High Data Rate Wireless Networks: A Power Efficiency Perspective

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High Data Rate Wireless Networks: A Power Efficiency PerspectiveB. Aazhang and A. SabharwalDepartment of Electrical and Computer Engineering, Rice UniversityIn 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. To meet the challenges of next generation wireless systems, there is a need for fundamentally new understanding in cross-layer design as well as new methods which exploit all available dimensions for optimizations. The following agenda outlines the key elements of the research framework we are pursuing to achieve increased power efficiency while simultaneously increasing system wide throughput.1. Fairness, delay and power efficiency: Traditionally network protocols address throughput fairnessamong users and delay requirement of applications while communication algorithms address location dependent reliability, transceiver power, and channel access. This project develops a framework to systematically analyze and design power efficient access and scheduling protocols. Using short time scale channel variations along with source burstiness, the minimal power opportunistic scheduler will meet delay requirements while maintaining a system wide statistical fairness.2. Scalable space-time codes: To achieve the gains from packet and flow scheduling, it is critical that the physical layer coding be able to serve the scheduled data rates. At the same time to achieve high levels of spectral and power efficiency, it is important that the coding methods exploit as much information available regarding the channel at the transmitter. Thus, the design space targeted by this research project covers a wide range of mobile speeds and channel conditions. In particular, space-time codes are designed that have either imprecise or no channel information at the receiver with no information at the transmitter, covering high to medium mobile speed communications. And for low speed mobiles, the project addresses the fundamental issues in the design of efficient feedback channels for space-time coding methods.3. Integration into wireless research platform: The strong theoretical innovations for low powerdesign are tested on the rapid prototyping platform for multiple antenna systems at Rice University. The end-to-end system design and development is stress tested, and the power and spectral efficiency of the overall system is quantified.The ongoing research paves the way to understand the fundamental relationships among spectral efficiency, algorithm complexity, and power consumption to increase the utility of wireless capable mobile devices and to directly impact their emerging market. The broader impact of the project on education is ensured by engaging a large number of undergraduate and graduate students in projects in our laboratory.