Interest in a new generation of engineering systems enabled with cognition, started with cognitive radio, a term that was coined by Mitola and McGuire (1999). In that article, the idea of cognitive radio was introduced within the software-defined radio (SDR) community. Subsequently, Mitola (2000) elaborated on a so-called “radio knowledge representation language” in his own doctoral dissertation. Furthermore, in a short section entitled “Research issues” at the end of his doctoral dissertation, Mitola went on to say the following:

Then, in Haykin (2005a), the first journal paper on cognitive radio, detailed expositions of signal processing, control, learning and adaptive processes, and game-theoretic ideas that lie at the heart of cognitive radio were presented for the first time. Three fundamental cognitive tasks, embodying the perception–action cycle of cognitive radio, were identified in that 2005 paper:

• radio-scene analysis of the radio environment performed in the receiver;

• transmit-power control and dynamic spectrum management, both performed in the transmitter; and

• global feedback, enabling the transmitter to act and, therefore, control data transmission across the forward wireless (data) channel in light of information about the radio environment fed back to it by the receiver.

The Turing family is of Norman extraction and the family tree goes back to 1316 AD, the family motto being Fortuna audentes Juvat. Having arrived in Scotland the members settled in Angus in a barony of that name, whence they removed to Aberdeenshire early in the fourteenth century and came into possession of Foveran, which remained the family seat until recent times. The name was variously spelled Turyne, Thuring, Turin, Turing. William Turin received the honour of knighthood from James VI of Scotland (James I of England) and thereafter Sir William added the final “g” to the name.

John Turing of Foveran was created a baronet by Charles I in 1639 for loyal service, and was at the battle of Worcester; but his loyalty cost him the loss of lands which had been in the family for 300 years. Records show Turings holding positions of trust and responsibility in the County of Aberdeen.

By the eighteenth century some Turings were venturing further a field. Thus Sir Robert Turing (Bart.), born in 1744, was a doctor and amassed a considerable fortune in the East Indies and then retired to Banff in Scotland where he made himself very useful and popular. One kinsman in the Honourable East India Company took part in the defence of Seringapatam. Others in the nineteenth century lived in Holland; two, father and son, were successive British Consuls in Rotterdam. Some of their descendants have now become domiciled in Holland. Alan's great grandfather, presumably through this Dutch connection, had some occupation in Batavia, maybe in some shipping concern.

This book has introduced the Weightless standard, setting out the need for a wide-area wireless machine communications network and explaining how the advent of white space spectrum has provided the last piece of the puzzle needed to make such a network reality. However, the mix of very particular requirements for machine communications and the need to operate under complex rules and challenging interference within white space has led to the need for a bespoke new technology. Chapters in this book, and the standard, set out in detail the design decisions for Weightless, the specifics of the network, the base stations, the medium access layer and the physical layer. Subsequent chapters demonstrate how Weightless could be deployed in a nationwide network and the coverage, capacity and business case that would result from such a deployment. Finally, we concluded by looking at some of the key applications for Weightless and how they could be served by the standard.

Weightless is a unique technology. It could enable smart energy, smart cities, healthcare solutions to allow people to live at home longer and much more. It can generate excellent returns for those that make and deploy the technology and those that deliver applications using it. And, by providing the enablers to address climate change and the aging population, it might just save the world.

Defining white space

Most of the spectrum below 10GHz across most of the world is allocated for particular applications and assigned to certain users. These include broadcasters, mobile phone network operators, defence departments and many, many more. The net result is that there is little obviously spare spectrum, particularly in the preferred frequency bands between around 300MHz and 3GHz where propagation is favourable but antennas are conveniently small. However, measurements of the actual utilisation of this assigned spectrum suggest that it is typically only used in around 20% of the locations. Such measurements undoubtedly underestimate usage but nevertheless it is clear that there is some potential for more efficient use of the spectrum.

One way to visualise where there might be underused spectrum is to plot on a map the strength of signal from the licensed user of that band. If colours are used to represent signal strength then those parts with no coverage at a given frequency will be uncoloured and appear white on a black and white map. Hence the term ‘white space’ for areas where there is potential for others to use the spectrum.

