tailieunhanh - IP for 3G - (P2)

An Introduction to 3G Networks Introduction What exactly are 3G networks? 3G is short for Third Generation (Mobile System). Here is a quick run-down: † 1G, or first generation systems, were analogue and offered only a voice service – each country used a different system, in the UK TACS (Total Access Communications System) was introduced in 1980. 1G systems were not spectrally efficient, were very insecure against eavesdroppers, and offered no roaming possibilities (no use on holidays abroad.) | IP for 3G Networking Technologies for Mobile Communications Authored by Dave Wisely Phil Eardley Louise Burness Copyright 2002 John Wiley Sons Ltd ISBNs 0-471-48697-3 Hardback 0-470-84779-4 Electronic 2 An Introduction to 3G Networks Introduction What exactly are 3G networks 3G is short for Third Generation Mobile System . Here is a quick run-down 1G or first generation systems were analogue and offered only a voice service - each country used a different system in the UK TACS Total Access Communications System was introduced in 1980. 1G systems were not spectrally efficient were very insecure against eavesdroppers and offered no roaming possibilities no use on holidays abroad. . 2G heralded a digital voice and messaging service offered encrypted transmissions and was more spectrally efficient that 1G. GSM Global System for Mobile communication has become the dominant 2G standard and roaming is now possible between 150 countries where GSM is deployed. 3G - if the popular press is to be believed - will offer true broadband data video on demand videophones and high bandwidth games will all be available soon. 3G systems differ from the second generation voice and text messaging services that everybody is familiar with in terms of both the bandwidth and data capabilities that they will offer. 3G systems are due to be rolled out across the globe between 2002 and 2006. 3G will use a new spectrum around 2 GHz and the licences to operate 3G services in this spectrum have recently hit the headlines because of the huge amounts of money paid for licences by operators in the UK and Germany 50 billion or so . Other countries have raised less or given away licences in so-called beauty contests of potential operators 1 . 3G systems might be defined by the type of air interface the spectrum used the bandwidths that the user sees or the services offered. All have been used as 3G definitions at some point in time. In the first wave of deployment there will be only two flavours .