Wireless communication device, wireless communication system, calibration method, and calibration program

Abstract

To simply allow a calibration for a short time.SOLUTION: A control part 204 of a radio communication device 110 sets a predetermined delay amount τ to a transmission signal transmitted via each antenna 111, applies each transmission signal to a reference antenna 111a and a calibration object antenna 111b, respectively, the reference antenna being one of the plurality of antennas 111 while the calibration object antenna being another of the plurality of antennas, transmitting the transmission signal from a reference antenna 111a, and controls a transmission of the transmission signal to which the predetermined delay amount τ is applied from the calibration object antenna 111b. The control part 204 sets a phase amount for cancelling a deviation Δ to a phase shifter 114 on the basis of the deviation Δ to a center frequency of a signal provided to a peak value of a power of a reception signal observed on a reception device 150 side by the transmission of the transmission signal.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a wireless communication device, a wireless communication system, a calibration method, and a calibration program.

Background Art

[0002] In order to realize wireless communication in a high frequency band and improve transmission characteristics, beamforming using a plurality of antenna elements is performed. In order to direct the peak of the beam in a desired direction in beamforming, it is necessary to synthesize the radio waves of the plurality of antenna elements so that the phases are in phase in the directed direction.

[0003] A wireless communication device has each antenna element, a distribution circuit, a power amplifier, etc., and variations occur in amplitude and phase in these. In order to correct this variation, it is necessary to calibrate the antenna element.

[0004] As prior art of calibration, for example, there is a technique of dividing a frequency band into a plurality of spectra, transmitting sub-spectra from each antenna, and adjusting so that the amplitude phases of the received sub-spectra through the antenna are aligned with each other. Also, there is a technique of distributing a reference signal, switching and transmitting a plurality of antenna elements, sequentially receiving the transmission signals of each antenna element to obtain power and phase, obtaining the phase difference of each antenna element with respect to the reference phase of one antenna element for each antenna element, and calibrating the phase of each antenna element so as to fall within the tolerance. Also, there is a technique of allocating each sub-carrier of a calibration signal to each antenna element, transmitting from each antenna element, receiving, by a receiving antenna, a received signal in which the calibration signals of each element are superimposed, separating into sub-carriers, and detecting and calibrating the amplitude phase error of each element of a transmitting array antenna. Also, there is a technique called the REV method, in which all elements of the antenna are turned on and measured while sequentially changing the set phase of the measured element, and calibration is performed by measuring only power in the far field by obtaining the relative amplitude and phase difference of the measured element with respect to the synthesized vector in the initial state.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Document

[0006]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the prior art, the calibration of a plurality of antenna elements was time-consuming and laborious. In the conventional calibration, the phase of the phase shifter of each antenna element is changed and the change in received power is monitored to obtain the optimal calibration phase, so it takes time corresponding to the number of set phases. For example, when an N-bit phase shifter is used, 2 N rounds of adjustment processing are required.

[0008] On one aspect, an object of the present invention is to enable calibration simply and in a short time.

Means for Solving the Problems

[0009] According to one aspect of the present invention, in a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas, a delay unit that imparts a predetermined delay amount to a transmission signal transmitted via the antenna, a phase shifter that can variably control the phase of the transmission signal transmitted via the antenna, and a control unit that performs calibration control, wherein the control unit designates one of the plurality of antennas as a reference antenna and another one as an antenna to be calibrated, gives transmission signals to each of them, controls to transmit the transmission signal from the reference antenna and transmit the transmission signal to which the predetermined delay amount is imparted from the antenna to be calibrated, and sets, based on a deviation of the peak value of the power of the received signal, which is observed on the receiving device side due to the transmission of the transmission signal, from the center frequency of the signal, a phase amount for eliminating the deviation, to the phase shifter.

Effect of the Invention

[0010] According to one embodiment of the present invention, there is an effect that calibration can be performed simply and in a short time.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0012] Hereinafter, with reference to the drawings, embodiments of the disclosed wireless communication device, wireless communication system, calibration method, and calibration program will be described in detail.

