ADSL2 + becomes a two-handed PON is a real life?

At the beginning of the year, China Telecom accelerated the news of the existing broadband access network, so that the broadband access market that has been quiet for a period of time has been excited for a long time. After large-scale upgrade of DSLAM equipment, China Telecom has achieved ADSL2 + network access in 26 provinces nationwide, and the bandwidth access speed has reached three times that of traditional ADSL.

The industry generally believes that this upgrade is an emergency action for China Telecom to cope with the huge network bandwidth pressure brought by the video services such as IPTV. As users demand more and more urgent needs for network access speed, service quality, and business security, broadband access technology requires a thorough innovation.

DSLAM device replaced with millions of lines

In this upgrade, China Telecom adopted the ADSL2 + technology, which not only upgraded the original kbps and 2 mbps bandwidth of ADSL to 6 Mbps ~ 8 Mbps. More importantly, its architecture is similar to that of ADSL, and it can be smoothly upgraded. "Currently, most of the DSLAM devices on the market support mixed plug-in between ADSL and ADSL2 +, and the operator only needs to upgrade the software. For some older DSLAM devices, you must switch back to the network ." Zhang Yanfen from Guangdong Research Institute of China Telecom told reporters. Guangdong is the first place where ADSL technology is emerging. It is also one of the first key provinces in China Telecom to launch ADSL2 +.

However, the old devices that need to be removed from the network also caused a huge shock in the DSLAM market. At present, Shanghai Bell Alcatel and Huawei have respectively announced that they have obtained millions of online orders for the project. "This is just the beginning. The upgrade and transformation work will continue to be rolled out, and the capacity of the DSLAM market will grow exponentially ." A device manufacturer's sales staff told reporters.

In fact, DSLAM is already a very mature device in the operator's access network, and its price per port is also decreasing year by year. However, many people have different opinions on China Telecom's large-scale purchase of new DSLAM devices. Wang Yaohua, Senior Manager of infinitus marketing department, believes that ADSL2 + is not suitable for the final bearer Technology of video services. VDSL2 has better QoS characteristics and is a better choice for triple play applications. However, will such a large-scale purchase affect the next bandwidth upgrade at hand?

ADSL2 + is just a transitional

"ADSL2 + technology provides users with higher bandwidth and lower line requirements. It also has many new features and features, this includes data rate improvement, rate adaptability, and fault diagnosis. It will further improve network performance and collaborative work capabilities, and add support for new applications, services, and special purposes. In particular, the bearer of video services that require high bandwidth and service quality will be the advantage of ADSL2 + technology ." Hu Hao of China Netcom Research Institute is obviously a supporter of ADSL2 +.

Compared with technologies with higher transmission rates such as VDSL and SHDSL, the main architecture of the ADSL2 + standard has been basically stable and is basically compatible with the ADSL technology. This is the advantage of ADSL2 +. However, ADSL2 + is only a transitional ADSL strategy, and the bandwidth increase is limited. "ADSL2 + has enabled the transmission rate to more than 2 Mbps, but if HD programs need to be transmitted, the speed will increase to 6 Mbps ~ 8 Mbps. If you provide other services such as Visual phones and 3D games, your needs will exceed 20 Gbps ." This is not a view of the future, but is likely to happen next year.

Who will govern the future?

At present, fixed network broadband access technology is mainly divided into Copper Twisted Pair wires, copper five lines, hybrid fiber coaxial (HFCs) and Passive Optical Network (PON) four types.

Who will lead the future of broadband access technology? At present, there are mature development prospects.

Broadband Access Technology Using Copper Twisted Pair wires (telephone lines) as transmission media is still the mainstream of operators, which mainly includes HDSL, ADSL, VDSL and other technologies. Their advantage is to make full use of the original telephone line resources, but they are obviously at a disadvantage in bandwidth, QoS and manageability.

In order to adapt to the Construction of broadband information-based residential communities, a computer LAN (FTTB + LAN) is used to access users based on optical fiber cables to the building ), fiber + Class 5 Ethernet Switching technology is widely used in enterprise networks. This solution is mainly used to solve the problem that the user is too slow to access the Internet, and provides multimedia services formed by IP technology.

However, its lack of support for traditional voice services is a major drawback of its development.

It is a widely used Access Technology for radio and television. It can provide CATV, voice, data, and other interactive services in a unified manner. However, the original CATV network only provides broadcast services, most of which are unidirectional networks. To achieve bidirectional communication, two-way distribution amplifiers, two-way filters, and two-way trunk amplifiers are required; in addition, a coaxial network can connect up to 500 users, resulting in poor network scalability. This is also a major difficulty for radio and television departments to carry out interactive TV.

According to the latest GPON standard published by the International Telecommunication Union (ITU), the bandwidth download speed reaches 2.4 Gbps, And the upload speed reaches 1.2 Gbps, greatly alleviating the bandwidth pressure on the access network. On the other hand, the commercial use of GPON is also increasing. In the light speed project of bell in southwest America, the Access Mode Based on GPON + VDSL allows the bandwidth to easily reach 20 M, this laid the foundation for developing richer video services. In addition, GPON penetration rates in Japan and South Korea reached 50% or more. Zhang xuping's opinion of Zhejiang Post and Telecommunications Planning and Design Institute represents a consensus in the industry: PON has become the most promising solution for the development of access networks. PON is a revolution in broadband access networks. With the gradual decline in network deployment costs, it will be the best choice for broadband access in the future.

Link: Three highlights of ADSL2 + Transition Period

Despite the bright future of PON in the broadband access field, the ADSL2 +, as a transitional technology, is still widely welcomed by carriers and has played a significant role in many recent network reform projects. The current network situation provides opportunities for ADSL2 +, and its three highlights cannot be underestimated:

First, ADSL2 + has better performance than the first-generation ADSL in terms of speed and coverage. The ADSL2 downstream speed reaches 12 Mbit/s, and the upstream speed reaches 1 Mbit/s. The ADSL2 + standard doubles the ADSL2 Downlink frequency, which greatly improves the ADSL2 + downlink speed within 1.5 kilometers, and can reach more than 20 Mbit/s. Compared with the first-generation ADSL, ADSL2 will provide 50 Kbit/s more speed increments than the first-generation ADSL on the upstream and downstream lines over long-distance telephone lines. At the same rate, ADSL2 increases the transmission distance by about 180 meters, that is, it increases the coverage by 6%.

Second, the use of ADSL2 + can effectively reduce crosstalk interference. When ADSL2 + is used together with ADSL, in order to avoid line-to-line interference, you can set its downstream operating frequency band between 1 MHz and 2 MHz to avoid interference with the downstream bandwidth of ADSL, to reduce crosstalk and improve service quality.

In addition to the above features, the new-generation ADSL technology provides powerful line Diagnostic Technology, enhanced power management technology, rate adaptive technology, multiline bundling technology, channelized technology, and other improved technologies, this makes the new generation of ADSL technology advantageous in carrying video services.

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