IEEE Final Year Projects 2011-2012 :: Elysium Technologies Pvt Ltd::Mobilecomputingnew

Elysium Technologies Private Limited ISO 9001:2008 A leading Research and Development Division Madurai | Chennai | Trichy | Coimbatore | Kollam| Singapore Website: elysiumtechnologies.com, elysiumtechnologies.info Email: [email protected]

IEEE Final Year Project List 2011-2012

Madurai

Elysium Technologies Private Limited

230, Church Road, Annanagar,

Madurai , Tamilnadu – 625 020.

Contact : 91452 4390702, 4392702, 4394702.

eMail: [email protected]

Trichy


3rd

Floor,SI Towers,

15 ,Melapudur , Trichy,

Tamilnadu – 620 001.

Contact : 91431 - 4002234.


Kollam


Surya Complex,Vendor junction,

kollam,Kerala – 691 010.

Contact : 91474 2723622.


A b s t r a c t MOBILE COMPUTING 2011 - 2012

01 A Control-Theoretic Approach to Distributed Optimal Configuration of 802.11 WLANs

The optimal configuration of the contention parameters of a WLAN depends on the network conditions in terms of

number of stations and the traffic they generate. Following this observation, a considerable effort in the literature has

been devoted to the design of distributed algorithms that optimally configure the WLAN parameters based on current

conditions. In this paper, we propose a novel algorithm that, in contrast to previous proposals which are mostly

based on heuristics, is sustained by mathematical foundations from multivariable control theory. A key advantage of

the algorithm over existing approaches is that it is compliant with the 802.11 standard and can be implemented with

current wireless cards without introducing any changes into the hardware or firmware. We study the performance of

our proposal by means of theoretical analysis, simulations, and a real implementation. Results show that the

algorithm substantially outperforms previous approaches in terms of throughput and delay.

02 A Cooperative Clustering Protocol for Energy Saving of Mobile Devices with WLAN and Bluetooth Interfaces

One of the most widely used wireless communication standards is a Wireless Local Area Network (WLAN) (IEEE 802.11).

However, WLAN has a serious power consumption problem. In this paper, we propose a novel energy saving approach that

exploits the multiradio feature of recent mobile devices equipped with WLAN and Bluetooth interfaces. Unlike previous

approaches, our work is based on clustering. In our work, a cluster is a Bluetooth Personal Area Network (PAN), which

consists of one cluster head and several regular nodes. The cluster head acts as a gateway between the PAN and the

WLAN, enabling the regular nodes to access the WLAN infrastructure via low-power Bluetooth. We present a distributed

clustering protocol, Cooperative Networking protocol (CONET), which dynamically reforms clusters according to each

node’s bandwidth requirement, energy use, and application type. CONET does not require modifications of existing

wireless infrastructures because clustering is performed independently of WLAN access points. We implemented the

CONET prototype with four wearable computing devices to evaluate the performance on real hardware. We also simulated

CONET for large networks of more than 100 mobile nodes. Both results demonstrate that our approach is effective in

reducing the power consumption of WLAN.

03 A Distributed and Scalable Time Slot Allocation Protocol for Wireless Sensor Networks

There are performance deficiencies that hamper the deployment of Wireless Sensor Networks (WSNs) in critical

monitoring applications. Such applications are characterized by considerable network load generated as a result of

sensing some characteristics of the monitored system. Excessive packet collisions lead to packet losses and

retransmissions, resulting in significant overhead costs and latency. In order to address this issue, we introduce a

distributed and scalable scheduling access scheme that mitigates high data loss in data-intensive sensor networks

and can also handle some mobility. Our approach alleviates transmission collisions by employing virtual grids that

1



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


adopt Latin Squares characteristics to time slot assignments. We show that our algorithm derives conflictfree time

slot allocation schedules without incurring global overhead in scheduling. Furthermore, we verify the effectiveness

of our protocol by simulation experiments. The results demonstrate that our technique can efficiently handle sensor

mobility with acceptable data loss, low packet delay, and low overhead.

04 A Medium Access Control Scheme for Wireless LANs with Constant-Time Contention

In today’s wireless networks, stations using the IEEE 802.11 Standard contend for the channel using the Distributed

Coordination Function (DCF). Research has shown that DCF’s performance degrades especially with the large number of

stations. This becomes more concerning due to the increasing proliferation of wireless devices. In this paper, we present a

Medium Access Control (MAC) scheme for wireless LANs and compare its performance to DCF and to other efficient

schemes. Our scheme, which attempts to resolve the contention in a constant number of slots (or constant time), is called

CONTI. The contention resolution happens over a predefined number of slots. In a slot, the stations probabilistically send a

jam signal on the channel. The stations listening retire if they hear a jam signal. The others continue to the next slot. Over

several slots, we aim to have one station remaining in the contention, which will then transmit its data. We find the optimal

parameters of CONTI and present an analysis on its performance. More comprehensive evaluation is presented in the

simulation results where we compare CONTI, DCF, and other efficient schemes from the literature. We consider the number

of slots used, the collision rate, the throughput, the delay, and the fairness. The highest throughput was achieved by

CONTI. Moreover, our results provide measurements from each of the schemes that we consider and provide the insight on

each scheme’s operation.

05 A Privacy-Preserving Location Monitoring System for Wireless Sensor Networks

Monitoring personal locations with a potentially untrusted server poses privacy threats to the monitored individuals.

To this end, we propose a privacy-preserving location monitoring system for wireless sensor networks. In our

system, we design two innetwork location anonymization algorithms, namely, resource and quality-aware algorithms,

that aim to enable the system to provide high-quality location monitoring services for system users, while preserving

personal location privacy. Both algorithms rely on the wellestablished k-anonymity privacy concept, that is, a person

is indistinguishable among k persons, to enable trusted sensor nodes to provide the aggregate location information

of monitored persons for our system. Each aggregate location is in a form of a monitored area A along with the

number of monitored persons residing in A, where A contains at least k persons. The resource-aware algorithm aims

to minimize communication and computational cost, while the quality-aware algorithm aims to maximize the

accuracy of the aggregate locations by minimizing their monitored areas. To utilize the aggregate location

information to provide location monitoring services, we use a spatial histogram approach that estimates the

distribution of the monitored persons based on the gathered aggregate location information. Then, the estimated

distribution is used to provide location monitoring services through answering range queries. We evaluate our

system through simulated experiments. The results show that our system provides high-quality location monitoring

services for system users and guarantees the location privacy of the monitored persons.

2



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


06 A Spectrum Decision Framework for Cognitive Radio Networks

Cognitive radio networks have been proposed as a solution to both spectrum inefficiency and spectrum scarcity problems.

However, they face to a unique challenge based on the fluctuating nature of heterogeneous spectrum bands as well as the

diverse service requirements of various applications. In this paper, a spectrum decision framework is proposed to

determine a set of spectrum bands by considering the application requirements as well as the dynamic nature of spectrum

bands. To this end, first, each spectrum is characterized by jointly considering primary user activity and spectrum sensing

operations. Based on this, a minimum variancebased spectrum decision is proposed for real-time applications, which

minimizes the capacity variance of the decided spectrum bands subject to the capacity constraints. For best-effort

applications, a maximum capacity-based spectrum decision is proposed where spectrum bands are decided to maximize

the total network capacity. Moreover, a dynamic resource management scheme is developed to coordinate the spectrum

decision adaptively dependent on the time-varying cognitive radio network capacity. Simulation results show that the

proposed methods provide efficient bandwidth utilization while satisfying service requirements.

07 Adaptive Location-Oriented Content Delivery in Delay-Sensitive Pervasive Applications

In this paper, we introduce a delay-sensitive service that involves transmitting large amounts of location-based data

to nodes at multiple locations. Given a limited amount of access points (APs) and an abundance of service requests

that result from the nodes moving around, a typical content delivery service would inevitably introduce considerable

delay. To solve this problem, we analyze the movement pattern of mobile nodes and approximate it as a semi-Markov

process. Based on this model, we explore different components of the underlying service delay and propose that

APs should use a multicast strategy to minimize the queuing delay component. Furthermore, we demonstrate the

feasibility of employing nodes, which already have their own local copies of location-relevant data, to relay such data

to other nodes by employing one or multiple communication channels. Lastly, we examine the resulting algorithms

and study their performance relative to baseline content-delivery schemes through simulations.

08 An Improved Geocast for Mobile Ad Hoc Networks

Geographic addressing of packets within mobile ad hoc networks enables novel applications, including hard real-time

engagement simulation in military training systems, geographic command and control functions in training and emergency

communications, and commercial messaging applications as well. The most scalable implementation of geoaddressing is

via a geocast protocol, where nodes selectively retransmit packets based on local decision rules. Well-designed

retransmission heuristics yield scalable geographic flooding that outperforms alternative geoaddressing approaches.

However, previous geocast implementations, while effective, fall into two categories. Approaches based on flooding are

unscalable due to the high load they generate. Scalable approaches, on the other hand, have trouble in complex

environments, lacking sufficient intelligence about the necessary directionality of packet flow. The present paper defines a

novel geocast heuristic, the Center Distance with Priority (CD-P) Heuristic, which both significantly improves on reliability

3



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


of existing scalable geocasts and yet also remains scalable as scenario complexity increases. This paper describes the new

technique as well as an evaluation study comparing it to previous approaches.

