Technique finds gaps in wireless networks

Rooting out Wi-Fi 'dead zones' in large wireless networks that cover whole neighbourhoods or cities is an expensive proposition. Pre-deployment testing is so costly that most Wi-Fi providers simply build their networks first and fill in the gaps later. But that isn't easy, due to the paucity of inexpensive techniques for mapping out precisely which areas lack coverage.

Now, thanks to a technique developed at Rice University and Hewlett-Packard Laboratories (HP Labs), Wi-Fi architects can test and refine their layouts using readily available information. The research, which won best-paper honours at the annual MobiCom '08 wireless conference in San Francisco, claims to make it cheaper and easier to get proper wireless coverage.

"In the real world there are many things than can interfere with signals and limit coverage," said lead researcher Edward Knightly, professor in electrical and computer engineering at Rice.

"Our goal was to efficiently characterise the performance of urban-scale deployments, and our techniques can be used to either guide network deployment or to assess whether a deployed network meets its performance requirements."

The technique uses a small number of measurements to predict how well a wireless transmitter will cover a particular portion of a neighborhood. The only information required is basic topography, street locations and general information about land use.