Wireless device and method for transmitting common signal

Abstract

To provide a technique for transmitting a common signal from an access point to unspecified terminals without complicating the device configuration.SOLUTION: An array antenna 10 includes a plurality of antenna elements 20 and forms directivity according to a complex amplitude given to each of at least one antenna element 20. A common signal generation unit 40 generates a common signal repeatedly transmitted toward terminals whose locations are unspecified, using the array antenna 10. When transmitting the common signal, a directional antenna control unit 50 sets a set of complex amplitudes given to each of the at least one antenna element 20. The directional antenna control unit 50 has a plurality of sets of complex amplitudes, in each of which with the directivity formed by the array antenna 10 is different from others, and changes the set of complex amplitudes given to each of the at least one antenna element 20 every time the common signal is transmitted at least once.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a wireless device that performs wireless communication with a terminal using a directional antenna, and a method for transmitting a common signal from the wireless device having the directional antenna to a terminal with an unspecified location.

Background Art

[0002] In a cellular wireless communication system and a wireless LAN (Local Area Network), a terminal such as a smartphone or a notebook PC (Personal Computer), or a communication module attached to various sensors and industrial devices, etc. connects to a wireless base station or an access point according to a predetermined standard, and communicates with a terminal and a computer that are communication partners via these. In the following description, a wireless base station in a cellular wireless communication system and an access point in a wireless LAN are collectively referred to as an "access point". Also, a smartphone, a notebook PC, and a communication module are collectively referred to as a "terminal".

[0003] The access point periodically transmits information for each terminal to connect to the access point. The terminal transmits a connection request signal to the access point according to the received information, and performs connection procedures such as authentication with the access point that has received this connection request signal. As a result, the access point and the terminal are in a connected state, and it becomes possible to exchange data with each other.

[0004] In the data exchange after the completion of this connection procedure, if the position of the terminal and the direction in which the terminal exists as seen from the access point are specified, the access point can increase the signal-to-noise power ratio (S / N) and perform high-speed and low-error-rate data communication by using a directional antenna for data transmission to the terminal. At the same time, due to the directional antenna, the radio wave intensity in directions other than the direction in which the terminal exists becomes weak, so that the interference given to the communication of other access points and terminals using the same radio frequency can be reduced. As a result, it can also contribute to the improvement of the communication quality in the other access points and terminals.

[0005] Furthermore, when the access point receives a signal from the terminal, by using a directional antenna, the S / N of the received signal can be increased and the interference received from the communication performed by other access points and terminals can be reduced.

[0006] Thus, for the signal exchanged between the access point and a specific terminal (hereinafter, also referred to as "individual signal"), the S / N can be increased by using a directional antenna, and the interference to other access points and terminals can be reduced.

[0007] On the other hand, for example, for the signal (hereinafter, also referred to as "common signal") transmitted by the access point to unspecified terminals in order to notify each terminal of the information necessary for the terminal to issue a connection request to the access point, the direction in which the terminal receiving this exists is not determined. Therefore, the access point needs to transmit the common signal using a non-directional antenna (omnidirectional antenna), or transmit the common signal using various directivities so as to cover all directions.

[0008] In particular, in cellular wireless communication systems and wireless LANs that utilize millimeter waves indicating radio waves with frequencies in the range of 10 to 100 GHz, sub-terahertz waves exceeding 100 GHz, and terahertz waves ranging from 1 to 10 THz, in order to compensate for large propagation losses, directive antennas with a large number of elements and high directive gain are used (see, for example, Non-Patent Document 1). Since the directivity generated by a directive antenna with high directive gain becomes sharper, when transmitting a common signal using such a directive antenna, in order to cover all directions, more directivities will be used for transmission. According to the standard specifications of NR (New Radio), which is a wireless communication method of the 5th generation mobile communication system (5G), an access point is configured to be able to transmit a common signal with up to 64 different directivities. The access point sequentially switches the directivity at a predetermined transmission interval to transmit the common signal.

Prior Art Documents

Non-Patent Documents

[0009]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, in a configuration where a common signal is transmitted by sequentially switching more directivities, unless the transmission interval of the common signal is shortened, the frequency at which the common signal is sent in a specific direction decreases. When the timing at which the common signal is transmitted toward the terminal's own direction is unknown to the terminal, the terminal has to continue the detection operation of the common signal until the common signal is detected. The time from when the terminal starts the detection operation of the common signal until the common signal is transmitted toward the direction of the terminal is, on average, half of the transmission interval of the common signal, but in the worst case, it can be almost the transmission interval of the common signal.

