Channel Feedback Optimization for Network MIMO Systems

We investigate channel feedback optimization for network multiple-input-multiple-output (MIMO) systems. We consider feedback channel selection to exploit channel asymmetry inherent to network MIMO systems and consider feedback bit allocation, which allows an unequal number of feedback bits to be allocated to users according to the selected channel condition. We derive the upper bound of the expected rate loss due to channel selection and quantization and propose two algorithms referred to as successive algorithm and iterative algorithm, which jointly optimize the channel selection and bit allocation. Through computer simulations, we show that the proposed algorithms provide a significant amount of performance gain with greatly reduced complexity, compared with an exhaustive search.