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.

中文翻译：

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无线网络上基于OFDMA的自适应CSMA / CA方案的性能分析

常规的载波侦听多路访问/冲突避免（CSMA / CA）IEEE 802.11协议使用分配协调功能（DCF）的刚性二进制指数退避算法进行信道访问。该协议在丢包率高的无线链接和密集网络中（隐藏节点产生大量冲突）在丢失情况下的性能较差。此外，该方案在其操作中不认识无线链路的状态。这项工作开发了混合自适应正交频分多址（OFDMA）CSMA / CA（混合AO–CSMA / CA）协议，该协议根据无线信道状况的知识来调整退避和拥塞窗口大小，以减轻损失的影响通过无线链接。该协议利用OFDM进行有效的资源分配，并解决了基于OFDMA IEEE 802.11的无线网络上隐藏终端节点的问题。在实际的动态马尔可夫无线信道上，根据吞吐量和延迟指标研究了开发协议的电信性能分析。性能结果表明，所开发的混合协议在有损无线通信链路上的性能优于DCF协议。