Low Complexity Transceivers in Multiuser Millimeter-Wave Beamspace-MIMO Systems

We present a new millimeter-wave (mm-wave) transmission scheme that combines beamspace Multi-Input Multi-Output (B-MIMO) communications and beam selection techniques to achieve near-optimal performances with a low hardware-complexity transceiver. The use of mm-wave frequencies in MIMO systems is afflicted by high complexity and costs, caused by the high dimensional signal space. The proposed scheme is characterized by a reduced radio-frequency (RF) complexity, achieved through beam selection, while leading to near-optimal performances. The benefits of the proposed scheme are evaluated via performance computations, comparisons of numbers of required RF chains and a joint sum-rate and complexity metric that shows the trade-off between spectral and power efficiency. The analytical and numerical results presented in the paper show that the proposed scheme offers an improved power efficiency with respect to the full system with a realistic low-cost approach.