Research and simulation of FTTX - 2 . optical access network


1.1 At the end of the program

This chapter gives an overview of the birth and development of FTTx network in the world and in Vietnam as well as practical applications of FTTx network.

1.2 The origin of the FTTx network _ _ _ _ _ _

More and more broadband access services are born, but the bandwidth of these types of services is very large. Table 1.1 shows the bandwidth requirements for some of these types of services.

Table 0.1 Bandwidth requirements for some types of services


Bandwidth (downstream)

Broadcast TV (MPEG 2)

2 - 6 Mbps


6 - 12 Mbps

High speed internet

3 - 10 Mbps

Video Conferencing

300 - 570 Kbps

Voice/Video Telephony

64 - 570 Kbps


2 - 6 Mbps

Maybe you are interested!

As of September 2008, the number of broadband subscribers in our country exceeded 1.8 million subscribers. Compared to 2007 the number of subscribers increased by about 50%. The slow growth rate is partly due to the impact of the economic recession. In the following years, the growth rate will be similar and even faster because the economy is stable and developed.

The chart Figure 1.1 below shows the growth rate of Internet subscribers in Vietnam from 2008 to 2012. Through this chart, it can be seen that the market share of the broadband Internet market will gradually increase compared to that of the Internet. overall Internet market share and will reach a maximum of 10% market share by 2012.

figure 1.1 internet growth forecast in vietnam (source cmc telecom) the growth rate of the number 1

Figure 1.1 Internet growth forecast in Vietnam (source CMC Telecom)

The growth rate of the number of Internet users, as well as the number of converted subscribers in Vietnam, is gradually stabilizing at 10 - 30%. The number of people is increasing due to the impact of integration, development and the impact of technology with the goal of creating more and more favorable conditions for users with increasing speed. Part of that development is the transition of Internet users from old technology (dial up) to new technologies (especially ADSL). The proof is that the subscriber growth rate is quite stable at about 30%/year, but the growth rate of broadband subscribers over the past few years has always been over 200% per year.

The international connection capacity of ISPs has increased rapidly over the years, at over 90% per year, which proves the increasing demand for both quality and quantity of Internet users. Vietnam's backbone Internet is usually designed with 3 Internet ports located in 3 regions, with undersea cable system and underground cable system, running rings to backup each other when there is a problem and mainly still connect to 3 points. Japan, Hong Kong and Singapore mainly through the undersea fiber optic cable system. There are feeder connections through VNNIC and peering between ISPs to take advantage of domestic transmission and traffic.

Obviously, with the urgent requirements of the Vietnamese telecommunications market, ISPs are trying to strengthen their network telecommunications infrastructure to meet that demand. On such network infrastructure, there are many access technologies. Technologies in access networks can be divided into two main groups:

Wired technologies:

xDSL (Digital Subscriber Line): ADSL, HDSL, VDSL.. over copper cable.

FTTx: (FTTH, FTTB, FTTC, FTTN..) broadband access over cable


Access to broadband over power lines (Broadband over Power Line - BPL or Power Line Communications - PLC).

Wireless access technologies:

Satellite access.

Local Multipoint Distribution System (LMDS )

WiFi, WiMAX.


xDSL technology: taking advantage of the existing copper telephone cable infrastructure to transmit data at high speed, xDSL splits the bandwidth on the phone line into two: a small part is for voice transmission, the majority is for voice transmission. for data transmission at high speed. xDSL has many variants such as ADSL (Asymetric DSL), ADSL2, ADSL2+, VDSL (Very high bit-rate DSL), HDSL..

Cable TV: High-speed Internet access via cable television is a hybrid model of HFC (Hybrid Fiber Coaxial), taking advantage of the fiber optic and coaxial cable infrastructure of the cable TV network, allowing Internet connection. with maximum download speed up to 10Mbps and upload speed up to 2Mbps much higher than ADSL line speed (8 Mbps download, 600 Kbps upload). Traditional CATV cable networks only transmit one-way information from program content providers (TV channels) to subscribers. In order to use the Internet - a type of two-way communication, cable TV providers need to invest in upgrading equipment to be able to use the Internet.

the ability to transmit information in the opposite direction from the customer end. Also requires connections to the Internet via third-party service providers. This is a disadvantage of this option because of the high cost of implementation, maintenance and maintenance.

WiFi: is a wireless local area network (WLAN) technology based on IEEE standards

802.11. WiFi has been and is being used very widely in public places. However, Wifi is not suitable as an access technology of service providers because the coverage distance is too short (under 100m). With Wi-Fi technology, terminals access the access point (Access point) on a random basis. Therefore, stations far away from the access point are more susceptible to disconnection than stations near. This limits the deployment of high-quality services such as IPTV, VoIP...

WiMAX: is a broadband wireless access technology developed by the WiMAX Forum (WiMAX Forum) and aimed at providing services from fixed to mobile, it allows wireless broadband access to end-to-end (WiMAX). last mile) as an alternative to cable and DSL, especially useful in areas where DSL technology cannot be deployed. WiMAX can provide speeds of tens of Mbps to users and over a distance of tens of kilometers according to IEEE 802.16, the range can be up to 50 km for fixed stations, and 5 - 15 km for mobile.

Although WiMAX has many such advantages and can compete with xDSL, it is not enough to meet the needs of Gigabit-sized bandwidth to users. The implementation of this technology also has certain difficulties. On the other hand, the price of terminal equipment is still expensive, the frequency band used by WiMAX is not compatible in all countries. On the other hand, a limited bandwidth fund can only be granted to certain operators. In addition, WiMAX uses radio waves, so it is heavily influenced by environmental factors.

