifies to be the bestrelay node to support cooperative transmission then nodes119881119894 and 119881119894+1 will update their route table with the additionalentry for the relay nodeThus the route layer will have accessto cooperative link metrics of relay between two adjacentnodes The route layer fully exploits this information whilechoosing the best next hop from the route table The possibleroute from node 119881119894 to 119881119895 can be 119881119894-119877119894-119881119894+1-119881119894+2-119881119895 Hencethe cross-layer mechanism utilizes cooperative diversity thathelps in improving the network performance

5 Network Coding throughCooperative Communication

In a dual-hop half-duplex relay network the throughputperformance is reduced to half as it cannot transmit or receivesimultaneously To counter this fallback we implement thenetwork coding scheme in cooperative mode to supportefficient communication Network coding [27] is the tech-nique that forwards the data received frommultiple nodes bycombining the input data packets into one or more outputdata packets This results in a reduced number of packettransmissions reducing the delay and enhancing the networkperformance This technique is widely being accepted andcan be exploited in the cooperative communication Consideran example as shown in Figure 4 where nodes 119881119894 and


SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri

(a) Direct communicationSIFS

RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay

(b) Cooperative communication

SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ

(c) Network coding through cooperative transmission

Figure 3 (a) Direct communication (b) Cooperative communication (c) Network coding

119881119894+1 want to exchange the data packets for communicationthrough the selected relay node119877119894 Network coding techniqueworks in half-duplex mode which is divided into threephases where the channel is time-multiplexed Figure 3(c)demonstrates the exchange of control packets in cooperativecoding technique In phase 1 node 119881119894 forwards the datapacket 119871119881119894-119881119894+1 to relay 119877119894 In phase 2 node 119881119894+1 forwardsthe data packet 119871119881119894+1-119881119894 to relay 119877119894 Finally in phase 3 relay

node 119877119894 broadcasts 119871119881119894-119881119894+1 XOR 119871119881119894+1-119881119894 to nodes 119881119894 and119881119894+1 The nodes 119881119894 and 119881119894+1 recover the received data packetsdestined to themselves Therefore by implementing networkcoding scheme single-channel contention is needed At theend of phase 3 ACK packets are exchanged between nodes119881119894 and 119881119894+1 and transmission completes In case of ACKpacket getting lost retransmission of packet is initiated Thelength of packets from source to destination 119871119881119894-119881119894+1 and from


Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-

Figure 4 Network coding scheme

destination to the source 119871119881119894+1-119881119894 is computed through theduration values in RTS and CTS respectively The conditionfor relay node to participate in cooperative network codingtechnique is revised as

119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)

Figure 5 demonstrates the flow chart of detailed function-ality of proposed AMCCR protocol

6 NAV Adaptation

The IEEE 80211 wireless network uses a virtual carrier sens-ing mechanism that uses network allocation vector (NAV)NAV helps to limit the nodes access to wireless mediumwhich in turn avoids multiple interferences and conservesenergy The transmitting node specifies the transmissiontime required for the frames like RTS CTS and DATAduring which the channel will be busy All nodes listeningto channel on the network set their NAV for which theydefer their transmission The NAV is calculated based onthe transmission data rate In cooperative communicationsince the data rate varies based on relay node location andchannel condition setting NAV for RTS and CTS accuratelyis not feasible until the relay node information is availableto the source and the destination node Thus setting theeffective NAV is vital Updating the NAV of control packetsin proposed AMCCR protocol is described as follows

(1) Whenever a node 119881119894 has data to forward it sensesthe channel to check if it is idle for a DCF interframespace (DIFS) time Upon completing the requiredbackoff timer it sends RTS and reserves the channelfor RTSNAV time At this instance since119881119894 has no ideaabout the cooperation or network coding it uses basic

data rate to compute channel reservation based ondirect communication

RTSNAV = 4 lowast 119879SIFS + 119879CTS + 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119879ACK (25)

where 119871 is the length of the data packet and DR119881119894-119881119894+1is the data rate from node 119881119894 to node 119881119894+1

(2) The node 119881119894+1 on receiving RTS replies with CTSafter a SIFS time and reserves the channel for NAVduration CTSNAV

CTSNAV = 3 lowast 119879SIFS + 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119879ACK (26)

(3) When the neighboring node receives the RTS andCTS frame it checks if it is eligible to be a relay nodeas per best relay selection algorithm If it qualifiesto be a relay node it sends a RE frame to node119881119894 and node 119881119894+1 after a SIFS time and reservesthe channel for NAV duration of RENAV If CTSincludes the information for dual-hop half-duplexcommunication from 119881119894+1 the relay node prepares toforward the data using network coding scheme Elsethe protocol uses cooperative schemeFor cooperative scheme

RENAV = 2 lowast 119879SIFS + 119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)

For network coding scheme


+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)

(4) If node 119881119894 and node 119881119894+1 receive RE frame withintimeout they send the data through either coopera-tive technique or network coding Else node119881119894 sendsthe data packet through a direct transmission to node119881119894+1

REtimeout = 119879SIFS + 119879RE (29)


Start

amp computes SNR

FLAG_P = 0 FLAG_P = 1Yes No

A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B

remains silentnode Ri

Neighbour

Ri overhear RTSNeighbouring nodes

Vi sends RTS packet

SNR gt SN２ＮＢＬ

Vi+1 receives RTS

Neighbouring nodesVRi overhear CTS

Vi+1 includes Vi+1 hasdata for Vi

Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V

Vi+1 estimates ＄２Vi-Vi+1

Vi+1 includes amp FLAG_P in CTS and broadcast＄２Vi-Vi+1

Vi has data bytes to sendof LVi-Vi+1

Compute ＄２Vi+1-Ri

(a)

