(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2008/0139219 A1
`(43) Pub. Date:
`Jun. 12, 2008
`Boeiro et al.
`
`US 2008O139219A1
`
`(54) HYBRID LOCATING METHOD AND SYSTEM
`FOR LOCATING AMOBILE TERMINAL INA
`WIRELESS COMMUNICATIONS NETWORK
`
`(75) Inventors:
`
`Gianluca Boeiro, Torino (IT):
`Davide Bertinetti, Torino (IT):
`Eugenio Rondina, Torino (IT):
`Davide Cavallo, Torino (IT)
`Correspondence Address:
`FINNEGAN, HENDERSON, FARABOW, GAR
`RETT & DUNNER
`LLP
`901 NEW YORKAVENUE, NW
`WASHINGTON, DC 20001-4413
`(73) Assignee:
`Telecom Italia S.p.A., Torino (IT)
`(21) Appl. No.:
`11/794,169
`
`(22) PCT Filed:
`(86). PCT No.:
`S371 (c)(1),
`(2), (4) Date:
`
`Dec. 27, 2004
`
`PCT/EPO4/53710
`
`Jan. 17, 2008
`
`Publication Classification
`
`(51) Int. Cl.
`H04O 7/20
`
`(2006.01)
`
`(52) U.S. Cl. ..................................................... 45S/456.2
`
`ABSTRACT
`(57)
`Method of hybrid location in a wireless system includes a
`terminal having both a satellite receiving section and a cellu
`lar receiving section operating according to at least a first and
`a second locating mode; a locating center having a position
`calculation module and a wireless communication channel
`between said terminal and said locating center. The server
`performs the steps of receiving a locating request; analyzing
`available resources and locating requirements associated
`with the locating request; selecting at least one locating mode
`according to the locating requirements and the available
`resources; setting instructions including locating measures to
`be acquired and response triggering conditions; sending the
`instructions to the terminal through the wireless communica
`tion channel; receiving acquired locating measures from the
`terminal; and calculating a position information from the
`locating measures.
`
`
`
`
`
`
`
`
`
`SATELLITE
`REFERENCE
`RECEIVERS
`NETWORK
`
`
`
`SERVICE
`PROVIDER
`
`Page 1 of 11
`
`SAMSUNG EX-1064
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`

`

`Patent Application Publication
`
`Jun. 12, 2008 Sheet 1 of 2
`
`US 2008/O139219 A1
`
`
`
`
`
`
`
`
`
`SATELLITE
`REFERENCE
`RECEIVERS
`NETWORK
`
`SERVICE
`PROVIDER
`
`
`
`CONTROL UNIT
`
`l".
`
`Page 2 of 11
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`

`

`Patent Application Publication
`
`Jun. 12, 2008 Sheet 2 of 2
`
`US 2008/01392.19 A1
`
`RECEIVING
`LOCATION RECQUEST
`
`50
`
`AcauRING REQUIREMENTs Lu
`
`ANALYSING REQUIREMENTS L-60
`
`65a
`
`
`
`
`
`DETERMINING
`ASSISTANCE DATA
`
`DETERMINING
`ALGORTHM
`
`DETERMINING
`COMMANDS/INSTRUCTIONS
`
`SENDING DATA
`
`RECEIVING DATA
`
`EVALUATIO-risp
`
`
`
`NO
`
`AWAITED
`MEASURES
`
`
`
`85
`
`COMPUTING
`POSITION
`
`COMPUTING
`POSITION
`
`
`
`O
`
`
`
`GENERATING
`POSITION MESSAGE
`+ACCURACY
`
`GENERATING
`POSITION MESSAGE
`ACCURACY
`
`SENDING
`
`Fig. 3
`
`
`
`FURTHER
`TERATION ?
`
`110
`
`GENERATING
`FAILURE
`MESSAGE
`
`120
`
`115
`
`Page 3 of 11
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`

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`US 2008/O 1392.19 A1
`
`Jun. 12, 2008
`
`HYBRD LOCATING METHOD AND SYSTEM
`FOR LOCATING AMOBILE TERMINAL INA
`WRELESS COMMUNICATIONS NETWORK
`
`TECHNICAL FIELD OF THE INVENTION
`0001. The present invention relates to the field of wireless
`communications systems, and more particularly to a method
`and system for locating a mobile terminal according to dif
`ferent modes.
