JP6538366B2 - Direction of arrival estimation device - Google Patents

Description

  The present invention relates to a technique for estimating the direction in which a transmitter is present using a wireless communication signal.

  Conventionally, the wireless communication signal in the high UHF band (several GHz) transmitted from the system under test is received by each element of the array antenna of the measurement system, and the system under test is based on the reception strength and phase information of the received signal. There is known a technique for obtaining an arrival direction of a wireless communication signal from the sensor and a relative position of a measurement system and a measurement system. Then, if there is a reflector that reflects radio waves around these measured systems and measurement systems, in the measurement system, not only direct waves coming directly from the measured systems but also reflections that are reflected from the reflectors and then come I also receive waves. Therefore, in order to correctly detect the direction in which the measured system is located, it is necessary to distinguish between the direct wave and the reflected wave. As one of the techniques to realize this, by moving the measurement system, wireless communication signals are received at two different points, and the direct wave and the reflected wave are sorted from the angle change of the arrival direction of the wireless communication signal at both points A technology is known (see Patent Document 1).

JP, 2006-125993, A

  However, the prior art needs to move the position of the measurement system (in particular, the array antenna), and can not be applied under the condition where the position of the measurement system is fixed.

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

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

  The first orientation candidate calculation unit is a plurality of partial arrays in which the array antenna is selected such that each includes 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 of the antennas, 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 arrival waves obtained for each partial array antenna in the first direction candidate calculation unit. The arrival direction determination unit determines the estimation result of the arrival direction using the arrival direction of the direct wave selected by the direct wave selection unit.

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

  In addition, the code | symbol in the parentheses described in the claim shows 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 showing composition of a position presumption 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 a direct wave selection process performed during a direct wave arrival direction estimation process. It is an explanatory view showing each parameter used for classification 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]
The position estimation system 1 includes a device to be measured (transmission side device) 2 and a measurement device (reception side device) 3 as shown in FIG. The device to be measured 2 includes, for example, a mobile phone, a smart key, and the like, and the measuring device 3 is configured as, for example, an on-vehicle device mounted on a vehicle.

  The device under test 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) through 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 a “designated wave”.

The measuring device 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, the first and second array antennas 31, 32 each have 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, both array antennas 31 and 32 are disposed at different positions at least in the horizontal direction.

  Referring back 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 transmits the estimated first direction DR 1, which is the estimation result, to the position estimating unit 35. Supply. The second receiving unit 34 estimates the arrival direction of the received designated wave in accordance with the received signal from the second array antenna 32, and supplies the second estimated direction DR2 that is the estimation result to the position estimating unit 35.

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

  Returning to FIG. 1, the receiver 332 samples the reception signal supplied via the element switching unit 331 and supplies it to the direct wave arrival direction estimation unit 333. The direct wave arrival direction estimation unit 333 is formed of a known microcomputer having a CPU, a ROM, and a RAM, and processes the sampled received signal (hereinafter referred to as received data) supplied from the receiver 332 to thereby generate a direct wave. Execute direct wave arrival direction estimation processing to estimate the arrival direction of

  The position estimation unit 35 estimates the first estimated direction DR1 estimated by the first receiver 33, the second estimated direction DR2 estimated by the second receiver 34, and the installation interval of the first array antenna 31 and the second array antenna 32. The position of the device to be measured 2 which is the transmission source of the designated wave is estimated using a known triangulation method according to the above.

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

When this process starts, 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 the following S120, the process waits until the designated wave is received, and when the designated wave is received, the process proceeds to S130.

In S130, high resolution azimuth estimation processing such as MUSIC is performed using the reception signals from all antenna elements to estimate the arrival directions of all incoming waves.
At S140, all incoming directions detected by the process at S120 are stored in the memory as azimuth candidates.

At S150, the partial array antenna is used to execute a direct wave selection process (described later) for selecting a direct wave.
In the following S160, among the direction candidates stored in S140, for the arrival wave selected as the direct wave in S150, the one closest to the arrival direction estimated in S230 described later is the estimation result of the arrival direction of the direct wave. It decides and ends this processing.

[Direct wave selection process]
The details of the direct wave selection process executed in S150 above will be described with reference to FIGS. 4 and 5.
In this process, as shown in FIG. 4, first, at S210, the parameter i used for the switching setting of the element switching device 331 is initialized to one.

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

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

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

  In S270, angle differences Δθa, Δθb,... Of the directions of arrival detected by the partial array antennas are calculated for each of the detected arrival waves a, b,. Note that whether or not the two incoming directions detected with different switching settings are due to the same incoming wave is determined depending on whether or not the angle difference between the two incoming directions is within a predetermined range.

