WO2013130041A1 - Détermination de la direction d'un émetteur sans fil - Google Patents

Détermination de la direction d'un émetteur sans fil Download PDF

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Publication number
WO2013130041A1
WO2013130041A1 PCT/US2012/026877 US2012026877W WO2013130041A1 WO 2013130041 A1 WO2013130041 A1 WO 2013130041A1 US 2012026877 W US2012026877 W US 2012026877W WO 2013130041 A1 WO2013130041 A1 WO 2013130041A1
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WO
WIPO (PCT)
Prior art keywords
antennas
directional antennas
radio signal
group
orientated
Prior art date
Application number
PCT/US2012/026877
Other languages
English (en)
Inventor
Vivek Vishal Shrivastava
Raja Bose
Hawk Yin Pang
Vidya Raghavan Setlur
Quinn Jacobson
Original Assignee
Nokia Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nokia Corporation filed Critical Nokia Corporation
Priority to PCT/US2012/026877 priority Critical patent/WO2013130041A1/fr
Publication of WO2013130041A1 publication Critical patent/WO2013130041A1/fr

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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
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G01S3/28—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics
    • G01S3/32—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics derived from different combinations of signals from separate antennas, e.g. comparing sum with difference
    • G01S3/36—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics derived from different combinations of signals from separate antennas, e.g. comparing sum with difference the separate antennas having differently-oriented directivity characteristics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
    • H01Q1/2216—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in interrogator/reader equipment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
    • H01Q21/20—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a curvilinear path
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/29—Combinations of different interacting antenna units for giving a desired directional characteristic

Definitions

  • the invention relates to apparatuses and methods for determining a direction of a wireless transmitter.
  • Directional antennas can be used to infer the direction of different wireless devices.
  • signal strength measurements can be used to infer the proximity of those devices.
  • this specification describes apparatus comprising an array of directional antennas each orientated in a different direction, at least one processor, and at least one memory, the at least one memory having computer-readable code stored thereon, the computer-readable code, when executed, causing the apparatus to measure a strength of a radio signal received at each of the directional antennas, to compare the strength of the radio signal received at each of the directional antennas with a first signal strength threshold, to identify a first set of at least one directional antennas from the array for which the strength of the received radio signal satisfies a first criterion with respect to the first signal strength threshold, and to determine a direction of a radio signal transmitter based on the direction in which at least one of the first set of directional antennas is orientated.
  • this specification describes a method comprising measuring a strength of a radio signal received at each directional antenna of an array of directional antennas, each directional antenna in the array being orientated in a different direction, comparing the strength of the radio signal received at each of the directional antennas with a first signal strength threshold, identifying a first set of at least one directional antennas from the array for which the strength of the received radio signal satisfies a first criterion with respect to the first signal strength threshold, and determining a direction of a radio signal transmitter based on the direction in which at least one of the first set of directional antennas is orientated.
  • this specification describes computer readable code which, when executed by computing apparatus, causes the computing apparatus to perform a method according to the second aspect.
  • this specification describes a non-transitory computer-readable storage medium having stored therein computer-readable code, which, when executed by computing apparatus, causes the computing apparatus to measure a strength of a radio signal received at each directional antenna of an array of directional antennas, each directional antenna in the array being orientated in a different direction, to compare the strength of the radio signal received at each of the directional antennas with a first signal strength threshold, to identify a first set of at least one directional antennas from the array for which the strength of the received radio signal satisfies a first criterion with respect to the first signal strength threshold, and to determine a direction of a radio signal transmitter based on the direction in which at least one of the first set of directional antennas is orientated.
  • this specification describes apparatus configured to measure a strength of a radio signal received at each directional antenna of an array of directional antennas, each directional antenna in the array being orientated in a different direction, to compare the strength of the radio signal received at each of the directional antennas with a first signal strength threshold, to identify a first set of at least one directional antennas from the array for which the strength of the received radio signal satisfies a first criterion with respect to the first signal strength threshold, and to determine a direction of a radio signal transmitter based on the direction in which at least one of the first set of directional antennas is orientated.
  • this specification describes apparatus comprising at least one processor, and at least one memory, the at least one memory having computer-readable code stored thereon, the computer-readable code, when executed, causing the apparatus to measure a strength of a radio signal received at each directional antenna of an array of directional antennas, each directional antenna in the array being orientated in a different direction, to compare the strength of the radio signal received at each of the directional antennas with a first signal strength threshold, to identify a first set of at least one directional antennas from the array for which the strength of the received radio signal satisfies a first criterion with respect to the first signal strength threshold, and to determine a direction of a radio signal transmitter based on the direction in which at least one of the first set of directional antennas is orientated.