[0011] On the other hand, when transmitting a common signal using an omnidirectional antenna or a directional antenna with low directivity, the radio wave intensity becomes weaker by the amount of the directivity gain that cannot be obtained. Therefore, it is required to transmit the common signal with a larger transmission power or to transmit the common signal repeatedly a plurality of times. According to this, the terminal can detect the common signal according to the fact that the common signal has been transmitted with a large transmission power or the number of common signals necessary for detection has been transmitted.

[0012] However, equipping an access point with an omnidirectional antenna or a directional antenna with low directivity separately from an array antenna composed of a large number of antenna elements for transmitting a common signal complicates the device configuration of the access point, and as a result, there is a concern that the design cost and device cost of the access point will increase.

[0013] The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide a technique for transmitting a common signal from an access point to unspecified terminals without complicating the device configuration.

Means for Solving the Problems

[0014] A wireless device according to one aspect of the present disclosure includes an array antenna, a common signal generation unit, a directive antenna control unit, a baseband signal generation unit, and a radio unit. The array antenna has a plurality of antenna elements and is configured to form a directivity according to a complex amplitude given for each at least one antenna element. The common signal generation unit generates a common signal that is repeatedly transmitted toward a terminal with an unspecified location using the array antenna. The directive antenna control unit sets a set of complex amplitudes given for each at least one antenna element when transmitting the common signal. The baseband signal generation unit generates a baseband signal supplied for each at least one antenna element from the common signal using the set of set complex amplitudes. The radio unit is provided for each at least one antenna element, converts a corresponding baseband signal into a radio signal, and supplies it to the array antenna. The directive antenna control unit has a plurality of sets of complex amplitudes in which the directivities formed by the array antenna are different from each other, and changes the set of complex amplitudes given for each at least one antenna element every time the common signal is transmitted at least once.

Advantages of the Invention

[0015] According to the present disclosure, in a cellular wireless communication system and a wireless LAN, an access point can form a pseudo-omnidirectional antenna from a directive antenna used for transmitting an individual signal and transmit a common signal toward an unspecified terminal. According to this, the terminal can quickly detect the common signal. In addition, since the access point does not need to be equipped with an omnidirectional antenna for transmitting the common signal, it can contribute to reducing the design cost and the manufacturing cost.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0018] [Embodiment 1] <Configuration of Wireless Device> FIG. 1 is a block diagram showing the functional configuration of a wireless device according to Embodiment 1 of the present disclosure. The wireless device 100 according to Embodiment 1 can be applied to an access point in a cellular wireless communication system and a wireless LAN.

[0019] (Array Antenna 10) As shown in FIG. 1, the wireless device 100 includes an array antenna 10. The array antenna 10 ANT is configured to include N ANT antenna elements 20. N ANT is an integer of 2 or more. The N

[0020] directional gain of the array antenna 10 can be obtained by arranging the N ANT antenna elements 20. For example, if two antenna elements 20 are arranged side by side and fed equally to both, or the received signals of both are combined equally, a directional gain of 3 dB (doubled) can be obtained in a direction perpendicular to the arrangement direction of the two antenna elements 20. Also, the directional gain in other directions is determined by the angle formed with the line on which the two antenna elements 20 are arranged side by side and the interval between the two antenna elements 20. This directional gain can have a maximum value of 3 dB (doubled) and a minimum value of 0. Note that a directional gain of 0 means that no radio wave is radiated in that direction and no radio wave from that direction is received.

[0021] When the number of antenna elements 20 is N ANT , the maximum value of the directional gain is 10 log 10 N ANT dB (N ANT times), and the minimum value is 0. The N ANT antenna elements 20 are not limited to being arranged on a straight line, and can be arranged in various shapes such as on a circle, in a plane, or three-dimensionally. FIG. 2 is a diagram schematically showing a configuration example of the array antenna 10.

[0022] As shown in FIG. 2, the array antenna 10 has N ANTA Uniform Linear Array (ULA) with N antenna elements 20 arranged at equal intervals on a straight line ANT a Uniform Circular Array (UCA) with N antenna elements 20 arranged at equal intervals on a circle, and ANT a Uniform Planar Array (UPA) with N antenna elements 20 arranged in a grid pattern on a plane, etc. are included.

[0023] Here, consider a uniform linear array antenna in which the n-th antenna element 20 is arranged at the position given by Equation (1) on a straight line. n is an integer greater than or equal to 1 and ANT less than or equal to N.

[0024]

Equation

[0025] The directivity gain obtained by this uniform linear array antenna is given by Equation (2).

