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10/5/2009
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A general term, in telecommunications taken to mean any signals transmitted or stored in the network. It usually becomes much more specific when associated with another word or other words, of which some examples follow:
Information appliance - a device used to access information, including computers, personal digital assistants, mobile phones etc.
Information and communications technologies (ICT) - a title used by the UK Department of Trade and Industry and many others to cover a wide range of technologies used in the computing, information and communications industries.
Instant Messaging is a real-time (where in this context real-time means the IT definition of less than a few seconds - not always the same as telecoms real-time where milliseconds count) text-based communications application, which includes a unique feature , that of conveying “presence” information about users to their friends and work colleagues – whether they are online or offline, on the phone, away from their desk or even at lunch.
Integrated Access Device (IAD)
A fairly generic term implying a piece of equipment that aggregates a variety of services and channels (e.g. PSTN and data leased lines) from a customer onto a single path into the carriers network. Numerous equipment suppliers classify one or more of their products in this category and in practice it covers a wide range of functionality. One of the first examples in the late 1980's was BT's Flexible Access System (presented at the ISSLS 88 conference) which was used with optical-fibres to deliver multiple services to major customers.
Integrated Services Digital Network (ISDN)
The completion of digitalisation of the network by the conversion of switching systems and core transmission to wholly digital systems resulted in what became known as the Integrated Digital Network (IDN). The next step was to take digital channels all the way to the customer through the access network so that all services could be integrated on one bearer. This became known as the Integrated Services Digital Network (ISDN), a term invented in 1971 by the relevant standards group (CCITT Study Group XI), although the standards were not published until 1984.
The access part for basic-rate ISDN (BRI) comprises two 64 kbit/s communications B-channels and a 16 kbit/s D-channel for signalling and access to packet-switching services. The resulting 144 kbit/s signal is transmitted over a single copper pair using an agreed transmission system built into the exchange line-card at one end and the network terminating equipment at the other. In the USA the network terminating equipment was deregulated from the outset and the wire interface was therefore defined as well.
There was also primary-rate ISDN (PRI) which was for the interconnection of PABXs to the network at 1.5 Mbit/s (N. America) and 2 Mbit/s (rest of world). These carried up to 24 or 30 64 kbit/s channels respectively with related D-channels although the major use of this turned out to be for digital voice connectivity. At the time there were few digital (non-speech) services and so the standards defining ISDN included a wide range of services as well as the technical infrastructure. The services were categorised into bearer services, teleservices and supplementary services.
A wide ranging term. In telecommunications it usually means bringing together a number of sub-systems to provide a service or end-to-end network capability. However the term applies to all levels of building up a system from individual components through all the intermediate modules to the network as a whole. For example a chip will be integrated with other components on a circuit board and then the circuit board may be integrated with others to make a piece of equipment. That equipment may then be integrated with other equipment to form an end-to-end communications capability. That will then be integrated with operational support systems and then integrated into manual procedures for the people operating the operational support systems. At all stages tests will be made to ensure the requirements of the component, sub-system or system are met and this is called integration testing.
See also testing and systems integration.
A general term for the legal rights protecting innovation. The term IPR is widely used for intellectual property rights. In the UK there are six major forms of IPR - confidential information, copyright, design rights, patents, registered designs and trade marks.
The traditional role of IPR has been to protect innovation for the originator to exploit or licence. This can lead to commercial advantage through a proprietary product but in the complex interactive worlds of telecommunications and ICT it can also lead to disadvantage where a network, service or product does not comply to standards. Many purchasers of networks, systems and software require inter-working at many levels, as well as second source suppliers to retain competitive purchasing, and use standards to achieve this. The balance between proprietary solutions and standards based solutions is therefore a constant tension when standards must embrace pre-existing IP. An alternative methodology for developing standards is the open source approach.
References (books):
Intellectual property rights for engineers.
The Standards Edge: Dynamic Tension.
The most common forms of intelligence in networks and computers can broadly be summarised as Artificial intelligence (AI) and Network Intelligence, of which the main form is the Intelligent Network (IN), sometimes known as a smart network. Intelligence is often equated with the word smart: as in smart cards, smart radios and smart spectrum. The components making a network intelligent are sometimes referred to as network smarts.
