Epon Upstream Bandwidth Allocation Method And System Hardware

Ethernet-based Passive Optical Network (EPON), an emerging local subscriber access architecture that combines low-lost and broadband PON with Ethernet technology, is expected to be an attractive solution to the last mile problem.Firstly, we introduce the evolution of EPON multiple access technology, and study the theory and architecture of EPON in details. EPON is a point-to-multipoint optical access network, in downstream transmission, data are broadcast from optical line terminal (OLT) to each optical network unit (ONU), while it uses time-division multiple access (TDMA) and all ONUs share the same optical channel for upstream transmission. Multipoint control protocol (MPCP) can help deal with registration, ranging and synchronization issues etc. Since IEEE 802.3ah only specifies a small portion of a communication system(only physical and data link layers), the rest is considered out-of-scope, a number of interesting challenges are left for active academic and industrial research, one of them is the upstream bandwidth allocation issue.Then, we introduce the protocols such as class of service (CoS) and service level agreement (SLA), associating with multiservice for upstream bandwidth allocation. We divide the upstream bandwidth allocation issue to several separated issues, and further study their mainly resolutions, a perfect dynamic bandwidth allocation (DBA) algorithm should include these issues as more as possible. In this paper, we represent two new DBA algorithms on the base of previous work: two-level DBA with limited cycle time (TDBA) and DBA with multiple thresholds reporting according different criterions (MRDC).TDBA, combined with SLA and characteristic of DiffServ, adopts interleaved polling of limited cycle time. OLT employs class-based traffic prediction according to the queue status of ONUi and assigns a bandwidth grant to it, and then ONUi reallocates the bandwidth to each class based on actual traffic. We simulate and testify the effect of traffic bursts on the TDBA algorithm, analyze some network index such as end-to-end delay. The simulation results show that the algorithm realizes high bandwidth utilization, low end-to-edn delay, and effectively improves the QoS of EPON compared to DBAM.On the base of the simulation of the TDBA, We represent a more comprehensivethe DBA algorithm—MRDC. In MRDC, ONU collects all the information of its queues, and reports several requests according to different criterions, after OLT obtains the information of all ONUs, it polls and fairly chooses a certain threshold from the ONU's requests, and allocates to it. On the base of fairness, MRDC improve the bandwidth utilization effecitively.Finally, we also try to realize the hardware of the EPON system without any complex protocols, and design our own OLT/ONU circuits.The OLT/ONU models have five separated parts, we introduce the core CMOS chips of every part we have used, the principle of the corresponding circuits, and the details of debugging o At last, we analyse the cause of our failure, and prospect for following work.