Location-Based Information Push as a Short Message Service
            – Its Architecture, Design, and Applications
      ...
instant information conveniently. Because the mobile stations are often moving from a
base station to another, it is a sub...
BTS units and hence multiple cells. The BSC reserves radio frequencies, manages the
handoff of a mobile station from one B...
We can know that signals are conveyed through each base station. This study is based
on mobile subscribers of GSM system, ...
We adopt the standard of GSM 03.71 which is the digital cellular telecommunications
system (phase 2+); Location Services (...
Table 1. The characteristic analysis of mobile positioning technique
Technology          Cell-ID          TOA/TDOA        ...
user and the user's location to receive a short message. SMS first appeared in GSM in
about 1991. Although with the advent...
Start



                                               Select area




                                            Search...
Systematic platform             Short message sender            Mobile subscribers




                                   ...
area, so we can know which mobile subscribers are in the base stations of given area.
According to Cell-IDs of the base st...
Conference on Distributed Computing Systems Workshop.
Jonathan P. Munson, Vineet K. Gupta, Location-based notification as ...
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Location-Based Information Push as a Short Message Service

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Location-Based Information Push as a Short Message Service

  1. 1. Location-Based Information Push as a Short Message Service – Its Architecture, Design, and Applications Jang-Ruey Tzeng1 Patrick S. Chen2 Wei-Hsuan Tsao3 Center for Strategies and Industrial Study(CSIS) Dept. of Information Management, Tatung University , No.40,Sec.3,Zhongshan N.Rd., Taipei City 10433,Taiwan ROC petertzeng@gmail.com1 chenps@ttu.edu.tw2 mimo0722@hotmail.com3 ABSTRACT “Push” and “Pull” are two main kinds of information propagation. Nowadays, mobile communication environment, cellular phones are not only prevalence, but also become an important means for acquiring information. Due to the limited viewing windows and small bandwidth, most information presented to cellular phones is in the form of short message. In the present time, information broadcasting to newly entering mobile stations is technically feasible. But, mobile stations used to move from one BTS to another, making the location of a mobile station a difficult task. If we want to push information to specified mobile subscribers in a given area, we need to remodel the system, since it is a waste for the sender to send a message out of the given area, and it is also a disturbance for the receiver to receive an unwanted message. In order to determine whether a mobile station is in a given area, we have to search the entire location table, causing a huge system cost. Therefore, by way of using Cell-ID location technique that we suggest to construct and maintain a LBS database, registering all currently connected mobile stations in a specified area. The proposed system cannot only be used in commercial area such as for local retailers to send information to their customers, but also in public sectors such as for police to send warnings in emergent rescue. Keyword: Short Message Service, Information Push, Location-Based Service, Cell-ID 1 Introduction In the recent years we have seen increased attention being given to Location-Based Service (LBS) in the mobile commerce application. LBS is a service in which only people in certain area will be given the information, but not out of the area. Perfect use of LBS could bring more convenience to people‟s daily life. “Push” and “pull” are two main kinds of information propagation. In pull ser vice, customer takes the initiative to submit requests to the server, and the server responds with information requested. It is a common way for people getting information from the website. With push service, the sender sends information to the client according to certain rules. For example, it can be the broadcast of radio or the sending of advertising letter. In the present-day mobile communication environment, cellular phones are widely used, becoming an important means for acquiring information, so people often receive messages passively. Because mobile communication is characterized by its narrow bandwidth and cellular phone is limited by its viewing window, short message service is still regarded as the most widely used value-added application. Short message service is easy to handle; its cost is low; it is one of the most welcome services in mobile commerce. It is a common practice to push information to mobile stations, so we can acquire 1
