Mumbai University > Electronics and Telecommunication > Sem 7 > Mobile Communication

Marks: 10 M

Year: May 2012, May 2013, May 2014

1. The International Telecommunication Union (ITU), the United National (UN) organisation responsible for global telecommunication standards, has been working since 1986 toward developing an international standard for wireless access to worldwide telecommunication infrastructure. This standard is known as IMT 2000 or International Mobile Telecommunications 2000 (2000 indicates target availability year 2000 as well as the operational frequency band 2000 MHz range).
2. IMT2000 defines the third generation (3G) mobile telecommunication system which exhibits the following characteristics:
   • Seamless global mobility and service delivery.
   • Integration of the wire line and wireless network to provide telecommunication services transparently to the users.
   • Defining global standards that are flexible enough to meet local needs and to allow current regional/national systems to evolve smoothly towards third generation system.
3. The vision for an IMT200 system and its capabilities are:
   • Common spectrum world-wide (1.8 GHz-2.2 GHz band)
   • Multiple radio environment (cellular, cordless, satellite, LANs)
   • Wide range of telecommunication services (voice, data, multimedia and internet)
   • Flexible radio bearers for increased spectrum efficiency.
   • Data rates up to 2 Mbps for indoor environments.
   • Maximum use of IN capabilities.
   • Global seamless roaming.
   • Enhanced security and performance.
   • Integration of satellite and terrestrial systems.
4. IMT2000 service environments will address the full range of mobile and personal communication application. The scope of IMT2000 services include:
   • In building (pico cell)
   • Urban (micro cell)
   • Suburban (macro cell)
   • Global (satellite)
   • Communication types that include voice, data and images.
5. Radio aspects of IMT2000 are:
   • Uplink frequency: 1885-2025 MHz
   • Downlink frequency: 2110-2200 MHz
   • Transmission mode: FDD for mobile and satellite applications and TDD for indoor and pedestrian type applications.

1. A significant element of IMT2000 is the need to achieve a major improvement in spectrum efficiency compared to the currently available in the 2G mobile communication. In context of managing the access the spectrum, sharing a common pool of spectrum between operators and/or between terrestrial and satellite services is used to improve spectrum efficiency.
2. Key features of the radio access for IMT 2000 are:
   • High level of flexibility
   • Cost effectiveness in all operating environments
   • Commonality of design worldwide
   • Operation within the designated IMT 2000 frequency band
3. Global radio channels are scanned by IMT terminal to find the required information on available networks/standards and services. These channels carry information like bands used for IMT 2000, frequency rasters, modulation characteristics, guard bands, duplex direction and spacing, list of application services etc.
4. Network implementation of IMT 2000
   • As a stand-alone network with gateway and internetworking units towards supporting networks in particular towards PSTN, ISDN, and Packet DATA Networks.
   • It may be integrated with the fixed networks. In this functions needed to support specific radio network requirements are integrated to the fixed networks. Base stations are connected directly to a local exchange that can support IMT 2000 traffic by locally integrated functions and by accessing functions in other network elements.
   • Requirements for network functions must take into account the support of multimedia services.
   • IMT 2000 system should support global roaming and virtual home environment concept.
5. IMT 2000 service and network capabilities:
   • Circuit and packet bearer capability up to 144 kbps in vehicular radio environment, up to 384 kbps for pedestrian radio environment and up to 2048 kbps for indoor and office radio environment.
   • Interoperability and roaming among the IMT 2000 family of systems.
   • Service portability and support of virtual home environment.
   • Multimedia terminals and services.
   • Emergency and priority calls.
   • Separation of call and bearer channel/connection control.
   • User authentication and ciphering.
   • User-network and network-network authentication.
   • Geographic position/location service.
   • Lawfully authorised electronic surveillance.
6. IMT 2000 interfaces for specifications by the ITU
   • To ensure that systems belonging to different IMT 2000 family members can interoperate to provide seamless global roaming and service delivery.
   • MT-RAN interface requires the specifications not only of the physical radio interface but also of layer 2 and layer 3 protocols as well as support some supplication protocol that may be required across this interface.
   • In the initial implementation of IMT 2000 family systems operators may prefer to use RAN-CN interface based on existing wireless PCS systems.
   • The UIM-MT interface represents the interface between removable user identity module and the mobile terminal.
   • The CN-CN interface is key interface for supporting global roaming across networks belonging to different family members.