  • this specification describes apparatus comprising means for measuring a strength of a radio signal received at each directional antenna of an array of directional antennas, each directional antenna in the array being orientated in a different direction, means for comparing the strength of the radio signal received at each of the directional antennas with a first signal strength threshold, means for identifying a first set of at least one directional antennas from the array for which the strength of the received radio signal satisfies a first criterion with respect to the first signal strength threshold, and means for determining a direction of a radio signal transmitter based on the direction in which at least one of the first set of directional antennas is orientated.
  • this specification describes a portable computing device comprising apparatus according to any one of the first, fifth, sixth and seventh aspects.
  • Figure 1 is a schematic illustration of an example apparatus for determining the direction of a wireless transmitter
  • Figure 2 is a schematic illustration of an array of directional antennas which forms part of the apparatus of Figure 1;
  • Figure 3A is a flow chart illustrating a method which may be performed by the apparatus of Figure 1;
  • Figure 3B is a schematic of the array of directional antennas which illustrates an aspect of the method of Figure 3A;
  • Figure 4A is a flow chart illustrating another method which may performed by the apparatus of Figure 1;
  • Figure 4B is a schematic of the array of directional antennas which illustrates an aspect of the method of Figure 4A;
  • Figure 5A is a flow chart illustrating another method which may be performed by the apparatus of Figure 1;
  • Figure 5B is a schematic of the array of directional antennas which illustrates an aspect of the method of Figure 5A;
  • Figure 6 is a flowchart illustrating an aspect of the methods of Figures 3A, 4A and 5A;
  • Figure 7 is a flowchart illustrating an alternative aspect of the methods of Figures 3A, 4A and 5A; and
  • Figures 8A and 8B are schematic illustrations of an experimental setup as used by the inventors.
  • Figure 1 is a schematic illustration of an apparatus 1 for determining the direction of a wireless radio transmitter (not shown).
  • the apparatus 1 may be part of a larger device such as a mobile phone, a laptop, a PDA or a tablet computer.
  • the apparatus 1 comprises a plurality of directional antennas 2, a controller 12 and at least one non-transitory computer-readable memory medium 14.
  • the controller 12 is operable to control the operation of the plurality of directional antennas 2 under the control of computer-readable code 14A stored on the at least one memory medium 14.
  • the controller 12 comprises at least one processor 12A which is operable to execute the computer-readable code 14A.
  • the controller 12 may also comprise one or more application-specific integrated circuits (not shown).
  • the at least one memory medium 14 may comprise one or more distinct memory mediums, such as but not limited to ROM, RAM and flash memory.
  • Figure 2 is a schematic illustration of the plurality of directional antennas 2 of Figure 1.
  • the plurality of directional antennas 2 which may be referred to as an array, comprises N directional antennas 20-1, 20-2, 20-3 ... 20-N each orientated in a different direction.
  • the N directional antennas are distributed along a path.
  • the N directional antennas are distributed along a closed path. In the example of Figure 2, the closed path is circular.
  • the N directional antennas 20-1, 20-2, 20-3 ... 20-N are arranged around a reference point 22.
  • the array 2 comprises 18 antennas 20-1, 20-2... 20- 18.
  • N 18
  • the directional antennas 20-1, 20- 2, 20-3 ... 20-N are equally spaced around the reference point 22.
  • the angular separations between each antenna 20-1 and its two neighbouring antennas 20-N, 20-2 are equal to one another.
  • Neighbouring antennas may also be referred to as adjacent antennas or successive antennas.
  • the directional antennas 20- l, 20-2 ... 20-N are arranged in a circle with the reference point being at the centre of the circle 22.
  • the plurality of directional antennas 2 may be provided in a common plane.
  • Each directional antenna 20-1, 20-2, 20-3 ... 20-N is oriented in a radial direction relative to the reference point 22.
  • each directional antenna 20-1, 20-2, 20-3 ... 20-N is oriented directly away from the reference point 22.
  • Each of the directional antennas 20-1, 20-2, 20-3 ... 20-N is controllable by the controller 12.
  • the controller 12 is operable, under the control of the computer-readable code 14A, to process radio signals received at each of the directional antennas 20-1, 20-2, 20-3 ... 20- N individually.
  • Figure 3A is a flowchart illustrating a first example of a method for determining the position of a wireless radio transmitter.
  • the method of Figure 3A may be caused to be performed by the controller 12 under the control of the computer-readable code 14A.
