Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Definitions

• the present invention relates to a method, a system and a module for locating a telecommunications terminal.
• the invention finds a particularly advantageous application in the field of mobile telephone services which require knowledge of the location of terminals, such as services linked to emergency and assistance or management of vehicle fleets (road transport, delivery ).
• a first technique is linked to the cellular telecommunication network to which the mobile telephone belongs, GSM / GPRS network for example.
• GSM / GPRS network for example.
• Several location methods based on this network have been standardized (3GPP GSM 03.71, TS 22.071).
• the most commonly used method of this type is that known under the name of "Celljd", that is to say the location by identification of the cell to which the mobile telephone is attached.
• Celljd that is to say the location by identification of the cell to which the mobile telephone is attached.
• Enhanced CelMd is an improvement on the previous one which refines the localization by measuring the travel time back and forth with respect to an antenna of the cell.
• Other methods involve triangulation methods, such as the methods called E-OTD ("Enhanced Observed Time Difference") and TOA (Time Of Arrival). All of these methods by network location have in common the possibility of locating a mobile terminal in standby mode or connected in any area covered by the network, the GSM network in the example presented.
• the location of a terminal can also be obtained using purely geographic location technologies, such as satellite technologies, an example of which is represented by the GPS system ("Global Positioning System ”).
• the GPS system is based on a constellation of 24 satellites, allowing permanent visibility of at least six satellites at any point on the globe.
• the terminals incorporating a GPS receiver are then able to calculate their GPS position by knowing the distances between the receiver and three, or even four or more, satellites of the GPS constellation. These distances are calculated from the measurement of the travel time of signals emitted by the satellites.
• a terminal is known which includes a GSM network location module and a geographic location module with the possibility of reporting the GPS position and network information to a location server.
• the precision provided by these systems is very variable and depends on the size of the network location area in the cell to which the terminal is attached. This size can vary from a radius of a few hundred meters in urban areas to 30 km in rural areas.
• Localization systems based on the GPS system offer increased performance in terms of accuracy, but do not offer the same guarantees in terms of availability and response time, especially in a covered environment. Uncertainty about the location of the GPS varies from 10 to 100 meters in an open environment, therefore generally less than the extent of the GSM location area, with a calculation time of up to several minutes.
• the GPS does not work in a covered environment. This is why it does not meet the requirements of emergency services which can be called up at any time in a wide variety of environments.
• GPSOne location solution has been defined for CDMA networks and is not currently deployed on GSM networks.
• GPSOne is based on equation resolutions involving measurements of GPS signals and the CDMA network to determine the positions.
• the solutions of the equations can be ambiguous when introducing measurements of terrestrial signals and require the elimination of the least probable solutions as well as error detection algorithms. The reliability of this technology therefore strongly depends on the degradations of the signals received. If these signals are subject to many reflections, noises and interference, the error rate may be high.
• GPSOne requires the implementation of on-board solutions in the terminal to obtain optimal performance, which makes this solution complex and inflexible.
• any introduction of new radio technology or a new location technique implies the definition of a new solution by taking into account a new equation.
• the technical problem to be solved by the object of the present invention is to propose a method of locating a telecommunication terminal belonging to a cellular telecommunication network capable of providing a location of said terminal, called network location, to the inside a network location area, the terminal being further equipped with a geographic location system capable of providing a geographic location of said terminal, a method which would make it possible to measure and improve the quality of the location in terms of availability, reliability and accuracy, whatever the environment of the terminal.
• the solution to the technical problem posed consists, according to the present invention, in that said method comprises the following steps: 1) first temporal filtering of the geographic location by comparison of a duration, corresponding to the age of the last geographic location, at a first predetermined maximum duration, - 2) in the event of a negative comparison, selection of the zone defined by said last geographic location,
• the method according to the invention has the effect of evaluating the reliability of the location provided by the geographic location system, GPS system for example, and of retaining this location if it is recognized as reliable. Otherwise, the network location area is used.