[0026]

Equation

[0027] where d is the interval between the antenna elements 20 of the uniform linear array, a(n) is the complex amplitude given when feeding the n-th antenna element 20, or the complex amplitude given when synthesizing the received signals of the n-th antenna element 20 at the time of reception. λ is the wavelength of the radio wave, N ANT is the number of antenna elements 20, and θ is the direction in which the radio wave is radiated or received, which is the angle formed with the plane perpendicular to the straight line on which the antenna elements 20 are arranged.

[0028] When the complex amplitudes given to all the antenna elements 20 are equal, directivity occurs in the direction of θ = 0, that is, the direction perpendicular to the straight line on which the antenna elements are arranged. Also, when the complex amplitudes according to Equation (3) are given to all the antenna elements 20, directivity occurs in the direction of θ = θ0.

[0029]

Number

[0030] Equation (2) is the sum of complex amplitudes taking into account the phase difference due to the path difference generated from each antenna element 20 in the direction of θ, and the directivity gain by other shaped array antennas can be calculated in the same way.

[0031] In Embodiment 1, it is assumed that the array antenna 10 is an equally spaced planar array antenna in which N ANT elements (= N ANTx × N ANTy ) of antenna elements 20 are arranged on the x-y plane. N ANTx is the number of antenna elements 20 arranged in the x-axis direction, and N ANTy is the number of antenna elements 20 arranged in the y-axis direction. The position (x, y) of the n-th antenna element 20 on the x-y plane is given by Equations (4) and (5).

[0032]

Number

[0033]

Number

[0034] The directivity gain generated in the direction of the azimuth angle θ and the elevation angle ψ with respect to the x-axis in the x-y plane where the array antenna 10 is arranged is given by Equation (6).

[0035]

Number

[0036] However, a(n x , n y ) is (x, y) = (n x d, n y on the x-y planeIt is the complex amplitude applied to the antenna element 20 located at the position of d). This complex amplitude a(n x ,n y ) is expressed by Equation (7), and maximum directivity occurs in the directions of the azimuth angle θ0 and the elevation angle ψ0.

[0037]

Equation

[0038] When increasing the number of antenna elements 20 of the array antenna 10 to obtain a higher directivity gain, the directivity generated by the array antenna 10 becomes sharper. Therefore, radio waves are radiated more concentratedly in a specific direction. Also, radio waves in a specific direction are received more selectively.

[0039] The wireless device 100 according to Embodiment 1 transmits a common signal to a terminal with an unspecified location using such an array antenna 10 having a high directivity gain. For this, in the scenario where the wireless device 100 transmits a common signal, by applying a complex amplitude with a random phase to each antenna element 20 of the array antenna 10, the array antenna 10 can be made into a pseudo-omnidirectional antenna.

[0040] FIG. 3 is a diagram showing the result of simulating the directivity generated when a complex amplitude with a random phase is applied to each antenna element 20 of an equally spaced planar array antenna.

[0041] As shown in FIG. 3, it can be seen that the pseudo-omnidirectionality generated in the equally spaced planar array antenna is not perfect omnidirectionality, and the strength of radio wave radiation varies depending on the direction. According to this, there is a concern that if the terminal is located in a direction where the radio wave radiation is weak, the terminal may not be able to detect the common signal.

[0042] To address such concerns, the wireless device 100 according to Embodiment 1 is configured to repeatedly transmit a common signal using the array antenna 10. Further, in this configuration, each time at least one common signal is transmitted, the complex amplitude applied to each antenna element 20 of the array antenna 10 is changed.

[0043] In contrast to Embodiment 1, in a configuration where a common signal is repeatedly transmitted with the complex amplitude applied to each antenna element 20 fixed, in the array antenna 10, the imperfect omnidirectionality shown in FIG. 3 is continuously generated.

[0044] On the other hand, in Embodiment 1, by adopting a configuration in which a common signal is repeatedly transmitted while changing the complex amplitude applied to each antenna element 20, it is possible to avoid continuously generating the same pseudo-omnidirectionality at the array antenna 10 when the common signal is repeatedly transmitted. As a result, the imperfection of the pseudo-omnidirectionality is eliminated, and terminals in any direction can receive the common signal.

[0045] FIG. 1 shows the processing blocks related to the transmission of the common signal included in the wireless device 100. Note that processing blocks related to the transmission of wireless signals other than the common signal, processing blocks related to the reception of wireless signals, and processing blocks for exchanging data to be transmitted and received with the outside of the device (or the upper layer of the device) are not directly necessary for explaining this embodiment, so the illustration is omitted. Hereinafter, the processing blocks related to the transmission of the common signal will be described in detail.