  • the controller 12 switches on each of the directional antennas 20-1 ... 20-N.
  • the directional antennas 20-1 ... 20-N are operable to receive data packets in the form of radio signals transmitted by the radio transmitter 30 (see Figure 3B), the direction of which is being determined.
  • the controller 12 may switch on each of the directional antennas sequentially or simultaneously. If they are switched on sequentially, it can be said that the antennas are rotated between.
  • step S3.2 the controller 12 determines for one of the directional antennas 20-1 ... 20- N whether the number of data packets received by the directional antenna 20-1 ... 20-N is above a threshold number of data packets.
  • step S3.2 If a negative determination is reached in step S3.2, the operation proceeds to step S3.3 in which the antenna 20-1 ... 20-N which has received fewer than the threshold number of packets is disregarded. After this, at step 83.4a, the next antenna is selected and the method returns to step S3.2.
  • step S3.4 an indication, or measure, of the radio signal strength (RSSI) of the data packets received by the antenna 20-1 ... 20-N is determined.
  • the RSSI may be determined using the signal strength of the single data packet having the largest signal strength. Alternatively, it may be determined using the median signal strength for all data packets received at that antenna 20-1 ...20-N. Alternatively, the RSSI for a particular antenna may be determined using the mean signal strength for all data packets received by that directional antenna 20-1 ...20-N.
  • the controller 12 may be operable to disregard any data packets for which the signal strength is erratic.
  • Data packets having an erratic signal strength may be a result of moving objects nearby or due to movement of the apparatus 1 or the wireless transmitter 30 during reception or transmission of the data packet.
  • Erratic packets can be filtered and discarded using simple techniques. For example, the standard deviation of the signal strengths of all data packets received by a particular antenna 20-1 ...20-N may be calculated and any packets which are more than a certain number of standard deviations away from the mean signal strength may be disregarded for the purpose of calculating the RSSI of the antenna 20-1 ...20-N.
  • step S3.5 it is determined whether the last antenna has been processed. If not, at step 83.5a, the next antenna is selected and then steps S3.2 to S3.4 are repeated for this next directional antenna 20-1 ...20-N.
  • step S3.5 reveals that the RSSI has been calculated for each antenna 20-1 ...20-N for which a positive determination was produced in step S3.2
  • the method proceeds to steps S3.6, S3.6a and S3.7.
  • the controller 12 determines which of the antennas 20-1 ...20-N have an RSSI satisfying a particular criterion.
  • the criterion is that the value of the RSSI must be within a determined confidence interval of the RSSI of the antenna 20-1 ...20-N which has the highest RSSI. This value of the highest RSSI is hereafter referred to as MAX_RSSI.
  • step S3.6 the controller 12 determines the MAX_RSSI.
  • step S3.6a the controller 12 compares the RSSI for each antenna with a threshold defined by MAX_RSSI minus a particular confidence interval. Based on the comparison of step S3.6a, the controller 12 identifies in step S3.7 those antennas 20-1 ...20-N for which the RSSI is within the confidence interval of MAX_RSSI (i.e. is above the threshold).
  • the confidence interval may be for example 3-4 decibel milliwatts.
  • the exact value of the confidence interval may be determined by the controller 12 empirically.
  • the confidence interval may be higher for situations in which the variation in RSSIs of the antennas is larger and may be smaller in situations wherein the variation in RSSIs is smaller.
  • Those antennas 20-1 ...20-N for which the RSSI satisfies this specific criterion are hereafter referred as the HIGH_SET antennas.
  • one or more clusters, or groups, of HIGH_SET antennas is identified based on the relative locations of the HIGH_SET antennas.
  • a cluster of antennas consists of a succession of adjacent antennas for which the criterion is satisfied (in this example, antennas which are members of HIGH_SET).
  • a cluster may be interspersed with antennas for which the criterion is not satisfied. By allowing clusters of antennas for which the criterion is satisfied to be interspersed with antennas for which it is not satisfied, the error in the direction determination caused by data packets having an erratic RSSI may be reduced.
  • a cluster may comprise just a single antenna.
  • Figures 6 and 7 illustrate in more detail examples of processes by which the controller 12 identifies clusters of antennas. These are described below.
  • step S3.9 it is determined if the number of clusters returned in step S3.8 is equal to one. If the determination is negative, the operation returns to step S3.1. If the determination is positive, the operation proceeds to step S3.10.
