Coherent Product Superposition for Downlink Multiuser MIMO

TL;DR

This paper extends product superposition techniques to coherent signaling in multiuser MIMO downlink channels, showing DoF gains across various antenna setups and SNR regimes with different decoding strategies.

Contribution

It introduces the use of product superposition with pilots in coherent signaling, broadening its applicability and demonstrating DoF gains in more configurations.

Findings

Product superposition achieves DoF gains in coherent MIMO broadcast channels.

Both interference cancellation and non-cancellation decoders are effective.

Simulation results confirm theoretical rate improvements.

Abstract

In a two-user broadcast channel where one user has full CSIR and the other has none, a recent result showed that TDMA is strictly suboptimal and a product superposition requiring non-coherent signaling achieves DoF gains under many antenna configurations. This work introduces product superposition in the domain of coherent signaling with pilots, demonstrates the advantages of product superposition in low-SNR as well as high-SNR, and establishes DoF gains in a wider set of receiver antenna configurations. Two classes of decoders, with and without interference cancellation, are studied. Achievable rates are established by analysis and illustrated by simulations.