Research On The Second Position Algorithm Based On GIS In LCS

The wireless localization service is called Location-Based Services(LCS), isan value-added service provided by mobile communications network, obtains thelocation information of mobile subscriber(for example latitude and longitudecoordinates data) through some location technologies, provides for mobilesubscriber or other people as well as the communications system, realizes eachkind of the location relatives services. "Chinese Location-based Service MarketAnalysis" reported by Bo Tong Zhi Xin which is dedicated in telecommunicationconsultation indicated that the Chinese LCS service will enter the high speedgrowth phase in 2006 the second half year. The report thinks that the main reasonsof the location service development so slow are that the LCS service technology,the content all quite complex, operation business and the SP preparation areinsufficient, and faced with various development barrier, the cognition, the content,the technology, the terminal, the privacy, the backstage, cooperates and roams andso on.This paper divides the LCS service correlation technology into three parts:Position technologies based on the mobile network, the core network sideimplementation technology about LCS services and the location service providerside implementation technology about LCS services. Through contrast currentpositioning accuracy and LCS service demand, no matter which one localizationmethod uses, the mobile network all cannot guarantee stably provides real-time andprecise location information. Along with the development of LCS servicesgradually, some service required high precise location information will be neededmore precise requirement inevitably. Like the position accuracy which needed bynavigation or track services is 30 meters and the system corresponding time in 5seconds. There are two methods solve this problem, one method is that from accessnetwork side and the core network side adopts more precise position technology,but there is no feasible solution currently. Another solution is that joins a secondposition module in GIS engine in SP side, which function is implements mapmatching. The core of this paper is just the second positioning algorithm.So far, there have been many mobile positioning methods. For example: TA,TOA, E-OTD, A-GPS, OTDOA and so on. TA, TOA, E-OTD and A-GPSpositioning technologies in core network side implementation have beenstandardized in 3GPP TS03.71. This paper has carried on the detailed investigationto several positioning technologies performance index and the applicable scope,after that, this paper also conducts the detailed research to the LCS service structurein core network side, including with the positioning operation related entities(e.g.GMLC, SMLC, LMU and so on) and its corresponding basic function, specifyvarious function entities' standard interface, specially, the interface Le betweenLCS Client and LCS Server, and the specific data provided by LCS Server in corenetwork side to LCS Client in SP side. The standard protocol Le interface is MLPprotocol standardized by OMA.The GIS relative technologies are indispensable implementation technologiesin the LCS service, GIS buffer technology may be well applied into map matchingalgorithm, it can determine geography information within certain distance to somespot, line or in the surface in buffer. This paper is just uses the GIS buffer to judgethe located object running road using map matching algorithm to the roads inrelative error area. Because both the electronic map and the position data have theerror, before introduce of self-adaptive fuzzy decision algorithm based on GISbuffer, this paper studied how to determine the relative error between the firstposition data and the electronic map detailedly.This paper introduces a self-adaptive fuzzy decision algorithm based on GISbuffer. Candidate matching roads information is stored in GIS buffer. Whenjudging the matched road of the current matching point, previous candidatematching information is used to enrich the current judging information. Though themoving object in the area of road crossing point or intensive highway, thealgorithm can reach high accurate still. Through self-adaptive adjusting and fuzzydecision, the algorithm advances the differentiation degree between the right roadand wrong. We can judge the matched road immediately, so it is a real-timealgorithm. The processes of selecting candidate matching roads and matchingcomputation are almost in GIS Buffer, so the computing complexity of thisalgorithm is reduced.Finally, this paper also has a rough research to the specific implementation inLCS service provider side, and produces a second position middleware modelcombine this paper algorithm. From the demand analysis about the second positionfunction, this paper gives the second position middleware's position in GIS engine,also has determined the module partition in the second position middleware modelas well as each module function, here this paper also proposed the timer strategywhich can guarantee real time of the algorithm. Because the current the GISproduct interface, the standard provided by GIS merchant are inconsistent, thispaper only displays the data structures and some core function needed by thealgorithm in the fifth chapter.