Channel control for multi-radio multi-channel wireless mesh networks

Abstract

IEEE 802.11 wireless local area networks (WLANs) technologies are being considered as potential turnkey solutions for constructing infrastructures of wireless mesh networks (WMNs). With known experiments and simulation results, performances at the transport layer, including the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), have not been doing satisfactorily for connections passing through multiple hops using 802.11 technologies. Data throughput usually drops significantly when a connection has to go through more than three wireless hops. Since UDP is a simple connectionless protocol, its performance failure indicates that the design of 802.11 Medium Access Control (MAC) protocol may not be competent to handle traffic on the wireless mesh networks. In this paper, a multi-radio multi-channel wireless mesh network architecture with a novel MAC protocol design is proposed. The MAC protocol extends the Request-to-Send/Clear-to-Send message pair in 802.11 for channel reservation operations. Only two stations at an instant can have the sole possession of a specific channel with an announced duration. During this duration, the two stations can establish a connection for sending multiple segments to each other, if needed. This per-hop reservation concept can further be deployed into multi-hop wireless networks, and high throughput data rate should be achievable for multi-hop TCP and UDP connections.