Robust mmWave/sub-THz multi-connectivity using minimal coordination and coarse synchronization

TL;DR

This paper proposes a simplified multi-connectivity scheme for mmWave/sub-THz networks that achieves macrodiversity and SNR gains with minimal coordination, using non-coherent transmission and space-time coding, validated through analysis and simulations.

Contribution

It introduces a novel multi-connectivity approach that extends non-coherent joint transmission with diversity and coding, reducing coordination needs while maintaining high performance.

Findings

Achieves macrodiversity and SNR gains with minimal infrastructure coordination.

Employs an Alamouti-like coding to recover performance close to optimal.

Validated through theoretical analysis and ray-tracing simulations.

Abstract

This study investigates simpler alternatives to coherent joint transmission for supporting robust connectivity against signal blockage in mmWave/sub-THz access networks. By taking an information-theoretic viewpoint, we demonstrate analytically that with a careful design, full macrodiversity gains and significant SNR gains can be achieved through canonical receivers and minimal coordination and synchronization requirements at the infrastructure side. Our proposed scheme extends non-coherent joint transmission by employing a special form of diversity to counteract artificially induced deep fades that would otherwise make this technique often compare unfavorably against standard transmitter selection schemes. Additionally, the inclusion of an Alamouti-like space-time coding layer is shown to recover a significant fraction of the optimal performance. Our conclusions are based on a statistical single-user multi-point intermittent block fading channel model that, although simplified, enables rigorous ergodic and outage rate analysis, while also considering timing offsets due to imperfect delay compensation. In addition, we validate our theoretical approach by means of deterministic ray-tracing simulations that capture the essential features of next generation mmWave/sub-THz communications.