With the development of social informatization, people are no longer satisfied with a single voice, TV or Internet service, and diversified business needs put forward higher requirements for network operators. Especially for the traditional cable TV network operators, the original network is mainly a one-way video broadcasting service, and in the Internet era, it is facing the transition to a multi-service integrated operator. The network must be able to carry video, data and voice services, and have two-way. , interactive, multi-service, multi-functional capabilities.
Operator triple play solution
    The three-network convergence mainly refers to the convergence of services, and adopts a new network structure to meet the needs of three types of services including video, data and voice. The triple play of the broadcasting and TV operators can be realized based on the PON system. The principle is to integrate the PON system and the CATV system through WDM (Wavelength Division Multiplexing) technology to transmit 1550 nm, 1490 nm and 1310 nm signals through one optical fiber. The network structure topology is shown in Figure 1.
Figure 1 Schematic diagram of three-network convergence network structure

    PON (Passive Optical Network) is a P2MP (point to multiple point) network system. It consists of three parts: OLT (Optical Link Terminal), ODN (Optical Distribution Network), and ONU (Optical Network Unit). At present, there are mainly EPON and GPON technical solutions.

    The three-network convergence network adopts WDM technology to realize the same optical fiber transmission with the uplink and downlink optical signals of the PON system. Among them, the downlink signal is divided into two ways, one is the PON data signal, the optical wavelength is 1490nm; the other is the CATV broadcast signal, and the optical wavelength is 1550nm. The uplink signal is a PON data uplink signal with a wavelength of 1310 nm.
Triple play solution
The three-network convergence solution based on PON system provided by Wolck is shown in Figure 2:

                                                           Figure 2 Three-network convergence solution based on PON system

    Description of the three-network convergence solution based on PON system:

The central office (computer room) OLT is the core of the entire PON system, providing a high-speed interface for accessing information such as voice and data, and providing a PON interface for the passive optical distribution network downward. The OLT is the control center of the PON system, through which the network management system completes the operation, management, and maintenance of the PON system.

    The central office (computer room) EDFA amplifies and transmits the received CATV front-end signal. The upper interface is connected to the CATV front-end optical transmitter, and the lower-link interface is connected to the WDM equipment input port.

    The central office (computer room) WDM equipment is a passive device that multiplexes the PON uplink and downlink signals and the CATV downlink signals, and is installed between the OLT/EDFA and the ODN.

    The client ONU provides users with service interfaces such as data, CATV video and telephone. The protocols such as Ethernet and GEM are used to realize the transparent transmission of user data by the PON system. The CATV service data output tastes the RF interface, and the STB (Set Top Box) is connected, and then the TV is connected to the program for viewing.

    The ODN network between the OLT and the ONU is a passive optical distribution network composed of an optical splitter and an optical fiber. Its function is to complete the distribution and convergence of optical signals, so that downlink data is distributed to each ONU terminal, and uplink data is aggregated. Go to the OLT device. The ODN network can realize multi-level splitting according to the actual use environment, and it is recommended to split the first level.

    In addition to EDFA and various types of ONUs with CATV interface, WOLCK triple-play products can also match PON series products of FTTH network. The three-network convergence products are mainly for the construction of broadcasting and television networks, providing them with the last mile of fiber access. .