Design And Simulation Of ADSL System Upstream Transmission Line

At present, the per-card access density of common DSLAM device is 48 or 32 lines, which can not meet the market's high density requirement. By researching ADSL system design and analyzing its performance, this paper proposed an implementation scheme supporting 64 ADSL transmission lines based on ATCA architecture, which has the advantage of high throughput reliability and high expansibility.This paper is an important part of Intel University Plan project "Research and Implementation of IP-DSLAM Based on IXP2350" and it focuses on the implementation of 64 lines ADSL access on single board based on ATCA platform. Upstream data line of the ADSL system is designed and implemented in this paper; and we verified the system by simulation. The first part of this paper summarizes the background and status in quo of ADSL technology, on the basis of which we conclude that it is meaningful to study ADSL and increase accessing port density of single board. After researching G.992.1, we divide ADSL system into three parts: front-end analogic processing unit, digital signal processing unit and user dataflow processing unit. Then, we analyzed the process of the system and deeply described the sub-modules: FFT demodulation module, grid code (Viterbi Decoding) decoding module, Forward Error Correction decoding (RS) module and CRC decoding module. Moreover, we give the particular scheme of each module.In this paper we also made system simulation and analyzed the result from aspects of function and performance, which provided theoretical foundation for increasing the number of accessing subscribers on single board based on ATCA platform. The last part of this paper presents the future work of the design of ADSL upstream data link.