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
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/87—Combinations of radar systems, e.g. primary radar and secondary radar
  • G01S13/878—Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector
• • 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
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/003—Bistatic radar systems; Multistatic radar systems
• • 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
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
  • G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
• • 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
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/06—Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements

Definitions

• the present invention relates to methods and systems for localization. It is particularly, but not exclusively, concerned with localization techniques based on TDoA for wireless devices. Background of the Invention
• Position location systems provide the most critical tracking support information required for location-sensitive services and applications. These may include commercial, enterprise and consumer location-based services and applications such as: delivery vehicle location tracking, package or shipment location tracking; service personnel location management; workforce management; asset management; roadside assistance, city/area boundary maintenance, and driving directions; enhanced dispatch; public safety services including the provision of emergency services (112 and 911) caller location information to emergency service centers; security applications including tracking the locations of probationers; child location tracking; parents may want to be able to track the whereabouts of their children; service locator; and location in wireless sensor networks.
• commercial, enterprise and consumer location-based services and applications such as: delivery vehicle location tracking, package or shipment location tracking; service personnel location management; workforce management; asset management; roadside assistance, city/area boundary maintenance, and driving directions; enhanced dispatch; public safety services including the provision of emergency services (112 and 911) caller location information to emergency service centers; security applications including tracking the locations of probationers; child location tracking; parents may want to be able to track the whereabouts of their children; service locator; and
• location-based services have great potential for commercial applications that complement mobile device usage.
• the ability to provide services and information that are relevant to the users at their specific location could significantly enhance direction finding, the location of specific services such as cash points and restaurants, or even checking on the whereabouts of family members and friends.
• the new field of Location-Based Computing also depends heavily on information provided by position location systems.
• Two ellipses in arbitrary orientation and distinct location can be in one of the following six placement configurations as shown in Figure 9 with respect to each other: ⁇ they are separated and non-overlapping one completely encloses the other they share only one common point they share only two common points
• the embodiments of the present invention are interested mainly in the application of ellipse intersection. Therefore, reference is made to existing literature [2] on how to determine the placement configurations described above and also the points of intersection.
• the semi-major axis, semi-minor axis, and eccentricity of an ellipse are determined given the location of its foci and a point on the ellipse. Without loss of generality, these parameters of a standard ellipse (as shown in Figure 14) can be determined as follows.
• ⁇ e distance ( f x , f 2 ) /(2 a )
• the parameters of the ellipse can also be determined if the value of D shown in Figure 14 is known.
• the value of D can be defined as the difference between the path indirectly from p to f 2 through p and the path directly from f l to f 2 .
• An object of the present invention is to provide a method and system for locating a client device connected to a wireless network.
• aspects of the present invention provide for methods and systems able to physically locate a client device broadcasting in a network, by utilizing some of the inherent properties of ellipses.
• a first aspect of the present invention provides a system configured to physically locate a client device, the system including: a transmitter station configured to transmit a first wireless signal; at least 3 receiver stations; and a location management station; wherein: each receiver station is configured to receive the first signal and a second wireless signal transmitted from the client device and triggered by receipt of the first signal by the client device; the receiver stations and/or the location management station are configured to determine a time difference of arrival between the first signal and second signal for each of the receiver stations; and the location management stations is configured to: compute, based on the corresponding time difference of arrival for each receiver station, a plurality of ellipses each associated with a respective receiver station, each ellipse having a first focal point corresponding to the transmitter station and having a second focal point corresponding to the respective receiver station; determine a plurality of intersection points between pairs of said ellipses; and estimate the location of the client device using said determined intersection points.
