I. Introduction
The wireless positioning service is also known as location service (LBS), is a value-added service provided by the mobile communication network, and the location information of the mobile station is obtained by a set of positioning techniques (such as latitude and longitude coordinate data). Give mobile users or others
And communication systems, implement various position-related business. Narrowly, the LBS service is a wireless value-added service of the wireless user by wireless communication network, providing a wireless value-added service of the corresponding service with the support of the geographic information system platform. In general, as long as the location-based information service belongs to the location service, some services may be independent of the location of the user itself, such as the weather of the fixed location, and the bus route between the starting point is fixed. However, in the mobile communication network, the LBS service application should be closely related to the location of the terminal holder itself.
At present, the telecom industry is fierce, mobile operators are constantly looking for new ways to create new profit points or profit growth points. Among the various mobile value-added services, the mobile location information service is one of the most market potential. On the other hand, as my country's private auto market is growing, there will be great development potential with the needs of automobile mobile communication platform, which is a market for automotive navigation and tracking, which is a very development and potential market.
For the wireless positioning service, the position service is developed on the traditional second-generation wireless communication network. Since the second-generation system data transmission capacity is low, the type of positioning service that can be provided is also limited. The data transmission capacity of the 3G system is greatly improved than the 2G system. In order to provide users with a guarantee of network bandwidth, some positioning services larger than some information is possible, such as the map display, Real-time navigation, even 3D map services, etc. A variety of types of LBS services can be divided into different classification methods as follows:
(1) divide by business request
· PULL class LBS service: mobile terminal requests LBS using short messages, WAP access, etc.
· Push class LBS service: The network actively pushes information to the mobile terminal according to a specific condition.
(2) Press whether to divide with user location
· LBS related to the user's location needs to be positioned;
· LBS-independent of the user location, no need to position.
(3) division according to user-oriented users
· Level market - public application;
· Vertical Market - Industry Application.
(4) Division of positioning service functions in the GIS system
· Map service, including raster maps and vector maps;
· Path search, including shortest path query, bus line query, etc .;
· Geographic coding / reverse geocoding;
· Measurement.
Second, realize network architecture of LBS applications
In the 3G system, the network model for implementing the LBS application is shown in Figure 1. As can be seen from Figure 1, implementation of the LBS service involves multiple entities.
Figure 1 Network architecture for implementing LBS applications in 3G systems
(1) Positioning the operation platform. The location information of the mobile station is obtained by various positioning techniques.
(2) LCS middleware. Provide a positioning service interface to the SP, SP access to the operator's positioning resource (GIS) through the LCS middleware, and completing the fees, management of the LBS service.
(3) GIS system. Provides a variety of LBS-based geographic information services, including map services, path search, directory queries, etc.
(4) SP. LBS services are provided for end users.
(5) CP. The CP specifier referred to herein provides content providers of electronic map data, POI (points of interest).
(6) Terminal. It is necessary to complete the positioning operation with the network interaction (get terminal latitude and longitude), and the final service is interacted with SP through WAP / Java / Brew / SMS. For vector map services, the terminal requires a built-in vector map browser.
For mobile network operators, in order to better carry LBS services, we need to build a positioning operation platform. For the GIS system, you can implement it yourself yourself by SP / CP, but the development of the GIS system based on LBS mode is just the beginning, so it is relatively large by SP / CP. And the resource is also a waste of resources by the SP / CP, so that the construction of the operator is constructed including the LCS middleware and the GIS system, which will play a lot of promotion of LBS applications. Third, positioning technology
The positioning operation platform is mainly responsible for obtaining the latitude and longitude information of the terminal through various positioning techniques. Currently, the positioning techniques available for mobile networks are varied, and the positioning techniques implemented on the CDMA2000 system will be described as an example to introduce various positioning techniques.