[0013] (Calibration Example According to the Embodiment) FIG. 1 is an explanatory diagram of an example of the calibration method according to the embodiment. As shown in FIG. 1(a), the wireless communication system 100 includes a transmission device 110 that transmits a transmission signal of a symbol by an IQ digital modulation method such as QPSK or 16QAM, and a reception device 150. The calibration method of the embodiment calibrates a plurality of antenna elements included in the transmission device 110.

[0014] Note that calibration means not only calibrating the antenna elements, but also calibrating variations in the amplitude and phase of a plurality of antenna signals transmitted by the wireless communication device based on variations in each part such as the antenna elements, distribution circuits, and power amplifiers.

[0015] The transmission device 110 is, for example, a base station device, and the reception device 150 is a terminal device capable of wireless communication with the transmission device 110. During calibration, the terminal device is arranged at a fixed position.

[0016] The transmission device 110 has a plurality of antenna elements 111 as transmission antennas for transmitting transmission signals. In the embodiment, the transmission device 110 divides the plurality of antenna elements 111 into a reference antenna 111a and a calibration antenna 111b. The transmission device 110 transmits transmission signals from the reference antenna 111a and the calibration antenna 111b, respectively. The transmission signal has an amplitude and a phase component.

[0017] The receiving device 150 receives the signal transmitted from the transmitting device 110 by the receiving antenna 151 and demodulates the received signal. Also, although details will be described later, the received signal received by the receiving antenna 151 measures the received power for each frequency by a spectrum monitor or the like. The receiving device 150 feedback-outputs the information on the received power for each measured frequency to the transmitting device 110.

[0018] The transmitting device 110 performs calibration of the calibration antenna 111b with reference to the reference antenna 111a. In the example of Fig. 1(a), for convenience, only one of the plurality of calibration antennas 111b for which calibration is performed is shown.

[0019] On the calibration antenna 111b side, a phase shifter 114 and a delay device 115 are provided. The phase shifter 114 varies the phase of the transmission signal. The delay device 115 gives a predetermined delay amount τ to the transmission signal.

[0020] The receiving device 150 receives the signal transmitted from the transmitting device 110 by the receiving antenna 151 and demodulates the received signal. Also, although details will be described later, the received signal received by the receiving antenna 151 measures the received power for each frequency by a spectrum monitor or the like. The receiving device 150 feedback-outputs the information on the received power for each measured frequency to the transmitting device 110.

[0021] Fig. 1(b) is a diagram showing the constellation of signal points on the IQ coordinates when the delay amount τ = 0. The horizontal axis is the I signal and the vertical axis is the Q signal component. As shown in Fig. 1(b), when the delay amount τ of the delay device 115 is 0, the phase of the signal point of the transmission signal of the reference antenna 111a is θ1, and the phase of the signal point of the transmission signal of the calibration antenna 111b is θ2, and it is assumed that there is a variation in phase. In this case, the phase difference θ 21 = θ2 - θ1. For example, in the phase adjustment (equivalent to the prior art) using the phase shifter 114, the phase adjustment amount φ2 of the phase shifter 114 = -θ 21By doing so, the phase θ2 of the calibration antenna 111b can be adjusted to match the phase θ1 of the reference antenna 111a.

[0022] FIG. 1(c) is a diagram showing the received power when the delay amount τ = 0. The horizontal axis represents the frequency f, and the vertical axis represents the received power by the receiving device 150. Assume that the phase adjustment amount φ2 of the phase shifter 114 is changed when the delay amount τ = 0. Since the transmission signal includes an amplitude and a phase component, the received power of the entire signal component increases or decreases according to the change in the phase adjustment amount φ2. In this case, when adjusting the phase only with the phase shifter 114 equivalent to the prior art, it is necessary to find the phase adjustment amount φ2 at which the received power peaks.

[0023] FIG. 1(d) is an IQ characteristic diagram of the transmission signal when the delay amount τ = 1. In the embodiment, during calibration, a delay amount τ is given to the transmission signal on the calibration antenna 111b side by the delay device 115. The delay amount τ is, for example, one sample (Ts: symbol period) of the baseband signal. In this case, since the reference antenna 111a side has a delay amount τ = 0, the phase of the reference antenna 111a remains θ1. On the other hand, the phase θ2 on the calibration antenna 111b side causes the signal point to rotate to the f + or f - side due to the delay amount τ.

