Nº 3 2015 > ITU Radiocommunication Bureau

Evolving Radiocommunications

By Fabio Leite
Former Deputy-Director of the ITU Radiocommunication Bureau

“The electric telegraph is the most perfect invention of [current] times — anything more perfect than this is scarcely conceivable, and we really begiThe first post-World War One ITU radiotelegraph conference was held in Washington D.C. in 1927Evolving Radiocommunications
“The electric telegraph is the most perfect invention of [current] times — anything more perfect than this is scarcely conceivable, and we really begin to wonder what will be left for the next generation, upon which to expend the restless energies of the human mind.” Melbourne Argus newspaper, Australia, 1853
The first post-World War One ITU radiotelegraph conference was held in Washington D.C. in 1927

Inventiveness

ITU was in the process of being founded, following the invention of the electrical telegraph, when James Maxwell formulated what has been called the ’second great unification in physics’ (after the first realized by Isaac Newton): the classical theory of electromagnetic radiation. The world waited another twenty years for Heinrich Hertz to conduct his laboratory experiments in Germany conclusively demonstrating the existence of the electromagnetic waves predicted by Maxwell.

The start of the 20th Century saw inventors, scientists and entrepreneurs using electromagnetism to create radio devices driving the first wireless telegraph transmissions, broadcasting, and transatlantic communications. Various developments in radio technology flourished almost simultaneously in different parts of the world: Hertz-Henry’s damped wave spark-generated transmission systems; Popov’s coherer; Tesla’s tuned transformer circuits; Marconi’s one-way wireless spark-generated transatlantic communications; Fessenden’s heterodyne principle; and Armstrong’s superheterodyne receiver (which remains the standard radio-receiving method until today).

Regulating early radio

The early 1900s saw the first major use of radio to provide a widespread communication service for ships at sea, which had proved impossible with traditional electrical telegraphy. As more and more ships became equipped with radio, however, problems soon arose. The lack of any kind of international regulation meant that operators could do more or less as they pleased. Interference became an acute problem, and the efficiency of communications was greatly reduced.

This situation led to the first International Radiotelegraph Conference in 1906 in Berlin, where the first International Radiotelegraph Convention was signed. The Annex to that Convention contained the first regulations governing wireless telegraphy. These regulations, which have since been expanded and revised by numerous radio conferences, are now known as the Radio Regulations, maintained by ITU.

The rapid development of maritime radiocommunications, including the need to enable equipment of different manufacturers to interoperate, and the aftermath of the Titanic disaster, encouraged governments to adopt a new set of international regulations at a subsequent Conference in London in 1912, which included the obligation to install radio aboard ships and to set up a continuous radio watch.

The first post-World War One ITU radiotelegraph conference was held in Washington D.C. in 1927. This conference marked a turning point in the technical provisions of the Radio Regulations, as it then became necessary to restrict the use of some of the older types of emitters, the spark-type sets (although relatively cheap, these transmitter sets occupied a broad frequency band) and to divide up the radio spectrum more efficiently among a rapidly growing number of services. Governments agreed on some fundamental principles for the ITU regulations to successfully ensure growth in radiocommunications: procedures for vesting rights to use of specific radio channels “free from interference” from stations of other nations, and the importance of participation of private companies in the ITU. It is also fair to say that the notion of the economic value of the spectrum started to emerge around this time.

Broadcasting

On 24 December 1906, Professor Fessenden presented the world’s first radio broadcast transmission consisting of a speech by himself as well as some selected music for Christmas. However, it was only from the 1920s that broadcasting began its widespread growth, following the discovery of the long-distance propagation proprieties of short-waves (high frequency or HF) and the developments of radio technology resulting from the First World War (e.g. the spectrum-efficient vacuum tube transmitter).

Amplitude Modulation (AM) was the earliest modulation method used to transmit voice by radio. It was developed during the first two decades of the 1900s starting with Fessenden’s radiotelephone experiments. Wartime research greatly advanced the art of AM modulation, and after the First World War, the availability of cheap tubes sparked a significant increase in the number of radio stations experimenting with AM transmission of news or music. The vacuum tube was responsible for the rise of AM radio broadcasting around 1920, the first electronic mass entertainment medium.