Yes

No

No

Yes

B

No

Yes

A

T＝ＩＩＪ and T＞ＣＬ＝Ｎ

Neighbour node Ri estimates

T＝ＩＩＪ lt T＞ＣＬ＝Ｎ

Node Ri estimates

Node Ri calculatesT＝＝-ＰＡ(t)

Neighbour

remains silent

node RiT＝＝-ＰＡ (t) gt T＝＝-ＮＢＬＭＢ

communication computes WＬＦＳ

Ri eligible for cooperative

gt ４ＢＬＭＢ

channel access and forwards RE packetNode Ri with min value of WＬＦＳ gets the

C

(b)

Figure 5 Continued


using directtransmission

packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE

technique AF technique

Yes No

Yes

No

Vi and Vi+1Vi sends datapackets to Vi+1

Vi sends data packet

Vi+1 sends data packet

Ri XOR the data

Vi+1 and Vi


Ri forwards datapacket to Vi+1


at time t1 (Ri overhears)

Ri forwards datapacket to Vi+1 attime t2 using DF

Ri forwards datapacket to Vi+1 attime t2 using

Vi+1 combines data

Vi+1 sendsACK to Vi

bytes to Riof LVi-Vi+1

LVi+1-Vi

bytes to Riof LVi+1-Vibytes to Riof LVi-Vi+1

bytes to Vi+1of LVi-Vi+1

1 le le 3priority

3 le le 6priority

(c)

Figure 5 Flow chart of the proposed AMCCR protocol

For cooperative scheme

DATA119881119894-119877119894 = 2 lowast 119879SIFS + 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)


DATA119881119894-119877119894 = 4 lowast 119879SIFS + 119871119889119904DR119877119894-119881119894+1

+ 2 lowast 119879ACK

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

DATA119881119894+1-119877119894 = 3 lowast 119879SIFS + 2 lowast 119879ACK

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

DATANC = 2 lowast 119879SIFS + 2 lowast 119879ACK

(31)

(5) On successful reception of data receiver node 119881119894+1sends ACK packet back to transmitter node 119881119894 If119881119894 receives ACK within ACKtimeout the data trans-mission is successful Else the transmitter node 119881119894resumes the backoff process to contend for the chan-nelFor cooperative scheme

ACKtimeout = 2 lowast 119879SIFS + 119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)


ACKtimeout = 2 lowast 119879SIFS + 119871119881119894-119877119894DR119881119894-119877119894

+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)

(6) The nodes that receive only RTS from S but not theCTS set their NAV until the end of ACK


Table 3 Simulation parameters in the MAC layer

Parameters ValueMAC header 272 bitsPHY header 192 bitsRate for MACPHY header 1MbpsRTS 352 bitsCTS 304 bitsACK 304 bitsSlot time 20 120583sSIFS 10 120583sDIFS 50 120583s119862119882min119862119882max 321024

7 Experimental Setup

In this section we analyze the performance of the proposedAMCCR by using the NS2 simulator [28] We evaluate theperformance of AMCCR by comparing the results withCD-MAC for cooperative mode and CODE for networkcoding The AMCCR is evaluated for MANETs based onIEEE 80211g In our simulation we consider a network overan area of 1000 lowast 100 meters The experiment is simulatedfor 900 sec time duration and the results are averaged after20 executions Each execution uses a seed value rangingfrom 1 to 9 for randomness in node placement and steadyresults The random movement of mobile nodes is modeledusing the random way-point modeling with a speed set to5msThe environment noise ismodeled asGaussian randomvariables level ranging from minus83 dBm to indicate harshcommunication environment to minus92 dBm to indicate a goodcommunication environment for 80211g with a standarddeviation of 1 dBm The source generates Constant Bit Rate(CBR) traffic packets at a rate of 5 packetss with size of512 bytesThe source-destination pairs are randomly selectedThe initial energy of all nodes is set to 60 J and 119864thresh isassumed to be 5 J The channels between each pair of nodesare set as independent Rayleigh fading channels The trans-mission rate of the data packet is computed as the averageSNRvalue of the received signal at the receiverThe channel inthe physical layer utilizes the multirate transmission definedin IEEE 80211g The simulation parameters assumed at theMAC layer are mentioned in Table 3

71 Performance Evaluation In this section we evaluate theperformance of the AMCCR protocol in different scenar-iosfirstly using the cooperative mode and secondly usingnetwork coding technique with varying environment noiselevel For cooperative mode AMCCR is compared with CD-MAC and noncooperative scheme 80211 DCF

711 Evaluation Metrics Evaluation metrics are listed asfollows

(1) Average end-to-end delay it is computed as theaverage delay experienced by packet from source todestination which is successfully delivered The delaytime comprises transmission delay propagation delay

node processing delay and queuing delay at eachintermediate node

(2) Throughput it is the ratio of the total amount of datathat reaches a receiver from a sender to the time ittakes the receiver to get the last packet It is expressedin bits per second

(3) Network lifetime the network lifetime of a nodedepends on the energy consumption in its own trans-missions as well as data transmission from neighbornodes Thus we compute the network lifetime withrespect to energy consumed per unit time Thus thenetwork lifetime depends on the energy consumptionduring both phases Thus we compute the networklifetime with respect to energy consumed per unittime Thus the lifetime of any node 119871119881 is computedas 119871119881 = 119864initial119864consumed where 119864consumed is energyconsumed per unit time The total network lifetimeis computed as NL = min119881120598119873(119871119881) where 119873 is totalnodes in the network

712 Cooperative Mode with Varying Number of Traffic FlowsIn this simulation we vary the network load that is byvarying the number of concurrent TCP traffic flows from 4 to20 with two different noise levels at a rate of 4 packetss Thenumber of nodes is assumed to be 50 randomly distributedThe source and destination nodes are randomly selected for aTCP connection pair