09 Analysis of Best Channel Feedback and Its Adaptive Algorithms for Multicarrier Wireless Data Systems

Multiuser diversity techniques are used in multicarrier data systems to enhance downlink cell throughput. This

requires downlink channel information from the users that is opportunistically used by a base station to send data to

the users with good channel condition. Channel feedback from the user to the base station incurs high overhead

especially when many users are in the cell and each user needs to report channel information over multiple

channels, as in OFDMA systems. To reduce the quantity of feedback information without significant throughput

degradation, a practical strategy is to deliver feedback on a partial set of channels with the best channel quality. We

call it best feedback, and this reporting scheme carried out for best four or five among 24 channels has been already

adopted in the IEEE 802.16e standard. Considering real feedback conditions, we investigate the performance of a

best feedback scheme and derive the optimal number of channels for which information needs to be fed back to keep

the throughput gap (compared to a full feedback scheme) within a target margin. From the optimal condition, we

propose an adaptive best feedback algorithm, where the number of reported channels is adjusted to adapt to the

number of users in the cell. We also propose an adjusted periodic feedback algorithm, where users are divided into

groups and scheduling is carried out group by group, so a user can report feedback information when his group is

scheduled, thereby reducing the frequency of feedback transmission. To support differentiated performance, we

further propose heterogeneous feedback algorithms where users are divided into heterogeneous groups, each with a

different group size or a different feedback period. Numerical results validate our analysis and provide meaningful

insights into the design of various channel feedback schemes.

10 Anticollision Protocols for Single-Reader RFID Systems: Temporal Analysis and Optimization

One of the major challenges in the use of Radio Frequency-based Identification (RFID) on a large scale is the ability to read

a large number of tags quickly. Central to solving this problem is resolving collisions that occur when multiple tags reply to

the query of a reader. To this purpose, several MAC protocols for passive RFID systems have been proposed. These

typically build on traditional MAC schemes, such as aloha and tree-based protocols. In this paper, we propose a new

performance metric by which to judge these anticollision protocols: time system efficiency. This metric provides a direct

measure of the time taken to read a group of tags. We then evaluate a set of well-known RFID MAC protocols in light of this

metric. Based on the insights gained, we propose a new anticollision protocol, and show that it significantly outperforms

previously proposed mechanisms.

11 Autonomous Deployment of Heterogeneous Mobile Sensors

In this paper, we address the problem of deploying heterogeneous mobile sensors over a target area. Traditional

approaches to mobile sensor deployment are specifically designed for homogeneous networks. Nevertheless,

network and device homogeneity is an unrealistic assumption in most practical scenarios, and previous approaches

fail when adopted in heterogeneous operative settings. For this reason, we introduce VorLag, a generalization of the

Voronoi-based approach which exploits the Laguerre geometry. We theoretically prove the appropriateness of our

4



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


proposal to the management of heterogeneous networks. In addition, we demonstrate that VorLag can be extended

to deal with dynamically generated events or uneven energy depletion due to communications. Finally, by means of

simulations, we show that VorLag provides a very stable sensor behavior, with fast and guaranteed termination and

moderate energy consumption. We also show that VorLag performs better than its traditional counterpart and other

methods based on virtual forces.

12 Breath: An Adaptive Protocol for Industrial Control Applications Using Wireless Sensor Networks

An energy-efficient, reliable and timely data transmission is essential for Wireless Sensor Networks (WSNs) employed in

scenarios where plant information must be available for control applications. To reach a maximum efficiency, cross-layer

interaction is a major design paradigm to exploit the complex interaction among the layers of the protocol stack. This is

challenging because latency, reliability, and energy are at odds, and resource-constrained nodes support only simple

algorithms. In this paper, the novel protocol Breath is proposed for control applications. Breath is designed for WSNs

where nodes attached to plants must transmit information via multihop routing to a sink. Breath ensures a desired packet

delivery and delay probabilities while minimizing the energy consumption of the network. The protocol is based on

randomized routing, medium access control, and duty-cycling jointly optimized for energy efficiency. The design approach

relies on a constrained optimization problem, whereby the objective function is the energy consumption and the

constraints are the packet reliability and delay. The challenging part is the modeling of the interactions among the layers by

simple expressions of adequate accuracy, which are then used for the optimization by in-network processing. The optimal

working point of the protocol is achieved by a simple algorithm, which adapts to traffic variations and channel conditions

with negligible overhead. The protocol has been implemented and experimentally evaluated on a testbed with off-the-shelf

wireless sensor nodes, and it has been compared with a standard IEEE 802.15.4 solution. Analytical and experimental

results show that Breath is tunable and meets reliability and delay requirements. Breath exhibits a good distribution of the

working load, thus ensuring a long lifetime of the network. Therefore, Breath is a good candidate for efficient, reliable, and

timely data gathering for control applications.

13 Channel-Aware Routing in MANETs with Route Handoff

In wireless mobile ad hoc networks (MANETs), packet transmission is impaired by radio link fluctuations. This paper

proposes a novel channel adaptive routing protocol which extends the Ad hoc On-Demand Multipath Distance Vector

(AOMDV) routing protocol to accommodate channel fading. Specifically, the proposed Channel-Aware AOMDV (CA-

AOMDV) uses the channel average nonfading duration as a routing metric to select stable links for path discovery,

and applies a preemptive handoff strategy to maintain reliable connections by exploiting channel state information.

Using the same information, paths can be reused when they become available again, rather than being discarded. We

provide new theoretical results for the downtime and lifetime of a live-die-live multiple path system, as well as

detailed theoretical expressions for common network performance measures, providing useful insights into the

differences in performance between CA-AOMDV and AOMDV. Simulation and theoretical results show that CA-

AOMDV has greatly improved network performance over AOMDV.

14 Cognitive Medium Access: Exploration, Exploitation, and Competition

5



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


This paper considers the design of efficient strategies that allow cognitive users to choose frequency bands to sense and

access among multiple bands with unknown parameters. First, the scenario in which a single cognitive user wishes to

opportunistically exploit the availability of frequency bands is considered. By adopting tools from the classical bandit

problem, optimal as well as low complexity asymptotically optimal solutions are developed. Next, the multiple cognitive

user scenario is considered. The situation in which the availability probability of each channel is known is first considered.

An optimal symmetric strategy that maximizes the total throughput of the cognitive users is developed. To avoid the

possible selfish behavior of the cognitive users, a game-theoretic model is then developed. The performance of both

models is characterized analytically. Then, the situation in which the availability probability of each channel is unknown a

priori is considered. Low-complexity medium access protocols, which strike an optimal balance between exploration and

exploitation in such competitive environments, are developed. The operating points of these low-complexity protocols are

shown to converge to those of the scenario in which the availability probabilities are known. Finally, numerical results are

provided to illustrate the impact of sensing errors and other practical considerations.

15 Compatibility between Three Well-Known Broadcast Tree Construction Algorithms and Various Metrics

Broadcast routing is a critical component in the routing design. While there are plenty of routing metrics and

broadcast routing schemes in current literature, it remains an unsolved problem as to which metrics are compatible

with a specific broadcast routing scheme. In particular, in the wireless broadcast routing context where transmission

has an inherent broadcast property, there is a potential danger of incompatible combination of broadcast routing

algorithms and metrics. This paper shows that different broadcast routing algorithms have different requirements on

the properties of broadcast routing metrics. The metric properties for broadcast routing algorithms in both

undirected network topologies and directed network topologies are developed and proved. They are successfully

used to verify the compatibility between broadcast routing metrics and broadcast routing algorithms.

16 Context-Based Network Estimation for Energy-Efficient Ubiquitous Wireless Connectivity

Context information brings new opportunities for efficient and effective system resource management of mobile devices. In

this work, we focus on the use of context information to achieve energy-efficient, ubiquitous wireless connectivity. Our

field-collected data show that the energy cost of network interfaces poses a great challenge to ubiquitous connectivity,

despite decent availability of cellular networks. We propose to leverage the complementary strengths of Wi-Fi and cellular

interfaces by automatically selecting the most efficient one based on context information. We formulate the selection of

wireless interfaces as a statistical decision problem. The challenge is to accurately estimate Wi-Fi network conditions

without powering up the network interface. We explore the use of different context information, including time, history,

cellular network conditions, and device motion, to statistically estimate Wi-Fi network conditions with negligible overhead.

We evaluate several context-based algorithms for the estimation and prediction of current and future network conditions.

Simulations using field-collected traces show that our network estimation algorithms can improve the average battery

lifetime of a commercial mobile phone for an ECG reporting application by 40 percent, very close to the estimated

theoretical upper bound of 42 percent. Furthermore, our most effective algorithm can predict Wi-Fi availability for one and

ten hours into the future with 95 and 90 percent accuracy, respectively.

6



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


17 Cross-Layer Optimization for Multimedia Transport over Multicode CDMA Networks

Most previous work on code division multiple access (CDMA) considers the bit error ratio (BER) at the physical layer

and the frame drop ratio (FDR) at the medium access control layer separately. However, a better system

performance, e.g., in terms of a lower overall frame loss ratio (FLR), can be achieved if BER and FDR are jointly

optimized. In this paper, we propose a cross-layer optimization scheme called traffic-adaptive scheme for multicode

CDMA operating over a time division multiple access (TDMA) channel. Based on the traffic condition and buffer

status, this scheme employs a Markov Decision Process (MDP) to determine the optimal value of the maximum

number of simultaneous data frames that can be transmitted in each time slot of a TDMA frame so as to minimize the

overall FLR of the system. To facilitate implementation, we also propose an approximation scheme named the

rateadaptive scheme to reduce the computation cost. Simulation and analytical results show that both the traffic-

adaptive scheme and rate-adaptive scheme can significantly reduce FLR, increase the system throughput, and

optimize the packet access delay of the system. Furthermore, the rate-adaptive scheme can achieve a performance

close to the traffic-adaptive scheme when the traffic load in the system is high.