Already by 1925, there were over 500 broadcasting stations in operation in the United States, while almost every European country hosted a regular broadcasting service. AM remains in use today in many forms of communication and broadcasting: for example, portable two-way radios, VHF aircraft radio and medium-wave AM radio broadcasting. AM remained virtually the only type used for radio broadcasting until frequency modulation (FM) broadcasting began after World War Two. Digitalization substantively improved both video and audio broadcasting, allowing high-fidelity CD-quality audio and high-definition video transmission, as well as a range of interactive services for users.

During the 1950s, the need to operate broadcasting services on a more planned basis became evident for the sake of efficiency and equity. Consequently, plans were established in the ITU Radio Regulations and Regional Agreements applicable to terrestrial broadcasting in different frequency bands (low frequency (LF), medium frequency (MF), very high frequency (VHF)/ultra high frequency (UHF)) at the start of the 1960s. HF broadcasting remained a very contentious issue, to the extent that the arrangements adopted for this service require little more from the nations than trying to coordinate a broadcasting schedule among themselves, with the administrative assistance of ITU. In general, however, actions taken in the framework of ITU, particularly the establishment of plans, notably helped stimulate the orderly development of broadcasting across all ranges of the radio spectrum.

Fixed communications

Microwave relay links were first tried in the 1940s, intended mainly for point-to-point communications using short wavelengths, which allows conveniently sized antennas to direct the radio waves in narrow beams. They experienced significant growth in the 1950s when ITU, having already allocated spectrum in different bands for fixed service, promptly adopted frequency channel arrangements to allow the systematic use of microwave radio-relay links in different parts of the world. Today, the fixed service continues to be used extensively to provide different applications for local and long-distance communications to the public, in the control of gas pipelines and electric powerline networks, and for coordinating local government activities. Another common application is for services ancillary to broadcasting, used by broadcasters to distribute programmes within a broadcaster’s operations, e.g. to transfer a TV programme between the studio and a mountain-top transmitter site.

Radio and regulations in space

Following the first experimental launches of artificial satellites in the 1950s, the first active communications satellites appeared in the 1960s. During the subsequent decade, advances in satellite performance came thick and fast, and a global industry began to develop rapidly. At first, satellites were used mainly for international and long-haul telephone traffic and the distribution of television, both internationally and domestically.

The first general revision of the Radio Regulations was made by the ITU radio conference, in Geneva in 1959, which took account of the advances in radio technology to extend the ITU Table of Frequency Allocations up to 40 GHz and to define a new satellite radiocommunication service. In order to meet the challenges of new space communications systems, the ITU also set up a Study Group responsible for studying space radiocommunication in 1959. In addition, an extraordinary conference for space communications was held in 1963 in Geneva to allocate frequencies to the various space services. Subsequent conferences made further allocations and put in place regulations governing the use, by satellites, of the radio-frequency spectrum and associated orbital slots.

Despite its high upfront investments and risky nature, the satellite industry continues to expand rapidly — today, its total annual revenue has been estimated at above USD 190 billion from satellite services, manufacturing and launches. The satellite international regulatory framework established by ITU has proved responsive to the needs of industry, technological evolution and growth in traffic. ITU will continue to provide regulatory certainty, orbit and spectrum resource allocation and assistance to all players in the satellite industry.

The mobile revolution

Although the concept of low-power transmission in hexagonal cells was introduced in the late 1950s, electronics only became sufficiently advanced to achieve this one decade later. However, there was still no method for handover from one cell to the next. That problem was solved with the first functioning cell system and first cellular phone calls in the early 1970s, using a phone developed by Martin Cooper of Motorola in the United States, which weighed about 3 kilograms. In the late 1970s, cellular phone services began in Japan and the Nordic Mobile Telephone (NMT) system was deployed in Norway, Sweden, Finland, and Denmark and in 1983 in the United States. These systems represent first-generation (1G) analogue cellular telephony.

The second generation (2G) of mobile communications was introduced in the early 1990s and was characterized by digital technology and the introduction of texting. Digital mobile cellular systems provided for a rapid expansion of the service by allowing for good-quality voice, texting, and personalization. The Global System for Mobile communications (GSM) became a successful standard in Europe and later in the rest of the world, where other digital systems were also in use, such as the Personal Digital Cellular system (PDC) in Japan and Personal Communication Service (PCS) in North America.

At that moment, ITU membership decided to create a group of experts to work on a high-capacity global mobile communication system — the International Mobile Telecommunication (IMT) system, to establish the basis for 3G. The first designation of global spectrum was made in 1992 in the 2 GHz band and an agreed family of standards was established in 2000, based on packet switching for data transmission. Today, according to ITU’s latest estimates, 3G accounts for over a third of the around 7 billion mobile-cellular subscriptions in the world. ITU continues to guide governments, regulators and industry towards the expansion of the mobile service landscape through its work providing for spectrum identification, frequency channel arrangements, numbering resources and free-circulation of terminals for existing and future generation systems.

