JP2016148591A - Direction-of-arrival estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that enables discrimination of reflected waves from a direct wave even when a position of an array antenna is fixed.SOLUTION: For each of a plurality of sub-array antennas of an array antenna, each comprising n (1<n<m) antenna elements and being selected such that center positions of the antenna elements in an array direction are different from each other, a first azimuth candidate computation unit (333: S210-S260) derives directions of arrival of all the received incoming waves from a signal received by the sub-array antenna. A direct wave selection unit (333: S270-S280) selects a direct wave arriving directly from a transmission source by comparing the directions of arrival of the incoming waves determined for each of the sub-array antennas by the first azimuth candidate computation unit.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a technique for estimating an azimuth in which a transmitter exists using a wireless communication signal.

  Conventionally, a radio communication signal in a high UHF band (several GHz) transmitted from a system to be measured is received by each element of an array antenna included in the measurement system, and the system to be measured is based on reception intensity and phase information of the received signal. There are known techniques for obtaining the direction of arrival of a radio communication signal from the radio and the relative position of the system under measurement and the measurement system. If there is a reflector that reflects radio waves around the system to be measured and the measurement system, the measurement system reflects not only the direct wave that directly arrives from the system to be measured but also the reflection that arrives after being reflected by the reflector. I also receive waves. Therefore, in order to correctly detect the direction in which the system to be measured is located, it is necessary to identify the direct wave and the reflected wave. As one of the technologies to achieve this, wireless communication signals are received at two different points by moving the measurement system, and direct waves and reflected waves are selected based on angle changes in the direction of arrival of wireless communication signals at both points. A technique is known (see Patent Document 1).

JP 2006-125993 A

  However, the prior art needs to move the position of the measurement system (particularly the array antenna), and there is a problem that it cannot be applied under conditions where the position of the measurement system is fixed.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a technique for realizing selection of reflected waves and direct waves even when the position of the array antenna is fixed.

  The arrival direction estimation apparatus of the present invention estimates the arrival direction of an incoming wave according to received signals from m (m is an integer of 3 or more) antenna elements constituting an array antenna, and calculates a first azimuth candidate. Unit, a direct wave selection unit, and an arrival direction determination unit.

  The first azimuth candidate calculation unit includes a plurality of partial arrays in which the array antennas are each composed of n (1 <n <m) antenna elements and the center positions of the antenna elements in the arrangement direction are different from each other. For each antenna, the arrival direction of the incoming wave is determined according to the received signal from the partial array antenna. The direct wave selection unit selects the direct wave that directly arrives from the transmission source by comparing the arrival directions of the incoming waves obtained for each partial array antenna by the first direction candidate calculation unit. The arrival direction determination unit determines the arrival direction estimation result using the arrival direction of the direct wave selected by the direct wave selection unit.

  According to such a configuration, since a single array antenna is used as a plurality of partial antennas whose center positions are different from each other, received signals at a plurality of points having different positions can be obtained. Direct waves and reflected waves can be selected without moving the antenna.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a block diagram which shows the structure of a position estimation system. It is explanatory drawing which shows the structure of an array antenna and the setting of a partial array antenna. It is a flowchart of a direct wave arrival direction estimation process. It is a flowchart of the direct wave selection process performed in the direct wave arrival direction estimation process. It is explanatory drawing which shows each parameter used for selection of a direct wave and a reflected wave. It is explanatory drawing which shows the other setting method of a partial array antenna.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
[Constitution]
As illustrated in FIG. 1, the position estimation system 1 includes a device under measurement (transmission side device) 2 and a measurement device (reception side device) 3. The device under measurement 2 includes, for example, a mobile phone or a smart key, and the measurement device 3 is configured as an on-vehicle device mounted on a vehicle, for example.