To meet the urgent needs of the telecommunications market in terms of speed,

type of service… , people think of a new access technology FTTx.

1.3 Definitions _

FTTx (Fiber To The x) is a network architecture in which fiber is pulled from service provider switches to subscribers. In it, optical fiber may or may not be used in all connections from the supplier to the customer. “x” is understood as a symbol representing different types of networks such as FTTH, FTTC, FTTB, FTTN... Therefore, it can replace the current copper cable infrastructure such as telephone wires, cables. Coaxial. This is a relatively new network architecture and is evolving rapidly by providing greater bandwidth to users. Currently, fiber optic technology can provide a balanced transmission rate of up to 100 Mbps.

1.4 I 'm sorry

1.4.1 Classification according to the length of fiber optic cable

figure 1.2 classification of fttx networks by fiber length in general, we can clearly see the 2

Figure 1.2 Classification of FTTx networks by fiber length

In general, we can clearly see the classification of FTTx network system through Figure 1.2 . As in the definition we have types of FTTH, FTTB, FTTC, FTTN... The difference between these types is due to the length of fiber optic cable from the ISP's terminal (OLT) to the users. If from OLT to ONU (user-side terminal) is completely fiber optic cable, it is called FTTH/FTTB.

FTTH (Fiber To The Home): fiber optic cable runs to the subscriber's house.

FTTB (Fiber To The Building): same as FTTH but here it is pulled to the

tall building.

FTTC (Fiber To The Curb): fiber optic cable to a residential area. At that time, from ONU to subscriber can use copper cable. In this model, the user-side terminals are arranged in the cabins on the street, the wires connecting to the subscribers are still copper cables. FTTC allows sharing the cost of an ONU to several subscribers so it can lower the initial installation cost.

There are also some other types such as FTTE (Fiber To The Exchange),

FTTN (Fiber To The Node)…

1.4.2 Classification according to configuration

Point to Point configuration: is a point-to-point connection, there is a direct connection from the service provider to the customer, each fiber will connect to only one customer, so the network configuration is relatively simple at the same time. Because the bandwidth is not shared, the transmission speed can be very high. The transmission process on P2P structure is also very secure because the whole process is done on only one physical line, only the terminals are transmitting and receiving data, not mixed with other customers. However, this structure is difficult to develop for a large scale because the investment cost for one customer is very high, the system will become very cumbersome, difficult to operate and maintain when the number of customers increases. go up.

Point to Multipoints configuration: point-to-multipoint connection, one service provider connection to multiple customers via splitter. In this system, each optical path from a shared service provider is shared by a number of customers. There will be an optical path going to a group of customers that are geographically close together, where this shared optical path will be split into separate optical paths going to each customer. This reduces the cost of installing fiber optic lines and prevents the system from growing cumbersome.

1.5 Prioritize the FTTx network _ _ _ _

1.5.1 Prefer to go to m

FTTx technology uses optical fiber, so it has many advantages of the system

optics in general.

Large capacity: Optical fibers are capable of transmitting large amounts of information. With current technology on two optical fibers, 60,000 conversations can be transmitted simultaneously. One fiber optic cable (diameter > 2cm) can hold about 200 optical fibers, the transmission capacity is up to 6,000,000 conversations.

Insulation: Fiber optic cables made of suitable dielectrics contain no conductors and can allow complete insulation for many applications. It can eliminate interference caused by ground currents or dangerous situations caused by electrical discharges on communication lines such as lightning or electrical problems.

Security: Optical fiber provides a high level of information security. An optical fiber cannot be extracted for information theft by conventional electrical means such as surface conduction or electromagnetic induction, and it is difficult to extract information in the form of optical signals.

High reliability and ease of maintenance: Due to the lack of fading effects and the long service life, maintenance requirements for optical systems are less than for other systems.

Flexibility: Optical communication systems are available for most forms of data, voice, and video communications. These systems can all be compatible with RS.232, RS422, V.35, Ethernet, E1/T1, E2/T2, E3/T3, SONET/SDH, 2/4 wire voice standards.

Scalability: Properly designed fiber optic systems can be easily expanded as needed. A system for low data rates, e.g. E1/T1 (2,048 Mbps/1,544 Mbps) can be upgraded to a higher data rate system by changing the electronics. The fiber optic cable system can remain the same.

Signal reproduction: Today's technology allows fiber optic communication lines over 70 km long before signal regeneration is needed, this distance can be increased to 150 km by the use of amplifiers. great laser.

In addition to the above advantages of optical fiber in general, FTTx technology also has some other advantages. With FTTH technology, service providers can deliver download speeds of up to 10 Gbps, 200 times faster than ADSL 2+. The transmission speed with ADSL is unbalanced, with the upload speed always being lower than the download speed. And FTTH allows balance, upload and download speeds are the same and allows a maximum of 10 Gbps, which can serve hundreds of computers at the same time. Minimum committed Internet speed of FTTx ≥ 256 Kbps.

Table 1.2 Comparison between FTTx and ADSL

Comparative factor



Communication environment


Copper Cable

Optical fiber


susceptible to electromagnetic attenuation,

weather, cable length…



Low security, easy to steal road signals


High security, impossible

Steal the signal on the transmission

Transmission speed

(Upload and download)


Download > Upload

Maximum speed is 20 Mbps

Allow balance:

Upload = download

The maximum speed is 10 Gbps

Comparative factor



Availability of broadband services: Hosting private server, VPN, association


Not suitable for speed


Very suitable because the speed is very high and the speed can be customized.

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