[0046] As shown in FIG. 1, the wireless device 100 includes a radio protocol control unit 30, a common signal generation unit 40, a directional antenna control unit 50, a baseband signal generation unit 60, and N ANT wireless units 70. These processing blocks are implemented by hardware such as a CPU (Central Processing Unit) and a memory, and software that performs the arithmetic processing described below.

[0047] (Wireless Protocol Control Unit 30) When it is determined to transmit a common signal, the wireless protocol control unit 30 is configured to instruct the common signal generation unit 40 and the directional antenna control unit 50 of the timing for transmitting the common signal.

[0048] Specifically, the wireless protocol control unit 30 instructs the common signal generation unit 40 of the timing for generating a sequence of data symbols (hereinafter also referred to as "data sequence") A k When giving this instruction, the wireless protocol control unit 30 may also instruct the parameters for determining the data sequence A k and / or the number of times of repeatedly transmitting the common signal.

[0049] (Common Signal Generation Unit 40) At the timing instructed by the wireless protocol control unit 30, the common signal generation unit 40 generates a data sequence A defined as a common signal k and is configured to send the generated data sequence A k to the baseband signal generation unit 60.

[0050] FIG. 4 is a diagram showing an example of the data sequence A generated by the common signal generation unit 40 k As shown in FIG. 4, the data sequence A k can be a sequence obtained by repeating a Zadoff-Chu sequence Z of length La k N REP times. N REP corresponds to the number of times of repeatedly transmitting the common signal. The Zadoff-Chu sequence of length La is given by Equation (8). R is a parameter for determining the Zadoff-Chu sequence. k is an integer from 0 to La - 1.

[0051]

Equation

[0052] The wireless protocol control unit 30 is the data sequence Ak When instructing the timing to generate, La, N REP , at least one of R can be instructed to the common signal generation unit 40. In the case where there is no instruction from the radio protocol control unit 30, the common signal generation unit 40 can set these values to default values that it has in advance.

[0053] Data sequence A k can also be generated by the data sequence generator shown in FIG. 5. As shown in FIG. 5, the data sequence generator includes a shift register in which a plurality (for example, seven) of flip-flops 42 are connected in multiple stages.

[0054] When the generation of the data sequence A k is instructed, the common signal generation unit 40 sets an initial value in each flip-flop 42. Then, by shifting the data in order for each symbol clock, a predetermined sequence consisting of 1 and 0 is generated. In the example of FIG. 5, the data sequence generator is a data sequence generator that generates an M-sequence according to the generating polynomial g(x) shown in Equation (9), and is configured to generate an M-sequence with a period of 127 (= 2 7 -1).

[0055]

Equation

[0056] By shifting the shift register 127 × N REP times, an M-sequence with a length of 127 is repeated N REP times to generate the data sequence A k . Note that by changing the number of flip-flops constituting the shift register, as well as the number and position of adders, different M-sequences corresponding to different generating polynomials can be generated. The radio protocol control unit 30 can specify the generating polynomial used by the data sequence generator and its initial value when instructing the timing to generate the data sequence A k .

[0057] (Baseband signal generation unit 60) The baseband signal generation unit 60 is configured to generate a continuous baseband signal representing the amplitude and phase of the radio signal transmitted from each antenna element 20 of the array antenna 10 corresponding to the data sequence A sent from the common signal generation unit 40. k When the data sequence sent from the common signal generation unit 40 is A

[0058] When the data sequence sent from the common signal generation unit 40 is A k (k = 1, ···, N REP × La), the baseband signal generation unit 60 generates a baseband signal S n (t) corresponding to the radio signal transmitted from the nth antenna element 20 according to Equation (10).

[0059] [Number]

[0060] a k (n) is the complex amplitude given to the nth antenna element 20 when transmitting the kth symbol of the data sequence A k . n is an integer greater than or equal to 1 and less than or equal to N ANT . h(t) is a time - continuous signal waveform for transmitting one symbol in the data sequence A k . A raised cosine waveform given by Equation (11) can be used for h(t).

[0061] [Number]

[0062] T S is the time during which one symbol of the data sequence A k continues. α is a number called the roll - off factor, and a value usually between 0.2 and 0.5 is selected according to the allowable bandwidth of the radio signal, etc.

[0063] FIG. 6 is a diagram schematically showing the time waveform of the baseband signal S n (t). The baseband signal S n (t) is a temporally continuous waveform. However, in an actual device, the value obtained by Equation (10) is sampled at time intervals obtained by dividing one symbol time T S into 4 to 16 parts, and the sampled values are digitally-to-analog converted and output as a waveform smoothed by a low-pass filter.

