2005 Reports

802.11b Throughput with Link Interference

Chang, Hoon; Misra, Vishal

IEEE 802.11 MAC is a CSMA/CA protocol and uses RTS/CTS exchanges to avoid the hidden terminal problem. Recent findings have revealed that the carriersensing range set in current major implementations does not detect and prevent all interference signals even using RTS/CTS access method together. In this paper, we investigate the effect of interference and develop a mathematical model for it. We demonstrate that the 802.11 DCF does not properly act on the interference channel due to the small size and the exponential increment of backoff windows. The accuracy of our model is verified via simulations. Based on an insight from our model, we present a simple protocol that operates on the top of 802.11 MAC layer and achieves more throughput than rate-adjustment schemes.