Policy-based channel access mechanism selection for QoS provision in IEEE 802.11e

The appearance of the 802.11e standard made the 802.11 wireless local area networks (WLANs) capable of providing different levels of quality of service (QoS). This standard defines two new channel access mechanisms (CAMs), namely the enhanced distributed channel access (EDCA) and the HCF controlled channel access (HCCA). The introduction of two CAMs increases the complexity of traffic management, since now not only the available resources have to be distributed, but also the optimal CAM for each data flow has to be selected. However, the best CAM selection algorithm is still not clear. This paper presents and analyses different CAM selection policies in order to derive the best-suited strategy in terms of system performance. From this study, an optimal policy, based on traffic type and direction (uplink or downlink), is proposed. The best user QoS satisfaction shown in the results confirms the good performance of this new selection policy.