18 Data Delivery Properties of Human Contact Networks

Pocket Switched Networks take advantage of social contacts to opportunistically create data paths over time. This work

employs empirical traces to examine the effect of the human contact process on data delivery in such networks. The

contact occurrence distribution is found to be highly uneven: contacts between a few node pairs occur too frequently,

leading to inadequate mixing in the network, while the majority of contacts occur rarely, but are essential for global

connectivity. This distribution of contacts leads to a significant variation in the fraction of node pairs that can be connected

over time windows of similar duration. Good time windows tend to have a large clique of nodes that can all reach each

other. It is shown that the clustering coefficient of the contact graph over a time window is a good predictor of achievable

connectivity. We then examine all successful paths found by flooding and show that though delivery times vary widely,

randomly sampling a small number of paths between each source and destination is sufficient to yield a delivery time

distribution close to that of flooding over all paths. This result suggests that the rate at which the network can deliver data

is remarkably robust to path failures.

19 Design and Performance Analysis of Mobility Management Schemes Based on Pointer Forwarding for Wireless Mesh Networks

We propose efficient mobility management schemes based on pointer forwarding for wireless mesh networks

(WMNs) with the objective to reduce the overall network traffic incurred by mobility management and packet delivery.

The proposed schemes are per-user-based, i.e., the optimal threshold of the forwarding chain length that minimizes

the overall network traffic is dynamically determined for each individual mobile user, based on the user’s specific

mobility and service patterns. We develop analytical models based on stochastic Petri nets to evaluate the

performance of the proposed schemes. We demonstrate that there exists an optimal threshold of the forwarding

chain length, given a set of parameters characterizing the specific mobility and service patterns of a mobile user. We

also demonstrate that our schemes yield significantly better performance than schemes that apply a static threshold

to all mobile users. A comparative analysis shows that our pointer forwarding schemes outperform routing-based

7



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


mobility management protocols for WMNs, especially for mobile Internet applications characterized by large traffic

asymmetry for which the downlink packet arrival rate is much higher than the uplink packet arrival rate.

20 Design and Performance of an Optimal Inertial Power Harvester for Human-Powered Devices

We present an empirical study of the long-term practicality of using human motion to generate operating power for

bodymounted consumer electronics and health sensors. We have collected a large continuous acceleration data set from

eight experimental subjects going about their normal daily routine for three days each. Each subject is instrumented with a

data collection apparatus that simultaneously logs 3-axis, 80 Hz acceleration data from six body locations. We use this data

set to optimize a firstprinciples physical model of the commonly used velocity damped resonant generator (VDRG) by

selecting physical parameters such as resonant frequency and damping coefficient to maximize the harvested power. Our

results show that with reasonable assumptions on size, mass, placement, and efficiency of VDRG harvesters, most body-

mounted wireless sensors and even some consumer electronics devices can be powered continuously and indefinitely

from everyday motion. We have optimized the power harvesters for each individual and for each body location. In addition,

we present the potential of designing a damping- and frequency-tunable power harvester that could mitigate the power

reduction of a generator generalized for “average” subjects. We present the full details on the collection of the acceleration

data sets, the development of the VDRG model, and a numerical simulator, and discuss some of the future challenges that

remain in this promising field of research.

21 Discriminant Minimization Search for Large-Scale RF-Based Localization Systems

In large-scale fingerprinting localization systems, fine-grained location estimation and quick location determination

are conflicting concerns. To achieve finer grained localization, we have to collect signal patterns at a larger number

of training locations. However, this will incur higher computation cost during the pattern-matching process. In this

paper, we propose a novel discriminant minimization search (DMS)-based localization methodology. Continuous and

differentiable discriminant functions are designed to extract the spatial correlation of signal patterns at training

locations. The advantages of the DMS-based methodology are threefold. First, with through slope of discriminant

functions, the exhaustive pattern-matching process can be replaced by an optimization search process, which could

be done by a few quick jumps. Second, the continuity of the discriminant functions helps predict signal patterns at

untrained locations so as to achieve finer grained localization. Third, the large amount of training data can be

compressed into some functions that can be represented by a few parameters. Therefore, the storage space required

for localization can be significantly reduced. To realize this methodology, two algorithms, namely, Newton-PL and

Newton-INT, are designed based on the concept of gradient descent search. Simulation and experiment studies show

that our algorithms do provide finer grained localization and incur less computation cost.

8



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


22 Distributed Fault-Tolerant Quality of Wireless Networks

A mobile ad hoc network (MANET) consists of a group of communicating hosts that form an arbitrary network topology by

means of any of several wireless communication media. MANET communications represent a diversification in

communication technology necessary to solve the stringent end-to-end requirements of QoS-based communication

networks. Of the many challenges in this complex distributed system, the problem of routing based on a predefined set of

customer preferences, critical to guaranteeing quality-of-service, is the focus of this research. Specifically, this paper

modifies a cluster-based QoS routing algorithm for mobile ad hoc networks with the aim of providing fault tolerance, which

is a critical feature in providing QoS in the link failure-prone environment of mobile networks. Performance of this new

fault-tolerant cluster-based QoS wireless algorithm is evaluated according to failure recovery time, dropped packets,

throughput, and sustained flow bandwidth via simulations involving node failure scenarios along QoS paths.

23 Distributed Multi-Interface Multichannel Random Access Using Convex Optimization

The aggregate capacity of wireless ad hoc networks can be increased substantially if each node is equipped with

multiple network interface cards (NICs) and each NIC operates on a distinct frequency channel. Most of the recently

proposed channel assignment algorithms are based on combinatorial techniques. Combinatorial channel assignment

schemes may sometimes result in computationally complicated algorithms as well as inefficient utilization of the

available frequency spectrum. In this paper, we analytically model channel and interface assignment problems as

tractable continuous optimization problems within the framework of network utility maximization (NUM). In particular,

the link data rate models for both single-channel reception and multichannel reception scenarios are derived. The

assignment of both nonoverlapped and partially overlapped channels is also considered. We then propose two

distributed multi-interface multichannel random access (DMMRA) algorithms for single-channel reception and

multichannel reception scenarios. The DMMRA algorithms are fast, distributed, and easy to implement. Each

algorithm solves the formulated NUM problem for each scenario. DMMRA requires each node to only iteratively solve

a local, myopic, and convex optimization problem. Convergence and optimality properties of our algorithms are

studied analytically. Simulation results show that our proposed algorithms significantly outperform utility-optimal

combinatorial channel assignment algorithms in terms of both achieved network utility and throughput.

24 Dynamic Conflict-Free Transmission Scheduling for Sensor Network Queries

With the emergence of high data rate sensor network applications, there is an increasing demand for high-performance

query services. To meet this challenge, we propose Dynamic Conflict-free Query Scheduling (DCQS), a novel scheduling

technique for queries in wireless sensor networks. In contrast to earlier TDMA protocols designed for general-purpose

workloads, DCQS is specifically designed for query services in wireless sensor networks. DCQS has several unique

features. First, it optimizes the query performance through conflict-free transmission scheduling based on the temporal

properties of queries in wireless sensor networks. Second, it can adapt to workload changes without explicitly

reconstructing the transmission schedule. Furthermore, DCQS also provides predictable performance in terms of the

maximum achievable query rate. We provide an analytical capacity bound for DCQS that enables DCQS to handle overload

9



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


through rate control. NS2 simulations demonstrate that DCQS significantly outperforms a representative TDMA protocol

(DRAND) and 802.11b in terms of query latency and throughput.

25 Dynamic Time Slot Partitioning for Multimedia Transmission in Two-Hop Cellular Networks

In recent years, there has been an exponential increase in the number of mobile phone users. In addition, a

significant growth in the demand for high-rate multimedia services over wireless networks, such as video

conferencing, multimedia streaming, etc., was noted. Different solutions were proposed to support high-quality high

data rate delivery to mobile users, including resource allocation techniques for packet-radio-based next generation

cellular networks. In this paper, an efficient time slot allocation method—Dynamic Time Slot Partitioning (DTSP)

algorithm based on statistical multiplexing is proposed for a two-hop cellular architecture. In DTSP, the available

bandwidth resources are increased by partitioning each time slot into several minislots wherein different numbers of

minislots are allocated to different users. The DTSP algorithm is based on asynchronous time-division multiplexing,

wherein users with variable number of packets in their buffers can transmit data sequentially without any loss in the

overall available resources. The key advantage of DTSP is that it can flexibly adapt to different quality of service

requirements, especially when combined with adaptive modulation. It has been observed that the system capacity

achieved by the DTSP algorithm in the downlink mode using adaptive modulation is up to 41 percent higher than

when existing solutions are employed. In addition, DTSP results in significantly lower time for data transmission than

the state-of-the-art region and time partitioning techniques.

26 Effective Scheduling in Infrastructure-Based Cognitive Radio Networks

In this paper, we investigate a joint scheduling and power control for an infrastructure-based cognitive radio network (CRN)

in coexistence with a cellular primary radio network (PRN). The PRN uses a set of licensed nonoverlapping orthogonal

frequency channels for transmission. This set of channels is also accessed in an opportunistic manner by a set of cognitive

radio base stations (CR-BSs) to support secondary users (SUs). The problem is formulated to maximize the spectrum

utilization of SUs without causing excessive interference to active primary users (PUs) of the PRN. In addition, all the

serviced SUs must meet a certain Quality of Service (QoS), such as satisfying a predefined signal to interference noise ratio

(SINR). A centralized solution for joint scheduling and power control is derived to make the global accessing decision for all

unserved SUs. With the assumption that the knowledge of all subscribers is available, a coordinator of the CRN can use the

joint scheduling and power control algorithm to maximize the spectrum utilization of serviced SUs by solving a mixed-

integer linear programming (MILP) with an NP-hard complexity. To avoid the NP-hard complexity, we propose a suboptimal

heuristic greedy algorithm that can be obtained at a much lower complexity based on the coloring interference graph

among unserved SUs effected by serviced SUs and active PUs. Its superior performance over the existing algorithms is

demonstrated through simulations.

