CWDM Deficiencies

The biggest problem with CWDM technology is that its cost advantage over DWDM equipment is still not obvious enough. Optical transceiver modules and optical components are key to reducing costs. However, due to the small size of the market, the supplier’s shipment volume is not large, so the cost advantage of the device is not obvious. Another way to reduce costs is to simplify device functionality, which results in reduced system reliability and manageability. DWDM products with decreasing prices also put a lot of pressure on CWDM technology, and DWDM technology can form a complete metropolitan DWDM network, so the scalability is good, and the pressure on CWDM is relatively large. The number of optical channels (wavelengths) supported by current CWDM devices does not exceed eight, mainly because the manufacturing process of E-band optical transceiver modules is not mature. In addition, G.652C optical cables that eliminate water absorption peaks are less used in the existing network. Therefore, the market demand for E-band optical transceiver modules is not large. There are still many technical problems with CWDM systems with higher speeds and longer transmission distances. Such as 10G system dispersion problem, ultra-wideband optical amplification technology. In addition, the standardization process needs to be accelerated, especially for the service interface functions that require operator guidance.

Direction of development

One of the key factors that restrict the development of CWDM products is the price of optical transceiver modules and multiplex demultiplexing devices. With the development of the market and the advancement of manufacturing processes, further reduction of equipment costs is an important development direction. Develop E-band optical device technology to make it mature as soon as possible. Develop 10G rate optical channel technology to improve the capacity and scalability of CWDM systems. Supporting various business interfaces is the direction of CWDM development. The demand for the multi-service interface of the metropolitan area network access layer is the driving force for further development of multi-service interfaces by various vendors. The CWDM equipment will provide various service interfaces such as FE, GE, SDH, ESCON, and FC. Another development direction is the ability to combine MSTP or high-performance routing switching equipment as a means of extending line-side capacity for MSTP devices or high-speed routers. Providing multiple levels of optical layer and business layer protection is also a development direction to meet the needs of different customers. The network management technology and equipment security and reliability are further improved to improve the competitiveness in the market. For the newly launched G.652C fiber, since the price of G.652C fiber optic cable is twice that of G.652B, and the E-band CWDM optical transceiver module technology is not mature, the full-band CWDM is applied in the short term (1-2 years). The possibility of equipment is not great. The use of G.652C fiber optic cable has the problem of large investment and no benefit in the short term. Therefore, the application of G.652C fiber in the metropolitan area user optical cable network is limited.

Currently, several companies are launching products related to CWDM. Beijing Senrunda Company launched SRD series CWDM products, which can support 2-16 channels and active passive products. The widewav series of CWDM modules from LuxN support 8 CWDM channels or support 4 CWDM channels plus 16 DWDM channels. Time Warner has signed a long-term purchase agreement with LuxN to deploy Gigabit Ethernet in New York, Ohio and other locations using wavsystem DWDM equipment with widewave modules. Ocular’s products using CWDM technology include the OSX-6000 and OSX-1000 switches, and the biggest feature is the SAN service that provides dedicated wavelength channel services for high-end users.

Post time: Jul-02-2018
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