Most of us sensor developers need capacities of 10 to 100s mah with expectations for recharging under 30 mins. Which is why I was interested in a recent rumor, along with a demo I heard of this past fall, that a “microbattery” company is launching a 10mah thin and small battery, complete with a wireless energy harvester to charge the battery. The company, Planar Energy Devices, already demonstrated the same battery (I think) during the Embedded Systems Conference and powered a temperature sensing network - it lasted for hours, two day straight AND they then showed no degradation at the end of the show.

Should it so complicate to order something from SUN?

anyone who knows were it could be buy here i EU land?

The open-ZB open-source toolset has been made publicly available at http://www.open-zb-net (released 24/NOV/2006) and already witnessed over 20000 visits and 800 downloads in 13 months. This toolset is being developed within the IPP-HURRAY Research Group (http://www.hurray.isep.ipp.pt), in the context of the The ART-WiSE (Architecture for Real-Time communications in Wireless Sensor networks, http://www.hurray.isep.ipp.pt/art-wise) research framework.

We have been focusing on new communication architectures and mechanisms to support large-scale embedded computing applications with critical requirements, particularly concerning timing behaviour, which will be increasingly important in emerging and future cyber-physical systems.

The ART-WiSE research framework aims at the specification of a scalable multiple-tiered communication architecture for improving the timing and reliability behaviour of WSNs. One of our major goals is relying as far as possible on existing standard communication protocols and commercial-off-the-shell (COTS) technologies – IEEE 802.15.4/ZigBee for Tier 1 and IEEE 802.11 for Tier 2.

Concerning the IEEE 802.15.4/ZigBee protocols, which show up interesting potentialities for WSNs [1, 2], we already have significant scientific and technological contributions.

We have provided methodologies to analyse and dimension star and cluster-tree 802.15.4/ZigBee networks, namely being able to compute throughput and message delay bounds for the Guaranteed Time Slot (GTS) mechanism and ZigBee Router’s buffer requirements in cluster-tree networks (e.g. [3, 4]).

We have also proposed several important add-ons to these protocols that are backward compatible, namely the following that were already implemented and validated using the open-ZB toolset:
- an implicit GTS allocation mechanism (i-GAME, [5]); this enables to improve the bandwidth utilization by several nodes sharing a GTS;
- a solution for the problem of beacon/superframe scheduling in ZigBee cluster-tree networks (the Time Division Beacon Scheduling mechanism, [6]); this enables to engineer a synchronized cluster-tree WSN, where each cluster may operate with different and low duty-cycles, thus prolonging network lifetime;
- a hidden-node avoidance mechanism (H-NAMe; under submission); this enables to eliminate hidden-node collisions in synchronized multiple cluster WSNs, leading to improved network throughput, energy-efficiency and message transfer delays.

We have developed an open-source toolset for the IEEE 802.15.4/ZigBee protocols – Open-ZB (http://www.open-zb.net) [7, 8, 2], including:
- the IEEE 802.15.4 protocol developed in TinyOS, for the MICAz and TelosB motes;
- ZigBee Network Layer functionalities for supporting synchronized multiple cluster topologies (the Cluster-Tree topology) developed in TinyOS, for the TelosB motes;
- a simulation model of the IEEE 802.15.4 protocol developed in OPNET;
- tools for timing analysis and network dimensioning.

There are some ongoing collaborations around the open-ZB protocol stack, namely with ATMEL (http://www.atmel.com), SICS (http://www.sics.se) and SSSUP (http://erika.sssup.it) to port it to their platforms. We are also the only non-USA partner in the TinyOS Network Protocol Working Group (http://tinyos.stanford.edu:8000/Net2WG), to implement a ZigBee compliant stack for TinyOS 2.0.

REFERENCES (complete list at http://www.hurray.isep.ipp.pt/art-wise):
[1] A. Koubaa, M. Alves, E. Tovar, “IEEE 802.15.4: a Federating Communication Protocol for Time-Sensitive Wireless Sensor Networks”, chapter of the book “Sensor Networks and Configurations: Fundamentals, Techniques, Platforms, and Experiments”, Springer-Verlag, Germany, pp. 19-49, January 2007.
[2] A. Cunha, “On the use of IEEE 802.15.4/ZigBee as federating communication protocols for Wireless Sensor Networks”, HURRAY-TR-070902, MSc Thesis, September 2007.
[3] A. Koubaa, M. Alves, E. Tovar, “GTS Allocation Analysis in IEEE 802.15.4 for Real-Time Wireless Sensor Networks”, 14th International Workshop on Parallel and Distributed Real-Time Systems (WPDRTS 2006), special track on Wireless Sensor Networks, Rhodes Island, Greece, April 2006.
[4] A. Koubaa, M. Alves, E. Tovar, “Modeling and Worst-Case Dimensioning of Cluster-Tree Wireless Sensor Networks”, 27th IEEE Real-time Systems Symposium (RTSS’06), Rio de Janeiro, Brazil, December 2006, pp. 412-421, IEEE Computer Society.
[5] A. Koubaa, M. Alves, E. Tovar, A. Cunha “An Implicit GTS Allocation Mechanism in IEEE 802.15.4 for Time-Sensitive Wireless Sensor Networks: theory and practice”, to be published in the Real-Time Systems Journal, Springer. This is an extended version resulting from an invitation from the TPC of the 18th Euromicro Conference on Real-Time Systems (ECRTS’06), upon selection of the best papers of the conference.
[6] A. Koubaa, A. Cunha, M. Alves, “A Time Division Beacon Scheduling Mechanism for IEEE 802.15.4/Zigbee Cluster-Tree Wireless Sensor Networks”, 19th Euromicro Conference on Real-Time Systems (ECRTS 2007), Pisa (Italy), July 2007.
***** BEST PAPER AWARD *****
[7] P. Jurcik, A. Koubaa, M. Alves, E. Tovar, Z. Hanzalek, “A Simulation Model for the IEEE 802.15.4 protocol: Delay/Throughput Evaluation of the GTS Mechanism”, 15th IEEE International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS´07), Istanbul, Turkey, October 2007.
[8] A. Cunha, A. Koubaa, R. Severino, M. Alves, “Open-ZB: an open-source implementation of the IEEE 802.15.4/ZigBee protocol stack on TinyOS”, 4th IEEE International Conference on Mobile Ad-hoc and Sensor Systems (MASS´07), Pisa, Italy, October 2007.
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