Three-network convergence access network using EPON technology

1 Introduction

With the State Council's approval of the three-network integration policy, the wave of cable network evolution to the next-generation broadcast television network ( NGB ) has become unstoppable, and NGB's backbone network and content platform have already had relatively mature solutions, access The construction of the network has become the focus and difficulty of the current NGB construction due to the complexity of the solution and the importance of the proportion of the overall investment.

2 Access network technical solutions

Due to its high bandwidth, easy maintenance, and long-distance coverage, EPON technology has become the mainstream bearer technology of FTTx. Currently, the industry chain is well-developed, and it is the preferred technology for telecommunications operators to build access networks. However, due to the high cost of using fiber-optic direct-to-home at the resident network level, traditional telecom operators have basically adopted the FTTB + LAN or FTTB + DSL solution, which has obtained the best Network performance.

Broadcasting and television operators have long focused on the construction of HFC networks and have a huge HFC access network. Using HFC as a medium for household entry can achieve maximum practicality and economy. The coaxial cable network in the radio and television HFC network is an ideal data transmission medium, especially in the last 100m of the bandwidth support capability is much higher than Category 5 line or telephone line resources. Therefore, how to integrate optical fiber and HFC two-way media in the two-way transformation of the broadcast and television network, and to deeply explore the value of the existing network has attracted the attention of broadcast and television operators. There are currently three economically feasible two-way transformation technical solutions: CMTS, EPON + LAN and EPON + EoC.

(1) CMTS is suitable for sparse mode network coverage area

CMTS utilizes the existing cable TV network to perform bidirectional transmission on the low-frequency end of HFC by QPSK / QAM modulation of the signal. The advantage of CMTS is that the technology is relatively mature, the network management capability is strong, and large-scale two-way coverage can be achieved. The disadvantage is that the noise convergence effect of CMTS affects the bandwidth and performance of the system. The quality requirements of coaxial cables and connectors are high, and the subsequent maintenance workload is large. For most cable operators, upstream noise is a common problem, especially It is in the low frequency band. The CMTS equipment has weak packet forwarding capabilities and cannot meet the increasing demand for high-bandwidth services. It can carry limited services and cannot provide full service bearing. The subsequent system expansion cost is huge. Cable access of CMTS belongs to the shared line mode. If it is only used for broadband access and Internet access, it is more suitable for broadcasting and television to develop data services when the number of users is not too large. For the current concentration of domestic users, users need to occupy the network for a long time, and high-throughput data throughput. The unit bandwidth drops significantly, which is not conducive to the development of high-bandwidth services. It is not economical to use CMTS to achieve broadband access for a wide range of users.

(2) EPON + LAN is suitable for high density users to build new communities

The EPON + LAN solution connects to the building through the EPON network, provides the Ethernet interface through the ONU, and the user access is realized through the Ethernet Category 5 cable. Using this solution to achieve user voice and Internet access, cable TV signals are still realized through HFC lines. Its advantages are mature technology, more equipment vendors, interfaces and standard specifications. This solution is suitable for high-density users and large-bandwidth business needs. The first comprehensive wiring of a new community is completed at one time. For the old users who have already opened cable TV, they need to re-wire. The construction of residential corridors and indoor wiring is difficult. Generally unwilling to accept.

(3) EPON + EoC is the preferred technology for existing CATV users

EPON + EoC technology is based on the existing HFC network to construct a digital bandwidth user access network suitable for radio and television network systems. It uses advanced modulation and demodulation technology without affecting the normal operation of the existing CATV. The Ethernet signal is synthesized in the coaxial cable and transmitted together with the original CATV signal, which is used to carry IP-based data, voice and video services. It transforms the original one-way cable TV network into a two-way, two-way broadband network capable of carrying multiple services with less reconstruction cost and engineering volume. The use of EoC technology has good adaptability and flexible networking solutions, making full use of the original coaxial access network resources of radio and television, and saving the line investment of the households.

Combining EPON technology and EoC technology to unify the network management and form an overall solution can provide the best technology for the access network for the development of the NGB integration of the three networks. EPON + EoC can provide three kinds of integrated bearers of data, video and voice, and provide the functions of multiple networks in the past through one access network. In the development process, the program fully considered China's national conditions and the actual situation of the current radio and television network, and used the existing Cable network of the radio and television grid as the transmission medium at the resident network level, saving a lot of comprehensive wiring costs and operation and maintenance investment, and having high performance And low cost. EPON + EoC technology meets the needs of two-way transformation of broadcasting and TV digital TV and the integration of the national three networks. It will promote the in-depth development of the NGB industry in China and is the preferred technology for the NGB network access layer of broadcasting and television operators.

3 EPON and EoC networking technology

(1) EPON technology

Optical fiber, as the best medium for high-speed, large-capacity, and multi-service transmission, has long been widely used in backbone networks and metropolitan area networks. At the access network level, optical fibers have also been popularized and applied. Optical fiber has the advantages of long life, high reliability, and strong anti-interference. Optical transmission has a strong bandwidth expansion capability, and it is easy to achieve the integration of various business platforms.

EPON technology is a technology that combines Ethernet and passive optical network, and can support 1.25Gbit / s symmetric rate according to IEEE802.3ah international standard. As an important solution of the optical fiber access network, EPON technology has unmatched characteristics such as ADSL and LAN, and it also meets the multi-service access requirements of "Everything over IP" more efficiently than APON, BPON, GPON and other technologies. EPON access network has the advantages of low investment cost, simple operation and maintenance, etc. It provides a very cost-effective broadband access solution for operators to solve the "last mile" problem. At present, EPON technology has been widely used at home and abroad, and has been supported and recognized by domestic and foreign operators and manufacturers.