Second Generation (GSM) [Return to main Technology page]

A committee at the conference of European Posts and Telecommunications Administrations (CEPT) conceived Pan-European Cellular Mobile Radio System in 1982. The committee aimed to achieve four main goals.

1) Provision of cellular services, which provide more functionality than analogue networks.

2) Provision of new capacity to alleviate capacity shortage in metropolitan analogue networks.

3) To develop, through Pan European Co-operation, a pool of technological expertise which would enhance Europe's ability to compete with US and Japan.

4) To forward the European Commission's goals of universal telecommunications standardisation and access in Europe thus opening up markets on the scale of the US.

A working party called Groupe Speciale Mobile was tasked with the development of the standards. The standard that has emerged from this group has become widely known as GSM. In 1989 GSM was transferred from CEPT to the European Telecommunications Standards Institute (ETSI). CEPT however continues to provide a forum for European telecommunications standardisation.

Development over the years lead to a digital system using Time Division Multiple Access (TDMA). This was known as Primary GSM (P-GSM), which was split between two operators Cellnet and Vodafone in the UK. In response to a perceived future demand for even more capacity, P-GSM spectrum was extended to form E-GSM. At a late stage in GSM development the existing technology was modified to meet the need for PCN networks. This is known as DCS 1800 and is mainly used by One2One and Orange in the UK. The DTI agreed to release more spectrum in the DCS 1800 range for dual-band operation in the UK. This allowed GSM 900 operators such as Cellnet and Vodafone to establish a system using both 900Mhz and 1800Mhz frequencies. This brought major advantages by offering additional network capacity, but required dual band handsets. However the DTI also increased spectrum available in the UK for the two DCS 1800 operators One2One and Orange.

Short Message Service (SMS)

This is available in all of the digital systems such as GSM, GPRS, EDGE and UMTS. It is one of the early packet data type for transport of short text messages from the mobile to the network, and from the network to the mobile. The traditional SMS also includes Cell Broadcast, which is the ability for the network to transmit information to the mobile. SMS can also be used as a general-purpose bearer such as the WAP protocol. It is also integrated into larger value added services such as integrated messaging services, e-mail delivery and notification, and status messages.

Wireless Application Protocol (WAP)

This is a collection of protocols and transport layers that allow mobile and portable communication devices such as Personal Digital Assistants (PDA's) to receive information over the airwaves similar to computer users obtaining information over the Internet. SMS data messages can be incorporated into WAP to provide different services. Also General Packet Radio Service (GPRS) can provide an ideal mechanism for WAP services. Current WAP mobile services are slow and restricted due to capacity limitations. Hence the success of WAP in mobile communication will depend on how it can be adapted to serve new emerging technologies.

General Packet Radio Service (GPRS)

The European Telecommunications Standards Institute (ETSI) has developed GPRS technology to make data across the GSM network, fast and more attractive. This is still a technology under development and most of the UK operators are planning to upgrade their networks. GPRS can be much faster than other traffic on GSM but the exact speed a single user sees will be directly related to the total number of users in a particular cell. However most GPRS transactions will be short hence reducing any delays. GPRS is designed for the internet hence internet services such as File Transfer Protocol (FTP), Web browsing, Internet chat will be possible at very fast speeds. It will also be an ideal mechanism for WAP. The operators will benefit from new revenue generating streams requiring short exchanges of information like telematic type applications such as automatic tollbooths. Other uses can be to check your bank balance or to initiate a fund transfer to pay bills. The potential for GPRS is immense and is considered to be a step towards UMTS the next generation of mobile technology.

Basic System Parameters

Frequency Band for DCS 1800 (UK)
1710 - 1785 Mhz mobile Tx
1805 - 1880 Mhz base Tx

Channel Spacing
200Khz, 374 Carriers, 8/16 Users per carrier

Duplex Spacing
95 Mhz, Frequency Division Duplexing (FDD)

Signalling Modulation
Gausian Minimum Shift Keying (GMSK) modulation

Signalling
270 Kbits/s, Time Division Multiple Access (TDMA)

Digital Speech Coding
Regular Pulse Excitation, Linear Predictive Coder (RPE-LPC), 13Kb/s, 6.5kb/s & 12.2Kb/s

Enhanced Data Rates for Digital Evolution (EDGE)

This is a new modification to GSM incorporating a change to the physical layer. The main advantage is that it gives higher data rates up to 384 Kb/s.

Bluetooth

This is a technology specification for small form factor, low cost, short-range radio links between mobile PCs, mobile phones and other portable devices such as Personal Digital Assistants (PDA's) etc.