[0024] FIG. 1(e) is a diagram showing the received power when the delay amount τ = 1. It shows a characteristic diagram of the received signal transmitted from the reference antenna 111a and the calibration antenna 111b and received by the receiving device 150. By giving a delay amount τ to the transmission signal on the calibration antenna 111b side, a periodic waveform with the characteristic that the received power increases in the part where the signals strengthen each other and decreases in the part where they weaken each other is observed in the signal frequency band. Here, with respect to the center frequency 0 (f0) of the signal observed by the receiving device 150, the peak of the waveform has a frequency shift (deviation) Δ (in the example of FIG. 1(e), +Δ). Therefore, calibration is performed in one observation by giving the phase amount -Δ opposite to the deviation +Δ to the phase shifter 114 of the transmission device 110.

[0025] According to this, according to the embodiment, the calibration of the wireless communication device can be performed simply and in a short time.

[0026] (Configuration example of wireless communication system) FIG. 2 is a diagram showing a configuration example of a wireless communication system. The transmission device 110 of the wireless communication system 100 is, for example, a base station device, and the reception device 150 can use a terminal device capable of wireless communication.

[0027] The transmission device 110 includes a reference antenna 111a shown in FIG. 1, a plurality of calibration antennas 111b, a phase shifter 114, a delay device 115, a transmission signal generation unit 201, a distribution circuit 202, a switch 203, and a control unit 204.

[0028] The transmission device 110 uses one of the plurality of antenna elements 111 as a reference antenna (#0) 111a, and uses the other plurality of antenna elements 111 as calibration antennas (#1 to #N) 111b.

[0029] The transmission signal generation unit 201 outputs the digital transmission signal generated by the transmission device 110 to the antenna element 111. The transmission signal output by the transmission signal generation unit 201 is branched into two, one is output to the system of the reference antenna 111a, and the other is output to the system on the calibration antenna 111b side. Note that the transmission signals input to the reference antenna and the antenna to be calibrated do not have to be the branched output transmission signals, and the same transmission signal may be used.

[0030] A delay device 115, a distribution circuit 202, a phase shifter 114, and a switch 203 are provided in each of the plurality of antenna systems on the calibration antenna 111b side. The delay device 115 gives a delay amount τ to the transmission signal of the system on the calibration antenna 111b side. The distribution circuit 202 distributes the transmission signal to the N calibration antennas 111b.

[0031] The phase shifter 114 varies the phase in each line of the N calibration antennas 111b distributed by the distribution circuit 202. The switch 203 selects one of the calibration antennas (#1 to #N) 111b for calibration according to the selection of the control unit 204. The switch 203 transmits a transmission signal from the selected one calibration antenna 111b.

[0032] The control unit 204 overall controls the transmission device 110 and performs control related to calibration in the embodiment. The control unit 204 shown in FIG. 2 performs control related to calibration based on the information on the frequency spectrum of the received signal acquired from the receiving device 150.

[0033] As control related to calibration, the control unit 204 performs each control of setting the delay amount τ for the delay device 115, selecting the line for calibration by the switch 203, and adjusting the phase for the line for calibration by the phase shifter 114.

[0034] The receiving device 150 includes a receiving antenna 151, a received signal demodulation unit 211, and a frequency spectrum monitor unit 212. The receiving antenna 151 receives the transmission signal transmitted by the transmission device 110. The received signal demodulation unit 211 demodulates the transmission signal received by the receiving antenna 151 and outputs it to a data processing unit such as a decoding unit inside the receiving device 150.

[0035] The received signal of the receiving antenna 151 is branched and output to the frequency spectrum monitor unit 212. The frequency spectrum monitor unit 212 analyzes the frequency spectrum of the received signal and transmits and outputs the analyzed spectrum information to the control unit 204 of the transmission device 110.

[0036] In the system configuration example of FIG. 2, the feedback path of the spectrum information from the receiving device 150 to the transmitting device 110 is not limited to using a communication line. For example, at the time of inspection during shipment, based on the spectrum information of the receiving device 150 in a measurement room, the control unit 204 of the transmitting device 110 can also be calibrated by manually operating the setting of the delay amount and phase.

