Where is the access network technology?

There are still many access network technologies worth studying. Today we will introduce some development directions of access network technologies, and compare them with some common access network technologies, I hope it will help you understand this knowledge.

At present, China's telecom industry has undergone earth-shaking changes. Operators are split and merged to form three full-service operators: China Mobile, China Telecom and China Unicom. The changes in operators have directly led to changes in the market structure and competition situation. At present, operators focus on the construction and development of mobile businesses. In the long run, although operators are currently focusing on developing 3G mobile services, the successful operation of the original Telecom and China Netcom in broadband services, new carriers will never miss the development of mobile and broadband data services.

Challenges for carrier networks after restructuring

In recent years, the rapid development of high-speed data services has greatly promoted broadband and IP-based fixed networks. In the development of backbone networks, IP bearer networks with hundreds of GB or even several TB capacity have become a reality. In metro networks, most of the networks have built the 10 Gbit/sSDH ring of DWDM, the Metro extension of the IP bearer network is also under research and development. Network Access is complex and provides a wide range of solutions. Currently, most mainstream technologies include ADSL, Ethernet, EPON, GPON, and wireless access network.

Broadband and IP are the common development trends of mobile businesses and fixed businesses. Backbone Networks and metro networks have basically met the conditions for carrying broadband data services. At present, network bottlenecks are concentrated in the access network section, especially the access network technology of the last kilometer.

Compared with GSM, in addition to narrowband voice, WCDMA supports high-speed data services for mobile networks. Currently, the bandwidth of the empty port can reach 14.4 Mbit/s for a single sector. In commercial use, the base station throughput of S1/1/1 can reach 4 ~ 7 Mbit/s. The increase in air port bandwidth puts forward new requirements for the back-haul of the base station. In a GSM network, a single base station generally requires 1 ~ Two E1 instances. In the WCDMA network, four to four bits are required for a single base station in the S1/1/1 configuration ~ Six E1 instances. More bandwidth is required when multiple carriers are configured.

The requirements of mobile networks for access networks are mainly composed of two parts: Base Station return and indoor coverage distribution system. Currently, most base station backhaul devices are SDH or MSTP, and some use microwave and PDH devices. In the indoor coverage distribution system, because GSM is a non-self-interference system, more than half of the current network uses a wireless direct station, that is, the base station and the direct station are implemented through wireless transmission. In addition, most indoor coverage uses coaxial cables. Because WCDMA is a self-interference system, in order to reduce interference, there will be no large number of direct stations in the indoor distribution system, and the transmission between the source and the original direct station is a problem that must be solved. For fixed networks, the main purpose of the access network is to carry high-speed data services, including basic Internet services, e-commerce, and online games. With the maturity of IPTV technology, access networks must be able to meet the development of IPTV services.

In addition, the convergence of telecommunication networks, the Internet, and the broadcasting and television networks is a direct manifestation of the Integration of access networks. How to meet the coordinated development of mobile and fixed services and adapt to the development trend of the network is a problem that must be faced by integrated operators.

Existing Access Network Technology and Comparison

1. Several mainstream access network technologies

Currently, the mainstream access network technologies include xDSL, Ethernet access network technology, EPON/GEPON, GPON, and WiMAX. XDSL is divided into Asymmetric Digital user line (ADSL) and high-speed digital user line (VDSL ). The ADSL system is a broadband access network technology implemented by copper cables of twisted pair wires. Its biggest feature is that it can provide broadband services without modifying the existing copper network. The VDSL system is an evolving version of ADSL that supports access to TV signals. It is an optional access means to achieve triple play.

Ethernet is a connection technology that allows computers to access local networks. With the development of Fast Ethernet and Gigabit Ethernet technology, it has some advantages in broadband data access. However, more efforts need to be made in QoS Control and telecom level, especially in implementing clock synchronization to meet the existing TDM access requirements.

EPON/GEPON (Ethernet Passive Optical Network/G bit Ethernet Passive Optical Network) is a new type of optical fiber access network technology. EPON/GEPON uses a point-to-multiple-point structure and Passive Optical Fiber Transmission to provide multiple services over Ethernet. It features mature technologies, low maintenance costs, and high speed, however, it is still to be improved to support TDM services.

GPON (Gigabit-CapablePON) technology is based on ITU-TG.984.x standards of the latest generation of broadband light-less integrated access standards, with high bandwidth, high efficiency, large coverage, rich user interfaces and many other advantages, most operators regard it as an ideal technology for broadband and integrated transformation of access network services. WiMAX (WorldInteroperabilityforMicrowave Access) is a broadband wireless MAN Access Technology Based on the IEEE 802.16 standard. WiMAX is highly scalable and secure, has complete standards, and can support multiple businesses, it can also provide telecom-level protection services.

2. Comparison and Analysis

Fixed access technology ADSL, Ethernet, and EPON/GEPON have been widely used. To adapt to the rapid growth of data services, the rate of ADSL needs to be further improved. In addition, although ADSL gradually develops to support video signals, its outbound rate is not high and the overall cost is high, which limits its development. Ethernet technology is simple, but its technology itself is non-Telecom-grade network, and there is still much work to be done in terms of security and service QoS. Compared with ADSL and Traditional Ethernet, EPON/GEPON integrates the advantages of PON and Ethernet technologies: low cost, high bandwidth, and high scalability, and has compatibility with existing Ethernet. With the accelerated development of China's "light-incoming copper" trend, EPON/GEPON has become an important technology of FTTB/FTTC, FTTO and FTTH.

Unlike EPON/GEPON, GPON can map TDM services to GEM Frames Based on standard GEM frames and directly support TDM services. This method has unparalleled advantages in supporting both traditional TDM services and IP data services. At present, due to its mature chip and the high price, the commercial use is limited.

WiMAX based on 802.16d uses many technologies such as OFDM/OFDMA, MIMO, and adaptive coding modulation to meet the requirements of "last mile" access, in addition, some wired resources do not have access or are difficult to access, which has a good substitution effect. However, because there is no frequency resource in China, it is only in the test phase.

PON is the development direction of Broadband Access Network Technology

To meet the coordination and rapid development of the entire business, the restructured operator will pay attention to the construction and transformation of the access network. In most cases, the access network must take into account the control and management of multi-service access while pursuing broadband. That is, the access network must be able to provide telecommunication services. In addition, in order to adapt to the rapid development of data services, access networks must also adapt to the development trend of IP. Of course, technology is not the only factor in the development of access networks. In most cases, in order to save investment and reduce the difficulty and time of construction and transformation, select the most economical and reasonable access network technical solution based on different business needs and different network conditions.

In general, PON (EPON and GPON) technology should be the development direction of broadband access networks, especially with the advancement of triple play, technologies represented by EPON and GPON will be widely used in FTTx. To protect the inherent investment, the operator will constantly upgrade the existing Ethernet Access Network and ADSL to meet the needs of broadband. When the investment recovery reaches the Balance Point, it is gradually replaced by PON technology. In addition, for buildings that are difficult to access with fixed access networks, or locations that have temporary business needs, the broadband fixed wireless access network technology represented by 802.16dWiMAX will be developed as an important supplement to the Wired Access Network Technology of telecom companies.

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