Research And Design Of IP-DSLAM/ADSL Downlink Transmission Line

With the trend of core network over IP and DSLAM, the ADSL-Transmission Unit-Central equipment of xDSL has been evolving towards the direction of IP-based, intelligent and scalable. Due to its high speed of downlink, ADSL is outstanding of all xDSL technologies and becomes the mainstream technology. In order to adapting the cohesion to core network and enhancing the access density, there is a high demand for IP-DSLAM with the the characteristics in the market. In this paper, it investigates ATCA based ADSL IP-DSLAM technology, which can provide multi-access and scalable faction.This paper is one of the important parts of the Intel university project--Research and Design of IP-DSLAM based on NP. First of all, this paper analyses the IP-DSLAM principle, NP technology, ADSL modem technology and the downstream transmitting technology. Then, it designs the whole DSLAM transmission line. On the basis of previous work we complete the design of the downlink transmission line of the ADSL system, and describe the data processing flow. Moreover, it deeply describes the sub-modules: RS, Grid Code, IFFT, and CP, and give the particular scheme of each module. According to these implementation schemes we realize these designs on QuartusII 6.0 software platform.by coding with VHDL. Furthermore, we simulate the system based on FPGA with QuartusII 6.0 time analysis tool and ModelSim SE 6.0 post simulation tool. Following that, by analyzing simulation result from the aspects of resource, frequency and time, this paper provides theoretical foundation for increasing the number of accessing subscribers on single board of DSLAM based on ATCA structure. Finally, the paper gives a design scheme of a 64 ADSL ubscribers.