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Nhiều giao thức truy cập đối với truyền thông di động P11

TOWARDS ‘ALL IP’ AND SOME CONCLUDING REMARKS This concluding chapter provides first an introduction to some of the planned release 5 enhancements to UMTS and the GPRS/EDGE RAN (GERAN). These can be seen as the first step towards ‘all IP’. The challenges when having to deliver real-time IP services over an air interface, in particular voice over IP services, are summarised and possible solutions to achieve spectrum efficiencies similar to those of optimised cellular voice services are outlined. Unlike the UTRA modes, the GSM/GPRS air interface was not designed to handle real-time packet-data traffic. Further enhancements are required to support real-time. | Multiple Access Protocols for Mobile Communications GPRS UMTS and Beyond Alex Brand Hamid Aghvami Copyright 2002 John Wiley Sons Ltd ISBNs 0-471-49877-7 Hardback 0-470-84622-4 Electronic 11 TOWARDS ALL IP AND SOME CONCLUDING REMARKS This concluding chapter provides first an introduction to some of the planned release 5 enhancements to UMTS and the GPRS EDGE RAN GERAN . These can be seen as the first step towards all IP . The challenges when having to deliver real-time IP services over an air interface in particular voice over IP services are summarised and possible solutions to achieve spectrum efficiencies similar to those of optimised cellular voice services are outlined. Unlike the UTRA modes the GSM GPRS air interface was not designed to handle real-time packet-data traffic. Further enhancements are required to support real-time IP bearers in GERAN. Possible alternatives are discussed and planned solutions are briefly described. The last section provides summarising comments on multiplexing efficiency and access control two key topics that kept reappearing throughout this book for TDMA hybrid CDMA TDMA and CDMA systems. 11.1 Towards All IP UMTS and GPRS GERAN Release 5 In early 1999 a few operators and infrastructure manufacturers got together to form 3G.IP 92 an industrial lobby group intended to influence 3GPP for UMTS and ETSI for EDGE GPRS towards adoption of what was then termed an all IP network architecture. This further evolved GPRS architecture based on packet technologies and IP telephony would function as a common core network to access networks based on both EDGE and WCDMA radio access technologies. The system would have to be able to deliver IP-based multimedia services efficiently requiring also enhancements to the air interface. One of the main benefits provided by IP technology is the service flexibility as already identified in Section 2.4. Another motivating factor for some operators is the wish to focus exclusively on the packet-switched .