27 Efficient Data Collection in Wireless Sensor Networks with Path-Constrained Mobile Sinks

Recent work has shown that sink mobility along a constrained path can improve the energy efficiency in wireless

sensor networks. However, due to the path constraint, a mobile sink with constant speed has limited communication

time to collect data from the sensor nodes deployed randomly. This poses significant challenges in jointly improving

10



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the amount of data collected and reducing the energy consumption. To address this issue, we propose a novel data

collection scheme, called the Maximum Amount Shortest Path (MASP), that increases network throughput as well as

conserves energy by optimizing the assignment of sensor nodes. MASP is formulated as an integer linear

programming problem and then solved with the help of a genetic algorithm. A two-phase communication protocol

based on zone partition is designed to implement the MASP scheme. We also develop a practical distributed

approximate algorithm to solve the MASP problem. In addition, the impact of different overlapping time partition

methods is studied. The proposed algorithms and protocols are validated through simulation experiments using

OMNET++.

28 Efficient Location Training Protocols for Heterogeneous Sensor and Actor Networks

In this work, we consider a large-scale geographic area populated by tiny sensors and some more powerful devices called

actors, authorized to organize the sensors in their vicinity into short-lived, actor-centric sensor networks. The tiny sensors

run on miniature nonrechargeable batteries, are anonymous, and are unaware of their location. The sensors differ in their

ability to dynamically alter their sleep times. Indeed, the periodic sensors have sleep periods of predefined lengths,

established at fabrication time; by contrast, the free sensors can dynamically alter their sleep periods, under program

control. The main contribution of this work is to propose an energy-efficient location training protocol for heterogeneous

actor-centric sensor networks where the sensors acquire coarse-grain location awareness with respect to the actor in their

vicinity. Our theoretical analysis, confirmed by experimental evaluation, shows that the proposed protocol outperforms the

best previously known location training protocols in terms of the number of sleep/awake transitions, overall sensor awake

time, and energy consumption.

29 Endpoint-Based Call Admission Control and Resource Management for VoWLAN

This paper examines two specific aspects of resource management in Wireless Local Area Networks (WLANs)—Call

Admission Control (CAC) and handling of Link Adaptation (LA) events. A self-consistent system to manage these for

Voice over Internet Protocol (VoIP) over an IEEE 802.11 WLAN is presented. The proposed CAC scheme is based on

the Endpoint Admission Control (EAC) paradigm, where the endpoints probe the network to determine if the call can

be supported with acceptable Quality of Service (QoS). The proposed scheme was evaluated on an experimental

testbed and test results show that correct admission decisions were made under various network configurations.

The scheme also determines if LA has resulted in the system becoming congested and, if so, the voice codec of the

handset which has undergone LA is adapted so as to restore the system to its earlier state, thereby alleviating the

congestion. The proposed scheme was evaluated on the experimental testbed and test results show that the codec

adaptation scheme was very effective at overcoming the effects of LA for VoIP over WLAN.

11



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Trichy


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Kollam




Contact : 91474 2723622.


30 Expected Routing Overhead for Location Service in MANETs under Flat Geographic Routing

In this work, we consider a large-scale geographic area populated by tiny sensors and some more powerful devices called

actors, authorized to organize the sensors in their vicinity into short-lived, actor-centric sensor networks. The tiny sensors

run on miniature nonrechargeable batteries, are anonymous, and are unaware of their location. The sensors differ in their

ability to dynamically alter their sleep times. Indeed, the periodic sensors have sleep periods of predefined lengths,

established at fabrication time; by contrast, the free sensors can dynamically alter their sleep periods, under program

control. The main contribution of this work is to propose an energy-efficient location training protocol for heterogeneous

actor-centric sensor networks where the sensors acquire coarse-grain location awareness with respect to the actor in their

vicinity. Our theoretical analysis, confirmed by experimental evaluation, shows that the proposed protocol outperforms the

best previously known location training protocols in terms of the number of sleep/awake transitions, overall sensor awake

time, and energy consumption.

31 Explicit Congestion Control Algorithms for Time Varying Capacity Media

Explicit congestion control (XCC) is emerging as one potential solution for overcoming limitations inherent to the

current TCP algorithm, characterized by unstable throughput, high queuing delay, RTT-limited fairness, and a static

dynamic range that does not scale well to high bandwidth delay product networks. In XCC, routers provide multibit

feedback to sources, which, in turn, adapt throughput more accurately to the path bandwidth with potentially faster

convergence times. Such systems, however, require precise knowledge of link capacity for efficient operation. In the

presence of variable-capacity media, e.g., 802.11, such information is not entirely obvious or may be difficult to

extract. We explore three possible algorithms for XCC which retain efficiency under such conditions by inferring

available bandwidth from queue dynamics and test them through simulations with two relevant XCC protocols: XCP

and RCP. Additionally, preliminary results from an experimental implementation based on XCP are presented. Finally,

we compare our proposals with TCP and show how such algorithms outperform it in terms of efficiency, stability,

queuing delay, and flowrate fairness.

32 Fast Detection of Mobile Replica Node Attacks in Wireless Sensor Networks Using Sequential Hypothesis Testing Jun- Won

Due to the unattended nature of wireless sensor networks, an adversary can capture and compromise sensor nodes, make

replicas of them, and then mount a variety of attacks with these replicas. These replica node attacks are dangerous

because they allow the attacker to leverage the compromise of a few nodes to exert control over much of the network.

Several replica node detection schemes have been proposed in the literature to defend against such attacks in static

sensor networks. However, these schemes rely on fixed sensor locations and hence do not work in mobile sensor

networks, where sensors are expected to move. In this work, we propose a fast and effective mobile replica node detection

scheme using the Sequential Probability Ratio Test. To the best of our knowledge, this is the first work to tackle the

problem of replica node attacks in mobile sensor networks. We show analytically and through simulation experiments that

our scheme detects mobile replicas in an efficient and robust manner at the cost of reasonable overheads.

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Trichy


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33 Flexible Broadcasting of Scalable Video Streams to Heterogeneous Mobile Devices

We study the scalable video broadcasting problem in mobile TV broadcast networks, where each TV channel is

encoded into a scalable video stream with multiple layers, and several TV channels are concurrently broadcast over

a shared air medium to many mobile devices with heterogeneous resources. Our goal is to encapsulate and

broadcast video streams encoded in scalable manner to enable heterogeneous mobile devices to render the most

appropriate video substreams while achieving high energy saving and low channel switching delay. The appropriate

streams depend on the device capability and the target energy consumption level. We propose two new broadcast

schemes, which are flexible in the sense that they allow diverse bit rates among layers of the same stream. Such

flexibility enables videos to be optimally encoded in terms of coding efficiency, and allows the coded video streams

to be better matched with the capability of mobile devices. We analyze the performance of the proposed broadcast

schemes. In addition, we have implemented the proposed schemes in a real mobile TV testbed to show their

practicality and efficiency. Our extensive experiments confirm that the proposed schemes enable energy saving

differentiation: between 75 and 95 percent were observed. Moreover, one of the schemes achieves low channel

switching delays: 200 msec is possible with typical system parameters.

34 Integration Gain of Heterogeneous WiFi/WiMAX Networks

We study the integrated WiFi/WiMAX networks, where users are equipped with dual-radio interfaces that can connect to

either a WiFi or a WiMAX network. Previous research on integrated heterogeneous networks (e.g., WiFi/cellular) usually

considers one network as the main and the other as the auxiliary. The performance of the integrated network is compared

with the “main” network. The gain is apparently due to the additional resources from the auxiliary network. In this study, we

are interested in integration gain that comes from the better utilization of the resource rather than the increase of the

resource. The heterogeneity of the two networks is the fundamental reason for the integration gain. To quantify it, we

design a generic framework that supports different performance objectives. We focus on the max-min throughput fairness

in this work and also briefly cover the proportional fairness metric. We first prove that it is NP-hard to achieve integral max-

min throughput fairness, then propose a heuristic algorithm, which provides twoapproximation to the optimal fractional

solution. Simulation results demonstrate significant integration gain from three sources, namely, spatial multiplexing,

multinetwork diversity, and multiuser diversity. For the proportional fairness metric, we derive the formulation and propose

a heuristic algorithm, which shows satisfactory performance when compared with the optimal solution.

35 Interference-Aware Routing in Wireless Multihop Networks

Interference is an inherent characteristic of wireless (multihop) communications. Adding interference-awareness to

important control functions, e.g., routing, could significantly enhance the overall network performance. Despite some

initial efforts, it is not yet clearly understood how to best capture the effects of interference in routing protocol

design. Most existing proposals aim at inferring its effect by actively probing the link. However, active probe

measurements impose an overhead and may often misrepresent the link quality due to their interaction with other

networking functions. Therefore, in this paper we follow a different approach and: 1) propose a simple yet accurate

analytical model for the effect of interference on data reception probability, based only on passive measurements

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and information locally available at the node; 2) use this model to design an efficient interference-aware routing

protocol that performs as well as probing-based protocols, yet avoids all pitfalls related to active probe

measurements. To validate our proposal, we have performed experiments in a real testbed, setup in our indoor office

environment. We show that the analytical predictions of our interference model exhibit good match with both

experimental results as well as more complicated analytical models proposed in related literature. Furthermore, we

demonstrate that a simple probeless routing protocol based on our model performs at least as good as well-known

probe-based routing protocols in a large set of experiments including both intraflow and interflow.