Figure 6(a) shows the throughput performance proposedAMCCR CD-MAC and noncooperative 80211 DCF pro-tocols All the protocols perform similarly in the initialstage But as the traffic load increases with deterioratingenvironment CD-MAC and noncooperative 80211 DCF pro-tocolsrsquo performance degrades Also as the network overheadincreases it leads to increase in packet collisions Interest-ingly the AMCCR offers excellent performance and betterthroughput improvement due to optimal relay node selectionfrom the lesser congested area with minimal overheadproviding the highest data rate for packet transmission andinfluencing the network throughput

In Figure 6(b) we observe the end-to-end delay perfor-mance of the AMCCR in comparison with CD-MAC andnoncooperative 80211 DCF protocols As the traffic flowincreases overall average delay increases for all the threeprotocols But AMCCR significantly performs better Thisis because of the adaptive cooperative approach in AMCCRthat uses higher dynamic data rate adaptation that decreasesthe average transmission time and allows more packets tobe transmitted faster via the relay node reducing the overalltransmission time duration Also in AMCCR if a packet islost due to the collision relay node forwards the backup copyof data packets reducing the retransmissions

Figure 6(c) compares the network lifetime as a function ofincreasing traffic load The lifetime of the network graduallydecreases with the increasing traffic load The reason for thedecline in the lifetime is the extra energy consumption bythe node and therefore it is exhausted early As AMCCR effi-ciently chooses nodes with optimal residual energy lifetime


8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow

80211 DCF (minus83 dBm)80211 DCF (minus92 dBm)CD-MAC (minus83 dBm)

CD-MAC (minus92 dBm)AMCCR (minus83 dBm)AMCCR (minus92 dBm)

(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)

Figure 6 AMCCRperformancewith varying TCP traffic (a)Throughput function (b) Average delay function (c)Network lifetime function

slowly declines and hence network is sustained for a longertime as compared to other two protocols

713 Cooperative Mode with Varying Node Density In thissimulation we vary the network density by varying thenetwork size from20nodes to 100 nodes at two different noiselevels with 10 TCP traffic flows between randomly selectedconnection pairs

Figure 7(a) shows the throughput performance of theproposed AMCCR CD-MAC and noncooperative 80211DCF protocols The throughput performance curve ofAMCCR is better compared to other protocols and performsconsistently better This is because the proposed protocol

dynamically adapts to channel conditions Also as the net-work density increases more relay nodes are available tosupport adaptive cooperative routing benefits for utilizinghigher data rates

Figure 7(b) shows the performance of average end-to-end delay of three protocols As the environment deteriorateswith the increase in node density the packet delay curve ofCD-MAC and noncooperative 80211 DCF protocols has anupsurge In AMCCR because of its judicious selection oftransmissionmode and relay node it optimizes the reliabilityand delay on hop-by-hop basis The AMCCR exploits higherdata rates offered by relay nodes to transmit packets reducingthe end-to-end delay




35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)

Figure 7 AMCCR performance with varying node density (a) Throughput function (b) Average delay function (c) Network lifetimefunction

Figure 7(c) shows the network lifetime performance Wecan observe that as the node density increases the networklifetime curve in the graph increases The network lifetimeof the proposed AMCCR performs comparatively better thanthe other protocols at noise level of minus92 dBm The AMCCRhas the longest lifetime as it optimally selects the nodes withsufficient energy level The other protocols underperform asnetwork lifetime is shorter

714 Network Coding with Varying Number of Traffic FlowsIn this simulation we vary the network load that is byvarying the number of UDP-based concurrent VOIP trafficsat two different noise levels The voice traffic is encoded into

a VoIP flow with ITU-T G711 [29] with average source bitrate of 64 kbps and the packet size of 160 bytes The numberof nodes is assumed to be 50We assume the number of flowsfrom4 to 20 with the source and destination nodes randomlyselected for aUDP connection pairWe compare theAMCCRprotocol with a cooperative communication scheme calledCODE and 80211 DCF under the network coding scheme InCODE network coding is partially utilized The relay nodeis randomly selected and not optimally by broadcasting themessages repeatedly

From Figure 8(a) we can analyze the throughput perfor-mance of AMCCR in comparison with two other protocolsThe proposed AMCCR even under the worst environment


80211 DCF (minus83 dBm)80211 DCF (minus92 dBm)CODE (minus83 dBm)

CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow

AMCCR (minus83 dBm)AMCCR (minus92 dBm)

(a)

80211 DCF (minus92 dBm)AMCCR (minus92 dBm)CODE (minus83 dBm)

CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow

80211 DCF (minus83 dBm)AMCCR (minus83 dBm)

(b)

Figure 8 AMCCR performance with varying node density (a) Throughput function (b) Average delay function

conditions shows 12ndash15 improved throughput compared toCODE The performance of 80211 DCF is the worst as itworks in a noncooperative method

Figure 8(b) shows the delay performance curve for allthree protocols against the UDP VOIP traffic The delayincreases with the increase in traffic and deteriorating envi-ronment The AMCCR outperforms CODE with 10ndash12reduction in delay as it optimally selects the best relay forcooperative coding The adaptive decisions on transmissionmode and relay selections at each hop in AMCCR providethe reliability and make it more robust to link failures thusenhancing the delay performance

8 Conclusions

The paper proposes a novel adaptive cooperative protocolAMCCR for MANETs In AMCCR we developed a cross-layer algorithm for energy-efficient routing in MANETsusing cooperative diversity In AMCCR routing schemeexploits the adaptive cooperative MAC scheme for reliabledata transfer AMCCR provides a distributed relay selectionscheme using multi-QoS metric to choose the best relay thatcan help to receive data packets and transmit to the next hopusing a cross-layer scheme It is observed that in order todesign an energy-efficient network for reliable data transferand to maximize the network lifetime joint cooperationbetween several layers is needed that is link quality in thephysical layer relay selection in theMAC layer and routing inthe network layerThe extensive simulation conducted showsthat in cooperativemode AMCCR significantly shows betterperformance in terms of throughput delay and network life-time compared to CD-MAC and 80211 DCF even under theharsh environmentThe proposed AMCCR also outperformstheCODEprotocol as it exploits both cooperation and codingtogether to enhance systemrsquos performance

