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Page Revision: 2007/06/18 20:19
A prioritized Medium Access Control (MAC) grants the right to access the medium to the computer node with the highest priority.
Such a protocol was originally created for wireline networks; Controller Area Networks (CAN) is the most known one, and is currently deployed in 700 million units.
We are transferring this idea to the wireless domain as well and exploring it to solve problems in real-time communication
and collaborative distributed computing (wireless/wired sensor networks and cyber-physical systems).
The research in prioritized MAC protocols has triggered a number of research initiatives and frameworks, listed below.
* A prioritized MAC protocol for single broadcast domains (SBD), named WiDOM-SBD;
* A prioritized MAC protocol for multiple broadcast domains (SBD), named WiDOM-MBD;
* A prioritized MAC protocol for wireless networks that that offers several channels;
* Efficient computation of aggregated quantities (such as MIN, MAX) of sensor readings;
* Dissemination of data when the topology is unknown;
* Exploiting the multi-channel capability together with a prioritized MAC protocol.
§§§EditSectionPlaceHolder§§§WiDOM
WiDOM or WiDOM-SBD is a prioritized MAC protocol for wireless networks. It is an adaptation of the dominance protocols (used in the CAN bus) to a wireless channel.
For further details, plese visit the
WiDOM webpage.
§§§EditSectionPlaceHolder§§§WiDOM-MBD
This extension to WiDOM, supports multiple broadcast domains, resolves the wireless hidden terminal problem and allows for parallel transmissions across a mesh network. Arbitration of messages is achieved without the notion of a master coordinating node, global clock synchronization or out-of-band signalling.
§§§EditSectionPlaceHolder§§§WiDOM-MC
We are exploring the development of a simple globally prioritized multi-channel medium access control (MAC) protocol for wireless networks. Such protocol should provide “hard” pre-run-time real-time guarantees to sporadic message streams, exploit a very large fraction of the capacity of all channels for “hard” real-time traffic and also fully utilize the channels with non real-time traffic when hard real-time messages do not request to be transmitted.
§§§EditSectionPlaceHolder§§§Data Aggregation
We consider a network where nodes take sensor readings, but individual sensor
readings are not the most important pieces of data
in the system. Instead, we are interested in aggregated
quantities of the sensor readings such as minimum
and maximum values, the number of nodes and
the median among a set of sensor readings on different
nodes. We exploit a prioritized medium
access control (MAC) protocol to efficiently compute aggregated quantities
of sensor readings. We aim at developing distributed algorithms that have a very low time-and
message-complexity for computing certain aggregated
quantities.
If every sensor
node knows its geographical location, then sensor
data can be interpolated with our novel distributed algorithm,
and the message-complexity of the algorithm
is independent of the number of nodes. Such an interpolation
of sensor data can be used to compute any
desired function; for example the temperature gradient
in a room (e.g., industrial plant) densely populated
with sensor nodes, or the gas concentration gradient
within a pipeline or traffic tunnel.
§§§EditSectionPlaceHolder§§§Data Dissemination
A prioritized MAC protocol can be used to efficiently disseminate data when the topology is unknown.
We study the problem of disseminating data from an arbitrary source node to all other nodes in a distributed computer system. We assume that nodes do not know the topology and that wireless broadcast is used. We propose new protocols which propagate data faster and uses fewer broadcasts.
§§§EditSectionPlaceHolder§§§WISHES
We are exploring how to use multi-channel capability together with a prioritized MAC protocol.