Enhancing enhanced distributed channel access function based on cross-layer information for multirate wireless networks

Abstract

IEEE 802.11e provides guaranteed quality of service (QoS) by proving different transmission priorities. IEEE 802.11e improves the media access control layer of IEEE 802.11 to satisfy the different QoS requirements by introducing two new channel access functions: the enhanced distributed channel access (EDCA) and the hybrid coordination function-controlled channel access. The available bandwidth and transmission rate may be easily affected by the signal quality, because the communication channel in a wireless environment operates in a random time-variation manner. Generally, a station using a low transmission rate will occupy the communication channel for a long time and degrade system performance, which causes bandwidth waste and unfairness; thus the guaranteed QoS for stations with higher transmission rates cannot be provided. An enhancing EDCAF (E2DCAF) is proposed that consolidates the cross-layer concept and the IEEE 802.11e EDCAF protocol. After simulation experiments, E2DCAF obviously improves performance, especially in throughput and fairness. E2DCAF scheduling also allows the different QoS requirements to be processed efficiently and flexibly.