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

References

[1] W A Jabbar M Ismail and R Nordin ldquoOn the performance ofThe currentMANET routing protocols forVoIPHTTPrdquo Journalof Computer Networks and Communications vol 2014 ArticleID 154983 16 pages 2014

[2] K R Anupama L J Gudino and M A Gawas ldquoCrosslayer adaptive congestion control for best-effort traffic of IEEE80211e in mobile ad hoc networksrdquo in Proceedings of the 10thInternational Symposium on Communication Systems Networksand Digital Signal Processing CSNDSP 2016 cze July 2016

[3] M A Gawas L J Gudino and K R Anupama ldquoCrosslayered adaptive cooperative routing mode in mobile ad hocnetworksrdquo in Proceedings of the 22nd Asia-Pacific Conference onCommunications APCC 2016 pp 462ndash469 idn August 2016

[4] A Scaglione D L Goeckel and J N Laneman ldquoCooperativecommunications in mobile ad hoc networksrdquo IEEE SignalProcessing Magazine vol 23 no 5 pp 18ndash29 2006

[5] A M Akhtar M R Nakhai and A H Aghvami ldquoOn the use ofcooperative physical layer network coding for energy efficientroutingrdquo IEEE Transactions on Communications vol 61 no 4pp 1498ndash1509 2013

[6] J N Laneman D N Tse and G Wornell ldquoCooperativediversity in wireless networks efficient protocols and outagebehaviorrdquo Institute of Electrical and Electronics Engineers Trans-actions on Information Theory vol 50 no 12 pp 3062ndash30802004

[7] TWang A Cano andG B Giannakis ldquoEfficient demodulationin cooperative schemes using decode-and-forward relaysrdquo inProceedings of the 39th Asilomar Conference on Signals Systemsand Computers pp 1051ndash1055 2005


[8] P Ju W Song and D Zhou ldquoSurvey on cooperative mediumaccess control protocolsrdquo IET Communications vol 7 no 9 pp893ndash902 2013

[9] N Sai Shankar C-T Chou and M Ghosh ldquoCooperativecommunicationMAC (CMAC) - A newMAC protocol for nextgeneration wireless LANsrdquo in Proceedings of the 2005 Interna-tional Conference on Wireless Networks Communications andMobile Computing pp 1ndash6 usa June 2005

[10] H Zhu andG Cao ldquorDCF a relay-enabledmedium access con-trol protocol for wireless ad hoc networksrdquo IEEE Transactionson Mobile Computing vol 5 no 9 pp 1201ndash1214 2006

[11] P Liu Z Tao S Narayanan T Korakis and S S PanwarldquoCoopMAC a cooperative MAC for wireless LANsrdquo IEEEJournal on Selected Areas in Communications vol 25 no 2 pp340ndash354 2007

[12] N Agarwal D ChanneGowda L N Kannan M Tacca andA Fumagalli ldquoIEEE 80211b cooperative protocols a perfor-mance studyrdquo in Proceedings of the 6th International IFIP-TC6Conference on Ad Hoc and Sensor Networks Wireless NetworksNext Generation Internet (NETWORKING rsquo07) pp 415ndash426Springer

[13] S Moh and C Yu ldquoA cooperative diversity-based robust MACprotocol in wireless ad hoc networksrdquo IEEE Transactions onParallel andDistributed Systems vol 23 no 3 pp 353ndash363 2012

[14] F Mansourkiaie and M H Ahmed ldquoCooperative routing inwireless networks a comprehensive surveyrdquo IEEE Communica-tions Surveys and Tutorials vol 17 no 2 pp 604ndash626 2015

[15] C E Perkins and E M Royer ldquoAd-hoc on-demand distancevector routingrdquo in Proceedings of the 2nd IEEE Workshop onMobile Computing Systems and Applications (WMCSA rsquo99) pp90ndash100 New Orleans La USA February 1999

[16] V Srivastava and M Motani ldquoCross-layer design a survey andthe road aheadrdquo IEEE Communications Magazine vol 43 no12 pp 112ndash119 2005

[17] J A Stine ldquoCross-layer design of MANETs the only Optionrdquoin Proceedings of theMilitary Communications Conference 2006MILCOM 2006 October 2006

[18] M Dehghan M Ghaderi and D Goeckel ldquoMinimum-energycooperative routing in wireless networks with channel varia-tionsrdquo IEEE Transactions on Wireless Communications vol 10no 11 pp 3813ndash3823 2011

[19] F Mansourkiaie M H Ahmed and Y Gadallah ldquoMinimizingthe probability of collision in wireless sensor networks usingcooperative diversity and optimal power allocationrdquo in Proceed-ings of the 2013 9th International Wireless Communications andMobile Computing Conference IWCMC 2013 pp 120ndash124 July2013

[20] L Wang and K Liu ldquoAn throughput-optimized cooperativerouting protocol in ad hoc networkrdquo in Proceedings of the 20093rd IEEE International Symposium on Microwave AntennaPropagation and EMC Technologies for Wireless Communica-tions MAPE 2009 pp 1255ndash1258 October 2009

[21] M Mohammadi H A Suraweera and X Zhou ldquoOutageprobability of wireless ad hoc networks with cooperative relay-ingrdquo in Proceedings of the 2012 IEEE Global CommunicationsConference GLOBECOM 2012 pp 4410ndash4416 December 2012

