Design And Implementation Of VDSL2System On-line Reconfiguration

With the development of the access network technology, the amount of thewideband users increases day by day. Users put forward higher request for quality andtypes of online busuness. VDSL2technology, which has been introduced by ITU in2006, makes full use of copper resources to realize high speed access through theexisting copper twisted pairs. It has become the preferred technology for current accessnetwork.This subject is a part of school-enterprise cooperation projects of VDSL2systemsdevelopment. Theoretically, VDSL2technology can provide a data transmission rate upto100Mbit/s. Due to the influence of line crosstalk and impulse noise, the actual ratewould often not achieve the anticipated performance. In addition, there is a certaindistance between the line stability and the commercial standards. The onlinereconfiguration technology, which is one of the main technical features of VDSL2systems, primarily used to enhance the ability of the system to adapt to the line changes,so as to improve the stability of the system.Generally speaking, the system initialization time is relatively short (VDSL2system needs about3s), and the system estimates the channel roughly, OLR (on-linereconfiguration) can be used for optimizing the system parameters. Moreover, when thesystem enters the showtime stage, the line may encounter some interference when thesystem enters the showtime stage. OLR can adjust the line parameters adaptively basedon the current characteristics of the channel while the link connection won’t beinterrupted during the entire process.This paper analyzes and designs the three major methords of OLR technology: bitswapping, seamless rate adaptation, and seamless of rate switching.This paper introduces the three OLR methods on the following aspects. Firstly,make a detailed theoretical analysis. Secondly, carry out algorithm and do optimizationand matlab simulation for each method. Finally, realize the three algorithms by coding.Design the scheduling mechanism for the whole system reasonably, test and validate thethree methods used in the system. The results show that the design meets the therequirement of G.993.2standard.