36 Localization of Mobile Nodes in Wireless Networks with Correlated in Time Measurement Noise

Wireless sensor networks are an inherent part of decision making, object tracking, and location awareness systems. This

work is focused on simultaneous localization of mobile nodes based on received signal strength indicators (RSSIs) with

correlated in time measurement noises. Two approaches to deal with the correlated measurement noises are proposed in

the framework of auxiliary particle filtering: with a noise augmented state vector and the second approach implements

noise decorrelation. The performance of the two proposed multimodel auxiliary particle filters (MM AUX-PFs) is validated

over simulated and real RSSIs and high localization accuracy is demonstrated.

37 MAC Layer Throughput Estimation in Impulse-Radio UWB Networks

The inherent channel characteristics of impulse-based UWB networks affect the MAC layer performance significantly.

Most previous studies on evaluating MAC protocols are based on prolonged simulations and do not account for the

multiple access interference due to multipath delay spread. In this work, we develop CTU, an analytical framework for

Capturing the Throughput dependencies in UWB networks, while taking into account the PHY layer effects. The key

attributes of CTU are: 1) It is modular; it can be easily modified to provide a basis for evaluating a wide range of MAC

protocols for impulse-based UWB networks. The only requirements are that the MAC protocol under study be based

on time-hopping and the modulation scheme be pulse position modulation; these are common design decisions in

UWB networks. 2) It considers the channel characteristics in addition to MAC layer effects; CTU correlates

probabilistically the multipath delay profile of the channel with the packet error rate. We employ CTU to evaluate the

performance of different generic medium access procedure. We compare the results with those from extensive

simulations and show the high accuracy of CTU. We use CTU to assess the impact of various system parameters on

the MAC layer performance; we make several interesting observations that are discussed in depth.

38 MAP: Multiauctioneer Progressive Auction for Dynamic Spectrum Access

Cognitive radio (CR) is a promising paradigm to achieve efficient utilization of the limited spectrum resource by allowing

the unlicensed users to access the licensed spectrum, and dynamic spectrum access (DSA) is one of the fundamental

functions of CR networks. Market-driven spectrum auction has been recognized as an effective way to achieve DSA. In

spectrum auction, the primary spectrum owners (POs) act as auctioneers who are willing to sell idle spectrum bands for

additional revenue, and the secondary users (SUs) act as bidders who are willing to buy spectrum bands from POs for their

services. However, conventional spectrum auction designs are restricted within the scenario of single auctioneer. In this

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paper, we study the spectrum auction with multiple auctioneers and multiple bidders, which is more realistic for practical

CR networks. We propose MAP, a Multiauctioneer Progressive auction mechanism, in which each auctioneer systematically

raises the trading price and each bidder subsequently chooses one auctioneer for bidding. The equilibrium is defined as

the state that no auctioneer and bidder would like to change his decision. We show analytically that MAP converges to the

equilibrium with maximum spectrum utilization of the whole system. We further analyze the incentive for POs and SUs

joining the auction and accepting the auction result. Simulation results show that MAP well converges to the equilibrium,

and the spectrum utilization is arbitrary closed to the global optimal solution according to the length of step.

39 Minimum Bandwidth Reservations for Periodic Streams in Wireless Real-Time Systems

Reservation-based (as opposed to contention-based) channel access in WLANs provides predictable and

deterministic transmission and is therefore able to provide timeliness guarantees for wireless and embedded real-

time applications. Also, reservation-based channel access is energy-efficient since a wireless adaptor is powered on

only during its exclusive channel access times. While scheduling for Quality of Service at the central authority (e.g.,

base station) has received extensive attention, the problem of determining the actual resource requirements of an

individual node in a wireless real-time system has been largely ignored. This work aims at finding the minimum

channel bandwidth reservation that meets the real-time constraints of all periodic streams of a given node. Keeping

the bandwidth reservation of a node to a minimum leads to reduced energy and resource requirements and leaves

more bandwidth for future reservations by other nodes. To obtain a solution to the minimum bandwidth reservation

problem, we transform it to a generic uniprocessor task schedulability problem, which is then addressed using a

generic algorithm. This algorithm works for a subclass of priority-driven packet scheduling policies, including three

common ones: fixed-priority, EDF, and FIFO. Moreover, we then specialize the generic algorithm to these three

policies according to their specific characteristics. Their computation complexities and bandwidth reservation

efficiencies are evaluated and guidelines for choosing scheduling policies and stream parameters are presented.

40 Mobile Sampling of Sensor Field Data Using Controlled Broadcast

Mobile objects can be used to gather samples from a sensor field. Civilian vehicles or even human beings equipped with

proper wireless communication devices can be used as mobile sinks that retrieve sensor-data from sampling points within

a large sensor field. A key challenge is how to gather the sensor data in a manner that is energy efficient with respect to the

sensor nodes that serve as sources of the sensor data. In this paper, an algorithmic technique called Band-based

Directional Broadcast is introduced to control the direction of broadcasts that originate from sensor nodes. The goal is to

direct each broadcast of sensor data toward the mobile sink, thus reducing costly forwarding of sensor data packets. The

technique is studied by simulations that consider energy consumption and data deliverability.

41 Mobility Tracking Based on Autoregressive Models

We propose an integrated scheme for tracking the mobility of a user based on autoregressive models that accurately

capture the characteristics of realistic user movements in wireless networks. The mobility parameters are obtained

from training data by computing Minimum Mean Squared Error (MMSE) estimates. Estimation of the mobility state,

which incorporates the position, velocity, and acceleration of the mobile station, is accomplished via an extended

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Trichy


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Kalman filter using signal measurements from the wireless network. By combining mobility parameter and state

estimation in an integrated framework, we obtain an efficient and accurate real-time mobility tracking scheme that

can be applied in a variety of wireless networking applications. We consider two variants of an autoregressive

mobility model in our study and validate the proposed mobility tracking scheme using mobile trajectories collected

from drive test data. Our simulation results validate the accuracy of the proposed tracking scheme even when only a

small number of data samples is available for initial training.

42 Modeling and Improving TCP Performance over Cellular Link with Variable Bandwidth

To facilitate a viable evolution of cellular networks toward extensive packet data traffic, the High Speed Downlink Packet

Access (HSDPA) technology is introduced. The various link adaptation techniques employed by HSDPA augment the

bandwidth variation, which is identified as one of the most important factors resulting in the deterioration of TCP

performance. In this paper, we firstly build an analytical model of TCP throughput to explain why the bandwidth variation

degrades the TCP performance. Subsequently, a split-connection Window Adaptation TCP Proxy is proposed to improve

the TCP throughput in HSDPA networks. To use the precious cellular link resources sufficiently, the length of the queue in

Node-B is intentionally kept around the reference value through adaptively adjusting the sending window size of TCP proxy

based on the dynamic values of varying bandwidth. Since both the disturbance caused by bandwidth variation and the

feedback delay are prone to lead an unstable queue system, the robust sliding mode variable structure control theory is

employed to design the proper control law to weaken the impact of noise and delay on the stability of the queue system in

Node-B. The theoretical analysis and the enhanced scheme are verified through simulation experiments. The simulation

results show that our TCP proxy is able to resist against bandwidth oscillation and improve the cellular link utilization.

43 Multicast Throughput for Hybrid Wireless Networks under Gaussian Channel Model

We study the multicast capacity for hybrid wireless networks consisting of ordinary ad hoc nodes and base stations

under Gaussian Channel model, which generalizes both the unicast and broadcast capacities for hybrid wireless

networks. Assume that all ordinary ad hoc nodes transmit at a constant power P, and the power decays along the

path, with attenuation exponent alpha > 2. The data rate of a transmission is determined by the Signal to Interference

plus Noise Ratio (SINR) at the receiver as Blog(1+ SINR). The ordinary ad hoc nodes are placed in the square region

AðaÞ of area a according to a Poisson point process of intensity n=a. Then, m additional base stations (BSs) acting

as the relaying communication gateways are placed regularly in the region AðaÞ, and are connected by a high-

bandwidth wired network. Let a ¼ n and a ¼ 1, we construct the hybrid extended network (HEN) and hybrid dense

network (HDN), respectively. We choose randomly and independently ns ordinary ad hoc nodes to be the sources of

multicast sessions. We assume that each multicast session has nd randomly chosen terminals. Three broad

categories of multicast strategies are proposed. The first one is the hybrid strategy, i.e., the multihop scheme with

BS-supported, which further consists of two types of strategies called connectivity strategy and percolation strategy,

respectively. The second one is the ordinary ad hoc strategy, i.e., the multihop scheme without any BS-supported.

The third one is the classical BS-based strategy under which any communication between two ordinary ad hoc nodes

is relayed by some specific BSs. According to the different scenarios in terms of m, n, and nd, we select the optimal

scheme from the three categories of strategies, and derive the achievable multicast throughput based on the optimal

decision.

16



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Trichy


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44 OFDM-Based Common Control Channel Design for Cognitive Radio Ad Hoc Networks

Cognitive radio (CR) technology allows devices to opportunistically use the vacant portions of the licensed wireless

spectrum. However, the available spectrum changes dynamically with the primary user (PU) activity, necessitating frequent

PU sensing coordination and exchanging network topology information in a multihop CR ad hoc network. To facilitate these

tasks, an always-on, out-of-band common control channel (CCC) design is proposed that uses noncontiguous OFDM

subcarriers placed within the guard bands separating the channels of the licensed spectrum. First, the task of choosing the

OFDM-specific parameters, including the number, power, and bandwidth of the subcarriers is formulated as a feasibility

problem to ensure that the CCC does not adversely interfere with the PU operation. Second, for unicast messaging between

a given pair of users, a subset of the guard bands may be chosen, which allows an additional measure of protection for the

adjacent PU spectrum. For this, the multiarm bandit algorithm is used that allows the guard band selection to evolve over

time based on the observed interference from the PU. Results reveal that our proposed CCC ensures connectivity and

improved PU protection with a limited trade-off in data rate when compared to frequencyhopping and cluster-based CCC

schemes.

