49. 1.3 European 900 mHz analogue standard

Another body of opinion in Europe took a somewhat longer view of the potential of cordlessness, in terms of its potential demand on radio spectrum when the number of cordless terminals exceeded about 10% of normal wired terminals. This vision resulted in the following standard, that has been adopted in most CEPT affiliated countries, with the exception of the UK and France who chose the h. f/v. h. f. option that offered a significantly lower production cost. The CEPT standard has the following general characteristics:

1. Analogue FM operation.

2. Forty 25 kHz duplex channels in the frequency bands 914-915 MHz paired with 959-960 MHz.

3. Radiated power limited to 10mW.

4. Dynamic channel selection (DCS) on call set up.

This last feature sets араrt this standard from the earlier technol­ogy. On call set up either from a base (incoming call) or handset (outgoing call) all forty channels are scanned in order to select a vacant radio channel, or one where the co-channel interference is acceptable low, on which to set up the telephone call.

This feature has a complexity burden but results in all users being able to use any available radio channel. Therefore spectrum efficiency in terms of traffic carried per megahertz per square kilometre is very much increased compared to a factory set single channel system of the type considered in the last section. The benefits of DCS shows when the total cordless traffic demand in a localised area is such that co-channel interference from other users becomes the dominating factor in terms of speech quality and range of operation.

Technically the CEPT standard is a major step forward in cordless product design but is consequently more expensive than the far simpler h. f. /v. h. f. analogue design. It has, therefore, not achieved the degree of market penetration throughout Europe as its proposers had originally predicted.

49. 2 Digital technology

The analogue cordless telephone has succeeded in opening up the market for localised mobility around the home or place of work, without incurring the costs and regulation associated with a fully mobile cellular radio service. However, its analogue nature and, in its more successful form, limited traffic carrying capabilities se­verely limited its full development potential. What was needed was a ubiquitous technology that could be exploited widely in the home, office and factory, in such numbers that all could benefit from the economies of scale that mass uniform production can provide. The new generation needed the characteristics as in the following sec­tions.

49. 2. 1 Areas of application

1. Residential, private use in houses and apartments.

2. Small CT systems for office use.

3. Large CT systems, multi-cell private switch telephony based building mobile systems with roaming and in-call handover between cells (the so-called cordless business communications system, CBCS). 4 .Radio access to local public and other telecommunications networks, e. g. telepoint systems. The CBCS opens the opportunity towards the cordless office with greater freedom to rearrange office space as work demands. This is a result of reduced telecommunications wiring needs and costs. However radio coverage over the entire service area must be good enough to ensure that the probability of a call being set up exceeds 99% otherwise users expectations, based on the performance of wired telephones, will not be met.

Telepoint is a service provided to cordless handset owners from cordless base stations located in public places, e. g. railway stations, shopping precincts, fast-food restaurants etc. This is a basic public communication service for the less migratory more localised sector of the travelling market and thus does not compete directly with the wide roaming mobile cellular network. Hence a handset purchased for use in the home and/or work place can also be used to gain access to a telepoint service whilst the user is in transit between them.