  • step S3.10 the direction D of the wireless transmitter 30 is determined based on the directions in which each of the directional antennas in the identified cluster is orientated. The direction D is determined by identifying a direction between the directions of the two antennas in the cluster which are separated by the largest angle. This is described in more detail with reference to Figure 3B. Where a cluster comprising a single antenna has been identified, the direction D may be determined as the direction in which the single antenna is orientated.
  • Table 1 shows an example distribution of RSSI values detected by the antennas 20-1...20-N in the array 2.
  • FIG 3B is an illustration of the way in which the direction D of the wireless transmitter 30 is determined.
  • the RSSI values are as shown in Table 1, and that the confidence interval C is 4dBm.
  • the RSSI_MAX is -lodBm.
  • Those antennas which are within the confidence interval (4dBm) of RSSI_MAX i.e. the HIGH_SET antennas
  • the HIGH_SET antennas are denoted by vertical hatching.
  • the non- HIGH_SET antennas are not hatched.
  • the HIGH_SET antennas are located in a single cluster.
  • the direction D of the wireless transmitter 30 is determined by identifying a direction between the directions of the two antennas in the cluster that are separated by the largest angle. More specifically, the direction D is determined by identifying the bisector of the angle between the directions of the two antennas in the cluster that are separated by the largest angle. In this example, these antennas are the fourth and sixth antennas 20-4, 20-6. Consequently, the determined direction D of the wireless transmitter 30 happens to coincide with the orientation of the fifth directional antenna 20-4.
  • the direction D of the wireless transmitter may determined by identifying the mean of the directions of all antennas in the cluster.
  • the direction may be determined by identifying the direction of the sum of the vectors of the directions of all antennas in the cluster.
  • Figure 4A is a flowchart illustrating an alternative method by which the apparatus 1 can detect the direction of a wireless transmitter 30.
  • steps S4.1 to 84.5a are the same as steps S3.1 to 83.5a respectively as described in relation to Figure 3A.
  • the controller 12 determines which of the antennas 20-1 ...20-N have an RSSI satisfying a particular criterion.
  • the criterion is that the value of the RSSI must be within a determined confidence interval of the RSSI of the antenna 20-1 ...20-N having the lowest RSSI.
  • the value of the lowest RSSI is hereafter referred to as RSSI_MIN.
  • step S4.6 the controller 12 determines the RSSI_MIN.
  • step S4.6a the controller 12 compares the RSSI for each antenna with a threshold defined by MIN_RSSI plus a confidence interval. Based on the comparison of step S4.6a, in step S4.7, the controller 12 identifies all the directional antennas 20-1 ...20-N for which the measured RSSI is within the confidence interval of the RSSI_MIN (i.e. is below the threshold).
  • the confidence interval may be determined based on the variation in all measured RSSIs. The plurality of antennas for which the measured RSSI is within the confidence interval from the
  • RSSI_MIN are hereafter referred to as LOW_SET antennas.
  • step S4.8 the controller 12 identifies one or more clusters of LOW_SET antennas. This may be carried out as described below with reference to Figures 6 and 7.
  • step S4.9 it is determined if the number of clusters of LOW_SET antennas is equal to one. If a negative determination is reached, the method returns to step S4.1. If a positive determination is reached, the controller 12, in step S4.9, determines the direction D of the wireless transmitter 30 based on the orientations of the directional antennas within the single cluster. As in step S3.9, the direction D is determined by identifying a direction between the directions of the two antennas that are separated by the largest angle. However, in this example, the direction D is determined by taking the opposite of the identified direction.
  • FIG 4B is an illustration of the way in which the direction D of the wireless transmitter 30 is determined in step S4.9.
  • the RSSI values are as shown in Table 1 above, and that the confidence interval C is 4dBm.
  • the RSSI_MIN is -lodBm.
  • Those antennas which are within the confidence interval (4dBm) of RSSI_MIN i.e. the LOW_SET antennas
  • the LOW_SET antennas are denoted by cross-hatching.
  • the non- LOW_SET antennas are not hatched.
  • the LOW_SET antennas are located in a single cluster.
  • the direction D of the wireless transmitter 30 is determined by identify a direction between the directions of the two antennas that are separated by the largest angle, and taking its opposite. More specifically, direction D is determined by calculating the opposite of the angular bisector of the separation between the directions of the antennas in the cluster that are separated by the largest angle. In this example, these antennas are the twelfth and sixteenth antennas 20-12, 20-16. The direction of the angular bisector is the direction of the fourteenth antenna 20-14. The direction D of the wireless transmitter 30 is determined to be the opposite of this which, in this example, is the direction of the fifth antenna 20-5.
