Thrifty Tracking: Smooth and Accurate Online GPS Tracking with Low Data Uplink Utilization
An online GPS tracking system typically consists of a GPS-equipped mobile device, a wireless uplink, a receiving server and a final trace consumer. A trade-off exists between the accuracy of the location perceived by the final consumer, and the cost incurred at the uplink, or “data usage” in current industry terms. Intuitively, we may reduce data usage by transmitting fewer reports over the uplink, at the cost of reducing accuracy at the consumer.
We present an end-to-end framework for improving the cost efficiency of online GPS tracking systems. Here, we consider one system more efficient than another if it offers improved accuracy at the same cost, or lower cost at the same accuracy. We implement 46 potential thrifty tracking methods, and evaluate these on a collection of GPS traces comprising 1,200 hours of data from 1,000 individuals, for a total of 3.6 million GPS points.
We also perform experiments to characterize the data usage billing policy of a major wireless provider. We find that depending on the the protocol used, bytes of data usage billed per transmission can be up to 1200 the actual bytes of data sent, underscoring the importance of data efficiency.