Page History: Publications

Björn Andersson, Nuno Pereira and Eduardo Tovar
IPP-HURRAY Technical Report - TR-061102
Nov. 2006 [pdf]

Consider a wireless sensor network where all nodes share a single broadcast domain. Sensor nodes take sensor readings but individual sensor readings are not very important. It is important however to compute aggregated quantities of these sensor readings. We show that a prioritized medium access control (MAC) protocol for wireless broadcast is useful for efficiently computing aggregated quantities. We present algorithms for computing aggregated quantities with a time complexity that is independent of the number of sensor nodes. We present algorithms for computing MIN and MAX and propose approximation algorithms for COUNT and MEDIAN. We show that if every sensor node knows its geographical position, then sensor data can be interpolated and the time complexity of this interpolation algorithm does not depend on the number of sensor nodes. Such an interpolation of sensor data can be used to compute any function desired; for example, the temperature gradient in a room densely populated with sensor nodes.

Björn Andersson, Nuno Pereira and Eduardo Tovar
5th Intl Workshop on Real Time Networks (RTN'06)
2006 [pdf]

Consider a distributed computer system such that every computer node can perform a wireless broadcast and when it does so, all other nodes receive this message. The computer nodes take sensor readings but individual sensor readings are not very important. It is important however to compute the aggregated quantities of these sensor readings. We show that a prioritized medium access control (MAC) protocol for wireless broadcast can compute simple aggregated quantities in a single transaction, and more complex quantities with many (but still a small number of) transactions. This leads to significant improvements in the time-complexity and as a consequence also similar reduction in energy "consumption".