The 6TiSCH protocol stack was proposed to ensure high-performance communications in the Industrial Internet of Things (IIoT). However, the lack of sufficient time slots for nodes outside the 6TiSCH's Destination Oriented Directed Acyclic Graph (DODAG) to transmit their Destination Advertisement Object (DAO) messages and cell reservation requests significantly hinders their integration into the DODAG. This oversight not only prolongs the device's join time but also increases energy consumption during the network formation phase. Moreover, challenges emerge due to the substantial number of control packets employed by both the 6TiSCH Scheduling Function (SF) and routing protocol (RPL), thus draining more energy resources, increasing medium contention, and decreasing spatial reuse. Furthermore, an SF that overlooks previously allocated slots when assigning new ones to the same node may increase jitter, and more complications ensue when it neglects the state of the TSCH queue, thus leading to packet dropping due to queue saturation. Additional complexity arises when the RPL disregards the new parent's schedule saturation during parent switching, which results in inefficient energy and time usage. To address these issues, we introduce in this paper novel mechanisms, strategically situated at the intersection of SF and RPL that are designed to balance the control packet distribution and adaptively manage parent switching. Our proposal, implemented within the 6TiSCH simulator, demonstrates significant improvements across vital performance metrics, such as node's joining time, jitter, latency, energy consumption, and amount of traffic, in comparison to the conventional 6TiSCH benchmark.

翻译：为保障工业物联网（IIoT）的高性能通信，业界提出了6TiSCH协议栈。然而，由于6TiSCH目标导向有向无环图（DODAG）外部的节点缺少足够的时隙来传输目标通告对象（DAO）消息和信元预留请求，严重阻碍了其融入DODAG的进程。这一缺陷不仅延长了设备的入网时间，还增加了网络形成阶段的能耗。此外，6TiSCH调度函数（SF）和路由协议（RPL）使用大量控制报文所引发的挑战进一步加剧——既消耗更多能量资源，又增加了介质竞争并降低了空间复用效率。更值得关注的是，若SF在为同一节点分配新时隙时忽略先前已分配的时隙，将导致抖动加剧；而忽略TSCH队列状态时，还会因队列饱和引发丢包问题。当RPL在父节点切换过程中忽视新父节点的调度饱和状态时，更会引发额外的复杂度，导致能量与时间资源的低效利用。针对上述问题，本文提出了位于SF与RPL交叉点的新型机制，旨在平衡控制报文分布并自适应管理父节点切换。在6TiSCH仿真器中的实现结果表明，与传统6TiSCH基准方案相比，本方案在节点入网时间、抖动、时延、能耗及流量等关键性能指标上均实现了显著提升。