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Voice Over Sensor Networks
Real-Time and Embedded Systems Lab (mLAB)
  • Rahul Mangharam, University of Pennsylvania
  • Anthony Rowe, Carnegie Mellon University
  • Raj Rajkumar, Carnegie Mellon University
  • Ryohei Suzuki, Tokyo Denki University
Document Type
Conference Paper
Date of this Version
Suggested Citation:
R. Mangharam, A. Rowe and R. Rajkumar, "Voice over Sensor Networks" 27th IEEE Real-Time Systems Symposium (RTSS), Rio de Janeiro, Brazil, December 2006.

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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 describe a real-time voice stream-capability in wireless sensor networks and summarize our deployment experiences of voice streaming across a large sensor network of FireFly nodes in an operational coal mine. 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. We are able to provide efficient support for applications with timing constraints by tightly coupling the network and task scheduling with hardware-based global time synchronization. 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.

  • Scheduling Algorithms for Embedded Wireless Networks
Citation Information
Rahul Mangharam, Anthony Rowe, Raj Rajkumar and Ryohei Suzuki. "Voice Over Sensor Networks" (2006)
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