Performance evaluation of a distributed wireless local area network employing CSMA protocol and spread spectrum signaling

We present the performance evaluation of a distributed wireless local area network, which employs multiple radio bridges for communications between each wireless terminal and a backbone LAN. The CSMA protocol with direct sequence spread spectrum signaling is employed over the wireless channel. Two system models are considered: (A) contentions occur only in the uplink and perfect receptions in the downlink, and (B) contentions happen in uplink and downlink transmissions which share a common channel. A dual persistency CSMA protocol is proposed to mitigate the unbalanced throughput of the uplink and downlink traffic in the second model. The effects of the number of radio bridges and the carrier sensing threshold on system performance are studied. Simulation results illustrate the unique property of distributed wireless local area networks in enabling multiple packet receptions, which counteracts the effects of increased interference when the number of hidden terminals is increased.