18-03-2011, 11:45 AM
Presented by:
K.KARTHIK
[attachment=10474]
ABSTRACT
Mobile positioning technology has become an important area of research, for emergency as well as for commercial services. Mobile positioning in cellular networks will provide several services such as, locating stolen mobiles, emergency calls, different billing tariffs depending on where the call is originated, and methods to predict the user movement inside a region. The evolution to location-dependent services and applications in wireless systems continues to require the development of more accurate and reliable mobile positioning technologies. The major challenge to accurate location estimation is in creating techniques that yield acceptable performance when the direct path from the transmitter to the receiver is intermittently blocked. This is the Non-Line-Of-Sight (NLOS) problem, and it is known to be a major source of error since it systematically causes mobile to appear farther away from the base station (BS) than it actually is, thereby increasing the positioning error.
In this paper, we present a simple method for mobile telephone tracking and positioning with high accuracy. Through this we will discuss some technology used for mobile positioning and tracking
In a cellular mobile telecommunication network, the whole service area is divided into a several coverage areas having respective base stations (BS). Each BS coverage area is called a "cell." Each BS is provided with a frequency of a range between 450 to900 MHz. More than one cells can use same frequency. Only condition is that no two adjacent cells must have same frequencies. An MTSO controls these BSs so that a subscriber can continue his call without interruption while moving between different cells. The MTSO can reduce the time required for calling a subscriber by locating the cell of the subscriber. In case of an emergency like a fire, or a patient needing first aid treatment, the mobile subscriber should be accurately located. Tracking the location of a mobile subscriber within the boundary of a cell in a mobile telecommunication network is known as "location based services
Mobile technology includes mainly two functions. They are call fixing and hands-off process. All the BSs are sending a signal of power 25 to 30w to the mobile unit. When a user switches ON his mobile, it will search for the strongest signal and got connected to that BS. Then the mobile unit sends an identification signal to the BS. When he fixes a call, the BS accepts the request and sends the request to the BSC and MTSO. Then the MTSO will searches where the subscriber is and connects the call.
When a user moves to another cell the MTSO will change the frequency allotted to it and allots the frequency of the new BS.For both these processes GEOLOCATION of the mobile unit is essential.
2. NEED FOR GEOLOCATION
One of the most powerful ways to personalize mobile services is based on location. The location based services, provides the subscribers very best of the service. Recent demands from new applications require positioning capabilities of mobile telephones or other devices. The ability to obtain the geo-location of the Mobile Telephone (MT) in the cellular system allows the network operators to facilitate new services to the mobile users. The most immediate motivation for the cellular system to provide MT position is enhanced in accident emergency services. The geolocation of the mobile user could provide services like
• Emergency service for subscriber safety.
• Location sensitive billing.
• Cellular Fraud detection.
• Intelligent transport system services.
• Efficient and effective network performance and management.
2.1 ARCHITECTURE OF A GEOLOCATION SYSTEM
An example of geolocation system architecture [KOS00] is shown in Figure. As we said earlier, in order to fix a call the subscriber we are calling must be located accurately. A geolocation service provider provides location information and location aware services to subscribers.
Upon a request from a subscriber for location information about an MS, the service provider will contact a location control center querying it for the coordinates of the MS. This subscriber could be a commercial subscriber desiring to track a mobile device or a PSAP trying to answer an E-911 call. The location control center will gather information required to compute the MS’s location. This information could be parameters such as received signal strength, BTS ID, TOA of signals, and so on that we discuss later. Depending on past information about the MS, a set of BS’s could be used to page the MS, and directly or indirectly obtain the location parameters. These are sometimes called Geolocation base stations (GBSs). Once this information is collected, the location control center can determine the location of the mobile with certain accuracy and convey this information to the service provider. The service provider will then use this information to visually display the MS’s location to the subscriber. Sometimes the subscriber could be the MS itself, in which case the messaging and architecture will be simplified, especially if the application involves self-positioning
3. TECHNOLOGIES USED FOR GEOLOCATION
3.1 HANDSET BASED MOBILE POSITIONING AND TRACKING
3.1.1. GLOBAL POSITIONING SYSTEM (GPS)
A mobile telephone can be located by a mobile telephone itself or through a mobile telecommunication network. To locate the mobile telephone by itself, the mobile telephone is provided with a GPS receiver to calculate its location in latitude and longitude coordinates based on the location information received from a satellite through the GPS receiver.
• Increases the price and the size of the mobile telephone.
• The load on the mobile telephone is increased.
• Power consumption is high.
3.2 DIRECTION BASED GEOLOCATION
3.2.1 ANGLE OF ARRIVAL METHOD
As said earlier there will be transmission and reception of signals between the mobile unit and BSs. This method calculates the angle of arrival of signal receiving at the BS. When a mobile user switches the system ON it receives the signal from different base stations, may be 3 or 4 or more. The angle of arrival method two or more base station for the determination. It measures the direction of signal falling on the base station and measures the angle of incidence with respect to a normal and determines the position of the system. Angle of arrival method is not an accurate method used for the mobile positioning because of its some disadvantages such as:
• The determination of the system will be in error if the angle of incidence is changed due to any obstacle like atmospheric particles or due to scattering etc.
• The accurate location cannot be determined if the mobile user is in between the BSs, that is in a straight line.
