Welcome to FlockLab

FlockLab is a wireless sensor network (WSN) testbed, developed and run by the Computer Engineering and Networks Laboratory at the Swiss Federal Institute of Technology Zurich in Switzerland supported by the National Competence Center in Research on Mobile Information and Communication Systems.

Quick Overview / Executive Summary

A vital factor for a successful deployment of sensor nodes is testing of all system aspects in a realistic setup. FlockLab introduces a testbed architecture which allows for detailed monitoring and stimulation of wireless sensor nodes. In particular, time-accurate state extraction and power measurements are provided in a distributed, yet synchronized context.
For general embedded systems, testing the software and the system’s power consumption relies on expensive lab instruments such as logic analyzers and oscilloscopes. FlockLab brings the functionalities of these tools into a distributed context for detailed testing of a sensor network. This is achieved by pairing a sensor node with dedicated hardware for monitoring and stimulation. Different services such as measuring power consumption and time accurate pin monitoring and setting are provided to the tester. By reducing accuracy of measurements to a sufficient level (e.g., tens of microseconds temporal granularity across nodes), costs are significantly reduced to enable an affordable distributed lab instrument. Hence, in difference to previous testbeds, which only allowed for detailed measurements on individual nodes, numerous nodes can be observed in detail.
Unlike most testbeds which allow only for one type of wireless sensor node to be connected, FlockLabs flexible hardware interface offers 4 target adapter slots to which arbitrary sensor nodes can be attached. Currently there exist target adapters for Tmotes, TinyNodes, Opal nodes and MEMSIC Iris nodes.

FlockLab's key features include:

  • FlockLab's observer based testbed architecture which provides services for detailed testing of sensor nodes:
    • Time accurate pin monitoring
    • Time accurate pin setting
    • Power measurements
    • Serial interface logging
    • Voltage control to simulate e.g. battery depletion
  • Flexibility to attach up to 4 arbitrary wireless sensor nodes over a generic hardware interface.
  • Network-wide programming and configuration of testbed and sensor nodes.
  • The testbed architecture seamlessly merges data from all services into a consistent global view:
    • All services have a common, high-precision time base
    • Data taken from all sensor nodes is directly comparable due to common time base between nodes
    • All test data is kept in a single database
  • High-speed, flexible and reliable backbone for out-of-band extraction of data.
  • Testbed consisting of 30 observers organized in a mixed indoor/outdoor topology.
  • Excellent scalability and flexibility due to FlockLab's 3-tier-architecture.

FlockLab is available for the research and development community. Contact us for more information.

FlockLab Architecture

3_tier_architecture.png FlockLab is designed in a 3-tier-architecture. The lowest tier is the so called system layer which consists of sensor nodes which build the actual wireless sensor network which shall be tested. The sensor nodes build a communication network as they would in a real deployment. To each sensor node, a second, more powerful node is attached, the so called observer node. The observer nodes are based on a small computer which runs Linux (see the hardware specifications for more details) and communicate over LAN or WLAN. They build the second tier (observation layer) which provides all services and efficient means for out-of-band extraction of data avoiding interference with the system layer.
The third and final tier is a dedicated server to which all observer nodes connect. The server is responsible for the distribution of configurations to the nodes, starting and stopping test runs and collecting, analyzing and displaying test data to the tester. Furthermore, the server acts as a local time synchronization server to which all observer nodes synchronize their local time.

FlockLab's approach with a 3-tier-architecture allows for increased flexibility and independence of all tiers. Each tier is designed to be independent of the others and to introduce as low interference as possible to the wireless sensor network under test.

ArchitectureMinimal.png The connection between sensor nodes and observer nodes is accomplished over an attached interface board. Apart from standard functionalities for logging over a UART or programming, this interface provides access to GPIO pins and means for voltage control and power measurements.

FlockLab provides several services on the observer for using these interfaces for testing. These services include timed setting or monitoring of GPIO pins, controlling the serial port e.g., via the TinyOS or Contiki serial forwarder, and taking power measurements. GPIO pin monitoring and setting provide distributed logic analyzer capabilities. In particular, these services are accurately synchronized within tens of microseconds across all nodes. Distributed voltage control and power profiling enable elaborate power consumption analysis under differing operating conditions.

Hardware

An observer which is built of a Gumstix Linux computer and an interface board can host up to 4 different wireless sensor nodes over a generic hardware interface. The hardware can be seen in the picture on the right with attached sensor nodes on 3 out of 4 slots. observer_indoor_4.jpg

Sensor nodes

The sensor nodes currently attached to the testbed are:

  • TinyNode184 from Shockfish SA. The key features of these nodes are:
    • 16MHz Texas Instruments MSP430 microcontroller (MSP430F2417)
    • 868 / 915MHz Semtech SX1211 ultra-low power wireless transceiver
    • 512kB external flash
    • On-board chip antenna, footprint for SMA/MMBX connector

More information about the TinyNode184 can be found here.

  • Tmote Sky (TelosB) from Moteiv:
    • 8MHz Texas Instruments MSP430 microcontroller (MSP430F1611) with 10k SRAM, 48k flash and 1024k serial storage
    • 250kbps 2.4 GHz Chipcon CC2420 IEEE 802.15.4 Wireless Transceiver
    • On-board chip antenna, footprint for SMA connector
    • On-board humidity, temperature and light sensors

More information about the Tmote Sky can be found here.

observer_outdoor_1.jpg

  • Opal nodes from CSIRO. More information about the node can be found here
  • Iris (MicaZ) motes from MEMSIC with IBM Moterunner:
    • 16MHz Atmel AVR ATmega1281 microcontroller with 8K RAM, 128K program flash and 512K serial flash
    • 250kbps 2.4 GHz Chipcon CC2420 IEEE 802.15.4 Wireless Transceiver

More information about the Iris mote can be found here.

Other sensors can be attached to the testbed easily due to FlockLabs generic hardware interface. Contact us for more information.

Observer nodes

The observer nodes are built of a Gumstix computer and an interface board. The latter was especially designed at our laboratory for FlockLab. The key features of the Gumstix computer are:

  • Gumstix verdex pro XL6P
  • 600 MHz PXA270 processor
  • 32 MB flash
  • 128 MB RAM
  • Attached 8GB microSD card for data storage

The interface board features:

  • 4 generic hardware interface slots to attach any kind of wireless sensor node with a simple adapter board
  • RTC with battery backup (keep date and time over power cycles)
  • Voltage and current measurements on-board

More information about the observer nodes can be found in the Wiki.

Software

Sensor nodes

FlockLab users can program the nodes with a choice of:

  • TinyOS (FlockLab supports TOS node ids as well as TOS messages)
  • Contiki (FlockLab supports node ids as well as SLIP packages)
  • Any programming of choice

Observer nodes

The observer nodes run openembedded Linux, currently with kernel version 2.6.33.

Deployment

http://flocklab-server01.ethz.ch/zabbix/map.php?sysmapid=3 The current deployment consists of 30 observers and 1 server which are spread across one level of the ETZ-building at ETH Zurich and the surrounding rooftops. As a backbone network, LAN and WLAN are used.

Publications

Contact

  • Email: flocklab(at)tik.ee.ethz.ch
  • Website: http://www.flocklab.ethz.ch
  • Physical address:
    ETH Zurich
    Computer Engineering and Networks Laboratory (TIK)
    Gloriastrasse 35
    CH-8092 Zurich
    Switzerland