[Show abstract][Hide abstract] ABSTRACT: We propose a novel MAC layer multicast scheme for the IEEE 802.11s based multi-hop WLAN mesh networks, where a layer 2 unicast routing protocol (named HWMP - Hybrid Wireless Mesh Protocol) is defined. We were motivated by the fact that no multicasting algorithm has been defined in the draft of 802.11s standard. In this paper, we present the two multicasting schemes: Layer2Multicast-Simple (L2M-S) and Layer2Multicast-Enhanced (L2M-E). In the L2M-S scheme, we simply utilize tree-based routing information created and maintained by the HWMP for the purpose of multicasting so no additional path maintenance overhead needs to be generated. Second, in the L2M-E scheme, a distributed tree optimization process is additionally introduced to further improve the performance of the MAC layer multi-hop multicasting. Simulation results using the QualNet simulator show that our protocols can reduce the data transmission overhead and improve the network throughput.
[Show abstract][Hide abstract] ABSTRACT: The IEEE 802.11s standard (Draft 3.02) defines a path selection algorithm, named HWMP (Hybrid Wireless Mesh Protocol) which combines an on-demand path selection mode with a proactive tree building mode. The proactive tree building mode in HWMP periodically maintains the routing table. Short tree update intervals can improve the accuracy of the routing table, but may cause high overhead due to frequent message transmissions. On the other hand, long update intervals may cause long delays for path recovery in case of link breaks. In this paper, we propose an efficient proactive tree building scheme that adjusts the period of messages transmitted by root mesh node for reducing the overhead. Also, it does not rebuild the whole tree but just modifies the parts of the proactive tree by the Alternative Parent Node, Local Repair and RANN solicitation to solve the problem of the broken link.