The Magic of Superposition: A Survey on Simultaneous Transmission Based Wireless Systems

TL;DR

This survey explores how superposition in wireless systems enables simultaneous transmission, enhancing scalability, security, and efficiency in IoT and distributed networks by leveraging interference rather than avoiding it.

Contribution

It systematically reviews and classifies existing literature on superposition-based wireless techniques, highlighting their connections and potential benefits for future IoT applications.

Findings

Superposition enables scalable and secure wireless communication.

Simultaneous transmission reduces latency and energy consumption.

Applications include NOMA, federated learning, and network coding.

Abstract

In conventional communication systems, any interference between two communicating points is regarded as unwanted noise since it distorts the received signals. On the other hand, allowing simultaneous transmission and intentionally accepting the interference of signals and even benefiting from it have been considered for a range of wireless applications. As prominent examples, non-orthogonal multiple access (NOMA), joint source-channel coding, and the computation codes are designed to exploit this scenario. They also inspired many other fundamental works from network coding to consensus algorithms. Especially, federated learning is an emerging technology that can be applied to distributed machine learning networks by allowing simultaneous transmission. Although various simultaneous transmission applications exist independently in the literature, their main contributions are all based on the same principle; the superposition property. In this survey, we aim to emphasize the connections between these studies and provide a guide for the readers on the wireless communication techniques that benefit from the superposition of signals. We classify the existing literature depending on their purpose and application area and present their contributions. The survey shows that simultaneous transmission can bring scalability, security, low-latency, low-complexity and energy efficiency for certain distributed wireless scenarios which are inevitable with the emerging Internet of things (IoT) applications.