User Allocation and Precoder Design for Coordinated Relaying

Relays are used in the current standards to enhance the cell throughput and coverage. Often, the relays are evaluated without considering the overhead involved in providing the relay with the data prior to the transmission. In this paper, we evaluate the system performance by considering the duplexing loss with over- the-air transmission (OTA) for relay with decode and forward as the relaying protocol. We demonstrate that the benefit of relays can be even detrimental if the in-band signaling needs are not properly accounted for. We assume a single-cell system extended with a single multi-antenna relay station serving single-antenna terminals. The system design objective is to allocate the users between the networks nodes and design their precoders such that the total transmit power is minimized while satisfying given user rate constraints.