[22] V K Sakarellos D Skraparlis A D Panagopoulos and J DKanellopoulos ldquoCooperative diversity performance of selectionrelaying over correlated shadowingrdquo Physical Communicationvol 4 no 3 pp 182ndash189 2011

[23] T Kunz and R Alhalimi ldquoEnergy-efficient proactive routing inMANET energymetrics accuracyrdquoAdHoc Networks vol 8 no7 pp 755ndash766 2010

[24] B Guo Q Guan F R Yu S Jiang andV CM Leung ldquoEnergy-efficient topology control with selective diversity in cooperativewireless ad hoc networks a game-theoretic approachrdquo IEEETrans Wireless Communications vol 13 no 11 pp 6484ndash64952014

[25] X Liang I Balasingham and V C M Leung ldquoCooperativecommunications with relay selection for QoS provisioning inwireless sensor networksrdquo in Proceedings of the 2009 IEEEGlobal Telecommunications Conference GLOBECOM2009 usaDecember 2009

[26] J Boyer D D Falconer and H Yanikomeroglu ldquoMultihopdiversity in wireless relaying channelsrdquo IEEE Transactions onCommunications vol 52 no 10 pp 1820ndash1830 2004

[27] S R Li R W Yeung and N Cai ldquoLinear network codingrdquoInstitute of Electrical and Electronics Engineers Transactions onInformation Theory vol 49 no 2 pp 371ndash381 2003

[28] The Network Simulator NS-2 httpwwwisiedunsnamns[29] Y Hiwasaki and H Ohmuro ldquoITU-T G7111 extending G711

to higher-quality wideband speechrdquo IEEE CommunicationsMagazine vol 47 no 10 pp 110ndash116 2009

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of


International Journal of

RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal of

Volume 201

Submit your manuscripts athttpswwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



layers In the recent time the cooperative MAC scheme inad hoc wireless networks has also attracted much attention[8]These schemes use handshaking techniques to reserve thechannel and avoid the collision problemsThese schemes usecross-layer design between the physical and MAC layers forrelay selection with the criteria related to rate adaptation andpower control Due to random nature of the wireless channelMAC layer should know when to initiate the cooperativetransmission Thus the cooperative MAC should utilize theassistance from a relay node to forward the data using betterlink adaptation techniques and higher data rates to enhancethe network throughput

Usage of cooperative communication together with rateadaptation techniques can enable the nodes to adapt theirdata rates tomatch the channel conditions and nodemobilityCombining both these techniques can provide a substantialthroughput improvement in direct and conventional multi-hop network

In this paper we establish cooperation between physicalMAC and network layers We propose an effective dis-tributed cross-layer cooperative routing algorithm formobilenodes by using multi-QoS cooperative metrics that use thepotential cooperation gain to find the optimal route Thecross-layer coordination between the MAC and networklayers is used to select an optimal next hop while the cross-layer coordination between the MAC and physical layers isused to select the best relay

The main objectives of the proposed algorithm are asfollows

(1) An energy-aware end-to-end delay efficient routediscovery scheme is proposed among the networknodes in order to increase the network lifetime

(2) Using the channel state information at the physicallayer the proposed algorithm determines whethercooperation on the link is necessary or not

(3) In case the cooperation on the link is necessarymulti-QoS metric is used to determine the potential relaynodes for a cooperative transmission over each linkThe cooperative mode activation is implemented inthe MAC layer

(4) We exploit the cross-layer approach to the routinglayer for relay selections and resource allocationsthat reflect the potential cooperation gain to find theoptimal paths The best relay node selection strategyis executed in distributed manner

(5) The proposed algorithm is analyzed with single relayparticipation for cooperative scheme and furtherextended for supporting network coding scheme

(6) The best relay selection is enabled with collisionavoidance mechanism

The rest of the paper is organized as follows Section 2discusses the related work In Section 3 we describe thephysical model and assumptions Section 4 describes ouradaptive cooperative cross-layer architecture In Section 5we propose our cooperative network coding technique TheNAV is analyzed in Section 6 Performance evaluation andconclusions are presented in Sections 7 and 8 respectively

2 Related Work

In the recent time the cooperative MAC schemes in adhoc wireless networks have attracted much attention Theseschemes use handshaking techniques to reserve the channeland avoid the collision problems These schemes uses cross-layer design between the physical and MAC layers for relayselection with the criteria related to rate adaptation andpower control

Sai Shankar et al proposed a protocol called CMAC[9] with minor modifications to the standard IEEE 80211Distributed Coordination Function (DCF) When the sourcenode sends the data packets and if destination node receivesthem with errors or fails to receive them the source nodeselects a cooperative relay node to forward the lost datapacket Although CMAC provides the reliability of datatransmission and throughput enhancement it assumes thatthe link between any nodes is ideal and error-free The relay-enabled DCF (rDCF) [10] and cooperative MAC (Coop-MAC) [11] were proposed to exploit the multirate capabilityand counter the throughput bottleneck caused by the lowdatarate linksTheCoopMACand rDCFprotocols choose to sendpackets at a high data rate using relay node in a two-hopman-ner instead of a low data rate with direct transmission andimprove the network performance In rDCF the best relaynode is selected by the receiver based on the piggybackedinformation in the control frame Meanwhile in CoopMACthe relay node itself decides whether to cooperate or notbased on its local information maintained in the cooperativetable Both protocols are not suitable for multihop ad hocnetworks and do not have any provision to deal with hiddennode and exposed node In UtdMAC [12] data packets aretransmitted through the relay whenever a direct transmissionfails due to fading But in UtdMAC it is assumed that therelay is selected a priori and will be ready to transmit in acooperative method whenever necessary Thus this protocoldoes not have to deal with much of the relay selection over-head andmanagementThe cooperative diversity MAC (CD-MAC) proposed by [13] is based on the DCF mode In CD-MAC nodes use Distributed Space-Time Coding (DSTC)In CD-MAC the transmission of multiple copies of a datastream is distributed among the cooperating nodes which actas a virtual antenna array The cooperating nodes encode thedata by using orthogonal codes and simultaneously transmitit to the destination The packet scheduling technique CD-MAC is similar to that of ARQ scheme where cooperationis triggered when a direct transmission of a control packetfails A source node sends an RTS packet to the destinationnode If the destination replies with a CTS before the timeoutperiod expires then CD-MAC does not initiate cooperationelse it activates the cooperation in the next phase Thesource node intimates the need for cooperation to relay nodesthrough repeated RTS (C-RTS) packet The destination nodereplies to a C-RTS with C-CTS simultaneously to relay andsource node During cooperation using DSTC source nodefirst sends a packet to the relay in the first phase and thenboth the source and relay simultaneously transmit the codedpacket to the destination node In CD-MAC each nodemaintains an estimate of neighbor nodes link quality through






