Mitigating GPS Error in Mobile Environments

We study the problem of accurately determining the position of a mobile device using imprecise off-the-shelf GPS devices. Existing work has not yet explored the impact of mobility on GPS error for off-the-shelf devices. We demonstrate that a naive use of GPS in mobile situations can lead to significant errors. Based on both stationary and mobile vehicular experiments, we identify four distinct sources of measurement error, resulting in a surprising 49.0 m of error while traveling at highway speeds of 100 km/h. We quantify the error into systematic error (44.7 m) and random error (4.3 m). We also show how simple techniques can significantly reduce systematic error, yielding up to a ten-fold reduction of error in mobile GPS measurements. We find that mobile error is primarily caused by misreporting when position measurements were taken and infrequent measurements. After correcting for these errors, off-the-shelf devices can be used for accurate position measurement while mobile.