45 On the Design of Opportunistic MAC Protocols for Multihop Wireless Networks with Beamforming Antennas

Beamforming antennas promise a significant increase in the spatial reuse of the wireless medium when deployed in

multihop wireless networks. However, existing directional Medium Access Control (MAC) protocols with the default

binary exponential backoff mechanism are not capable of fully exploiting the offered potential. In this paper, we

discuss various issues involved in the design of MAC protocols specific for beamforming antennas. Based on our

discussion, we argue that the traditional binary exponential backoff mechanism limits the possible spatial reuse and

aggravates some beamforming-related problems such as deafness and headof- line blocking. To grasp the

transmission opportunities offered by beamforming antennas, we design an Opportunistic Directional MAC

(OPDMAC) protocol for multihop wireless networks. The OPDMAC protocol employs a novel backoff mechanism in

which the node is not forced to undergo idle backoff after a transmission failure but can rather take the opportunity

of transmitting other outstanding packets in other directions. This mechanism minimizes the idle waiting time and

increases the channel utilization significantly and thereby enables OPDMAC to enhance the spatial reusability of the

wireless medium and reduce the impact of the deafness problem without additional overhead. Through extensive

simulations, we demonstrate that OPDMAC enhances the performance in terms of throughput, delay, packet delivery

ratio, and fairness. To further improve its performance, we discuss and evaluate the benefits of carefully choosing

some protocol parameters instead of using the default values commonly used by other directional MAC protocols.

17



Madurai




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Trichy


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Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


46 On the Effectiveness of Monitoring for Intrusion Detection in Mobile Ad Hoc Networks

Several intrusion detection techniques (IDTs) proposed for mobile ad hoc networks rely on each node passively monitoring

the data forwarding by its next hop. This paper presents quantitative evaluations of false positives and their impact on

monitoringbased intrusion detection for ad hoc networks. Experimental results show that, even for a simple three-node

configuration, an actual ad hoc network suffers from high false positives; these results are validated by Markov and

probabilistic models. However, this false positive problem cannot be observed by simulating the same network using

popular ad hoc network simulators, such as ns-2, OPNET or Glomosim. To remedy this, a probabilistic noise generator

model is implemented in the Glomosim simulator. With this revised noise model, the simulated network exhibits the

aggregate false positive behavior similar to that of the experimental testbed. Simulations of larger (50-node) ad hoc

networks indicate that monitoring-based intrusion detection has very high false positives. These false positives can reduce

the network performance or increase the overhead. In a simple monitoring-based system where no secondary and more

accurate methods are used, the false positives impact the network performance in two ways: reduced throughput in normal

networks without attackers and inability to mitigate the effect of attacks in networks with attackers.

47 On the Information Flow Required for Tracking Control in Networks of Mobile Sensing Agents

We design controllers that permit mobile agents with distributed or networked sensing capabilities to track (follow)

desired trajectories, identify what trajectory information must be distributed to each agent for tracking, and develop

methods to minimize the communication needed for the trajectory information distribution.

48 Optimal and Efficient Graph-Based Resource Allocation Algorithms for Multiservice Frame-Based OFDMA Networks

This paper addresses the resource allocation problem in Orthogonal Frequency Division Multiple Access (OFDMA)-based

wireless networks. The resource allocation problem is posed as an optimization problem with individual user constraints.

This formulation provides a special structure that lends to efficient solution of the problem. We develop an optimal

algorithm based on standard graph theory and Lagrangian relaxation. Based on the special structure of the problem, the

proposed resource allocation algorithm attains the optimal solution at a much lower complexity compared to general-

purpose optimization algorithms used by previous OFDMA resource allocation approaches. Moreover, the resource

allocation problem solved by the proposed algorithm supports practical features such as discrete modulation set and

multiple OFDM symbols per resource allocation decision. Furthermore, by assuming even power allocation across the

OFDM subchannels, a suboptimal resource allocation algorithm with lower complexity is developed. The proposed

algorithms enable the system designer to control the tradeoffs among system performance, system complexity, and the

quality of service (QoS) experienced by the users. Extensive simulations are conducted to evaluate the performance and

complexity of the proposed algorithms under different system operating conditions..

49 Optimal Stochastic Location Updates in Mobile Ad Hoc Networks

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We consider the location service in a mobile ad-hoc network (MANET), where each node needs to maintain its

location information by 1) frequently updating its location information within its neighboring region, which is called

neighborhood update (NU), and 2) occasionally updating its location information to certain distributed location server

in the network, which is called location server update (LSU). The trade off between the operation costs in location

updates and the performance losses of the target application due to location inaccuracies (i.e., application costs)

imposes a crucial question for nodes to decide the optimal strategy to update their location information, where the

optimality is in the sense of minimizing the overall costs. In this paper, we develop a stochastic sequential decision

framework to analyze this problem. Under a Markovian mobility model, the location update decision problem is

modeled as a Markov Decision Process (MDP). We first investigate the monotonicity properties of optimal NU and

LSU operations with respect to location inaccuracies under a general cost setting. Then, given a separable cost

structure, we show that the location update decisions of NU and LSU can be independently carried out without loss

of optimality, i.e., a separation property. From the discovered separation property of the problem structure and the

monotonicity properties of optimal actions, we find that 1) there always exists a simple optimal threshold-based

update rule for LSU operations; 2) for NU operations, an optimal threshold-based update rule exists in a low-mobility

scenario. In the case that no a priori knowledge of the MDP model is available, we also introduce a practical model-

free learning approach to find a near-optimal solution for the problem.

50 Performance of Cognitive Radio-Based Wireless Mesh Networks

Cognitive radio presents a new approach to wireless spectrum utilization and management. In this work, the potential

performance improvement gained by applying cognitive radio to wireless mesh networks is investigated. Specifically, the

potential benefits in terms of QoS provided to users and the efficiency of resource utilization are quantified in a system

consisting of a collection of one or more service provider wireless networks. To achieve this, we formulate the problem

mathematically using integer linear programming. It is shown that the cognitive radio abilities provide an advantage over

the classical network, either by improving QoS through increasing the probability of accepting connection requests, or by

reducing the resources needed to fulfill the QoS requirements of users. This advantage is gained without impacting the

service of primary clients. More importantly, we show that virtual wireless networks can be created, utilizing only the

residual wasted bandwidth of the primary service providers. These virtual networks are able to support large volumes of

users, while still ensuring that QoS reliability requirements, such as acceptance probability guarantees, are achieved.

51 Processing Continuous Range Queries with Spatiotemporal Tolerance

Continuous queries are often employed to monitor the locations of mobile objects (MOs), which are determined by

sensing devices like GPS receivers. In this paper, we tackle two challenges in processing continuous range queries

(CRQs): coping with data uncertainty inherently associated with location data, and reducing the energy consumption

of battery-powered MOs. We propose the concept of spatiotemporal tolerance for CRQ to relax a query’s accuracy

requirements in terms of a maximal acceptable error. Unlike previous works, our definition considers tolerance in

both the spatial and temporal dimensions, which offers applications more flexibility in specifying their individual

accuracy requirements. As we will show, these tolerance bounds can provide well-defined query semantics in spite

of different sources of data uncertainty. In addition, we present efficient algorithms that carefully control when an MO

should sense or report a location, while satisfying these tolerances. Thereby, we particularly reduce the number of

position sensing operations substantially, which constitute a considerable source of energy consumption. Extensive

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simulations confirm that the proposed algorithms result in large energy savings compared to nontolerant query

processing.

52 QoS-Aware Routing and Admission Control in Shadow-Fading Environments for Multirate MANETs

Providing quality of service (QoS) assurances in a mobile ad hoc network (MANET) is difficult due to node mobility,

contention for channel access, a lack of centralized co-ordination, and the unreliable nature of the wireless channel. A QoS-

aware routing (QAR) protocol and an admission control (AC) protocol are two of the most important components of a

system attempting to provide QoS guarantees in the face of the above mentioned difficulties faced. Many QAR and AC-

based solutions have been proposed, but such network layer solutions are often designed and studied with idealized lower

layer models in mind. This means that existing solutions are not designed for dealing with practical phenomena such as

shadow fading and the link quality-dependent fluctuation of link transmission rates. This paper proposes and evaluates

new solutions for improving the performance of QAR and AC protocols in the face of mobility, shadowing, and varying link

SINR. It is found that proactively maintaining backup routes for active sessions, adapting transmission rates, and routing

around temporarily low-SINR links can noticeably improve the reliability of assured throughput services.

53 Rendezvous for Cognitive Radios

Cognitive radios have been touted as a solution to communicating in a Dynamic Spectrum Access environment. This

paper examines how cognitive radios initially find one another among the expanse of ever-changing open spectrum,

termed the rendezvous problem. Specifically, it addresses the problem of rendezvous under varying levels of system

capabilities, spectrum policies, and environmental conditions. The focus is on rendezvous when there are are no

control channels or centralized controllers, which we term the blind rendezvous problem. Under these conditions, a

sequence-based and modular clock blind rendezvous algorithms are proposed, and it is shown that the performance

of these algorithms compares favorably to that of a random blind rendezvous algorithm. Specifically, the sequence-

based algorithm provides a bounded Time To Rendezvous (TTR) and the ability to prioritize channels where

rendezvous is more likely to occur; the modular clock algorithm reduces the expected TTR, requires little

precoordination among radios attempting to rendezvous, and is robust to radios sensing different sets of available

channels.