• the system of this aspect implements an ellipse-based position location scheme which can allow for efficient location discovery of clients in wireless networks.
• the scheme can use the time difference of arrival (TDOA) between two signals at a plurality of receivers, which are respectively directly received from the transmitter and rebroadcast from the client. By measuring the TDOA of these signals locally at each receiver, geometric relations can be formulated and used in determining the location of the client.
• TDOA time difference of arrival
• the system can also operate with no communication overhead for the transmitter, client and signal receivers.
• a semi-major axis or a semi-minor axis of each ellipse may be calculated based on the corresponding time difference of arrival for that receiver station.
• the receiver stations and/or the location management station may be configured to determine a distance, delta(receiveri), which is the distance corresponding to the time difference between the receipt of the first signal and receipt of the second signal at the i th receiver station. This distance can then be used in the computation of an ellipse having the i th receiver station as one of its focal points. This distance can be calculated from the time difference of arrival.
• the location management station may be configured to calculate, for an i th ellipse
• a semi-major axis a t which is half of the sum of: a) a known distance, distance (f lr f 2 ), between the respective receiver station and the transmitter station; and b) delta(receiver i ' ).
• the location management station may be configured to calculate, for an i th ellipse
• the location management station may be configured to calculate, for an i th ellipse
• the location management station may be configured to solve, for at least two distinct pairs of the computed ellipses, the following simultaneous equations:
• ⁇ h t ,k t is the center of the ellipse corresponding to an i th receiver station and is computed based on the foci of the said ellipse receiver station and the transmitter locations;
• ( h j , k j ) is the center of the ellipse corresponding to an j th receiver station and is computed based on the foci of the said ellipse receiver station and the transmitter locations; and each (x, y) satisfying the above simultaneous equations corresponds to the coordinates of an intersection point between the pair of ellipses i.e. the ellipses corresponding to the i th and j th receiver station.
• the computation overhead at the receiver stations and the location management station can be kept very low, as the location detection involves only simple algebraic operations over scalar values.
• the location management station may determine an intersection point in common between the at least two pairs of computed ellipses.
• the receiver stations may share a common clock.
• the receiver stations may each include an independently running clock, and the clocks of each receiver station may share a nominal frequency.
• the location system of this aspect does not require time (i.e. time-of-day) synchronization between the signal receivers, only the coarse frequency synchronization, typically of the order of tens of parts-per-million (ppm).
• the system can even work for the case where the signal receivers are run asynchronously. In such cases it is preferable that the frequency accuracies of the signal receivers are in the order of not more than, say, 50ppm.
• the transmitter station and the receiver stations may all be transceiver stations, and the transmitter station may be chosen from the transceiver stations by determining a smallest round trip delay from each transceiver station to the client.
• the first signal and the second signal may be periodic signals which share the same nominal frequency.
• Each receiver station may include a signal phase detector circuit, the circuit may count at a frequency f os a number of counts Q between receiving the first signal and receiving the second signal at the respective receiver station, and the distance
• the system may include the client device, and the client may be configured to transmit the second signal, the transmission of the second signal being triggered by receipt of the first signal at the client.
• the location management station may be part of either the transmitter station or one of the receiver stations, or the client device, or separately provided.
• a second aspect of the present invention provides a method of locating a client device using a wireless network, having the steps of: transmitting, from a transmitter station, a first signal; receiving, at a client device, the first signal; transmitting, from the client device, a second signal which corresponds to the first signal and whose transmission is triggered by receipt of the first signal; receiving, at each of at least three receiver stations, the first signal and the second signal; determining, for each of the receiver stations, a time difference of arrival between the first signal and second signal; computing, for each of the receiver stations and based on the corresponding time difference of arrival, an ellipse having a first focal point corresponding to the transmitter station and having a second focal point corresponding to the respective receiver station; determining a plurality of intersection points between pairs of said ellipses; and estimating the location of the client device using said determined intersection points.
