Image   Prioritized Medium Access Control


Modified: 2008/05/29 18:50 by npereira - Categorized as: Introduction
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.



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.



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.

For further details, plese visit the WiDOM-MBD webpage. Edit


We are also exploring the development of a simple globally prioritized multi-channel medium access control (MAC) protocol for wireless networks. Such a 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.

For further details, you are referred to our RTN'07 paper. Edit


We have been using CAN for efficient distributed computation of aggregated quantities. The use of such a prioritized MAC protocol is proposed to be in a way that priorities are dynamically established during runtime as a function of the sensed values involved in the specific distributed computation.

For further details, plese visit the WiSe-CAN webpage. Edit

Exploiting Prioritized MAC for Data Aggregation and Data Dissimination

In a dominance-based MAC protocol the computer node contending with the highest priority (lowest number) is granted access to the medium. This election procedure can also be used to compute the minimum value of sensor readings distributed on different computer nodes and, remarkably, this computation can be performed with a time-complexity that is independent of the number of computer nodes. This procedure forms an important building block for other useful calculations; for example, it is possible to efficiently extract an interpolation of sensor readings and this can be performed with a time-complexity that is independent of the number of computer nodes. This is a crucial asset for addressing problems in future Large-Scale Dense Sensor Networks for Cyber-Physical Systems (CPS).

For further details, plese visit the Data Aggregation webpage.

A prioritized MAC protocol can be used to efficiently disseminate data when the topology is unknown. We are studying the problem of disseminating data from an arbitrary source node to all other nodes in a distributed 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.

Concerning exploring priorities for data dessimination, please take a look to this paper.


A Platform for Scalable Aggregate Computations in Cyber-Physical Systems

Based on the principle above (exploiting a prioritized MAC protocol for data aggregation), we address the problem of enabling such approaches in the wireless domain.

The main contribution of this research is a novel hardware/software architecture that proves to be efficient (low overhead, and low energy consumption) for supporting aggregate computations in wireless systems.

More details are provided here.

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