`
`BACKGROUND ART
`0002 Hybrid location methods are known to exploit dif
`ferent localization techniques, such as satellite measures (us
`ing e.g. the GPS-Global Positioning System—navigation
`system) and cellular measures (e.g. based on the measure of
`the electromagnetic field). These known methods use suitable
`algorithms that, based upon two or more pluralities of mea
`Sures acquired by the terminal, are intended to globally
`improve the performance of the positioning, in terms of accu
`racy, availability, and so on.
`0003. The estimation of the position of the mobile termi
`nal is carried out either at the terminal itself or at a network
`server, also called mobile location center (MLC). In the latter
`case, the MLC receives the measures from the mobile termi
`nal and, if necessary, uses additional data such as a network
`database (including data about the physical environment
`around the mobile terminal) and/or data received from refer
`ence GPS receivers.
`0004 U.S. Pat. No. 6.249,245 discloses a system combin
`ing GPS and cellular technology, wherein the mobile terminal
`calculates its position using GPS data and information sent by
`a cellular network. Information can include differential GPS
`error correction data. When the requisite number of GPS
`satellites are not in view of the GPS receiver, the system
`utilizes a GPS pseudosatellite signal that is generated by one
`or more base stations of the cellular network independent of
`the GPS. When the requisite number of GPS satellites is
`temporarily not in view, position is calculated using the cel
`lular network infrastructure. In the alternative, cellular sig
`nals already transmitted from a base station are used to cal
`culate a round trip delay and then a distance between the base
`station and the terminal, which replaces a missing GPS sat
`ellite signal.
`0005 WO 01/86315 discloses a system, wherein a mobile
`unit compiles a set of positioning databased on the signals
`received from GPS satellites and from a cellular communi
`cation network. The positioning data are then transferred to a
`calculation center where the most precise location calculation
`possible is performed.
`0006. Applicant has noted that these known systems have
`the inherent shortcoming of assuming that the cellular and/or
`satellite measures are available to the base station.
`0007. Other GPS solutions provide for an “assisted GPS,
`wherein the network server sends suitable data for improving
`the receiver performances.
`0008 For example, U.S. Pat. No. 6,389,291 discloses a
`GPS system that can operate in different modes, including a
`standalone mode, wherein a mobile communications device
`computes its position; an autonomous mode, where the
`mobile communications device transmits the computed posi
`tion to another component of the communications network; a
`network aided mode, wherein the network aids the mobile
`communications device; and a network based mode. In this
`
`system, the selective switching of the GPS receiver is per
`formed either automatically or manually at the wireless com
`munications device in either local or remote control.
`0009. Applicant has noted that this system has the inherent
`shortcoming that it does not take into account the terminal
`resources which thus cannot be efficiently managed. For
`example, this system may decide to use an autonomous or
`standalone mode (i.e. where the mobile device computes its
`position) and thus decide to wait until a position calculation
`has been done; but this choice could be not optimal when the
`battery level is too low (and thus does not enable data to be
`acquired within the provided acquisition time). Furthermore,
`the choice at the terminal's end does not take into account the
`calculation power existing at the server. In fact, Applicant has
`observed that the performances of a GPS/AGS (Assisted Glo
`bal Positioning System) mainly do not depend upon the
`operation mode (i.e. with or without assistance data transmis
`sion), but they mainly depend upon the local conditions of the
`mobile terminal and are generally unpredictable.
`0010. In general, the only choice of the operation mode is
`not sufficient to have an efficient localization procedure and
`does not ensure the optimal trade-off between requirement
`compliance and resource management. For example, for pre
`set accuracy requirements, it may be not efficient to wait for
`the terminal to calculate the position, when the network
`server has a suitable algorithm able to process a Subset of
`measures that can be acquired in a shorter time.
`0011 US 2002/0019698 describes a solution wherein a
`positioning method selecting device automatically deter
`mines the best possible positioning method available for use
`by the terminal's applications, based on requirements speci
`fying the quality of service.