  The device under measurement 2 includes an antenna 21, a transmitter 22, and a communication controller 23. The transmitter 22 transmits a wireless communication signal according to a predetermined communication standard (for example, WiFi (registered trademark) or Bluetooth (registered trademark)) using the high UHF band (several GHz) via the antenna 21. The communication controller 23 controls communication using a wireless communication signal. Hereinafter, the radio wave transmitted by the device under test 2 is also referred to as “designated wave”.

The measuring apparatus 3 includes a first array antenna 31, a second array antenna 32, a first receiving unit 33, a second receiving unit 34, and a position estimating unit 35.
As shown in FIG. 2, each of the first and second array antennas 31 and 32 is m (m is a positive number of 3 or more, m = 8 in the figure) antenna elements E1 to Em arranged in the horizontal direction. It consists of Further, the two array antennas 31 and 32 are arranged at different positions at least in the horizontal direction.

  Returning to FIG. 1, the first receiving unit 33 estimates the arrival direction of the received designated wave according to the received signal from the first array antenna 31, and the first estimation direction DR <b> 1 that is the estimation result is sent to the position estimating unit 35. Supply. The second receiving unit 34 estimates the arrival direction of the received designated wave according to the received signal from the second array antenna 32, and supplies the second estimation direction DR2 that is the estimation result to the position estimating unit 35.

  Since the first receiving unit 33 and the second receiving unit 34 have the same configuration, only the configuration of the first receiving unit 33 will be described here. The first reception unit 33 includes an element switch 331, a receiver 332, and a direct wave arrival direction estimation unit 333. The element switch 331 receives the reception signals from the antenna elements E1 to Em constituting the first array antenna 31, and receives the reception signals from the antenna elements selected according to the instruction from the direct wave arrival direction estimation unit 333. To machine 332. As shown in FIG. 2, the setting for selecting all antenna elements is Y0, the setting for selecting n (n = 4 in the figure) antenna elements from one end (left end in the figure) of the array antenna is Y1, and the array is selected. A setting for selecting n antenna elements from the other end (right end in the figure) of the antenna is denoted as Y2. The array antenna configured by the antenna elements selected by the setting Y1 or Y2 is hereinafter referred to as a partial array antenna. The number of antenna elements constituting the partial array antenna (hereinafter referred to as “number of elements”) n is n = p + 1, where p is the maximum number of incoming waves (total number of direct waves and reflected waves) that may be received simultaneously. Set to

  Returning to FIG. 1, the receiver 332 samples the reception signal supplied via the element switch 331 and supplies the sampled signal to the direct wave arrival direction estimation unit 333. The direct wave arrival direction estimation unit 333 includes a known microcomputer having a CPU, a ROM, and a RAM, and processes a sampled reception signal (hereinafter referred to as reception data) supplied from the receiver 332 to generate a direct wave. A direct wave arrival direction estimation process is performed to estimate the arrival direction.

  The position estimation unit 35 includes a first estimation direction DR1 estimated by the first reception unit 33, a second estimation direction DR2 estimated by the second reception unit 34, and an installation interval between the first array antenna 31 and the second array antenna 32. The position of the device under measurement 2 that is the transmission source of the designated wave is estimated using a known triangulation technique.

[Direct wave arrival direction estimation processing]
Here, the details of the direct wave arrival direction estimation processing executed by the direct wave arrival direction estimation unit 333 will be described with reference to the flowchart shown in FIG. This process is repeatedly started as long as power is supplied from the battery of the vehicle on which the measuring device 3 is mounted.

When this process is activated, the CPU functioning as the direct wave arrival direction estimation unit 333 initializes the setting of the element switch 331 to Y0 in S110.
In continuing S120, it waits until a designated wave is received, and if a designated wave is received, it will progress to S130.

In S130, the arrival directions of all incoming waves are estimated by executing high-resolution azimuth estimation processing such as MUSIC using received signals from all antenna elements.
In subsequent S140, all arrival directions detected by the processing in S120 are stored in the memory as azimuth candidates.

