Cross-Layer Enhancement for WLAN Systems based on a Distributed Queuing MAC protocol

Cross-Layer optimization is an emerging research topic. This paper proposes two novel cross-layer mechanisms to be included in a WLAN system where a near-optimum distributed MAC protocol is used. Their performance in terms of throughput and packet delay is analysed, and a significant system efficiency improvement is shown. This benefit is achieved by means of a PHY-MAC dialogue and a smart scheduling of the radio resources. Transmissions are scheduled taking into account the measurements of the channel state and the waiting time of packets in the accessing system. The two proposed mechanisms have different performance behaviour and thus present a trade-off between system enhancement and fairness. The obtained results emphasize the advantages of the proposed schemes and the importance of cross-layer design in wireless communication systems