`(0012 US 2003/0045303 describes a system wherein the
`terminal receives assistant information from a positioning
`server and measures signals based onto the received informa
`tion; in case the positioning information collected is suffi
`cient, it displays the location computed by the positioning
`server; otherwise it displays a corresponding message.
`(0013 EP-A-1 418 439 discloses a portable telephone
`aimed at reducing power consumption and shortening posi
`tioning time, by selecting a method for determining the loca
`tion according to the distance from an objective point or a
`reception level of a downlink signal. The telephone automati
`cally Switches a positioning method according to the distance
`between its location and the objective point. In detail, the
`portable telephone receives the location of the base station
`when in a distant place from the objective point, regards it as
`the location of the telephone and exerts control to gradually
`increase the number of times the GPS positioning is selected
`as it come closer to the objecting point.
`0014 US-A-2003/014.4042 discloses a method wherein
`the rate at which position information is transmitted may be
`adjusted based upon the battery strength and/or whether the
`mobile station is operating in the emergency mode. The
`mobile station determines whether the battery is low and
`transmits this information to the network. The mobile station
`may also transmit whether it is currently operating in an
`emergency mode. Based on this information, the network
`may adjust the rate.
`
`OBJECT AND SUMMARY OF THE INVENTION
`0015 The aim of the present invention is therefore to
`provide a method and a system that are able to take in due
`account the conditions and resources both on the terminal and
`
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`US 2008/O 1392.19 A1
`
`Jun. 12, 2008
`
`on the server side, so as to manage in an efficient way the
`different variables affecting the performance of the localiza
`tion process.
`0016 Advantageously, these variables include the battery
`charge of the mobile terminal, type and requirements of the
`service; available resources; calculation power at the server,
`and so on.
`0017. The present invention efficiently allows picking up
`measures from the terminal, in accordance with the service
`requirements or the available resources.
`0018. According to the present invention, there are pro
`vided a method and a system of hybrid location as defined in
`claims 1 and, respectively, 15.
`0019. The present system uses a hybrid location method
`and is based on the observation that in a hybrid location
`method, it is advantageous that the position detection is car
`ried out at the network server. In fact, the network server
`knows its own processing and calculation potential and the
`service requirements and, moreover it can know the available
`resources, since:
`0020 it receives the localization request from a user
`(e.g., an external service provider oran LCS-LoCal Ser
`vice client which may be the terminal) together with
`various requirements; and
`0021 the server knows the requirements and the poten
`tial of the available location algorithm; generally the
`results and the performance depend upon the used algo
`rithm and the available measures and data. Therefore,
`the server is able to determine which data should be sent
`to the terminal and which data and measures (satellite,
`cellular) should be gathered from the terminal to satisfy
`the service requirements; and
`0022 the server can know the available resources both
`at the network side (e.g. bandwidth) and/or at the termi
`nal side (e.g. battery charge level). Resources of the
`terminal can be in fact communicated to the server on
`request (or periodically).
`0023. In one embodiment, the server decides which mea
`sures/data should be acquired from the terminal; i.e. the
`server decides the trade-off between cellular and satellite
`measures/data. In this way, the server may acquire only the
`data that are necessary to satisfy the accuracy requirements;
`thereby the localization procedure may be optimized as
`regards e.g. the time needed by the terminal to send the
`acquired measures, the number of transmitted bytes, or ter
`minal battery consumption.
`0024. In another embodiment, the server controls the navi
`gation module integrated in or connected to the mobile ter
`minal based on events that cause Switching on and off and/or
`based on the on and off times of the GPS module. In this way,
`the navigation management logics can be decided and
`adjusted not only based on the service requirements but also
`taking into account the available algorithm capability, which
`in general is variable with time.
`0025 Preferably, the navigation management logic takes
`into account also the terminal resources.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`0026. For a better understanding of the present invention,
`a preferred exemplary non-limitative embodiment will now
`be described with reference to the attached drawings,
`wherein:
`
`0027 FIG. 1 shows a block diagram of a communications
`network according to an embodiment of the present inven
`tion;
`0028 FIG. 2 shows a block diagram of a mobile terminal
`of the communication network according to FIG. 1;
`0029 FIG. 3 shows a flow-chart of an embodiment of the
`present localizing method.