In subsequent S150, a direct wave selection process (described later) for selecting a direct wave is executed using the partial array antenna.
In subsequent S160, among the azimuth candidates stored in S140, the closest arrival direction estimated in S230 to be described later for the incoming wave selected as the direct wave in S150 is used as the direct wave arrival direction estimation result. The process is terminated.

[Direct wave selection processing]
Details of the direct wave selection processing executed in the previous S150 will be described with reference to FIGS.
In this process, as shown in FIG. 4, first, in step S210, the parameter i used for the switching setting of the element switch 331 is initialized to 1.

In subsequent S220, the setting of the element switch 331 is set to Yi.
In continuing S230, it waits until a designated wave is received. When the designated wave is received, the arrival directions θia, θib,... Of the designated wave are estimated using received signals from the respective antenna elements constituting the partial array antenna corresponding to the setting Yi in S240. In addition, the difference of an incoming wave shall be represented by a, b, c, ... (refer FIG. 5).

In subsequent S250, the parameter i is incremented.
In subsequent S260, it is determined whether or not the parameter i is equal to or greater than the number of switching settings of the element switch 331, that is, the number of types of partial array antennas Imax (here, Imax = 2).

  If i <Imax, the process returns to S220 assuming that there is an unprocessed switch setting, and if i ≧ Imax, the process proceeds to S270, assuming that all the switch settings have been processed.

  S270 calculates angle differences Δθa, Δθb,... Of arrival directions detected by the respective partial array antennas for each detected incoming wave a, b,... (See FIG. 5). Whether or not two arrival directions detected by different switching settings are due to the same arrival wave is determined based on whether or not the angle difference between the two arrival directions is within a predetermined range.

  In the case of Imax ≧ 3, i, j = 1 to Imax, i ≠ j, x = a, b, c,..., And for all combinations (i, j) of the switching setting, the angle difference Δθijx = | θix−θjx | is calculated, and an average value or a value determined by majority decision of a plurality of angle differences Δθijx obtained for each incoming wave x is set as the angle difference Δθx of the incoming wave x.

In subsequent S280, in S270, the incoming wave having the maximum angle difference Δθx obtained for each incoming wave is selected as the direct wave, and this process is terminated.
Note that the fact that direct waves and reflected waves can be selected by comparing the angle difference is described in detail in, for example, Patent Document 1, and thus the description thereof is omitted here.

[effect]
As described above, the measuring device 3 constituting the position estimation system 1 uses a single array antenna 31 as a plurality of partial antennas set so that the center positions are different from each other, thereby allowing a plurality of different positions. Since the reception signal at the point is obtained, the direct wave and the reflected wave can be selected without moving the measuring device 3.

  The measuring apparatus 3 selects a direct wave according to the arrival direction of the low resolution estimated using the reception signal from the partial array antenna, and uses the reception signals from all the array antennas as the arrival direction of the direct wave. The direction of arrival with high resolution estimated in this way is used. Thereby, a highly accurate estimation result of the direction of arrival can be obtained.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention can take a various form, without being limited to the said embodiment.

  (1) In the above embodiment, the functions of the direct wave arrival direction estimation unit 333 and the position estimation unit 35 are realized by processing executed by a microcomputer. However, the realization of these units by software is merely an example, and the whole or a part thereof may be implemented by hardware such as a logic circuit.

  (2) In the above embodiment, as the partial array antenna, one that selects n antenna elements from one end of m array antennas and one that selects n antenna elements from the other end are used. In FIG. 2, it is set so as to have a relationship of n = m / 2, but is not limited to this, and as shown in FIGS. 6A and 6B, 2 ≦ n ≦ m−. It can be arbitrarily set within the range of 1. However, as n is increased, the position difference between the two partial array antennas is reduced, so the resolution of the angle difference is degraded. However, the number of incoming waves is increased because the number of elements is increased. The smaller the resolution, the lower the resolution of the angle difference, but the number of detectable incoming waves decreases.

