The IETF IPv6 over the TSCH mode of IEEE802.15.4e (6TiSCH) working group has standardized a set of protocols to enable low power industrial-grade IPv6 networks. 6TiSCH proposes a protocol stack rooted in the Time Slotted Channel Hopping (TSCH) mode of the IEEE802.15.4-2015 standard, supports multi-hop topologies with the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) routing protocol, and is IPv6-ready through 6LoWPAN. 6TiSCH has defined the missing control plane protocols to match link-layer resources to the routing topology and application communication needs. 6TiSCH has also defined a secure light-weight join processes combining link-layer security features (through Counter with CBC-MAC (CCM*)) with a secure joining procedure using the Constrained Application Protocol (CoAP). This tutorial provides a comprehensive overview of the 6TiSCH architecture and protocol suite, including the 6TiSCH Operation Sublayer (6top), the 6top Protocol (6P), and how it uses 6LoWPAN, IP-in-IP encapsulation, and RPL. This document is meant to be used both as a primer, and as a reference. It is tailored to the advanced researcher and engineer implementing and building upon IETF 6TiSCH specifications.
The convergence of operational and information technologies in the industry requires a new generation of IP-compliant communication protocols that can meet the industrial performance requirements while facilitating the integration with novel web-based supervisory control and data acquisition (SCADA) systems. For more than a decade, the industry has relied on time-slotted channel hopping (TSCH) communication technology to meet these performance requirements through standards such as WirelessHART and ISA100.11a. TSCH-based networks have proven to yield over 99.999% end-to-end reliability, supporting flow isolation and QoS management while ensuring over a decade of battery lifetime. However, these technologies were designed to address the factory use cases of a decade ago, not considering IP compliance or standardized network management and resource orchestration as a must. The Internet Engineering Task Force (IETF) and the 6TiSCH working group (WG) have been actively working on this challenge by designing protocols to bridge the performance of industrial solutions with IP-compliant networks. The effort has resulted in 6TiSCH, a set of specifications that define the IPv6 control plane to manage and orchestrate a TSCH network. 6TiSCH provides the missing elements for zero-configuration TSCH network bootstrap, efficient network access authentication, and distributed and modular scheduling mechanisms. As a cross-layer effort, 6TiSCH leverages and integrates other IETF specifications and the WG has also driven the definition of novel specifications in other IETF WGs. An ultimate goal of this effort is the definition of a fully functional architecture where a combination of IETF protocols enables the envisioned convergence on top of the IEEE industrial standard. This paper introduces the work done by the 6TiSCH WG at IETF, evaluates the performance of the reference implementation, and discusses the 6TiSCH software ecosystem.
This paper presents GreenNet, an energy efficient and fully operational protocol stack for IP-enabled wireless sensor networks based on the IEEE 802.15.4 beacon-enabled mode. The stack runs on a hardware platform with photovoltaic cell energy harvesting developed by STMicroelectronics (STM) that can operate autonomously for long periods of time. GreenNet integrates several standard mechanisms and enhances existing protocols, which results in an operational platform with the performance beyond the current state of the art. In particular, it includes the IEEE 802.15.4 beacon-enabled medium access control (MAC) integrated with lightweight IP routing for achieving very low duty cycles. It offers an advanced discovery scheme that accelerates the process of joining the network and proposes an adaptation scheme for adjusting the duty cycle of harvested nodes to the available energy for increased performance. Finally, it supports security at two levels: a basic standard secure operation at the link layer and advanced scalable data payload security. This paper describes all techniques and mechanisms for saving energy and operating at very low duty cycles. It also provides an evaluation of the performance and energy consumption of GreenNet.
RPL, the routing protocol proposed by IETF for IPv6/6LoWPAN Low Power and Lossy Networks has significant complexity. Another protocol called LOADng, a lightweight variant of AODV, emerges as an alternative solution. In this paper, we compare the performance of the two protocols in a Home Automation scenario with heterogenous traffic patterns including a mix of multipoint-to-point and point-to-multipoint routes in realistic dense non-uniform network topologies. We use Contiki OS and Cooja simulator to evaluate the behavior of the ContikiRPL implementation and a basic non-optimized implementation of LOADng. Unlike previous studies, our results show that RPL provides shorter delays, less control overhead, and requires less memory than LOADng. Nevertheless, enhancing LOADng with more efficient flooding and a better route storage algorithm may improve its performance.