Diversity gain of millimeter-wave massive MIMO systems with distributed antenna arrays

Abstract

Abstract This paper is concerned with diversity gain analysis for millimeter-wave (mmWave) massive MIMO systems employing distributed antenna subarray architecture. First, for a single-user mmWave system in which the transmitter and receiver consist of K t and K r subarrays, respectively, a diversity gain theorem is established when the numbers of subarray antennas go to infinity. Specifically, assuming that all subchannels have the same number of propagation paths L, the theorem states that by employing such a distributed antenna subarray architecture, a diversity gain of K r K t L−N s +1 can be achieved, where N s represents the number of data streams. This result means that compared to the co-located antenna architecture, using the distributed antenna subarray architecture can scale up the diversity gain proportionally to K r K t . The analysis of diversity gain is then extended to the multiuser scenario as well as the scenario with conventional partially connected radio-frequency structure in the literature. Simulation results obtained with the hybrid analog/digital processing corroborate the analysis results and show that the distributed subarray architecture indeed yields a significantly better diversity performance than the co-located antenna architectures.

Keywords

• Millimeter-wave communications
• Massive MIMO
• Diversity gain
• Multiplexing gain
• Diversity-multiplexing trade-off
• Distributed antenna subarrays