A Differential Codebook with Adaptive Scaling for Limited Feedback MU MISO Systems

In this letter, we propose an adaptive scaling technique for a differential codebook (DCB) in multiuser (MU) multiple-input single-output (MISO) systems operating under spatially and temporally correlated channels. The proposed adaptive scaling technique depends on the mean channel variation due to spatial/temporal correlation in the channel and the mean quantization error associated with the previous feedback, hence avoiding the need to periodically reset the codebook. The performance of the proposed DCB is evaluated for both zeroforcing beamforming (ZFBF) and signal-to-leakage-and-noise ratio beamforming (SLNR BF) schemes. Simulation results show the effectiveness of the proposed adaptive scaling and also the superiority of the SLNR BF scheme over the ZFBF scheme.