`
`DETAILED DESCRIPTION OF A PREFERRED
`EMBODIMENT OF THE INVENTION
`0030 FIG. 1 shows the block diagram of a communication
`system 1 using a hybrid location method. The communication
`system 1 comprises a plurality of wireless devices or termi
`nals 2, e.g. cellular handphones, each having at least some of
`the functions typical of a satellite positioning (e.g., GPS)
`receiver/processor (as explained in greater detail hereinbe
`low). The terminals 2 are spread randomly in an area inside
`which the position of the single terminal 2 is to be determined.
`The communication network 1 further comprises a server 3
`(mobile localization center MLC); a wireless communica
`tions network 4, for example a GSM network, including a
`plurality of base stations 7 (e.g. BTS or Base Transceiver
`Stations, in a GMS network) and arranged between the ter
`minals 2 and the server 3. The network is adopted to receive
`signals emitted by a plurality of satellites 5.
`0031 Preferably, a MLC 3 is connected to a satellite ref
`erence receiver (e.g., a GPS receiver) or a network of refer
`ence receivers 8. The presence of one or more reference
`receivers is preferred especially in case of transmission of
`assistance data. Furthermore, in the final phase of the location
`process when the server collects the measures from the ter
`minal (as explained below more in detail), it can be advanta
`geous that the server can infer the position of the satellites
`(e.g. through the ephemerides parameters) at the times when
`measures were taken. Although, it is envisaged that the server
`can request the terminal to provide the satellite positions, it
`can be more efficient that the server takes this information
`from the satellite receiver(s) which it is connected to.
`0032 Each terminal 2 (FIG. 2) comprises an RF module
`10 (e.g. operating according to the GSM, the GPRS General
`Packet Radio System—or the UMTS Universal Mobile
`Telecommunications System—standard), a navigation or
`NAV module 11 (e.g. operating according to the GPS, the
`AGPS or the GALILEO standard), a control unit 13, con
`nected to the RF module 10 and to the NAV module 11; a SIM
`(Subscriber Identity Module) 14, connected to the control
`unit 13; and a battery 15, connected to all the other units of the
`terminal 2.
`0033. The NAV module 11 is of standard type and com
`prises a satellite receiver (e.g. a GPS receiver) that is kept on
`only when measures are to be acquired, as below discussed.
`The terminal may include other modules to enable other
`functions of the wireless network, Such as voice, video or data
`communication.
`0034. The control unit 13, the implementation whereof
`may be of a known type and thus not described in detail, e.g.
`including a client software developed in Symbian OS or in
`other manner, has the function of controlling the activities of
`the terminal 2, based on programs stored in the control unit 13
`itself. In particular, the control unit 13 controls the RF module
`10 so as to periodically measure the electromagnetic field (RF
`measures) within a preset number of frequency channels, in a
`per se known manner. The measures are carried out on the
`signals received from the base stations 7; the control unit 13
`
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`US 2008/O 1392.19 A1
`
`Jun. 12, 2008
`
`also chooses, among the performed measures, a maximum
`number of RF measures, for example up to 7 measures for a
`network 4 of the GSM type, corresponding to the channels the
`identification code whereof can be decoded by the control
`unit 13. Furthermore, the control unit 13 controls the NAV
`module 11 so as to perform GPS measures from the signals
`received from the satellites 5, in a perse known manner. The
`control unit 13 is also able to receive instructions and data
`from the server 3 (through the network 4) and to send the
`server 3 the RF (e.g. GSM) and the NAV (e.g. GPS) measures,
`e.g. in the form of Sms (Short MeSsages) or as data in an
`IP-GPRS connection.
`0035. The SIM 14 stores, in a perse known way, the user's
`data, including the user's identification number (IMSI In
`ternational Mobile Subscriber Identity—), the services pro
`vided, by contract, by its provider, and further utilities.
`0036. In an alternative embodiment, the SIM 14 stores the
`programs necessary to control the RF and the NAV modules
`10, 11 and to acquire the measures needed to locate the
`terminal 12.
`0037. The network 4 allows the communications between
`the terminals 2 and service centers, systems and apparata
`connected to the network 4, including the MLC 3.
