Dynamic Resource Allocation Algorithms In Next Generation Passive Optical Networks

As a popular solution for access networks,Passive Optical Network(PON)has been widely deployed recently.However,it is more and more difficult for the traditional Time Division Multiplexing Passive Optical Network(TDM-PON)to meet the growing bandwidth requirements of users.As a result,Next Generation Passive Optical Network(NG-PON)has be developed,which can provide a higher quality and lower cost broadband access service for more users.With the explosive growth of users' bandwidth requirements,NG-PON will carry more and more data services.Therefore,the efficient dynamic resource allocation algorithm is one of key issues to improve the network performance of NG-PON.First,this paper introduces the background,development process and various technical solutions of NG-PON.On this basis,some classical Dynamic Bandwidth Allocation(DBA)algorithms for TDM-PON and Dynamic Wavelength and Bandwidth Allocation(DWBA)algorithms for Time and Wavelength Division Multiplexing Passive Optical Network(TWDM-PON)are investigated.Secondly,in order to solve the problem that the heterogeneous propagation delays of ONUs in Long Reach Passive Optical Networks(LR-PON)lead to more channel voids,an Online Partial Multi-thread Polling(ON-PMTP)algorithm has been proposed,which can dynamically adjust the grant number of some ONUs according to the channel void of the next polling cycle to allow them to upload data in advance.In addition,ON-PMTP can adjust the maximum guaranteed bandwidth of each polling cycle and the corresponding cycle time according to network load,so that the polling cycle time can be better adapt to the change of network load.It is beneficial to reduce average packet delay and to improve upstream channel utilization.Thirdly,an improved Dynamic Wavelength and Bandwidth Allocation(IDWBA)algorithm is proposed for Wavelength Agile Passive Optical Network(WA-PON).The algorithm takes advantage of the flexible allocation of wavelengths in WA-PON to allocate wavelengths as much as possible to the ONU with a burst bandwidth requirement,while to avoid excessive allocation of wavelengths for a ONU with low load as far as possible,which is beneficial to reduce the bandwidth waste caused by the bandwidth guard and the overhead of control frame and to decrease the average delay and packet loss ratio.Finally,the performance of ON-PMTP algorithm and 1DWBA algorithm is evaluated by using OPNET simulation software to build LR-PON and WA-PON simulation platform respectively.The simulation results show that compared with the existing algorithms,the ON-PMTP algorithm can improve the performance in terms of packet delay and upstream channel utilization,and the IDWBA algorithm can reduce the average delay and packet loss ratio.