EPON convergence access network technology based on

The development of information society makes more and more people cannot do without the network technology provides convenient, after the rapid development in recent 20 years, China's telecommunications networks, cableTV networks and the Internet have become the first in the world. At present, China's cable TV network has 3330000 km cable lines, 10000000 km coaxial cable, cable TV subscribers reached 175000000 households, of which65000000 TV digital signal, analog TV users more than 100000000 households, the cable TV network to providebroadband Internet users about 3000000 households. In 2009, the infrastructure telecommunications enterpriseInternet broadband access net increase of 20347000 households, 103226000 households, the number of broadband Internet users reached 346000000. By contrast, maximizing the use of existing cyber source, two-way transformation with small investment, rapid development of broadband users, radio and television industry is facing a great challenge and opportunity.

With the State Council for approval policy convergence, forward cable TV network evolution as the next generation of broadcast television network (NGB) tide is irresistible, backbone network and the content of NGB platform have been relatively mature solution, construction of access network and become the focus and difficulty in theconstruction of NGB because of the complexity of the solution and the importance of overall investment ratio.

The 2 access network technology

EPON technology due to the high bandwidth, easy maintenance, long distance coverage characteristics become the mainstream of the current FTTx bearing technology, the development of industry chain perfect, is the preferred technique for construction of telecom operators access network. But due to the customer premises network levelusing optical fiber directly to the high cost of users, the traditional telecom operators basically uses FTTB+LAN orFTTBDSL scheme, in this premise to save customer premises network investment, obtain the best network performance.

The construction of radio and television operators have long focused on the HFC network, HFC access network withlarge, using HFC as a home media can realize the practical and economic maximum. Coaxial cable network and HFC network is a kind of ideal data transmission medium, especially in the last 100m of bandwidth to support capacity is far higher than the five lines or telephone line resource. Therefore, how to integrate the two kinds of dielectric fiberand HFC in CATV Network Bidirectional Transformation, in-depth excavation of the existing network value, by radio and television operators are concerned. There are currently 3 bidirectional transformation technology feasible:CMTS, EPON+LAN and EPON+EoC.

(1) CMTS for sparse mode network coverage area

CMTS use of cable TV network existing, through the signal modulation QPSK/QAM, two-way transmission of low frequency end in HFC. The advantage of CMTS is a more mature technology, management ability, and can realize the large-scale two-way covering. A drawback is that CMTS noise collection effect affect the bandwidth and performance of the system, coaxial cable and connector quality requirements higher, follow-up maintenanceworkload; for most cable TV operators, the uplink noise is a common problem, especially in the low frequency band.CMTS packet forwarding capability is weak, unable to meet the growing demand for high bandwidth services,bearing Services Co., unable to provide full service, follow-up system expansion costs. CMTS Cable access toshared line, if only for broadband access and Internet users, in case of not too many more suitable for radio and television to carry out data service. The current domestic users focus on the living, the user needs long timeoccupies network, large flow throughput data, unit bandwidth decreased obviously, is not conducive to high bandwidth services, using CMTS to achieve a wide range of users of broadband access is not the economy.

(2) the EPON+LAN suitable for high density of users of new residential

EPON+LAN is through the EPON network access to the building, providing Ethernet interface by ONU, user access is realized through the Ethernet five lines. By this method, to achieve the user voice and Internet access, cable TVsignal is realized by HFC line. It has the advantages of mature technology, equipment manufacturers more,interfaces and standards. A complete the programme for the first time the comprehensive wiring in the high densityof users and large bandwidth requirement of new residential, but has opened the old user cable need to re wiring,residential building and home wiring construction difficulty, the user a (3) preferred technology EPON EoC forexisting CATV users

EPONEoC technology is digital bandwidth access network in HFC network based on the existing structure applied to a network system, if it does not affect the existing CATV normal work, the modulation and demodulation technologyadvanced, the Ethernet signal transmission together with original CATV signal in coaxial cable, used to carry IP data,voice and video services based on. It is to transform the cost and the project less the original cable television network transformation way become a two-way, capable of carrying a variety of business two-way broadbandnetwork. Using the technology of EoC has good adaptability and flexible networking solutions, and make full use of the radio access network resources coaxial original, save the home part of the line investment.

