My expertise and general interests span the areas of communications, networking and statistical signal processing -- subjects on which I have co-authored more than 250 journal papers, 450 conference papers and four books.

Current research focuses on cooperative (relay) communications, cognitive radios, cross-layer designs, mobile ad hoc networks and wireless sensor networks.

Past research topics in wireless communications have included transmitter and receiver diversity techniques for single-user and multi-user fading channels, compensation of nonlinear amplifier effects, linear precoding, space-time coding for multi-antenna systems, synchronization, multicarrier, and ultra-wideband wireless communication systems. Additional research themes in statistical signal processing dealt with time series analysis, system identificaton, (poly) spectral analysis, wavelets, cyclostationary, and non-Gaussian signal processing with applications to array and image processing.