Applications and challenges of the 802.11e EDCA mechanism: an experimental study

In this article we conduct an experimental study of the enhanced distributed channel access mechanism of the upcoming 802.11e standard. The main focus of the study is on two applications of EDCA: traffic engineering and service guarantees. With traffic engineering we aim at distributing the bandwidth in the WLAN according to a given throughput allocation criterion. With service guarantees the objective is to ensure that the performance metrics (throughput and delay) experienced by a station meet a given quality criterion. We build a testbed with wireless cards that support a substantial subset of the EDCA functionality and analyze performance against different sets of requirements. Experimental results show that EDCA can effectively be used for traffic engineering purposes. The goal of providing service guarantees with EDCA is shown to be more challenging; we identify future research directions that need to be addressed in order to achieve this goal.