6 Questions About 6G

All mainstream network operators in New Zealand are steadily deploying 5G across the country. While we explore the scale of innovation and growth that 5G offers in almost all sectors of life, researchers around the world are already working on 6G – the sixth generation of mobile phone technology. This obviously raises at least six basic questions:

Do we really need 6G? That largely depends on the trend of how much data we, the users, exchange using our mobile devices. A network can only handle a limited amount of data sent or received by the users, which can be roughly packaged as ‘user demand’. In 2012, Ericsson predicted that user demand would increase exponentially over the next five years [1] – a prediction that later proved to be true. Interestingly enough, that exponential trend in growth will continue to be witnessed through to at least 2030, according to International Telecommunication Union’s (ITU) report on traffic estimates [2]. Future generations of mobile phone technology, like 6G, will add new capacity to the network for meeting the ever increasing user demand.

Why does user demand keep increasing? Firstly, user base around the world is expanding, with increasing population of users and rising number of mobile devices owned by a single user. Secondly, there are attractive applications that drain capacity. A recent research article [3] notes that two-thirds of the entire network traffic comprises of video streaming (through Netflix, YouTube, etc.). What we do on the network is increasingly data hungry. The days when mobile phones were used only for making voice calls are long gone!

How will 6G meet user demand? User demand can only be met by adding new capacity to the network. Capacity of a network largely depends on the availability of frequency bands that carry data. 6G will use larger bands at even higher frequencies for data transmission. While current 5G technology uses 3.5 GHz frequency bands, 6G will use frequencies in 1 THz range [4]. Although choosing to transmit at a higher frequency band sounds simple enough, there are a number of technical challenges that the research community is currently grappling with. For example, hardware devices that can support THz communications are not readily available at yet [5].

Who is building 6G? One of the earliest projects on developing 6G started at University of Oulu, Finland, in 2018 [6]. Since then a number of countries around the world including China, South Korea, Japan, etc. have taken different initiates towards developing 6G. The United States has issued experimental licenses for testing 6G in the THz frequency bands, formal allocation of which is expected to be discussed in the World Radiocommunication Conference (WRC) of 2023 [3].

When will it come out? 6G is scheduled to be rolled out in/after 2030. Its predecessor, 5G, was scheduled to roll out in 2020. As it turns out, there is a separate generation for every decade, starting with 1G that was introduced way back in the 1980s. But roll outs can be tricky. While we can access 5G now in some parts of New Zealand, the high frequencies intended for it (26GHz, 36GHz) are yet to be used. The roll out of 6G will also likely go through a transition of a relatively smaller increase in transmission frequency, followed by the full use of THz bands. The full-fledged use of the THz band is not expected before we are well into the 2030 decade.

Will 6G be harmful? A number of research articles can be found that address the health impact of high frequency 5G transmissions, and methods for measuring its radiation in our environment [7, 8]. While literature on wireless communication that uses THz band (which will be used by 6G) has remained available for quite some time [9], it will be interesting to see how wireless signals in the THz range will interact with human body when considered for use at a commercial scale. 6G signals are also expected to be characterized in terms of power density, a metric that is also used for assessing the impact of 5G.

These are still early days – we’ll have a lot to digest in the years to come.

References

1. “Bringing the Networked Society to Life” Annual Report, Ericsson, 2012.
2. ITU-R Report M.2370-0, “IMT Traffic Estimates for the Years 2020 to 2030”.
3. W.Jiang, B. Han, M. A. Habibi and H. D. Schotten, “The Road Towards 6G: A Comprehensive Survey”, IEEE Open Journal of the Communications Society, volume 2, 2021.
4. 1 Tera = 1000 Giga
5. Z. Chen, X. Ma, B. Zhang, Y. Zhang, Z. Niu, N. Kuang, W. Chen, L. Li and S. Li, “A Survey on Terahertz Communications”, China Communications, volume 16, 2019.
6. Oulu 6G Flagship Project, University of Oulu. Available at: https://www.oulu.fi/6gflagship/ 
7. D. Basu and S. F. Hasan, “Approximating Electromagnetic Exposure in Dense Indoor Environments”, 15th International Symposium on Wireless Communication Systems, 2018.
8. D. H. Gultekin and P. H. Siegel, “Absorption of 5G Radiation in Brain Tissue as a Function of Frequency, Power and Time”, IEEE Access, volume 8, 2020.
9. K-C. Huang and Z. Wang, “Terahertz Terabit Wireless Communication”, IEEE Microwave Magazine, volume 12, 2011.

Author: Faraz Hasan is a Senior Lecturer in Communication Engineering at Massey University, where he leads Telecommunication and Network Engineering research team.

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