Hailed as the connectivity technology to end all other connectivity technologies, 5G is expected to improve network efficiency and performance empowering new user experiences and connecting new industries. The three key components which underpin the technology - the so-called “5G triangle” - enhanced mobile broadband, massive IoT and ultra-reliable low latency, are expected to usher in new immersive experiences, connect embedded sensors to facilitate machine to machine communications and transform industries by enabling remote control of critical infrastructure. Crucially, 5G’s pièce de resistance is its forward compatibility that will give birth to use cases beyond our current comprehension.
But as deployments begin, the limitations of 5G are starting to be exposed. 5G has made significant moves to a more software defined Core Network and RAN, but its architecture means it may only take us so far when it comes to enabling new user experiences. While 5G will open the door, the industry needs 6G to push use cases, such as connected cars and extended reality, into the mainstream.
5G’s natural limit
As deployments begin and the industry tries to monetize 5G through new use cases, many of the applications envisaged aren’t quite as simple to implement as first thought. Why? Because of the focus placed upon use cases that use multiple points of the 5G triangle, as opposed to use cases that can be enabled by any single point.
Picture the autonomous cars use case, touted as a near-term commercial reality. But in reality, this use case relies on all three components working together – enhanced mobile broadband, massive IoT and ultra-low reliable latency are crucial to its success. It requires a high data rate across a wide coverage area for people to remain connected while driving. The cars will have to communicate with other objects such as traffic lights and other cars, and ultra-reliable low latency is critical in ensuring the car can respond to events on the road in real-time.
To enable connected cars via 5G involves fusing together the components of the triangle using two or more dedicated network slices, which reserve parts of the network for specific performance characteristics. For instance ultra-reliable low latency services require shorter packets, resulting in more overhead, while massive IoT demands efficiency. Fusing these services together creates complex scenarios not fully explored by 5G. When you begin to scale, it is not clear 5G will efficiently support the competing mixes of services.
5G’s limitations stem from the tension created by focusing on technology to support the three separate points of the 5G triangle and peddling use cases which necessarily combine these components. This has contributed to the stunted progress on new use cases beyond the promise of better-quality mobile video for consumers.
Enabling currently imagined 5G use cases involves all three components working symbiotically. And providing the technological glue between the three points creates a compelling case for the next generation of connectivity technology capable of creating hybrid services more flexibly.
When you throw 5G’s bandwidth into the mix, the limitations come into sharper focus. While 5G’s bandwidth will be drastically larger than 4G, it still won’t be enough to enable some of the more transformative use cases such as multimodal extended reality (MXR). Multimodal XR goes a step beyond XR by adding other sensory modalities, such as touch or temperature.
Enter 6G
While consensus on the definition of 6G is yet to be agreed, the need for a connectivity technology that will give rise to truly flexible systems capable of supporting hybrid services necessitates a 6G evolution.
Let’s take MXR again as an example, thought of as the leading contender for the next mobile compute platform with the evolutionary potential of a smartphone. Its mainstream adoption will require connectivity technology to facilitate both augmented and virtual reality as well as synchronization of the experiences together in real time. Today, 360° 4K video needs 10-50Mbps to reach consumers. Yet the next generation 360° 8K needs 50-200Mbps, which already exceeds 5G’s capabilities. Free viewpoint video, critical for fully immersive experiences, requires 200Mbps to 5Gbps. But if 5G can’t support 360° 8K video, it’s clear how visual processing for free viewpoint video, and therefore immersive experiences, will ‘break’ 5G in the future. Add to this the need to share compute and air interface resource with time critical control loops for sensory features, and we have another application where combining components of the 5G triangle is essential.
To get close to ubiquitous Gbps processing capabilities, 6G must explore higher frequencies. But once use cases start pushing 80Ghz or 100Ghz a fundamental problem begins to appear with the digital design of Orthogonal Frequency Division Multiplexing (OFDM) methods. As such, there are already discussions exploring high level spectrum to enable a more hybrid digital/analog type of design and therefore, the transition from 5G to 6G will likely require a new radio design.
2021: the year 6G penetrates mainstream conversation
There’s no doubt that 5G will provide enhanced bandwidth and a reduction in latency for greater network experiences today. 5G will also play a fundamental role in the progression of new use cases and it still has a long and rich roadmap ahead.
But as deployments begin it appears that 5G will only take us part way along the path to realizing use cases such as volumetric media streaming, connected industries, autonomous vehicles and extreme coverage reaching the last billion. 5G is still in its infancy but use cases such as extended reality show how its architecture will be pushed to its breaking point.
2021 will see industry attention turn to 6G, focusing on how this generation will fix the shortcomings of 5G. Similar to the 3G to 4G evolution, 5G will lay the groundwork and 6G will carry the use cases over the line.