This book contains almost all the essential material for the biography of a very remarkable man, who died tragically in June, 1954, in the prime of his life and in the middle of research which may still prove to be even more original and important than the finished work which had brought him so much honour and fame. Alan Turing's mother, who has assembled and written this record of his childhood and his mature achievements, believes that his death was accidental. The explanation of suicide will never satisfy those who were in close touch with Alan during the last months and days of his life, however much the available evidence may point to it, and in the future the possibility of accident will be considered by those in a better position perhaps to decide the truth. But even if his death was not chosen by him, he was a very strange man, one who never fitted in anywhere quite successfully. His scattered efforts to appear at home in the upper middle class circles into which he was born stand out as particularly unsuccessful. He did adopt a few conventions, apparently at random, but he discarded the majority of their ways and ideas without hesitation or apology. Unfortunately the ways of the academic world which might have proved his refuge, puzzled and bored him; and in return that world sometimes accepted him wholeheartedly (I remember ShaunWylie's saying “He was a lovely man: never a dull moment”) but often felt puzzled by his remoteness.

Alan's house had a room from which the bathroom had been sliced, leaving a space – the “nightmare room” as he called it – useless for domestic purposes. This he eventually turned into a laboratory where he spent many happy hours carrying out experiments. According to some of his friends these were often of an unnerving character. On one occasion Dr. Gandy refused to take part in one such experiment in a laboratory alive with electrical equipment, though he was prepared to pursue it in the kitchen. It only goes to show Alan's readiness to take chances when possessed by some absorbing idea. One who knew him well wrote to me that he was like a child when experimenting, not only taking in the observed result mentally but testing it with his fingers. He adds: “When we worked together on some electrical contraption he several times got high-voltage shocks by sheer carelessness.” One experiment that he carried out to his own great satisfaction was the gold-plating of the bowl of an egg-spoon: he used his grandfather's gold turnip-watch for the gold and, presumably, potassium cyanide, hence the presence of the latter in solid form in a drawer in his spare room.

Dr. Robin Gandy has given a full account of their joint activities over the week-end a few days before Alan's death. They were busy with the preparation of a non-poisonous weed-killer and sink-cleaner. “There was nothing sinister about these experiments, which were just an example of Alan's liking to make things himself.”

Machine communications does not yet have the necessary standard

The observation, noted in the last chapter, that there was massive potential in machine communications is not a new one. Over the last few decades many have noted that the installation of a wireless connection into myriad devices would bring a range of benefits. However, the market for machine communications to-date has been weak. There are some cars with embedded cellular modems and some relatively high-value items such as vending machines are equipped with cellular packet-data modems. But the market today is only a tiny fraction of the size it has long been predicted to grow to. This is predominantly due to the lack of a ubiquitous wireless standard that meets the needs of the vast majority of the machine market as set out in Chapter 1. There is no current wireless system that comes close to meeting all of these requirements.

Cellular technologies do provide sufficiently good coverage for some applications but the hardware costs can be $20 or more depending on the generation of cellular used and the subscription costs are often closer to $10 per month than $10 per year. Battery life cannot be extended much beyond a few months. Cellular networks are often ill-suited to the short message sizes in machine communications resulting in massive overheads associated with signalling in order to move terminals from passive to active states, report on status and more. So while cellular can capture a small percentage of the market which can tolerate the high costs and where devices have external power, it will not be able to meet the requirements of the 50 billion device market. Indeed, if it could, it would have done so already and there would be no further debate about the need for new standards.

Perception of the environment, viewed as a problem in spectrum estimation as discussed in Chapter 3, is most appropriate for applications where spectrum sensing of the environment is crucial to the application at hand; cognitive radio is one such important application. A distinctive aspect of spectrum estimation is the fact that it works directly on environmental measurements (i.e. observables). However, in many other environments encountered in the study of cognitive dynamic systems, perception of the environment boils down to state estimation, which is the focus of attention in this chapter.

We defer a formal definition of the state to Section 4.4, where the issue of state estimation is taken up. For now, it suffices to say that estimating the state of a physical environment is compounded by two practical issues:

1. (1) The state of the environment is hidden from the observer, with information about the state being available only indirectly through dependence of the observables (measurements) on the state.

2. (2) Evolution of the state across time and measurements on the environment are both corrupted by the unavoidable presence of physical uncertainties in the environment.

