Rate management in multiuser detection based MAC design for ad hoc networks

We propose a framework that produces synergy between Medium Access Control (MAC) and physical layers in order to increase the users’ individual throughput in a high-capacity CDMA ad hoc network. The MAC layer supports a multiuser detection based access protocol. Users send data packets at different rates, depending on the fading channel state. The framework is based on an LMS (Least Mean Square) prediction algorithm that estimates channel gain at the physical layer. The performance of the scheme is evaluated by simulations. Multiuser detection typically triples the throughput of ad hoc networks but our prediction-based scheme further doubles this metric. The main advantage of the proposed scheme is its flexibility and efficiency in a wide range of data rates and target bit error rates. It is also well fitted to support high-quality multi-media transmissions, and to improve the performance of applications that require high quality of service (QoS).