[0064] (Directional antenna control unit 50) The directional antenna control unit 50 is configured to set the complex amplitude given to each antenna element 20 of the array antenna 10 when transmitting a common signal, and supply the set complex amplitude to the baseband signal generation unit 60.

[0065] In the wireless device 100 according to the first embodiment, the complex amplitude given to each antenna element 20 is a random complex number having a magnitude of 1 and uniformly distributed in the range of a phase angle from 0 to 2π so that directivity is not formed only in a specific direction.

[0066] FIG. 7 is a diagram for explaining the processing in the directional antenna control unit 50. As shown in FIG. 7, the directional antenna control unit 50 prepares a plurality of sets of complex numbers, with the number of complex numbers in one set being the same as the number N ANT of antenna elements 20 constituting the array antenna 10.

[0067] One set of complex numbers includes N ANT random complex numbers having a magnitude of 1 and uniformly distributed in the range of a phase angle from 0 to 2π. In the example of FIG. 7, the number of sets of complex numbers is prepared to be equal to the number of repetitions N REP of the common signal.

[0068] For each repetition of the common signal, the directional antenna control unit 50 selects one set of complex numbers from the N REP sets of complex numbers, and supplies the selected set of complex numbers to the baseband signal generation unit 60 as the complex amplitude a k (n) given to each antenna element 20.

[0069] In the example of FIG. 7, at the first iteration, the first set of complex numbers is selected, and the complex amplitude a k (n) is given to the baseband signal generator 60. Therefore, the data sequence A k The first to Lath symbols A1 to A La and N in the first set of complex numbers ANT and the baseband signal S n (t) is generated.

[0070] At the second iteration, a second set of complex numbers is selected to produce the complex amplitude a k (n) is given to the baseband signal generator 60. Therefore, the data sequence A k Symbols A from La+1th to 2×Lath of La+1 ~A 2×La and N in the second set of complex numbers ANT and the baseband signal S n (t) is generated.

[0071] The number of repetitions is N REP At the time of the Nth REP A set of complex numbers is selected to give the complex amplitude a k (n) is given to the baseband signal generator 60. According to this, the data sequence A k Of which (N REP -1) × La + 1st to Nth REP ×Lath symbol A (NREP-1)×La+1 ~A NREP×La and the Nth REP N in the set of complex numbers ANT and the baseband signal S n (t) is generated.

[0072] In this way, the number of repetitions of the common signal is N REP By preparing the same number of complex number sets as N, it is possible to set complex amplitudes using different complex number sets for repetition of the common signal. REPWhen repeatedly transmitting, the array antenna 10 can generate directivities in N REP ways. Therefore, it is possible to eliminate the non-directionality incompleteness in a pseudo-omnidirectional antenna and suppress the formation of directivity only in a specific direction.

[0073] However, when there is a limit to the number of sets of complex numbers that the directive antenna control unit 50 can prepare, in a part of the number of repetitions N REP of the common signal, a configuration may be adopted in which the set of complex numbers selected in the past is selected again. In a certain aspect, every X repetitions, one set of complex numbers is selected from X sets of complex numbers and supplied to the baseband signal generation unit 60 as the complex amplitude a k (n). However, X is an integer greater than or equal to 2 and less than N REP . In this case, the directive antenna control unit 50 only needs to prepare at least X sets of complex numbers.

[0074] (Radio unit 70) N ANT radio units 70 are provided corresponding to N ANT antenna elements 20 respectively, and are configured to handle the radio signals transmitted by the corresponding antenna elements 20. FIG. 8 is a diagram showing a configuration example of the radio unit 70. As shown in FIG. 8, the radio unit 70 includes a quadrature modulator 72, a frequency converter 74, and an amplifier 76.

[0075] The quadrature modulator 72 quadrature-modulates the baseband signal S n (t) given from the baseband signal generation unit 60 and supplies it to the frequency converter 74. The frequency converter 74 converts the modulation signal given from the quadrature modulator 72 into a high-frequency signal. The amplifier 76 amplifies the high-frequency signal to a level required for transmission and outputs it to the corresponding antenna element 20. The antenna element 20 radiates the amplified high-frequency signal into space as radio waves.

[0076] <Effect> As described above, radio apparatus 100 according to the first embodiment is configured to change the complex amplitude given to each antenna element 20 of array antenna 10 at least every time the common signal is transmitted repeatedly.

[0077] 9 is a diagram showing the results of a simulation of the directivity generated by the array antenna 10 when a common signal is transmitted. In the simulation, a complex amplitude is set to each antenna element 20 using a different set of complex amplitudes for the repetition of the common signal. As described above, one set of complex amplitudes is set to N random amplitudes with a magnitude of 1 and a phase angle uniformly distributed in the range of 0 to 2π. ANT It contains complex numbers.

