Brief Overview of 9 Advantages of SDH Equipment
SDH optical terminals offer large capacity, typically ranging from 16E1 to 4032E1. SDH is an integrated information transmission network that combines multiplexing, line transmission, and switching functions, operated by a unified network management system. It was proposed by Bell Communications Research Institute in the United States as Synchronous Optical Network (SONET). SDH enables effective network management, real-time service monitoring, dynamic network maintenance, and interoperability between equipment from different manufacturers. It can significantly improve network resource utilization, reduce management and maintenance costs, and achieve flexible, reliable, and efficient network operation and maintenance. Therefore, it has become a hotspot in the development and application of transmission technology in the global information field and has attracted widespread attention. The rapid development of SDH is inseparable from its own characteristics. Below, Guangzhou Yinxun provides a brief overview of the 9 advantages of SDH equipment:
(1) SDH transmission systems have a unified frame structure internationally, with standard digital transmission rates and standard optical interfaces, enabling interoperability of network management systems. This provides excellent horizontal compatibility, allowing full compatibility with existing PDH and accommodating various new service signals, forming a globally unified digital transmission system standard and improving network reliability.
(2) The code streams of different levels in the SDH access system are arranged in a highly regular pattern within the payload area of the frame structure, and the payload is synchronized with the network. Using software, high-speed signals can be directly dropped and inserted into low-speed tributary signals in a single step, achieving one-step multiplexing. This overcomes the PDH plesiochronous multiplexing process of decomposing all high-speed signals level by level and then regenerating and multiplexing them. By greatly simplifying DXC and reducing back-to-back interface multiplexing equipment, it improves the transparency of service transmission in the network.
(3) Due to the adoption of advanced Add-Drop Multiplexers (ADM) and Digital Cross-Connects (DXC), the network's self-healing and reconfiguration capabilities are very strong, resulting in high survivability. Since the SDH frame structure allocates 5% overhead bits for signals, its network management functions are particularly powerful and can be unified into a network management system, playing a positive role in network automation, intelligence, channel utilization, reducing network maintenance costs, and enhancing survivability.
(4) With multiple network topology structures, SDH networks are highly flexible. They enhance network monitoring, operation management, and automatic configuration functions, optimize network performance, and also make network operation flexible, secure, and reliable, providing comprehensive and diverse network functions.
(5) SDH possesses both transmission and switching capabilities. Its series of equipment can be freely combined through functional blocks to implement networks of different levels and various topologies, offering great flexibility.
(6) SDH is not exclusive to a specific transmission medium; it can be used over twisted pair and coaxial cable, but optical fiber is required for high data rate transmission. This characteristic indicates that SDH is suitable for both backbone channels and branch channels. For example, China's national and provincial cable television backbone networks use SDH, and it is also compatible with Hybrid Fiber-Coax (HFC) networks.
(7) From the perspective of the OSI model, SDH belongs to the physical layer at the lowest level, with no strict restrictions on higher layers, making it convenient to adopt various network technologies over SDH, supporting ATM or IP transmission.
(8) SDH is strictly synchronized, ensuring the entire network is stable and reliable, with few bit errors, and is convenient for multiplexing and adjustment.
(9) Standard open optical interfaces enable horizontal compatibility on basic optical cable sections, reducing networking costs.
Due to the numerous advantages of SDH, SDH equipment has achieved tremendous development in both WAN and private network fields. Telecom operators such as China Telecom, China Unicom, and China Broadcasting Network have all deployed large-scale SDH-based backbone optical transmission networks. With its obvious superiority, SDH has become the mainstream in the development of transmission networks. SDH technology, combined with advanced technologies such as Wavelength Division Multiplexing (WDM), ATM technology, and Internet technology (IP over SDH), has made SDH networks increasingly important. SDH has been included in the application projects of high-speed communication networks for the 21st century by many countries and is recognized by the telecommunications industry as the development direction of digital transmission networks, with broad commercial prospects.