Code-Multiplexing-Based One-Way Detect-and-Forward Relaying Schemes for Multiuser UWB MIMO Systems

In this paper, we consider decode-and-forward (DF) one-way relaying schemes for multiuser impulse-radio ultrawideband (UWB) communications. We assume low-complexity terminals with limited processing capabilities and a central transceiver unit (i.e., the relay) with a higher computational capacity. All nodes have a single antenna differently from the relay in which multiple antennas may be installed. In order to keep the complexity as low as possible, we concentrate on noncoherent transceiver architectures based on multiuser code-multiplexing transmitted-reference schemes. We propose various relaying systems with different computational complexity and different levels of required channel knowledge. The proposed schemes largely outperform systems without relay in terms of both bit error rate (BER) performance and coverage

GLRT-Based Combining Schemes for PPM IR-UWB Systems with Multiple Receive Antennas

This paper deals with impulse-radio ultra wideband systems with multiple receive antennas. For binary PPM modulations, we propose various combining/detection schemes derived by the generalized likelihood ratio criterion. These schemes first combine delayed versions of the waveforms received at the different antennas and then compute the energies of the resulting signal over intervals smaller than half the symbol period. The decision statistic is finally obtained by a linear combination of these energies. The proposed algorithms can be implemented using currently available technology. They outperform a detection scheme that simply combines the decision statistics obtained (at each antenna) by means of a conventional energy-based detector. Their advantage increases with the number of antennas