Forget 5G, global race to 6G has already begun

L Anantharam 2G mobile technology, introduced in '90s, made the transition to digital communications. It introduced the SMS feature and ten times higher speed compared to 1G. 3G mobile technology was introduced after the year 2000 and this technology made the internet service available on mobile devices. This technology supports higher speeds compared to 2G technology. 4G technology entered the wireless communication arena after 2010 and it brought a large increase in speed and bandwidth deploying LTE (Long Term Evolution) technology and starting the smartphone revolution. Further increase in speed and bandwidth upto ten times is brought by 5G which started in 2019. This technology connects things and people. It has thrown the possibility of connecting smart devices in all domains of activity (smartphones, smart TVs, smart cars, smart appliances) to create the Internet of Things (IoT).

Change from one generation of technology to the next generation one takes ten years. Vision, invention, PoC (Proof of Concept) in which initial prototypes are built, standardization, trials (putting to test in the real world scenario) and commercialisation are the various stages the new technology undergoes before it matures in these ten years. The work on 6G technology has already started. It is in between the vision and invention stage now and some of the key building blocks are in the PoC stage. 6G will emerge as key wireless technology in the later part of the current decade.

6G is technology for the future and is on anvil. The stimulus for 6G is software, AI (Artificial Intelligence) and ML (Machine Learning). It is going to be an important innovation and is going to change the quality of our life, the way we conduct business and interact with devices. This technology will lead to the merger of physical and virtual worlds. It is going to connect humans and machines. It will be more than the IoT started by 5G. IMT (International Mobile Telecommunications) 2030 defines 6G standards. Potential 6G requires significantly advanced antenna systems, modulation techniques, multiplexing technologies and network devices to allow massive data output with low latency. While 4G uses 4x4 MIMO (Multi Input and Multi Output) and 5G uses around 200 antenna elements, 6G will use upto 1024 antenna elements. This technology will lead to the convergence of satellite communications with terrestrial communications. Holographics, ubiquitous use of drones and digital twinning (A digital twin is a virtual representation that serves as the real time digital counterpart of a physical object or process) are some of the applications of this technology. The important areas that will benefit from this technology are smart devices, self-driving cars, flying cars and robots.

5G is the launch pad for 6G. 6G will have better KPIs (Key Performance Indicators) compared to 5G. It will be built upon the infra of 5G. 5G is evolving based on 3 GPP (3rd Generation Partnership Project) standards of release 15, 16 and 17 (which are foundation technologies for 5G) and release 18, 19 and 20 (which define 5G advanced). Host of features will be built as 5G passes through these releases of standards. At the stage of 3GPP release 21, 6G will be getting defined.

Some of the topics considered for long term research in 5G advanced and 6G are:

n AI/ML data driven design

n Full duplex

n Higher mm wave

n Terahertz bands

n Reconfigurable Intelligent surfaces (RIS) for coverage extension and improving energy efficiency.

n Green networks

n RF sensing

n Extreme disaggregation

n Cloud/core RAN (Radio Access Network)

n Convergence

n Ultra secure communications

n Next - gen foundational technologies: waveforms, multiplexing, channel coding, MIMO

similar to 5G, 6G would be built on software architecture with a focus on OpenSource. Open RAN and Edge computing will continue to be adopted by 6G. While 5G offers less than 1 millisecond latency, 6G offers less than 0.1 millisecond latency. It will operate in the following frequency bands:

n Sub 7GHz band for the long distance coverage

n 7-20GHz band which has wide bandwidth for covering the places that are crowded, for deep coverage

n mm wave- 28, 39, 60 GHz

n Sub-THz (90 GHz to 300 GHz) for peak data rates of 100 Gbps in the short range, for advance sensing

The key enablers in the path forward towards 6G technology are:

n AI/ML powered End to End communications

n Spectrum expansion and sharing: 6G will operate in licensed, unlicensed and shared spectrum

n New radio designs

n Integrating non communications (positioning and sensing) into communication systems

n Merging of worlds (physical, digital, virtual) leading to new user experience of metaverse

n Scalable network architecture

n Communication resiliency with robust networks tolerant to failures and attacks and multifaceted trust and configurable security and post quantum technology security

6G will have better coverage and power efficiency. Device size will be optimised. This technology will continue to improve end to end system energy efficiency in tune with the objectives of green telecom. Duplexing schemes will continuously be evolved for the next level of latency reduction, broad coverage and improved spectral efficiency. The key enablers for a full duplex air interface are:

n Spatial isolation

n Frequency isolation

n Beam isolation

n Digital/ analog self interference mitigation

Way forward

The leap from 5G to 6G will be shorter than the previous network leaps due to the increasing speed of technological advancements in networking. With speeds that are 50 times faster than 5G, 6G will be more disruptive than 5G. Samsung (South Korea) has already started working on 6G and is planning for its rollout in 2028. AT&T (USA), Huawei and LG also are working on 6G technology. In October 2021, Secretary DOT asked CDOT to work on 6G technology in order to catch up with the global market in time. The Central governament expects India to take the lead in 6G technology so that it can set direction for the whole world as India is called a nation of talents. As we develop technology and as it matures, digital inclusiveness, affordability to common man and availability everywhere should not be lost sight of.

(The author is a former Advisor, Department of Telecommunications (DoT), Government of India)