Efficient Limited Feedback Schemes for Network MIMO Systems.

In this paper, a feedback channel selection scheme and a bit allocation scheme are proposed for a network MIMO system with limited feedback. The feedback channel selection is performed by comparing the gain of each channel vector with a certain threshold. In particular, we derive an optimal threshold that maximizes a utility function, which is defined in terms of the expected rate of each user. In addition, we also develop an unequal feedback bit allocation scheme over the selected set of channels to further improve the system performance. It is shown that the joint feedback channel selection and bit allocation can provide significant gain in the average sum rate for a network MIMO system with limited feedback.