Complex Rotation-based Linear Precoding for Physical Layer Multicasting and SWIPT

TL;DR

This paper introduces a unified complex rotation-based precoding method for MIMO systems that enhances spectral efficiency in multicasting and SWIPT, outperforming existing solutions in rate and energy transfer with reduced complexity.

Contribution

It presents a novel, general precoding approach using complex rotation matrices applicable to multiple MIMO systems, simplifying design and improving performance.

Findings

Outperforms state-of-the-art solutions by 20-30% in transmission rates.

Achieves higher rate-energy regions in SWIPT scenarios.

Reduces computational complexity compared to existing methods.

Abstract

With the goal of improving spectral efficiency, complex rotation-based precoding and power allocation schemes are developed for two multiple-input multiple-output (MIMO) communication systems, namely, simultaneous wireless information and power transfer (SWIPT) and physical layer multicasting. While the state-of-the-art solutions for these problems use very different approaches, the proposed approach treats them similarly using a general tool and works efficiently for any number of antennas at each node. Through modeling the precoder using complex rotation matrices, objective functions (transmission rates) of the above systems can be formulated and solved in a similar structure. Hence, this approach simplifies signaling design for MIMO systems and can reduce the hardware complexity by having one set of parameters to optimize. Extensive numerical results show that the proposed approach outperforms state-of-the-art solutions for both problems. It increases transmission rates for multicasting and achieves higher rate-energy regions in the SWIPT case. In both cases, the improvement is significant (20%-30%) in practically important settings where the users have one or two antennas. Furthermore, the new precoders are less time-consuming than the existing solutions.