Rate-Splitting Multiple Access: Fundamentals, Survey, and Future Research Trends

Yijie Mao, Onur Dizdar, Bruno Clerckx, Robert Schober, Petar Popovski, H. Vincent Poor

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Rate-splitting multiple access (RSMA) has emerged as a novel, general, and powerful framework for the design and optimization of non-orthogonal transmission, multiple access (MA), and interference management strategies for future wireless networks. By exploiting splitting of user messages as well as non-orthogonal transmission of common messages decoded by multiple users and private messages decoded by their corresponding users, RSMA can softly bridge and therefore reconcile the two extreme interference management strategies of fully decoding interference and treating interference as noise. RSMA has been shown to generalize and subsume as special cases four existing MA schemes, namely, orthogonal multiple access (OMA), physical-layer multicasting, space division multiple access (SDMA) based on linear precoding (currently used in the fifth generation wireless network–5G), and non-orthogonal multiple access (NOMA) based on linearly precoded superposition coding with successive interference cancellation (SIC). Through information and communication theoretic analysis, RSMA has been shown to be optimal (from a Degrees-of-Freedom region perspective) in several transmission scenarios. Compared to the conventional MA strategies used in 5G, RSMA enables spectral efficiency (SE), energy efficiency (EE), coverage, user fairness, reliability, and quality of service (QoS) enhancements for a wide range of network loads (including both underloaded and overloaded regimes) and user channel conditions. Furthermore, it enjoys a higher robustness against imperfect channel state information at the transmitter (CSIT) and entails lower feedback overhead and complexity. Despite its great potential to fundamentally change the physical (PHY) layer and media access control (MAC) layer of wireless communication networks, RSMA is still confronted with many challenges on the road towards standardization. In this paper, we present the first comprehensive tutorial on RSMA by providing a survey of the pertinent state-of-the-art research, detailing its architecture, taxonomy, and various appealing applications, as well as comparing with existing MA schemes in terms of their overall frameworks, performance, and complexities. An in-depth discussion of future RSMA research challenges is also provided to inspire future research on RSMA-aided wireless communication for beyond 5G systems.

Original languageEnglish (US)
Pages (from-to)1
Number of pages1
JournalIEEE Communications Surveys and Tutorials
DOIs
StateAccepted/In press - 2022

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

Keywords

  • 5G mobile communication
  • Interference
  • Multiaccess communication
  • NOMA
  • Radio transmitters
  • Rate-splitting (RS)
  • Time-frequency analysis
  • Wireless communication
  • beyond 5G (B5G)
  • interference management
  • multiple-input multiple-output (MIMO)
  • next generation multiple access
  • non-orthogonal transmission
  • rate-splitting multiple access (RSMA)

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