When and where to deploy FTTx

FTTx is a hot topic recently discussed by global operators. However, what is the best policy for deploying FTTx? Optical fiber to the node FTTN), optical fiber to the roadside FTTC) or optical fiber to the building FTTP )? What are the benefits of fiber laying at different locations? Is there an evolution plan that allows operators to gradually bring Optical Fiber closer to users and make full use of a large number of existing copper cables?

The ultimate goal of a carrier is to provide users with new broadband services that are better than other competitors. To implement FTTx, there are two necessary conditions for access networks. First, you must have the user's dedicated bandwidth. In addition, you must have a flexible enough network structure to quickly and conveniently introduce and manage new businesses.

This article focuses on various ways to increase bandwidth on existing networks.

Existing Network

Fiber-to-the-home is a feasible solution that provides the required bandwidth for new businesses. However, for existing networks, fiber laying is much more complicated. The pipeline for trench laying is too costly, and a large number of copper cables already laid are wasted.

Therefore, it is very expensive to build a fiber-to-user network in such a residential area by means of Trenching, drilling holes, or even laying Optical Fibers with small excavators. The closer it is to the user side, the more difficult it is because of the problems related to rights and private property of users. Therefore, it is very difficult to select the most economical and practical optical fiber laying solution in these established residential areas.

Structure of the outdoor Network 

Currently, the existing access network cables are divided into three parts: the feeder cable, the wiring cable, and the incoming cable ). Each part of the cable is connected through a cable bin with a jumper. Generally, the feeder cable contains a large number of copper cables buried in underground pipelines and connected from the local terminal. The binning box connecting the feeder cable and the wiring cable is called the "junction box ". Each transfer box is used by 300 to 600 users.

Screen. width-333) this. width = screen. width-333 ">

User network topology.

Each junction box leads to four to six wiring cables. The wiring cable is connected to the incoming cable through the "cable box. Each binning box connects 4 to 12 users. Wiring cables are directly buried. The optical fiber can be laid from the center to three different locations: To the transfer box FTTN), to the distribution box FTTC) or directly to the FTTP ). The closer the optical fiber to the user, the wider the bandwidth the user receives, but the higher the cost. The type of service required by the user determines the bandwidth, and the bandwidth determines where the optical fiber is laid in the access network.

The transmission rate and service type when the optical fiber is laid to different locations are as follows:

◆ FTTP: a new generation of network services, with 100 Mb/s and n channels.

◆ FTTC: multi-channel high-definition TV, which is connected in VDSL2 mode from the roadside distribution box, with 35 Mb/s, three high-definition channels or eight standard channels plus one VOD channel, IP voice service VoIP), high-speed Internet access 5 Mb/s ).

◆ FTTN: for the broadcast and television business, ADSL2 is used for access from the transfer box, 15 Mb/s, 1 high-definition channel or 3 standard channels plus IP voice service VoIP) and 1.2 Mb/s for high-speed Internet access ).

The user's requirements for a variety of businesses promote operators to adopt the solutions most suitable for future development, which can meet both needs and make profits.

Cost of various solutions

Table 1 calculates the cost of the FTTx solution, including optical fiber to the transfer box, to the distribution box, and to the household. Of course, the distribution of users in each residential area is different. This model assumes that there are 384 users in the residential area, and the average topology of North America is distributed. The prerequisite is that each traffic box is connected to four distribution boxes. The FTTN solution assumes that each user has a DSLAM port. The FTTC and FTTP schemes assume that each household in the community has a port, whether or not it has become a user.

Screen. width-333) this. width = screen. width-333 ">

Table 1. Installation costs of FTTN, FTTC, and FTTP Solutions

At the same time, it also compares the use of different types of DSLAM: The Environment subsystem's rack-mounted DSLAM and the addition of fixed outdoor DSLAM without environmental requirements. The analysis results show that the cost increases significantly from FTTN to FTTC to FTTP. Next, it is very important to judge the ability of various solutions to increase revenue.

FTTN solution: FTTN is the solution with the smallest proportion of optical fiber used in FTTx. Because trunk optical fiber provides a large transmission capacity, you can make full use of existing copper cables.

FTTN is a short-term method for implementing high-profit IPTV services. It not only increases revenue but also reduces customer loss. Moreover, the investment risk of FTTN is minimal, because the DSLAM system can be easily expanded to meet the growth of subscribers and business needs. FTTN devices can be relocated, and optical fiber can be reused in later FTTC and FTTP systems.

FTTC solution: FTTC is an ideal solution that provides high-quality services in a short period of time and can hold a place in the future market. It is a reasonable expansion solution for optical networks, and enables each DSL user to make full use of its bandwidth.

Not every roadside distribution box is used to increase bandwidth. Network planners can decide where to use the distribution boxes to achieve optimal configuration. Of course, it is usually necessary to balance the cost of The binning box resizing and the benefits of the shorter path.

FTTP solution: FTTP is divided into two solutions: Passive Optical Network PON and Active Optical Network (AON. In the AON, a 100 Mbit/s Optical convergence device is installed in the binning box to the gibit Ethernet. There are electrical devices in the AON junction box, while in the PON, the optical splitter and junction are used. An AON device with 100 Mb/s or higher performance can achieve the same average time-free MTBF as a PON device). The advantage of AON is greater, and fan-out fiber is simpler.

Feasible development plan

FTTx's various solutions are mutually incompatible. There is no investment risk for FTTN and FTTC, because the operator can continue to use feeder optical fiber when deploying FTTP in the future. At the same time, these two solutions can make full use of the existing copper access network and provide sufficient loop capacity to provide services that FTTP can provide earlier than FTTP. To immediately obtain revenue and raise funds for the final target FTTP, operators can use FTTN and FTTC as transitional solutions to reduce the threat of cable TV providers.

1. FTTX Optical Network Technology and Its Application
2. Topic: FTTx optical fiber access