1 network-based positioning technology
In the CDMA system, in order to achieve soft switching, the mobile station is required to locate the signal from other base stations while receiving the signal of the current service base station. If the signal from other base stations is found to be strong, the mobile station needs to determine the time difference from the different base station signals, and prepare for the two signals. This capability of the mobile station lays a technical foundation for achieving positioning. The positioning operation platform can be positioned by the CDMA network to acquire this information (pilot intensity information) for the terminal. Other network-based techniques can provide higher positioning accuracy, such as measuring loop delays in the mobile station, signal arrival angle, etc., but these techniques need to increase corresponding measurement equipment on the base station, high cost.
2 auxiliary
GPS Technology (AGPS)
Assist
GPS technology is mainly relying
GPS satellite completes the positioning operation. The mobile station needs to receive at least 4
The signal of the GPS satellite, based on this information, completes the positioning calculation, and reports the calculation result to the network. In general
GPS positioning technology, need
GPS receiver search can be used in the entire space domain
GPS satellite. Usually this search takes a long time, so you can't meet the needs of fast moving positioning. In auxiliary
In the GPS technology, the network can determine the cell over the cell according to the cell where the mobile station is currently located.
GPS satellites provide this information to the mobile station. According to this information, the mobile station narrows the search process, shorten the search time, and completes the search process of the available satellite faster. After the search is complete, the mobile station needs to pass the interaction of the network, and the information used to calculate the location of the mobile station is transmitted to the network, and the location of the mobile station is calculated by the network.
3 mixed positioning technology
The mixed positioning techniques used in the CDMA system mainly use two mobile stations based on the mobile station mentioned. Generally speaking,
GPS technology provides high positioning accuracy, but in many cases, mobile stations cannot capture enough
GPS satellite. At this time, the mobile station can use the signal of the base station to supplement the insufficient satellite. This increases availability under conditions that reduce a certain precision, and realize indoor positioning.
4 based on the mobile station
GPS positioning
For some LBS services that require fast continuous positioning (eg real-time dynamic car navigation), you may require a refresh location information every few seconds. In this case, the AGPS method is difficult to meet the time requirements. Therefore, in order to improve the positioning interval during continuous positioning, the mobile station is proposed.
GPS positioning. Unlike AGPS, based on mobile station positioning mode, the calculation of the location is completed by the terminal, and the terminal is always at
GPS tracking status reduces the interaction time with the network. However, the initial positioning time (TTFF) is basically the same as the AGPS mode, like AGPS, needs to get from the network side
GPS satellite information.
Fourth, GIS system
The key core in the LBS service is the location and geographic information, and the two complement each other, it is not possible. A latitude latitude position does not mean any meaning. It must be placed in a geographic information to represent a location, flag, orientation, etc., can be understood. Therefore, in addition to the location of the terminal by the positioning operation platform, the latitude latitude must be converted into the user's truly care, such as the map, path search results, and the like. For wireless operators, how to develop SPs for end users is the key to any value-added service development. For the majority of SPs, it is not understood to the key technologies related to location information services - the Geographic Information System (GIS). From the technical point of view, SP independently provides location information services. Because I need to consider the positioning gateway interface of how to use the wireless operator, consider what kind of geographic information system considers what kind of map database, consider how to maintain the map database, consider how to develop, how to promote the market Development makes more users to join their operating networks. For the above consideration, each CP needs to be put into a large amount of platform to build a platform that provides geographic information services, and constantly maintains geographic information data.
In this case, it is very disadvantageous to the promotion of mobile location information services, which is also not conducive to the development of the value-added business of the mobile Internet. Therefore, the main task on the value chain of SPs throughout the value-added business is to join yourself with a characteristic service, do market promotion, and develop as much end user.
For wireless operators, only one positioning operation platform is far less than enough, it must build the core components - geographic information service platforms in the location information service. Let CP reduces investment, focus on their own services.
