A Dynamic Virtual Carrier Sensing and Interference Aware Routing Protocol in Wireless Mesh Networks

The performance of wireless mesh networks is severely limited by the interfering nature of wireless transmissions. In an 802.11 network, collisions can be aggravated by the hidden terminal problem. In order to solve the hidden terminal problem, virtual carrier sensing using RTS/CTS has been proposed as a solution. However, this mechanism potentially aggravates the exposed terminal problem which can neutralize or even reverse the gains in using it. Another problem is that most dynamic routing protocol select paths based on only one criteria (shortest hops, delay etc), which do not take into account of interference or traffic pattern. There has been some work in this area in which combinations of two or more criteria are considered for the routing. However, there has not been any work that jointly considers both the effects of the virtual carrier sensing together with network interference. In this paper, we proposed a dynamic virtual carrier sensing and interference aware routing protocol (DVCSIR) to select the optimum path based on two criteria, shortest path and Quietness Index. We define Quietness Index (QI) as a metric to predict the amount of interference experienced by a node. This will be used to activate the virtual carrier sensing mechanism dynamically on a node by node basis. It will also be used as a path selection metric. There are two advantages to this approach. Firstly, the path selected by DVCSIR will experience less interference, and thus suffer from less collisions and packet drops. Secondly, the dynamic virtual carrier sensing mechanism ensures that RTS/CTS packet exchanges only take place in parts of the network where it is most effective, i.e., where there are many hidden nodes and minimal exposed nodes. We conduct simulations in OPNET to compare DVCSIR with other routing protocol, e.g., Dynamic Source Routing (DSR). The results demonstrate that DVCSIR could achieve better performance.