The Optimization And Research On DBA Algorithm Of GPON System

As the development of backbone network Enterprise network and home network presently, the huge increase in Internet traffic, which makes the shortage of access network become more prominent."Last kilometer" is still the bottleneck of high-capacity backbone network and the LAN (Local Area Network). Gigabit-capable Passive Optical Network is the latest generation of Broadband passive optical access technology, based on ITU-T recommendation G.984.X, and support multi-rate.GPON has the advantages of high efficiency, full-service, QoS guarantee and strong survivability, also can fully take the views of the operators into account.Now,GPON has been have a good technical base and able to meet the demand of quantities of commercial, GPON has been achieved smooth evolution from the current GPON technology to the futurelOGEPON and10GGPON technically,the time is ripe to choose GPON technology as the mainstream technology of the optical access construction.s, we generally consider that GPON is the best solution for "Last kilometer ". It can be seen that, researching the key technologies of GPON has very important significance in the longer term.The paper begins from the development history and current situation of GPON, explains its structure, protocols, and key technologies in detail, deep investigate the dynamic bandwidth allocation algorithm of the key technologies which includes transport containers, DBA (Dynamic Bandwidth Allocation) protocols and operating modes, as well as the working principle of dynamic bandwidth allocation.The core of this paper is research and optimization of dynamic bandwidth allocation algorithm, by doing a comparative study of several existing typical DBA algorithm, the paper puts forward an improved graded poll algorithm which based on T-CONT.The improved algorithm divides business level into four levels from high to low corresponding to the four types of T-CONT,, from T-CONTI T-CONT4business, their grades are getting lower and lower, Then follow from high to low level, execute dynamic allocation of bandwidth in proper oder according to the bandwidth needs of business and the right weight.The article also describes the idea of the algorithm and the dynamic bandwidth allocation for each step, and drew the logic block diagram in accordance with the bandwidth allocation procedure.Lastly,buid a GPON system model,node models of OLT and ONU,process models of the main processing module with OPNET, this model abolished the node of the ODN, and add a delay compensation state to the process model of the ONU, so the delay performance of such experiment is closer to reality.Then conduct simulation experiments in this simulation platform,the simulation results show that the improved algorithm in this paper is in line with the ITU-T recommendation,also superior to the original algorithm and meet the full-service QoS guarantee of GPON system well.