The Evolution of TDM Switching: Applications and Design Considerations for High-Density Switching Matrices

摘要

TDM (time division multiplexing) switches are widely used in telephony applications, mostly due to their low cost, minimal latency and their simplicity. However, the capacity requirements are getting higher, and most single-device TDM switches can only provide up to 32K capacity. In densely populated areas such as China and India, the need has arisen for 64K, 128K and even 256K TDM switches. To meet these capacity requirements, multiple devices are necessary to construct large TDM switching networks. The methodology used to build large TDM switching networks depends on the switching system architecture in use. For TDM systems, distributed (shared-bus), mesh and centralized (star) architectures are most common. In systems that require very high switching capacity such as large media gateways and central office equipment, the centralized architecture is typically used because of its more robust, lower control and complexity, and better switching performance nature.