CAREER: Coding for Wireless Communications

Arizona State University, Scottsdale AZ

Investigators

Abstract

Abstract: --------- The demand for voice and data transmission over wireless channels is increasing at a tremendous pace. Unfortunately, the characteristics of the wireless channel (e.g., fading and interference) impose obstacles for satisfying this demand. The single most effective technique to accomplish reliable communication over a fading channel is ``diversity'' which attempts to provide the receiver with independently faded copies of the transmitted signal. Channel coding may also be used to provide (a form of time) diversity for immunization against the impairments of the wireless channel. In addition, various diversity techniques may be combined to further improve the system performance in a wireless environment. Space-time coding which combines channel coding with space diversity is a recent example of combining different diversity techniques and has proven to be effective in providing high data rates over fading channels. This research involves development of new channel coding techniques for the wireless link. In particular, coded modulation techniques for multiple transmit and multiple receive antenna systems over block fading channels are developed. A significant part of the research includes development of turbo (based) coded modulation techniques as an alternative to the current space-time codes. In addition, the investigators study the use of multilevel codes and bit interleaved coded modulation schemes for systems with antenna diversity. They conduct a theoretical performance analysis of various coded modulation systems, develop code design principles, and devise simpler and efficient decoding algorithms. In addition, they consider practical issues including the evaluation of code performance in the presence of interference.