Possessing WDM-TDM PON system compatible with multiple access technologies

The WDM-TDM PON system is a PON structure that is a mixture of WDM PON and TDM PON. It is this hybrid structure that enables it to have effective compatibility with multiple access technologies. Recently, the "Low-cost Multi-wavelength Ethernet Integrated Access System (λ-EMD)", a major project of the National "Eleventh Five-Year Plan", successfully completed laboratory testing. The WDM-TDM PON system has a good application status and has been recognized by experts. Next, it will be tested in the operator's fixed network to further promote it to the market.

　　With the further advancement of full-service operations, the metropolitan area network is undergoing rapid reform. The access network is closest to the user end and is subject to the strongest impact. Operators are also encountering more and more problems when deploying access networks, such as how to use limited optical fiber resources to carry the growing number of users, how to effectively manage a large number of OLT devices, and how to deal with various optical fiber access technologies. A series of bottlenecks in the access network urgently need to be broken.

　　Expand the number of users

　　As users are increasingly densely distributed, more and more users need to be included in the fiber access network, and the demand for urban fiber lines is increasing, especially in some developed cities. For operators, when deploying access networks, they have to continuously sink the OLT closer to the user end. The direct consequence of this is that the ODN network is distributed more and more complex at the user end, especially in Shanghai where FTTH is developing rapidly, Wang Xiaomu, director of the network research department of China Telecom, pointed out. This is a big worry for both users and operators. Users need to add more outlets at home, and operators need to deploy more lines to meet user needs.

　　For a TDM PON, the number of users it can carry is limited. The introduction of the WDM system also introduces 32 channels. At this time, each wavelength is split twice to expand the number of users it can carry. Hao Jun, the marketing manager of FiberHome Communications, gave an example, saying that in a general TDM PON access system, one optical fiber can carry a maximum of 64 to 128 users, but after accessing the WDM-TDM system, the number of users carried by one optical fiber can be increased to 32 times, which can effectively save optical fiber resources. It is especially suitable for areas with concentrated users and large user demand, and can effectively promote FTTH construction.

　　It is worth mentioning that the pipe hole resources in urban areas are very limited. There are no new resources to lay more optical fiber cables, and most optical fiber cables are pre-buried in advance, resulting in a shortage of optical fiber cable resources. In this case, the WDM-TDM PON system, which greatly increases the number of users carried by a single optical fiber, can play a greater role.

　　Promote centralized management of operators

　　The WDM-TDM PON system can be positioned closer to the core network in the access network. The 32 channels separated from the system can carry 32 TDM PON systems. Compared with the traditional TDM PON OLT equipment that is constantly sinking, the system can provide operators with more convenient OLT centralized management.

　　In general access networks, the distance from the central office to the user end is within 20 kilometers, and some are only about 10 kilometers. The WDM-TDM PON system breaks this convention, breaking through the bottleneck of 20 kilometers and reaching 50~60 kilometers. This directly leads to the operator's OLT covering more areas, saving a series of equipment room construction costs, enhancing the ability to centrally control the OLT, and reducing the pressure on the OLT data uplink. In addition, due to the characteristics of WDM, each wavelength can carry different services, effectively supporting operators to provide more personalized services for different customers.

　　Compatible with multiple access technologies

　　"The WDM part determines how many TDM services can be supported, while the TDM part determines the equipment capacity in each channel, and different access forms can be provided for different users." Hao Jun said the fundamental reason why the WDM-TDM PON system can carry multiple access technologies. The various wavelength division systems separated by WDM are compatible with each other and can support a variety of fiber access technologies such as 1G/2.5G/10G EPON, GPON and P2P.

　　The capacity of a single channel is determined by TDM. For the same community, different access forms can be provided according to the diverse needs of users. For the integration of different fiber access technologies such as GPON, EPON, 10G EPON, and 10G GPON that operators are currently studying, the WDM method is the most effective and realistic integration method recognized by the industry. From a broad perspective, WDM-TDM PON is a mature integration model.

　　As a key national 863 project, the WDM-TDM PON system has completed the laboratory test phase of national acceptance and has been recognized by the national "863" project team. From a technical perspective, laboratory testing is more demanding than live network testing. FiberHome is now preparing for the next step of live network testing. After the system is launched on the market, it will bring a convergence revolution to the access network.