Large bandwidths are the key to applications such as IPTV, video streaming or other cloud services. These can be guaranteed by using fibre optic cable or G.fast technology, which enables large bandwidths even with traditional copper cables. The technical solution also depends on the building’s structure. With its MileGate series, our partner DZS offers suitable products for many scenarios.
Fibre optic is the premium broadband technology. Fibre optics are characterised by low losses (enabling greater distances) and relatively good resistance to electromagnetic interference (interference due to machines, switches, lightning, transmitters) and light. But fibre optics are not yet available everywhere. Generally, network operators use different combinations of copper cables and fibre optics.
The bandwidth depends upon how far the fibre optic cable is from the end customer. Variants are Fibre To The Curb (FTTC), Fibre To The Building (FTTB) or Fibre To The Home (FTTH). The following rule of thumb applies: the closer the fibre optic cable is to your home, the higher the data rate.
Single family dwellings are often connected directly via two to four fibre optic cables. Here a bandwidth of 1 GBit/s is guaranteed up to the receiver in the POP (Point of Presence), using conventional routers. POPs are the nodes at which the individual fibre optic strands are bundled together, or where there is a transition to another provider.
DSLAM for apartment blocks
The situation is somewhat different in apartment blocks. There, connections are primarily FTTB, where the fibre optic cable extends into the cellar of a building. From there it usually proceeds to the end customers’ connections in the individual apartments via slower copper cables (= local loop or “last mile”). This is generally achieved using a DSLAM in the building’s plant room.
DSLAM stands for Digital Subscriber Line Access Multiplexer. The unit collects and terminates the incoming VDSL subscriber lines from the cable splitter (FTTC) and routes the data traffic via a fibre optic broadband interface into the operator’s network. As part of its MileGate series, DZS offers a variety of DSLAMs for VDSL2 or the rapid G.fast technology.
VDSL2 enables data rates of more than 300 MBit/s to be achieved, but only if the cables are short and there are few VDSL2 subscribers in the cable. In practice, crosstalk (FEXT, Far-End-Crosstalk) between the individual VDSL2 signals on the copper cables is partly responsible for the theoretical data rates not being achieved. Vectoring is the solution here, since this almost completely compensates crosstalk on the cable and significantly increases the actual bandwidth.
The compact DSLAM IP-MSAN MileGate enables up to 960 VDSL2 ports enhanced with vectoring per 8 RU subrack. This means that data rates of more than 300 MBit/s can be achieved in the downstream direction and more than 50 MBit/s in the upstream direction.
Data highway with G.fast
One option for a faster connection for the “last mile” is G.fast technology. G.fast has been standardised by the ITU (International Telecommunication Union) (ITU-T G.9701) and stands for “Fast Access to Subscriber Terminals”. Theoretically, a data rate of 2 GBit/s is possible. Realistically, a bandwidth of between 600 and 1,500 MBit/s can be assumed. G.fast achieves this bandwidth using vectoring, high frequencies for data transmission, a new error correction method and bundling of upstream and downstream traffic.
G.fast is comparable to DSL, but uses significantly higher frequencies for data transmission. Whereas VDSL2 uses frequencies of up to 35 MHz, with G.fast the frequencies are up to 106 MHz for the first phase, and up to 212 MHz for the second generation. Of course, as more bits can be transferred in a broader frequency band, the bandwidth and data transfer speed also increase. However, with high frequencies in unshielded cables, the risk of interferences such as crosstalk or from electromagnetic influences such as electrical equipment also increases considerably. The quality and length of the house/apartment cabling also affects the bandwidth actually achieved. G.fast can generally achieve optimum performance up to cable lengths of 50 m.
The G-fast DSLAMs from DZS offer G.fast 212MHz with 4, 8, 16 or 24 ports for flexible installation in apartment buildings. New models such as the MileGate 205x series also offer features such as reverse power feed and MELT. You can find a product overview here.
FTTH solutions: fibre optic all the way into the home
With the access switches MileGate 2200, 2310 and 2510, DZS also offers solutions for apartment blocks where the apartments are already connected via fibre optics (FTTH). These devices, also named MSAN (Multi Service Access Node), are essentially DSLAMs with additional options. The network operator is not only able to connect all DSL variants (ADSL2plus, VDLS2 with vectoring, SHDSL EFM/TDM), but also Ethernet, analogue and ISDN telephony.
One explicit solution for building FTTH/B networks is the MileGate Fibre Series from DZS. The target customers are network operators who wish to set up flexible fibre optic networks for private households and enterprises. The units are great value for money thanks to the extremely high port density – with up to 480 fibre optic connections in P2P networks and up to 160 GPON ports in PON networks. PON stands for Passive Optical Network and enables point-to-point and point-to-multipoint architectures. P2P-FTTH networks are point-to-point network structures where each subscriber receives their “own” fibre optic cable.