The geographic information service platform in the location information service is a key component. From the perspective of wireless operators management and opening location information services, the wireless operators can provide more comprehensive location information services, and also centrally manage and maintain the map database, so that each CP wants to enter the location information service industry. The threshold is greatly reduced, thus promoting the development of location information services.
1 development of geographic information system
Geographic information has been infiltrated into information systems in all walks of life. From the perspective of demand, whether it is a macroeconomic decision support, comprehensive management analysis, or a target of the specific business level, a line of planning, is inseparable from the support of geographic information. From a technical point of view, with the development of computer information technology, especially in the field of mobile computing fields and space database, geographic information technology (GIS) is also integrated into many aspects.
In my country, the construction of geographic information systems is also increasingly valued by the government, especially in some special circumstances, such as "SARS" situations, and tracking people with concern people and moving items, and related to geographic location Analysis and research, it is very important to respond to emergencies on the government.
2 technology development
(1) from GIS to Web-gis. Early geographic information systems have strong professional color, need to introduce complex mathematical models, high requirements for end users, independent design, and open interfaces. Such systems are relatively common in the professional analysis of geological, weather, water conservancy, transportation and other industries. Under this requirement, the application system designed according to the Client / Server mode is much more simple, and the development model is relatively simple and the development cost is low. However, as these C / S modes have been continuously put into use, the disadvantages have gradually exposed. The application system in C / S mode makes only a small amount of professional users can use due to its professionalism, resulting in the existence of a large amount of information. Moreover, the cost of its large-scale deployment and post-maintenance is quite high, which makes the number of users and coverage of the application system have been greatly limited to some extent, which has seriously restrictions on the continued development of the geographic information system. On the other hand, since most systems use an independent design, different systems cannot share data and functions, and the functionally similar problems that have been repeatedly built, resulting in great waste of investment. In recent years, the construction requirements of geographic information systems have been able to meet the needs of more non-professional users. With the gradual popularity of the Internet, the majority of users have become more and more recognized by this universal type of browsers, and the client applications that do not have to be trained will be more and more recognized, so it has laid the foundation of Web-GIS development. In addition, on the technical level, the user requested the geographic information system to open an open design, open the call to other information systems to integrate. Only such a geographic information system is likely to expand from a limited traditional application area while covering more user groups. Browser / Server mode has obvious technical advantages on these issues compared to Client / Server mode. Therefore, in some specific areas, the B / S mode has replaced the C / S mode and has become the preferred development model of the geographic information system.
(2) From the Web-GIS to the network geographic information system. In the 21st century, people are no longer satisfied with the computer table sitting in the office or home, but proposed a higher requirements for "anytime, any-where, anything, anytime, any-where, anything). Strong demand promotes the rapid development of mobile computing field technology, and the client's client is extended from the traditional PC, workstation and other desktop devices to mobile terminals such as PDA, WAP / SMS / KJAVA / BREW mobile phone. Since all mobile terminals first emphasize the feature of easy-to-carry, the hardware design is limited by volume, weight, power consumption, etc., and thus uses an operating system that is completely different from PC and communication protocols different from IP networks. On the other hand, the bottom layer of the geographic information system is developed into a spatial database in combination with database technology. Spatial database technology has great advantages over issues that are more advantages compared to traditional file storage methods in managing massive data, distributed data storage, resolution properties, and spatial data consistency, and thus getting more and more attention.
In recent years, some newly built geographic information systems have gradually introduced these two technologies. These systems require application layers to meet compatibility of various terminal devices, provide good support for heterogeneous or distributed data, and we generally be called all network-based geographic information systems including these types as network geographic information systems.
Since the complexity of the network geographic information system has far exceeded the conventional C / S or B / S architecture, development workload has become more and more large, so you need to find a different from C Multi-layer models of / s or b / s to describe the commonality of these systems. At the same time, the product-level solution is provided on this basis, which provides good underlying support to the application developers to reduce the difficulty of development systems, and improve the quality of the system.
