Key Challenges Of 6G Technology

6G seeks several orders of scale upgrades over 5G in all aspects. But certain obstacles exist, where major efforts will be required. Some of them are already being observed and partly addressed in 5G systems.

1. Access networks for backhaul traffic: The recently formed ITU-T Focus Group Technologies for Networks 2030-FG NET-2030 (established by ITU-T Study Group 13 at its meeting in Geneva, 16-27 July 2018) raised concerns that fixed access network capabilities are already lagging behind in emerging 5G systems. It is anticipated that access networks for backhaul traffic will struggle to cope with the unique data growth and other quality requirements unless necessary steps are initiated to boost the research effort.

2. Sub-millimeter Wave and THz spectrum: Preliminary research indicates that frequencies in the THz and above range will be considered for 6G as those bands have suitable free spectrum bands to meet this requirement. A study indicates that the 5G spectrum may not exceed 140 GHz due to several challenges including lack of understanding of channel and propagation modelling, inability of devices to operate at such high frequencies, juxtaposition in frequencies, etc. 6G will use a spectrum beyond 140 GHz with application in very short range communications or ‘whisper radio’. However, the sensitivity of the THz band to blockage, molecular absorption, sampling and circuits for A/D & D/A conversion and communication range are among the major challenges that need to be addressed in the coming years. An additional issue is that at higher frequencies, antenna sizes and associated circuitry become miniaturised and are difficult to fabricate on-chip while ensuring noise and inter-component interference suppression. On the other hand, the exact propagation characteristics of the THz band are not well understood.

3. 6G Standardization: Various study groups are drafting an initial set of standards based on unique use-cases and KPIs. 3GPP is hoping to make 6G requirements public no later than 2023. Thus, fully 6G systems will not mature before 2030. With 6G, we cannot expect to reach a time when testing is complete, which is also true with 5G. The industry will need to continuously validate standards compliance, performance, security, and interoperability as the lifecycle progresses – from the lab to preproduction, as we start rolling out services, and as we scale to a larger number of users. And whenever any variable in the environment changes, we will need to repeat that effort. With 6G and even 5G in that case, we are no longer measuring bytes coming in and out of the network equipment interface. We need to test the interplay of lots of virtualized nodal functions, in many different ways. This includes testing standalone functions, their handoffs to adjacent functions, and their behavior as part of a holistic system that they have replaced. We need to rethink our testing approaches from the ground up.

More than ever, 5G and 6G systems will demand independent, vendor-agnostic testing and verification. And this will require a level of automation that legacy and homegrown testing approaches cannot meet. If you cannot use prebuilt test-cases and run them automatically, you will never get to market. Hence, there is a need to create an entire testing and standardization ecosystem, where we are still lagging behind. Such an ecosystem will be a prerequisite for developing any wireless communication system, be it 5G or 6G.

4. Fog Networking and Mobile Edge Computing: Fog networking and edge computing have been introduced in 5G to greatly reduce the distance of UEs to the serving base stations and service/application content servers respectively. However, edge caching breaks down the network into a distributed cloud structure where training data resides at the network edges, which hinders AI technologies to be fully functional. The network is inevitably going to move towards smaller cells for more capacity and lower latency in 6G, and this situation will escalate.

Conclusion

As 5G is in its final testing phase getting ready for its launch in the rest of the world, discussions have already begun to shape what 6G could be. 6G will require many years to take shape, as we have seen with previous generations in the past. However, there are already high-profile initiatives around the world aiming to develop technologies for 6G, such as the Next G Alliance in the U.S. and Canada; Hexa-X, Rise-6G and New-6G in Europe; Toves for 6G Li-Fi in the UK. While it is too early to define 6G and there are inevitably omissions in any such discussion, with this piece we have taken a brave approach to identify the potential enabling technologies for 6G and describe the features they bring beyond the capability of 5G.

Read Also:

1. 6G Challenges and Enabling Technologies
2. New Perspectives On 6G Use Cases
3. On The Road To 6G
4. Advantages Of 6G Networks
5. Key Aspects And Diverse Use Cases Of 6G
6. A Journey Of Mobile Networks: From 1G To 6G
7. Introduction About 6G Networks
8. Future Research Directions In 6G
9. Overall Challenges In 6G
10. Towards 6G Communication: Architecture