Some exciting Contiki-based research we've beeing doing at SICS lately: we increase the 802.15.4 multi-hop throughput with 900%, increase the lifetime of ZigBee networks with 900%, and present a self-monitoring mechanism that catches bugs in both hardware and software.

Dramatic 802.15.4 Throughput Increase

Approaching the maximum 802.15.4 multi-hop throughput, Fredrik Österlind and Adam Dunkels, In Proceedings of HotEmNets 2008.

Fredrik Österlind and I have developed a new packet forwarding abstraction for Contiki with which we are able to achieve a very impressive throughput with multi-hop 802.15.4: 109 kbit/s over a 6-hop network! This is about 10 times as much as what people have previously reported and is 97% of the theoretical upper bound on throughput. The reason for being so much faster than previous work is that we use the maximum 802.15.4 packet size, we use multiple 802.15.4 radio channels to avoid interference, and our packet forwarding mechanism copies packets off the critical forwarding path.

Increasing ZigBee Lifetime

Increasing ZigBee Network Lifetime with X-MAC, Pablo Suarez, Carl-Gustav Renmarker, Adam Dunkels, and Thiemo Voigt, REALWSN 2008.

Pablo Suarez did his master thesis project at SICS where he ported/reimplemented the Open-ZB ZigBee stack to Contiki and increases ZigBee network lifetime by using X-MAC instead of the always-on MAC of ZigBee routing nodes. His work shows that X-MAC incurs a ten-fold increase the network lifetime for a data collection/alarm notification ZigBee network, at the price of a slight increase in data latency.

Self-Monitoring a Key to Success

Experiences from two sensor network deployments - self-monitoring and self-configuration keys to success, Niclas Finne, Joakim Eriksson, Adam Dunkels, and Thiemo Voigt, WWIC 2008.

Niclas Finne and Joakim Eriksson have been using Contiki-based sensor networks in two military exercise operations and found that self-configuring network protocols are themselves not enough to overcome the actual problems in real-world sensor network deployments. Self-monitoring of both hardware and software components is also needed to ensure reliable operation. The paper presents an intentionally simple and effective mechanism for self-monitoring in Contiki and shows how this catches bugs and misoperations in both hardware and software.