Systems Seminar

The Holy Grid of Wireless Communications

Prof. Akbar Sayeed
UW ECE Dept.

Abstract

Mobile wireless connectivity is a salient feature of the emerging global information infrastructure. The major obstacles in achieving reliable, high-bandwidth connectivity stem from the harsh time-varying characteristics of the wireless channel, including signal fading, dispersion, and multiuser interference. Code division multiple access (CDMA) has emerged as a promising technology for addressing these physical layer challenges. However, a major stumbling block in effectively combating these channel impediments is accurate yet tractable modeling of propagation dynamics.

We introduce an integrated framework for CDMA physical layer design in terms of canonical channel modes (CCMs). The CCMs are defined by fixed space-time basis waveforms that correspond to a fundamental sampling of multipath delays, Doppler shifts, and spatial angles on a uniform grid. The power of the CCM framework rests on the fact that the CCMs simultaneously provide a natural decomposition of the dispersive wireless channel into nondispersive virtual channels as well as a natural set of basis waveforms for the overall signal space. The usefulness of the CCM framework is illustrated in various facets of system design, including diversity processing, interference suppression, channel estimation, bandwidth-efficient signaling and interfacing with higher network layers.

Time and Place: Wed., Dec. 1, 3:30-4:30 pm in 4610 Engr. Hall.

SYSTEMS SEMINAR WEB PAGE: http://www.cae.wisc.edu/~gubner/seminar/