The EPON technology and EoC technology combined, unified management, global solutions, to provide the best technology development of the access network for radio and television networks NGB. EPONEoC can provide data,video, voice in one of the three play the comprehensive carrying, past a network function provided by an access network. The scheme to fully consider the actual situation Chinese situation and current radio and television networkin the development process, the customer premises network level using radio and TV network existing Cable networkas the transmission medium, saving the cabling cost lots of investment and operation and maintenance, highperformance and low cost. EPONEoC technology to meet the needs of DTV Bidirectional Transformation andnational integration, will promote the further development of NGB industry in the China, for radio and television operators NGB the network access layer is the preferred technique.

3EPON and EoC networking technology

(1) EPON

The best medium for optical fiber as transmission speed, large capacity, multi service, already obtained the widespread application in the backbone network and metropolitan area network, the levels of access network, optical fiber has also obtained the popularization and application of. Optical fiber has the advantages of long service life,high reliability, strong anti-interference advantages, has the very strong light transmission bandwidth expansionability, and easy to realize the integration of various business platform.

EPON technology is the combination of Ethernet and passive optical network technology, in accordance with the IEEE802.3ah international standards can support 1.25Gbit/s symmetric rate. As an important solution of optical fiber access network, EPON technology has the characteristics of ADSL, LAN and incomparable, are better than those of APON, BPON, GPON technology is more efficient to meet the "multi service access requirements of EverythingoverIP". EPON access network has low investment cost, simple operation and maintenance and other advantages, to solve the "last kilometer" problem provides a very economic and effective broadband accesssolutions for operators. At present, the EPON technology has been widely used at home and abroad, supported and recognized by domestic and foreign operators and manufacturers.

Through the EPON system, using FTTH/FTTB optical fiber network covering family, enterprise user can provide the maximum bandwidth transmission rate up to 1Gbit/s. Operators can use the economic cost and cable little investment, convenient to realize high-speed Internet access, send IPTV multicast / on demand high bandwidth IP data services.

The EPON system is mainly composed of OLT (OpticalLineTerminal, optical line terminal) and ONU(OpticalNetworkUnit, optical network unit) and a separator (Splitter), OLT to IP network, IPTV network, NGN softswitching network interface. For the end user to different business needs, the operator can flexibly select ONU terminal equipment to meet various application scenarios, FTTH/FTTB/FTTC/FTTC+EoC etc.. EPON network as shown in Figure 1 for typical.

Figure 1: typical EPON network scheme

(2) EoC

EoC is the Ethernet data transmission technology in coaxial cable. The EoC system head end, terminal, coaxial distribution network components. The head end are generally placed in optical node position, since the upperEthernet data distribution, terminal equipment; terminal on the user home access user computer or interactive set top box; coaxial distribution network from the CATV network optical node location to the user network home, in addition to the coaxial cable, also includes an active amplifier, EoC jumper, branch / distributor and other equipment.

The currently used EoC head end equipment is to access active modulation HomePlugAV technology based on theconvergence device, its main function is the data base band signal to OFDM modulation in the frequency range of 7 to 30MHz, and then mixed with the cable TV network signal transmission in the coaxial cable TV HFC network. The Eo. The EoC user end equipment used is the modulation and demodulation equipment of HomePlugAV technologybased on client, its main function is to all kinds of user terminal equipment computer, set top box, IP phone, access to the EoC system, in order to achieve the coaxial cable for two-way broadband access medium.

According to the radio and television operators EPON and EoC technology, OLT is placed in the front networksystem, ONU placed on the floor, connecting the EoC (EthernetoverCable) in office equipment, through the HFChome. The user through the coaxial cable transmission cable and receives the data signal, at the same time does not affect the transmission of CATV signal and receiving. EoC host maximum bandwidth can reach more than 80M,with up to 64 from the machine, a number from the machine sharing host bandwidth. The host in the connectionnumber from the machine, the machine can automatically adjust the bandwidth, QoS can be set from the machine'sbandwidth, the host machine can be SNMP network management. The transmission distance bridge can extend the cable TV signal, across various CATV signal amplifier, to achieve the two-way data transmission, realize the datasignal and TV signal line transmission.

