An enhanced feedback method for coordinated multiple point joint transmission

Coordinated Multi-point Joint transmission with ideal channel state information can yield significant performance improvement due to coordinate inter-cell inferences, however the performance gains would be distinctly impacted with imperfect channel state information. In this paper, we show how downlink CoMP JT can be supported by an enhanced feedback method with reasonable feedback overhead. The feedback is quantized using code book based vector-quantization for the per-cell CSI feedback and scalar-quantization for additional inter-cell relative CSI feedback (i.e., relative phase and/or amplitude). The CoMP-JT performance with the enhanced feedback can acquire almost similar gains as ideal CSI feedback.