On 15th May, 1951, on the Third Programme, Alan gave his first broadcast, which was one of a series with the general title “Automatic Calculating Machines.” His lecture, the second in the series, bore the sub-title, “Can Digital Computers Think?” I heard at his house its recording, but he stoutly refused to join me, though he plucked up courage to listen to its repetition on 3rd July, 1951. It was, as far as I know, generally agreed that he put his case very clearly. The other participants in the series were: Professor M.H.A. Newman, F.R.S.; Professor F.C. Williams, F.R.S.; and Mr. M.V. Wilkes (later F.R.S.), who gave no sub-title to their lectures. These talks were all reasonably long, not those very short affairs that stop just as one is beginning to get interested.

These lectures were followed on 14th January, 1952, by a fourcornered broadcast discussion on the Third Programme between Professor Sir Geoffrey Jefferson, F.R.S., Professor M.H.A. Newman, F.R.S., Mr. R.B. Braithwaite, Fellow of King's College, Cambridge, and Alan. The subject was, “Can Automatic Calculating Machines be said to Think?” Alan vigorously maintained, with some mild support from Professor Newman, that they could be said to think and bore the brunt of their opponents' objections, particularly those of Sir Geoffrey Jefferson. The general impression of my non-expert friends was that the subject had been presented most amusingly and in such a way as to be, on the whole, within the comprehension of those to whom it was quite new.

On resignation from the Scientific Civil Service Alan accepted a Readership at Manchester University and was appointed Assistant Director of “Madam,” the Manchester Automatic Digital Machine designed mainly by Professor F.C. Williams, F.R.S., and Dr. T. Kilburn. This machine at the time of its construction was reputed to have the largest memory storage capacity of any known machine and was expected to be able to “remember” a bookful of facts and figures.

As Assistant Director (but ignorant himself of the identity of the Director) Alan's role was to collaborate with Professor F.C. Williams and Dr. T. Kilburn and lead the mathematical side of work with the machine. According to Professor M.H.A. Newman's account in the Royal Society's Memoir, “for a few years he continued to work first on the design of the sub-routines out of which the larger programmes for such a machine are built, and then, as this kind of work became standardized, on more general problems of numerical analysis.” With the experience so gained he produced in 1950, The Programmers' Handbook for the Manchester Electronic Computer.

In June 1949, a representative of The Times asked him by telephone sundry questions and put forward certain propositions regarding the scope of the machine; in reply Alan hazarded some forecasts of what the machine might eventually achieve. He was aghast a day or two later to find the results of this telephone conversation expanded into a long paragraph on the centre page of The Times.

We had given up our home in Guildford in March 1939, and being mostly on the move until war broke out we saw little of Alan: during the next six years he could spend only snatches of leave with us, for immediately on the declaration of war he was taken on as a temporary Civil Servant in the Foreign Office, in the Department of Communications.

As a “back-room boy” he was not allowed to enlist, though he served for a time in the Home Guard. At first even his where abouts were kept secret, but later it was divulged that he was working at Bletchley Park, Bletchley. No hint was ever given of the nature of his secret work, nor has it ever been revealed. The enforced silence concerning his work quite ruined him as a correspondent: his letters from then on became infrequent and scrappy. However on his occasional visits to us and on my visits to him I heard of some of the truly Alanesque things that happened during the war years.

His ability was early recognized in his department where he became known as “the Prof.,” or simply “Prof.” He lived at the Crown Inn, Shenley-Brook-End, some three miles out of Bletchley. Here his kind landlady, Mrs. Ramshaw, took great care of him and generally mothered him and admonished him about his clothes. Someone on the staff at Bletchley Park reported to a relative of ours that Alan was “wrapped up in his theories and wild as to hair and clothes and conventions, but a dear fellow.”

This book is a guide to the Weightless technology. The definitive documentation for Weightless is the Weightless standard as published by the Weightless SIG and this book in no way is intended as an alternative. However, standards documents are not designed for readability and it is often helpful to start with a more descriptive text. This book is designed to explain the context for Weightless, the key design decisions and to provide a readable overview to the standard. That may be sufficient for some, and for those that will go on to read the standard they will better understand the details that they find there.

This book was written to accompany version 0.6 of the standard. This is referred to throughout the book simply as the standard. Of course, this standard will evolve and it is envisaged that this book will be updated to accompany major revisions to the standard.

