CHAPTER 1: INTERODUCTION
According to the strategy analytics, around 80% of time people kept them indoor. Either for their work or for domestic purpose, they enclosed themselves inside the building. Hence 70% of cellular and 80% of data originates from indoor . It means the location technique should be able to perform for indoor as compare to outdoor. The most accurate technique for positioning is GPS and hence nowadays all most all smart phone are equipped with GPS. GPS works by receiving signals from satellite. Whereas satellite is power limited system, it transmits a low power to MS and hence GPS signal become weaker inside the building as due to penetration loss and multipath loss. Accurate indoor location is critical in order to assist specially for public safety such as locating emergency call tracking, location base service, requires seamless and ubiquitous positioning technology in order to enable continuity of service inside building .
As GPS is power limited system thus it has low accuracy for indoor purpose, there is another way to calculate positioning of MS which is network based system. In network based system, signal transmitted between mobile phone and the network is used to determine the mobile position . Cellular Network is design to work for indoor as well. Thus it uses a high power transmitting system which includes high power transmitter and high gain antenna. In this case, low power level problem is well addressed but a significant new obstacle for location calculation is arises which is different level of building penetration loss and multipath signal loss. In urban area, the type of building and its location greatly varies. Some are modern residential, commercial, or both type and some are traditional type. The structure of those different types of building is different to each other and hence penetration loss is also different. Multipath signal are also greatly affected due to high number of building between transmitter and receiver. As there is very less chance of Line of sight (LOS) signal indoor environment hence these two factors should be well addressed in order to more accurately locate mobile.
This research has objective to find the location of Mobile user using differential path loss between three receive signal strengths by plotting hyperbola and polynomial interpolation of appropriate degree in wireless communication network.
Location of wireless user MS recently attracted significant attention around the globe. It is because of advance of E-commerce based on location based service and call from U.S. Federal Communications Commission (FCC) that passed a mandate in 1996 requiring wireless carriers to automatically provide accurate location information in a 911 emergency call. The European Union passed in 2002 a similar mandate but mobile operators a simply asked to make their best effort to obtain a good location in case of a 112 emergency call . Location based service is such type of e-commerce which use the location of wireless user and provide the value added service to that user. Hence potential theory has been researched to calculate such position.
Every research which was carried out before has its own advantage and disadvantage.
- Some are affordable to implement and some are costly to implement.
- Similarly some need major modification in software and hardware but some need a minor.
- Many of them have good accuracy in positioning outdoor mobile location but poor accuracy in indoor environment.
- Some technology can calculate location of MS in network side only or some are in handset only but some can be done in both sides as well.
This research focus on locating MS in indoor location both from network side and from handset side. It does not need change in hardware but need a new software application in MS which is a simple application hence it is cheaper.
It will use Hyperbola principle hence any symmetrical impact in Base station transmitter (BTS) signal may be discarded while computing distance to MS from BTS. Hence it may have higher accuracy. Due to hyperbola principle for any asymmetrical impact in distance calculation from BTS to MS also may be limited to the difference in error between two path losses. Then further use a technique to minimize such combined error using appropriate degree of general interpolation on the error studied which produces minimum RMSE and use a forecasted error to get adjusted with estimated distance thus produce the more accurate reference distance.