Routing in Heterogeneous Wireless Ad Hoc Networks

Existing routing protocols for wireless ad hoc networks assume a homogeneous network with either omnidirectional antennas or smart (beamforming) antennas. However it is possible to have a heterogeneous network with each node either using an omnidirectional antenna or a smart antenna. We investigate the routing and MAC layer issues that arise in such heterogeneous networks. We extend the expected number of transmissions (ETX) metric and propose a new power-controlled routing metric applicable for heterogeneous networks. This routing metric also serves the purpose of neighbor discovery, which now additionally involves finding the type of neighbor. We use information from the routing layer to propose changes at the MAC layer. We evaluate the performance of this new routing metric through simulations. We And that using smart antennas along with omnidirectional antennas improve the aggregate the network throughput up to 200 % in a random topology and up to 47 % in a grid topology. We identify issues that need further consideration for improving the performance of heterogeneous networks.