Indoor Location Research Based On Fingerprint And PDR

With the development of mobile Internet, the location of mobile device technology attracts considerable attention. The Global Position System(hereinafter GPS),which cannot penetrate obstacles, can’t meet the demands of indoor location. However, indoor location is indispensable in some areas, such as large shopping malls, hospitals, warehouses, large parking lot and etc.Indoor location based on Wi Fi, which has a high rate of penetration、low cost and simple implementation, has become more and more popular in recent years. Fingerprint location algorithm is a representative algorithm of indoor location based on Wi Fi. Pedestrian Dead Reckoning(hereinafter PDR) is a typical algorithm of Inertial measurement which is based on acceleration sensor, electronic compass and other sensors.This paper investigates the key influence factors of fingerprint indoor location, such as signal strength influenced by people, correlation of different APs, signal strength with change of distance, and lays its emphasis on researching the most important factor——AP selection algorithm.Most of AP selection algorithms work in offline or online phase which neglects time-varying characteristic. This defection leads to expired of fingerprint database and low precision. This paper proposes an AP selection algorithm based on discrimination which works in offline and online phase. Experiments demonstrate that AP selection based on discrimination had a higher precision than Max Mean AP selection algorithm.This paper mainly makes some improvements for the defection of step model which has a low accuracy when user walking at different speed. Experiments show that the improved step model has a high accuracy while user walking at various speed.Fingerprint indoor location algorithm has some drawbacks in terms of accuracy affected by environment.PDR algorithm has a variety of disadvantages, such as accumulative error and can’t work without initial position. This paper proposes fusion indoor location algorithm based on fingerprint and PDR. On the one hand, it not only reduces time and space complexity of fingerprint algorithm but also enhances the robustness to the environment. On the other hand, PDR’s result can be revised by fingerprint and accumulative error can be decreased.Finally, fusion indoor location system based on fingerprint and PDR is designed and programmed. Experiments indicate that fusion indoor location algorithm not only has a higher accuracy than fingerprint but also improves the robustness to the environment.