Network-wide Consensus Utilizing the Capture Effect in Low-power Wireless Networks
Paper in proceedings, 2017

In low-power wireless networking, new applications such as cooperative robots or industrial closed-loop control demand for network-wide agreement at low-latency and high reliability. Distributed consensus protocols is a mature field of research in a wired context, but has received little attention in low-power wireless settings. In this paper, we present A2: Agreement in the Air, a system that brings distributed consensus to low-power multi-hop networks. We introduce Synchrotron, a synchronous transmissions kernel that builds a robust mesh by exploiting the capture effect, frequency hopping with parallel channels, and link-layer security. We build A2 on top of this reliable base layer, and enable the two- and three-phase commit protocols, as well as network services such as joining, hopping sequence distribution and re-keying. We evaluate A2 on four public testbeds with different deployment densities and sizes. A2 requires only 475 ms to complete a two-phase commit over 180 nodes. The resulting duty cycle is 0.5 percent for 1-minute intervals. We show that A2 achieves zero losses end-to-end over long experiments, representing millions of data points. When further adding controlled failures, we show that two-phase commit ensures transaction consistency in A2 while three-phase commit provides liveness at the expense of inconsistency under specific failure scenarios.

Three-phase commit


Capture effect


Group membership

Synchronous transmissions

Two-phase commit



Beshr Al Nahas

Chalmers, Computer Science and Engineering (Chalmers), Networks and Systems (Chalmers)

Simon Duquennoy

Olaf Landsiedel

Chalmers, Computer Science and Engineering (Chalmers), Networks and Systems (Chalmers)

Proceedings of the Conference on Embedded Networked Sensor Systems (ACM SenSys)


Areas of Advance

Information and Communication Technology

Subject Categories

Computer and Information Science



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