Why the name ‘Weightless’? Like many standards such as Zigbee and Bluetooth, the name chosen is often more whimsy than descriptive. In this case, it came indirectly from making the point that this was not a new generation of cellular standard, measured in generations (2G, 3G …). Indeed, it was outside of this generation pattern and so perhaps zero-G. Zero-G is often associated with no gravity leading to weightlessness … At the time it was conceived most thought that a different name would emerge during the early standardisation process, but as is often the case names acquire a momentum all of their own, even those that have no weight.

The Farringdon Road market was a favourite haunt of Alan's: it was here that he picked up his violin, already mentioned, and here, I think, found the ancient sextant which was to be part of his equipment for his voyage to New York on 23rd September, 1936. He sailed steerage and I saw him off at Southampton. As we did not realize the extent of the docks we walked from the train to the steamer and the sextant was allotted to me to carry. Of all the ungainly things to hold, commend me to an old-fashioned sextant case. Though some readings were taken, what with the movement of the ship, and a defect in the instrument and Alan's inexperience, he doubted their accuracy. He heads his letter from the Berengaria 41° 20′ N 62° W.

A week after arrival at the Graduate College, Princeton, he writes: “The mathematics department here comes fully up to expectations. There is a great number of the most distinguished mathematicians here – J. v. Neumann, Weyl, Courant, Hardy, Einstein, Lefschetz, as well as lots of small fry. Unfortunately there are not nearly so many logic people as last year.” His next letter suggests some disillusionment. “Church had me out to dinner the other night. Considering that the guests were all university people I found the conversation rather disappointing. They seem, from what I can remember of it, to have discussed nothing but the different States they came from. Description of travel and places bores me intensely.”

Morphogenesis is a term used to describe the processes involved in the appearance and development of living structures. How long Alan had been ruminating on his chemical theory of the growth of living things, particularly the mathematical aspect of it, we do not know. Whether in attendance at lectures on physiology in 1947 to 1948 he had this in view, or whether with his wide interests he studied physiology just to enlarge his knowledge and was thereby spurred on to further investigations, it is impossible to say. Whichever way it was, after going to Manchester, he began to develop his noted theory of morphogenesis which naturally led to the study of botany. On his walks and runs he was always on the look-out for flowers and grasses. With some advice from me and the help of British Flora, (much worn after being carried about in his pocket), and Flora of the British Isles, by A.R. Clapham, T.G. Tutin and E.F. Warburg, he identified all those he found in his neighbourhood, and systematically marked on very large scale maps just where he had found the various specimens.

His lengthy monograph on morphogenesis was contributed in November 1951 to the Philosophical Transactions of the Royal Society under the title “The Chemical Basis of Morphogenesis”; this was revised in March 1952 and published by the Royal Society on 14th August, 1952, in the Phil. Trans., Series B, No. 641.

The previous two chapters of the book have focused on the basic issue: perception of the environment from two different viewpoints. Specifically, Chapter 3 focused on perception viewed as power-spectrum estimation, which is applicable to applications such as cognitive radio, where spectrum sensing of the radio environment is of paramount importance. In contrast, Chapter 4 focused on Bayesian filtering for state estimation, which is applicable to another class of applications exemplified by cognitive radar, where estimating the parameters of a target in a radar environment is the issue of interest. Although those two chapters address entirely different topics, they also have a common perspective: they both pertain to the perceptor of a cognitive dynamic system, the basic function of which is to account for perception in the perception–action cycle. In this chapter, we move on to the action part of this cycle, which is naturally the responsibility of the actuator of the cognitive dynamic system.

Just as the Bayesian framework provides the general formalism for the perceptor to perceive the environment by estimating the hidden state of the environment, Bellman's dynamic programming provides the general formalism for the actuator to act in the environment through control or decision-making.

Dynamic programming is a technique that deals with situations where decisions are made in stages (i.e. different time steps), with the outcome of each decision being predictable to some extent before the next decision is made.

My mother has written a biography of my brother Alan. It was certainly a tour de force on her part to write it, as she did, in her seventies. It has rightly been praised, by others better qualified to judge than I am, as a revealing study of a son who became, undoubtedly, a mathematical genius.

I start off, therefore, at a disadvantage. Much of the ground has already been covered, and certainly, so far as Alan's childhood is concerned, far better and in more detail than I could have done it myself. But it is sufficiently obvious to any discerning reader of that book that a false note has been struck somewhere: could Alan have been quite that paragon of virtue that my mother describes? Yet, if an elder brother ventures to suggest the contrary, it can easily be suggested that he is jealous and sour. This is a risk I must accept. My only concern is to put the record straight, however hazardous the enterprise.

