WINLAB Seminar - J. Nicholas Laneman "The Role of Temporal Correlation in Communication over..."

Title: "The Role of Temporal Correlation in Communication over Fading Channels: An Exploration from Low to High SNR" Date: August 19, 2005 1:30 PM Speaker: J. Nicholas Laneman Abstract: In this talk we investigate the effects of temporal correlation on the behavior of scalar, frequency-flat Rayleigh fading channels without channel state information. The channel behavior depends upon both the degree of channel correlation and the operating signal-to-noise ratio (SNR). We review existing results for correlated channels at high SNR and memoryless channels at low SNR. Channel transformation techniques are used to simplify analysis of correlated channels at low SNR and memoryless channels at high SNR. For slow fading channels, we develop a recursive channel estimator based upon block decision feedback that converts the noncoherent channel into a coherent channel with additional noise. Using asymptotic results for low SNR, we demonstrate that phase-shift keying (PSK) can perform reasonably well for typical slow fading channels with peak-power constraints. For fast fading channels, we derive an equivalent channel model involving only additive, non-Gaussian noise. This induced additive-noise channel provides some intuition about previous results for the memoryless channel model, provides simple bounds on the mutual information, and allows for efficient signal design at high SNR.