• the method of this aspect implements an ellipse-based position location scheme which can allow for efficient location discovery of clients in wireless networks.
• the scheme can use the time difference of arrival (TDOA) between two signals at a plurality of receivers, which are respectively directly received from the transmitter and rebroadcast from the client. By measuring the TDOA of these signals locally at each receiver, geometric relations can be formulated and used in determining the location of the client.
• TDOA time difference of arrival
• the method can typically operate with no communication overhead for the transmitter, client and signal receivers.
• a semi-major axis or a semi-minor axis of each ellipse may be calculated based on the corresponding time difference of arrival for that receiver station.
• the method may include a step of determining a distance, delta(receiveri), which is the distance corresponding to the time difference between the receipt of the first signal and receipt of the second signal at the i th receiver station. This distance can then be used in the computation of an ellipse having the i th receiver station as one of its focal points. This distance can be calculated from the time difference of arrival.
• the method may include a step of calculating, for an i th ellipse corresponding to an i th receiver station, a semi-major axis which is half of the sum of: a) a known distance, distance if f z ) between the respective receiver station and the transmitter station; and b) deltaireceiverf).
• the method may include a step of calculating, for an i th ellipse corresponding to an i th receiver station, an eccentricity e t of the ellipse as:
• the method may include a step of solving, for at least two distinct pairs of the computed ellipses, the following simultaneous equations:
• ( h j , k j ) is the center of the ellipse corresponding to an j th receiver station and is computed based on the foci of the said ellipse receiver station and the transmitter locations; and each (x, y ) satisfying the above simultaneous equations corresponds to the coordinates of an intersection point between the pair of ellipses.
• the computation overhead at the receiver stations and the location management station can be kept very low, as the location detection involves only simple algebraic operations over scalar values.
• the receiver stations may share a common clock.
• each receiver station may include an independently running clock and the clocks of each receiver station may share a nominal frequency.
• the location method of this aspect does not require time (i.e. time-of-day) synchronization between the signal receivers, only the coarse frequency synchronization, typically of the order of tens of parts-per-million (ppm).
• the method can even work for the case where the signal receivers are run asynchronously. In such cases it is preferable that the frequency accuracies of the signal receivers are in the order of not more than, say, 50ppm.
• the transmitter station and the receiver stations may all be transceiver stations, and the method may include a step of: choosing the transmitter station from the transceiver stations by determining a smallest round trip delay from each transceiver station to the client.
• the first signal and the second signal transmitted according to the method of the second aspect may be periodic signals which share the same nominal frequency.
• a signal phase detector circuit which may be within each receiver station, may count at a frequency of f os a number of counts Q between receiver the first signal and receiving the second signal at the respective receiver station, and may calculate the distance
• the phase detector circuit according to the first or second aspects of the invention can be implemented as a pair of D-type master-slave flip-flops or R-S latches.
• An output UP of the circuit may respond only to positive-going edges of the first signal.
• the method of the present aspect may include any combination of some, all or none of the above described preferred and optional features.
• a third aspect of the present invention provides a location management station, connected to a wireless network, and having a processor, wherein the processor is configured to: receive, from each of at least three receiver stations connected to the wireless network, a time difference of arrival measurement, the time difference of arrival measurement being the time difference between the arrival of a first signal and a second signal at the respective received stations, wherein: the first signal is a signal transmitted from a transmitter station; and the second signal is a signal corresponding to the first signal and transmitted from a client device, the transmission of which is triggered by receipt, at the client device, of the first signal; compute, for each of the receiver stations and based on the corresponding time difference of arrival, an ellipse having a first focal point corresponding to the transmitter station and having a second focal point corresponding to the respective receiver station; determine a plurality of intersection points between pairs of said ellipses; and estimate the location of the client device using said determined intersection points.
• the processor of the location management system of this aspect may also be configured to perform any further optional or preferred steps of the above described second aspect.
• a fourth aspect of the present invention provides a client device, connected to a wireless network, and having a controller configured to perform the method of the second aspect.
