Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/0009—Transmission of position information to remote stations
  • G01S5/0081—Transmission between base stations
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S2205/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S2205/001—Transmission of position information to remote stations
  • G01S2205/006—Transmission of position information to remote stations for emergency situations

Definitions

• the invention relates to a mobile telephone system comprising a number of coverage areas, each coverage area being served by at least one 5 base station, a number of subscriber terminals communicating with one or more base stations, and from which terminals at least some are arranged to determine their geographical location and to inform the base station of the location.
• a typical mobile telephone system covers a wide geographical area and comprises several coverage areas, or cells, each being normally served by one base station.
• a cell size varies greatly, generally according to the volume of call traffic within the area. The cells are generally smaller in high traffic density areas than in regions where fewer calls are set up. Irrespective of the 5 cell size, situations often occur where it is useful to know the geographical location or the direction of travel of a mobile telephone.
• trianguiation in which three or more base stations measure the signal of the terminal, and the location of the terminal is calculated on the basis of the propagation delay of the signals.
• the location of the terminal cannot be detected very accurately on the basis of the trianguiation, and, conse- 5 quently, the location information so obtained cannot therefore be utilized in applications requiring accurate geographical location parameters.
• the direction of travel of a terminal has previously been determined on the basis of successive signal strength measurements made by the base station or the terminal.
• the direction of travel can also be estimated on the basis of the trianguiation. These means cannot fully describe the actual direction of travel and the speed.
• US 5546445 discloses a solution in which a mobile telephone comprises a GPS receiver by means of which the mobile telephone determines its location using a satellite positioning system.
• the lo- 5 cation information is utilized in call invoicing.
• Existing mobile telephone systems have not been able to efficiently utilize the location information in call maintenance.
• An object of the invention is to provide a mobile telephone system so as to solve the above mentioned problems. This is achieved by a mobile telephone system of the type presented in the introduction, which is characterized in that the terminals are arranged to inform the base station of their geographical location at certain intervals, the base station is arranged to store one or more location information items transmitted by each terminal and to determine the direction of travel and the speed of the terminal on the basis of the location information transmitted by the terminal.
• the invention further relates to a mobile telephone system of the type presented in the introduction, which is characterized in that the terminals are arranged to inform the base station of their geographical location at certain intervals, the base station is arranged to store one or more location information items transmitted by each terminal, and when the terminal transmits an emergency call, the base station is arranged to inform an emergency call receiver of the geographical location of the terminal.
• the invention is based on the idea that the location of a mobile telephone can be detected rapidly and accurately by a satellite positioning system, whereby this information can be advantageously applied to various problems to which the application of the location information has previously been impossible.
• the system of the invention provides many advantages.
• the inven- tion enables accurate and fast location determination of a telephone, and the location information can be efficiently utilized in call maintenance.
• the preferred embodiments of the invention are disclosed in the dependent claims.
• Figure 1 shows an example of the mobile telephone system of the invention
• Figure 2 illustrates the operation of the invention when the direction of travel of a terminal is determined and in connection with handover
• Figure 3 illustrates the operation of the invention when a beam forming technique is used
• Figure 4 illustrates the operation of the invention in connection with an emergency call
• Figure 5 illustrates an example of the structure of a terminal of the mobile telephone system according to the invention.
• Figure 1 illustrates part of the mobile telephone system to which the method of the invention can be applied.
• the system comprises a base station 100 having a bi-directional connection 102-104 with subscriber terminals 106- 108.
• the system of the invention can apply any known multiple access method, since the essential features of the invention are independent of the multiple access method used.
• the terminals set up a connection with the base station by using a random access channel. When the connection is set up, the terminal and the base station can transmit signalling information to one another using an associated signalling channel of the connection.
• the terminals are arranged to determine their geographical location and to inform the base station of the location. This is preferably done by means of a satellite positioning system.
• a satellite positioning system is a Global Positioning System GPS.
• the terminals 106, 108 receive a signal 1 10 from a satellite system 112 via several satellite stations and can determine their location by the known methods. Let us first study Figure 2 describing the operation of the invention when the direction of travel of a terminal is determined.
• the terminal 106 receives the signal 110 from the satellite system 112, and uses the signal for determining its location at predetermined, for example regular, intervals.
• the terminal informs the base station 100 of the location at certain intervals. The information can be transmitted on the random access channel or, if the terminal has a call in progress, on the associated signalling channel of the connection.