My brother Alan was born on 21 June 1912 in a London nursing home. For me, it was a halcyon time, for my father, perforce, had to look after me for the one and only time in his life. His solution of the problem could not have been bettered: we visited the White City, went on roundabouts, ate in restaurants and travelled around the metropolis on the tops of buses with the tickets stuck in our hat-bands.

This quotation is taken from a point-of-view article that appeared in the Proceedings of the Institute of Electrical and Electronics Engineers (Haykin, 2006a). In retrospect, it is perhaps more appropriate to refer to Cognitive Dynamic Systems as an “integrative field” rather than a “discipline.”

By speaking of cognitive dynamic systems as an integrative field, we mean this in the sense that its study integrates many fields that are rooted in neuroscience, cognitive science, computer science, mathematics, physics, and engineering, just to name a few. Clearly, the mixture of fields adopted in the study depends on the application of interest. However, irrespective of the application, the key question is

In this book, we adopt human cognition as the frame of reference. As for applications, the book focuses on cognitive radar and cognitive radio.

Overview

The function of the medium access layer (MAC) is to share the available radio resource among the many thousands of devices that might wish to access it. As discussed in Chapter 4, the starting point in understanding the Weightless MAC is the design options that were selected as a result of the underlying requirements and constraints. Those that concern the MAC include:

• the use of TDD

• long time duration frames

• super-frame structure with sleep mode.

There is never a clean distinction between MAC and PHY and the MAC must provide PHY-level information to the terminals such as the hopping sequence hence there will be some blurring between this and the next chapter.

Scheduled and contended access

There are two ways that a terminal can obtain resource for communications or that the network can communicate with the terminal. These are scheduled access and contended access. Scheduled access occurs when the network and the terminal have pre-arranged to communicate at a particular time. For example, when transmitting a meter reading, the network and terminal may agree the next time that a reading will be sent and this resource is reserved in advance. Contended access occurs when there is information to send that was not envisaged. For a terminal, contended access requires attempting to gain radio resource to signal a desire to communicate. For the network it requires the base station controller making space within a downlink frame to carry the traffic.

On release from his duties at the Foreign Office Alan was offered a Cambridge University lectureship, which he declined since his attention was becoming focussed on computing machinery. Before the war he had already begun to build a computer of his own with wider scope, he hoped, than those then in operation. It was natural, therefore, that his aim should be to see his logical theory of a universal machine, previously set out in his paper “Computable Numbers” (published in 1937), take concrete form in an actual machine. On submission to the Government of the outline of his design for such a machine he was taken on to the staff of the National Physical Laboratory at Teddington, and became a permanent member of the Scientific Civil Service in October, 1945. When this service was reconstructed at the end of the war, senior posts were made available for people of exceptional merit so that “they would be able to advance fairly high in the scientific hierarchy without the usual requirement of undertaking considerable organizational responsibility.” Under this scheme Alan was one of the first to become a Senior Principal Scientific Officer. In the Mathematics Division of the National Physical Laboratory his task was to plan more fully the logical design of an automatic computing engine. According to The Times of 16th June, 1954, “he threw himself into the work with enthusiasm, thoroughly enjoying the alternation of abstract questions of design with practical engineering.”

The World of Mathematics, referred to in Part I, contains an article entitled “The General and Logical Theory of Automata” by John von Neumann which gives the ensuing synopsis (vol. 4, pp. 2093–2095) of Alan's Theory of Computing Automata:

The English logician, Turing, about twelve years ago attacked the following problem. He wanted to give a general definition of what is meant by a computing automaton. The formal definition came out as follows:

Being a scholar born, Alan found himself thoroughly in his element when he went up to King's as a mathematical scholar in October 1931. The balance of freedom and discipline just suited him. He at once took up rowing, being in the College trial eights in 1931, 1933 and 1934. For one so shy it was a curious thing that he very much enjoyed reading the lessons in King's College Chapel, which as a scholar he was occasionally called upon to do. He was too reticent about his religious beliefs to reveal just where he stood. He often accompanied me to church at festivals, as well as attending chapel at King's – things he was too honest to do had he not been, at least, in limited agreement with Christianity, though he was certainly not orthodox. “Within the framework of his science he believed in the great order of things,” according to a very intimate friend. In his last year or so, happening to glance through the Church of England Catechism, by then forgotten by him, he expressed great admiration for the sound exposition of the “Duty to one's Neighbour.” Whenever he referred to Jesus Christ he always did so with reverence using the term “Our Lord,” which speaks for itself. While still at school his opinion of daily school chapel was that the practice was a good one, even if one were apt to be in a state of semi-coma. This may sound paradoxical, but what he commended was evidently the corporate recognition of religious obligation.