  2. 2. instant information conveniently. Because the mobile stations are often moving from a base station to another, it is a subject worthy of study how to push information to specified mobile stations in a given area. Let us think over a scenario: a bakery would like to sell out all its bread before it closes in two hours. So, we send promotion information as a short message to notify the consumers near the bakery. Because some customers may leave this area, it will be a waste to send a message out of this area. So we have to improve the existing GSM technology, because mobile stations may stay in this area, they may leave this area too. It is a waste for the sender to send a message out of the given area, and it is also a disturbance for the receiver to receive an unwanted message. How to facilitate an adequate information push is the topic of this discussion, in which we do not intend to modify the current system of GSM, but to adopt the mechanism of GSM LCS to set up a notification system. 2 Literature Review 2.1 GSM Architecture GSM was originally developed to provide a second-generation communication technology for Europe so that the same subscriber units could communicate throughout the continent. GSM first appeared in 1990 in Europe. It contains the essential “intelligent” functions for the support of personal mobility, especially with regard to user identification and authentication, and for the localization and administration of mobile users. (Stallings, 2005) Figure 1.GSM Architecture In Figure 1, GSM system is divided mainly into Mobile station, Base station subsystem (BSS) and Network Subsystem (NS). Mobile stations (MS) are pieces of equipments which are used by mobile service subscribers for access to services. These consist of two components, one is Mobile Equipment (ME) and another one is Subscriber Identity Module (SIM). A base Station Subsystem (BSS) consists of a base station controller (BSC) and one or more base transceiver stations (BTS). Each BTS defines a single cell and it also includes a radio transceiver, a radio antenna and a link to a base station controller. A BSC may be collocated with a BTS or control many 2
  3. 3. BTS units and hence multiple cells. The BSC reserves radio frequencies, manages the handoff of a mobile station from one BTS to another. The network subsystem (NS) provides a link between the cellular network and the public switched telecommunications networks (PSTN). The NS controls handoffs between cells in different BSS, authenticates users and validates their accounts, and includes functions for enabling worldwide roaming of mobile users. The central element of the NS is the mobile switching center (MSC). It has four databases: (1) Home Location Register (HLR) database: The HLR stores information, both permanent and temporary, about each of the subscribers that „belongs‟ to it. It stores IMSI, MSISDN, MSRN, Subscriber information, LMSI etc. Figure 2. Figure 2.Mobile subscriber data in the HLR (2) Visitor Location Register (VLR) database: One important, temporary piece of information is the location of the subscriber, and this location is determined by the VLR into which the subscriber is entered. The visitor location register maintains information about subscribers that are currently physically in the area covered by the switching center. It also stores some information, which is IMSI, MSRN, TMSI, LAI, MSISDN, etc. Figure 3.Mobile subscriber data in the VLR (3) Authentication Center (AuC) database: The database is used for authentication activities of the system. (4) Equipment Identity Register (EIR) database: The EIR plays a role in security which keeps track of the type of equipment that exists at the mobile station. 3
  4. 4. We can know that signals are conveyed through each base station. This study is based on mobile subscribers of GSM system, because base stations were densely set up with high coverage in Taiwan. 2.2 Location-Based Notification There are many kinds of location-based services available, among them is the notification system: 1. The ability to precisely locate subscribers according several positioning techniques. 2. Precisely defined and arbitrarily located notification areas. 3. The ability to detect entrance to a notification area within a short time period, such as one minute or less. 4. The ability to track each and every wireless subscriber at an interval that will satisfy requirement. Notification Subscribers Initiator Location Determination Proximity Notification Detection Areas Preferences Filter Notification Client Composition Specifications Notification Delivery Figure 4.High-level model of location-based notification In Figure 4, “subscribers” are the set of subscribers to whom notifications may be sent. The Notification Initiator begins the process by sending a subscriber ID to the Position Determination function, which computes the position of the given subscriber using the wireless carrier‟s position-determining technology. “Notification Area” is the set of geographic areas that have been created by clients of the location-based notification service. Proximity Detection determines whether a subscriber is in a notification area. The Preferences Filter blocks notifications from being sent to subscribers when their preferences indicate they do not want notifications from a particular client. Notification Composition composes a notification to be sent to a subscriber, based on what the client specified, and the Notification Delivery system actually delivers the notification. For example, this may be the carrier‟s SMS system. 4
