Systems Seminar
An Integrated Signal Processing Framework for Multiuser Wireless Communications
Prof. Akbar Sayeed
UW ECE Department
Abstract
Code division multiple access (CDMA) has emerged as a dominant
technology for meeting the physical layer challenges of future
wireless communication systems. Signal processing requirements
in the physical layer are dictated by three major factors:
multiaccess interference, multipath dispersion and fading, and
transceiver complexity. Existing CDMA system designs reflect a
piecemeal approach due to the lack of an effective framework
for jointly addressing these issues. We propose signal
processing in canonical multipath-Doppler coordinates for
attacking physical layer impairments in an integrated fashion.
The canonical coordinates are derived from a fundamental
characterization of channel propagation dynamics in terms of
discrete multipath-delayed and Doppler-shifted copies of the
spread-spectrum signaling waveforms. The multipath-Doppler
shifted waveforms constitute an approximately orthogonal
basis and the corresponding signal representation naturally
connects the various channel effects. First, all processing
relating to multipath propagation can be directly performed
in the canonical coordinates. Second, the same coordinates
provide a canonical subspace-based representation of the
desired signal and interference which fully incorporates
channel dispersion effects. Finally, the maximally
parsimonious nature of the coordinates and their simple
computation afford a direct handle on transceiver complexity.
Various facets of the integrated framework are illustrated
in the context of interference suppression, channel
estimation, and diversity processing.
Time and Place: Wed., Oct. 28, 3:45-4:45 pm in 4610 Engr. Hall.
SYSTEMS SEMINAR WEB PAGE:
http://www.cae.wisc.edu/~gubner/seminar/