Method and apparatus for converting synchronous narrowband signals into broadband asynchronous transfer mode signals in an integrated telecommunications network

摘要

The network of the invention uses asynchronous transfer mode (ATM) as the exclusive transport between the central office and the outside distribution plant of either a SONET or analog facility. Telephony and other narrowband signals are transported from a local switching system over synchronous facilities to a host terminal. Digital video and digital data ATM signals are transmitted to the host terminal from a video provider and data service provider, respectively. The host terminal converts the synchronous narrowband signals to composite cell ATM format and combines these signals with the ATM video and data signals and delivers the ensemble of ATM cells over either a standard SONET transport format to a plurality of distribution managers or other network elements or analog network. To convert the synchronous signals, the host terminal of the invention includes a synchronous to asynchronous converter (SAC) that provides the format conversion needed to provide voice and other narrowband signals over ATM. The SAC also functions to agilely move between cell sizes such that the 48 bytes of the cell payload can be mapped to carry anywhere between the single and 48 connections. Thus, the SAC adjusts the cell configuration to balance performance and bandwidth use in a real-time manner. Each distribution manager consists of several functional elements including an ATM routing function that directs the ATM cells to the correct line drop or processing logic. Specifically, composite cells from the host terminal are received by the distribution manager ATM switch fabric. Based on the contents of their headers, the cells are routed by the fabric to one of several ports. If the address indicates the cells are telephony cells, they are routed to a SAC input where the telephony ATM cells are converted back to synchronous traffic and transmitted to the customer premise over a line card and narrowband drop. If the cells are data or video cells, they are routed to the appropriate interface, and out the broadband line card and drop.