# A Dynamic Restructuring Algorithm Based on Flexible PON Slices
## 1 Introduction  
The increasing demand for networks has caused great pressure on the networks since the 21 st century [1]. The PON has shown great superiority in improving network speed and became one of the main technologies of access networks [2]. Subsequently, at the full-service access network (FSAN) meeting in April 2012, TWDOM-PON was selected as the primary technology for next generation passive optical network stage 2 (NG-PON2) due to its strong scalability [3]. Furthermore, the implementation details and key technologies of TWDM-PONs were verified in the following year. However, in recent years, with the rise of the Internet of Things (IoT)/Internet of Underwater Things (IoUT), and the proposal of the \"Internet of Everything\" concept, a large number of terminals are connected to the network, and different types of terminals (e.g., underwater terminals, smart farming terminals, etc. ), which have different requirements for network reliability, delay, and other indicators [4; 5; 6; 7; 8]. The 3 GPP classifies the scenarios for next-generation access technologiesas follows: Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra-Reliable Low-latency Communication (uRLLC) [8]. In order to meet the diversified business needs of users and vertical industries, relieve the network pressure, and improve the intelligence and flexibility of the network, the concept of network slicing was put forward [9; 10]. Network slicing divides the underlying physical network into multiple logical slices that adapt to different scenarios to achieve network as a service. In recent years, studies on slicing technology have emerged in an endless stream. Network slicing technology was first proposed for resource classification management in end-to-end transmission networks [11; 12; 13]. In the process of constructing virtual network slices and providing dedicated protection in Fifth generation (5G) transmission networks, [PERSON] et al. introduced bandwidth compression and multipath supply to reduce the backup resources required for dedicated protection, which not only divided the virtual links' demand on the multipath, but also divided the virtual links' demand on multiple spectrum segments on one path, greatly saving spectrum resources [11]. [PERSON] et al. proposed a dynamic slicing method for an optical transmission network by applying mixed integer linear programming and the heuristic algorithm, which reduced the rejection probability of virtual network slicing by more than one order of magnitude at the cost of a little service degradation [12]. [PERSON] et al. proposed an end-to-end dynamic slicing scheme based on prediction in Fi-Wi networks, which uses a double exponential smoothing algorithm to predict traffic in advance, and allocates resources for multiple slices according to the predicted results [13]. Later, with the deepening and expansion of research, the outstanding characteristics of network slicing technology in flexible resource management have also been considered in access networks, including wireless access networks [14; 15] and fiber access networks [16; 17]. [PERSON] et al. proposed a scheme to deploy virtual network function (VNF) chains with heterogeneous requirements in mixed cloud infrastructure, which greatly improved the efficiency of resource utilization and the success rate of VNF chain deployment [14]. [PERSON] et al. proposed four possible slicing schemes for Radio Access Networks (RANs) for the problem of cutting radio resources, and analyzed their advantages and disadvantages as well as applicable scenarios [15]. [PERSON] et al. proposed a dynamic slicing method for an active optical access network, which can guarantee quality of service (QoS) requirements of each user of the access network based on the QoS level of the core network [16]. [PERSON] et al. proposed a dynamic bandwidth allocation scheme for a time-division multiplexing passive optical network (TDM-PON).