Alternate Distributed Beamforming for Buffer-Aided Multi-Antenna Relay Systems

TL;DR

This paper revisits the alternate distributed beamforming scheme for buffer-aided multi-antenna relay systems, providing theoretical throughput analysis and demonstrating significant performance improvements over existing policies.

Contribution

It introduces a fixed scheduling ADB scheme that does not require instantaneous CSI and analyzes its throughput in Rayleigh fading environments.

Findings

The ADB scheme significantly improves achievable throughput compared to existing policies.

Increasing antennas at relays yields better throughput gains than adding more single-antenna relays.

Theoretical throughput expressions are validated through simulations.

Abstract

In this paper, link selection is investigated in half-duplex (HD) dual-hop cooperative systems with multiple antennas at the relays. Alternate distributed beamforming (ADB) scheme is revisited for buffer-aided multi-antenna relay systems, in which the relays are divided into two groups, with one group receiving the same information broadcast from the source and the other group transmitting the common messages to the destination via distributed beamforming in each time slot. It is worth noting that the relays used for reception and transmission are determined without the need of instantaneous channel state information (CSI). Theoretical analysis of the achievable throughput of the proposed scheme in Rayleigh fading is provided and the approximate closed-form expressions are derived. Simulation results are given to verify the theoretical analysis. Through numerical results, it is shown that compared with existing link selection policies, the fixed scheduling ADB scheme achieves a significant improvement in achievable throughput. It is also shown that for the ADB scheme, the throughput performance of increasing the number of antennas equipped at each relay is better than that of increasing the number of relays equipped with a single antenna when the total number of antennas at the relays is fixed.