SCADDS: Scalable Coordination A rchitectures for Deeply Distributed Systems

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Sensor-MAC (S-MAC): Medium Access Control for Wireless Sensor Networks

S-MAC is a medium-access control (MAC) protocol designed for wireless sensor networks. Wireless sensor networks use battery-operated computing and sensing devices. A network of these devices will collaborate for a common application such as environmental monitoring. We expect sensor networks to be deployed in an ad hoc fashion, with individual nodes remaining largely inactive for long periods of time, but then becoming suddenly active when something is detected. These characteristics of sensor networks and applications motivate a MAC that is different from traditional wireless MACs such as IEEE 802.11 in almost every way: energy conservation and self-configuration are primary goals, while per-node fairness and latency are less important.

S-MAC uses three novel techniques to reduce energy consumption and support self-configuration. To reduce energy consumption in listening to an idle channel, nodes periodically sleep. Neighboring nodes form virtual clusters to auto-synchronize on sleep schedules. Inspired by PAMAS, S-MAC also sets the radio to sleep during transmissions of other nodes. Unlike PAMAS, it only uses in-channel signaling. Finally, S-MAC applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data move through the network. We evaluate our implementation of S-MAC over a sample sensor node, the Mote, developed at University of California, Berkeley. The experiment results show that, on a source node, an 802.11-like MAC consumes 2--6 times more energy than S-MAC for traffic load with messages sent every 1--10s.

Update 2012: page is superceeded, see I-LENSE for current information about S-MAC and more recent protocols.



Update 2012: page is superceeded, see the I-LENSE publications for current information about S-MAC and more recent protocols like SCP-MAC.



We have implemented S-MAC on the Mica Motes running TinyOS . However, our implementation is not based on the standard radio communication stack in the TinyOS release. Instead, we have developed a new communication stack that provides more features to allow protocols at different layers can be easily built.

The source code is now released and availble for download at here .

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Last updated on  Oct. 2, 2002 by Wei Ye .