• the terminals can inform the base station of their geographical location at regular intervals. Alternatively, after determining their location, the terminals compare the new location information with the information last transmitted to the base station. If the new location differs for a pre-set thresh- old from the location reported to the base station, the terminal informs the base station of the geographical location, it is thus possible to reduce signalling traffic between the terminal and the base station.
• the base station 100 receives and stores the location information of the terminal.
• the base station calculates the speed and the direction of travel of the terminal on the basis of two or more pieces of successive location information. Using this information, the base station can eliminate the effect of the Doppler shift from the signal of the terminal.
• the speed of the terminal brings about signal interference, i.e. the Doppler shift. It is known that the Doppler shift can be solved by the formula
• the solution of the invention can also be applied to a base station using a beam forming technique.
• an antenna beam is directed to each communicating terminal.
• the system comprises a base station 100 communicating with subscriber terminals 106-108 in such a way that the base station forms specific antenna beams 300, 302 for each terminal by using the known beam forming techniques.
• the beams can be formed by suitably phasing a signal to be transmitted by means of an antenna array composed of several antenna elements, for example.
• the base station naturally needs information on the direction in which the terminal is located.
• the antenna beam can be directed in the correct direction at each point of time on the basis of the location information transmitted by the terminal.
• the terminals can inform the base station of the location in connection with a call set-up message.
• the base station can thus use antenna beams that are correctly directed in connection with a call set-up acknowledgement, because the location of the terminal is known.
• the solution of the invention is also suitable for use in connection with emergency calls. In that case it is important to rapidly find out the location of the terminal.
• the subscriber terminal 106 determines its location by means of the satellite system 112 and informs the base station 100 of the location at regular inter- vals.
• the base station checks the latest location information transmitted by the terminal and forwards it upward in the network hierarchy to be further delivered to an emergency call receiver 400.
• the solution of the invention can be applied to a number of other targets of application.
• the location and direction information of the terminal can be utilized in connection with handover between base stations when a base station is selected under whose command the terminal should advantageously move.
• the terminal 106 receives the signal 110 from the satellite system 112 and determines its location at predetermined, for example regular, intervals by means of the signal.
• the terminal informs the base station 100 of the location at certain intervals.
• the system also comprises a second base station 200 and a base station control- ler 202 controlling the operation of the base stations and transmitting traffic to other parts of the system and to external systems.
• An entity comprising a base station controller and base stations subject to it is called a base station system.
• the base station controller When the terminal moves towards the second base station the base station controller follows the movement of the terminal and optimally performs the handover.
• the base station system can reserve a channel from a new cell on the basis of the location information of the terminals.
• the terminals maintain a list of the nearby base stations for measurement purposes, for example.
• the base station system can update, using the location information of the terminal, the list of the neighbouring cells that is maintained by the terminals.
• FIG. 5 illustrating an example of the structure of a terminal of the mobile telephone system according to the invention.
• the termi- nal comprises an antenna 500 receiving a signal 502 coming from a base station and a signal 504 coming from a satellite positioning system.
• the signal is applied from the antenna to a filter 506, from where it is applied to radio frequency parts 508, to an analog-to-digital converter 510 and to a decoder 512, and from there further to other parts 524 of the receiver.
• a signal 526 to be transmitted is applied to a coder 518 and further to a modulator 516, and via radio frequency parts 514 and the filter 506 to the antenna 500.
• the ter- minal further comprises a control unit 520 controlling the operation of the parts of the equipment and being typically implemented by a signal processor or a general purpose processor, and in which control unit, the method steps of the invention can be advantageously implemented by software.
• the terminal receives the signal 504 from the satel- lite positioning system with the GPS receiver means 522 by means of which the terminal is able to determine its location by using the known methods.
• the control means 520 direct the terminal to inform the base station of the location via signalling channels at regular intervals. It is to be noted that the figure shows only an example of the structure of a receiver, and the solution of the invention can also be implemented in another type of receiver.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Mobile Radio Communication Systems (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=8549515

Family Applications (1)

Country Status (7)

Families Citing this family (15)

Family Cites Families (8)

• 1997
  • 1997-09-11 FI FI973663A patent/FI973663A/fi unknown
• 1998
  • 1998-09-09 CN CN98809033.3A patent/CN1270744A/zh active Pending
  • 1998-09-09 AU AU91639/98A patent/AU9163998A/en not_active Abandoned
  • 1998-09-09 JP JP2000513435A patent/JP2001517913A/ja active Pending
  • 1998-09-09 EP EP98943912A patent/EP1021930A2/en not_active Withdrawn
  • 1998-09-09 WO PCT/FI1998/000703 patent/WO1999016276A2/en not_active Application Discontinuation
• 2000
  • 2000-03-08 NO NO20001197A patent/NO20001197L/no not_active Application Discontinuation

Non-Patent Citations (1)

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