An intelligent network means different things to different people. Some interpret it widely as a network that finds you, talks to you and knows what you want - trying to emulate the human operator driven network of the pre-automated very early part of the 20th Century. Some see it in terms of the separation of service control logic from core-network routing logic in the manner encapsulated by the various standards bodies - perhaps the most conventional interpretation of the Intelligent Network (IN). Others see it simply as the convergence of telecommunications and computing, something that has been happening for a long time but with much further still to go.
For a full explanation see Intelligent networks, standards and services, BTTJ Vol 13, No 2.
A means of combining channels in a digital signal stream. The digital signals can be interleaved in various ways such as at bit level or byte level. Interleaving is a fundamental process in time division multiplexing. See pulse code modulation systems.
International Telecommunications Union (ITU)
The ITU, headquartered in Geneva, Switzerland is an international organisation under the aegis of the United Nations where governments and the private sector co-ordinate global telecommunications networks and services. There are three main areas of activity: Radiocommunication (known as ITU-R), Telecom Development (known as ITU-D) and Telecom standardisation (known as ITU-T).
The ITU-R and ITU-T are well known for a variety of published standards (in old literature they may respectively be referred to as CCIRR and CCITT). An index of the main areas can be found here.
Internet/Internet Protocol (IP)
The term internet is a contraction of internetworking - and what we now know as the Internet with a capital I is just that: a network of networks. The essence of it lies in the ability to interconnect networks of computers, which in some cases are single computers, across the world. This is done through a transmission and routing infrastructure for the data signals and by the use of a common protocol for the exchange of information, called TCP/IP (transmission control protocol/internet protocol). What most people know as the Internet is the publicly available data equivalent of the voice orientated public switched telephone service (PSTN). As such it is one of the four big telecommunications network technologies and structures (PSTN, Internet, cellular and cable-TV). All of these inter-relate in terms of components, technologies, design and services and are what this Encyclopedia is about, so there are numerous entries applicable to the Internet.
The basic concepts and terms in IP networking, covering the fundamental principles of packet switching through to the devices, protocols, technologies and applications used to create an IP network are given in An Introduction to IP networks, BTTJ, Vol 18, No 3.
The following provide more detailed information: An overview of Internet protocols, BTTJ, Vol 16, No 1, The challenges of building a carrier-scale IP network, BTTJ Vol 18, No 3, IP address management, BTTJ, Vol 18, No 3, routing, history. Like other networks there are private versions (intranets) and virtual private versions (IP VPNs, IP Virtual private networks, BTTJ, Vol 18, No 3)
See compiler
Intersymbol interference (ISI)
See symbol.
A private version of the Internet for use within an enterprise but using common Internet protocols and network technologies and possibly with connection to the Internet in a controlled way via firewalls to preserve the security of the information held. May be extended to some trusted customers and suppliers with an extranet.
A layer of air, surrounding the earth, which is ionised, i.e. it consists of charged gases which provide conducting layers. The layers vary in thickness from 50 - 400 km above the earth and they have different effects on radio signals in different parts of the radio spectrum. Low frequency signals travel as ground waves, then, as the frequency increases the waves travel in the space between earth and the ionosphere, at higher frequencies the waves are reflected from the ionosphere as sky waves (diagram) . Atmospheric conditions and the frequency of a signal will affect the reflectivity and opportunities for multiple-hops of sky waves and hence the distance the signal can travel. Conditions can be affected by day and night as well as sunspots. Very high frequencies pass straight through the ionosphere resulting in essentially short or even line of sight paths. See also propagation, troposphere and space waves.
Internet protocol, security. A form of IP with added security measures, notably to enhance authentication of the user.
An isochronous digital signal is a digital signal in which the time intervals between significant instants have he same duration or durations which are integer multiples of the shortest one. Standard signals are always isochronous e.g. the HDB3 coded 2.048 Mbit/s. See also anisochronous, asynchronous, heterochronous, mesochronous, plesiochronous, and synchronous.
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