The article gives an outline about the mobile radio standards Global System for Mobile Communication (GSM), Global Packet Radio Service (GPRS) and Universal Mobile Telecommunication System (UMTS).

Content:

• 1. Introduction
• 2. GSM Standard (Global System for Mobile Communication)
• 3. GPRS Standard (General Packet Radio Service)
• 4. UMTS Standard (Universal Mobile Telecommunication System)

The meaning of with mobile systems is humongous for ubiquitous availability. Milllions of people are processed payments, are made communication and are exchanged some information with other people by the mobile systems over great distance. The mobile system supports these activities independent on location and time (business anytime and anywhere). Therefore mobile computing and ubiquitous availability is in the field of business, essential (e. g. electronic commerce). For a reliable radio communication it is necessary to install a lot of base stations which uses the cellular technique. The entire area is divided into cells and radio zones respectively. Every cell operates in a packet of frequencies in which spatial and surrounding zones does not work. Furthermore such a topology is supported by the technique of handover and roaming. Handover allows a automatically frequency shift keying during the change from one cell to a another or at unpropitious transmission conditions. Compared to handover the roaming technique enables mobile devices to move from one radio cell to another with intelligent network functions and access points. In the following sections describes the mobile system standards GSM (Global System for Mobile Communication), GPS (General Packet Radio Service) and UMTS (Universal Mobile Telecommunication System).

The GSM standard describes a cellular phone network system with a data transmission rate of 9.6 kbit/s. It comprises modern functionalities such as knock, line holding and SMS (till 160 characters). Further, it is a digital mobile radio network and uses the GSM frequency band between 900 MHz and 1800 MHz. Each of the GSM frequency band is divided into several channels, which do not interact with each other.

For example the frequency band of 900-MHz is divided into 124 channels with a bandwidth of 200 kHz among each other. That fragmentation is called Frequency Division Multiple Access (FDMA). In combination with a Time Division Multiple Access (TDMA) there is a effective utilisation within the channels [tecchan03]. For every connection two channels for a concurrent transmitting and receiving which are needed. Which is called duplex channel. Therefore the frequency domain is divided into a uplink (mobile station to base station) at 890-915 MHz and downlink (base station to mobile station) at 935-960 MHz.

The GPRS standard is a further development of the GSM standard. In general it supports a advanced data transmission rate of 170kbit/s than GSM. Further GPRS uses a package oriented data transmission technique and is in particular suitable for IP based services.

UMTS is deemed to be the successor of GSM and GPRS. In the future it will be possible to surf wireless in the internet, transact video conferences and mobile commerce (mCommerce). Therefore it is necessary to get a higher data transfer rate than with GSM or GPRS. Furthermore is the main object of UTMS to combine the private, business and public sector application area into a homogenous communication level (uniform mobile system infrastructure). A UMTS terminal will support the GSM standard with 900 MHz and 1800 MHz. If a UMTS terminal quits a UMTS cell there is automatically a handover into a GSM cellular network. It has a range which is similar to GSM/GPRS and uses a packet-orientated data transmission.

UMTS based on the WCDMA technology (Wideband Code Division Multiplexing Access). WCDMA comprises the possibility for the receiver to filter out its signal of any sent signal within the same frequency band with a specific data coding. The data coding is defined between receiver and transmitter. Every connection get a individual code for delimitation from another connection. The data transmission rate of UTMS comprises 2 Mbit/s and uses a bandwidth of 5 MHz. But the maximum allowable transmission rate is only available within a range of a UMTS cellular station and there are no any environmental influences. Further is is necessary to generate a new generation of multimedia terminals because today’s GSM/GPRS mobile phones (voice communication) can not to be used on the basis of UMTS (multimedia), because UTMS devices require a higher computing power, battery capacity and larger color screens.