Distributed MIMO for Cellular Networks with Multihop Transmission Protocols

We consider the downlink in a MIMO cellular network utilizing two-hop transmission protocols with fixed infrastructure relay stations to enhance coverage and data rates in a cell. We investigate the potential of relaying protocols in the case when a mobile station is in the communication range of two relays but not in the range of the base station. Since the relays are mounted at fixed positions we assume that the base station has knowledge about the channels to the relays which enables spatial preceding of the transmit data. We show that in the first hop the use of MIMO broadcast coding techniques, where the base station transmits only a subset of the data which is intended for the mobile station to each relay, has a superior performance compared to a MIMO multicast, where the whole data is transmitted to both relays.