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Introduction Benefits of Directional Antennas Spatial reuse Longer transmission and reception range Higher network capacity Less interference Fewer transmission hops
Citation preview
Cooperation and Directionality: Friends or Foes?Zhifeng Tao, Thanasis Korakis, Feilu Liu, Shivendra Panwar, Jinyun Zhang, Leandros Tassiulas
IEEE ICC 2008
Outline
Introduction Proposed Method Performance Evaluation and Comparison Conclusions
Introduction
Benefits of Directional AntennasSpatial reuseLonger transmission and reception rangeHigher network capacityLess interferenceFewer transmission hops
Introduction
Benefits of Cooperative CommunicationSpatial diversityHigher capacityReliabilityExtended coverage
Introduction
DistinctionDirectional antenna relies on directional
transmission of wireless signalCooperative communications depend on the
broadcast nature of wireless channel
Motivation and Goal
Motivation Although a handful of MAC protocols have already
been proposed to support either directional antenna or cooperative communications, nothing exist that can exploit both simultaneously
Goal Proposed a MAC that taps into the combined potential of
both transmission directionality and cooperation diversity
Network Model
Two hosts are said to be neighbors if they can communicate with each other over a wireless link.
We assume that each node knows its neighbors‘ location as well as its own location.
A B
A B
phy layer
MAC layerData Flow
Antenna Model
Proposed Methods
O-CoopMACCooperative MAC with Omni-directional antenna
D-NoopMACNon-Cooperative MAC with Directional antenna
D-CoopMACCooperative MAC with Directional antenna
O-CoopMAC(Cooperative MAC with Omni-directional antenna)
Ss
Sr
Sd
Cooperation Table of Ss
Index (MAC address) Link Rate
Ss Lsr Rsr
Ss Lsd Rsd
Sr Lrd Rrd
… … … Sd Ldr Ldr
… … …
RTSHTS
HTSCTS
CTS
1st hop data@Rsr 2nd hop data@Rrd
ACK
D-NoopMAC(Non-Cooperative MAC with Directional antenna)
RTSCTSACK
A B
Data
D-CoopMAC(Cooperative MAC with Directional antenna)
Ss
Sr
Sd
Cooperation Table of Ss
Index (MAC address) Link Rate
Ss Lsr Rsr
Ss Lsd Rsd
Sr Lrd Rrd
… … … Sd Ldr Ldr
… … …
RTS HTS
CTS
1st hop data@Rsr
2nd hop data@Rrd
ACK
Performance Simulation and Comparison
Simulation Settings
Baseline IEEE 802.11g
Deployment Random
Network size (in radius) 350m
Radius of omnidirectional antenna 100m
Directional antenna's lobe of radius 119m and 141m
beams number of directional antenna 2 and 4
Throughput versus Number of Stations
Channel access delay
Throughput versus Traffic Load(100 stations)
Throughput versus Traffic Load(300 stations)
Conclusions
This paper has presented three new MAC protocol for ad-hoc networks
To establish a deeper understanding of the relative performance of cooperative communications and directional transmission
Cooperation and directionality can be rather foes than friends
Thank you
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