Multiuser Two-Way Filter-and-Forward Relaying for Ultra-Wideband Communications

Abstract-In this paper, a multiuser two-way filter-and-forward relaying scheme for wireless communication over wideband channels is considered. We propose pre/post-rake processing in conjunction with optimized filtering at the relay to reduce the signal processing burden at the source and destination nodes. Two relay filter design problem formulations are introduced, namely (a) a convex optimization problem formulation with closed-form solutions and (b) the more general case, which is a non-convex problem solvable via an alternating optimization algorithm. For both design alternatives widely linear formulations are devised. The presented numerical results demonstrate the capability of the proposed designs to establish reliable two-way communication links between nodes with limited signal processing power and in the absence of a direct link

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