Mobile Communications

The idea of cell-based mobile radio systems appeared at Bell Laboratories, in the USA, in the early 1970s. However, it was not until a decade later that such systems were introduced for commercial use. During the early 1980s, analogue cellular telephone systems experienced a very rapid growth in Europe, particularly in Scandinavia and the United Kingdom. Cellular-phone systems use the 800MHz (806 to 902 MHz) and 1.9GHz (1,850 to 1,990 MHz) frequency bands. The 1.9GHz frequencies are allocated to PCS (personal communication services), but many cellular systems use these frequencies as they bundle PCS capabilities on their voice-centric service.

The early, first generation cellular systems were analogue and operated in the 800MHz frequencies. Later extensions operated at 1.8GHz and in parts of North America at 1.9GHz. The second generation (2G) appeared about 10 years later, with the first digital mobile, circuit-switched networks. These systems provided better voice quality, higher capacity, lower power requirements and global roaming capabilities. They operated in both the 800MHz and the PCS bands.

Cellular systems use three different techniques for sharing an RF spectrum:

  • Frequency Division Multiple Access (FDMA)
  • Code Division Multiple Access (CDMA).

Of these, TDMA and CDMA are the dominant techniques.

Whilst take up was rapid, this led to a situation where – in the absence of standardisation – each company developed its own system. The undesirable consequences of this were a fragmented marketplace in which any given piece of equipment only operated within the boundaries of the country of manufacture. In order to overcome these problems, in 1982, the Conference of European Posts and Telecommunications (CEPT) formed the Groupe Sp飩al Mobile (GSM) in order to develop a pan-European mobile cellular radio system. The standardised system had to meet certain criteria:

  • Spectrum efficiency
  • International roaming
  • Low mobile and base stations costs
  • Good subjective voice quality
  • Compatibility with other systems such as ISDN (Integrated Services Digital Network)
  • Ability to support new services.

The decision was taken that the GSM system would be developed using digital technology, and “GSM” subsequently became the acronym for Global System for Mobile communications. In 1989 the responsibility for the GSM specifications passed from the CEPT to the European Telecommunications Standards Institute (ETSI). Phase I GSM specifications were published the following year, but the commercial use of the system did not start until the middle of 1991. In 1995 Phase 2 specifications extended coverage to rural areas, and by the end of that year approaching 120 networks were in operation in around 70 geographic areas.

By the start of the new millennium – notwithstanding the many bumps in the road along the way – significant progress had been made towards the so-called third generation (3G) of services:

  • the number of GSM subscribers worldwide had grown to an estimated 165 million
  • the first GPRS networks – an important migration step towards 3G networks – had gone live
  • the first WAP trials were underway in Europe.

By 2001, the promise of seamless inter-operation between the wireless world and the computing/Internet world and exciting new services such as video on demand was drawing ever closer.

PC Components | Processors (CPUs) | PC Data Storage | PC Multimedia | PC Input/Output | Communications | Mobile Computing

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