A Survey on MIMO Transmission with Discrete Input Signals: Technical Challenges, Advances, and Future Trends

TL;DR

This survey comprehensively reviews MIMO transmission techniques with discrete input signals, highlighting recent advances, challenges, and future trends, especially for 5G and multiuser systems, emphasizing practical design considerations.

Contribution

It provides the first unified framework for low complexity MIMO transmission schemes suitable for massive MIMO in 5G, and discusses adaptive strategies based on channel conditions.

Findings

Unified low complexity transmission framework for massive MIMO

Adaptive transmission strategies based on channel conditions

Extensive survey of multiuser MIMO transmission designs

Abstract

Multiple antennas have been exploited for spatial multiplexing and diversity transmission in a wide range of communication applications. However, most of the advances in the design of high speed wireless multiple-input multiple output (MIMO) systems are based on information-theoretic principles that demonstrate how to efficiently transmit signals conforming to Gaussian distribution. Although the Gaussian signal is capacity-achieving, signals conforming to discrete constellations are transmitted in practical communication systems. As a result, this paper is motivated to provide a comprehensive overview on MIMO transmission design with discrete input signals. We first summarize the existing fundamental results for MIMO systems with discrete input signals. Then, focusing on the basic point-to-point MIMO systems, we examine transmission schemes based on three most important criteria for communication systems: the mutual information driven designs, the mean square error driven designs, and the diversity driven designs. Particularly, a unified framework which designs low complexity transmission schemes applicable to massive MIMO systems in upcoming 5G wireless networks is provided in the first time. Moreover, adaptive transmission designs which switch among these criteria based on the channel conditions to formulate the best transmission strategy are discussed. Then, we provide a survey of the transmission designs with discrete input signals for multiuser MIMO scenarios, including MIMO uplink transmission, MIMO downlink transmission, MIMO interference channel, and MIMO wiretap channel. Additionally, we discuss the transmission designs with discrete input signals for other systems using MIMO technology. Finally, technical challenges which remain unresolved at the time of writing are summarized and the future trends of transmission designs with discrete input signals are addressed.