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Tuning the Carrier Sensing Range of IEEE 802.11 MAC
Jing Deng,Ben Liang and Pramod K. Varshney
Univ. of New OrleansGlobecom 2004
Outline
Problem of Fixed Carrier Sensing Range
Carrier Sensing Range Optimization PERFORMANCE EVALUATION CONCLUSIONS
Problem of Fixed Carrier Sensing Range The transmission range (R)
The range inside which nodes are able to receive or overhear the packet transmission
The carrier sensing range (Rs) The range inside which nodes are able to
sense the signal, even though correct packet reception may not be available
Problem of Fixed Carrier Sensing Range The interference range (Ri)
The range inside which any new transmission may interfere with the packet reception
Problem of Fixed Carrier Sensing Range Rs is a tunable parameter. In NS2
Rs = 2.2 R
Problem of Fixed Carrier Sensing Range
Problem of Fixed Carrier Sensing Range
Problem of Fixed Carrier Sensing Range
Node C is free to start any transmission when node B is receiving. Node C is not a hidden term
inal Distant Terminal Problem
Carrier Sensing Range Optimization larger Rs
packet collision rate to decrease leads to a lower level of spatial frequency
reuse
Carrier Sensing Range Optimization η = NS – cNd
NS
The channel throughput Nd
Total amount of transmitted data
PERFORMANCE EVALUATION NS2 simulator CPThreshold
10 dB The transmission range
250m The data packet length
2000 Bytes The simulation time
4 seconds
Effect of Carrier Sensing Range
2560 /( N-1 ) m
PERFORMANCE EVALUATION
PERFORMANCE EVALUATION
Carrier Sensing Range Optimization N nodes are uniformly distributed in
Y m2 network The value of Y is set to 50N.
All traffic are sent to a randomly selected immediate neighbor.
PERFORMANCE EVALUATION
PERFORMANCE EVALUATION
PERFORMANCE EVALUATION
PERFORMANCE EVALUATION
CONCLUSIONS Using this model, we can determine t
he optimal carrier sensing range of CSMA for any ad hoc network.
Our study shows that an optimally chosen carrier sensing range can Increase the network throughput Decrease the number of data packet colli
sions