• Figure 1 shows the architecture of a localization system according to an embodiment of the present invention
• Figure 2 shows sample node layout diagrams for signal receivers and a transmitter in a localization system according to an embodiment of the present invention
• Figure 3 shows the relationship between transmitter and untethered client signals
• Figure 4 shows an example of the phase detector architecture for detecting the difference between transmitter and client signals at a signal receiver
• FIG. 5 shows the operation of the phase detector of Figure 4.
• Figure 6 illustrates the state diagram of the phase detector of Figure 4
• Figure 7 shows a plot of location resolution versus frequency accuracy
• Figure 8 illustrates the general parameters of ellipsoidal geometry and has already been described
• Figure 9 shows the alternative possible intersections and overlaps of two arbitrarily located and oriented ellipses and has already been described;
• Figure 10 illustrates ellipses each with a distinct focus but sharing a common focus and a common point
• Figure 11 illustrates the general location of a potential client with respect to a transmitter and receivers
• Figure 12 shows an example scenario of ellipse-based location determination of a client according to an embodiment of the present invention
• Figure 13 shows a further example scenario of ellipse-based location determination of a client according to an embodiment of the present invention.
• Figure 14 illustrates how the standard parameters of an ellipse are derived and has already been described.
• Embodiments of the present invention provide techniques for determining the location of an untethered wireless client that relays signals from a reference transmitter (or beacon) in a wireless network environment.
• the architecture of a system according to an embodiment of the present invention is shown in Figure 1.
• the network environment contains at least one reference transmitter that sends periodic signals.
• the distance from the transmitter to each signal receiver is assumed to be known and available, that is the device (both transmitter and signal receivers) layout plan in location and distance is known a priori to the network engineer as shown in Figure 2.
• the availability of a common clock at the signal receivers would provide more accurate client location.
• the techniques set out in embodiments of the present invention do not preclude the use of independently running (asynchronous) clocks at the receivers, but such clocks preferably have the same nominal frequency and their frequency deviations are well constrained.
• the signal receivers reference the transmitter and client pulse instances when inferring the distance of a particular client.
• the clients can be distinguished by their respective unique pulse signature (see, for example, Figure 3).
• the location management station calculates the position of target mobiles.
• the location management station sends the mobile's position latitude and longitude calculations through the base station controller (BSC) and mobile switching center (MSC) to gateway mobile location centers for distribution to BSC and mobile switching center (MSC)
• BSC base station controller
• MSC mobile switching center
• the location management station can also manage, coordinate, and administer the location system and provide interfaces to external entities such as network operations and administration centers/systems.
• the location management station may be a dedicated computing device which is separate from, but connected to, the elements of the wireless network, or it may operate within the architecture of the transmitters and/or receivers and/or client(s). There may be a single location management station for the network, or there may be a plurality of such stations which are each capable of operating in this manner. Elements of the location management station may also be distributed across different devices, including the transmitters and/or receivers.
• a location activity is initiated by an application external to the location system itself.
• a gateway mobile location center in response to an application's request for a location (for example, to find a child), screens the request and forwards it through the network to the location management station.
• the location management station usually sends calculated mobile position information through a gateway mobile location center to an external entity, generally the application that initiated the location activity or, in the case of public safety locations, to the appropriate emergency service center/public safety answering point.
• Figure 1 , Figure 2 and Figure 3 show the main features of a location system architecture according to an embodiment of the present invention.
• Features of the architecture of this embodiment include:
• a transmitter 1 that transmits periodic distinguishable signals also at a nominal
• a client 2 which relays the transmitter signal upon receiving it, the relayed signal being distinguishable from that of the transmitter 1.
• the signal receivers are assumed to be frequency synchronized to a
• Frequency synchronization could be achieved by any of the methods described in [1] for Layer 1 or Layer 2 frequency transfer. Note that only frequency synchronization is preferred at the signal receivers and not time synchronization (i.e., wall-clock transfer).
• the signal receivers could be run asynchronously but with each receiver having the same nominal frequency and well constrained deviation from nominal (in parts-per-million, (ppm)).