[0037] (Hardware Configuration Example of Control Unit) FIG. 3 is a diagram showing a hardware configuration example of the control unit. The control unit 204 of the transmitting device 110 includes a processor 301 such as a CPU (Central Processing Unit) shown in FIG. 3, a memory 302, a network IF 303, a recording medium IF 304, and a recording medium 305. Also, each component is connected by a bus 300.

[0038] Here, the processor 301 controls the calibration control according to the embodiment. The processor 301 may have a plurality of cores. The memory 302 has, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash ROM. Specifically, for example, the flash ROM stores a control program, the ROM stores an application program, and the RAM is used as a work area for the processor 301. The program stored in the memory 302 is loaded into the processor 301 to cause the processor 301 to execute the coded process.

[0039] The network IF 303 is connected to the network NW through a communication line and is connected to other communication devices via the network NW. The other communication device is, for example, the receiving device 150 shown in FIG. 1. And the network IF 303 serves as an interface between the network NW and the inside of the device and controls the input / output of data from other communication devices.

[0040] The recording medium IF304 controls the read / write of data to / from the recording medium 305 according to the control of the processor 301. The recording medium 305 stores the data written under the control of the recording medium IF304.

[0041] Also, regarding the receiving device 150, the configuration related to the calibration control can be configured by the hardware shown in FIG. 3.

[0042] (Outline of Calibration Processing) FIG. 4 is an explanatory diagram of the outline of the calibration processing according to the embodiment. The control unit 204 of the transmitting device 110 shown in FIG. 2 performs the calibration processing shown in FIGS. 4(a) to (d). FIGS. 4(a) to (d) are the frequency spectra monitored by the frequency spectrum monitor unit 212 of the receiving device 150, where the horizontal axis is the frequency of the received signal and the vertical axis is the power of the received signal.

[0043] First, the transmitting device 110 (control unit 204) sets the delay amount τ of the delay device 115 to τ = 0 (no delay). The transmitting device 110 selects one of the plurality of calibration antennas 111b. Then, the transmitting device 110 transmits the transmission signal from the reference antenna 111a and the selected calibration antenna 111b. The receiving device 150 receives the transmission signals transmitted from the reference antenna 111a and the selected calibration antenna 111b, and thus, in the receiving device 150, the spectra shown in FIGS. 4(a) to (d) are detected.

[0044] When there is no delay in the transmission signal (τ = 0), the frequency spectrum monitor unit 212 of the receiving device 150 detects a flat received power for the entire signal component according to the phase deviation of the calibration antenna (#1) 111b.

[0045] Figs. 4(a) to 4(d) show the spectra of two calibration antennas (#1, #N) observed at different times for convenience. Note that the received powers of the calibration antennas (#1, #N) 111b shown in Fig. 4(a) are all insufficient due to deviations and show a state of low received power.

[0046] Next, the transmission device 110 sets the delay amount of the delay device 115 to, for example, 2Ts (with delay). Then, the transmission device 110 transmits the transmission signal from the reference antenna 111a and the calibration antennas (#1, #N) 111b, respectively.

[0047] When there is a delay in the transmission signal (τ = 2Ts), as shown in Fig. 4(b), a deviation (-Δ) is observed at the peak of the periodic waveform for the calibration antenna (#1) 111b in the frequency spectrum monitor unit 212 of the reception device 150. Based on this observation, the transmission device 110 gives a phase correction amount +Δ for the calibration antenna (#1) 111b to the phase shifter 114.

[0048] For the calibration antenna (#N) 111b, when there is a delay in the transmission signal (τ = 2Ts), a deviation (+Δ) is observed at the peak of the periodic waveform for the calibration antenna (#N) 111b in the frequency spectrum monitor unit 212 of the reception device 150. Based on this observation, the transmission device 110 gives a phase correction amount -Δ for the calibration antenna (#N) 111b to the phase shifter 114. Here, the deviation (+Δ) and its phase correction amount -Δ are independent and different values for each calibration antenna (#1 to #N).

[0049] As a result, as shown in Fig. 4(c), in the frequency spectrum monitor unit 212 of the reception device 150, the peak of the periodic waveform is located at the center frequency 0 of the transmission signal for the calibration antenna (#1) 111b, and the deviation is eliminated.

[0050] Similarly, for the calibration antenna (#N) 111b as well, in the frequency spectrum monitor section 212 of the receiving apparatus 150, the peak of the periodic waveform is located at the center frequency 0 of the transmission signal, and the deviation is eliminated.

