tailieunhanh - Nhiều giao thức truy cập đối với truyền thông di động P2

CELLULAR MOBILE COMMUNICATION SYSTEMS: FROM 1G TO 4G The basic principles of cellular communications were explained in the introductory chapter, and terms such as cluster size and reuse efficiency introduced. In the following, some more considerations on the advantages and limitations of the cellular concept will be made before reviewing first generation (1G) and second generation (2G) cellular communication systems. Moving on to 3G, we will first discuss the initial requirements according to which 3G systems were designed, and then to what extent they are likely to be satisfied by first releases of ‘true’ 3G systems on the one hand, and. | 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 2 CELLULAR MOBILE COMMUNICATION SYSTEMS FROM 1G TO 4G The basic principles of cellular communications were explained in the introductory chapter and terms such as cluster size and reuse efficiency introduced. In the following some more considerations on the advantages and limitations of the cellular concept will be made before reviewing first generation 1G and second generation 2G cellular communication systems. Moving on to 3G we will first discuss the initial requirements according to which 3G systems were designed and then to what extent they are likely to be satisfied by first releases of true 3G systems on the one hand and evolved 2G systems on the other. While special attention is paid to the GSM evolution route and to UMTS the initially European but now global proponent for 3G cellular communications evolutionary routes from cdmaOne to cdma2000 are also reviewed. The emergence of the Internet witnessed in the 1990s is expected to have a fundamental impact on the telecommunications industry including cellular communications. We will examine how this affects 3G what new requirements arise and how these can be met through subsequent releases of UMTS. Finally looking further into the future possible manifestations of 4G systems will also be discussed including the role wireless LAN technologies may play in this context. Advantages and Limitations of the Cellular Concept It was outlined in the previous chapter how the cellular concept allows use of the same set of frequencies in multiple cells and how it is in theory possible to arbitrarily increase capacity to match growing demand for wireless communication services through cell splitting. In practice however there are certain limitations. With smaller and smaller cells as a result of cell splitting it becomes increasingly .