[0078] 9 shows the directivity when the number of repetitions is 1, the directivity when the number of repetitions is 2, and the directivity when the number of repetitions is 3. It can be seen that by changing the complex amplitude given to each antenna element 20 for each repetition of the common signal, the directivity generated by the array antenna 10 also changes for each repetition.

[0079] Figure 10 shows the number of repetitions of the common signal, N REP 10 is a diagram showing the directional gain of the array antenna 10 with respect to the number of repetitions of the common signal N REP When =1, N REP = 10, and N REP 10 shows the average value of the directional gain of the array antenna 10 when .times. ...

[0080] As shown in Figure 10, the number of repetitions N REP When N = 1, the directivity gain varies in both the azimuth and elevation directions.REP As the number of repetitions N increases, the variation in the directivity gain decreases in both the azimuth and elevation directions. REP When .DELTA.=100, the directional gain is nearly uniform in the azimuth and elevation directions, and as a result, the radiation pattern of radio waves from array antenna 10 is nearly a perfect circle. This makes it possible for terminals in any direction to receive the common signal.

[0081] Therefore, wireless device 100 can transmit a common signal to terminals whose locations are unspecified using array antenna 10. This eliminates the need for wireless device 100 to be equipped with an omnidirectional antenna for transmitting the common signal, which contributes to reducing design and manufacturing costs. Furthermore, terminals can quickly detect the common signal transmitted from wireless device 100.

[0082] [Embodiment 2] In the first embodiment, N ANTx ×N ANTy A configuration has been described in which omnidirectionality is achieved over the range of all azimuth angles and elevation angles by providing each of the antenna elements 20 with a complex amplitude consisting of complex numbers with a magnitude of 1 and a random phase angle.

[0083] In the second embodiment, a configuration is described for transmitting a common signal to unspecified terminals present within a specific range using an equally-spaced planar array antenna configured to have directivity within that range. Note that the configuration of radio device 100 according to the second embodiment is the same as the configuration of radio device 100 according to the first embodiment shown in FIG. 1, except for the configuration of array antenna 10.

[0084] FIG. 11 is a diagram schematically illustrating an example of the configuration of array antenna 10 included in radio device 100 according to the second embodiment. As shown in FIG. 11, array antenna 10 has N ANTx ×N ANTyIt is an equally spaced planar array antenna in which N antenna elements 20 are arranged on the x-y plane. ANTx ×N ANTy The N antenna elements 20 are grouped into a plurality of antenna groups 12 with 2×2 antenna elements 20 as one antenna group 12. Note that the total number of antenna groups 12 included in the array antenna 10 is N ANTx / 2×N ANTy / 2.

[0085] FIG. 12 is a diagram showing a configuration example of the antenna group 12. As shown in FIG. 12, the antenna group 12 includes four antenna elements 20_1 to 20_4, two phase shifters 14 and 16, and a power feeding terminal 18. The power feeding terminal 18 is commonly provided for the four antenna elements 20_1 to 20_4. The power feeding terminal 18 receives a radio signal transmitted from the nth antenna group from the corresponding radio unit 70.

[0086] The phase shifter 14 is provided between the power feeding terminal 18 and the second antenna element 20_2, and gives a phase difference of -90° between the radio signal given to the first antenna element 20_1 and the radio signal given to the second antenna element 20_2.

[0087] The phase shifter 16 is provided between the power feeding terminal 18 and the fourth antenna element 20_4, and gives a phase difference of +90° between the radio signal given to the third antenna element 20_3 and the radio signal given to the fourth antenna element 20_4.

[0088] The four antenna elements 20_1 to 20_4 constituting the antenna group 12 are configured to radiate signals having phase differences of 0°, -90°, 0°, and 90° with respect to the fed radio signal into space.

[0089] FIG. 13 is a diagram schematically showing the directivity generated by the antenna group 12 shown in FIG. 12. As shown in FIG. 13, the antenna group 12 has a wide directivity over the range of azimuth angles 0 to 90° and elevation angles 0 to 90° centered on the directions of azimuth angle 45° and elevation angle 45°.

[0090] The wireless device 100 according to Embodiment 2 has N ANTx / 2 × N ANTy / 2 baseband signal generation units 60 corresponding to each of the N ANTx / 2 × N ANTy / 2 antenna groups 12, N ANTx / 2 × N ANTy / 2 radio units 70, and N ANTx / 2 × N ANTy / 2 radio units 70.