  • the direction D may be determined by identifying the opposite of the mean of the directions of all of the antennas in the cluster. In other words, the direction D may be determined by identifying the opposite of the direction of the sum of the vectors of the directions of all antennas in the cluster. In examples in which the cluster is constituted by a single antenna, the direction D is be determined by identifying the opposite of the direction in which the single antenna is orientated.
  • Figure 5A is flow chart illustrating an example of another method by which the apparatus 1 of Figure 1 is operable to determine the direction D of a wireless transmitter 30.
  • the apparatus 1 is operable to determine the direction D of the wireless transmitter using the orientations of a first group of antennas for which the RSSI satisfies a first criterion and/or the orientations of a second group of antennas for which the RSSI satisfies a second criterion.
  • Steps S5.1 to 85.5a are the same as steps S3.1 to 83.5a respectively as described with reference to Figure 3A.
  • Steps S5.6, S5.6a, S5.7 and S5.8 are the same as steps S3.6, S3.6a, 3.7 and S3.8 respectively as described in relation to Figure 3A.
  • the controller 12 determines the MAX_RSSI (step S5.6), compares the RSSI for each antenna with a threshold based on the MAX_RSSI (Ss.6a), identifies the HIGH_SET antennas based on the comparison (step S5.7), and identifies one or more groups or clusters of the
  • step S5.9 determines the MIN_RSSI (in step S5.9), compares the RSSI for each antenna with a threshold based on the MIN_RSSI (85.9a), identifies the LOW_SET antennas (in step S5.10) and based on the comparison identifies one or more groups or clusters of antennas (in step S5.11).
  • step 85.9a may comprise comparing with the threshold the RSSI's of only those antennas which were not identified as being members of the HIGH_SET.
  • step S5.12 the controller 12 determines if only one set of HIGH_SET antennas has been returned in step S5.8. If a positive determination is reached, the method proceeds to step S5.13 in which the direction D of the wireless transmitter is determined. This direction D is determined as described with reference to Figure 3B.
  • step S5.14 the controller 12 determines if the number of clusters of LOW_SET antennas is equal to one. If a positive determination is reached, the controller 12 proceeds to step S5.13 in which the direction D of the wireless transmitter 30 is determined. The determination is carried out as described with reference to Figure 4B. If a negative determination is reached, the controller 12, in step S5.15, determines a direction based on each of the clusters of HIGH_SET antennas. This is determined by taking the direction of the angular bisector of the angle between the outermost antennas of each cluster.
  • step S5.16 the controller 12 determines a respective direction for each cluster of LOW_SET antennas. This is carried out by taking the opposite of the direction of the angular bisector of the angular separation between the two outermost antennas in each cluster.
  • step S5.17 the controller 12 determines if any of the directions calculated using the clusters of HIGH_SET antennas is equal to a direction calculated using one of the clusters of LOW_SET antennas. If a positive determination is reached, the controller 12 proceeds to step S5.13 in which the direction D of the wireless transmitter is determined. Specifically, the controller 12 determines the direction that is common to a cluster of HIGH_SET antennas and a cluster of LOW_SET antennas to be the direction D of the wireless transmitter 30.
  • step S5.17 If a negative determination is reached in step S5.17, the controller 12 returns to step S5.1 in which the method is started again.
  • Figure 5B illustrates the way in which the controller 12 determines the direction D of the wireless transmitter using the orientations of HIGH_SET antennas and LOW_SET antennas.
  • Table 2 shows another example distribution of RSSI values detected by the antennas 20-1...20-N in the array 2. These values are used in the illustration of Figure
  • RSSI_MAX is -i2dBm and RSSI_MIN is -4idBm.
  • the confidence interval for the example of Figure 5B is 4dBm.
  • There are two clusters of HIGH_SET antennas i.e. antennas for which RSSI_MAX - RSSI_antenna ⁇ C), which are denoted by vertical hatching.
  • There are also two clusters of LOW_SET antennas i.e. antennas for which RSSI_antenna - RSSI_MIN ⁇ C), which are denoted by cross- hatching.
  • a first cluster of HIGH_SET antennas is formed by the sixth and seventh antennas 20-6, 20-7 and the second cluster is formed by the ninth and tenth antennas 20-9, 20-10.
  • a first cluster of LOW_SET antennas is formed by the twelfth and thirteenth antennas 20-12, 20-13 and the second cluster is formed by the fifteenth and sixteenth antennas 20-15, 20-16.
  • the directions calculated using the orientations of the antennas in the first and second clusters of the HIGH_SET antennas are denoted Dcm and DCH2. The directions calculated using orientations of the clusters from the
  • LOW_SET antennas are denoted DCLI and DCL 2 .
