# A Dynamic Restructuring Algorithm Based on Flexible PON Slices
## 1 Introduction
The scheme integrates the characteristics of 5G fronthaul and IoT, and can provide guaranteed bandwidth for each slice on the premise of meeting the delay requirements of fronthaul [17]. In addition, some studies have considered the fusion scenario of fiber access and wireless access, such as the Fi-Wi access. [PERSON] et al. proposed a slicing scheme based on LSTM neural network prediction in elastic optical access networks, which not only has higher prediction accuracy than traditional algorithms, but also can adjust the slicing boundaries in advance to offset the delay of moving resource boundaries when resources are scarce [18]. Slicing technology is favored by researchers of various components of the network. In recent years, the hybrid communication scenario with multiple slicing technologies has also become one of the key research directions [19]. Although the slicing technique is widely used at present, there are few studies in the access network scenario with multiple OLTs. This study mainly focuses on network slicing technology on large campuses with multi-OLT centralized deployment. In order to make full use of the exchange capability of OLTs and relieve the traffic pressure of the access network, there have been some excellent studies [20; 21]. [PERSON] et al. proposed a dynamic optical network units (ONUs) grouping algorithm (DGA) based on centralized flexible PON to reduce the outbound traffic of optical line terminals (OLTs) and relieve the traffic pressure of the core network. DGA divides all nodes into two parts in each iteration to calculate the optimal allocation scheme, and deletes nodes in one part after that. The remaining nodes are then divided into two parts to calculate the optimal allocation scheme, and so on until all nodes are deleted [20]. However, DGA does not make further selection when the node switch gain is equal to 0 in each graph cutting, which will affect the subsequent graph cutting and may miss some better results. Therefore, another dynamic ONU slicing algorithm (DONUSA) was proposed in [21], which not only achieves a better traffic gain in the case of a large number of OLTs and ONUs under each OLT, but also has lower complexity. However, the performance of DONUSA is affected by the number of devices. Considering that the problems of DGA are caused by multi-step iteration, a new dynamic restructuring algorithm (DRA) is proposed in this paper, which directly divides the graph into subgraphs of the target number and puts all the cyclic calculations and operations in a one-step iteration. In this way, the influence of the previous node selection and exchange process on all the subgraphs will be considered in the next calculation. Simulation results show that DRA can obtain a better traffic gain than DGA and DONUSA, which indicates that the proposed DRA has more positive significance to relieve the traffic pressure. The rest of the paper is organized as follows: Section 2 introduces the access network architecture used in this paper and models the dynamic slicing problem based on the system architecture. Section 3 displays the proposed algorithm and the parameters used in the algorithm. Then in Section 4, the simulation conditions and the performance index of the algorithm are given, and the simulation results are preliminarily summarized. In Section 5, the reasons for the simulation results are explained and our future research direction is summarized. Finally, Section 6 is the summary of the full text.