Algorithms for Wireless Communication Systems: A Power-Efficiency Perspective

Within the last five years, there has been a cultural shift from wired landlocked connectivity to pervasive wireless information access. Most emerging mobile devices are now equipped with some form of embedded wireless radio. The expectations of high data rates and increased battery longevity have put tremendous pressure on all aspects of wireless system design. The goal of our projects at the Center for Multimedia Communication at Rice is to develop powerefficient wireless enabled mobile devices. In this paper, we will consider the control and coding issues to increase active access time of mobile communication devices. In particular, we develop scheduling algorithms which adaptively change the transmission power and rate, based on both the transmission queue backlog and the channel conditions. The packet level control algorithms exploit burstiness of data streams and channel variations to trade packet queuing delay with the average transmit power. The wide range of data rates dictated by the scheduler and our power efficiency objective is effectively met by a multi-antenna transceiver. We design non-coherent space-time codes for high mobile speeds, and space-time feedback strategies for low mobility applications. This paper highlights some of the proposed methods and presents some preliminary results.