• the method further comprises the following steps: - in the case of step 2), spatial filtering of the geographic location by comparison with said network location area, - a) if said geographic location is outside the network location area, estimation of an uncertainty over geographic location, - b) if said geographic location is not outside the network location area, selection of the area defined by said last geographic location, - in the case of step 3), spatial filtering of the geographic location by comparison with said network location area, - a) if said geographic location is outside the network location area, selection of said network location area, - b)) if said geographic location is not outside the network location area, i) second temporal filtering of the geographic location, by comparison of said duration corresponding to the age of the last location geographic ion at a second predetermined maximum duration greater than said first predetermined maximum duration, and comparison of the speed of movement of said terminal with a predetermined maximum speed, ii) in the event of a negative comparison, estimation of an uncertainty in the geographic location, iii ) in the event of a negative
• the comparison is said to be positive if the age of the last geographical location is strictly greater than the first predetermined maximum duration (preamble to step 3) mentioned above), or else, on the one hand, the duration corresponding to the age of the last geographic location is strictly greater than the second predetermined maximum duration, and, on the other hand, if the speed of movement of the terminal is strictly greater than the predetermined maximum speed (step 3) b) iii) supra).
• the comparison is said to be negative if the age of the last geographic location is less than or equal to the first predetermined maximum duration (step 2) mentioned above), or else, on the one hand, the duration corresponding to l age of the last geographic location is less than or equal to the second predetermined maximum duration, and, on the other hand, if the speed of movement of the terminal is less than or equal to the predetermined maximum speed (step 3) b) ii) above ).
• the method according to the invention has the effect of evaluating the reliability of the location provided by the geographic location system, GPS system for example, and of retaining this location if it is recognized as reliable. Otherwise, the network location area or the estimate of the uncertainty on the geographic location are used.
• the reliability criterion here is the age (or seniority of the last geographic location), the consistency between the geographic location and the network location area, as well as the speed of movement of the terminal. In the case where the geographic location is retained, its precision can be refined, as provided for in steps 2) and 3) b) above.
• the estimation of the uncertainty on the geographic location consists in: calculating the distance traveled by said terminal during the period corresponding to the age of the last geographic location, - compare the distance calculated to, on the one hand, the extent of the area defined by the last geographic location, and, on the other hand, the extent of the network location area, - if the distance calculated is included between said areas, establish that the uncertainty of the geographic location is defined by an area whose area is equal to said calculated distance.
• the present invention also relates to a location system of a telecommunication terminal belonging to a cellular telecommunication network, comprising a location server capable of acquiring, on the one hand, a location of the terminal in said cellular network, called network location , inside a network location area, and other hand, a geographic location of the terminal provided by a geographic location system of the terminal.
• a location hybridization module comprising: a temporal filter of the geographic location capable of comparing a duration corresponding to the age of the last geographic location to a first predetermined maximum duration, - a selection module able to select: • the area defined by the last geographic location in the event of a negative comparison, • the location-network area in the event of a positive comparison.
• the location system of a telecommunication terminal is further remarkable in that: - the temporal filter of the geographic location is able to compare a duration corresponding to the age of the last geographic location to a first predetermined maximum duration, and, in the event of a positive comparison, in addition comparing the duration corresponding to the age of the last geographic location to a second predetermined maximum duration greater than the first predetermined maximum duration, - the hybridization module location system further comprises: - a spatial filter which is able to compare the geographic location with the network location area, - a speed filter capable of comparing the speed of movement of the terminal with a predetermined maximum speed, in the case where the duration corresponding to the age of the last geographic location is greater than l at the first predetermined maximum duration, - a module for estimating the uncertainty on the geographic location which is activated either if the geographic location is outside the network location area, in the case where the duration corresponding to the age of the last location is less than or equal to the first predetermined maximum duration, i.e.
• the selection module is able to select: • the zone defined by the last geographic location when the corresponding duration at the age of the last geographic location is less than or equal to the first predetermined maximum duration and the geographic location is not outside the network location area, • the network location area either when the duration corresponding to the age of the last geographic location is greater than the first predetermined maximum duration and that the geographic location is outside the network location area, i.e.
• the module for estimating the uncertainty on the geographic location comprises: - a sub-module for calculating the distance traveled by the terminal during the duration corresponding to the age of last geographic location, - a sub-module to compare the distance calculated with, on the one hand, the extent of the area defined by the last geographic location, and, on the other hand, the extent of the network location area, - an estimation sub-module to establish that the uncertainty on the geographic location is defined by an area whose extent is equal to said calculated distance if the latter is between the above-mentioned areas, La
• La The present invention also relates to a location hybridization module of a telecommunication terminal belonging to a cellular telecommunication network, the cellular network being able to provide r a location of the terminal, called network location, within
• Such a module is remarkable in that it comprises: - a spatial filter which is able to compare the geographic location with the network location area, - a temporal filter of the geographic location suitable for comparing a duration corresponding to the age from the last geographic location to a first predetermined maximum duration, and, in the event of a positive comparison, to further compare the duration corresponding to the age of the last geographic location to a second predetermined maximum duration greater than the first predetermined maximum duration, - a speed filter able to compare the speed of movement of the terminal with a predetermined maximum speed, in the case where the duration corresponding to the age of the last geographic location is greater than the first predetermined maximum duration, - a sub-module estimation of the uncertainty on the geographic location which is activated either if the local geographic location is outside the network location area, in the case where the duration corresponding to the age of the last location is less than the first predetermined maximum duration, i.e.