3 System Model






119910119881119894 119881119894+1 = radic1198751ℎ119881119894 119881119894+1119909 + 120578119881119894 119881119894+1119910119881119894 119877119894 = radic1198751ℎ119881119894 119877119894119909 + 120578119881119894 119877119894 (1)



119862AF = 119882 sdot 119868AF (119881119894 119881119894+1 119877119894) (2)



SNR119881119894 119877119894 + SNR119877119894 119881119894+1 + 1)SNR119881119894 119881119894+1 = 11987511205902119881119894 119881119894+1

10038161003816100381610038161003816ℎ119881119894 119881119894+1 100381610038161003816100381610038162SNR119881119894 119877119894 = 11987511205902119881119894 119877119894

10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162SNR119877119894 119881119894+1 = 11987521205902119877119894 119881119894+1

10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162

(3)


119910119877119894 119881119894+1 = radic11987511198752radic1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730

ℎ119877119894 119881119894+1ℎ119881119894 119877119894119909 + 1205781015840119877119894 119881119894+1 (4)


where

1205781015840119877119894 119881119894+1 = radic1198752radic1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730

ℎ119877119894 119881119894+1120578119881119894 119877119894 + 120578119877119894 119881119894+1 (5)


( 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730 + 1)1198730 (6)


119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (7)


1198861 = radic1198751ℎlowast119881119894 119881119894+11198730


(8)


120574 = 1205741 + 1205742 (9)


1205741 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 1003816100381610038161003816100381621198730 1205742 = 11198730

11987511198752 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162 + 1198730 (10)



119862DF = 119882 sdot 119868DF (119881119894 119877119894 119881119894+1) (11)




119910119903119889 = radic1198752ℎ119877119894 119881119894+1119909 + 120578119877119894 119881119894+1 (13)


119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (14)


1198861 = radic1198751ℎ119881119894 119881119894+11198730 1198862 = radic1198752ℎ119877119894 119881119894+11198730

(15)


120574 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198730 (16)








R1 R2 Rn

R3

Vi Vi+1 Vi+2 Vj














119879coop = 119871DR119881119894-119877119894

+ 119871DR119877119894-119881119894+1

+ 119879RE + 2 lowast 119879SIFS

119879direct = 119871DR119881119894-119881119894+1

(17)







+ 119875transmitterDR119877119894-119881119894+1

(19)


Framecontrol

Prioritybit FCS


Duration

2 bytes

Sequencecontrol

1 byte

Sourceaddress(Vi)


Relayaddress(Ri)


L+1-(＄２-R) (＄２R-V+1

)









2 48-48 48-36 48-24 48-54 48-18 36-36 36-24 36-5436-48 36-18

3 24-24 24-54 24-48 24-36 24-18 18-54 18-48 18-3618-24 18-18

4 54-12 54-9 48-12 48-95 36-12 36-9 24-96 24-12 18-12 18-97 12-54 12-48 12-36 12-24 12-18 12-12 12-98 9-54 9-48 9-36 9-24 9-18 9-12 9-9



+ 1205753 lowast 120576 (21)











120591 = lfloor120582120590rfloor (22)












nique
















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














3 System Model






119910119881119894 119881119894+1 = radic1198751ℎ119881119894 119881119894+1119909 + 120578119881119894 119881119894+1119910119881119894 119877119894 = radic1198751ℎ119881119894 119877119894119909 + 120578119881119894 119877119894 (1)



119862AF = 119882 sdot 119868AF (119881119894 119881119894+1 119877119894) (2)



SNR119881119894 119877119894 + SNR119877119894 119881119894+1 + 1)SNR119881119894 119881119894+1 = 11987511205902119881119894 119881119894+1

10038161003816100381610038161003816ℎ119881119894 119881119894+1 100381610038161003816100381610038162SNR119881119894 119877119894 = 11987511205902119881119894 119877119894

10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162SNR119877119894 119881119894+1 = 11987521205902119877119894 119881119894+1

10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162

(3)


119910119877119894 119881119894+1 = radic11987511198752radic1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730

ℎ119877119894 119881119894+1ℎ119881119894 119877119894119909 + 1205781015840119877119894 119881119894+1 (4)


where

1205781015840119877119894 119881119894+1 = radic1198752radic1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730

ℎ119877119894 119881119894+1120578119881119894 119877119894 + 120578119877119894 119881119894+1 (5)


( 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730 + 1)1198730 (6)


119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (7)


1198861 = radic1198751ℎlowast119881119894 119881119894+11198730


(8)


120574 = 1205741 + 1205742 (9)


1205741 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 1003816100381610038161003816100381621198730 1205742 = 11198730

11987511198752 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162 + 1198730 (10)



