本文从提高系统的带宽利用率的角度出发，充分利用网络流量的自相似

特性，提出了一种能有效提高上行带宽利用率的动态分配算法-In this thesis， dynamic bandwidth allocation algorithm TGOGT where the

two groups of ONU are granted in turn and allocation bandwidth according to the

characteristic of network traffic and their delay request for different service is brought

forward In TGOGT,all ONUs in the system are departed into two groups，and the

queue-threshold was set for every group．Two groups of ONUs report and grant in turn，

as the network load changes，OLT converts the way of granting every ONU．