`0038. The MLC 3 is a server comprising a central process
`ing unit 20 and a storage unit 21 including a first area 21a
`storing reference databases and a second area 21b storing
`Software modules or programs necessary to determine the
`position of the terminals 2 and to transmit the determined
`position to the requester (generally a service provider 22
`connected to the server 3, or to the terminal 2).
`0039. In a preferred embodiment, the MLC3 is connected
`to a network 8 of satellite reference receivers that allows a
`continuous update of the satellite information of the data
`bases stored in the first area 21a.
`0040. The central processing unit 20 is intended to process
`the programs stored in the second area 21b of the storage unit
`21 and to calculate the position of the terminals 2 using the
`data sent by the terminals 2 and the reference databases stored
`in the first area 21a of the storage unit 21.
`0041. The reference databases stored in the first area 21a
`of the storage unit 21 preferably comprise:
`0042 territory databases including the data of the build
`ings with a resolution of e.g., 10 m;
`0043 configuration databases including the configura
`tion for the cellular network, such as the position of the
`base stations 7, the parameters of the irradiation dia
`grams, etc.;
`0044) satellite databases including data of the satellite
`orbits and all other data necessary for the correct opera
`tion of the locating algorithm.
`0045. The above databases are updated continuously, to
`allow a correct locating procedure. Satellite databases are
`updated using information collected continuously from the
`reference receivers network 8.
`0046. The data exchange between the terminals 2 and the
`server 3 are essentially of three types:
`0047 assistance messages/data: they are sent by the
`server 3 to the terminal 2 in order to improve the perfor
`mances of the NAV module 11 as regards time needed by
`the terminal to send the acquired measures and to
`improve the sensitivity in the signal acquisition;
`0048 instruction/configuration messages/data: they are
`sent by the server 3 to the terminal 2 in order to config
`
`ure/instruct the terminal as regards the management of
`the RF and NAV modules 10 and 11:
`0049 cellular/satellite measures: they are sent by the
`terminal 2 to the server 3 in order to allow calculation of
`the position of the terminal 2.
`0050. In the following description of an embodiment of
`the present invention, the following definitions apply:
`0051. Observation time t. This is the on-time of the
`NAV module 11, during which the NAV module 11
`acquires the satellite signal(s). After the expiry of the
`observation time, the NAV module 11 can be switched
`off (e.g., disconnected from the battery 15);
`0.052
`Locating time: time period set by an entity requir
`ing location (e.g., a service provider or the terminal), in
`order to calculate the position of the terminal. An
`example of locating time can be the time within which a
`service provider wants to receive a location, e.g., 1 min.
`In this non-limitative example, the locating time can be
`seen as a service requirement;
`0.053
`Response time: time specified by the server or
`calculated by the terminal 2 based upon instructions
`from the server 3, the expiry whereof causes the terminal
`to send the acquired measures to the server,
`0.054
`Applicability time: time delay during which old
`data are still usable.
`0055. Before describing the hybrid location method car
`ried out by the communications system 1 of FIG. 1, the
`following aspects are highlighted.
`0056 AS regards the satellite positioning system (e.g.,
`GPS):
`0057 a satellite positioning receiver generally needs a
`certain time for acquiring the signal and acquiring the
`measures;
`0.058
`the battery consumption in a satellite positioning
`receiver is relatively high (which is a critical aspect in
`telephone handsets):
`0059 during the acquisition, the measure occurs in a
`progressive way based on the received signals (typically,
`a first time Atl is needed to obtain a first measure; a
`second time At2 is needed to obtain a second measure,
`and so on).
`0060. As regards a hybrid cellular/satellite locating solu
`tion:
`0061 different sets of hybrid cellular/satellite measures
`are performed, based on the available algorithm and the
`accuracy requirements.
`0062. In general the system 1 is able to perform one or
`more of the following measures:
`0.063 N1 GPS measures of the pseudorange type:
`(0.064 N2 GPS measures of the Doppler type:
`0065 Nn satellite measures according to any other
`known satellite method;
`(0.066 M1 cellular measures of relative OTD (Observed
`Time Difference) time;
`0067 M2 cellular power measures:
`0068 M3 cellular measures of the absolute time, for
`example of RTT (Round Trip Time);
`0069 Mm cellular measures according to any other
`known cellular method.
