Analysis of capacity in ad hoc networks with variable data rates

We investigate how to use a variable data rate in ad hoc TDMA networks and the possible gain in throughput. The use of variable data rates enables the network to adapt to changes in the environment, which is crucial for the ability to guarantee QoS in a mobile network. We study the impact of the routing metric and traffic adaptivity on the network´s ability to utilize variable data rates. The results show that it is of paramount importance to take data rate into consideration when routing, especially when a variable data rate is used to add long-range, low data rate links. Further, traffic adaptivity plays an important role in the utilization of variable data rates at the network level. We also study how the number of data rates to choose from affects the throughput. For the studied network topologies, the benefit of having many data rates is not obvious. Furthermore, the results show a substantial improvement in throughput for a system with a variable data rate compared to a system with a fixed data rate.