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

In the subsequent S280, in S270, an incoming wave with the largest angular difference Δθx obtained for each incoming wave is selected as a direct wave, and the present process is ended.
The fact that direct waves and reflected waves can be sorted by comparing the difference in angle is described in detail in, for example, Patent Document 1, and therefore the description thereof is omitted here.

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

  Also, in the measuring device 3, direct waves are selected according to the low resolution arrival direction estimated using the reception signal from the partial array antenna, and the reception signals from all array antennas are used as the arrival direction of the direct wave. It uses the high-resolution arrival direction estimated by This makes it possible to obtain highly accurate estimation results of the direction of arrival.

[Other embodiments]
As mentioned above, although embodiment of this invention was described, this invention can take various forms, 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, implementing 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 antennas, one for selecting n antenna elements from one end of m array antennas and one for selecting n antenna elements from the other end are used. In FIG. 2, although it is set to have a relation of n = m / 2, it is not limited to this, and as shown in FIGS. 6 (a) and 6 (b), 2 ≦ n ≦ m− It can be set arbitrarily within the range of 1. However, as n increases, the positional difference between both partial array antennas decreases, so the resolution of the angle difference degrades, but the number of elements increases, and the number of detectable arrival waves increases. The smaller the difference is, the lower the resolution of the angular difference but the smaller the number of detectable arrival waves.

  Further, the partial array antennas do not necessarily have to be set at both ends, as long as the central 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, and Any two or more can be used.

  (3) In the above embodiment, although the direction of arrival determined using the entire array antenna is the direction of arrival of the direct wave, the direction of arrival determined using the partial array antenna may be used directly as the direction of arrival of the direct wave. 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 reception signal is reacquired for each setting. The signals may be acquired at one time and stored in the memory, and when executing the processing related to the partial array antenna, the stored value of the received signal from the corresponding antenna element may be read out and processed. In this case, since the element switching device 331 can be omitted, the device configuration can be simplified.

  (5) The function possessed by one component in the above embodiment may be distributed to a plurality of components, or the function possessed by 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. In addition, part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above-described embodiment may be added to or replaced with the configuration of the other above-described embodiment. In addition, all the aspects contained in the technical thought specified only by the words described in the claim are an embodiment of the present invention.

  (6) In the present invention, in addition to the arrival direction estimation apparatus (the first receiver 33 and the second receiver 34), an apparatus (measurement apparatus 3) or system (position estimation system 1) having the arrival direction estimation apparatus as a component It can also be realized in various forms.

  DESCRIPTION OF SYMBOLS 1 ... Position estimation system 2 ... Device under test 3 ... Measurement device 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 switching device 332 Receiver 333 Direct wave arrival direction estimation unit

Claims (5)

An arrival direction estimation apparatus (33, 34) for estimating an arrival direction of an incoming wave according to reception signals from m (m is an integer of 3 or more) antenna elements constituting an array antenna (31, 32),
The array antenna is provided for each of a plurality of partial array antennas, each of which is composed of n (1 <n <m) of the antenna elements, and the center positions in the array direction of the antenna elements are different from each other. A first orientation candidate calculation unit (333: S210 to S260) for determining the arrival directions of all incoming waves received according to the reception signal from the partial array antenna;
A direct wave selection unit (333: S270 to S270) that selects direct waves coming directly from the transmission source by comparing the arrival directions of the incoming waves obtained for each of the partial array antennas in the first direction candidate calculation unit. S280),
An arrival direction determination unit (333: S110 to S140, S160) for determining an estimation result of the arrival direction using the arrival direction of the direct wave selected by the direct wave selection unit;
Equipped with
The arrival direction determination unit
A second orientation candidate calculation unit (333: S110 to S140) for estimating the arrival direction of the incoming wave according to the received signals from more antenna elements constituting the partial array antenna;
Selection means (333: selecting the one closest to the arrival direction of the direct wave selected by the direct wave selection unit among the arrival directions calculated by the second orientation candidate calculation unit as the estimation result S160),
An arrival direction estimation apparatus comprising:   The direct wave selection unit determines the angle difference of the arrival direction based on the same arrival wave for each arrival direction detected by any two partial array antennas by the first orientation candidate calculation unit, and the angle difference is the largest. The arrival direction estimation apparatus according to claim 1, wherein the arrival wave that is to be selected is 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 a result of averaging or majority determination of the angle difference for each incoming wave. The arrival direction estimation apparatus according to claim 2. The number m of the antenna element, the maximum number of the reflected wave is assumed as p, any claims 1, characterized according to claim 3 that is set so as to satisfy m ≧ 2 × (p + 1 ) An arrival direction estimation apparatus according to item 1. As the partial array antenna, one using n antenna elements continuous from one end of the array antenna and one 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 4 .

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