Broadcast Channel Feedback in Multiple-Antenna Transmitter Cooperation Networks: Accuracy or Consistency?

We consider the use of broadcast feedback of channel state information (CSI) in multi-cell cooperative networks. The salient feature of this form of feedback lies in the exploitation of the broadcast nature of the wireless medium in order to convey CSI to all transmitters in contrast with other forms of feedback exchange mechanisms relying on inter-transmitter signaling. We show that this particular design approach for feedback naturally leads to a scalable partially distributed precoding framework for multi-cell MIMO networks. A model based on channel quantization is provided to assess the performance of such a system. The analysis exhibits a novel trade-off between feedback consistency and accuracy which is specific to the multi-transmitter cooperation scenario. The optimal trade-off is explored through analysis and numerical simulations.