支持用户SLA的公平EPON带宽分配算法

A Fair Dynamic Bandwidth Allocation Algorithm for EPON with Service Level Agreement Supporting

动态带宽分配算法是EPON的关键技术之一.现有的DBA算法在带宽利用率、公平性方面有待提高.借鉴现有算法的思路,结合公平性的现实意义,提出了支持多用户SLA的公平算法SOABR算法.SOABR算法消除了时隙末空闲和DBA延时,带宽利用率达到了最优化;按SLA比例为用户授权带宽,实现用户间公平.仿真实验证明,与改进的IPACT、HPFCT、Chadi Assi算法等3种典型算法相比,SOABR算法带宽利用率最高,真正支持用户等级划分,在区分服务模型下各类业务延时最佳.

Dynamic bandwidth allocation algorithm （DBA） is one of the major concerns in Ethernet passive optical networks, the emerging next generation broadband access solution. Various existing DBA schemes are not consummate with respect to uplink utilization or fairness. A new DBA named SOABR is presented, which boosts the link efficiency to maximum by completely avoiding idle stages of uplink resulting from DBA scheme and eliminating unused slot remainder. Instead of according to ONU＇s weight, SOABR hierarchically allocates bandwidth proportional to subscriber＇s service-level-agreement bandwidth, hereby improves inter-user fairness. The novel algorithm is compared with three typical algorithms： modified IPACT, HPFCT and Chadi＇s algorithm in simulation experiments. SOABR can achieve higher link utilization and lower packet delay than the others under extra heavy load. Regarding supporting subscriber＇s service level agreement and fairness, SOABR has the advantage in that variant users can obtain differential bandwidth according to their service levels under all circumstances and end-to-end delays for highest priority traffics of each user are equal and acceptable.