Regulating modern wireless systems

The 1980s and 1990s saw extensive changes to the Radio Regulations as the output of the ITU World Radiocommunication Conferences. Frequency allocations were identified for emerging wireless applications, mainly in the field of space communications, broadband non-geostationary satellite systems, and plans for broadcasting and fixed-satellite services. Spectrum has also been identified for advanced mobile communications for the use of IMT‑2000, the ITU-developed third-generation global standard.

The 2002 ITU Plenipotentiary Conference held in Marrakesh, Morocco, took the landmark decision that “world radiocommunication conferences can include in agendas for future conferences, items relevant to spectrum regulation of frequencies above 3000 GHz and take any appropriate measures, including revision of the relevant parts of the Radio Regulations”. This was a significant milestone in the regulatory history of radiocommunications, as it paved the way for the exploration of optical free-space telecommunications within the framework of radiocommunications.

Evolving radio technologies

The development of radiocommunications has seen constant technological breakthroughs throughout its history. I shall briefly mention some of the inventions which have leveraged all kinds of radio applications to become as pervasive as we see today.

In 1948, the invention of the semiconductor ’transistor’ revolutionized every aspect of the telephone industry, and indeed, the broader communications industry. Fragile and bulky vacuum tubes have been replaced by transistors. Compact, low-cost, rugged radios were developed. The first transistor radio went on sale in 1954 with four transistors, and the first portable, transistorized TV, in 1960, using 23 silicon and germanium transistors. In 1965, Intel’s Gordon Moore came up with what came to be known as Moore’s Law, which stated that the number of transistors on a chip would double about every two years. Sixty years later, Moore’s Law still holds surprisingly true.

In 1983, the first commercial mobile phone was powered by transistors. The path to miniaturization means that today, 45-nanometer electronic chips holding 820 million transistors are now possible.

The move from analogue to digital technology has had a major impact in the development of radio systems (see Figure). The first digital microwave links were in operation from the 1980s onwards, and the large-capacity systems from the 1990s, which were more robust to propagation impairment and interference, as well as transporting higher data capacity. Actions coordinated by ITU have been key in providing for countries to implement their analogue to digital switchover on a timely basis to allow the general public to enjoy the benefits of digital broadcasting. Digitalization quickly extended to all domains of radio applications, promoting convergence in fixed, mobile and broadcasting, and forcing regulatory regimes to adapt.

More recently, developments such as the push to broadband and the use of software-defined and cognitive radio systems are redefining the radiocommunication landscape. Once more, the impact of these factors on regulations have been the subject of continuous debate given, on the one hand, the increasing demand for spectrum resources and, on the other hand, the potential need for new paradigms of spectrum management at all levels.

Built on an elaborated combination of technical, legal and administrative treaty-based texts, the ITU international regulatory process has been responding in an effective and timely way to the ITU membership needs. Take for example the responsiveness of ITU radiocommunication conferences for spectrum and regulatory requirements of IMT, radio LANs (local area networks), high-altitude platforms, mobile satellite uses, emergency communication systems including aviation, and many other cases based on the current forty radio services described in the ITU Radio Regulations. In addition, several planning conferences have provided the appropriate spectrum and orbit assignment approach for some specialized communications services and applications.

Conclusions

The development of radiocommunications and spectrum management encompasses several marked transitions in the technology (including the invention of the semiconductor and microprocessor, the introduction of digitalization and convergence, trends of personalization and the push for broadband). Today, we are experiencing spectrum cognition in radio devices. At the same time, regulatory frameworks have evolved from being centrally planned and regulated, to a market-driven and what may ultimately become, a truly open radio environment.

During this period, radio has also broadly moved from utility-based to technology-based devices. Further, penetration rates show that wireless has evolved from an exclusive technology, which started out appearing in a few homes, later existing in almost every home, as the world’s most ubiquitous technology available to 6 billion people. Today, wireless is becoming a ’vanishing’ technology, as a core function embedded in every device.

The success of radiocommunications is thanks to the inventiveness of humankind in creating innovative technological solutions, but also to the responsiveness of ITU in evolving its international regulatory framework on a timely basis.


 

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