Reasearch On Key Indoor And Outdoor Positioning Technologies Based On Opportunistic Wireless Signal

With the advancement of science,wide spreading of smart devices and highly development of internet industry,location service is playing a more and more important role in people's daily lives,which used to be widely used in some more professional fields such as geological exploration and military navigation.People now can benefit a lot from these location-based-services such as ordering food,renting cars and outdoor navigation.In the indoor positioning aspect,RSS(Received Signal Strength)based indoor positioning,signal transmission characteristic based indoor positioning and dead reckoning based indoor positioning are three kinds of widely implemented indoor positioning methods.In traditional RSS based indoor positioning techniques,positioning can be generally divided into two steps.Firstly,a completed collection of wireless signal strength features around the positioning area is generally required.After that some matching algorithm is implemented to estimate the positioning result with real-time collected signal feature when positioning devices is moving in this area.This kind of methods provides good positioning precision but requires an extra exploration of the positioning area,which leads to high workload and cannot navigation in an inexperienced place.Dead reckoning based indoor positioning techniques do not need extra exploration of positioning area,they calculate the real-time position by continuous do integral calculation with inertial information collected by sensors.This kind of methods avoids extra explorations but suffers a lot from inertial drift and error accumulation,precision drops when sensors cannot guarantee a high and stable precision performance.In the outdoor positioning field,satellite based positioning and BS(Base Station)based positioning are two major kinds of outdoor positioning techniques in civilian fields.Satellite based outdoor positioning techniques are well developed and widely used,providing high precision outdoor positioning services.Satellite positioning system depends much on sensitive signal receiver and high performance positioning module,complexity and power consumption are two mainly defects.BS based positioning techniques take advantages of high density of BS in the urban region and mostly do not need to whether update positioning devices nor use any extra modules.BS based positioning methods utilize side parameters devices received when communicate with BS,including ToA(Time of Arrival),AoA(Angel of Arrival),RSS,etc.But due to multipath effect and NLOS(Non Line Of Sight)transmission,the precision is unstable and susceptible.Also,high complexity of solving these side parameters and lack of key information make this technique more an operator side technique.Based on those defects mentioned above in these indoor positioning methods,this paper proposes a dead reckoning based indoor positioning technique,which takes advantage of opportunistic wireless signal characteristics gained real-timely in the indoor positioning area and utilizes particle filter to adjust inertial drifts.Also in this paper we demonstrate an alternative outdoor positioning technique which aims at the drawback of lack of positioning information in BS based outdoor positioning.This technique utilizes ToA information from continuous single BS to finish outdoor positioning.Due to the lack of information,the precision of this method is very limited but this technique can be used at the positioning device side.