An important dimension to the Universal Mobile Telecommunications Standard is the upgrade path from current Global System for Mobile Communications systems. Of particular interest is the data capacity. GSM currently provides just 9,600 bits per second (the amount of information it is possible to send), less than 25% of the rate typically achievable with a modem over a fixed line, and barely adequate for more than basic text e-mail.
The first significant increase is currently being introduced in the UK, and goes by the name of High-Speed Circuit-Switched Data. This works by boosting the time slots GSM normally allocates per subscriber (one slot at the present time) and amalgamating them so one subscriber can use up to four. This will provide 56kbits of information to be sent, per second.
Following HSCSD, the next leap forward will be the General Packet Radio Services. This will provide data-rates up to 115kbit per second. GPRS is expected within 18 months in the UK. All these enhancements will work in the existing GSM frequency bands, and will follow the existing system of roaming between cells. The next step, UMTS, uses new frequency bands, and will be introduced in my next column.
For further details on mobile-phone developments, see: http://www.zdnet.co.uk/itweek/brief/1999/11/wireless_data/