From GIS to WEB-GIS, to the network geographic information system, the application is from the development of all fields from the traditional field, and the user group is from a minority user to a large number of ordinary users, and the technique is technically from the simple architecture to multiple layers. The development of the model.
3 application field
The application field of GIS is very wide, and some typical examples are given below. (1) Digital city. Space information technology with GIS is the core application technology of digital cities. It is integrated with wireless communication, broadband networks, and wireless networks, providing a three-dimensional, multi-level information service system for urban life and business.
Digital city construction includes 4 parts, namely, infrastructure, e-government, e-commerce and public information services. The GIS application runs through the above four parts and all levels, from the urban basic geographic information database to government space data sharing, e-commerce logistics distribution, and network-based public geographic information services, GIS play an indispensable role.
From specific applications, GIS has been widely used in many industries that constitute digital cities, such as urban planning, urban underground pipe network, electricity, telecommunications, public security, fire, first aid. GIS has a wide range of applications in all walks of life, producing a distinctive industry topic GIS, this electrical is the basis for our construction of digital cities. Digital cities can only be based on these topic GIS, sharing, sharing, and expanding.
(2) LBS. With the LBS service, mobile users can easily know their current position, and use terminal query or receive information nearby locations. At the same time, it can be positioned for a particular user or organization, and perform real-time monitoring, tracking, combined with shared electronic map according to the location of the user, to achieve monitoring and scheduling. The LBS business and current TELEMATICS and ITS currently have a very close relationship. Because the space is limited, it will not be described.
(3) Industry application
·oilfield. The application of GIS technology in the oil industry has been previously. In the selection of drilling position, track a pipeline for fault analysis, or to create a new refineries, it is very dependent on geographic understanding to make a sensible business decision. The application of GIS in the oil industry is very wide. According to the application category and the business scope, GIS application can be roughly summarized as petroleum exploration, production development, equipment management, pipe management, transportation management, sales planning, ground construction, and subsidiary facilities. .
·telecommunications. GIS provides the ability of the telecom operator with the ability to integrate maps and other data. By analyzing the spatial location based on the planning and construction of the telecommunications network, the coverage area of mobile signals, market management decision analysis, management current user information, and even find new users, etc. provide the best solutions. The map is displayed through the map will be more intuitive than traditional listing and make decisions more quickly.
·public security. The Construction of Public Security Requires Geographic Information System (GIS) and the support of computer network technology. GIS technology has a lot of application in public security, such as fire command system, security command management system, 110 command management system, household registration system, public security traffic command system, emergency public security command management system, security system, security situation report system, etc. .
· Water conservancy. The application of GIS has expanded to many aspects such as water resources, water environment, soil and water and water, water conservancy projects, and management, have extensive growth points and good growth, and has played a major role in my country's water conservancy construction. .
·traffic. GIS can be applied to highway planning design and management, transportation dispatch, public transport management, railway planning design and management, intelligent transportation system (ITS), etc.
4 GIS system business function in 3G network
Using GIS in a mobile network, the main service that can be provided externally is as follows:
(1) Map Drawing (Mapping)
Map Drawing is the most basic feature provided by the GIS system. The GIS system returns map data according to the client's request (map range, layer, and drawing style, etc.). The map data can be a map in the form of a grid, or a vector data in a particular format. Map gridization defines a variety of picture format output support, such as GIF, JPEG, PNG, WMP,
BMP, etc. The map picture can be returned in the XML document by the Base-64 encoded document, or only the URL can be returned. "Map Drawing" can also "draw" various geometric elements or geographic objects on the "original" map.