• the maximum deviation in this case will dictate how accurate the location system will perform.
• a frequency deviation will result in a client location being defined by a cluster of points instead of a single point as will be the case when all receiver frequencies are tightly synchronized.
• the signal receivers each reference the same transmitter and client pulse instances to generate a time difference of arrival (TDOA) between the transmitter signal and the client’s relayed signal.
• TDOA time difference of arrival
• the TDOA is then used to generate a distance difference (or phase distance) between the distance from the transmitter directly to the receiver and the distance from the transmitter indirectly to the receiver through the client.
• Each signal receiver then forwards its distance difference measurement for a particular client to a location management station which executes an algorithm to determine the actual location of the client.
• Each signal receivers employs a phase detector
• the signal receivers 3a-3d are connected to a location management station 4
• the transmitter may also be connected to this network.
• a digital transmitter-client signal phase detector (PD) circuit can be implemented using either D-type master-slave flip-flops or R-S latches.
• Figure 4 shows a PD built with D-type flip-flops.
• the output UP will respond only to the positive-going edges of the input“Transmitter Signal”. Therefore, the input duty cycles do not have any effects on the outputs.
• the operation of a typical PD is illustrated in Figure 5.
• the time value of the differential output, (UP), measured by the high-speed counter is an indication of phase difference between the transmitter signal and client signal.
• the frequency of the high-speed sampling oscillator f os driving the UP/DOWN counter is chosen such that the location system will have a good precision. Given that c is the speed of light in meters per second (299,792,458 meters per second), then the distance traveled in 1/ f os seconds is c/f os meters, which is also the precision of the location system.
• the UP-DOWN counter is a binary counter of certain size whose upper limit can be denoted as Max. Before a reset, the value stored in the counter is latched out.
• the transmitter In the location system the transmitter is assumed to have a nominal frequency.
• the phase difference between the transmitter and the client signals depends on where the client is with respect to transmitter and the receivers. Since in practice the client signals always come after those of the transmitter signals, the DOWN can be fixed at low.
• the time average value of the differential output, (UP) is an indication of phase difference between the two signals.
• UP/DOWN counter also outputs a value with time.
• the PD outputs a positive value implying the transmitter leads the client signal at the signal receiver.
• Figure 6 illustrates the state diagram of the PD.
• the PD can be in one of two states:
• the D-type flip-flops are triggered by the positive-going edges of inputs, transmitter signal and client signal, to the PD. Initially, both outputs are low. When one of the PD inputs rises, the corresponding output becomes high. The state of the finite- state machine (FSM) moves from an initial state to an UP state. The state is held until the second input, the arrival of the client signal, goes high, which in turn resets the circuit and returns the FSM to the initial state.
• FSM finite- state machine
• the slope of the PD counter output is positive and the slope basically stays the same until the next reset.
• the PD is implemented as follows:
• the PD Before the PD counter is reset at signal receiver i , the PD latches out the counter value, , (may be zero or positive only in our application).
• the signal receiver clock is assumed to be good enough to obtain sufficient location resolution. Detailed analysis of the signal receiver clock quality and its impact on the location accuracy is considered in this section.
• Table 1 shows a sample range of location resolution for the frequency range of 50 MHz to 500 MHz with ⁇ 50 ppm.
• the corresponding graph ( Figure 7) shows that location resolution is more sensitive to the choice of frequency magnitude than location accuracy is to the choice of frequency stability.
• the location algorithm uses frequency in two distinct manners.
• the first use is in the signal generation at the transmitter.
• the signal from the transmitter serves as start time markers for all the receivers.
• the signal retransmitted by the client upon the receipt of the transmitter signal serves as the end time markers for all the receivers.
• the location resolution and accuracy of the algorithm do not depend on the stability and the magnitude, i.e. , nominal value, of the frequency used at the transmitter.
• the algorithm does require that these signals be distinguishable by the receivers and their periods not be ambiguous.
• the second use is in the measurement at each signal receiver of the separation of the two time markers described above. In this case, the choice of the frequency source used to make the measurement influences the granularity and the variation of the location resolution.
• the transceiver chosen is preferably the one which is nearest to the client.
• One method to determine is to use ranging from the potential transmitter and the client. The transmitter with the smallest round trip delay is chosen.
• the transmitter period is greater than the time needed to reach the farthest receiver through the client from the transmitter.
• the general location of the client with respect to the receivers can be determined.
