Selection of the Coordination Strategy in the Network MIMO Downlink

Network MIMO or distributed MIMO is one promising strategy to increase the data rates in future cellular communication systems. However, well-known schemes like linear preequalization or Tomlinson-Harashima precoding for handling the multiuser interference assume full coordination (via some centralized processing) between the base stations. This approach causes significant traffic in the (wired) backhaul. In this paper, decentralized strategies with partial coordination are considered. A selection algorithm is presented, which, given the actual MIMO channel, automatically chooses the amount of coordination which is necessary to achieve a predefined performance. The trade-off between the achievable reduction in backhaul signaling and the required signal-to-noise ratio to not exceed a tolerated bit error rate is discussed. The proposed strategies are covered by means of numerical simulations.