On the Value of Coherent and Coordinated Multi-Cell Transmission

Coordinated multi-cell processing facilitates multi-user preceding techniques across distributed base station (BS) antenna heads. This paper evaluates the performance of different coordinated multi-cell transmission methods with several channel allocation algorithms in different scenarios with varying inter- cell interference. A generalised method for joint design of linear transceivers with coordinated multi-cell processing subject to per-BS power constraints is provided for single antenna receivers. The method can accommodate a variety of scenarios from coherent multi-cell beamforming across a large virtual multiantenna broadcast channel to single-cell beamforming with inter-cell interference coordination and channel allocation. The system optimisation objectives are weighted SINR maximisation across all the transmitted data streams and weighted sum rate maximisation. The numerical examples demonstrate the value of the coherent multi-cell beamforming, which greatly outperforms the non-coherent cases especially at the cell edge. The coordinated single-cell transmission with interference avoidance and dynamic user allocation is also shown to perform relatively well with a partial spatial loading.