Hybrid Precoding for mmWave MIMO Systems With Overlapped Subarray Architecture

Traditional precoding is incompatible with millimetre wave (mmWave) multiple input multiple output (MIMO) systems due to hardware costs and power consumption. As a result, hybrid precoding is being considered as a promising technology for balancing hardware complexity and system performance. This paper proposes a hybrid precoding technique for overlapped subarrays (OSA) architecture in mmWave MIMO systems. It exploits the OSA’s structure to decompose the hybrid precoding problem into a series of $L_{t}N_{s}/2$ subproblems and then solves them iteratively, where $L_{t}$ and $N_{s}$ are the numbers of RF chains and transmitted data streams, respectively. First, the proposed scheme determines the analog and digital precoding submatrices of each OSA iteratively and then constructs the analog and digital precoding matrices of the whole OSA architecture. The digital precoding submatrix of each OSA is determined from each vector in the OSA submatrix. The results show that the proposed hybrid precoding for the OSA architecture outperforms the successive interference cancellation (SIC)-based hybrid precoding for non-overlapped SA (NOSA) and provides performance close to the fully-connected (FC) spatially sparse hybrid precoding, despite requiring less hardware and computational complexities.