Extending WLAN coverage using infrastructureless access points

In wireless LAN (WLAN), the access point (AP) is connected to the Internet to provide network service to mobile users. Such system has limited coverage. To overcome it, a number of APs may form a wireless mesh and packets are forwarded from one AP to another by means of ad hoc connections. In this way, WLAN coverage can be cost-effectively extended to infrastructureless areas of low population and accessibility so long as one AP (namely, I-AP) is attached to the wired infrastructure. Since each AP can use multiple channels, we investigate in this paper the issue of routing and channel assignment in such an AP mesh network. We propose a routing scheme which takes the traffic load into consideration and routes the traffic through a load balanced shortest path tree (LB-SPT) rooted at the I-AP. We also propose a load-based channel assignment (LCA) scheme to judiciously assign the channels among the links. Our schemes are shown to significantly improve the system throughput and flow fairness, as compared with generic shortest path routing and uncoordinated random channel assignment.