119862DF = 119882 sdot 119868DF (119881119894 119877119894 119881119894+1) (11)




119910119903119889 = radic1198752ℎ119877119894 119881119894+1119909 + 120578119877119894 119881119894+1 (13)


119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (14)


1198861 = radic1198751ℎ119881119894 119881119894+11198730 1198862 = radic1198752ℎ119877119894 119881119894+11198730

(15)


120574 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198730 (16)








R1 R2 Rn

R3

Vi Vi+1 Vi+2 Vj














119879coop = 119871DR119881119894-119877119894

+ 119871DR119877119894-119881119894+1

+ 119879RE + 2 lowast 119879SIFS

119879direct = 119871DR119881119894-119881119894+1

(17)







+ 119875transmitterDR119877119894-119881119894+1

(19)


Framecontrol

Prioritybit FCS


Duration

2 bytes

Sequencecontrol

1 byte

Sourceaddress(Vi)


Relayaddress(Ri)


L+1-(＄２-R) (＄２R-V+1

)









2 48-48 48-36 48-24 48-54 48-18 36-36 36-24 36-5436-48 36-18

3 24-24 24-54 24-48 24-36 24-18 18-54 18-48 18-3618-24 18-18

4 54-12 54-9 48-12 48-95 36-12 36-9 24-96 24-12 18-12 18-97 12-54 12-48 12-36 12-24 12-18 12-12 12-98 9-54 9-48 9-36 9-24 9-18 9-12 9-9



+ 1205753 lowast 120576 (21)











120591 = lfloor120582120590rfloor (22)












nique
















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










where

1205781015840119877119894 119881119894+1 = radic1198752radic1198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730

ℎ119877119894 119881119894+1120578119881119894 119877119894 + 120578119877119894 119881119894+1 (5)


( 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198730 + 1)1198730 (6)


119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (7)


1198861 = radic1198751ℎlowast119881119894 119881119894+11198730


(8)


120574 = 1205741 + 1205742 (9)


1205741 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 1003816100381610038161003816100381621198730 1205742 = 11198730

11987511198752 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198751 10038161003816100381610038161003816ℎ119881119894 119877119894 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 100381610038161003816100381610038162 + 1198730 (10)



119862DF = 119882 sdot 119868DF (119881119894 119877119894 119881119894+1) (11)




119910119903119889 = radic1198752ℎ119877119894 119881119894+1119909 + 120578119877119894 119881119894+1 (13)


119910 = 1198861119910119881119894 119881119894+1 + 1198862119910119877119894 119881119894+1 (14)


1198861 = radic1198751ℎ119881119894 119881119894+11198730 1198862 = radic1198752ℎ119877119894 119881119894+11198730

(15)


120574 = 1198751 10038161003816100381610038161003816ℎ119881119894 119881119894+1 100381610038161003816100381610038162 + 1198752 10038161003816100381610038161003816ℎ119877119894 119881119894+1 1003816100381610038161003816100381621198730 (16)








R1 R2 Rn

R3

Vi Vi+1 Vi+2 Vj














119879coop = 119871DR119881119894-119877119894

+ 119871DR119877119894-119881119894+1

+ 119879RE + 2 lowast 119879SIFS

119879direct = 119871DR119881119894-119881119894+1

(17)







+ 119875transmitterDR119877119894-119881119894+1

(19)


Framecontrol

Prioritybit FCS


Duration

2 bytes

Sequencecontrol

1 byte

Sourceaddress(Vi)


Relayaddress(Ri)


L+1-(＄２-R) (＄２R-V+1

)









2 48-48 48-36 48-24 48-54 48-18 36-36 36-24 36-5436-48 36-18

3 24-24 24-54 24-48 24-36 24-18 18-54 18-48 18-3618-24 18-18

4 54-12 54-9 48-12 48-95 36-12 36-9 24-96 24-12 18-12 18-97 12-54 12-48 12-36 12-24 12-18 12-12 12-98 9-54 9-48 9-36 9-24 9-18 9-12 9-9



+ 1205753 lowast 120576 (21)











120591 = lfloor120582120590rfloor (22)












nique
















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














R1 R2 Rn

R3

Vi Vi+1 Vi+2 Vj














119879coop = 119871DR119881119894-119877119894

+ 119871DR119877119894-119881119894+1

+ 119879RE + 2 lowast 119879SIFS

119879direct = 119871DR119881119894-119881119894+1

(17)







+ 119875transmitterDR119877119894-119881119894+1

(19)


Framecontrol

Prioritybit FCS


Duration

2 bytes

Sequencecontrol

1 byte

Sourceaddress(Vi)


Relayaddress(Ri)


L+1-(＄２-R) (＄２R-V+1

)









2 48-48 48-36 48-24 48-54 48-18 36-36 36-24 36-5436-48 36-18

3 24-24 24-54 24-48 24-36 24-18 18-54 18-48 18-3618-24 18-18

4 54-12 54-9 48-12 48-95 36-12 36-9 24-96 24-12 18-12 18-97 12-54 12-48 12-36 12-24 12-18 12-12 12-98 9-54 9-48 9-36 9-24 9-18 9-12 9-9



+ 1205753 lowast 120576 (21)











120591 = lfloor120582120590rfloor (22)












nique
















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

















119879coop = 119871DR119881119894-119877119894

+ 119871DR119877119894-119881119894+1

+ 119879RE + 2 lowast 119879SIFS

119879direct = 119871DR119881119894-119881119894+1

(17)







+ 119875transmitterDR119877119894-119881119894+1

(19)


Framecontrol

Prioritybit FCS


Duration

2 bytes

Sequencecontrol

1 byte

Sourceaddress(Vi)


Relayaddress(Ri)


L+1-(＄２-R) (＄２R-V+1

)









