Orchestra

Abstract

Time slotted operation is a well-proven approach to achieve highly-reliable low-power networking through scheduling and channel hopping. It is, however, difficult to apply time slotting to dynamic networks as envisioned in the Internet of Things. Commonly, these applications do not have predefined periodic traffic patterns and nodes can be added or removed dynamically. This paper addresses the challenge of bringing TSCH (Time Slotted Channel Hopping MAC) to such dynamic networks. We focus on low-power IPv6 and RPL networks, and introduce Orchestra. In Orchestra, nodes autonomously compute their own, local schedules. They maintain multiple schedules, each allocated to a particular traffic plane (application, routing, MAC), and updated automatically as the topology evolves. Orchestra (re)computes local schedules without signaling overhead, and does not require any central or distributed scheduler. Instead, it relies on the existing network stack information to maintain the schedules. This scheme allows Orchestra to build non-deterministic networks while exploiting the robustness of TSCH. We demonstrate the practicality of Orchestra and quantify its benefits through extensive evaluation in two testbeds, on two hardware platforms. Orchestra reduces, or even eliminates, network contention. In long running experiments of up to 72 h we show that Orchestra achieves end-to-end delivery ratios of over 99.99%. Compared to RPL in asynchronous low-power listening networks, Orchestra improves reliability by two orders of magnitude, while achieving a similar latency-energy balance.

Internet of Things: A Scientometric Review

“…Finally, RPL is discussed as an IPv6 Routing Protocol for Low-Power and Lossy Networks as a mechanism for multipoint-to-point and point-to-multipoint traffic for these kinds of networks [202]. This protocol has 78 documents with publications related to the Contiki OS and its simulator tool Cooja for WSN [203,204], and mesh networks [205][206][207].…”

TSCH and 6TiSCH for Contiki: Challenges, Design and Evaluation

“…This results in a behavior equivalent to slotted ALOHA [20]. Alternatively, we provide Orchestra [8], which is an autonomous scheduler, where nodes compute their schedule locally, based on their routing state. With Orchestra, timeslot coordinates are simply based on a hash of the node's and neighbor's MAC addresses.…”

“…We use Orchestra [8] for scheduling, with two slotframes. The first slotframe is for beacons, with length 397 and an Orchestra sender-based slot.…”

“…Our scheduler Orchestra [8] is complementary, as it provides a basic schedule that nodes can maintain autonomously, simply based on the local knowledge of their neighborhood. Orchestra can potentially be used jointly with other schedulers.…”

Dependable Interference-Aware Time-Slotted Channel Hopping for Wireless Sensor Networks

“…There is a considerable work done on increasing performance and end-to-end reliability of low-power TSCH mesh networks. This includes works on configuring and improving performance of TSCH itself such as [8,25,30,36,37], and also works that consider the layers on top of TSCH such as [12,13,18,23,24,34]. However, to meet the stringent requirements of industrial applications such as sub-second latency and reliable communications in in-vehicle networks, more work needs to be done [38].…”