[0091] In the wireless device 100 according to Embodiment 2, the directional antenna control unit 50 gives a complex amplitude with a magnitude of 1 and a random phase to each of the N ANTx / 2 × N ANTy / 2 antenna groups 12. FIG. 14 is a diagram showing the result of simulating the directivity generated when a complex amplitude with a random phase is given to each antenna group 12 of the array antenna 10. As shown in FIG. 14, the array antenna 10 generates pseudo-omnidirectionality within the range of directivity shown in FIG. 13. However, it is not a complete omnidirectionality, and there are differences in the strength of radio wave radiation depending on the direction.

[0092] Therefore, when repeatedly transmitting a common signal, the directional antenna control unit 50 is configured to change the complex amplitude given to each antenna group 12 at least once for each transmission of the common signal. According to this, since the directivity generated by the array antenna 10 changes according to the repetition of the common signal, the incompleteness of omnidirectionality in the pseudo-omnidirectional antenna is eliminated. As a result, omnidirectionality within the range of directivity shown in FIG. 13 can be realized.

[0093] In order to cover the entire half-space by installing the array antenna 10 shown in FIG. 11 on a wall or ceiling, four wireless devices 100 according to Embodiment 2 may be provided.

[0094] In addition, in the second embodiment, the configuration in which a common signal is repeatedly transmitted using the array antenna 10 in which 2×2 antenna elements 20 are grouped as one antenna group 12 has been described. However, by appropriately changing the number of antenna elements 20 constituting one antenna group 12 and the phase difference given to each antenna element 20, omnidirectionality within various directivity ranges can be easily realized.

[0095] [Embodiment 3] In the second embodiment, N ANTx ×N ANTy antenna elements 20 are grouped in groups of 2×2 on hardware, and the wireless device 100 configured to form omnidirectionality within a specific range using an equally spaced planar array antenna having N ANTx / 2×N ANTy / 2 power supply terminals 18 has been described.

[0096] In the third embodiment, a wireless device that can perform the same operation as the wireless device 100 according to the second embodiment using an equally spaced planar array antenna composed of antenna elements 20 that are not grouped in hardware will be described. Note that the configuration of the wireless device 100 according to the third embodiment is the same as the configuration of the wireless device 100 according to the first embodiment shown in FIG. 1 except for the configuration of the directive antenna control unit 50.

[0097] In the wireless device 100 according to the third embodiment, the array antenna 10 is an equally spaced planar array antenna in which N ANTx ×N ANTy antenna elements 20 are grouped in groups of 2×2. However, the point that it has N ANTx ×N ANTy power supply terminals is different from the array antenna 10 according to the second embodiment.

[0098] The baseband signal generation unit 60 generates a baseband signal S ni (t) transmitted from the i-th antenna element 20 of the n-th group of the array antenna 10. The baseband signal S ni(t) is given by equation (12).

[0099]

number

[0100] a included in the right side of equation (12) k (n i ) is generated by the directional antenna control unit 50. FIG. 15 is a diagram for explaining the processing in the directional antenna control unit 50. As shown in FIG. 15, the directional antenna control unit 50 generates the number N of groups included in the array antenna 10. ANTx / 2×N ANTy A set of complex numbers equal in number to / 2 is prepared, and multiple sets of these complex numbers are prepared.

[0101] A set of complex numbers is a set of random N complex numbers with magnitude 1 and phase angles uniformly distributed between 0 and 2π. ANTx / 2×N ANTy In the example of Figure 15, this set of complex numbers is divided into N complex numbers, REP Prepare a number equal to the number of

[0102] The directional antenna control unit 50 calculates N ANTx / 2×N ANTy / The complex amplitude a given to the nth group by selecting one set of complex numbers from the set of two complex numbers. k (n) is set. Note that the complex amplitude a k (n) is the data sequence A k is the random complex amplitude for each group at the k-th symbol of

[0103] Next, the directional antenna control unit 50 calculates the complex amplitude a k From (n), the complex amplitude a given to each of the 2×2 antenna elements 20 constituting the n-th group is k (n i ) to set the

[0104] Specifically, let the complex amplitude applied to the first antenna element 20 in the n-th group be a k (n1), let the complex amplitude applied to the second antenna element 20 be a k (n2), let the complex amplitude applied to the third antenna element 20 be a k (n3), and let the complex amplitude applied to the fourth antenna element 20 be a k (n4). As shown in FIG. 15, the directional antenna control unit 50 sets the complex amplitude a k (n) to the complex amplitudes a k (n1), a k (n3). Further, the directional antenna control unit 50 sets the number obtained by multiplying the complex amplitude a k (n) by the complex number "-j" to the complex amplitude a k (n2), and sets the number obtained by multiplying the complex amplitude a k (n) by the complex number "+j" to the complex amplitude a k (n4). Using the complex amplitude multiplied by this complex number "-j" is equivalent to phase-shifting the radio signal by -90°. Using the complex amplitude multiplied by the complex number "+j" is equivalent to phase-shifting the radio signal by +90°.