[0051] After calibration, the transmission apparatus 110 returns the delay amount of the delay unit 115 and sets it to no delay (τ = 0). As a result, as shown in FIG. 4(d), the received power of the calibration antenna (#1) 111b reaches a state where sufficient received power can be obtained compared to FIG. 4(a) due to the elimination of the deviation.

[0052] Similarly, for the calibration antenna (#N) 111b as well, the received power reaches a state where sufficient received power can be obtained compared to FIG. 4(a) due to the elimination of the deviation.

[0053] (Specific Example of Calibration Processing of Base Station Apparatus) FIG. 5 is a diagram showing a specific example of the calibration processing of the base station apparatus. The calibration in the transmission apparatus 110 described above can be implemented for an existing base station apparatus.

[0054] The base station apparatus corresponding to the transmission apparatus 110 includes a plurality (#1 to #N) of transmission signal generation sections (digital signal generation sections) 201 for each sector, site, and MIMO transmission. Further, N delay units (digital delays) 115 and N antenna branches 111A, 111B,... 111N are provided. Each antenna branch 111A, 111B,... 111N performs transmission by beamforming using array-shaped antenna elements. Therefore, high-gain calibration is required in the base station apparatus. Note that in FIG. 5, for the sake of convenience, a configuration with N (corresponding to the number of branches) = 2 is shown.

[0055] Also, in the base station apparatus, the delay unit (digital delay) 115 compensates for the delay in signal transmission between the antenna branches 111A, 111B,... 111N.

[0056] In the embodiment, calibration is performed for different antenna branches 111A, 111B, … 111N of the base station apparatus. For example, one antenna element (#6) of the antenna branch 111A is used as the reference antenna 111a. Then, calibration is sequentially performed for each antenna element (#1 to #6) of the antenna branch 111B other than the antenna branch 111A used as the reference antenna 111a, with the antenna element serving as the calibration antenna 111b.

[0057] During this calibration, the delay unit 115 connected to the antenna branch 111B on the calibration side sets the delay amounts τ = 0, 1 respectively.

[0058] As shown in FIG. 5, the base station apparatus has N transmission signal generation units 201. However, in the calibration in the embodiment, as shown in FIG. 2, only one transmission signal generation unit 201 needs to be used. For example, during the calibration of the base station apparatus in FIG. 5, the transmission signal generated by one transmission signal generation unit 201 is branched. Then, one of the transmission signals is output to the antenna branch 111A of the reference antenna 111a, and the other transmission signal is output to the antenna branch 111B of the calibration antenna 111b.

[0059] As described above, in the embodiment, the calibration of the base station apparatus which is the transmission apparatus 110 can be performed using the facilities of the existing base station apparatus.

[0060] (Calibration Processing Example 1) FIG. 6 is a flowchart of a calibration process example. FIG. 6 shows a calibration process corresponding to the configuration example shown in FIG. 2 and is performed by the control unit 204 (processor 301) of the transmission device 110. The calibration process can be performed, for example, when inspecting the transmission device 110 before shipment by arranging the transmission device 110 and the reception device 150 in a measurement room. Further, the calibration process can also be performed at predetermined intervals corresponding to aging changes after shipment. The transmission device 110 transmits the transmission signal from the reference antenna 111a and the calibration antenna 111b by output branching of the transmission signal generation unit 201.

[0061] First, the transmission device 110 transmits a signal (reference signal) from the reference antenna 111a. At this time, the transmission device 110 sets a delay amount τ in the delay unit 115 on the calibration antenna 111b side (step S601). The transmission signal transmitted from the reference antenna 111a serves as a reference for calibrating the calibration antenna 111b.

[0062] Next, the transmission device 110 turns on the switch 203 of the antenna to be calibrated among the calibration antennas 111b that transmit the transmission signal and turns off the other antennas (step S602). For example, the transmission device 110 selects the calibration antennas 111b one by one in a predetermined order #1 to #N. In this way, the transmission device 110 simultaneously transmits the transmission signal output by the transmission signal generation unit 201 from the reference antenna 111a and one calibration antenna 111b of the selected calibration target.

