Using amplify-and-forward relay for coverage extension in indoor environments

Abstract

Cooperative communication is a promising method for increasing the capacity and extending the coverage between a base station (BS) and a mobile user (MU) by using relays to exploit cooperative diversity. However, the existing literature mainly focuses on theoretical performance evaluation without experimental validation and, thus, fails to address the effects on real-world radio signal propagation. This research, therefore, aims to develop a prototype amplify-and-forward (AF) relay using software-defined radio (SDR) to evaluate the real-world performance of such a relay in improving coverage. The proposed relay is developed using the LabVIEW software and programmed on a National Instruments-Universal Software Radio Peripheral 2922 (NI-USRP 2922) SDR platform. The major merit of this entire communication setup is less expensive as the system uses a reprogrammable hardware. The measurements are performed indoors, and the signal strength or received power at the MU in cases with and without the relay is recorded. The results show that the received power performance and signal-to-noise ratio (SNR) at the user improve significantly when the AF relay is deployed compared to when direct link point-to-point transmission without the relay is used.