Vector maps have a large advantage compared to the grid map. First, the same map, vector format file is about 1/7 of the raster format file, which greatly saves resources used in the wireless network. At the same time, the terminal is highly flexible with the grid map by vector map browser, and the map is larger, the map is magnified, and the reduction, etc. can be completed locally, and there is also an advantage in navigation applications. However, due to the vector map data format, the various manufacturers are not uniform, so if there is multiple GIS systems in the network, they have to consider compatible issues. Due to the limited ability of the terminal, there is no better solution. On the other hand, it is also necessary to post the vector map to the outside of the map. (2) Directory Service (Directory)
It mainly refers to the lookup of POI (points of interest), including the most recently lookup, find and look up according to attributes (such as name, phone number, etc.). The content of the lookup can include shopping malls, hotels, gas stations, etc.
(3) Path Search (route)
Mainly provide a variety of ways (self-driving, bus, walking) driving routes. Path Search Services is a very important service in the LBS business, but also the business that reflects mobile network advantages and features, which is the basis for realizing navigation services.
Path Search Services requires a high requirements for map data, and if you want map data providers to provide complete and accurate road network data, including various rules, such as single line, forbidden left, lanes, and so on. Path Search Service can support the following:
· Full Path: The information is returned to the entire path based on the information specified by the request (self-driving, walking, bus mode, the shortest, the fastest, and the highway, passing through multi-point, etc.).
· The passing through multi-point manner: According to the point sequence requested by the request (the first end point in the absence of the default), search the path through all the specified points.
· Exclusion Conditions: Based on different road types, geographical types, you can designate whether to take a highway, urban area, and you can specify that you don't take it.
· Time and distance information: The service will return multiple starting, endpoints, and segmentation routes, and distance calculation results.
(4) Geocode, encodes a street address or zip code into a geographic location.
(5) Reverse geocode, encodes a geographic location into a street address or zip.
(6) Evaluate the calculation of geometric elements. Currently, the operation supported by the service includes calculating the linear distance between the two points, and the determination point is within a specified area. The calculation service can complete multiple measurement operations through a request.
(7) Navigation. Navigation services can also be seen as one of the path search services, but since the navigation service has its own characteristics, it is independent of the location business specification developed by OGC (Open Gis Consortium). Navigation services can be divided into static navigation and dynamic navigation.
· Static navigation means that the user gets the best path information from the departure and destination before departure. After departure, there is no more prompt information to the user;
· Dynamic navigation is the direction in which the user moves by the GIS system (network side or user) during the traveling process (such as the left turn left, the map is dynamically displayed on the map, and the location of the current user, " The distance between the destination on the driving route, etc.), this service requires higher requirements for the processing power of the system, the accuracy of positioning, the positioning time, and the accuracy of the map.
V. the relevant standardization of LBS business
As mentioned earlier, the LBS business implementation can be divided into two levels, namely location acquisition and information. Accordingly, standardization work also corresponds to different standards.
(1) For the acquisition of the location, the standard of positioning technology is mainly standardized in 3GPP and 3GPP2. The relevant users of the business level certification authorization, business roaming, and privacy management, the standard work, mainly in OMA, but due to the difference between the 3GPP and 3GPP2 in OMA, there is a difference in LBS, the network structure, etc. Standardization progress may slow down. At the same time, it should also be noted that in 3GPP2 is actually the same work as OMA. (2) For the standard work on the level of geographic information, it is currently developed by OGC and has basically completed other services other than navigation services.
In my country, industry standards for Le / L1 interfaces (interface between clients and location servers) have been completed, as well as localization technology industry standards in WCDMA and CDMA2000 systems. The standard related to GIS, currently has a GIS interface, and the enterprise standard of the spaccess interface. The positioning technology standard corresponding to the IP-based level of the OMA will also be launched.
6. The application of LBS business in my country
1 application prospect
The LBS service is a feature business of mobile networks, especially with the use of the 3G system, provides network bandwidth guarantees for LBS applications. Since the LBS businesses have also begun to develop in my country, the factors affecting their development are also very much, and this paper is just a simple analysis of the LBS business that can be encountered.
