- •1.1 Introduction
- •1.2 Cellular Fundamentals
- •1.2.1 Communication Using Base Stations
- •1.2.1.1 A Call from a Mobile
- •1.2.1.2 A Call to a Mobile
- •1.2.1.3 Registration
- •1.2.2 Channel Characteristics
- •1.2.2.1 Fading Channels
- •1.2.2.2 Doppler Spread
- •1.2.2.3 Delay Spread
- •1.2.2.4 Link Budget and Path Loss
- •1.2.3 Multiple Access Schemes
- •1.2.3.1 Frequency Division Multiple Access Scheme
- •1.2.3.2 Time Division Multiple Access Scheme
- •1.2.3.3 Code Division Multiple Access Scheme
- •1.2.3.4 Comparison of Different Multiple Access Schemes
- •1.2.3.5 Space Division Multiple Access
- •1.2.4 Channel Reuse
- •1.2.5.1 Macrocell System
- •1.2.5.2 Microcell Systems
- •1.2.5.3 Picocell Systems
- •1.2.5.4 Overlayed System
- •1.2.6 Channel Allocation and Assignment
- •1.2.6.1 Fixed Channel Allocation Schemes
- •1.2.6.2 Dynamic Channel Allocation Schemes
- •1.2.6.3 Hybrid Channel Allocation Schemes
- •1.2.7 Handoff
- •1.2.7.1 Network-Controlled Handoff
- •1.2.7.2 Mobile-Controlled Handoff
- •1.2.7.3 Mobile-Assisted Handoff
- •1.2.7.4 Hard Handoff and Soft Handoff
- •1.2.8 Cell Splitting and Cell Sectorization
- •1.2.9 Power Control
- •1.3 First-Generation Systems
- •1.3.1 Characteristics of Advanced Mobile Phone Service
- •1.3.2 Call Processing
- •1.4 Second-Generation Systems
- •1.4.1 United States Digital Cellular (Interim Standard-54)
- •1.4.2 Personal Digital Cellular System
- •1.4.4 Pan European Global System for Mobile Communications
- •1.4.5.1 Multiple Access Scheme
- •1.4.5.2 Common Channels
- •1.4.5.3 Burst Format
- •1.4.5 Cordless Mobiles
- •1.5 Third-Generation Systems
- •1.5.3 Planning Considerations
- •1.5.3.1 Radio Access
- •1.5.3.2 Spectrum Requirements
- •1.5.3.3 Security
- •1.5.3.4 Intelligent Networks
- •1.5.3.5 Regulatory Environments
- •1.5.4 Satellite Operation
- •References
1.5.3.4 Intelligent Networks
The standardization of IMT-2000 is considering new and evolving technologies on the telecommunications network side, such as intelligent networks (INs). IMT-2000 network issues are studied in close cooperation by ITU-R/ITU-T and to a great extent as an integral part of ITU-T work on IN concepts and capabilities. It is anticipated that future versions of IN switching and signaling standards will include the management of mobile and radio access as a natural part of the protocols. This includes location registration/updating and paging as well as the various types of handover between radio cells [68].
1.5.3.5 Regulatory Environments
The regulatory considerations for the introduction and use of IMT-2000 include determining the conditions for regulated and nonregulated systems, spectrum sharing, identifying the number of operators and service providers, licensing procedures, and call charging. The provision and establishment of IMT2000 is subject to the regulatory process in each country’s telecommunications authority. It may be necessary to develop new regulatory environments for IMT-2000, which will enable the provision of new services in a variety of ways not anticipated by existing regulations.
1.5.4 Satellite Operation
The satellite component of IMT-2000 enhances the overall coverage and attractiveness of the service and facilitates the development of telecommunications services in developing countries [74]. Satellites are particularly useful in mobile communications because they are able to achieve coverage of very large areas of the earth’s surface [75]. To provide service at an acceptable cost, the catchment area must include as many users as possible. In this situation a globally unique standard formulated by IMT-2000 is preferable to adopting regional solutions [58]. The current version of the recommendation pertaining to the satellite component of IMT-2000 is very generic and does not provide specific details in relation to service, equipment, architecture, or interfaces and protocols [76].
Currently many satellite PCSs have been proposed based on constellations of orbiting satellites offering continental and worldwide communications, data, tracking, and paging services. The experience gained from these networks in the next few years will provide valuable input into the satellite component of third-generation systems. Depending on the lessons learned, the three possible levels of integration of the satellite component into the terrestrial network include
1.Network integration at the call level
2.Equipment integration, requiring common service standards and dual-mode terminals
3.System integration, where the satellite is an integral part of the network and handoff can be supported between terrestrial and satellite megacells [75]
It is anticipated that IMT-2000 will use several satellite constellations, each comprising a number of satellites, radio (service) links from the satellite to the IMT-2000 terminal, and radio (feeder) links from the satellites to the land earth stations (LESs) [77]. Because the satellite component will have a limited number of LESs, the operation of the network will inherently involve international terrestrial connections, and access to the network may therefore also involve an international connection. A number of nongeostationary earth orbit (GEO) satellites based on low/mid-earth orbit (LEO/MEO) constellations have been or are being deployed to deliver mobile voice and broadband data services. For the first time at WRC-1997, spectrum was made available for the operation of these satellites and a provisional power limit was imposed so that they could share the spectrum with GEO satellites. Studies conducted since 1997 on spectrum sharing have found in favor of the concept and the WRC-2000 has decided to limit the power of non-GEO satellites to enable their co-existence with GEO satellites, which aim to provide high-speed local access to global broadband services without unacceptable interference [78].
Continuity of coverage will be provided by contiguous footprints of spot beams from one or more satellites in a constellation. For nongeostationary satellites, these footprints will be in motion and continuity of calls in progress will be achieved by handover between beams, using functionality in both the mobile and satellite components [77].
© 2002 by CRC Press LLC