Research On Dynamic Bandwidth Allocation Algorithm In EPON

In recent years, along with the rapid development of communication technology, thereare great changes in backbone of communication networks, but fewer in the access networkcan not meet the demand for high bandwidth users. The Ethernet Passive Optical Network(Ethernet PON) based on mature Ethernet technology. It has characteristics as follows: broadbandwidth, low-cost, compatibility, maturity, easy to maintain, operational flexibility and soon. It becomes one of the best schemes of the next generation broadband access network.AsEPON special point-to-multipoint network topology, all Optical Network Units should sharechannel bandwidth at upstream direction and use TDMA to send data. It needs bandwidthallocation technology to harmonize the various Optical Network Units sending upstream dataand to avoid conflicts. It is of great significance for bandwidth allocation technology toimprove service quality of system, delay of system and network throughput. It is one of thecore key technologies of EPON system.In this thesis, it presents working principle and the key technologies, and mainly researchon the EPON system upstream access bandwidth allocation algorithm. We analysis of thequestion of bandwidth utilization and low-load penalty of IPACT algorithm and CBRalgorithm. This thesis has proposed a modified version of a ensure QoS and dynamic pollingcycle of dynamic bandwidth allocation algorithm according to their problems. By making useof the remnant window and setting a minimum transfer window, we do better in bandwidthefficiency in low-load penalty and he bandwidth utilization of uplink channel.On the platform of OPNET, referring to the basic framework of EPON system, the thesishas established the upstream channel simulation model of EPON system.And usingconstructed EPON system simulation model simulates the algorithm. The simulation resultsshow that the improved algorithm has effectively enhanced the bandwidth utilization of uplink channel. It effectively guarantees the QoS and the fairness of bandwidth allocation forall of EPON network. It is better to meet the current network requirements of multi-servicesand multi-priorities.It is provided the reference for EPON upstream access bandwidthallocation standards of the multi-service QoS.