The current mainstream EoC products using HomePlugAV/BPL technology, EoC head end equipment for cablebridge switch, cable bridge switch is on unidirectional cable TV amplifier span coaxial data network equipment, it will be mixed signals through frequency division method, the data signal does not pass through the amplifier, the cable TV signal is amplified by the cross connector again with the data signal mixing.

Cable bridge switch adopts a modular design, the main module, CATV module, ONU module, EoC head end module,main control module. These modules as an optional module configuration in the corresponding box. The main control switch module only in multi port cable bridge switches can be applied. The benefits of modular design is more flexible, can satisfy the flexible cable operators demand in different periods and long term, minimizing the investment cost, high return.

Different regions of the operator according to the economic development situation, the user density, cover thebandwidth demand rate, opening rate and user, cable bridge switch choose different quantity of interface, can choose indoor or outdoor installations. The user terminal equipment according to the number of the network interface is divided into single interface, interface and the four network interface. The number of EoC head end module can be configured according to need, each module provides a TV signal input and a Cable mixing, mixedsignal and transmit and receive data signals and the cable TV signal. CATV access module supports a single CATVaccess, provide a channel cable TV interface, transmission cable TV signal.

The main end can support multiple even under the coaxial channel through the coupler. Using optical devices with high performance, light splitting ratio was 1:32 to cover the distance to reach 20km, splitting ratio of 1:64 to cover the distance to reach 10km. Optical divide ratio is 1:64 the average bandwidth can reach 15Mbit/s, to meet thebandwidth requirements of the users.

Application of EPON+EoC (3)

Technical renovation on the traditional cable television networks using EPON and EoC technology, bidirectionalcable using EPON completed equipment modification, user coaxial cable access network bidirectional transformation,using active EoC network, active connection in ONU EoC head end, covering all the user node below, using the EoC user access to a bidirectional the demand of user. This one-way broadcast transmission network construction for the two-way transmission network.

Typical application of networking scheme of EPON + EoC as shown in Figure 2, cable bridge switch placed on thecorridor or outdoor, covering a building or a unit. Now the network has been laying optical cable bridge switch node,not through the configuration CATV module, RF cable access to cable bridge switches, ONU module configuration in the cable bridge switches, data or interactive television signal transmission.

Figure 2:EPONEoC application scheme

If the network due to the light receiver down, cable bridge switches require integrated optical receiving function.When the cable bridge switches need to configure the CATV module, through the fiber will be access to the cabletelevision signal switch. ONU module configuration in the cable bridge switches, data or interactive television signaltransmission. Another situation, if the network has been laying optical node, ONU placed on the outside of the building, access to several cable bridge switch single port, data signal through a cable connected to the cable bridge switches, data or interactive television signal transmission, the TV signal through the radio frequency cable accessto cable bridge switch.

4 Conclusion

Radio and television operators using EPON and EoC technology to contribute to the comprehensive utilization ofcyber source, fast to complete the construction of NGB access layer, the realization of digital bidirectional transformation, reduce the amount of redundant construction, saving construction and operation and maintenance cost. The EPONEoC scheme, the user does not need to make any changes to the indoor wiring, only need to addthe CNU terminal equipment can realize two-way, interactive, multifunctional, multi service, enjoy the rich content of three nets fusion brings. EPON + EoC scheme can improve the cable TV network technology level and service capability, play a cable television network bandwidth, low cost, easy popularization advantage, make the cable digital TV multimedia information platform into thousands of households.

Bidirectional Transformation of CATV network is carrying, provide triple play the most important business platform,will become the most important infrastructure of modern information communication in social activities. CATV NetworkBidirectional reconstruction after, with access mode of optical fiber and coaxial cable to provide broadband accesscan be extended to every family user, can meet the bandwidth requirements of the SD and HD TV, users enjoy thepicture quality will be sharper image lifelike, more clearly. Through this "high road" users can quickly and easilyhandle daily information, convenient service and enjoy the information society.

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