  5. 5. We adopt the standard of GSM 03.71 which is the digital cellular telecommunications system (phase 2+); Location Services (LCS); Functional Description; Stage2.” It is mainly a standard for GSM in LCS (Figure 5). It shows the logical architecture defined by GSM for its LCS (Location Services) network feature. The LCS Client sends a LCS Service Request to the Gateway Mobile Location Center (GMLC), supplying the subscriber‟s IMSI (International Mobile Subscriber Identifier) or MSISDN (Mobile Station ISDN Number) to obtain the position of a mobile subscriber. The GMLC needs to know which MSC is currently serving the subscriber, and so obtains this information from the Home Location Register (HLR). The request is then forwarded to the appropriate MSC. The MSC forwards the request to the Serving MLC, either directly or through the BSS (Base Station Subsystem), depending on how the SMLC is connected. (Jonathan et al., 2002) MS HLR Lh RRLP Le Lg Ls Lb LCS Gateway MSC/ Serving BSS Client MLC VLR MLC Figure 5.Logical Architecture for GSM Location Services There are two points of the GSM LCS architecture that we should mention: one is designed to serve location requests for individual subscribers, and another is designed around the requirement that applications have no prior knowledge of a subscriber‟s location, but know only subscriber‟s IMSI or MSISDN. We fallowed this architecture in GSM LCS. 2.3 Cell-ID positioning technique There are various kinds of action-oriented technology available, three of them are utilized extensively at present. The first one is network-based positioning technique. It utilizes the signal send out by mobile subscribers, determines their locations in the base station or the network system server that publishes the position of the mobile subscribers, such as Cell-ID and TOA/TDOA. The second one is terminal-based positioning technique which utilizes signals sent out by base station to a mobile subscriber, and the mobile station calculates its position relative to the mobile station, such as E-OTD/OTDOA. The third is a hybrid-based technique. The location is determined by the mobile station and mobile network together (Table 1). . 5
  6. 6. Table 1. The characteristic analysis of mobile positioning technique Technology Cell-ID TOA/TDOA E-OTD/OTDOA A-GPS Positioning Network- Network- terminal- hybrid- based based based based based Proximity 200~2000m 50~200 m 50~150m 5~50m positioning Start the machine Positioning slowly time 1~3 seconds 3~6 seconds 5~8 seconds 10~40 seconds Start the machine fast 1~30 seconds End The software GPS machine; GPS network、GPS demand of fine tuning Connected time RNC、LMU equipment receiver、IP- the office synchronism Based network Demand of none none Location software, GPS receive module, end user Logical processing location software Network GSM/GPRS GSM/GPRS E-OTD-GSM/GPRS GSM/GPRS system WCDMA WCDMA OTDOA-WCDMA WCDMA CDMA2000 CDMA2000 CDMA2000 Suitable Location service Location service, Location service, Location service, services Tracking service Tracking service Tracking service Data resource: MIC of Institute for Information Industry, 2006/08 Cell-ID is the basic reference for mobile positioning techniques; COO (Cell of Origin) positioning technique is also based on Cell-ID. Cell of Origin (COO) is a mobile positioning technique for finding a caller's cell (the basic geographical coverage unit of a cellular telephone system) location. It may be used by emergency services or commercial use. COO is the only positioning technique that is widely used in wireless networks and is used for Phase one of 911 service in the US. It considers the location of the base station to be the location of the caller. This is not very accurate, but may be useful in rural locations and in the cities. In the Figure 6 we show the COO positioning method. Figure 6.Cell-ID positioning method of network-based 2.4 Short Message Service Short Message Service (SMS) is a mobile data service that allows alphanumeric messaging between mobile phones and other equipment such as voice mail systems and email. SMS is a store-and-forward system. Messages are sent to a Short Message Service Center (SMSC) from various devices such as another mobile phone or via email. The SMSC interacts with the mobile network to determine the availability of a 6
  7. 7. user and the user's location to receive a short message. SMS first appeared in GSM in about 1991. Although with the advent of 3G, SMS is still based on the existing GSM architecture. In this study, we adopt the short message service to deliver message to mobile subscribers in a given area. We utilize Cell-ID positioning technique to implement the system. 3 System Analysis and Design We propose an architecture for this system in this chapter. 