A cross-layer optimization for delay-aware load balancing in multi-radio wireless mesh networks

In this paper, we propose a cross-layer optimization technique for multi-radio Wireless Mesh Networks (WMNs) using new routing metric and load balancing mechanism. WMNs are an emerging technology and are used as a backhaul network to connect various types of networks to the internet. These networks consist of mesh routers with multi-radio support to enhance the capacity. As the traffic density is very high from the client mesh to the gateways, load balancing in these networks has become an important research issue. For this, multipath routing which can exploit the multi-radio capabilities to balance the traffic simultaneously through mesh routers is required. To address this, we analytically derive the routing metric using IEEE 802.11 Distributed Coordination Function (DCF) delay model. Using this model, we propose a routing metric called Passive Interference and Delay Aware (PIDA) metric for multipath routing to find the interference free paths. We extend the work by performing load balancing on multiple paths as well as on multiple interfaces using the proposed metric. We implement our techniques using popular Ad hoc On-demand Multipath Distance Vector (AOMDV) routing protocol in NS2. The results reveal that PIDA performs better in terms of throughput and average delay compared to recently proposed routing metrics with minimal routing overhead. In addition, load balancing mechanism with PIDA metric shows better results depending on the congestion level in the network.