[0063] Next, the transmission device 110 causes the reception device 150 to detect the phase of the transmission-side phase shifter 114 at which the power peaks at the center frequency of the band (step S603). Next, the transmission device 110 sets the phase of the phase shifter 114 at which the power peaks at the center frequency of the band (step S604). The phase detection in step S603 is detected by the frequency spectrum monitor unit 212 of the reception device 150 corresponding to the phase variability of the phase shifter 114 of the transmission device 110 and output to the control unit 204 of the transmission device 110. In step S604, the transmission device 110 (control unit 204) sets the phase of the phase shifter 114 when the power peaks at the center frequency of the band to the phase shifter 114.

[0064] Next, the transmission device 110 determines whether or not calibration has been completed for all the calibration antennas 111b (step S605). As a result of the determination, if there is an antenna (#2 to #N) for which calibration has not been performed (step S605: No), the transmission device 110 returns to the process of step S602. On the other hand, as a result of the determination, if calibration has been completed for all the calibration antennas (#1 to #N) 111b (step S605: Yes), the transmission device 110 proceeds to the process of step S606.

[0065] In step S606, the transmission device 110 returns the delay amount τ set in the delay device 115 in step S601 to 0 (step S606) and ends the above processing.

[0066] In the calibration process shown in FIG. 6, calibration for one selected calibration antenna 111b can be quickly performed by executing the phase detection and setting processes of steps S603 and S604 only once. In contrast, in the prior art, the above-described two N rounds of adjustment processing are required in the phase adjustment processing corresponding to steps S603 and S604 of FIG. 6, which is complicated.

[0067] (Another configuration example of the wireless communication system) FIG. 7 is a diagram showing another configuration example of a wireless communication system. In the wireless communication system 100 shown in FIG. 7, the transmitter 110 has the same configuration as that in FIG. 2, so the description thereof is omitted. The receiver 150 shown in FIG. 7 is configured more simply than that in FIG. 2.

[0068] The receiver 150 includes a receiving antenna 151, a received signal demodulation unit 211, a plurality of band filters 701, a received power measurement and maximum power frequency estimation unit 702, a transmitter-side optimal phase calculation unit 703, and a set phase feedback unit 705. The receiving antenna 151 receives the transmission signal transmitted by the transmitter 110. The received signal demodulation unit 211 demodulates the transmission signal received by the receiving antenna 151 and outputs it to a data processing unit such as a decoding unit inside the receiver 150.

[0069] The received signal of the receiving antenna 151 is branched and output to a plurality of band filters 701. The plurality of band filters 701 can be composed of a plurality of band-pass filters (BPFs) that pass the frequency band of the received signal through different frequency bands. For example, the band filter 701 may be arranged for each specific sub-band (e.g., 10) of OFDM (Orthogonal Frequency Division Multiplexing).

[0070] The received power measurement and maximum power frequency estimation unit 702 measures the received power of the received signal after passing through the band filter 701. The received power measurement and maximum power frequency estimation unit 702 estimates the maximum power of the received power that has passed through each band filter 701 by this measurement.

[0071] The transmitter-side optimal phase calculation unit 703 calculates the optimal phase in the transmitter 110 corresponding to the maximum power of the received power estimated by the received power measurement and maximum power frequency estimation unit 702.

[0072] The set phase feedback unit 705 feedback-outputs the phase calculated by the transmitter-side optimal phase calculation unit 703 to the transmitter 110.

[0073] In the system configuration example of FIG. 7, the phase required for calibration can be detected with a simple configuration. For example, in the configuration example of FIG. 7, it is not necessary to arrange the frequency spectrum monitor unit 212 arranged on the receiving device 150 side of FIG. 2, and the function similar to the frequency spectrum monitor unit 212 can be simplified.

[0074] In the system configuration example of FIG. 7, a transmission-side optimum phase calculation unit 703 is provided in the receiving device 150, and the result is sent from the set phase feedback unit 705 to the transmission side. Not limited to this, the result of the received power measurement / maximum power frequency estimation unit 702 may be fed back to the transmission side, and the control unit 204 of the transmission device 110 may perform a process corresponding to the transmission-side optimum phase calculation unit 703 to obtain the set phase.

