ADSL line extender: an effective means to eliminate IPTV bandwidth bottlenecks

I. Introduction to IPTV:

IPTV, also known as network TV and broadband TV, is a service that uses the broadband network to provide interactive multimedia services for users. IPTV is the result of the convergence of the Internet and traditional TVs. Video Streams are broadcast to IP networks after efficient compression and encoding, you can use IPTV devices at the edge of the broadband network to transmit IPTV services such as live TV, on-demand video, and personal video to users. It can also configure multiple multimedia service functions based on the user's choice, it includes digital TV programs, visual IP phones, DVD/VCD playback, Internet tours, e-mails, and a variety of online information consulting, entertainment, education, and business functions.

With the continuous development of broadband, TV services provided through the high-speed internet are becoming a reality. IPTV carriers can inject TV content into broadband networks, integrate cable TV resources on the broadband platform, give users more choices, and make full use of broadband resources to further increase the user's APRU value.

Ii. Bandwidth bottleneck of IPTV applications

IPTV can use existing copper resources to transmit interactive TV programs. At present, most broadband users in China use ADSL as the access method. However, using the ADSL Access Mode to watch IPTV faces the following two challenges:

1. distance problem: the user line ring resistance suitable for activating ADSL service should be less than 900 ohm, and the line length should be less than 3.7 kilometers.

The longer the line distance from the local device DSLAM to the client device, the greater the attenuation, which will directly lead to a decline in the rate of the ADSL line, an increase in the bit error rate, or even a "disconnection" or no activation at all.

2. speed problem: to achieve stable online IPTV watching, generally the downlink bandwidth speed must be above the K user side. The theoretical ADSL speed must be at 2 M (Center side) above. Therefore, it is difficult for common ADSL users to watch IPTV online with high quality.

Iii. How to eliminate bandwidth bottlenecks of IPTV

To extend the coverage distance of ADSL, increase the user-side rate, and provide a network platform for streaming media applications, a solution is urgently needed to solve this problem.

The ADSL line extender developed by Chengdu Wide Area Communication Technology Co., Ltd. in China can solve the above two problems. When used in the first-generation ADSL system, the transmission distance from the general center to the client is 3.5Km (4mm-5.5 twisted pair wires) while maintaining the normal telephone service ~ 6Km (4mm. Twisted Pair wires). When used in the ADSL2 + system, the coverage distance of the central bureau can be expanded to 6 ~ 7.5Km (4mm. Twisted Pair wires ). Ensure that the user-side uplink/downlink speed is 128 kbps/512 kbps within the extended range.

The typical application of the ADSL line extender is as follows:

Figure 1 application with POTS signal requirements

ADSL

In Figure 1, L1 and L2 are signal cables, while L3 is remote supply cables. When local power supply is not available for the ADSL line extender, the power supply of the ADSL line extender provides power for the ADSL line extender. The power supply of the ADSL line extender can be placed in the local data center or on the user end, in this case, the remote supply line must provide the remote power supply for the ADSL line extender to L3. If there is a stable power supply in the place where the ADSL line extender is located, local power supply can be used.

Figure 2 applications without POTS signal requirements

In Figure 2, L1 and L2 are signal cables. When local power supply is not available for the ADSL line extender, the power supply for the ADSL line extender is provided. In this case, the power supply is placed in the local data center. Because L1 does not have a POTS signal, the power supply can use L1 to provide a remote power supply for the ADSL line extender.

To solve problems such as crosstalk and network management in ADSL applications, the ADSL2 + technology has entered the practical stage, enabling ADSL users to have a longer distance and a higher speed, and more powerful network management functions. However, the DSLAM coverage distance of ADSL2 + is still limited. It still needs to be used with the ADSL line extender to cover more broadband users and improve the access rate of the user end.

Figure 3 shows the performance comparison before and after using the ADSL line extender in the ADSL system:

 

Figure 3 comparison before and after application of ADSL line Extender

The following conclusions can be drawn:

«The ADSL line extender can help the operator solve the problem that it cannot be 3.5 kilometers away from the Central Bureau ~ Difficulties for users within 7 kilometers to provide ADSL Services;

«For users within the ADSL Access range, the Internet access rate can be greatly improved when the local device of ADSL is released.

Statistics show that the distance between 10% and 20% of common ADSL users cannot be met. For 3.5 ~ With the application of the ADSL line extender, a 7Km (4mm. 3.5 twisted pair wire)-distance loop can quickly build a km-long loop in the suburbs ~ Users 7 km long can provide satisfactory broadband services, successfully solve the problem of remote ADSL Network coverage, and can also improve the quality of broadband service in the network edge areas, provide users with more comprehensive ADSL Services, including IPTV services.