A study of root driven routing protocol for wireless LAN mesh networks

Wireless LAN mesh networks (or Mesh WLANs) are being widely deployed as a new wireless access network that employs a key technology of multihop communications to link the edges of the mesh to a mesh portal, which connect to other wired networks. In such deployment, the Mesh WLAN backbone topology can be efficiently constructed among the mesh nodes by using a proactive routing protocol due to low or no mobility in mesh nodes. A tree-based routing (TBR) protocol is a viable proactive routing protocol for the Mesh WLAN, because it is well-suited for the user traffic that is directed to/from a wired network via the mesh portal (i.e., the root). However, the performance of TBR protocol is rapidly degraded when the user traffic is mostly dominated by the intra-mesh traffic, since the traffic within the Mesh WLANs must also bypass the root, which unnecessarily overloads the root by routes without using the best-metric route. Especially, it becomes more serious if the network size is significantly large whereby the amount of traffic inside mesh network increases dramatically. To mitigate this shortcoming, in this paper we propose a root driven routing protocol to enable the root to quickly provide the best-metric route for any source-destination pair of intra-mesh traffic. Furthermore, we combine the proposed protocol for intra-mesh traffic and the original TBR protocol for inter-mesh traffic as a hybrid routing protocol to achieve the best performance in the Mesh WLAN networks. Our simulation results reveal that the proposed protocol outperforms the TBR protocol with much lower average end-to-end delay and much higher packet delivery ratio.