Planning And Optimization For Passive Optical Networks

With the emergency of various new businesses, the user docking the access network bandwidthrequirements have become more sophisticated in recent years. PONs (Passive Optical Network)have the following advantages：1) easy to upgrade and cost-effective;2) providing the largebandwidth and supporting any rate and signal format;3) the high reliability;4) providing QoSassurance of different business priorities. These advantages of PONs make it to stand out in avariety of access technologies and become the main development direction of the access networktechnology. Now PONs have been accepted widely to solve the problem of the growing highbandwidth and the access of various businesses and it becomes one of the excellent solutions. SoPONs have got the extensive attention of many researchers.The planning and optimization of PONs have important significance. The planning andoptimization for PON is studied in terns of three aspects:1) the grouping and planning of the nodeof PON;2) the planning for Splitter and the upgrading PON’s capacity by the selection of optimalallocation of the wavelength and line rate with the minimum cost; the optimization of the location;4) type of switching equipment and the numbers of wavelengths for PON. In this paper, the maininnovation points and the research work are indicated as follows:1) A new method of grouping and planning the nodes for multistage PONs is proposed. Firstly,the ONU are Grouped by equal era method. Secondly, with the minimum cost of PONs, the locationand type of Splitter are planned. Trough the numerical simulation, the planning of a PON with100ONUs by equal area method is finished and the locations and types of Splitter are also planned. Thisapproach has wide applicability and high flexibility. Besides it considers the planning of PONscomprehensively. Both the grouping of ONUs and the planning of the location and the types ofmulti-stage Splitters are considered.2) A novel MILP model to minimize the cost and energy is developed to upgrade the capacityof TDM/WDM PON by a multi-step method. Multi-step method calculates the allocation ofwavelengths and the line rates in each period. Furthermore, MILP model can find the optimallocation of splitter based on the minimum cost when TDM/WDM PON is building. The optimumposition of Splitter can reduce the length of the total fiber, which is the sum of the feeder fiberlengths from each ONU and the OLT to the Splitter. In another words, it can save the energyconsumption of green PON networks and significantly reduce the fiber cost and the labor cost oftrenching and laying the fiber which is expensive in general. The optimal placement of splitter is obtained by the simulation and the results show that multi-step method has higher economicefficiency than the one-step method and WDM technology.3) We put forward an approach to plan Switching equipments and optimize the number ofwavelengths. We develop a MILP model with the minimum cost as the goal. The bandwidth ofONUs and the loss constraint in PONs includingthe loss on fiber and the loss of transceiver aretaken into account. The MILP model plans the splitting ratio and the locations of the Switchingequipments and the connections between Switching equipments and ONUs. Furthermore, thedeveloped MILP model can optimize the number of the used wavelengths. The Switchingequipments can be splitter or Array Waveguide Grating (AWG) according to the bandwidthrequirements of the ONU and the loss constraint in PON. In addition, the splitting ratio of theSwitching equipment and the number of the used are our optimization objects. Numericalsimulations show that the selection of the Switching equipment type and splitting ratio can bedecided by the bandwidth requirements and the locations of the ONUs. Three different cases havebeen achieved by changing the bandwidths and locations of ONUs: splitters as the Switchingequipments, splitters and AWGs as the Switching equipments, AWGs as the Switching equipments.In summary, the planning and optimization of PONs has been studied in terms of three aspects.The research results show that the proposed methods can provide feasible solutions for the planningand optimization of PONs. The study will help to design, realize and optimize green PONs.