  The ability to perform traffic differentiation is a promising feature of the
current Medium Access Control (MAC) in Wireless Local Area Networks (WLANs).
The Enhanced Distributed Channel Access (EDCA) protocol for WLANs proposes up
to four Access Categories (AC) that can be mapped to different traffic
priorities. High priority ACs are allowed to transmit more often than low
priority ACs, providing a way of prioritising delay sensitive traffic like
voice calls or video streaming. Further, EDCA also considers the intricacies
related to the management of multiple queues, virtual collisions and traffic
differentiation. Nevertheless, EDCA falls short in efficiency when performing
in dense WLAN scenarios. Its collision-prone contention mechanism degrades the
overall throughput to the point of starving low priority ACs, and produce
priority inversions at high number of contenders. Carrier Sense Multiple Access
with Enhanced Collision Avoidance (CSMA/ECA) is a compatible MAC protocol for
WLANs which is also capable of providing traffic differentiation. Contrary to
EDCA, CSMA/ECA uses a contention mechanism with a deterministic backoff
technique which is capable of constructing collision-free schedules for many
nodes with multiple active ACs, extending the network capacity without starving
low priority ACs, as experienced in EDCA. This work analyses traffic
differentiation with CSMA/ECA by describing the mechanisms used to construct
collision-free schedules with multiple queues. Additionally, evaluates the
performance under different traffic conditions and a growing number of
contenders. (arXiv's abstract field is not large enough for the paper's
abstract, please download the paper for the complete abstract.)
