Cross-Layer Enhancement for WLAN Systems with Heterogeneous Traffic Based on DQCA

Voice transmission over WLAN and cross-layer optimization are emerging research topics. This paper proposes two novel cross-layer mechanisms for a WLAN system where the offered traffic is of mixed nature (voice and data) while using a distributed MAC protocol. On one hand, the performance of the proposed mechanisms has been analyzed, and a significant system efficiency improvement in terms of throughput and packet delay for data nodes is shown. On the other hand, a remarkable increase in the number of simultaneous possible voice nodes is also achieved. These benefits are obtained 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 behavior as they present a trade-off between system enhancement and fairness in resource assignment among the nodes. The obtained results emphasize the advantages of the proposed schemes and the importance of Cross-Layer design in wireless communication systems.