A Simulation Approach to a Robust Multi-radio Multi-channel Wireless Ad Hoc Network

In traditional wireless ad hoc mesh networks where all nodes communicate through the same medium the performance can be strongly impaired by mutual interference and contention. The network performance can be improved by using multiple orthogonal frequency channels; such a multi-channel ad hoc network can be implemented by equipping each node with multiple radio devices, e.g. 802.11 network interface cards, which can switch (at relatively low speed) between different channels. A simulation program was developed to gain insight in the behavior of wireless ad hoc networks, specially at the lower layers, and to investigate how the potential performance gain of multiple channels depends on the number of radios per node and the number of channels used. The use of different channels may introduce a connectivity issue: if nodes do not share a common channel, they have no connection. The design of a multi-channel wireless ad hoc network involves taking precautions to avoid such loss of connectivity. This connectivity issue is discussed, and a robust scheme that ensures connectivity is presented.