VDSL2Loop Diagnostic Function Designd&Implementation

VDSL2is the latest and fast xdsl network access technology, it slove solve thebusiness needs of the growing problem of high-speed multimedia, and rapid growthof data and network users. VDSL2provides the perfect solution for the fiber to thehome. To the VDSL2service, how to locate the fault quickly is very important.Design and implementation of VDSL2loop diagnostic function is studied in thispaper, to locate the position of access failure of the the VDSL2network quickly.Loop diagnostic function can obtain loop parameters of the channelcharacteristics quickly and easily. When the loop failure happened or other casecause the loop cannot be activated, need to test the loop conditions. The traditionalsolution is to dispatch maintenance technicians to attach test equipment to theG992.3protocol loop to get the loop channel conditions, but this method isinconvenient and costly. Another solution is to set VTU-O make VTU-O and VTU-Renter loop diagnostic mode, the loop diagnostic mode enables the immediatemeasurement of channel conditions at both ends of the loop without dispatchingmaintenance to attach test equipment to the loop. After loop diagnostic mode, theresulting information helps to isolate the location (inside the premises, near thecustomer end of the loop, or near the network end of the loop) and the sources(crosstalk, radio frequency interference, and bridged taps) of impairments.VDSL2G993.2protocol and software module functions and various parts ofthe existing network central office software architecture is analysised by this paper.loop diagnostic function can be implemented by increasing loop diagnostic functionmodule in the existing software architecture.In the process of realization of VDSL2loop diagnostic mode; firstly, the state machine is implemented, in order to controlthe process of transmission of the loop diagnostic. The function makes the loop themessaging processes comply with protocol standards.Secondly, The functions ofVDSL2message sending, receiving process and SOC message transfer mechanism.Message experience, timeout retransmission and exception handing are included inthis function, in order to guarantee the correctness of mutual message.Finally, thefunction of data transceiver in the loop diagnostic functions is implemented. In orderto ensure achieve reliable data transmission even in the case of poor channelcharacteristics.Through the process of program development, first developed in the PV virtualplatform; after code completion, then the code is compiled and loaded into theFPGA board, connecting the FPGA board with modem to do debug and functionalverification. Finally, complete loop diagnostic functional development.