Closed-loop hybrid MIMO system with joint transmit antenna and mode selection based on capacity maximization

We present a new hybrid multiple input multiple output (MIMO) system combining spatial multiplexing and transmit diversity at different levels. The inner core of the transmit processing is responsible for space-time coding with variable rate-diversity control. The outer core is composed of two (coarse) precoding matrices acting as transmit antenna and mode selection matrices. Exploiting the structure of these selection matrices, a capacity maximizing selection criterion is proposed to optimize the hybrid transmission mode jointly with the transmit antenna mapping. Simulation results show that the proposed hybrid system offers significant capacity gains over its open-loop counterpart and outperforms pure antenna selection and pure mode selection based systems.