[0105] That is, generating baseband signals multiplied by the complex numbers "-j" and "+j" in the baseband signal generation unit 60 is substantially equivalent to performing phase shifts of -90° and 90° when feeding power to the antenna elements 20 of the antenna group 12 shown in FIG. 12. Therefore, also in the wireless device 100 according to Embodiment 3, similar to the wireless device 100 according to Embodiment 2, by grouping the antenna elements 20 and changing the complex numbers multiplied by the complex amplitudes applied to each antenna element 20 within the group, omnidirectionality within various directivity ranges can be realized.

[0106] Also, compared with the wireless device 100 according to Embodiment 2 in which each antenna group 12 has phase shifters 14 and 16 on hardware, in the wireless device 100 according to Embodiment 3, grouping and phase control of the antenna elements 20 can be performed by arithmetic processing in the baseband signal generation unit 60 and the directive antenna control unit 50, so that various directivities can be formed more easily.

[0107] Within the scope of the present disclosure, it is possible to combine each embodiment, or to appropriately modify or omit each embodiment. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of a plurality of disclosed constituent elements.

[0108] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The technical scope shown by the present disclosure is indicated by the claims rather than the description of the above embodiments, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0109] 10 Array antenna, 12 Antenna group, 14, 16 Phase shifter, 18 Feeding terminal, 20 Antenna element, 30 Wireless protocol control unit, 40 Common signal generation unit, 50 Directive antenna control unit, 60 Baseband signal generation unit, 70 Wireless unit, 72 Quadrature modulator, 74 Frequency converter, 76 Amplifier, 100 Wireless device.

Claims

1. An array antenna having a plurality of antenna elements and configured to form a directivity according to a complex amplitude given to each at least one antenna element; A common signal generation unit that generates a common signal that is repeatedly transmitted toward a terminal whose existence position is unspecified using the array antenna; A directivity antenna control unit that sets a set of complex amplitudes to be given to each at least one antenna element when transmitting the common signal; A baseband signal generation unit that generates a baseband signal to be supplied to each at least one antenna element from the common signal using the set of complex amplitudes that has been set; A radio unit provided for each at least one antenna element, converting the corresponding baseband signal into a radio signal and supplying the radio signal to the array antenna, and The directivity antenna control unit has a plurality of sets of complex amplitudes having different directivities formed by the array antenna, and changes the set of complex amplitudes to be given to each at least one antenna element every time the common signal is transmitted at least once. A wireless device.

2. The wireless device according to claim 1, wherein each of the plurality of complex amplitudes constituting the set of complex amplitudes is a complex number having a magnitude of 1 and a phase following a uniform distribution.

3. Each of the at least one antenna element constitutes a group having two or more antenna elements, and the group has at least one phase shifter configured to give a phase difference between radio signals given to each of the two or more antenna elements. And The wireless device according to claim 1 or 2, wherein the directivity antenna control unit changes the set of complex amplitudes given to each group every time the common signal is transmitted at least once.

4. Each of the at least one antenna element constitutes a group having two or more antenna elements, The directivity antenna control unit Every time the common signal is transmitted at least once, while changing the set of complex amplitudes given to each group, The wireless device according to claim 1 or 2, wherein the complex amplitude to be given to each of the two or more antenna elements is set by multiplying the complex amplitude given to each group by a complex number.

5. A method of transmitting a common signal toward a terminal with an unspecified location using an array antenna, wherein the array antenna has a plurality of antenna elements and is configured to form a directivity according to a complex amplitude given for each at least one antenna element. Generating a common signal repeatedly transmitted toward the unspecified terminal. When transmitting the common signal, setting a set of complex amplitudes to be given for each at least one antenna element. Based on the set of complex amplitudes thus set, generating a baseband signal to be supplied to each at least one antenna element from the common signal. For each at least one antenna element, converting the corresponding baseband signal into a radio signal and supplying it to the array antenna. The step of setting the set of complex amplitudes includes having a plurality of sets of complex amplitudes with different directivities formed by the array antenna, and changing the set of complex amplitudes to be given for each at least one antenna element each time the common signal is transmitted at least once. A method for transmitting a common signal.

6. The method for transmitting a common signal according to claim 5, wherein each of the plurality of complex amplitudes constituting the set of complex amplitudes is a complex number having a magnitude of 1 and a phase following a uniform distribution.

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