6G is needed to complete 5G

6G is needed to complete 5G


In November 2015 the European mobile research community were in despair. The European national regulators had failed to support their demand for  a global spectrum allocation at 28 GHz for 5G in the 2015 Word Radio Conference.  There was not even a regional solution to hand. A joke swept around the industry that “even” number of cellular generations were successful but “odd” numbers were not. The joke got its edge from the fact that generation 2 (GSM) was considerably more successful than generation 1 (analogue) and generation 4 is proving far more successful than generation 3 turned out to be. Coincidence? Or is there a reason why mobile generation changes appear to come in pairs?  It is a theory worth exploring as it may tell us something important about 6G.

The Relationship between 1G and 2G (GSM)

The first thing to establish is that, whilst GSM was an outstanding success, its analogue predecessor was certainly not a failed technology.

Analogue 1st Generation

Analogue 1st generation technologies were successful launch platforms for national cellular mobile services in many countries and provided a good solution to the main problem everyone set out to solve – a shortage of radio channels. Its defining technology advance was seamless  “cellular” frequency re-use. The analogue technology networks provided a very good quality mobile telephone service.

1G slide

Figure 1 – Analogue cellular mobile systems successfully relieved car phone channel congestion

The defining shortcoming – The main weakness  of the first-generation analogue technologies was the abject failure to find a harmonised technical standard even across Europe let alone the world. The fragmentation of technologies led to sub-optimal scale economies, high equipment prices and severely limited international roaming. This failure of standardisation was not down to a lack of foresight. National and industry politics just got in the way.

The principle blind spot – Less evident to those defining these first-generation technology standards was the coming consumer mass market of personal mobile phones around the corner. The car phone was the pre-dominant means to make and receive telephone calls. In 1986 85% of customers were demanding car phones.

Digital 2nd t Generation (GSM)

The problem all those involved with GSM were setting out to solve, when the GSM group was formed in 1982, was to find a common technical standard that would be adopted right across Europe. It was not a done deal that GSM would be “digital” until 1986 and that was to leap over the politics of who would win or lose if the standard were to have been analogue.  The major attributes of GSM were defined by the imperative that unless it was better than the prevailing 1st generation analogue technologies it would never get off the ground in the UK, Nordic and other markets where analogue services were becoming very successful.

2G slide

Figure 2 – GSM’s success was redressing the shortcomings of 1G

The defining shortcoming – GSM had no serious shortcomings largely because  the strategic planners had full visibility of the two main weaknesses of the analogue 1st generation technologies:

  • Huge scale economies were guaranteed through the GSM Memorandum of Understanding getting all of Europe’s mobile operators to leap together and introduce GSM by a common launch date
  • The mobile personal phone was put at the very centre of GSM’s design

The principle blind spot – The World Wide Web had not been invented when GSM was defined and video coding not advanced enough to even dream about “video”. These possibilities were never in the GSM scrip. It set the scene that the next generation was going to have to be a revolution that took the industry beyond the mobile “telephone”..

The Relationship between 3G and 4G

3rd Generation

3G’s defining goal was “multimedia” that could be transported on a 2 Mb/s data stream. Its definition phase coincided with the emergence of the Internet.

3G slide


Figure 3 – 3G was seen by many as the fusion of the Internet and Mobile Phone

The defining shortcoming – The vendors promised 3G would deliver 2 Mb/s but release 99 only delivered a problematic 384 kb/s. That shortcoming was resolved through an infrastructure re-boot in the form of the introduction of 3G- HSPA. A more enduring shortcoming was the choice of 2.1 GHz to deliver national 3G services. “3G Coverage” became the number one consumer complaint.

The principle blind spot – The explosion of data from the rise of video left 3G networks overwhelmed.    

4th Generation

4G’s defining goal was mobile broadband with the capacity to cope with the explosion of video traffic over mobile networks.

4G slide

Figure 4 – 4G arriving just in time to handle the video over mobile trend

The defining shortcoming- None are evident. 4G is performing extremely well against the goals set for it. Much of this success can be put down to being able to learn from the shortcomings of 3G:

  • The bottlenecks of 3G have been removed, for example being able to operate in a wider radio channel
  • Spectrum for 4G has been found both above and well below the 2,1 GHz band for 3G. The former, at 2.6 GHz, provides the capacity leap and the latter at 800 MHz has delivered huge improvements in coverage reliability.

The principle blind spot – 4G would struggle if IoT devices exploded into the billions. Efficiency falls with too many carriers in carrier aggregation solutions. Latency is relatively high for tactile applications.

Do mobile generations come in pairs?

The above analysis offers a credible case that 1G and 2G (GSM) were part of the same journey that took the mobile “telephone” from the car of the rich few to the personal mobile telephone of the masses. It is also beyond doubt that the multimedia journey was started with 3G but only completed with 4G.

This raises the question of whether, in both cases, completing the respective journeys in one leap was ever feasible? In complex projects there inevitable will be some aspects that go better than others and certainly what is not reasonable to expect is seeing clearly what is coming around the corner over the life of an infrastructure generation. When analogue cellular mobile systems were being designed it needed a car battery or something close to power them. Similarly, for the 3G/4G pairing, it  is not reasonable to have expected the 3G planners to have foreseen the full impact of the iPhone or Netflix. So the theory of “the pairing of mobile generational changes” has a rational basis.

Does this suggest  there will be a natural 5G and 6G pairing?

5G is a far more complex generation to understand than earlier generations. This is due to the multiple goals it set out to pursue. It is also due the way it has been redefined part way through without heralding this departure from the initial expansive vision. There has also been some sensible project management by the global standards body 3G PP to bring out 5G standards in staged releases. It is therefore very early days to be categoric about the shortcomings of 5G and certainly premature to be identifying its blind spots.

That said, one shortcoming can be predicted with confidence – we will not be getting Gb/s user data speeds over entire urban areas for some considerable time and it is beyond the economic reach of 5G to deliver Gb/s data speeds nationally.  There are likely to be other elements coming to light over the next 3-5 years where the expectations set by the expansive early 5G vision look unlikely to be met. This dose of realism is perfectly consistent with 5G being a success. Early indications are that what 5G does, it will do very well but it won’t doing everything the original visionaries set for it.

What does this tell us about 6G?

A new generation of mobile technology and a blank sheet of paper will have 6G visionaries around the world coming up with dreams, with high odds that many will turn out to be “impossible dreams”. Already there is talk of 1 Tb/s data speeds needing spectrum bands at 95 GHz and above. But bands at 28 GHz for 5G  in the USA already appear to be  a disappointment in terms of sufficient coverage to support a credible mobile service. Customers want their mobile connection to always works, no matter where they are. One therefore has to question whether going even higher in the spectrum is not wondering completely off “the mobile” reservation.

There is a more practical place to start with a far higher probability of being fruitful.  That is to assume now that 6G will come to be paired with 5G and complete the 5G journey of networks delivering the pervasive perception of unlimited capacity. Then everything else that comes to be added later to 6G, when the unknown unknowns come to be known, will be the icing on the cake or even the start of the 7G journey.




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