The demand for higher data rates is continuously increasing driven by the applications like Cloud Computing, Big Data and Internet of Things. Meanwhile, the strong market competition makes the network operators to improve the network architecture and deliver high speed services. Pure fiber network should be the best solution. There is no wonder that the fiber network is the trend of the future and it is gradually extended closer to users during the transition from copper-based access networks to pure fiber networks. However, it is not favorable to connect the fiber directly to the customer premises and the cost is high in some cases, like old buildings. To find the fast and cost-effective way to deliver Gigabit speed Ethernet, copper access technology is being applied in some cases. This technology is known as G.fast.
G.fast, based on the latest VDSL technology including cross talk cancellation and re-transmission, is designed for use in a ‘last-mile’ of less than 250 meters. Combining the advantages of fiber optic access technology and copper access technology, G.fast can deliver data at fiber speed to the customers using telephone copper wires.
The problem with G.Fast is that its ultra-fast speeds only work over very short distances. To shorten the copper distance, FTTdp is usually applied with G.fast. “dp” here stands for “distribution point”. This solution brings the fiber optic cable out of street cabinets and moves it closer to home via the distribution point. The following network diagram shows the difference of FTTH and FTTdp using G.fast. The blue lines represent fiber optic cable, the red ones represent copper wire.
It seems that there is no need for copper access in building a FTTx connection. But in practice, connecting the fiber directly to the customer premises causes some disadvantages which can be solved by G.fast.
There might be many difficulties when deploying fibers to the user homes, especially some existing buildings. Sometime it is even not possible to deploy fibers to the user homes. In addition, most in-house telephone installations still rely on copper cables for most existing and newly constructed buildings because fibers are expensive and difficult to handle. There is no need to deploy fiber optic cable in building and home when delivering Gigabit Ethernet with G.fast.
The fiber optic based customers premises equipment (CPE) are usually installed by technician. Compared with fiber optic connections, copper-based CPE installation is simple. Just connecting the CPE to the telephone plug with the delivered cable would finish the installation, which can be installed by customer. Thus, G.fast can save the cost for new users and makes the home installation much easier.
Optical fibers can be broken or have transmission loses when wrapped around curves and optical fibers require more protection around the cable compared to copper. What’s more, the fault location from the CPE is not easy. It would cost more to maintain the fiber connections compared with copper connections achieved by G.fast.
At first glance, G.fast is limiting the transmission from copper to fiber. Actually, G.fast accelerates the deployment of fiber optic networks. It cost a lot of time and money to process the paperwork and get permission of the subscriber before deploying the fiber optic cable. The processing is complicated. Hardware foundation is the main advantages of G.fast which eliminates the need to rewire the whole building and still allows a noteworthy uplift in access speeds. Copper is everywhere in telecommunication network. The hybrid copper/fiber approach—G.fast making full use of the telephone wires in the buildings actually makes the customers closer to optical fibers in time save and cost save manners. In this way, the transmission from copper to fiber is actually being promoted by G.fast.
Weighing time, broadband speed and cost, operators figure out that applying G.fast in FTTH is an economical and time-saving way to bring Gigabit speed Ethernet to the users. To capture market share of broadband service, some network operators are considering to use G.fast. Alcatel-Lucent and communications services company BT have already started a consumer trial of G.fast technology in Gosforth (situated in North-Eastern England), for offering ultra-broadband access to consumers.
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