Written in my Singapore hotel room and despatched to TechRepublic at 60Mbps over a wired LAN.
Digital signal processing has changed everything in our lives – from the cars we drive, the products we manufacture, and the way we communicate and calculate.
It has also given us the internet and mobile technology. Yet that wireless technology is still based on designs that evolved between 1915 and the 1970s.
A continual process of refinement and miniaturisation – technology polishing, if you will – got us to where we are today, with the added innovation of digital processing technology. But now we find ourselves at a watershed where new techniques are required for any really significant gains.
The use of bands – splitting up the spectrum into convenient chunks for radio, TV, citizens’ use, police, cell phones and so on – could now be replaced by everyone using the same frequencies at the same time.
The interference problems that we would have suffered with analogue technology can now be overcome by digital coding and processing.
A physical analogy would be our ability to talk over the noise of a crowded cocktail party and yet hear nothing at all of the other conversations going on around us.
How is this facility possible for wireless systems? It is a bit of a challenge to explain, but here goes.
Figure 1 shows the analogue banding that separates the energy of one signal from another.
Figure 2 shows those bands removed and all the signals overlapping.
So how are they separated? They are separated by time and angle.
Why is this important? Looking to the future, we can expect an internet of mobile things far in excess of the mobile devices that humans own. These things will be fixed and mobile, long- and short-lived, and they will need to communicate with each other and networks.
The wireless technology of today will not do the job. We will need every ounce of bandwidth and every degree of signal separation we can muster. Removing bands, and spreading signals over a greater span will provide that facility.
If we had no radio systems at all and were starting with a clean sheet of paper, all these issues would pose no problem. But we don’t.
Legacy technology and investment
We have a huge investment and deployment of legacy technology and replacing the old with the new will take some considerable time.
However, there is some good news. The internet of things will mostly involve short-range communication at low power. The spectrum available for that type of communication is well above that used commercially today. It also offers more than 1,000 times the capacity.
Another perspective is the transition from a kW world with thousands of huge masts and big transmitter powers serving millions of radios and TVs, to thousands of mobile base stations at more modest powers measured in watts with millions of users, and then on to billions of mobile devices and things with billions of base stations at very low powers measured in mW and uW, operating over very short distances in continual and sporadic modes.
What happens after that? A migration of the spreading technology, one service band at a time, until the entire spectrum is covered. How long will the process take? Looking at the recent move from analogue to digital TV it could be as long as 20 years and as few as 10 or less once it starts.
After that we have nowhere to go. We have come to the end of the evolutionary road for wireless systems. Of course, added intelligence will be complemented by smart antennas and more processing power, but the basic technology cycle will be sealed.
The radio spectrum, in total, spreads over some 300GHz, but we have only used around 30GHz so far. Then, of course, there is free space optics, which is millions of times greater.
As we extend into the space above 30GHz, there is some really good news. Atmospheric absorption accelerates and communication over more than a few metres or hundreds of metres rapidly becomes impossible and the mutual interference problem dies away quickly.
This is ideal for the future we are building with billions of wireless devices, and we are working symbiotically with nature rather than trying to go in the opposite direction.
What does it all mean for you and me? Improvements in our lives and living, invisible and visible. How big a change?
I reckon it will be about the same size as the move we experienced from those first transistor radios to the internet – or perhaps even bigger.