Half-duplex relaying over slow fading multiple access channel

This paper investigates the half-duplex (HD) relaying in the slow fading Multiple Access Channel (MAC) based on the generalized quantize-and-forward (GQF) scheme. Relay listens to the channel in the first slot of the transmission block and cooperatively transmits to the destination in the second slot. The achievable rate regions of the discrete memoryless HD-MARC and the corresponding additive white Gaussian noise (AWGN) channel have been established first. Based on the achievable rates, the outage probability and expected sum rate are characterized as the performance measure of the slow fading channel. It is shown that when the relay has no access to the channel state information (CSI) of the relay-destination link, the GQF scheme outperforms other relaying schemes, e.g., compress-and-forward (CF), decode-and-forward (DF) and amplify-and-forward (AF). In addition, for a MAC with heterogeneous user channels and quality-of-service (QoS) requirements, the individual outage probability and expected sum rate of the GQF scheme are also obtained and shown outperform the CF scheme.