# Efficient Route Management Method for Mobile Nodes in 6 TiSCH Network
## 2 Background
### Tsch
A centralized scheduling scheme allows a node to have link information related to the entire network and manages the schedule of the network. The TASA technique proposed in [18] proposes a pattern-and-topology-aware scheduling technique for traffic. However, while these centralized scheduling techniques can theoretically achieve better performance, real-world implementations have the disadvantage of incurring a large number of control messages overhead, resulting in lower scalability of the network. Distributed scheduling methods provide higher scalability using protocols that negotiate cells between nodes. Therefore, it is an algorithmic method suitable for dynamic or large networks. There is one representative distributed scheduling technique with minimal scheduling function (MSF) presented by six TiSCH WG. This algorithm makes it possible for two neighboring cells to be added/deleted by negotiating 6P to allow two neighboring nodes to add/delete/replace cells in the TSCH schedule. Two adjacent nodes negotiate the location of the cells to be added, deleted, or relocated in the TSCH schedule. This negotiation process is called a 6P transaction, which consists of two or three stages. This scheduling technique does not have an algorithm to support moving nodes and repeats the process of moving nodes to build routing paths. Ref. [19] proposed BOOST, a protocol that combines TSCH MAC with opportunistic routing and scheduling. Based on layer ID (LID), which is the distance (hop number) from the root node, this protocol determines which channels should be sent or received. The node that wants to send data to the mobile node sends a request message in advance before sending data and sends data packets only to the response node. This achieves 99.99% stability in packet transmission success rate to moving nodes. The Orchestra scheduling technique [20] is an information-based scheduling method for RPL. Using its own MAC address-based hash function, the slot offset of a dedicated cell is determined without the signal overhead. It features separate slot frames for EB in TSCH, control messages in RPL, and data frames for the independent use of slot frames. It quickly responds to sudden changes in topology without the process of cell negotiation between two nodes, can use RPL to respond to changes in the network, and can take advantage of TSCH's robustness, reducing end-to-end latency and packet queue length. Studies exist on scheduling techniques for TSCH standards for moving nodes. In [21], the authors supported node mobility in industrial wireless sensor networks through software-defined network architecture. The architecture of [21] requires a fixed link schedule, and each moving node presents a technique for assigning at least one link to form a fixed link schedule that communicates with each stationary node. However, there is  
Figure 2: TSCH slot frame and topology. a disadvantage in reducing network scalability by supporting only a limited number of nodes by forming a fixed link schedule for stationary and moving nodes. The author of [22] proposed MTSCH and introduced the manual enhanced beacon concept to quickly engage mobile nodes in the network. Rather than listening to the EB broadcast in the last time slot of the existing slot offset, it was able to reduce the latency of synchronization messages and save energy compared to the existing TSCH, listening to specific messages only on fixed channels. In addition to scheduling techniques for the TSCH protocol for moving nodes, there has also been an investigation into the stability of the network with the presence of moving nodes. In [23], the authors analyze the effects of mobility on stability in terms of synchronization, message overhead, latency, and energy. Experimental results show that if the topology configuration of static nodes in the network is not fully covered, the loss during the synchronization process prevents the moving nodes from connecting to the network for a long time, which can cause significant downtime in the network.