The sixth generation of mobile communication networks, or 6G, is generating a lot of interest these days. It presents novel, ambitious, and futuristic use cases that will require much more than just communications.

What are the shortcomings of 5G networks?

Several bold and futuristic use case scenarios were outlined by the IMT 2020 during the development of 5G networks. To facilitate applications like remote surgery, autonomous driving, and numerous others, contrasting requirements—namely, high throughput and low latency—were required.

It poses extremely difficult requirements for the physical layer (PHY). For those applications to have the flexibility they required, a very creative PHY was required.

On the other hand, the standardization process that led to the 5G NR can be seen as conservative. Consequently, a number of application scenarios predicted by IMT-2020 are unsuitable for 5G networks.

Introduction to 6G Networks

In addition to the technological restrictions imposed by 5G networks in covering the entire IMT-2020 vision, future mobile networks are getting new applications proposed for them.

For instance, it was evident during the COVID-19 pandemic that stereo sound and bi-dimensional video were insufficient to deliver emotionally consoling messaging.

Applications other than personal communication will profit from the anticipated high data rate and reduced latency provided by 6G networks.

The future infrastructure's low latency can be used to operate remote equipment, and its instantaneous feedback feature enables precise operation. These are the main facilitators for many other uses, such as remote driving and remote surgery.

The Concept of ‘Multisensory Holograghic Communication’

Multisensory holographic communication with haptic data is seen as the next big thing in advanced remote communication. To provide a good quality of experience (QoE), this type of communication needs a high data rate and a fast network response.

The International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) states that holographic and multi-sense media are predicted to play a significant role in future remote encounters.

The four developing situations that ITU-T highlighted are

● Holographic-Type Communications (HTC)

● Multi-sense networks (MSN)

● Time-engineered applications (TEA)

● Critical infrastructure (CrI)

Future Network Requirements and Challenges

To accommodate all future services and applications, 6G networks will require enhanced features in addition to improved communication capabilities. For the upcoming generation of mobile networks, mapping, sensing, and imaging will be equally important as communications.

It has been suggested that using frequencies in the sub-THz and THz bands can boost data rates while giving the network access to sensing, imaging, and mapping capabilities.

The very short wavelengths in these high-frequency bands let the signal interact with the materials at the molecular level. This means that the RF front end can be used as a spectroscopic imaging system. However, when such high frequencies are used, they create a number of problems that need extra attention when it comes to channel modeling and channel reduction.

Multi-Radio Access Network Strategy for 6G

Additionally, 6G networks must accommodate a multiplicity of scenarios, applications, and services. It is obvious that a multi-radio access network (RAN) strategy will be required for the future network to handle all demands. Fig. 1 shows the primary applications, enablers, and needs that are anticipated, and arranged based on the required cell size.

Fig. 1 Main use cases, enablers, and requirements for the 6G networks. Source: IEEE Access

Key Technologies Driving 6G Innovation

In this vision of the 6G network, small cells will offer the connection and functionality needed to serve applications that demand

● Very high data rates (up to 1 Tbit/s)

● Very small latencies (below 0.1 ms)

● Extremely precise positioning

● Map resolutions (below 1 cm)

The three main technologies to meet these needs are

● Ultra-massive multiple-input, multiple-output (umMIMO)

● Visible light communication

● THz communications

Enhancing Network Performance with Advanced Communication Technologies

A few other available technologies to achieve the requirements of 6G networks are listed below

● The difficulties found within the macrocells continue to be astounding. With coverage extending up to 5 km from the base station (BS), THz communications become extremely challenging.

● Signals operating at millimeter wave frequencies are more likely to achieve data speeds of up to 100 GB/s with latencies under 1 ms and precision of up to 10 cm

● Intelligent reflecting surfaces (IRS) and smart beamforming supported by artificial intelligence (AI)-based antennas will be very important for reliable communication over a doubly-dispersive channel

● Light detection and ranging (LiDAR) can also help 6G networks get better at mapping and locating devices.

Addressing Coverage Challenges in Rural Areas

The supercell is anticipated to play a key role in future mobile systems by offering dependable connectivity in rural and isolated areas - a function that hasn't been adequately fulfilled by any network yet.

In this instance, to provide digital services for farms, mines, aircraft, ships, trains, and automobiles, long-range links up to 50 km are required. For remote controlling and video and data collection, even in remote places, data rates of up to 1 Gbit/s and latencies of less than 10 ms are required; autonomous machinery operating in mines and farms requires precision of up to 0.1 m.

● In this scenario, multiple-input multiple-output (MIMO) for diversity can improve the signal strength to expand the coverage range and feasibility, and radio over fiber (RoF) can be employed to lower deployment costs in remote places.

● TV white space (TVWS) can also significantly save on operating costs. Since licenses are not needed to utilize the available ultra-high-frequency (UHF) channels.

Collaboration Between Satellite and Terrestrial Networks

● Lastly, satellite networks and terrestrial networks can work together to enhance coverage or backhaul terrestrial base stations.

Conclusion: Shaping the Future of Mobile Communication

The architecture of the 6G networks includes support for new applications as well as complete fulfillment of the IMT ambitions. It is evident that THz and sub-THz communications, wireless-optical integration, VLC, and new antenna designs are significant players in the definition of the next generation of mobile networks.

The requirements, architecture, and enabling technologies are still being discussed in a number of initiatives and research projects around the world.

Summarizing the Key Points

● 6G networks will revolutionize mobile communication with technologies like ultra-massive MIMO and THz communications, paving the way for unprecedented data rates and ultra-low latencies.

● Integration of visible light communication and intelligent reflecting surfaces will play a crucial role in enhancing network reliability and performance, enabling precise positioning and high-resolution mapping.

● Future mobile networks will require a multi-radio access network strategy to meet diverse demands, including very high data rates, minimal latencies, and precise positioning capabilities.

● The use of artificial intelligence antennas, LiDAR technology, and supercell advancements will be instrumental in achieving reliable connectivity in rural and isolated areas, addressing coverage challenges.

● Collaboration between satellite and terrestrial networks will be essential to extend coverage and backhaul capabilities, ensuring seamless connectivity and support for a wide range of applications in remote locations.