  • the direction DCL 2 calculated using the second cluster of the LOW_SET antennas is equal to the direction Dcm calculated using the first cluster of the HIGH_SET antennas. Consequently, the controller 12 determines this direction to be the direction D of the wireless transmitter 30.
  • FIG. 6 is a flowchart illustrating an example of a method by which the controller 12 identifies adjacent clusters or groups of antennas. This method may be used to perform steps S3.8, S4.8, S5.8 and S5.11.
  • an antenna counter i is set to zero. The value of the antenna counter indicates the number of the directional antenna that is being considered. For example, when 2 is equal to one, the first directional antenna 20-1 is being considered and when 2 is equal to twelve, the twelfth directional antenna 20-12 is being considered.
  • step S6.2 a current cluster field (CUR_CLUS) for temporarily storing indicators of antennas which are part of a current cluster is emptied.
  • CUR_CLUS current cluster field
  • step S6.3 the antenna counter 2 is incremented by one.
  • step S6.4 the controller 12 determines if the antenna indicated by the antenna counter (A_i) is a member of the set of interest.
  • the HIGH_SET is the set of interest.
  • step S6.4 would comprise determining if the antenna indicated by the antenna counter 2 is a member of the HIGH_SET.
  • the LOW_SET is the set of interest
  • step S6.4 If it is determined in step S6.4 that the current antenna 2 is a member of the set of interest, the method proceeds to step S6.5 in which an indicator identifying the current antenna is added to the current cluster field.
  • step S6.6 the controller 12 determines if the antenna counter is equal to N (i.e. if it indicates the final antenna in the array). If a negative determination is reached, the method returns to step S6.3 in which the antenna counter 2 is incremented by one.
  • step S6.4 is performed in respect of the next antenna (i.e. the antenna indicated by the incremented antenna counter).
  • step S6.7 the controller 12 determines if the number of antennas indicated by the current cluster field is greater than zero. If it is determined that the number of antennas indicated by the current cluster field is greater than zero (i.e. that at least one antenna is indicated by current cluster field), the method proceeds to step S6.8.
  • step S6.8 the controller 12 adds the cluster indicated by the current cluster field to a list of possible clusters (POSS_CLUS).
  • step S6.9 it is determined if the current antenna i is the last antenna in the array 2. If a negative determination is reached, the method returns to step S6.2 in which the current cluster field is emptied. If a positive determination is reached, the method proceeds to step S6.10.
  • step S6.ii it is determined if the first antenna 20-1 is also member of the set of interest. If a positive determination is reached, the method proceeds to step S6.12, in which the current cluster (those antennas indicated by the current cluster field) is merged with the possible cluster which includes the first antenna (A_i_CLUS). The reason for this is that the first and last antennas 20-1, 20-N are located adjacent to one another and so, if both are members of the set of interest, they should be in the same cluster.
  • step S6.11 If a negative determination is reached in step S6.11, the method proceeds to step S6.13. In step S6.13, it is determined if the number of antennas indicated by the current cluster field is greater than zero. If a positive determination is reached, the method proceeds to step S6.14 in which the current cluster is added to a list of possible clusters. If a negative determination is reached, the method proceeds to S6.10.
  • step S6.10 the controller 12 sorts the clusters identified in the list of possible clusters based on number of antennas per cluster (i.e. the size S of the cluster).
  • step S6.15 the controller 12 determines the size S of the largest group or cluster (MAX_S).
  • step S6.16 all clusters having a size S equal to MAX_S are returned or output. It will thus be understood that only those clusters of antennas having a size equal to MAX_S are considered for the purpose of determining the direction D of the wireless transmitter 30.
  • the method for identifying clusters of antennas as described with reference to Figure 6 does not allow antennas in a cluster to be interspersed with antennas which are not members of the set of interest. As such, erratic RSSI measurements may adversely affect the determination of the direction of wireless transmitters 30.
  • FIG. 7 is an example of an alternative method for identifying clusters whilst reducing the impact of erratic RSSI measurements on the determination of the direction D of the wireless transmitter 30.
  • the antenna counter i is set to zero.
  • a current gap counter (CUR_GAP) is set to zero.
  • the current gap counter indicates the number of successive adjacent antennas which have not been identified in step S7.5 as being in the set of interest (i.e. HIGH_SET or LOW_SET).
  • the current cluster field (CUR_CLUS) is emptied. This is the same as step S6.2 of Figure 6.
  • step S7.4 the antenna counter is incremented.
  • step S7.8 the method proceeds to step S7.8.