• a selection sub-module capable of selecting: zone defined by the last geographic location when the duration corresponding to the age of the last geographic location is less than the first predetermined maximum duration and the geographic location is not outside the network location area, • the area of network location either when the duration corresponding to the age of the last geographic location is greater than the first predetermined maximum duration and that the geographic location is outside the network location area, i.e.
• FIG. 1 is a diagram of a particular embodiment of a location system according to the invention.
• Figure 2 is a diagram of a particular embodiment of a location module according to the invention.
• FIG. 3 is a diagram illustrating an example of application of a particular embodiment of a localization system and method in accordance with the invention.
• FIG. 1 shows a location system for a telecommunications terminal 10, for example a mobile telephone belonging to a cellular GSM / GPRS telecommunications network.
• this network is capable of providing a location, called network location, of the terminal 10 inside a network location area.
• Said network location can be defined by the position of the antenna 20, 20 ′ of a cell 21, 21a, 21 'of the network in which the terminal 10 is located.
• the network location zone can be zone 21, 21a, 21 'of antenna coverage in the cell or a smaller area 22, 22a, 22' (crown portion) if the antenna 20, 20 'can locate the terminal 10 more precisely from an exchange of signals, for example by measuring the time of a round trip between antenna 20, 20 'and terminal 10.
• the terminal 10 is equipped with a geographic location system, like the GPS satellite system, capable of providing a geographic location of the terminal 10 with an uncertainty generally less than the extent of the network location area.
• the location system of Figure 1 operates as follows. The user connects 1 his terminal 10 to a service and launches an application 11 which requires very reliable localization of the terminal. Such an application is for example an emergency or assistance service, or even the management of a fleet of vehicles intended for road transport or the delivery of goods.
• the application sends 2 a location request to a mediation platform 12 which in turn sends 3 a request to a location server 13 which includes a GPS and GSM location request.
• the location server 13 interacts 4, 5 with the terminal 10 and the GSM network to calculate, or recover, the GPS position and the GSM position, and returns 6 these positions to the mediation platform 12.
• the mediation platform 12 transmits 7 to a location hybridization module 14 the GPS position, the date of the GPS position, the GSM position, the date of the GSM position and the extent of the GSM location area.
• the localization hybridization module 14 may or may not be an integral part of the mediation platform 12.
• the location hybridization module 14 returns 8 the location that it will have deemed the most reliable following the implementation of the location method which will now be explained with reference to FIG.
• the module 14 receives as input the GPS geographic location of the terminal 10 defined by the set of coordinates Xgps, Ygps, the date Tgps of this location, as well as the instantaneous speed Vgps of the movement of the terminal 10.
• the module 14 also receives the defined GSM network location by the set of coordinates Xgsm, Ygsm, as well as the date Tgsm of this location and the extent Rgsm of the area of network location defining the uncertainty on the network location.
• the module 14 for location hybridization includes a time filter 141 which has the role of calculating the age of the GPS geographic location in order to deduce whether it is relevant and usable.
• - VPmax is the maximum speed of a pedestrian (ex: 5km / h) who would hold terminal 10
• - VCmax is the maximum speed of a vehicle (ex: 50km / h) in which the terminal 10 would be located
• - Amax is the maximum acceleration of a motorized land vehicle in which the terminal 10 would be located
• - tf is the time during which a vehicle which has a speed ⁇ VCmax accelerates and reaches the speed VCmax. tf therefore takes the value (VCmax - Vgps) / Amax.
• the estimation module 144 compares the calculated distance R to, on the one hand, the extent of the area defined by the last geographic location Rgps, and, on the other hand, the extent of the network location area RGSM. If R> Rgsm, the network location area is considered to be the most reliable. If Rgps ⁇ R ⁇ Rgsm, the location is represented by a circle centered on the last geographic location, with a radius having as value the distance R calculated previously. If R ⁇ Rgps, the area defined by the geographic location is considered to be the most reliable.
