SDH Directly Access In Broadband Switching

With the trend of broadbandization and digitization in communication market, the traditional switched network which bases on PSTN can not meet new developing requirement. Developing Next Generation durative-developing Network has been the common expectation in Telecommunication field. NGN which bases on optical network and distributed transmission technology will be a researchful integrated network with hardcore"soft switch". However, before mature NGN come into being, how to optimize the current network and make it steadily work up to NGN has been a task in telecommunication domain.This article launched on the current SDH technology and raised an engineering application design which set up a feasible engineering solution for implementing SDH directly access and finally realize the smoothly evolvement into NGN.We research this task based on NGS switching system, adding SDH access function, thereby carry out the SDH directly access on NGS. NGS is a switching system which can realize smoothly evolvement to NGN. It possesses MPSR broadband switch network with Multi-slot Cell and ability of Multi-path self-routing. The internal switch function of NGS is independent of external service. NGS adopt the full-separate-control mode which can conveniently integrate kinds of function into varied modules, so new service can be easily introduced by adding new function modules. For the NGS characteristic of"the full-separate-control mode"and"the internal switch function of NGS is independent of external service", we add a broadband module in NGS system in design phase. This module makes NGS realize SDH directly access by translating STM-1 format from SDH network node to MPSR internal format.This design focus on the design of SDH line termination and TDM-MSC interworking module and final hardware test solution.SDH line termination module implements SDH termination function for SDH access, including following parts: SDH termination, automatic protection switch, clock recovery, transmit clock and data recovery, ect. Besides adopting PMC-Sierra commercial chipset 2*PM5316 and 4*PM8316 for SDH access, we also introduce 1+1 APS to this module for enhancing system ability of security and error toleration. TDM-MSC interworking module can implement the format conversion between TDM and MSC to realize the data switching in MPSR switch network. This module carries out interactive logical by two FPGA chips. According to the requirement from manufactory of expeditiousness and convenience, the hardware test has been given the completive solution and the experiment data show that is a successful design.