Technology VDSL ( Very high bit-spleen DSL ) is based on same technology as the xDSL, (signals VDSL are transferred onto a pair of copper, simultaneously and without interference with the telephone voice), it makes it possible to reach very high bancs: it can provide of 13 to 55,2 Mbps in a direction and of 1,5 with 6 Mbps in the other or, if one wants to make a symmetrical connection of it, a flow of 34 Mbps.
VDSL in simple network
The VDSL is a technology network, which can be used within a domestic network or in a building.This technology makes it possible to establish connections network to high banc without deploying wiring dédié : it is enough to use existing telephone installations.
It is possible to deploy the VDSL in buildings, hotels, hospitals, etc
In this case, it is necessary to use a case distributer with the root of the phone network, and a case customer (modem VDSL) on the level of each catch of telephone, thus associating a catch RJ45 to him.
For a personal use (house, apartment), it is possible to use the VDSL to connect two distant points, that is to say if the distance exceeds the 100 m maximum of the Ethernet networks, that is to say if the telephone installation is existing, but that the deployment of Ethernet cables poses a problem of cost or feasibility. One calls that a bridge VDSL .
In this case, one uses an installation based on an interface waiter at an end of the telephone wire, and an interface customer at the other end. Each case is connected to an Ethernet network by a connector RJ45. The assembly is invisible for the users, who see the other part of the network as if they were connected there by a traditional Ethernet cable.
For this use, one uses a symmetrical VDSL, with a flow of 5,10,15,18 or 34 Mb/s, according to the distance, which can reach 1,5 km.
Among the manufacturers of interfaces VDSL, one finds Zyxel, MRV, SMC Networks, Allied Telesyn or RAD.
Use for connection with Internet
To reach the maximum flows, the user will have to be with less 300 m of DSLAM. And as of 1 km of distance, it becomes more interesting to use another technology like the ADSL 2+. To use VDSL , one will have to thus carry out FTTN ( Fiber To The Neighborhood ), i.e. to bring fiberoptic to each district, where DSLAM would be established. Into France, that would result in the installation of DSLAM in the under-distributers, which generated many costs of establishment. An interesting and perennial alternative would consist in establishing fiber to the user: FTTH ( Fiber To The Home ).The VDSL is used today mainly in South Korea.
In France, the company Erenis deploys in Paris since the end of 2002 network of which the final part, in the buildings, uses the VDSL. The buildings are connected via fiberoptic and the VDSL makes it possible to propose up to 100 Mbps with the subscriber, at the very short distance in the building. The use of the VDSL allows the re-use of telephone wiring in the residences, with the risk that this one is incompatible with very high banc if it is too old. With at the end of 2006, this network is present in 12 Parisian districts and in Asnières (92) and covers approximately 150.000 residences.
Interferences with the telephones
Like the ADSL, the VDSL must be isolated from the apparatuses of telephony (responders, etc).Often, modem VDSL is used itself as filter, being intercalated between the faceplate and the phone network.
If there exist other telephone peripherals on the line, they should be insulated by a filter VDSL. In practice, a Filtre ADSL makes the deal very well.
VDSL2
VDSL2 is the successor of the VDSL. Among the notable improvements, speed passes to 100 Mbit/s in full-duplex, and outdistances it between the user and the DSLAM is carried to 3 500 meters.Whereas technologies VDSL2 seem forsaken in France with the profit of fiberoptic, the majority of the European operators announced deployment VDSL2 with large scales. Indeed this technology allows flows of 50 Mbits symmetrical for investments 10 times lower than fiber, in particular in suburban zone. Indeed in the suburban zones (50% of the habitat in France) which refuse the overhead cables the cost of civil engineering makes the VDSL2 incomparably more effective than fiber.
The VDSL2 remains an interesting technology.
The VDSL2 is a standardized technology (ITU G.993.2) and rather effective: it makes it possible to obtain a band-width of 100 megabits to 500 meters on a simple pair of copper cables (into symmetrical), like that used currently with the ADSL (250 megabits with the source). Much country, whose Finland, Belgium or Germany (for example) intend to deploy VDSL2 in a commercial way. In France, even if tests were carried out, it seems that the fiberoptic (in FTTH) is preferred. The advantage of the VDSL2, it is obviously the cost: it “is enough” to draw fiber to a terminal (placed for example at the beginning of street) and the users are then connected with the traditional network to the latter, which avoids placing fiberoptic in the dwellings, in particular.
As effective as the ADSL at the long distances The VDSL2 is very fast in lower part of 500 meters, and with the top technology remains equivalent to the adsl2. Starting from 1,6 km, the VDSL2 is besides equivalent to the ADSL2+ on the level of the performances.
The only difficulty of deployment is related to cross talk with the ADSL: one cannot mix the ADSL and the VDSL on cables dividing the same sheath.
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