(1) LBS application of handheld terminal
The LBS application of the handheld terminal is wide, and the voice, SMS, WAP, Java / BREW, and Multimedia SMS / Emails provide various services to public users, including information queries, map services, hand-held terminal navigation, visual trackers, and Regional alarms (such as old people and children), etc.
(2) LBS applications for personal cars
Navigation is the main way of LBS application in the automobile. At present, there is a practical application of car navigation in my country. This application is
GPS Receiver Simplified Edition GIS Engine Map Data Model, this mode has its own limitations, such as high cost (high requirements for car tables, such as processing power, storage capabilities), map resources cannot be shared (If you need to store a large number of map data, you need to store more frequently after the driver), you can't do dynamic map updates, business organization flexibility is limited. These problems can be solved by combining with mobile networks. With the continuous increase in the automotive market, the car navigation business is a business growth point that requires mobile operators. It can provide users with a rich and diverse LBS businesses, such as car anti-theft. Track, help, etc.
The LBS business and the current international TLEMATIC have a very close relationship. The purpose of Telematics is to build a communication platform in the car through the interaction with the network, providing various services for drivers and occupiers. South Korea is relatively active in this regard, and there is currently similar applications, mainly providing car navigation, email services.
(3) Industry application
There are many examples of industry applications, including automobile scheduling (such as taxi scheduling), logistics management, and employee tracking (such as posters tracking), etc., this is no longer described here.
2 Implement the problem of LBS business
The LBS service has a broad application market, but compared to other mobile network-based value-added services, its business implementation involves more and more difficult, so the LBS businesses are truly widely used, and some issues need to be resolved.
(1) Positioning accuracy
At present, the highest precision of the LBS application can use is
GPS positioning technology, but
There is limitations in GPS positioning, such as in depth indoor environments.
GPS positioning. If the network-based positioning is used, the accuracy is greatly reduced, and there is no other better solution. Therefore, more practical practices are to divide the business, classify the requirements of the positioning accuracy. For services with high precision, it is determined by the network side to meet the requirements and performs corresponding processing. Of course, the final solution is to propose a more advanced and geographical environment limited positioning technology, which has begun to study technology in indoors to achieve high-precision positioning. (2) Collection and organization of location information
The LBS finally provides users with location-related content, and location information mainly includes various levels of electronic map and POI information. In terms of electronic maps, all departments in my country have certain levels of data, but these data is not integrated, the map is uniform in various geographics, which is not the operator and map data provider. Unilaterally can do, the country needs to organize organizations, integrating various geographic information resources, and is used for individual industries. For POI information, its rich extent directly affects users' satisfaction with the business, so you need to provide rich POI information. But the workload of information collection is quite large, and it needs to be collected in the ground. Therefore, operators need to integrate POI information provided by various CPs, unified to users, this part of the work requires a uniformity of the operator and various content providers.
(3) Vector Map Browser
Navigation services, especially real-time navigation services, if the real-time download of the map is implemented through the network, then the data is not too big, otherwise the cost of users will be high, which is not conducive to promotion. Vector maps are solutions to this problem, but the vector map is closely related to the format of each GIS manufacturer system content vector data, and it is currently uniform to form in the same format. Therefore, if there is a variety of GIS systems coexisting, the coverage of the business will limit, which can be solved by the terminal to support multiple vector map browsers, but the processing capability and storage capacity of the terminal are high. Therefore, this problem is also worth noting. Figure 2 is a schematic diagram of a vector map operating method.
Figure 2 Vector map service work mode
Seven, conclude
The LBS business has broad development prospects. At present, the current commercial LBS has also reached a considerable degree of penetration. There are many fields involved in the LBS business, and the field of mobile communications is required to be combined with the GIS field. my country is currently attaches great importance to the development of the GIS field, and there is a considerable amount of GIS manufacturers with certain strength and potential. I believe that with the continuous growth in LBS business needs, as well as the continuous development of my country's GIS field, the LBS business will be wider.
