面向QoS的下一代WLAN OFDMA多址接入协议
QoS-Oriented OFDMA MAC Protocol for the Next Generation WLAN

随着无线服务的日趋多样化和业务量的爆炸式增长，服务质量（quality of service，QoS）的保障是下一代无线局域网（wireless local area network，WLAN）的重要目标之一。正交频分多址（orthogonal frequency division multiple access，OFDMA）是下一代WLAN的重要特性，然而已有的关于下一代WLAN的多址接入协议研究或者较少关注QoS保障，或者对于公平性保障较差。文章提出了一种面向QoS的下一代WLAN OFDMA多址接入协议：QoS-OFDMA。该协议引入了2次OFDMA并行随机接入的思想，第1次随机接入不区分业务优先级，从而保障了公平性；进一步允许第1次随机接入失败的高优先级用户，在分配剩余的可用子信道上，进行第2次随机接入，从而保障了高优先级业务的QoS。仿真结果表明，与RA-OFDMA协议和OMAX协议相比，QoS-OFDMA高优先级业务吞吐量分别提升了22.05%和89.6%，同时很好地保障了低优先级业务公平性。
With the increasingly diverse services and the explosively growing traffic, quality of services (QoS) guarantee is one of the most important goals of next generation wireless local area network (WLAN). Orthogonal frequency division multiple access (OFDMA) is an important feature of next generation WLAN. However, many existing studies focusing on the media access control protocol of the next generation WLAN neglect the guarantee of QoS and fairness. In this paper, we propose a QoS oriented OFDMA multiple access protocol for the next generation WLAN, named QoS-OFDMA. QoS-OFDMA introduces two times random access. The first random access does not distinguish the service priority, which guarantees the fairness. Meanwhile, the high-priority users failing to first random access are allowed to perform a second random access on the remaining available sub-channel. Thus, it improves the QoS of the high priority traffic. Simulation results show that compared with RA-OFDMA protocol and OMAX protocol, QoS-OFDMA high-priority service throughput outperform both by 22.05% and 89.6% respectively, and also guarantee the fairness requirement