To tackle perception problems of the kind just described, the first step is to formulate a probabilistic model that accounts for the underlying physics of the environment. Logically, the model consists of a pair of equations:

• a system equation, which accounts for evolution of the environmental state across time, and

• a measurement equation, which describes dependence of the measurements on the state.

Sara Turing, a woman in her seventies mourning the death of Alan, her younger son, a man that she failed to understand on so many levels, wrote this remarkable biographical essay. She carefully pieced together his school reports, copies of his publications, and comments on his achievements by experts. But Alan Turing was a thoroughly unconventional man, whose method of dealing with life's situations was to think everything through from first principles, ignoring social expectations. And she was trying to fit him into a framework that reveals more about her and her social situation than it does about him. Alan's older brother John trying to fill in the gaps he saw in his mother's account, also ends up revealing a good deal about his own attitudes.In these few pages I will discuss some of the questions that may occur to readers of these documents.

Alan Turing's War

In 1940, after France had been defeated, Britain fought on mainly alone. The merchant shipping on which the island was dependent was being sunk by German submarines at a rate that threatened to force the UK to yield. The radio communications between the submarines and their base concerning their operational plans were being picked up in Britain. If these plans were known, attacks could be mounted against the submarines. Merchant ships could adjust their routes so as not to go where they would encounter enemy submarines. But of course the data was encrypted.

Alan was broad, strongly built and tall, with a square, determined jaw and unruly brown hair. His deep-set, clear blue eyes were his most remarkable feature. The short, slightly retroussé nose and humorous lines of his mouth gave him a youthful – sometimes a childlike – appearance. So much so that in his late thirties he was still at times mistaken for an undergraduate; hence occasional attempts were made to “prog” him.

In dress and habits he tended to be slovenly. His hair was usually too long, with an overhanging lock which he would toss back with a jerk of his head. The first thing to be done when he came home was to send him to have his hair cut. When he did take the trouble to comb it, five minutes later he would run his fingers through it so that once more it would be standing on end. At King's, for a time he took more trouble with his clothes and even subdued his hair. But when the war came he was seldom at home, clothing and sartorial advice were both rationed, and he relapsed into the old ways. In his last years there was again some slight improvement and he used to object to complaints about his clothes. The real trouble, perhaps, was not so much the clothes that he wore as the way in which he wore them.

The General Strike of 1926 broke out as Alan's first term started. He dearly loved a bit of adventure and so was delighted with the opportunity the strike gave of a novel mode of arrival at school – a new school at that. Landing at mid-day at Southampton from France, he sent a telegram to his housemaster, Mr. Geoffrey O'Hanlon, promising to report next day. Then he disposed of his trunk, and set out armed with a map to bicycle to the school. When he hopefully suggested the possibility of bicycling, I insisted that he should not attempt the whole sixty miles in one day, thinking he might be ruthlessly made to attend early school next day. He spent the night at Blandford at the Crown Hotel, where he seems to have caused some diversion, for the whole staff turned out next morning to see him on his way. His bill for dinner, bed and breakfast was purely nominal – six shillings. This unusual way of arrival won him some notoriety and was even reported in the local press. His enterprise stood him in good stead a year or two later; when progress was at a low ebb his housemaster, seeking some redeeming feature remarked: “Well, after all he did bicycle here.”

Alan's first letter from Westcott House, Sherborne, informs us that “Mr. O'Hanlon is very nice” and indeed he proved to be the perfect housemaster, towhomwe owe anundying debt of gratitude.

Introduction

It would be possible to write a book about Weightless without much discussionabout the network. This is partly because the network is not included within thespecification and partly because the network is relatively simple.

The Weightless specification covers the interface from the base station into thenetwork. However, unlike cellular networks there are no defined interfaceswithin the network. This is because it is envisaged that all the networkfunctions can be run on a virtual machine within the cloud. The interface fromthis machine to the base stations is well defined. The interface from thismachine to the client networks will likely be bespoke for each client networkand therefore not appropriate for specification. Hence, there are no furtherinterfaces to standardise.

It might seem rather incredible that the core network of a cellular systemconsisting of many large and expensive computing platforms can be collapsed intoa single virtual machine within Weightless when a machine network is likely tohave many more subscribers than a cellular network and further much of theintelligence typically found in a base station in a cellular network has beentransferred to the core.