Broadcast in Multirate Ad Hoc Networks

Transmission time on a single radio link decreases with increasing data rate. In a broadcasting setting in an entire ad hoc radio network, this is not necessary so, since the number of retransmissions needed may grow with increasing data rate due to reduced transmission range. Often there is a non-trivial optimum rate to be found. We have studied the problem of optimizing the total time needed for broadcasting a message in an ad hoc radio network under the assumption that data rate can be traded for transmission range. We have analyzed this from a theoretical point of view and found optimal rates to use, given some model assumptions. Based on these finding we have proposed a rate choice algorithm and compared it to some other rate choice algorithms under realistic assumptions about the communication parameters. It was found that the proposed algorithm yields a good performance in most cases while at the same time being well suited for implementation in a distributed environment.