Random access schemes for multichannel communication and multipacket reception in wireless networks.

Abstract

Random access schemes have used advanced capabilities of the physical layer to achieve reliable data transmissions over wireless communication channels. These capabilities include multichannel communication and multipacket reception. Incorporating the advanced capabilities into the access schemes, as a cross-layer design, is a challenging task because a more sophisticated approach is required to interface the physical layer and the medium access control (MAC) layer. This thesis presents development of research into the efficient random access schemes that provide a better set of cross-layer design approaches by taking into account the capabilities of multichannel communication and multipacket reception. The consideration is to propose multichannel random access schemes that use a channel outage concept of fading and interference. The system performance of the proposed schemes is then analysed. By considering imperfect channel information, a random backoff access scheme that operates with a channel sensing policy is developed. The sensing and access problem is formulated as a partially observable Markov decision process, and is solved with simple and efficient heuristic approaches. A new joint random access scheme that resolves packet collisions in the time and frequency domains is then proposed to enable effective uplink access. The joint scheme cooperates with a sensing method in which users are partially aware of channel conditions. With multipacket reception (MPR) capability, a new MAC protocol is developed by adopting a distributed access mechanism to support a wireless network in which MPR capable nodes coexist with non-MPR nodes.