Iterative Signal Detection Based on MSD-CG Method for Uplink Massive MIMO Systems

The multiple-input multiple-output (MIMO) wireless system can either be massive or conventional “small-scale” ones. It has been verified that the massive MIMO technology has a great potential to improve transmission range, spectral efficiency, and coverage compared to conventional MIMO. For realistic antenna configurations systems, there is an increase in the computational complexity associated with signal detection in massive MIMO systems. Several theoretical iterative techniques have been proposed to balance the computational complexity and performance in massive MIMO systems. However, most of these methods have very slow convergence rate. Therefore, we employ the multiple search direction conjugate gradient (MSD-CG) method in massive MIMO uplink systems to reduce the data detection complexity and enhance the performance. The efficiency of the proposed method has been improved by a projection technique that requires a search direction in each sub-domain rather than forming all search directions conjugate to each other. In this paper, we compare the proposed approach to the approximate and exact methods. Our results indicate that the proposed algorithm with realistic antenna configurations is superior to the existing methods for large-scale MIMO systems.