Short Packet Communications for Relay Systems With Co-Channel Interference at Relay: Performance Analysis and Power Control

Abstract

In this paper, we evaluate short packet communication (SPC) for a cooperative system where one relay assists data transmission between one multi-antenna source and one single antenna destination with the presence of co-channel interference at the relay. Two transmission schemes, i.e., transmit antenna selection (TAS) scheme and beamforming scheme (BS), are considered. Based on metric of SPC, we derive the average block error rate (BLER) for the system in asymptotic and closed-form expressions for both schemes. In addition, a solution of optimal power allocation (OPA) to maximize end-to-end effective system throughput is proposed. Effects of parameters such as total transmit power, number of the source's antennas, number of co-channel interference, and packet length on the performance of the system are evaluated. Finally, the results reveal that the performance of the OPA scheme outperforms that of the benchmark scheme, i.e., equal power allocation solution, in terms of BLER and the effective throughput for both the TAS and BS schemes. Moreover, the performance of the system reaches to saturation value with more antennas at the source. The findings indicate that the TAS and BS schemes have the same performance in terms of both the BLER and the effective throughput.INDEX TERMS block error rate, cooperative system, co-channel interference, short packet communications. I. INTRODUCTIONRecently, short packet communication (SPC) has been considered as an important technique for achieving low latency in wireless communication systems, and it has been widely studied in literature. Several scenarios such as cognitive radio networks [1], device-to-device (D2D) networks [2], unmanned-aerial-vehicle (UAV) networks [3,4], relaying systems [5,6,7] have been investigated in SPC systems.Furthermore, many applications where the transmitter and destination nodes cannot communicate directly with each other. Relaying communication is a technique in wireless communication where an intermediate device is used to forward data packets between the transmitter and the receiver [8,9]. The relaying device, also known as a relay node or relay station, receives the information from the transmitter and re-transmits it to the receiver. Two well-known protocols such as decode-and-forward (DF), and amplify-and-forward (AF) [10,11] have been used in cooperative networks. An evaluation of the AF relay system performance with taking into account interference at the relay was discussed in [12]. Inspired by [12], outage performance of an AF system under