Performance analysis of an adaptive OFDMA‐based CSMA/CA scheme on a wireless network

Abstract

The conventional carrier-sense multiple access/collision avoidance (CSMA/CA) IEEE 802.11 protocol uses the rigid binary exponential backoff algorithm of the distribution coordination function (DCF) for channel access. The protocol poorly performs under loss by wireless links with high packet error rates and dense networks with numerous collisions from hidden nodes. Furthermore, the scheme is not cognisant of the state of the wireless link in its operation. This work develops hybrid adaptive orthogonal frequency division multiple access (OFDMA) CSMA/CA (hybrid AO–CSMA/CA) protocol that adapts the backoff and congestion window size according to the knowledge of the wireless channel conditions to mitigate against the effects of the loss by wireless links. The protocol utilises OFDM for effective resource allocation and solving the problem of the hidden terminal node on an OFDMA IEEE 802.11-based wireless network. The teletraffic performance analysis of the developed protocol is investigated in terms of throughput and delay metrics on a real dynamic Markovian wireless channel. The performance results indicate that the developed hybrid protocols perform better than the DCF protocol on the lossy wireless communication links.