29-30 June 2007ECAI International Conference – Second Edition Cellid Positioning Method For Virtual Tour Guides Travel Services IONESCU Mircea, STĂNESCU Emil, HALUNGA Simona University Politehnica of Bucharest, National Institute for R&D in Informatics - ICI Bucharest

29-30 June 2007ECAI International Conference – Second Edition Presentation Outlines Information for a Traveler System Architecture Client and Server Applications CelID Positioning Method Editing Points of Interest Testing Observations Conclusions

29-30 June 2007ECAI International Conference – Second Edition Information For a Traveler In our paper is analyzed the possibility of using CellID information for geolocation of a traveler in a city where the area covered by a GSM cell is much smaller. Using that geolocation, the user could get information related to his location. Our technical approach allows a more attractive and interactive way of providing information to a traveler.

29-30 June 2007ECAI International Conference – Second Edition System Architecture Positioning method, allows localization of the user. By reducing the area of localization, the system also reduces the data towards the user, so he can better understand the provided information. A descriptive location is related to natural geographic objects, while spatial locations correspond to a single point in the Euclidean space.

29-30 June 2007ECAI International Conference – Second Edition Detailed View of the System Architecture An API implemented on the client can take responsibility for its own geocoding (deriving a location from a landmark) and reverse geocoding (deriving a landmark from a position) by maintaining a local database of point of interest (POI) data. The client application requires a link to the content provider server.

29-30 June 2007ECAI International Conference – Second Edition Client and Server Applications Client application could use Java ME and JSR-179 API for acquisitioning location data both form the network (CellID, LAC, NMC, NCC) and a GPS receiver. For Symbian phones we have used C++ as a programming language. For provider server implementation are possible two technology combinations for content. The first option is Apache Web Server ( MySql ( PHP( and OpenSSL for secured connection. The second is Apache Tomcat ( Java Model 2 ( MySql and OpenSSL. Content provider server also has the responsibility to integrate, store, edit, share, and display geographically-referenced information. Spatial objects described by spatial data are pure references of real objects on Earths surface and can be represented in numerous ways. Generally, representation is classified into two categories, raster mode and vector mode.

29-30 June 2007ECAI International Conference – Second Edition Layered Maps Maps of service coverage area are highly important for location based systems. For representing maps we could use raster images, vectorial files or satellite pictures. Also, points of interest (POI) need to be considered when speaking about location based services. POI can be added to maps using layers.

29-30 June 2007ECAI International Conference – Second Edition Cell ID Positioning Method Cell term refers to the geographic coverage area of a base station where one or more radio frequencies are present. The size of the coverage area depends on the base station’s signal strength, the degree of attenuation, and on the constitution and intensity of obstacles in the surrounding environment. Each base station is assigned a unique identification number, named CellID. Cell ID has 5 figures for GSM stations and 9 figures for 3G. CellID parameters:  Local Area Code – LAC- The area which includes the cell (31101 for Bucharest area)  Mobile Country Code – 226 for Romania  Mobile Network Code – operator code (01-Vodaphone, 03-Cosmote, 10-Orange)  Geographic Coordinates of the Cell

29-30 June 2007ECAI International Conference – Second Edition Editing Points of Interest

29-30 June 2007ECAI International Conference – Second Edition Adding the position of a Point of Interest

29-30 June 2007ECAI International Conference – Second Edition Points of Interest Associated to a Cell

29-30 June 2007ECAI International Conference – Second Edition Testing Area

29-30 June 2007ECAI International Conference – Second Edition Testing Observations Equipments and software used for testing: The equipment and software applications used for field observations are: Nokia 6600 and LD-3W GPS receiver; Route 66, Nokia NetMonitor, Symbian application for displaying CellID, LAC, and signal strength; Vodafone cellular network operator in Bucharest Romania. Observations of GSM field have showed the following: Signal strength captured with Symbian API is very unreliable because most of the time it was constant. In contrast, NetMonitor application displayed highly variable signal strength between -40dBm and -111dBm; The base station serving the mobile phone was not the one with the highest signal all the time. Serving cells are selected according to a cell allocation algorithm; Vodafone’s Local Area Code has five digits, GSM CellID has five digits and 3G CellID has nine digits; Bucharest is covered by a single 3G Local Area Code (31101). The GSM network is grouped in more than one Local Area.

29-30 June 2007ECAI International Conference – Second Edition Testing Observations (continued) Absolute Radio Frequency Channel Number is between 1 and 62; Minimum required received level for accessing a base station, RxLevelAccessMin: -111dBm; Maximum Phone Location Update period, T321: 40 (1 unit equals 6 minutes, so 40x6=240minutes 240 /60 = 4 hours); Vodafone operates in 900Mhz band but 1800Mhz frequencies could be found. Most of them are Barred, this means those frequencies are reserved for communication purposes only and cannot be used by mobile phones in stand by mode; Sectoring was considered when the network was planned. There are three antennas spread by 120 degrees. The last digit of CellID for 900Mhz band cells may be 1/2/3 and 5/6/7 for 1800Mhz band cells; Observations did not reveal a connection between cell sectoring and azimuth; Lakes reflected the waves, so the signal from one side of the lake traveled to the other side confusing the measurements.

29-30 June 2007ECAI International Conference – Second Edition Conclusions We can conclude that this method is not appropriate for accurate positioning. Although, city guide applications could benefit from minimizing the target’s position. Network operator costs and effort for implementing this solution are reduced. Also, the cost of using this application could be reduced to the fee required by network operators for accessing the GPRS network. We aims at developing the software system depicted in the paper such as to include points of interest for specific locations and to adapt the menu of mobile user to the context and his preferences.