Abstract: In order to solve the problems of long propagation delay and low channel utilization in passive optical networks due to long propagation distance， a dynamic bandwidth allocation algorithm for passive optical networks based on utility function is proposed. In the uplink data transmission direction of passive optical network， the optical line terminal regularly polls each optical distribution network to obtain the request information of uplink bandwidth. In the downlink data transmission direction of passive optical network， the optical line terminal loads the downlink service packets of optical network into frames and transmits data in the form of broadcasting. Combined with this feature， the similarity between bandwidth allocation and microeconomics is used. Based on the transmission power and transmission signal gain， an optimization model of allocation problem based on utility function is established， and the problem model is solved by router matrix and its inverse matrix to obtain the optimal transmission rate of each link and realize the dynamic bandwidth allocation of passive optical network. Experimental results show that the proposed algorithm has high channel utilization and low delay jitter， and can effectively improve the dynamic real-time performance of the network.

Key words: passive optical network, transmission signal gain, utility function, dynamic bandwidth allocation, router layer