Cross Layer Design for the IEEE 802.11 WLANs: Joint Rate Control and Packet Scheduling

With the rapid development in wireless communication technologies, the IEEE 802.11 WLANs are experiencing a huge popularity and widespread deployment. Designed with traditional layered architecture, current WLANs adopt functional layer partitioning and aim at optimization at individual layers. However, in a highly dynamic and media sharing wireless environment, the capacity enhancements at individual physical layers may not necessarily benefit, and sometimes even degrade the system performance with multiple users. It has been shown that in a multiuser setting, one can increase the throughput substantially if partial knowledge of the channels at the receiver sides is known. The challenge is to make good matching of the instantaneous channel conditions of multiple users with the bandwidth and time allocation to each user. In this paper, we address the issue of cross layer design in the proposed "weighted fair scheduling based on adaptive rate control" (WFS-ARC) framework, where the PHY layer knowledge is shared with the MAC and LLC layer in order to provide efficient resource allocation. We evaluate the WFS-ARC approach in ns-2 and the simulation results demonstrate that our design can significantly improve the system throughput.