54 Scalable Localization with Mobility Prediction for Underwater Sensor Networks

Due to harsh aqueous environments, non-negligible node mobility and large network scale, localization for large-scale

mobile underwater sensor networks is very challenging. In this paper, by utilizing the predictable mobility patterns of

underwater objects, we propose a scheme, called Scalable Localization scheme with Mobility Prediction (SLMP), for

underwater sensor networks. In SLMP, localization is performed in a hierarchical way, and the whole localization process is

divided into two parts: anchor node localization and ordinary node localization. During the localization process, every node

predicts its future mobility pattern according to its past known location information, and it can estimate its future location

based on the predicted mobility pattern. Anchor nodes with known locations in the network will control the localization

process in order to balance the trade-off between localization accuracy, localization coverage, and communication cost. We

20



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conduct extensive simulations, and our results show that SLMP can greatly reduce localization communication cost while

maintaining relatively high localization coverage and localization accuracy.

55 Scalable Network Synchronization with Pulse-Coupled Oscillators

The Pulse-Coupled Oscillator (PCO) is a novel protocol inspired by models used in mathematical biology to justify

the emergence of synchrony in the natural world. Our paper introduces and demonstrates the efficacy of a new PCO

protocol implementation that, by disabling all collision resolution mechanisms for a suitable portion of the node

operations, lets the rapid establishment of a common clock and its maintenance. The key idea is to allow signals to

be superimposed in time, a feature that is absent in previous implementations, because it is prevented by traditional

medium access schemes. We map the PCO protocol into an event-driven asynchronous coloring algorithm, based on

the local exchange of information to explain its convergence properties. The event-based description of the PCO

protocol sets the stage for our experimental comparison with a competing decentralized network synchronization

approach, namely, the Reference Broadcast Protocol (RBS). For comparison, we combined RBS with an

asynchronous average consensus protocol, running exactly on the same MicaZ platforms. The experimental results

showcase the better scalability of the PCO scheme compared to the competing method based on RBS, proving that

the PCO primitive is a reasonable option to consider for wireless sensor network applications.

56 Secret Key Establishment Using Temporally and Spatially Correlated Wireless Channel Coefficients

When implementing data encryption and decryption in a symmetric cryptosystem, secure distribution of the secret key to

legitimate nodes can be a challenge. In this paper, we consider establishing secret keys using the common wireless

channel, with particular emphasis on the spatial and temporal correlations of the channel coefficients. Specifically, we

investigate the influence of channel correlation on the bound of the key size generated from the common channel using a

simple single-input single-output channel model, and we verify the existence of a sampling approach able to generate a key

using the minimum possible sampling window. We also explore decorrelation of the channel coefficients in a multiple-input

multiple-output channel, and we use a statistical independence test to demonstrate that this process cannot be separated

into spatial and temporal decorrelation processes. The insights gained from these studies assist in the development of a

practical key generation protocol based on a published channel coefficient quantization method and incorporating flexible

quantization levels, transmission of the correlation eigenvector matrix, and LDPC coding to improve key agreement in an

authenticated public channel. Finally, we present simulations with real channel measurements that solidify the fundamental

conclusions.

57 Secure High-Throughput Multicast Routing in Wireless Mesh Networks

Recent work in multicast routing for wireless mesh networks has focused on metrics that estimate link quality to

maximize throughput. Nodes must collaborate in order to compute the path metric and forward data. The assumption

that all nodes are honest and behave correctly during metric computation, propagation, and aggregation, as well as

during data forwarding, leads to unexpected consequences in adversarial networks where compromised nodes act

maliciously. In this work, we identify novel attacks against highthroughput multicast protocols in wireless mesh

networks. The attacks exploit the local estimation and global aggregation of the metric to allow attackers to attract a

21



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


large amount of traffic. We show that these attacks are very effective against multicast protocols based on high-

throughput metrics. We conclude that aggressive path selection is a double-edged sword: While it maximizes

throughput, it also increases attack effectiveness in the absence of defense mechanisms. Our approach to defend

against the identified attacks combines measurement-based detection and accusation-based reaction techniques.

The solution accommodates transient network variations and is resilient against attempts to exploit the defense

mechanism itself. A detailed security analysis of our defense scheme establishes bounds on the impact of attacks.

We demonstrate both the attacks and our defense using ODMRP, a representative multicast protocol for wireless

mesh networks, and SPP, an adaptation of the well-known ETX unicast metric to the multicast setting.

58 Secure High-Throughput Multicast Routing in Wireless Mesh Networks

Recent work in multicast routing for wireless mesh networks has focused on metrics that estimate link quality to maximize

throughput. Nodes must collaborate in order to compute the path metric and forward data. The assumption that all nodes

are honest and behave correctly during metric computation, propagation, and aggregation, as well as during data

forwarding, leads to unexpected consequences in adversarial networks where compromised nodes act maliciously. In this

work, we identify novel attacks against highthroughput multicast protocols in wireless mesh networks. The attacks exploit

the local estimation and global aggregation of the metric to allow attackers to attract a large amount of traffic. We show that

these attacks are very effective against multicast protocols based on high-throughput metrics. We conclude that aggressive

path selection is a double-edged sword: While it maximizes throughput, it also increases attack effectiveness in the

absence of defense mechanisms. Our approach to defend against the identified attacks combines measurement-based

detection and accusation-based reaction techniques. The solution accommodates transient network variations and is

resilient against attempts to exploit the defense mechanism itself. A detailed security analysis of our defense scheme

establishes bounds on the impact of attacks. We demonstrate both the attacks and our defense using ODMRP, a

representative multicast protocol for wireless mesh networks, and SPP, an adaptation of the well-known ETX unicast metric

to the multicast setting.

59 Secure Network Mobility (SeNEMO) for Real-Time Applications

The IETF NEtwork MObility (NEMO) working group has considered how to enable an entire network to move from one

location to another. Mobile Virtual Private Network (VPN) has been developed to secure mobile user’s

communication between untrusted external networks and the protected private internal network. However, the IETF’s

mobile VPN does not address how to support NEMO. In addition, it is not suitable for real-time applications. In this

paper, we propose architecture and protocols to support VPN in NEMO, which is called Secure NEMO (SeNEMO). The

proposed SeNEMO, based on Session Initiation Protocol (SIP), is specifically designed for real-time applications over

VPN. It allows an entire network to move and still maintains session continuity. In addition to analyzing the security

vulnerabilities, we also propose analytical models to evaluate the performance of the proposed SeNEMO. The

analysis is validated by extensive simulations. The results show that the proposed SeNEMO can reduce signaling

cost significantly.

60 Security Games for Vehicular Networks

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Vehicular networks (VANETs) can be used to improve transportation security, reliability, and management. This paper

investigates security aspects of VANETs within a game-theoretic framework where defensive measures are optimized with

respect to threats posed by malicious attackers. The formulations are chosen to be abstract on purpose in order to

maximize applicability of the models and solutions to future systems. The security games proposed for vehicular networks

take as an input centrality measures computed by mapping the centrality values of the car networks to the underlying road

topology. The resulting strategies help locating most valuable or vulnerable points (e.g., against jamming) in vehicular

networks. Thus, optimal deployment of traffic control and security infrastructure is investigated both in the static (e.g., fixed

roadside units) and dynamic cases (e.g., mobile law enforcement units). Multiple types of security games are studied under

varying information availability assumptions for the players, leading to fuzzy game and fictitious play formulations in

addition to classical zero-sum games. The effectiveness of the security game solutions is evaluated numerically using

realistic simulation data obtained from traffic engineering systems.

61 See-Through Walls: Motion Tracking Using Variance-Based Radio Tomography Networks

This paper presents a new method for imaging, localizing, and tracking motion behind walls in real time. The method

takes advantage of the motion-induced variance of received signal strength measurements made in a wireless peer-

to-peer network. Using a multipath channel model, we show that the signal strength on a wireless link is largely

dependent on the power contained in multipath components that travel through space containing moving objects. A

statistical model relating variance to spatial locations of movement is presented and used as a framework for the

estimation of a motion image. From the motion image, the Kalman filter is applied to recursively track the

coordinates of a moving target. Experimental results for a 34-node through-wall imaging and tracking system over a

780 square foot area are presented.

62 Spatial-Temporal Coverage Optimization in Wireless Sensor Networks

Mission-driven sensor networks usually have special lifetime requirements. However, the density of the sensors may not be

large enough to satisfy the coverage requirement while meeting the lifetime constraint at the same time. Sometimes,

coverage has to be traded for network lifetime. In this paper, we study how to schedule sensors to maximize their coverage

during a specified network lifetime. Unlike sensor deployment, where the goal is to maximize the spatial coverage, our

objective is to maximize the spatialtemporal coverage by scheduling sensors’ activity after they have been deployed. Since

the optimization problem is NP-hard, we first present a centralized heuristic whose approximation factor is proved to be 1 2

, and then, propose a distributed parallel optimization protocol (POP). In POP, nodes optimize their schedules on their own

but converge to local optimality without conflict with one another. Theoretical and simulation results show that POP

substantially outperforms other schemes in terms of network lifetime, coverage redundancy, convergence time, and event

detection probability.

