Signal space diversity based cooperative inter-cell downlink transmission for cell boundary users

In this paper, we present a novel cooperative downlink beamforming framework for the cell edge users based on the local channel state information (CSI). In the proposed scheme, the neighboring two base stations (BSs) transmit and remain silent alternatively via integrating signal space diversity into inter-cell time sharing. Pairwise error probability analysis demonstrates that the multi-cell spatial diversity gain can be achieved for each data stream. Thus the inter-cell links become beneficial rather than detrimental. For comparison, some existing practical cooperative beamforming strategies are also discussed, such as straightforward time sharing and distributed cooperative beamforming. Both theoretical analysis and simulation results confirm that the proposed scheme outperforms the existing relevant strategies. It is shown that in the interested range of noise powers, the proposed cooperative inter-cell scheduling can significantly improve the error performance in a distributed manner while maintaining the same multiplexing gain.