Design of modified reduced dimensional subspace channel feedback codebook for massive mimo system

Abstract

The use of Lens antenna array with millimeter wave massive MIMO (multiple-input-multiple-output) system remarkably reduces the number radio frequency chains, high data rates are possible if the dimension of the equivalent channel is reduced after the beam selection. In frequency division duplex system codebooks are used to feedback equivalent channel to base station; however, no dedicated codebooks are available for LAA millimeter wave systems. In order to overcome the drawback, a proposed method is implemented such as modified reduced-dimensional sub-space codebook (M-RDSC) for millimeter wave massive MIMO systems. In the Proposed work, angle coherence time is used to build high dimensional vectors in the channel subspace, thereby these vectors are used to develop modified reduced dimensional sub-space codebook for feedback channel in millimeter wave massive MIMO system by taking the advantage of lens and beam selector. Finally, the equivalent channel aims to show performance through the use of the proposed M-RDSC and feedback to Base Station. The proposed system shows that the feedback overhead is made proportional to a few dominant paths per user. The overall performance of the proposed method is computed with the help of MATLAB R2018b version.