BDMA for Millimeter-Wave/Terahertz Massive MIMO Transmission with Per-Beam Synchronization

TL;DR

This paper introduces a novel beam division multiple access scheme with per-beam synchronization for wideband mmWave/THz massive MIMO, significantly reducing delay and Doppler spreads and improving system performance in mobility scenarios.

Contribution

It proposes a physically motivated beam domain channel model and a new per-beam synchronization method tailored for mmWave/THz massive MIMO systems, enhancing synchronization and rate performance.

Findings

Effective delay and Doppler spreads are reduced by the number of user antennas.

Simulation confirms improved ergodic rates in mobility scenarios.

Beam scheduling optimizes system throughput.

Abstract

We propose beam division multiple access (BDMA) with per-beam synchronization (PBS) in time and frequency for wideband massive multiple-input multiple-output (MIMO) transmission over millimeter-wave (mmW)/Terahertz (THz) bands. We first introduce a physically motivated beam domain channel model for massive MIMO and demonstrate that the envelopes of the beam domain channel elements tend to be independent of time and frequency when both the numbers of antennas at base station and user terminals (UTs) tend to infinity. Motivated by the derived beam domain channel properties, we then propose PBS for mmW/THz massive MIMO. We show that both the effective delay and Doppler frequency spreads of wideband massive MIMO channels with PBS are reduced by a factor of the number of UT antennas compared with the conventional synchronization approaches. Subsequently, we apply PBS to BDMA, investigate beam scheduling to maximize the achievable ergodic rates for both uplink and downlink BDMA, and develop a greedy beam scheduling algorithm. Simulation results verify the effectiveness of BDMA with PBS for mmW/THz wideband massive MIMO systems in typical mobility scenarios.