5G Limitations and Radical 6G Innovations


Dr Peter Cochrane recently wrote an article that he shared on Twitter. In an article titled, 'Where is Wireless Going?', he says:

Arguably, the biggest changes in wireless technology over the past 120 years occurred with cellular networks and the transition from analogue to digital. Cellular operation was a radical step in itself but moving to digital was transformative of societies. So, the 2, 3, 4 and 5G progression has been entirely predictable with more of the same, but smaller, faster, and greater computing power and more bandwidth in a roughly seven-year innovation cycle. Today, 5G is in the roll-out phase and creative minds across the planet are now focussed of 6G and what happens next. For sure we are due another radical sideways leap in the technology, its uses and operations. Much of this is axiomatic, but most is not. 

People and machines: Mobile has been dominated by people and their needs with lip service being paid to the rising demand for Machine-to-Machine (M2M) and Internet of Things (1oT) systems necessary for Industry 4.0. 6G will reverse this polarisation as 5G thinking cannot possibly satisfy future demands. 

Infrastructure: Most of the claims made for 5G will never be realised without extensive investments in optical fibre to cell sites, more fibre-fed microcells in homes, offices and factories. 6G looks set to break with this cell-model and be the first large-scale rollout of mesh-net operations with massive variable latencies. 

Energy limitations: 5G is the most energy-hungry/wasteful mobile technology ever and probably at the limit of what the planet and society can afford. With some towers / cell-installations consuming over 10kW, the notion that we might serve billions of nodes for M2M and the loT is clearly untenable! 6G has to address this as it may have to support over 250Bn devices and things communicating over very short distances in clusters that are fixed and mobile. 

The bandwidth crisis: This is an artificial manifestation of a management fail where the limited thinking of the bands and channels model sees allocations equated to occupancy. In reality, the broadcast bands operate at about 20% occupancy, whilst the spectrum from 3GHz to 300GHz is currently seeing an occupancy of less 1%. For 6G to satisfy a machine-dominated world, it would ideally occupy frequencies above 100GHz and use μW instead of mW. 

Radical 6G innovations: At 100GHz and above, antennas are small enough to be on-chip with phased arrays and beam steering made more efficient and practical. Of course, the transmit power available progressively reduces as we progress up the spectrum, but this is offset by improving receiver sensitivity. On another dimension, Industry 4.0/5.0 will see increasingly smart materials and surfaces. This may promoter scatter, reflection, and active surface collaboration for 6G and path/channel optimisation. 

Ultra wideband: The wireless development population at large are almost entirely imbibed with the notion that bandwidth is expensive and should be conserved, and therefore systems will just naturally become more and more complex due to the need for more coding and signal processing. But it doesn't have to be this way! Bands and channels are a manifestation of the analogue era and they are in many ways an unnecessary limitation. Signal spreading with code division multiplex in the form of ultra wideband or even hyper wideband implies the abandonment of bit/s/Hz optimisation and the adoption of Hz/bit/s extravagance. This is an ideal mode for the loT and some M2M cases. But it may be a bridge too far, and we might have to wait for 7 or 8G for this to be adopted! 

And the rest: WiFi hotspots currently outnumber mobile cell sites by >380M and, when offices and homes are included, this number exceeds 2Bn. Not surprising, WiFi dominates as an internet connector! And then there is BlueTooth, ZigBe and a host of new standards being developed; it should not be assumed that the 'G' technologies will dominate! 

The way in which all this will pan out is impossible to say but, logically, a time will come for a radical condensation of the numbers of systems on the basis of the economies of scale and our efforts to realise sustainable societies. For my part, I recommend watching the developments in materials science, smart surfaces, and the embedding of smarts in everything we make, use and consume. 

One of the 5G Architecture we think that is mostly overlooked right now is what is known as Wireless Wireline Convergence or WWC. The 5G System has been enhanced to work with trusted and untrusted Wi-Fi as well as wireline networks. This will drive seamless coverage of 5G and 6G indoors. There may not be much point bringing cellular connectivity indoors. All depends on how quickly operators realise the potential that lies in it.

Further Reading: