Hierarchical space-time block codes with antenna subset selection for large MIMO systems

Millimiter wave (mmWave) systems require precoding/combining framework and large antennas arrays. Due to the hardware constraints, we need new hybrid architectures. If we are aiming to reduce cost and number of radio frequency (RF) chains, it is preferred to adopt a hybrid design using switches to multiple antennas, based on antenna subset selection with baseband combining. In this paper, we propose a new hierarchical Space-Time Block Codes (STBC) technique in order to design coding matrix in large Multiple Input Multiple Output (MIMO) systems. Given channel error estimate, combination of STBC with Antenna Selection (AS) makes the MIMO system robust. By introducing a practical algorithm for AS STBC, our system has the capability of selecting antenna subsets and switching RF channels. As a result, the manner in which the matrix block is fulfilled changes and the coding rate is varying. After modeling the channel by 64 sub-channels (MIMO 8×8), having each 12 coefficients, we validate our approach by presenting robust results obtained from the estimation of the coefficients using our proposed hierarchical coding matrix technique. Replacing AS scheme in the Hybrid Antenna Selection (HAS) by the approach combining STBC and AS, we present a Modified HAS that achieves the same performance as HAS algorithm.