Английски език
The GSM system is undoubtedly the most successful second-generation digital mobile radio system. One of the key factors for this exceptional performance is the constant evolution of the GSM system and its derivatives. GSM: Evolution towards 3rd generation systems addresses new concepts in the GSM system, dealing both with standardized features as well as with theoretically and technologically feasible improvements which contribute to evolutionary changes in general. §Ongoing efforts in GSM standardization are focused on Phase 2+ with gradual additions for a fast and modular evolution. Speech remains the prime service of cellular systems, with ongoing work on spectral efficiency taking into account the tradeoff between cost of the system and transmission quality. Most of the notable results from novel speech service implementations are addressed herein such as new EFR speech codec and Advanced Speech Cell Items (ASCI). Data capability in Phase 2+ has been covered under General Packet Radio Service (GPRS) and High-Speed Circuit Switched Data (HCSD) work items. Initiatives under CAMEL cover intelligent networking (IN) within the GSM framework. §Dual mode operation in GSM includes not only dual-band solutions but also inter-networking with other systems like DECT or satellite systems. Numerous specific wireless applications such as inbuilding communications, WLL, etc., have also been developed based on GSM. To support the required changes a number of issues have to be solved in the radio part of the system. Deployment of adaptive antenna arrays for enhanced quality, interference suppression techniques and slow frequency hopping are among the techniques presented in the GSM framework. §Dynamic evolution of GSM presents a platform for the introduction of UMTS. Presently, efforts are directed towards the standardization of the UMTS air interface in ETSI. Major trends in progress towards new radio interfaces are outlined including contributions from pan-European projects such as ATDMA, which was carried out under the RACE II framework, and the ACTS project AC090 FRAMES. §GSM: Evolution towards 3rd generation systems comprises a collection of specially written contributions from GSM specialists. The information presented is essential reading for all researchers, engineers and managers working on GSM and third generation wireless systems. This book covers the most important advances in GSM that will have lasting impact on the system influencing third generation wireless systems.
