A Kind Of Indoor Positioning System Design Based On Radio Frequency Identification (RFID) Technology

With the further development of the wireless technology, embedded system andthe Internet, people’s demand of location information is increasing, so Location-basedservice systems are increasingly attracted the attention of people. At present, GPS isthe most widely used outdoor positioning system, but the demand of people is notlimited to the outdoor environment, for example, we hope we can get the location andnavigation in outdoor environment, such as, the library, hospital, supermarket and soon. However, GPS is in the failure state in the interior due to the structure of theblock, non line-of-sight and indoor complex electromagnetic environment, so indoorlocation is still in its infancy. Some researchers had found some indoor locationmethod, such as: Infra-red positioning, Wireless local area network (LAN),Ultrasonic positioning, Bluetooth positioning, Radio frequency identificationpositioning and so on. Compared with several other indoor positioning technologies,RFID technology has the non line-of-sight, non-contact, large transmission range,high cost performance, etc. so it has become a hot research, In this thesis, the indoorpositioning system is based on RFID technology.LANDMAC system built indoor positioning system using active RFIDtechnology, and also is fairly typical of all the indoor positioning system based onRFID. It uses reference tags for positioning, positioning accuracy is high.LANDMARC systems used a lot of reference tag instead of large amount of highprice of readers. It guaranteed the positioning accuracy under the premise of reducingthe cost of the system and had become an effective solution.VIRE system was put forward to solve the shortcomings of LANDMARCsystem whose positioning accuracy rely too much on reference density of tags. VIREalgorithm introduces virtual tag to find similar maps, and improves the accuracy ofpositioning greatly. Its core idea is on the basis of no extra hardware cost, andimproves the accuracy of positioning by eliminating the impossible positions.This thesis combines the two systems’ algorithms and gives some improvements.The reference tags of LANDMARC system is placed rectangular topology, through analysis, the structure is not the best. In this thesis, the rectangular structure topologyis changed to the isosceles triangle which is also applied in the VIRE system, andimproves the method of obtaining the virtual tags’ field intensity from linearinterpolation to nonlinear interpolation. Using Matlab to model and simulate based onthe improved localization algorithm, the results show that the improved algorithm canget better positioning accuracy.