[0075] Also, in the system configuration example of FIG. 7, the phase information fed back from the receiving device 150 to the transmitting device 110 is not limited to being transmitted using a communication line. For example, in a measurement room where inspection at the time of shipment is performed, based on the phase information detected on the receiving device 150 side, an operator can manually operate the phase setting for calibration of the control unit 204 of the transmitting device 110.

[0076] (Calibration processing example 2) FIG. 8 is a flowchart of another calibration processing example. FIG. 8 is a calibration process corresponding to the configuration example shown in FIG. 7, and is performed by the control unit 204 (processor 301) of the transmission device 110.

[0077] First, the transmission device 110 transmits a signal (reference signal) from the reference antenna 111a and sets a delay amount τ in the delay device 115 on the calibration antenna 111b side (step S801).

[0078] Next, the transmission device 110 turns on the switch 203 of the antenna for which calibration is to be performed among the calibration antennas 111b, and turns off the other antennas (step S802). For example, the transmission device 110 selects the calibration antennas 111b one by one in a predetermined order #1 to #N.

[0079] Next, the transmission device 110 measures the power of each band with the band filter 701 of the reception device 150, and detects the phase of the phase shifter 114 at which the power peaks at the center frequency of each band (step S803). Next, the transmission device 110 sets the phase of the phase shifter 114 at which the power peaks at the center frequency of the band (step S804). The detection of the phase in step S803 is calculated by the transmission-side optimum phase calculation unit 703 of the reception device 150 corresponding to the phase variability of the phase shifter 114 of the transmission device 110, and is output to the control unit 204 of the transmission device 110. In step S604, the transmission device 110 (control unit 204) sets the phase of the phase shifter 114 when the power peaks at the center frequency of the band in the phase shifter 114.

[0080] Next, the transmission device 110 determines whether or not calibration has been performed for all the calibration antennas 111b (step S805). As a result of the determination, if there are antennas for which calibration has not been performed (#2 to #N) (step S805: No), the transmission device 110 returns to the process of step S802. On the other hand, as a result of the determination, if calibration has been performed for all the calibration antennas (#1 to #N) 111b (step S805: Yes), the transmission device 110 proceeds to the process of step S806.

[0081] In step S806, the transmission device 110 returns the delay amount τ set in the delay device 115 in step S801 to 0 (step S806), and ends the above process.

[0082] (Calibration Process Example 3) FIG. 9 is a diagram showing another configuration example of a wireless communication system. In a wireless communication system including a base station device (transmission device) 110 and a wireless relay device 900 shown in FIG. 9, calibration of the transmission device 110 can also be performed.

[0083] The wireless relay device 900 includes a reception antenna 901, a wireless relay processing unit 902, and a transmission antenna 903. Then, the reception signal received by the reception antenna 901 is branched, one is output to the wireless relay processing unit 902, and the other is output to a frequency spectrum monitor unit 212 (see FIG. 2 etc.).

[0084] The frequency spectrum observed by the frequency spectrum monitor unit 212 is output to the control unit 204 of the transmission device 110. Here, the installation position of the frequency spectrum monitor unit 212 may be installed at the local site where the wireless relay device 900 is installed, or may be installed at a remote site remotely connected to the wireless relay device 900.

[0085] With the above configuration, calibration of the transmission device 110 can be performed using the wireless relay device 900.

[0086] Furthermore, since the wireless relay device 900 itself has a plurality of antenna elements 111 and has each component (transmission signal generation unit 201 to switch 203) of the transmission device 110 shown in FIG. 9, calibration of the wireless relay device 900 itself can also be performed.

[0087] The wireless communication device according to the embodiment described above is a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas. Among the plurality of antennas, one is a reference antenna, and the other plurality of antennas are calibration antennas. The transmission signal is branched and output to each of them. In each antenna system on the calibration antenna side, there are a delay unit that imparts a predetermined delay amount to the transmission signal, a switch that selects one of the plurality of calibration antennas as the antenna to be calibrated, and a phase shifter that can freely vary the phase of the transmission signal of the selected antenna to be calibrated. The control unit that performs calibration control sets a predetermined delay amount for the transmission signal of the calibration antenna, selects one antenna to be calibrated, and when transmitting the transmission signal from the antenna to be calibrated, based on the deviation of the peak value of the power of the received signal observed on the receiving device side with respect to the center frequency of the signal, sets the phase amount that eliminates the deviation in the phase shifter. In addition, the control unit sets the phase amount that eliminates the deviation for each of the plurality of calibration antennas. After sequentially performing calibration, the set delay amount is restored. In this way, in the embodiment, by setting a delay between the reference antenna and the calibration antenna during calibration, the transmission signal is given frequency characteristics, and the phase deviation component can be easily detected from the received signal. Note that not only the control by the control unit is limited, but based on the deviation observed by the receiving device, the phase amount that eliminates the deviation may be directly set in the phase shifter by an operator. Thereby, according to the wireless communication device, a plurality of antennas can be calibrated easily and in a short time.