`0070. As regards definition and explanation of the above
`measures, reference is made (as regards the GPS measures) to
`E. D. Kaplan, “Understanding GPS: principles and applica
`tions’. Artech House, London, 1996, Chapter 5, Section 5.1.
`6, pp. 172-193 and (as regards the cellular measures) to 3GPP
`
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`
`TS 25.215 “Physical layer Measurements (FDD). Differ
`ent combinations of the above measures, as regards quantity
`and/or type, originate different accuracy performances as a
`function of the localization algorithm available at the server 3.
`0071. The acquisition of some of the above measures (gen
`erally, the satellite measures) may be carried out in a non
`negligible time, resulting in a delay in the response and an
`increase in the power consumption.
`0072 Therefore, according to an aspect of the invention,
`when time and/or consumption may be critical, the server 3
`may instruct the terminal 2 to perform and collect a subset of
`measures, or, according to an alternative aspect of the inven
`tion, the server 3 may instruct the terminal 2 not to perform
`complete measures, but to pick up one or more satellite/
`cellular “snapshots”. In particular, the server 3 may fix a
`maximum duration of the Snapshot (e.g., a few ms), which
`allows a reduction of the response time and shifts the problem
`of determining the measures in the server 3. The server is in
`factable to process the “snapshots’ in combination with other
`available data to obtain the required measures.
`0073. Therefore, in the following description, the term
`“measure' indicates both standard measures and 'snap
`shots’.
`0074 Considering the above, the present system provides
`for a flexible management of the different aspects related to
`the operation of the cellular/satellite modules of the terminal
`and the location method.
`0075. In particular, according to one embodiment of the
`invention, the server 3 sends the following data and instruc
`tions to the terminal 2:
`0076 observation time t.
`0077 type and number of cellular measures (M1, ...,
`Mn) and satellite measures (N1,..., Nn) to be acquired;
`0078 frequency of acquisition of the measures;
`0079 conditions triggering the data transmission;
`0080 management of old data, stored at the terminal.
`0081. Hereinbelow, the above data and instructions are
`discussed in detail.
`0082. Observation Time
`is set by the server 3 based
`0083. The observation time t
`on the service requirements and/or as a function of the battery
`level (as explained in detail hereinbelow). In fact, the exact
`time needed by the NAV module 11 for acquiring the mea
`sures is unpredictable. To overcome this difficulty, the server
`3 may set a maximum acquisition time, i.e., the observation
`time, which depends on the service requesting the terminal
`location and on the charge level of the terminal battery 15.
`Examples of the observation time t
`are:
`I0084
`small t
`for services sensible to the delay (e.g.,
`information services wherein the latency—delay
`between the location request and response—is overrid
`ing with respect to accuracy);
`I0085 medium t for services less sensible to the delay
`but requiring a certain accuracy (e.g. m-commerce/toll
`ing services, home-Zone billing, etc., where the location
`position influences money or billing transactions; in
`Such cases, the services sets some constrains on accu
`racy and latency);
`for services requiring maxi
`0086 long/very long t
`mum accuracy (e.g. for emergency or security services,
`for example upon an emergency call due to road acci
`dent, when the call should be localized with the utmost
`accuracy even if the location requires along observation
`time);
`
`depending on the battery charge and calcu
`0087 t
`lated by the terminal 2, based upon a function of the
`present battery charge the parameters whereofare set by
`the server 3. Thereby, a trade-offbetween the acquisition
`time and the consumption is obtained. An exemplary
`function may be the following:
`
`wherein A and B are parameters set by the server 3 and sent to
`the terminal 2 (e.g. depending on the requesting service or
`fixed values) and batt level is the present battery charge (for
`example, the percentage value).
`I0088 For a service requiring a medium tradeoff between
`accuracy, latency and battery charge, for example
`0089 A=0s
`0090 B=60s
`which, for a battery charge of 50%, gives an observation time
`t
`30s.
`0091. Thereby, the observation time is calculated dynami
`cally, as a function of the terminal conditions.
`0092. According to an alternative implementation, the bat
`tery charge level information is communicated to the server 3,
`for example, on request (or periodically), and thus the calcu
`lation of the t
`value (as a function of the battery charge
`level) is made by the server itself prior to sending the relative
`instructions to the terminal 2.
