Lead Investigators:

Paul Davis, Deborah Estrin, Richard Guy, Vinayak Naik

Overview

We have started work on understanding the wireless characteristics for the GeoNet deployments and the time synchronization protocol.

Approach

The deployment environments are primarily urban areas with a lot of tall buildings, which cause the multipath effect. Also, the urban areas are populated with interfering radio due to the 802.11b wireless network, cordless telephones, and microwave ovens. The multipath effect and the interference will impact the signal quality for the GeoNet. We need to study the impact on the quality in space and time.

Since GPS reception is not guaranteed in the shadows of the buildings, we are working on a time synchronization protocol that uses 802.11b radio.

Systems/Experiments

We have instrumented the prototype GeoNet nodes with tools to measure the signal-to-noise ratio and network throughput. We have successfully used these tools in the MASE network. Our plan is to perform measurements at a variety of locations in the UCLA campus. The locations will cover gardens, curving streets, uphill and downhill roads, roads sidelines with tall buildings, etc.

We have found out that the existing implementation of the Reference Broadcast Synchronization (RBS) protocol does work for the linear network topology.

Accomplishments

After initial set of experiments, we have found that the network quality degrades significantly in the areas, which are equipped with interfering wireless networks. Similar degradation is observed when the nodes lose line-of-sight among themselves.

Future Directions

We will deploy tens of nodes in the UCLA campus for a few months to study the wireless link characteristics in detail. We will provide HTML-based interface to the wireless tools. This will facilitate experimentations. We will modify the RBS protocol to work on the linear network topology.

People

Faculty:

• Paul Davis, Geophysics, UCLA
• Deborah Estrin, Computer Science, UCLA

Staff:

• Richard Guy, CENS, UCLA
• Vinayak Naik, CENS, UCLA

Graduate Students:

• Allen Husker, UCLA