  Further, the partial array antennas do not necessarily have to be set at both ends, and it is sufficient that the center positions of the partial antennas are different. As shown in FIG. 6C, if the total number of elements of the array antenna is m and the number of elements of the partial array antenna is n, (m−n + 1) types of partial array antennas can be set. Any two or more can be used.

  (3) In the above embodiment, the arrival direction obtained using the entire array antenna is set as the direct wave arrival direction. However, the arrival direction obtained using the partial array antenna may be directly used as the direct wave arrival direction. Good.

  (4) In the above embodiment, the element switch 331 is switched according to the setting of the partial array antenna to be used, and the received signal is reacquired for each setting. However, reception of all antenna elements constituting the array antenna is performed. When signals are acquired in a lump and stored in a memory and a process related to a partial array antenna is executed, a stored value of a received signal from a corresponding antenna element may be read and processed. In this case, since the element switch 331 can be omitted, the apparatus configuration can be simplified.

  (5) The functions of one component in the above embodiment may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claim are embodiment of this invention.

  (6) In the present invention, in addition to the arrival direction estimation devices (the first reception unit 33 and the second reception unit 34), a device (measurement device 3) or system (position estimation system 1) including the arrival direction estimation device as a constituent element It can also be realized in various forms.

  DESCRIPTION OF SYMBOLS 1 ... Position estimation system 2 ... Measuring apparatus 3 ... Measuring apparatus 21 ... Antenna 22 ... Transmitter 23 ... Communication controller 31 ... 1st array antenna 32 ... 2nd array antenna 33 ... 1st receiving part 34 ... 2nd receiving part 35 ... Position estimation unit 331 ... Element switcher 332 ... Receiver 333 ... Direct wave arrival direction estimation unit

Claims (6)

An arrival direction estimation device (33, 34) for estimating an arrival direction of an incoming wave according to received signals from m (m is an integer of 3 or more) antenna elements constituting an array antenna (31, 32),
The array antenna is composed of n (1 <n <m) antenna elements, and each of the partial array antennas selected so that the center positions of the antenna elements in the arrangement direction are different from each other. A first azimuth candidate calculation unit (333: S210 to S260) for determining the arrival directions of all incoming waves received according to the received signal from the partial array antenna;
A direct wave selection unit (333: S270 to S270) that selects a direct wave coming directly from the transmission source by comparing the arrival directions of the incoming waves obtained for each of the partial array antennas by the first orientation candidate calculation unit. S280),
An arrival direction determination unit (333: S110 to S140, S160) that determines an estimation result of the arrival direction using the arrival direction of the direct wave selected by the direct wave selection unit;
An arrival direction estimation apparatus comprising:   The direct wave selection unit obtains an angle difference of arrival directions based on the same arrival wave for each arrival direction detected by any two partial array antennas by the first direction candidate calculation unit, and the angle difference is the maximum The arrival direction estimation apparatus according to claim 1, wherein the incoming wave is selected as the direct wave. Three or more partial array antennas are set,
The direct wave selection unit calculates the angle difference for all combinations of the partial array antennas, and selects the direct wave using an average or majority result of the angle difference for each incoming wave. The arrival direction estimation apparatus according to claim 2. The arrival direction determining unit
A second azimuth candidate calculation unit (333: S110 to S140) that estimates an arrival direction of the incoming wave according to reception signals from more antenna elements than the antenna elements that constitute the partial array antenna;
Selection means (333: S160) that selects the closest direction to the arrival direction of the direct wave selected by the direct wave selection unit from the arrival directions calculated by the two-azimuth candidate calculation unit (333: S160) )When,
The direction-of-arrival estimation apparatus according to any one of claims 1 to 3, further comprising:   The number m of the antenna elements is set so as to satisfy m ≧ 2 × (p + 1), where p is a maximum number of assumed reflected waves. The arrival direction estimation device according to item 1.   As the partial array antenna, an antenna using n antenna elements continuous from one end of the array antenna and an antenna using n antenna elements continuous from the other end of the array antenna are used. The arrival direction estimation apparatus according to any one of claims 1 to 5.

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