Mobile Communications and Mobile Data Technologies

This report is a technical introduction, for people without an engineering background, to digital cellular mobile technologies. These are the basis of huge and growing industries for voice and increasingly data communications, with cellular handsets becoming the most widely used electronic product in history.

We begin with an introduction to the 1G and early digital technologies AMPS, IS-136 TDMA and IS-95 CDMA. We discuss GSM and its high speed data enhancements, including HSCSD GPRS and EDGE. We discuss the UMTS (Universal Mobile Telecommunications Service) Wideband Code Division Multiple Access (WCDMA) 3G technologies. These are based on the GSM network architecture and together with GSM are the most widely used technologies on a global basis.

We also discuss the Japanese FOMA WCDMA system, which was the basis for UMTS WCDMA, and CDMA2000 and its high speed data enhancement EV-DO (Evolution Data Only) which are the dominant 3G technologies in North America and many other non-European countries. We provide tutorials on convolutional coding and the spreading and scrambling processes which are at the heart of Code Division Multiple Access (CDMA) spread-spectrum techniques.

We discuss services which operate similarly or identically over all 2.5G and 3G networks, including SMS text messaging, Multimedia Messaging Service (MMS) and Wireless Application Protocol (WAP). We discuss the IP Media Subsystem (IMS) – a centrally managed network architecture which is the basis for providing a number of services including instant messaging with presence, Push-to-Talk over Cellular (PoC), VoIP and location based services, irrespective of the underlying 2.5G or 3G network technology.

Base-stations and their backhaul network are the most expensive part of cellular systems. We discuss the various approaches to base-stations, including the conventional large, tower-based ‘macro-node’, and alternatives for smaller areas and enclosed spaces, including ‘micro-nodes’ and ‘pico-nodes’. We conclude this discussion with a detailed evaluation of the emerging ‘femtocell’ technology: the ability to place a small base-station in a home or office, using the owner’s ADSL or HFC cable modem service for backhaul. This is based on the new Generic Access Network (GAN) standards, which arose initially from the desire to achieve Fixed Mobile Convergence (FMC) via unlicensed frequencies, with Bluetooth and WiFi approaches.

We discuss the long-term development of the two major 3G technologies into 4G mobile systems, with similar OFDM-based modulation schemes and performance to fixed and mobile WiMAX. We consider the challenge the 4G development of UMTS poses to CDMA2000’s 4G Ultra Mobile Broadband and to the widespread adoption of WiMAX.

Broadcasting or multicasting to handheld devices can be achieved with a unidirectional system with separate frequencies such as Eureka 147 Terrestrial Digital Mobile Broadcasting (T-DMB), DVB-H or Qualcomm’s FLO (Forward Link Only). Alternatively, it can be achieved with data packets within the cellular technology, perhaps with OFDM modulation to increase data density, as is possible with EV-DO. We discuss these and other approaches to this important addition to mobile technology.

We also discuss the major audio visual coding technologies, otherwise known as data compression, for sound, video and multimedia material. An increasing number of these technologies are utilised in 3G services and in mobile broadcasting.

Cellular mobile technology is a complex and rapidly developing field. This report is intended to give non-specialists a comprehensive technical introduction to current and emerging mobile cellular technologies. This report is intended to enable readers to understand current usage and foresee likely developments relevant to their own domains, such as telecommunications regulation, investment and management.