63 Stealthy Attacks in Wireless Ad Hoc Networks: Detection and Countermeasure

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Stealthy packet dropping is a suite of four attacks—misrouting, power control, identity delegation, and colluding

collision—that can be easily launched against multihop wireless ad hoc networks. Stealthy packet dropping disrupts

the packet from reaching the destination through malicious behavior at an intermediate node. However, the malicious

node gives the impression to its neighbors that it performs the legitimate forwarding action. Moreover, a legitimate

node comes under suspicion. A popular method for detecting attacks in wireless networks is behavior-based

detection performed by normal network nodes through overhearing the communication in their neighborhood. This

leverages the open broadcast nature of wireless communication. An instantiation of this technology is local

monitoring. We show that local monitoring, and the wider class of overhearing-based detection, cannot detect

stealthy packet dropping attacks. Additionally, it mistakenly detects and isolates a legitimate node. We present a

protocol called SADEC that can detect and isolate stealthy packet dropping attack efficiently. SADEC presents two

techniques that can be overlaid on baseline local monitoring: having the neighbors maintain additional information

about the routing path, and adding some checking responsibility to each neighbor. Additionally, SADEC provides an

innovative mechanism to better utilize local monitoring by considerably increasing the number of nodes in a

neighborhood that can do monitoring. We show through analysis and simulation experiments that baseline local

monitoring fails to efficiently mitigate most of the presented attacks while SADEC successfully mitigates them.

64 Supporting Efficient and Scalable Multicasting over Mobile Ad Hoc Networks

Group communications are important in Mobile Ad hoc Networks (MANETs). Multicast is an efficient method for

implementing group communications. However, it is challenging to implement efficient and scalable multicast in MANET

due to the difficulty in group membership management and multicast packet forwarding over a dynamic topology. We

propose a novel Efficient Geographic Multicast Protocol (EGMP). EGMP uses a virtual-zone-based structure to implement

scalable and efficient group membership management. A networkwide zone-based bidirectional tree is constructed to

achieve more efficient membership management and multicast delivery. The position information is used to guide the zone

structure building, multicast tree construction, and multicast packet forwarding, which efficiently reduces the overhead for

route searching and tree structure maintenance. Several strategies have been proposed to further improve the efficiency of

the protocol, for example, introducing the concept of zone depth for building an optimal tree structure and integrating the

location search of group members with the hierarchical group membership management. Finally, we design a scheme to

handle empty zone problem faced by most routing protocols using a zone structure. The scalability and the efficiency of

EGMP are evaluated through simulations and quantitative analysis. Our simulation results demonstrate that EGMP has high

packet delivery ratio, and low control overhead and multicast group joining delay under all test scenarios, and is scalable to

both group size and network size. Compared to Scalable Position-Based Multicast (SPBM) [20], EGMP has significantly

lower control overhead, data transmission overhead, and multicast group joining delay.

65 Temporal Link Signature Measurements for Location Distinction

We investigate location distinction, the ability of a receiver to determine when a transmitter has changed location,

which has application for energy conservation in wireless sensor networks, for physical security of radio-tagged

objects, and for wireless network security in detection of replication attacks. In this paper, we investigate using a

measured temporal link signature to uniquely identify the link between a transmitter (TX) and a receiver (RX). When

24



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


3rd

Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


the TX changes location, or if an attacker at a different location assumes the identity of the TX, the proposed location

distinction algorithm reliably detects the change in the physical channel. This detection can be performed at a single

RX or collaboratively by multiple receivers. We use 9,000 link signatures recorded at different locations and over time

to demonstrate that our method significantly increases the detection rate and reduces the false alarm rate, in

comparison to existing methods. We present a procedure to estimate the mutual information in link and link

signature using the Edgeworth approximation. For the measured data set, we show that approximately 66 bits of link

information is contained in each measured link signature.

66 The HIDENETS Holistic Approach for the Analysis of Large Critical Mobile Systems

Dealing with large, critical mobile systems and infrastructures where ongoing changes and resilience are paramount leads

to very complex and difficult challenges for system evaluation. These challenges call for approaches that are able to

integrate several evaluation methods for the quantitative assessment of QoS indicators which have been applied so far only

to a limited extent. In this paper, we propose the holistic evaluation framework developed during the recently concluded

FP6-HIDENETS project. It is based on abstraction and decomposition, and it exploits the interactions among different

evaluation techniques including analytical, simulative, and experimental measurement approaches, to manage system

complexity. The feasibility of the holistic approach for the analysis of a complete end-to-end scenario is first illustrated

presenting two examples where mobility simulation is used in combination with stochastic analytical modeling, and then

through the development and implementation of an evaluation workflow integrating several tools and model transformation

steps.

25



Madurai




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Trichy


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Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


67 Throughput Optimization in Mobile Backbone Networks

This paper describes new algorithms for throughput optimization in a mobile backbone network. This hierarchical

communication framework combines mobile backbone nodes, which have superior mobility and communication

capability, with regular nodes, which are constrained in mobility and communication capability. An important

quantity of interest in mobile backbone networks is the number of regular nodes that can be successfully assigned

to mobile backbone nodes at a given throughput level. This paper develops a novel technique for maximizing this

quantity in networks of fixed regular nodes using mixed-integer linear programming (MILP). The MILP-based

algorithm provides a significant reduction in computation time compared to existing methods and is computationally

tractable for problems of moderate size. An approximation algorithm is also developed that is appropriate for

largescale problems. This paper presents a theoretical performance guarantee for the approximation algorithm and

also demonstrates its empirical performance. Finally, the mobile backbone network problem is extended to include

mobile regular nodes, and exact and approximate solution algorithms are presented for this extension.

68 Throughput-Lifetime Trade-Offs in Multihop Wireless Networks under an SINR-Based Interference Model

High throughput and lifetime are both crucial design objectives for a number of multihop wireless network applications. As

these two objectives are often in conflict with each other, it naturally becomes important to identify the trade-offs between

them. Several works in the literature have focused on improving one or the other, but investigating the trade-off between

throughput and lifetime has received relatively less attention. We study this trade-off between the network throughput and

lifetime for the case of fixed wireless networks, where link transmissions are coordinated to be conflict-free. We employ a

realistic interference model based on the Signal-to-Interference-and-Noise Ratio (SINR), which is usually considered

statistically sufficient to infer success or failure of wireless transmissions. Our analytical and numerical results provide

several insights into the interplay between throughput, lifetime, and transmit power. Specifically, we find that with a fixed

throughput requirement, lifetime is not monotonic with power—neither very low power nor very high power result in the

best lifetime. We also find that, for a fixed transmit power, relaxing the throughput requirement may result in a more than

proportional improvement in the lifetime for small enough relaxation factors. Taken together, our insights call for a careful

balancing of objectives when designing a wireless network for high throughput and lifetime.

69 Towards Zero Retransmission Overhead: A Symbol Level Network Coding Approach to Retransmission

We present SYNC, a physical layer transmission scheme that drastically reduces the cost of retransmission by

introducing network coding concepts to symbol level operation. It piggybacks a new packet on each retransmitted

packet, and exploits the previously received packet (possibly with error) at the receiver to recover both the

retransmitted packet and the piggybacked packet. The piggybacking is achieved through higher modulation, but it

does not decrease the decodability of the mixed packets owing to the previously received packet at the receiver,

which can be analytically shown. SYNC works independently of other PHY level performance boosting schemes such

26



Madurai




Contact : 91452 4390702, 4392702, 4394702.


Trichy


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Floor,SI Towers,



Contact : 91431 - 4002234.


Kollam




Contact : 91474 2723622.


as channel coding and spatial diversity. The proof-of-concept SYNC prototype has been implemented on a software

defined radio (SDR) platform. The measurement data shows that under the same channel condition SYNC achieves

110 percent and 42 percent median throughput gain over traditional retransmission and SOFT, respectively. We also

show that SYNC can be used proactively where the feedback as to the success of the previous transmission is not

available, such as in broadcast.

70 Traffic-Differentiation-Based Modular QoS Localized Routing for Wireless Sensor Networks

A new localized quality of service (QoS) routing protocol for wireless sensor networks (WSN) is proposed in this paper. The

proposed protocol targets WSN’s applications having different types of data traffic. It is based on differentiating QoS

requirements according to the data type, which enables to provide several and customized QoS metrics for each traffic

category. With each packet, the protocol attempts to fulfill the required data-related QoS metric(s) while considering power

efficiency. It is modular and uses geographical information, which eliminates the need of propagating routing information.

For link quality estimation, the protocol employs distributed, memory and computation efficient mechanisms. It uses a

multisink single-path approach to increase reliability. To our knowledge, this protocol is the first that makes use of the

diversity in data traffic while considering latency, reliability, residual energy in sensor nodes, and transmission power

between nodes to cast QoS metrics as a multiobjective problem. The proposed protocol can operate with any medium

access control (MAC) protocol, provided that it employs an acknowledgment (ACK) mechanism. Extensive simulation study

with scenarios of 900 nodes shows the proposed protocol outperforms all comparable state-of-the-art QoS and localized

routing protocols. Moreover, the protocol has been implemented on sensor motes and tested in a sensor network testbed.

71 Type-Aware Error Control for Robust Interactive Video Services over Time-Varying Wireless Channels

We propose a scheme called Type-Aware Error Control (TAEC) to provide robust interactive video services over

timevarying wireless channels. Basically, TAEC explores the temporal dependence of video frames by pushing out

the lower impact frames. In doing so, queuing delay is controlled and the important frame is retransmitted multiple

times. We consider the application of the nonstationary stochastic control to further improve the wireless system

throughput by exploring the multiuser diversity gain. The techniques involved in our proposed solution consist of

constructing a Markov model, reducing the number of parameters estimated, and avoiding the state explosion

problem. The provisioning of immediate bandwidth guarantee is another feature of TAEC, i.e., when exploring the

multiuser diversity gain, the users share their reserved bandwidth only if the perceived video qualities are

acceptable. As shown in the simulation, TAEC improves the perceived video quality in terms of luminance PSNR

when compared to other schemes

27

Education

IEEE Final Year Projects 2011-2012 :: Elysium Technologies Pvt Ltd::Mobilecomputingnew