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Adopting 1550 GEPON technology to construct a metropolitan area network is very suitable for the development of wired broadband. GEPON is multiplexed on the 1550 cable TV optical transmission system through low-cost WDM. It does not need to be modulated to RF like CMTS/CM to bring a series of technologies and cost troubles . 1550/1490/1310 three-wave shared optical splitting platform can build a very competitive and relatively low-cost wired broadband network to meet the needs of multiple services.
1550 transmission system advantages
In the 1550nm transmission system, the laser adopts external modulation, which not only has the advantages of high output power, high reliability, low unit optical power cost, low fiber loss, , but also can perform multi-stage amplification. Optical amplifiers have little effect on CTB and CSO indicators, very suitable for the development of China's TV network. Its advantages are mainly reflected in the following aspects:
1. The combination of 1550 optical transmitter and optical amplifier can realize the distribution of high power 13dBm-24dBm. Combined with the use of optical splitters, it can achieve flexible power distribution and flexible network structure. The 1550nm optical transmitter combined with high-power EDFA dense coverage optical nodes is a popular international networking solution.
2. The transmission loss of the 1550 optical transmission system in ordinary G.652 fiber is only 0.25 dBm/km, which makes the unit cost of the 1550 optical transmission system per milliwatt better than that of the 1310 system.
3. Only a few 1550 optical transmitters are needed for the entire network, so only a small amount of RF connections are required, and there is no need to add an expensive RF wiring management system like the 1310 system. The 1550 transmission system only needs 1+1 hot backup, which is simple and highly reliable to meet the telecom level requirements.
4. High index of 1550 transmission system in network distribution. The idea of the 1550 optical transmission system solution is to use the current internationally popular GEPON technology ideas of FTTP and FTTH , which can meet the needs of large video and interactive digital transmission for users in the next ten years.
EPON system advantages
The PON network bandwidth can reach a two-way 2.5Gbps rate. The transmission distance is up to 20Km, and the tree-shaped network structure composed of passive splitters has a maximum split ratio of 1:128. This point-to-multipoint network structure is very suitable for building broadcasting and television FTTx access networks.
1. Saving. Based on the P2MP network structure, only one fiber is required between OLT and ODN, which saves a lot of fiber resources and optical transceivers.
2. Reliable. The signal does not pass through active electronic devices during PON transmission, which means that the maintenance cost will be significantly reduced, the number of PON components will be small, and the point of failure will be reduced accordingly, and the operating expenses will be reduced to the greatest extent.
3. Long distance. The PON transmission distance is 10～20km, which completely overcomes the limitations of Ethernet and xDSL technology in distance and bandwidth, making the deployment of the access scheme more flexible.
4. High bandwidth. Compared with other access methods, the bandwidth is higher, and the PON network bandwidth can reach a bidirectional 1.25Gbps rate.
5. Flexible. PON supports multi-level connection of optical splitters, reasonable match of cascade splitter, and more flexible networking. It is especially suitable for occasions where user access information points are scattered and fiber resources are relatively scarce.
The transformation of the network to an all-IP network, multi-service operations, and fiber optic networks has become a general trend. EPON (passive optical network) is such an all-optical network, and his ultimate goal is to achieve "fiber to the home". Tree-shaped network structure can effectively expand the service coverage; single fiber plus passive splitter transmission can greatly save fiber resources; full-service access, regardless of IP services or TDM services, can be achieved on a unified platform ,and ensuring its service quality; simple structure and powerful network management, which greatly saves maintenance costs.These characteristics make EPON technology get rapid development.
Prevail Optoelectronics combines own technical advantages and market needs, mainly promotes the following two solutions: single-fiber triple-wave solution and dual-fiber triple-wave solution.
1. Single-fiber triple-wave solution
In the single-fiber triple-wave solution, the downstream 1550nm optical signal and the PON 1310nm/1490nm optical signal of the broadcast and television service are combined into a fiber physical channel by the WDM wavelength division multiplexing device in the front-end machine, finally reach to users by transmission and splitting of ODN device.In the user's home, using our single-fiber triple-wave, data +CATV optical receiver 2-in-1 ONU, it can directly output broadcast TV signals and broadband data signals. An optical receiver with a WDM PON signal loop-out can also be used to connect the looped-out PIN signal to an existing ONU, thereby realizing the separation and output of broadcast TV services and broadband data services.
The advantages of the single-fiber triple-wave access solution are as follows:
* End-to-end management: Because single-fiber triple-wave network structure is end-to-end, user terminal equipment can be easily managed. Network administrators can implement operations such as remote service activation, fault maintenance, and service shutdown.
* Low ODN cost: Because broadcast TV signals and broadband data signals are transmitted on the same physical fiber, this solution greatly reduces the construction cost of the ODN network splitter and core resources from the front end to the user's home .
2 Dual-fiber triple-wave solution
Broadcast TV service downstream 1550nm optical signal and PON 1310nm/1490nm optical signal are transmitted in different cores, and each reaches the user's home through different physical transmission channels. After entering the home, the CATV optical signal input FTTH optical receiver to receive and provide RF electrical signals, and the PON optical signal input FTTH ONU to provide broadband data services.
The advantages of the dual-fiber triple-wave access solution are as follows:
* No wavelength interference: The transmission channels of broadcast optical signals and data bidirectional optical signals are physically independent fiber channels, which avoids the problem of wavelength interference.
* Low user terminal cost: Compared with the single-fiber triple-wave solution, the dual-fiber triple-wave can save a lot of user terminal DWDM equipment costs.
* High reliability:Completely eliminating outdoor active equipment , high reliability , which can save a lot of costs of operation and maintenance and outdoor equipment power supply.