Multiple-antenna multiple-relay system with precoding for multiuser transmission
Arash Talebi, Witold A. Krzymień · 2009
Multi-hop relaying will play a central role in next generation wireless systems. In this paper a novel relaying strategy that uses multiple-input multiple-output (MIMO) relays in a two-hop wireless network supporting multiuser transmission is proposed. The fixed relays linearly process the received signal, decode and forward it to multiple users. This relaying strategy employs MIMO spatial multiplexing to achieve high spectral efficiency and improve link capacity in cellular networks. In this paper the case when source (base station) and all the relays employ multiple antennas and each user has only one antenna is studied. New lower and upper bounds on the achievable sum rate for this architecture are derived. Zero-forcing dirty paper coding (ZF-DPC) at the base station is assumed and the direct link between the base station and users is neglected. We propose to jointly design precoding at the base station and linear processing at the relays to improve throughput subject to power constraints at the source and relay transmitters. The impact of multiple relaying on the achievable sum rate lower bound is investigated. The proposed lower bound improves on earlier sum rate lower bounds that were derived for simpler cases of relaying.