CSMA/CA with multiple-variable contention window for wireless multimedia communication systems

For variable-bit-rate multimedia traffic sources, a carrier-sense multiple-access with collision avoidance (CSMA/CA) protocol using a multiple-variable contention window is proposed. In this proposed scheme, the initial setting of the contention window is primarily based on fairness on radio channel access and characteristics of the traffic source as opposed to other existing CSMA/CA schemes that are mostly based on the traffic load of the radio link. The performance of the proposed scheme is evaluated by computer simulation in fading channels, utilizing the IEEE 802.11a physical layer based on orthogonal frequency division multiplexing (OFDM) with classification of packet lengths into several subgroups. When compared to the existing IEEE 802.11 WLAN MAC where a single variable contention window is used for all packets, the approach improves the throughput performance with short packets by about 23%.