Performance analysis of multiple antenna systems with VQ-based feedback

We investigate vector quantization (VQ) methods for feeding back the channel information through a low-rate feedback channel in the context of multiple-antenna MISO systems. The performance of systems with VQ-based quantized beamforming is analyzed for the independent Rayleigh fading case. This requires finding the density of the squared inner-product between the optimum and the quantized beamforming vector, which is obtained by considering a simple approximation of the quantization cell. The approximate density function is used to lower bound the capacity loss due to quantization, the outage probability and the bit error probability.