• the client can be in one of the two general locations as shown in Figure 11 : on the line segment determined by the transmitter and one of the receivers o this is true if the distance between the foci (transmitter and the receiver) is equal to the sum of the distance between the transmitter and the client, and the distance between the client and the receiver
• FIG. 12 An example of ellipse-based determination of client location is illustrated in Figure 12.
• the transmitter is at (0, 0) denoted by F and the receivers are A, B, D, and E, respectively at (30, 0), (0, 28), (-25, 0) and (0, 40).
• the ellipses formed by F as the common focus, A, B, D, and E as one of the other foci and some further information derived in the manner set out below determine that the client C is at (-6, -8).
• the phase distance delta(receiveri ) at a receiver / ' can be determined and then used together with the corresponding transmitter and receiver locations information to construct the locus of the estimate of the client position.
• the transmitter continuously emits two pulses of distinct signature at a regular time interval that is greater than the time required to reach the farthest receiver through the client from the transmitter.
• the client emits pulses of distinct signature, also different from but correlated to that of the transmitter, upon receipt of each of the transmitter signals.
• the client signal is the signal relayed by the client after having received the transmitter signal.
• the timer value at the arrival of the signal relayed through the client is the time value of deltafreceiveri).
• o b i ⁇ a i Jl - ef o (hi. k j ) computed based on the foci of ellipse i t location(transmitter ) and location(recieveri)
• the following example illustrates, how under certain assumptions, it is possible to obtain a closed form solution for finding the client location.
• the first assumption is that all the ellipses of interest share a common focus which corresponds to the transmitter’s location. (Using multiple transmitters is also possible but this scenario will not be described further herein.)
• the other foci can then be grouped into two pairs.
• the second assumption is that each pair of foci forms the end point a line segment containing the common focus.
• the third assumption is that, without loss of generality, these two line segments are perpendicular to each other.
• intersection points are then given as follows:
• the location of the client is the common point among the following points of E 1 and E z , and
• each receiver consistently determines its time difference of arrival of the transmitter signal relayed by client signal and that of the transmitter signal.
• This information together with the locations of the transmitter and receiver as foci, can be used to formulate an ellipse.
• the client’s location is accordingly the common intersection of the formulated ellipses.
• precise intersection may not arise in every instance, but a common point can be determined or estimated which may, for example, be based in part on the smallest cluster of closest intersection points. For example, the centroid of the convex polygon formed by the said smallest cluster of closest intersection points can be considered as the location estimate.
• the location system still has accurate location resolution even if the signal receivers are run asynchronously, as long as their parts-per-million (ppm) frequency accuracies are within the order of a few tens of ppm around a common nominal value.
• the systems and methods of the above embodiments may be implemented in a computer system (in particular in computer hardware or in computer software) in addition to the structural components and user interactions described.
• computer system includes the hardware, software and data storage devices for embodying a system or carrying out a method according to the above described
• a computer system may comprise a central processing unit (CPU), input means, output means and data storage.
• CPU central processing unit
• the computer system has a monitor to provide a visual output display.
• the data storage may comprise RAM, disk drives or other computer readable media.
• the computer system may include a plurality of computing devices connected by a network and able to communicate with each other over that network.
• the methods of the above embodiments may be provided as computer programs or as computer program products or computer readable media carrying a computer program which is arranged, when run on a computer, to perform the method(s) described above.
• the term“computer readable media” includes, without limitation, any non-transitory medium or media which can be read and accessed directly by a computer or computer system.
• the media can include, but are not limited to, magnetic storage media such as floppy discs, hard disc storage media and magnetic tape; optical storage media such as optical discs or CD- ROMs; electrical storage media such as memory, including RAM, ROM and flash memory; and hybrids and combinations of the above such as magnetic/optical storage media.

Landscapes

• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Position Fixing By Use Of Radio Waves (AREA)
• Mobile Radio Communication Systems (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=60990771

Family Applications (1)

Country Status (2)

Family Cites Families (5)

• 2017
  • 2017-12-22 WO PCT/EP2017/084516 patent/WO2019120582A1/en unknown
  • 2017-12-22 EP EP17829660.4A patent/EP3729131A1/de active Pending

Also Published As

Similar Documents

Legal Events