It cannot be used for the indoor environments.
K.KARTHIK
[attachment=10474]
ABSTRACT
Mobile positioning technology has become an important area of research, for emergency as well as for commercial services. Mobile positioning in cellular networks will provide several services such as, locating stolen mobiles, emergency calls, different billing tariffs depending on where the call is originated, and methods to predict the user movement inside a region. The evolution to location-dependent services and applications in wireless systems continues to require the development of more accurate and reliable mobile positioning technologies. The major challenge to accurate location estimation is in creating techniques that yield acceptable performance when the direct path from the transmitter to the receiver is intermittently blocked. This is the Non-Line-Of-Sight (NLOS) problem, and it is known to be a major source of error since it systematically causes mobile to appear farther away from the base station (BS) than it actually is, thereby increasing the positioning error.
In this paper, we present a simple method for mobile telephone tracking and positioning with high accuracy. Through this we will discuss some technology used for mobile positioning and tracking
In a cellular mobile telecommunication network, the whole service area is divided into a several coverage areas having respective base stations (BS). Each BS coverage area is called a "cell." Each BS is provided with a frequency of a range between 450 to900 MHz. More than one cells can use same frequency. Only condition is that no two adjacent cells must have same frequencies. An MTSO controls these BSs so that a subscriber can continue his call without interruption while moving between different cells. The MTSO can reduce the time required for calling a subscriber by locating the cell of the subscriber. In case of an emergency like a fire, or a patient needing first aid treatment, the mobile subscriber should be accurately located. Tracking the location of a mobile subscriber within the boundary of a cell in a mobile telecommunication network is known as "location based services
Mobile technology includes mainly two functions. They are call fixing and hands-off process. All the BSs are sending a signal of power 25 to 30w to the mobile unit. When a user switches ON his mobile, it will search for the strongest signal and got connected to that BS. Then the mobile unit sends an identification signal to the BS. When he fixes a call, the BS accepts the request and sends the request to the BSC and MTSO. Then the MTSO will searches where the subscriber is and connects the call.
When a user moves to another cell the MTSO will change the frequency allotted to it and allots the frequency of the new BS.For both these processes GEOLOCATION of the mobile unit is essential.
2. NEED FOR GEOLOCATION
One of the most powerful ways to personalize mobile services is based on location. The location based services, provides the subscribers very best of the service. Recent demands from new applications require positioning capabilities of mobile telephones or other devices. The ability to obtain the geo-location of the Mobile Telephone (MT) in the cellular system allows the network operators to facilitate new services to the mobile users. The most immediate motivation for the cellular system to provide MT position is enhanced in accident emergency services. The geolocation of the mobile user could provide services like
• Emergency service for subscriber safety.
• Location sensitive billing.
• Cellular Fraud detection.
• Intelligent transport system services.
• Efficient and effective network performance and management.
2.1 ARCHITECTURE OF A GEOLOCATION SYSTEM
An example of geolocation system architecture [KOS00] is shown in Figure. As we said earlier, in order to fix a call the subscriber we are calling must be located accurately. A geolocation service provider provides location information and location aware services to subscribers.
Upon a request from a subscriber for location information about an MS, the service provider will contact a location control center querying it for the coordinates of the MS. This subscriber could be a commercial subscriber desiring to track a mobile device or a PSAP trying to answer an E-911 call. The location control center will gather information required to compute the MS’s location. This information could be parameters such as received signal strength, BTS ID, TOA of signals, and so on that we discuss later. Depending on past information about the MS, a set of BS’s could be used to page the MS, and directly or indirectly obtain the location parameters. These are sometimes called Geolocation base stations (GBSs). Once this information is collected, the location control center can determine the location of the mobile with certain accuracy and convey this information to the service provider. The service provider will then use this information to visually display the MS’s location to the subscriber. Sometimes the subscriber could be the MS itself, in which case the messaging and architecture will be simplified, especially if the application involves self-positioning
3. TECHNOLOGIES USED FOR GEOLOCATION
3.1 HANDSET BASED MOBILE POSITIONING AND TRACKING
3.1.1. GLOBAL POSITIONING SYSTEM (GPS)
A mobile telephone can be located by a mobile telephone itself or through a mobile telecommunication network. To locate the mobile telephone by itself, the mobile telephone is provided with a GPS receiver to calculate its location in latitude and longitude coordinates based on the location information received from a satellite through the GPS receiver.
• Increases the price and the size of the mobile telephone.
• The load on the mobile telephone is increased.
• Power consumption is high.
3.2 DIRECTION BASED GEOLOCATION
3.2.1 ANGLE OF ARRIVAL METHOD
As said earlier there will be transmission and reception of signals between the mobile unit and BSs. This method calculates the angle of arrival of signal receiving at the BS. When a mobile user switches the system ON it receives the signal from different base stations, may be 3 or 4 or more. The angle of arrival method two or more base station for the determination. It measures the direction of signal falling on the base station and measures the angle of incidence with respect to a normal and determines the position of the system. Angle of arrival method is not an accurate method used for the mobile positioning because of its some disadvantages such as:
• The determination of the system will be in error if the angle of incidence is changed due to any obstacle like atmospheric particles or due to scattering etc.
• The accurate location cannot be determined if the mobile user is in between the BSs, that is in a straight line.
It cannot be used for the indoor environments.
