4G TECHNOLOGY

The major driver to change in the mobile area in the last ten years has been the massive enabling implications of digital technology, both in digital signal processing and in service provision. The equivalent driver now, and in the next five years, will be the all pervasiveness of software in both networks and terminals. The digital revolution is well underway and we stand at the doorway to the software revolution. Accompanying these changes are societal developments involving the extensions in the use of mobiles. Starting out from speech-dominated services we are now experiencing massive growth in applications involving SMS (Short Message Service) together with the start of Internet applications using WAP (Wireless Application Protocol) and i-mode. The mobile phone has not only followed the watch, the calculator and the organiser as an essential personal accessory but has subsumed all of them. With the new Internet extensions it will also lead to a convergence of the PC, hi-fl and television and provide mobility to facilities previously only available on one network.

The development from first generation analogue systems (1985) to second generation (2G) digital GSM (1992) was the heart of the digital revolution. But much more than this it was a huge success for standardisation emanating from Europe and gradually spreading globally.

However, world-wide roaming still presents some problems with pockets of US standards IS-95 (a code division multiple access [CDMA] rather than a time division multiple access [TDMA] digital system) and IS- 136 (a TDMA variant) still entrenched in some countries. Extensions to GSM (2G) via GPRS (General Packet Radio Service) and EDGE (Enhanced Data rates for GSM Evolution) (E-GPRS) as well as WAP and i-mode (so called 2.5G) will allow the transmission of higher data rates as well as speech prior to the introduction of 3G.

Mobile systems comprise a radio access together with a supporting core network. In GSM the latter is characterised by MAP (Mobile Applications Protocol), which provides the mobility management features of the system.

GSM was designed for digital speech services or for low bit rate data that could fit into a speech channel (e.g. 9.6kbit/s). It is a circuit rather than a packet oriented network and hence is inefficient for data communications. To address the rapid popularity increase of Internet services, GPRS is being added to GSM to allow packet (Internet Protocol [IP]) communications at up to about 100kbit/s.

Third generation (3G) systems were standardised in 1999. These include IMT-2000 (International Mobile Telecommunications 2000), which was standardised within ITU-R and includes the UMTS (Universal Mobile Telecommunications System) European standard from ETSI (European Telecommunications Standards Institute), the US derived CDMA 2000 and the Japanese NTT DoCoMo W-CDMA (Wideband Code Division Multiple Access) system. Such systems extend services to (multirate) high-quality multimedia and to convergent networks of fixed, cellular and satellite components. The radio air interface standards are based upon W-CDMA (UTRA FDD and UTRA TDD in UMTS, multicarrier CDMA 2000 and single carrier UWC-136 on derived US standards). The core network has not been standardised, but a group of three—evolved GSM (MAP), evolved ANSI-41 (from the American National Standards Institute) and IP-based— are all candidates. 3G is also about a diversity of terminal types, including many non-voice terminals, such as those embedded in all sorts of consumer products. Bluetooth (another standard not within the 3G orbit, but likely to be associated with it) is a short-range system that addresses such applications. Thus services from a few bits per second up to 2Mbit/s can be envisioned.