Wireless signals from modern communication systems such as LTE and WiFi are operated in high frequencies (e.g., GHz). If we can utilize a lower frequency like FM radio which goes further and is readily available in most of the countries, can we build a pseudo universal indoor localization system? We have studied it and showed that it has a high potential.

* Many congratulations to YeoCheon Yun! This is YeoCheon Yun's first journal publication.

IEEE TMC (Transactions on Mobile Computing, Impact Factor: 2.912) is a top-notch mobile computing journal.

[ ABSTRACT ]We present ACMI, an FM-based indoor localization system that does not require proactive site profiling. ACMI constructs the fingerprint database based on pure estimation of indoor RSS (received signal strength) distribution, where only the signals transmitted from commercial FM radio stations are used. Based on extensive field measurement study, we established our own signal propagation model that harnesses FM radio characteristics and open information of FM transmission towers in combination with the floor-plan of a building. Output of the model is an RSS fingerprint database. Using the fingerprint database as a knowledge base, ACMI refines a positioning result via the two-step process; parameter calibration and path match- ing, during its runtime. Without site profiling, our evaluation indicates that ACMI in 7 campus locations and 3 downtown buildings using 8 distinguished FM stations finds positions in only about 6 and 10 meters of errors on average, respectively.

[ The indoor FM radio signal map estimated by our system with multiple levels (from left to right) of propagation modeling. ]