ADSL2 The Next Generation
ADSL2 or ADSL2+ is the next step in the evolution of ADSL. Currently it is not a ratified standard so we will not be seeing in deployed on the UK Local Loop, but it is set to supersede the existing G.DMT and G.Lite standards.
What does ADSL2 promise, well the frequency range used now tops out at 2.2MHz, which means up to 20Mbps downstream speed if a line is less than 8000 feet (~2.5km) and at existing speeds adds an extra 600 feet to the reach of the service. Interestingly it is designed to be interoperable with existing ADSL services, though whether existing DSLAMs will support it via simple firmware upgrades is unclear at this time.
Some of the failings of ADSL are also addressed, in particular with ADSL2 it will be possible to bond lines to produce a true 30 or 40Mbps downstream. Bonding is very attractive for people near the edge of ADSL reach, since any single line is heavily speed limited, but by providing two lines they could obtain the same speeds as someone nearer the exchange. To improve the deployment and fault finding stages of ADSL, the new standard encompasses an enhanced set of diagnostic tools.
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