  • Steps S7.8 to S7.13 are the same as steps S6.7 to S6.12 respectively, and so, for conciseness, a full description of these steps is not repeated here.
  • the method proceeds to step S7.14 in which the current gap counter is incremented by one.
  • step S7.15 it is determined if the current gap counter is greater than an allowed gap threshold (GAP_TH).
  • GAP_TH allowed gap threshold indicates the number of adjacent antennas which are not members of the set of interest that are allowed to be interspersed in a cluster.
  • the method proceeds to step S7.16 in which it is determined if the number of antennas in the current cluster is greater than zero. If so, the current cluster of antennas is added to the list of possible clusters in step S7.17.
  • step S7.20 it is determined if the number of antennas in the current cluster is greater than zero. If a negative determination is returned (i.e. if the number of antennas in the current cluster field is zero), the method proceeds to step S7.11. If it is determined that the number of antennas in the current cluster is greater than zero, the method proceeds to step S7.21.
  • a second antenna counter j is set to equal one. Subsequently, in step S7.22, it is determined if the antenna identified by the second antenna counter (A_j) is a member of the set of interest.
  • step S7.22 If in step S7.22 a positive determination is reached, the method proceeds to step S7.23 in which the current cluster is merged with the possible cluster which includes the antenna identified by the second antenna counter. If a negative determination is reached, the method proceeds to step S7.24.
  • step 7.24 it is determined if the sum of the current gap counter and the second antenna counter is greater than the gap threshold. If a positive determination is reached, the method proceeds to step 87.24a in which the current cluster of antennas is added to the list of possible clusters. After this, the method proceeds to step S7.11. If a negative determination is reached in step S7.24, the method proceeds to step S7.25 in which the second antenna counter is incremented by one. After this, the method returns to step S7.22.
  • Steps S7.22, S7.24 and S7.25 are repeated until it is determined in step S7.22 that A_j is a member of the set of interest or it is determined in step S7.24 that the sum of the current gap counter CUR_GAP and the second antenna counter j is greater than the allowed gap threshold.
  • the antenna grouping method of Figure 7 allows antennas in an identified cluster of antennas to be interspersed with antennas which are not members of the set of interest. Consequently, the impact of erratic RSSI measurements may be reduced.
  • steps S3.2 to S3.4 may be performed in respect of each antenna simultaneously.
  • step S3.1 (and its equivalents) may comprise activating just one of the antennas. The step may then be repeated in step S3.5 (or its equivalents) for each antenna.
  • step S5.12 may be performed immediately following step S5.8, and steps S5.9 to S5.11 may be omitted if a positive determination is reached in step S5.12.
  • steps S5.9 to S5.11 may be performed before or concurrently with steps S5.6 to S5.8.
  • step S5.14 may be immediately following step S5.11 and steps S5.6 to S5.8 may be omitted if a positive determination is reached in step S5.11.
  • step S5.6a may comprise comparing with the threshold the RSSI's of only those antennas which were not identified as being members of the LOW_SET.
  • steps S5.12 and S5.14 may be reversed.
  • steps S6.7 and S6.13 of Figure 6 may comprise determining if the number of antennas in the current cluster is greater than one.
  • step S7.16 of Figure 7 may comprise determining if the number of antennas in the current cluster is greater than one.
  • step 87.24a of Figure 7 is omitted.
  • all clusters are constituted by plural antennas.
  • Figures 8A and 8B illustrate aspects of an experimental setup that was used by the inventors. Specifically, Figure 8A shows an experimental array 7 of directional antennas 70-1, 70-2, 70-3, ... 70-6. It also shows the locations of the wireless transmitter 74-1, 74- 2, 74-2, 74-3, 74-4 relative to the array 7 at which RSSI measurements were made.
  • the array of directional antennas 7 comprises six directional antennas 70-1, 70-2, 70-3, ... 70-6 spaced equidistantly around a central reference point 72. Each of the directional antennas 70-1, 70-2, 70-3, ... 70-6 is oriented directly away from the reference point 72.
  • the wireless transmitter used during the experiment was a Nokia N900 mobile telephone. The measurements were taken at four locations 74-1, 74-2, 74-2, 74-3, 74-4 around the antenna array 7. For each location, a measurement was taken with the mobile telephone in three different orientations relative to a radial axis of the antenna array upon which the mobile telephone was situated. The three orientations are illustrated in Figure 8B. The radial axis is shown by the dotted line labelled 78. These orientations are perpendicular 76-1 to the radial axis 78, horizontal 76-2 to the radial axis 78 and reverse horizontal 76-3 to the radial axis 78 (i.e. horizontal but rotated by
  • Table 4 shows, for each distance from the array, the number of measurements out of twelve which yielded the correct direction of the mobile telephone.