`(0093. Type and Number of Cellular/Satellite Measures
`0094. The server 3 sets the type and number of measures to
`be acquired by the terminal 2 and to be sent to the server
`according to the requesting service and/or any detected con
`ditions, in any manner known per se.
`0.095
`Frequency of Acquisition of the Measures
`0096. The required frequency is a function of the service
`requesting location (for example, services requiring tracking
`of the terminal need higher frequency) and/or the requested
`accuracy (when more sets of measures are available, the loca
`tion of the terminal 2 may be calculated with higher precision)
`and/or the available bandwidth (a higher report frequency
`requires a higher bandwidth).
`0097 Triggering of Data Transmission
`0098. The server 3 may specify different conditions trig
`gering the transmission of the measures from the terminal 2,
`hereafter referred to as triggering conditions. For example,
`the server 3 may require transmission of data after a preset
`response time t; or after occurrence of a response event
`es: at a certain response frequency f. after acquiring a
`preset number of measures it; etc. The server 3 may set one or
`more triggering conditions, that cause transmission of the
`measures each time one of the triggering condition is satis
`fied. In case of multiple conditions, multiple transmission
`occurs. The triggering conditions are set based on the type of
`requesting service, to obtain a trade-off among the require
`ments of latency, accuracy, bandwidth (number of bits).
`0099 Examples of triggering conditions based on the
`response time set by the server 3 are:
`I0100
`t,
`t, when the server 3 requires the maximum
`number of measures during the observation time (e.g. as
`required by services for which accuracy is a critical
`condition);
`I0101
`t
`t 1<t (e.g. response time equal to a preset
`percentage of the observation time or equal to a preset
`value lower than the observation time; for example, this
`condition is used when the server 3 carries out a first, row
`location based on first measures available to the terminal
`
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`Jun. 12, 2008
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`or on previously saved measures, before reachingt. In
`this case, except when a multiple even is set (see below),
`the measures acquired between tlandt are not sent to
`the server 3 but stored at the terminal 2 and are thus
`available if the server 3 requires a new measure opera
`tion;
`t2>t; this condition causes transmission
`I0102 t
`of the measures acquired during the observation time
`after switching-off of the NAV module 11. This condi
`tion is typically used when the server 3 wants to reduce
`the battery consumption; for example the NAV module
`11 is switched on for a short observation time, a response
`is sent to the server 3, in case after performing some
`processing at the terminal 2. Such as acquiring a number
`of cellular measures, performing calculations, and so on.
`0103 Examples of triggering conditions based on events
`a.
`
`e1; this condition triggers the transmission of
`I0104 e,
`the response when an event e1, specified by the server 3,
`occurs; examples of events include acquisition of a certain
`number of satellite measures. This condition is particularly
`Suitable as a trade-off between the requirements of accuracy,
`latency and number of bits:
`I0105 ee,
`(e1, e2, t1, t2,...); this condition triggers
`the transmission of the response each time the events e1
`and e2 occur and times t1 and t2 have lapsed. In general,
`the server may set a vector including a plurality of events
`and/or a plurality of response times. This allows to
`obtain the utmost accuracy, taking into account the cir
`cumstances. As an example, e1 causes transmission
`when the measures related to a first satellite are avail
`able; e2 when the measures related to two first satellites
`are available; transmission occurs also at times t1, t2,
`and so on. The satellite measures may be updated and
`transmitted together with the cellular measures.
`0106 Management of Old Data
`0107 The terminal stores at least some of the data previ
`ously acquired, together with the respective acquisition date
`(old data time t). For example, old data may include the
`last set of MGPS measures, with Me4; the last set of KGPS
`measures, with KZ4; the last set of cellular measures. There
`fore, according to another aspect of the invention, the server
`instructs the terminal about the conditions that cause trans
`mission of the old data. To this end, the server specifies an
`applicability time t, of the stored data and the conditions
`triggering the transmission of the old data before or after
`expiry of the applicability time (e.g. number of acquired
`measures). For example, the server may specify the transmis
`sion of old data when the number of available measures is
`lower than that required and when the old data time is lower
`that the applicability time (trost).
`0108. When the old data are sent by the terminal 2, the
`server 3 may use or not these data, according to the service
`requirements. I