Performance Evaluation of IEEE 802.11e Medium Access Control in Fiber-fed Networks

An evaluation of the performance of the IEEE 802.11e medium access control (MAC) for quality-of-service (QoS) support in 802.11 networks has been carried out in a fiber-fed wireless local area network (WLAN) scenario. The effect of the additional optical path delay on the effectiveness of the new mechanisms of the 802.11e extension for efficiency increase, i.e., the burst transmission, and new ACK policies have been investigated. It is shown by means of analysis and simulations that although the fiber delay degrades the performance of the new mechanisms, compared with the original 802.11 MAC, significant throughput improvement can be gained when burst transmission is used with the Immediate, Block, or No ACK policies in fiber-fed networks. An experimental evaluation of the throughput improvement with the 802.11e extension is also reported. Our measurements, supported by simulations, show that higher layer operation can have a significant effect on the performance of the new MAC mechanisms, especially when transmission errors are present.