• the spatial filter 142 of the location hybridization module 14 verifies whether or not the GPS location selected by time filtering is located in the network location area. If the selected GPS location is not located in the network location area, the network location area is recognized by the selection module 143 as reliable and relevant and is retained as the location of the terminal 10. If on the other hand the selected GPS location is located in the network location area, the filter 141 calculates the quantity Tloc-Tgps corresponding to the age of the GPS location and compares it to a second predetermined maximum duration Dmax2, greater than Dmaxl, and being equal to example 3 minutes.
• a speed filter 145 of the location hybridization module 14 compares the instantaneous speed of movement Vgps of the terminal 10 with a maximum speed VPmax equal for example to 5 km / h. If Tloc-Tgps> Dmax2 and Vgps> VPmax, the network location area is recognized by the selection module 143 as reliable and relevant and is used as the location of the terminal 10. Otherwise, the uncertainty estimation module 144 provides an uncertainty associated with the chosen geographic location, as described above.
• the localization hybridization module 14 is a computer device which executes the various steps of the localization process described above, under the command of software instructions. To this end, the location hybridization module 14 includes a hardware storage medium (not shown) comprising these instructions.
• FIG. 3 illustrates an application of the localization system and method which have just been described with reference to FIGS. 1 and 2.
• environment an environment of the discovered type where a GPS localization can be calculated and a covered environment 30, 30 ′ where the absence of a signal does not make it possible to obtain a GPS location.
• terminal 10 passes from an uncovered environment (state 1) to a covered environment (state 2) and remains in this environment (state 3 or 3 ', then state 4). The terminal 10 is then switched off, then switched on later when it is again in a covered environment (state 5). The terminal 10 is located successively in states 1, 2, 3 or 3 ', 4, 5.
• the mobile terminal 10 when it is in operation, is connected to the GSM network. It can therefore be located using GSM information which notably includes the location of the antenna 20, 20 ′ as well as the network location area which can be the extent of the cell 21, 21a, 21 ′ or a extent 22, 22a, 22 'smaller as indicated above.
• the GSM locations relating to states 1, 2 and 4 are identical and are identified by the position M1.
• the GSM location relating to state 5 is identified by the reference M5.
• the GPS position is marked with N1. In the initial discovered environment (state 1), the GPS position will be regularly updated and therefore exact.
• the mobile terminal 10 moves with a pedestrian travel speed ( ⁇ 5 km / h in the example shown) between states 1, 2, 3, 4 and 5, - Terminal 10 travels with a car travel speed (> 5km / h in the example shown) between states 2 and 3 '. Finally, it will also be admitted that a certain time elapses between state 4 and state 5.
• the mobile terminal 10 is initially in an uncovered environment. It is located in a GSM coverage area and can also use a GPS location mode. The method of the invention therefore has for the terminal a position estimated using GSM data (M1) and a GPS position (NT) regularly updated.
• the first check carried out by the process is the age of the GPS position.
• the date and time of acquisition of the GPS position allow the process to estimate the validity of this position.
• the GPS position is recent enough ( ⁇ 60s) to be considered as temporally reliable by the method.
• the method then performs a geographic consistency check between the GPS position (N1) and the GSM position (M1).
• the two positions belong to the same geographic area and are therefore consistent.
• the GPS position (N1) is retained by the method as the most reliable position in this situation and the accuracy of the GPS position can be retained for the location.
• Terminal 10 then enters a building (state 2) and is therefore located when it is located in a covered environment. It cannot therefore acquire a GPS position.
• the localization process then has the GSM position (M1) of the terminal, identical to the GSM position of state 1, and the previously calculated GPS position (N1) in state 1.
• the movement of the terminal 10 from state 1 to state 2 takes place quickly and the time which elapses between the location of the terminal in state 2 and the location of the terminal in state 1 is sufficiently low for the method to consider the GPS position as temporally valid.
• the distance separating state 1 and state 2 from the terminal is also sufficiently small for the GPS position in state 1 to be spatially valid for state 2, that is to say that terminal 10 remains under the cover of the same cell 21 or in the same network location area 22.
• the method therefore considers the GPS position (N1) of state 1 as the most reliable position for state 2. Terminal 10 continues its movement in building 30.
• the terminal 10 is located in state 3, while with the speed of a car, the terminal 10 is located in state 3 '.
• the GPS position returned to the location process always corresponds to the GPS position (N1) in state 1 since, being in a covered environment, it could not acquire a new GPS position.
