Outage Performance of Dual-Hop UWB Transmissions Using a Multiple-Antenna Relay with Antenna Selection versus Single-Antenna Relay Selection

Abstract

This paper presents one-way and two-way ultra-wideband (UWB) relay systems using a multiple-antenna relay with antenna selection and those using single-antenna relay selection. In particular, amplify-and-forward (AF) and detect-and-forward (DTF) relaying schemes are considered for these systems. The exact formulae for the end-to-end signal-to-noise ratio (SNR) outage probabilities of the one-way AF and one-way DTF relay systems are derived. In order to minimize these outage probabilities, the optimal power allocation strategies are presented. The SNR expressions for the received signals in the two-way AF and two-way DTF relay systems are derived to evaluate the system outage performance and to determine the corresponding optimal power allocation. Based on the above results, we quantify the effects of the number of antennas and the number of relays on the outage probabilities of the systems using the multiple-antenna relay with antenna selection and those using the single-antenna relay selection, respectively. We also compare such outage probabilities obtained with equal power allocation and the ones obtained with the aforementioned optimal power allocation strategies. Furthermore, the effect of spatial correlation at the multiple-antenna relay on the outage performance is studied. We find that in general, using the multiple-antenna relay with the antenna selection provides more outage gain than using the single-antenna relay selection for all the considered systems except the two-way DTF systems.