Codebook Design and Performance Analysis of Quantized Beamforming under Perfect and Imperfect Channel State Information

Abstract

Abstract-This paper presents a codebook design to multiple transmit and multiple receive antenna system with quantized feedback channel. The codebook design is based on trigonometrical expressions that give a quasi-orthogonal structure to the codes. The codebook is designed to a specific number of transmit antennas and can easily be adapted to different number of feedback bits. An instantaneous signalto-noise ratio analysis is performed which is used to optimize the codebooks. An upper bound on the bit error rate (BER) performance for the proposed scheme is provided as well. We also investigate the system performance under more realistic conditions, and for this purpose we consider a time-varying and spatially-correlated channel model. We compare the BER performance of the proposed scheme with other closed-loop codebook-based schemes. Results show that the proposed scheme outperforms other good schemes in terms of array gain.Index Terms-MIMO, beamforming, quantized feedback, BER and channel estimation.