Multiple Antenna Assisted Hard Versus Soft Decoding-and-Forwarding for Network Coding Aided Relaying Systems

In this paper, we propose two types of new decoding algorithms for a network coding aided relaying (NCR) system, which adopts multiple antennas at both the transmitter and receiver. We consider the realistic scenario of encountering decoding errors at the relay station (RS), which results in erroneous forwarded data. Under this assumption, we derive decoding algorithms for both the base station (BS) and the mobile station (MS) in order to reduce the deleterious effects of imperfect decoding at the RS. We first propose a decoding algorithm for a hard decision based forwarding (HDF) system. Then, for the sake of achieving further performance improvements, we also employ soft decision forwarding (SDF) and propose a novel decoding error model, which divides the decoding error pattern into two components: hard and soft errors. Given this error model, we then modify the HDF decoder for employment in SDF systems. Our simulation results show that the proposed algorithms provide substantial performance improvements in terms of the attainable packet error rate as a benefit of our more accurate decoding error model.