• the GSM position (M3) differs from the GSM position (M1) of states 1 and 2.
• state 2 we consider that the time which elapses between the location of the terminal in state 3 and the location in state 1 is sufficiently low ( ⁇ 60s) for the method to consider the GPS position (N1) as temporally valid.
• the geographic control of the two positions GSM (M3) and GPS (N1) in this case reveals an inconsistency since the terminal 10 is located under the cover of cell 21a or in another area 22a of network location.
• the method takes into account a new datum which is the instantaneous speed of horizontal movement Vgps of the terminal 10.
• the goal is to make an estimate of the maximum distance D that can be traveled by the terminal 10 during the time which has elapsed between the instant when the GPS position (N1) is recorded and the instant of location in state 3 or 3 ' .
• distance D is an estimate made from realistic assumptions based on the acceleration and maximum speed of a land vehicle classic.
• this calculated distance is then compared with the radius of the GPS accuracy and the radius of the GSM accuracy. If the value of the calculated distance lies between these two comparison values, the method retains the GPS position as the most reliable for the 3 or 3 'state, by defining the area of uncertainty around the GPS position as being a radius having for value this calculated distance.
• the method then considers the GPS position (N1) of state 1 as the most reliable position for state 3 or 3 '. If the value of the calculated distance is strictly greater than the radius of the GSM precision, the method therefore considers the GSM position M3 as the most reliable position for the state 3 or 3 ′.
• the terminal 10 continues its movement again in the building 30 when it is located in the state 4.
• the GPS position reported by the terminal 10 is the position N1 and the GSM data returned shows that the duration D, elapsed between the instant when the last GPS position (N1) is recorded in the terminal 10 and the instant of the location in state 4, is too long for the GPS position (N1) to be considered as sufficient recent.
• the method then performs a geographic consistency check between the GPS position (N1) and the GSM position (M1).
• the two positions belong to the same geographic area and are therefore consistent.
• the location method performs a second check on the date and time of the GPS position (N1), in order to know whether the duration D is short enough for the instantaneous speed of movement Vgps of the terminal 10 and the GPS position are still relevant. Indeed, the longer the duration D, the more the probability of change of speed and position increases. In the example shown, the duration D is compared with a maximum duration of 3 minutes.
• the location method also verifies that said instantaneous speed of movement Vgps of the terminal 10 is not too great.
• the speed Vgps is compared with a maximum speed of 5 km / h (pedestrian speed). If the terminal 10 is moving too fast (speed greater than that of a pedestrian for example), although the duration D is short, the uncertainty remains great regarding the variation in speed and position. Consequently, the second check on the date and time, as well as the check on the speed value are the conditions which can guarantee that the GPS position (N1) remains valid even though the first time check has failed.
• the duration D is less than 3 minutes and the instantaneous speed of movement is comparable to that of a pedestrian.
• the distance traveled during said duration D is then calculated, then, as described above, this calculated distance is then compared with the radius of the GPS precision and the radius of the GSM precision.
• the method retains the GPS position as the most reliable for state 4, by defining the area of uncertainty around the GPS position as being a radius having for value this calculated distance. If the value of the calculated distance is strictly less than the radius of the GPS accuracy, the method therefore considers the GPS position (N1) of state 1 as the most reliable position for state 4. If the value of the distance calculated is strictly greater than the radius of the GSM precision, the method therefore considers the GSM position M1 as the most reliable position for state 4. The terminal 10 is then switched off for part of its journey from state 4 to state 5, then restarted inside building 30 '. It is located in state 5. The GPS position supplied to the location process is the position N1 acquired when the terminal was in an uncovered environment in state 1.
• the returned GSM position M5 is up to date and corresponds to the network location area 22 'of the cell 21' in which the terminal is located (state 5).
• the time filtering performed on the GPS position rejects the GPS position because it is too old. Spatial filtering also fails because the GPS (N1) and GSM (M5) positions are not located in the same geographic area. The method therefore retains the GSM position of state 5 as the most reliable position and indicates the corresponding uncertainty.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Position Fixing By Use Of Radio Waves (AREA)

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• 2005
  • 2005-04-14 EP EP05757251A patent/EP1751576A1/de not_active Withdrawn
  • 2005-04-14 WO PCT/FR2005/000899 patent/WO2005103754A1/fr active Application Filing
  • 2005-04-14 US US11/578,655 patent/US20080171557A1/en not_active Abandoned

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