3.1 System Analysis According to the literature cited above, the study sets up a structure based on GSM LCS. Following this structure, we compose the format of short message and Cell-ID positioning technique, to establish real time location-based information push service. The basic design of the system is: (1) Select an area, in which we want to push information. (2) Search mobile subscribers according to client‟s request. (3) Register the state when a mobile subscriber enters this area, and deliver the data back to MSC/VLR database. (4) Register the state when a mobile subscriber leaves this area, and update MSC/VLR database. Figure 7 shows a general idea of systematic maintenance. Figure 7. Systematic maintenance A mobile subscriber will register to the mobile station when it enters this base station, and the data will be stored in VLR database. So, we only need to know the Cell-ID of each base station in a given area when we search. We also know the cellular number of mobile subscribers in this given area. We have to protect the privacy of the subscribers. 3.2 Procedure of system When requested by the client to push information, the system will look up the database in a given base station. Based on Cell-ID, the each base station will search all mobile subscribers in its area. It will get a list of mobile subscribers that are of the interest of the client. Success or failure in sending will also be recorded for future billing. Figure 8 shows the system flow. 7
  8. 8. Start Select area Search MS of the database Acquire subscribers of MS in given area Save failure data No Yes Save success Deliver in log file data in log file End Figure 8.Flow chart for System 4 Implementation of the Location-Based Information Push System 4.1 System architecture For mobile subscribers often move from one area to another. This will be registered automatically. The data will be stored in VLR database, VLR will forward the data to HLR to update the position information. Simultaneously, it can obtain the subscriber's basic data from HLR, and then store back to VLR database. Architecture of the system is decomposed into System platform, Short Message Sender and Mobile Subscribers. System Platform contains a LBS database and system interface, and there is an interface to the short message sender. Figure 9 shows architecture for the system. 8
  9. 9. Systematic platform Short message sender Mobile subscribers ............. LBS Database Query Short System Message Deliver Interface Platform Figure 9.Architecture of System The main concept of the system is to obtain subscribers‟ cellular numbers from LBS to deliver when we want to push short message to specified mobile subscribers. Mobile subscribers who are not in this area will not receive any message, so the senders who are unwilling to waste the expenses on delivering short message. 4.2 System interface Figure 10 shows the three parts of the system interface that are the windows for delivering short messages, selecting area and LBS database query. Delivering short messages Selecting area LBS Database query windows Figure 10. System main components The window for LBS database query is used to select mobile subscribers in given area. We first query the wanted area and then select one or more base stations in this given 9
  10. 10. area, so we can know which mobile subscribers are in the base stations of given area. According to Cell-IDs of the base stations, so we can select the mobile subscribers‟ cellular phone numbers we want. Finally, the window for delivering short message is an interface to input message and to click to deliver. The mobile subscribers will receive a message we pushed. This system has many applications, not only in commercial area such as for local retailers to send information to their customers, but also in public sectors such as for police to send warnings in emergent rescue. Figure 11 shows a case for the mobile subscribers in given area to receive a message of earth fall. Figure 11. A message of warning emergent earth fall 5 Conclusion Nowadays, short message services are widely used, but many of them are not targeted, causing a waste of money. The mechanism introduced in this research is effective in solving this problem. Many applications are conceivable, for example, retailer transmits instant news to specific customers, investment firms publish real-time stock market tendency, etc. In public sectors, government departments take precautions against natural calamities, or police agencies evacuate people in flooded area. In the future, we will put the system into connection with telecommunication industry. We would like to see how well it works in real environment. We will test the overall efficiency of system and investigate the time needed for sending a short message online. Whether the message sent to the customers is well-accepted is also worthy of studying. REFERENCES Cell-loc Location Technologies. <http://www.cell-loc.com/how_tech.html> GSM 03.71: “Digital cellular telecommunications system (Phase 2+); Location Services (LCS); Functional Description; Stage 2”. Ivana Podnar, Manfred Hau Content to Mobile Users, The 22nd International 10
  11. 11. Conference on Distributed Computing Systems Workshop. Jonathan P. Munson, Vineet K. Gupta, Location-based notification as a general-purpose service, International Workshop on Mobile Commerce archive Proceedings of the 2nd international workshop on Mobile commerce, pp.40-44 William Stallings,Wireless Communications& Networks, Pearson Prentice Hall Emiliano Trevisani, Andrea Vitaletti, Cell-ID location technique, limits and benefits: an experimental study. Eberspaecher, Joerg,「GSM switching, services, and protocols」,Wiley,2001. 11

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