[Paper Review] A Survey of 6G Wireless Communications: Emerging Technologies

Yang Zhao, Jun Zhao+4 more|arXiv (Cornell University)|Apr 18, 2020

Advanced Wireless Communication TechnologiesEngineering83 references19 citations

TL;DR

This survey identifies and analyzes key emerging technologies for 6G wireless communications, including index modulation, artificial intelligence, intelligent reflecting surfaces, and terahertz communications. It provides a comprehensive overview of their principles, integration potential, and performance benefits, offering a structured foundation for future 6G system design and research.

ABSTRACT

While fifth-generation (5G) communications are being rolled out around the world, sixth-generation (6G) communications have attracted much attention from both the industry and academia. Compared with 5G, 6G will have a wider frequency band, higher transmission rate, spectrum efficiency, greater connection capacity, shorter delay, wider coverage and stronger anti-interference capability, so as to meet the various network requirements for industries. In this paper, we present a survey of potential essential technologies in 6G. In particular, we will introduce artificial intelligence, intelligent surfaces, terahertz communications technologies in detail, while giving a brief introduction to other potential technologies, including visible light communications, Blockchain-enabled wireless network, advanced duplex and holographic radio.

Motivation & Objective

• To identify and synthesize the most promising emerging technologies expected to define 6G wireless networks.
• To provide a detailed technical analysis of four core technologies: index modulation, artificial intelligence, intelligent reflecting surfaces, and terahertz communications.
• To offer a concise overview of supplementary technologies such as visible light communication, blockchain, satellite integration, full-duplex, holographic radio, and network-in-box.
• To bridge the gap between visionary 6G predictions and actionable technical insights for researchers and industry practitioners.
• To establish a foundation for future research by summarizing current visions and technical directions in 6G system development.

Proposed method

• Systematic review and synthesis of existing research and vision papers on 6G wireless communications.
• In-depth technical explanation of index modulation, focusing on spectral and power efficiency through resource indexing (e.g., subcarriers, antennas, time slots).
• Analysis of artificial intelligence applications in 6G, particularly in optimizing network management, beamforming, and resource allocation via machine learning models.
• Examination of intelligent reflecting surfaces (IRS), including passive and active IRS, for dynamic channel control and coverage enhancement using reconfigurable surfaces.
• Technical survey of terahertz (THz) communications, emphasizing propagation challenges, high data rate potential (up to 1 Tbps), and use in short-range, high-capacity links.
• Brief but structured overview of supporting technologies: blockchain for decentralized security, satellite integration for global coverage, full-duplex for spectral efficiency, holographic radio for interference exploitation, and network-in-box for service-centric deployment.

Experimental results

Research questions

• RQ1 What are the key performance requirements driving the development of 6G wireless networks?
• RQ2 How do index modulation and intelligent reflecting surfaces enhance spectral efficiency and network reliability in 6G?
• RQ3 What are the technical challenges and opportunities associated with terahertz-band communications in 6G systems?
• RQ4 How can artificial intelligence and machine learning be integrated into 6G network control and optimization?
• RQ5 What role do emerging technologies like blockchain, holographic radio, and network-in-box play in shaping the architecture and security of 6G networks?

Key findings

• 6G is expected to achieve peak downlink data rates of at least 1 Tbps, with latency reduced to 0.1 ms and reliability reaching 99.99999%.
• Index modulation enables high spectral efficiency by encoding data in the indices of active subcarriers, antennas, or time slots, reducing hardware complexity.
• Intelligent reflecting surfaces (IRS) can enhance signal strength and coverage by dynamically reconfiguring wireless propagation environments, especially in non-line-of-sight scenarios.
• Terahertz communications offer ultra-high data rates (up to 1 Tbps) but face challenges due to high path loss and atmospheric absorption, limiting their use to short-range, line-of-sight links.
• Artificial intelligence is expected to play a central role in optimizing 6G networks through predictive beamforming, dynamic spectrum access, and self-organizing network functions.
• Blockchain technology enables decentralized, secure, and auditable network operations in 6G, particularly through smart contracts and distributed trust mechanisms in radio access networks.