Feedback bit allocation in a gateway channel

This paper studies feedback bit allocation in a gateway channel where multiple source and destination pairs communicate with the aid of a single decode-and-forward (DF) relay. Assuming zero-forcing precoding at relay, we propose a feedback bits allocation strategy based on the lower bound of relay-to-destination achievable sum rate when destinations share a limited feedback channel. The proposed feedback bit sharing strategy allocates more feedback bits to the destination who has a better source-to-relay achievable rate in the high SNR region. Numerical results show that our proposed feedback bits allocation strategy achieves a meaningful gain over the equal feedback allocation in terms of sum ergodic rate, especially in the high SNR region.