  • the second column shows the number of correct directions that were determined using only the directional antenna which received the maximum RSSI.
  • the third column shows the number of correct determinations when a method according to Figures 3A and 6 was utilised to determine the direction D of the remote transmitter.
  • the correct direction of the wireless transmitter was determined with far greater success when a method according to the examples described herein were utilised.

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

Abstract

L'invention concerne un appareil comportant un réseau d'antennes directionnelles dont chacune est orientée dans une direction différente, au moins un processeur et au moins une mémoire, un code lisible par ordinateur étant stocké sur la ou les mémoires, le code lisible par ordinateur amenant, lorsqu'il est exécuté, l'appareil à mesurer la force d'un signal radio reçu sur chacune des antennes directionnelles, à comparer la force du signal radio reçu sur chacune des antennes directionnelles à un premier seuil de force du signal, à identifier un premier ensemble d'au moins une antenne directionnelle du réseau pour laquelle la force du radio signal reçu satisfait un premier critère par rapport au premier seuil de force du signal et à déterminer la direction d'un émetteur de signal radio sur la base de la direction dans laquelle au moins une antenne du premier ensemble d'antennes directionnelles est orientée.
PCT/US2012/026877 2012-02-28 2012-02-28 Détermination de la direction d'un émetteur sans fil WO2013130041A1 (fr)

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Publication number Priority date Publication date Assignee Title
CN109143163A (zh) * 2018-08-06 2019-01-04 西南石油大学 一种基于无线信号强度定位的室内定位方法及装置
US11002821B2 (en) 2018-08-22 2021-05-11 Chiun Mai Communication Systems, Inc. Measurement method for measuring millimeter wave signal and measurement device using the same
CN114630020A (zh) * 2020-12-10 2022-06-14 日本电产科宝株式会社 摄像装置和保存有程序的存储装置

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EP0023606A1 (fr) * 1979-07-19 1981-02-11 Siemens Aktiengesellschaft Système d'antennes pour le repérage d'une source de signaux de micro-ondes
WO2000065372A2 (fr) * 1999-04-27 2000-11-02 Brian De Champlain Systeme de poursuite sans fil utilisant un seul recepteur
GB2402553A (en) * 2003-06-06 2004-12-08 Westerngeco Seismic Holdings Segmented antenna system for offshore radio networks and method of using the same
US20080014902A1 (en) * 2006-07-13 2008-01-17 Tranwo Technology Corp. Handheld radio signal tracker
US20080266106A1 (en) * 2007-04-30 2008-10-30 Gwangju Institute Of Science And Technology Navigation apparatus and method using rfid
WO2009086212A1 (fr) * 2007-12-19 2009-07-09 Cobham Defense Electronics Systems Corporation Indication de direction d'objet par l'utilisation de multiples faisceaux d'antenne

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EP0023606A1 (fr) * 1979-07-19 1981-02-11 Siemens Aktiengesellschaft Système d'antennes pour le repérage d'une source de signaux de micro-ondes
WO2000065372A2 (fr) * 1999-04-27 2000-11-02 Brian De Champlain Systeme de poursuite sans fil utilisant un seul recepteur
GB2402553A (en) * 2003-06-06 2004-12-08 Westerngeco Seismic Holdings Segmented antenna system for offshore radio networks and method of using the same
US20080014902A1 (en) * 2006-07-13 2008-01-17 Tranwo Technology Corp. Handheld radio signal tracker
US20080266106A1 (en) * 2007-04-30 2008-10-30 Gwangju Institute Of Science And Technology Navigation apparatus and method using rfid
WO2009086212A1 (fr) * 2007-12-19 2009-07-09 Cobham Defense Electronics Systems Corporation Indication de direction d'objet par l'utilisation de multiples faisceaux d'antenne

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109143163A (zh) * 2018-08-06 2019-01-04 西南石油大学 一种基于无线信号强度定位的室内定位方法及装置
US11002821B2 (en) 2018-08-22 2021-05-11 Chiun Mai Communication Systems, Inc. Measurement method for measuring millimeter wave signal and measurement device using the same
TWI735933B (zh) * 2018-08-22 2021-08-11 群邁通訊股份有限公司 毫米波訊號的測量方法及裝置
CN114630020A (zh) * 2020-12-10 2022-06-14 日本电产科宝株式会社 摄像装置和保存有程序的存储装置

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