A High-Diversity Transceiver Design for MISO Broadcast Channels

TL;DR

This paper introduces a mixture transceiver architecture for MISO broadcast channels that achieves full diversity order and improves outage performance by combining user grouping, superposition coding, and zero-forcing beamforming.

Contribution

The paper derives new closed-form lower bounds on achievable rates and demonstrates that the mixture scheme attains full diversity and enhances multiplexing gain in MISO broadcast channels.

Findings

Achieves full diversity order similar to single-user MISO systems.

Opportunistically increases multiplexing gain with proper user grouping.

Outperforms conventional transceiver designs in outage probability.

Abstract

In this paper, the outage behavior and diversity order of the mixture transceiver architecture for multiple-input single-output broadcast channels are analyzed. The mixture scheme groups users with closely-aligned channels and applies superposition coding and successive interference cancellation decoding to each group composed of users with closely-aligned channels, while applying zero-forcing beamforming across semi-orthogonal user groups. In order to enable such analysis, closed-form lower bounds on the achievable rates of a general multiple-input single-output broadcast channel with superposition coding and successive interference cancellation are newly derived. By employing channel-adaptive user grouping and proper power allocation, which ensures that the channel subspaces of user groups have angle larger than a certain threshold, it is shown that the mixture transceiver architecture achieves full diversity order in multiple-input single-output broadcast channels and opportunistically increases the multiplexing gain while achieving full diversity order. Furthermore, the achieved full diversity order is the same as that of the single-user maximum ratio transmit beamforming. Hence, the mixture scheme can provide reliable communication under channel fading for ultra-reliable low latency communication. Numerical results validate our analysis and show the outage superiority of the mixture scheme over conventional transceiver designs for multiple-input single-output broadcast channels.