Demo abstract: Signal reconstruction with subnyquist sampling using wireless sensor networks
IPSN '09 Proceedings of the 2009 International Conference on Information Processing in Sensor Networks
Profiling primitives of networked embedded automation
CASE'09 Proceedings of the fifth annual IEEE international conference on Automation science and engineering
Low-complexity perceptual packet marking for speech transmission over tiny mote device
ICME'09 Proceedings of the 2009 IEEE international conference on Multimedia and Expo
High-resolution speech signal reconstruction in wireless sensor networks
CCNC'09 Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference
Information Sciences: an International Journal
Analysis of audio streaming capability of Zigbee networks
EWSN'08 Proceedings of the 5th European conference on Wireless sensor networks
Non-intrusive aggregation in wireless sensor networks
Ad Hoc Networks
Analysis of buffer size dimensioning in GTS enabled IEEE 802.15.4 WSN for real-time applications
International Journal of Mobile Network Design and Innovation
Adaptive real-time query scheduling for wireless sensor networks
Proceedings of the 14th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems
Building a low cost low power wireless network to enable voice communication in developing regions
ACM SIGMOBILE Mobile Computing and Communications Review
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Wireless sensor networks have traditionally focused on low duty-cycle applications where sensor data are reported periodically in the order of seconds or even longer. This is due to typically slow changes in physical variables, the need to keep node costs low and the goal of extending battery lifetime. However, there is a growing need to support real-time streaming of audio and/or low-rate video even in wireless sensor networks for use in emergency situations and shortterm intruder detection. In this paper, we present FireFly, a time-synchronized sensor network platform for real-time data streaming across multiple hops. FireFly is composed of several integrated layers including specialized low-cost hardware, a sensor network operating system, a real-time link layer and network scheduling which together provide efficient support for applications with timing constraints. In order to achieve high end-to-end throughput, bounded latency and predictable lifetime, we employ hardware-based time synchronization. Multiple tasks including audio sampling, networking and sensor reading are scheduled using the Nano- RK RTOS. We have implemented RT-Link, a TDMA-based link layer protocol for message exchange on well-defined time slots and pipelining along multiple hops. We use this platform to support 2-way audio streaming concurrently with sensing tasks. For interactive voice, we investigate TDMA-based slot scheduling with balanced bi-directional latency while meeting audio timeliness requirements. Finally, we describe our experimental deployment of 42 nodes in a coal mine, and present measurements of the end-to-end throughput, jitter, packet loss and voice quality.