2 48-48 48-36 48-24 48-54 48-18 36-36 36-24 36-5436-48 36-18

3 24-24 24-54 24-48 24-36 24-18 18-54 18-48 18-3618-24 18-18

4 54-12 54-9 48-12 48-95 36-12 36-9 24-96 24-12 18-12 18-97 12-54 12-48 12-36 12-24 12-18 12-12 12-98 9-54 9-48 9-36 9-24 9-18 9-12 9-9



+ 1205753 lowast 120576 (21)











120591 = lfloor120582120590rfloor (22)












nique
















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Framecontrol

Prioritybit FCS


Duration

2 bytes

Sequencecontrol

1 byte

Sourceaddress(Vi)


Relayaddress(Ri)


L+1-(＄２-R) (＄２R-V+1

)









2 48-48 48-36 48-24 48-54 48-18 36-36 36-24 36-5436-48 36-18

3 24-24 24-54 24-48 24-36 24-18 18-54 18-48 18-3618-24 18-18

4 54-12 54-9 48-12 48-95 36-12 36-9 24-96 24-12 18-12 18-97 12-54 12-48 12-36 12-24 12-18 12-12 12-98 9-54 9-48 9-36 9-24 9-18 9-12 9-9



+ 1205753 lowast 120576 (21)











120591 = lfloor120582120590rfloor (22)












nique
















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation















120591 = lfloor120582120590rfloor (22)












nique
















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation





















SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










SIFS

RTS

CTS ACK

SIFS SIFS

DATA

DIFS BACKOFF

NAV

Vi

Vi+1

Ri


RTS

CTS ACK

SIFS SIFS SIFS SIFS

DATA

NAV

RE DATA

DIFS BACKOFF

Φ

Source

Best Relay

Next hop

Loser Relay


SIFS

RTS

CTS

ACK

SIFS SIFS SIFS SIFS

ACK

SIFS SIFS

DATA

RE

DATA

DIFS

Source

Best Relay

Next hop

DATA

BACKOFF

Φ






Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Phase 1

Phase 2

Phase 3ACKACK

Vi

Vi

Vi

Vi

Vi+1

Vi+1

Vi+1

Vi+1

Ri

Ri

Ri

Ri

L-+1

L-+1L-+1L+1-

L+1-

L+1-



119871119881119894-119881119894+1DR119881119894-119877119894

+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894 DR119877119894-119881119894+1)

+ 119879RE

lt 119871119881119894-119881119894+1DR119881119894-119881119894+1

+ 119871119881119894+1-119881119894DR119881119894-119881119894+1

+ 119879RTS + 119879CTS + 119879SIFS

+ 119879DIFS + 119879backoff

(24)


6 NAV Adaptation





+ 119879ACK (25)




+ 119879ACK (26)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

(27)



+ 119871119881119894+1-119881119894DR119877119894-119881119894+1

+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)

(28)




Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Start

amp computes SNR


A

Yes

No

NAV set

No

NAV set

No

B

Yes

remains silentYes

B


Neighbour


Vi sends RTS packet


Vi+1 receives RTS



Neighbour node Ri

Compute ＄２Vi-Ri

in CTSLVi+1-V





(a)

Yes

No

No

Yes

B

No

Yes

A




Node Ri estimates


Neighbour

remains silent




gt ４ＢＬＭＢ


C

(b)

Figure 5 Continued



packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











packets using MRC

C

receive RE

Stop

Yes No

CTS includes

packet amp sends to

No

Yes

B

Priority in RE

Priority in RE


Yes No

Yes

No




Ri XOR the data

Vi+1 and Vi







Vi+1 combines data

Vi+1 sendsACK to Vi


LVi+1-Vi



1 le le 3priority

3 le le 6priority

(c)




+ 119879ACKDATA119877119894-119881119894+1 = 119879SIFS + 119879ACK

(30)




+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


+ max (119871119881119894-119881119894+1 119871119881119894+1-119881119894)min (DR119881119894-119877119894DR119877119894-119881119894+1)


(31)



+ 119871119881119894-119881119894+1DR119877119894-119881119894+1

+ 119879ACK(32)



+ 119871119877119894-119881119894+1DR119877119894-119881119894+1

+ 2lowast 119879ACK

(33)


















8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

























8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










8

7

6

5

4

3

2

1

Thro

ughp

ut (M

bps)

4 8 12 16 20

TCP traffic flow



(a)

12

1

08

06

04

02

0

Aver

age e

nd-to

-end

del

ay (s

)

4 8 12 16 20

TCP traffic flow



(b)

600

550

500

450

400

350

300

250

200

150

Life

time (

s)

20 40 60 80 100

TCP traffic flow



(c)










35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












35

3

25

2

15

1

Thro

ughp

ut (M

bps)

20 40 60 80 100

Node density

(a)



08

07

06

05

04

03

02

01

Aver

age e

nd-to

-end

del

ay (s

)

20 40 60 80 100

Node density

(b)



600

550

500

450

400

Net

wor

k lif

etim

e (s)

20 40 60 80 100

Node density

(c)








CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











CODE (minus92 dBm)

35

3

25

2

15

1

05

0

Thro

ughp

ut (M

bps)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(a)


CODE (minus92 dBm)

350

300

250

200

150

100

50

0

Aver

age e

nd-to

-end

del

ay (s

)

4 6 8 10 12 14 16 18 20

VoIP traffic flow


(b)




8 Conclusions




References































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation
































RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









RoboticsJournal of





Journal of



RotatingMachinery



Journal of

Volume 201


VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









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AMCCR: Adaptive Multi-QoS Cross-Layer Cooperative Routing ...downloads.hindawi.com/journals/jcnc/2017/3638920.pdf · ResearchArticle AMCCR: Adaptive Multi-QoS Cross-Layer Cooperative