Linear Relaying Scheme for MIMO Relay System With QoS Requirements

In this letter, we address the problem of fulfilling quality-of-service (QoS) requirements in a multiple-input multiple-output (MIMO) relay system, where a set of target signal-to-noise ratios (SNRs) should be attained on different substreams. By solving a two-step optimization problem, we obtain a power-efficient relaying scheme that can make the SNR requirements asymptotically fulfilled. A simple relay selection method is also proposed such that the relay-power consumption can be largely reduced when there is a large number of relays.