[0088] The wireless communication device also has a plurality of antenna branches each consisting of a plurality of antennas. The control unit selects one antenna of one antenna branch among the plurality of antenna branches as a reference antenna, and sequentially selects a plurality of antennas of other antenna branches among the plurality of antenna branches as antennas to be calibrated. This enables calibration of the plurality of antennas included in the antenna branches while using, as is, the existing configuration of, for example, a base station device which is a wireless communication device.

[0089] Note that in the above-described embodiment, a consistent description has been given assuming a configuration in which "a switch is provided on the calibration antenna side, the switch of the antenna to be calibrated is turned ON, the switches of the other antennas are turned OFF, and calibration of the antenna is performed". However, this is not the only way. As a method equivalent to turning the switch of the antenna to be calibrated ON or OFF, calibration may be performed by turning the gain of the transmission amplifier to the normally used state (switch ON) and turning the gain of the transmission amplifier to the lowered state (switch OFF). A method using such gain adjustment of the transmission amplifier can be similarly applied to the following configurations.

[0090] In addition, a wireless communication system can be configured to include a wireless communication device that performs wireless transmission via a plurality of antennas, and a receiving device that receives a transmission signal transmitted from the wireless communication device. The wireless communication device branches and outputs a transmission signal to one of the plurality of antennas as a reference antenna and the other plurality of antennas as calibration antennas, respectively. Each antenna system on the calibration antenna side is provided with a delay unit that imparts a predetermined delay amount to the transmission signal, a switch that selects one of the plurality of calibration antennas as a calibration target antenna, and a phase shifter that can freely vary the phase of the transmission signal of the selected calibration target antenna. The wireless communication device is provided with a control unit that performs calibration control. The receiving device is connected to a branched output of the received signal that has received the transmission signal and has a frequency spectrum monitor unit that detects the frequency spectrum. The control unit of the wireless communication device sets a predetermined delay amount for the transmission signal of the calibration antenna, selects one calibration target antenna, and when transmitting a transmission signal from the calibration target antenna, determines the deviation of the peak value of the power of the received signal from the center frequency of the signal based on the frequency spectrum output from the frequency spectrum monitor unit of the receiving device, and sets a phase amount for eliminating the deviation in the phase shifter. After sequentially performing the calibration process on the plurality of calibration antennas, the set delay amount is restored. According to such a wireless communication system, calibration of the wireless communication device can be easily performed based on the frequency spectrum detected by the frequency spectrum monitor unit installed on the receiving device side.

[0091] In addition, the receiving device of the wireless communication system may be a wireless relay device. The receiving device is connected to a branched output of the received signal that has received the transmission signal and has a frequency spectrum monitor unit that detects the frequency spectrum. Thereby, calibration of the wireless communication device can be easily performed based on the frequency spectrum detected by the frequency spectrum monitor unit installed on the wireless relay device side.

[0092] In addition, a wireless communication system can be configured to include a wireless communication device that performs wireless transmission via a plurality of antennas, and a receiving device that receives a transmission signal transmitted from the wireless communication device. The wireless communication device branches and outputs the transmission signal to one of the plurality of antennas as a reference antenna and the other plurality of antennas as calibration antennas, respectively. Each antenna system on the calibration antenna side includes a delay unit that imparts a predetermined delay amount to the transmission signal, a switch that selects one of the plurality of calibration antennas as a calibration target antenna, and a phase shifter that can freely vary the phase of the transmission signal of the selected calibration target antenna. The wireless communication device is provided with a control unit that performs calibration control. The receiving device includes a band filter that divides the band of the received signal obtained by receiving the transmission signal into a plurality of bands, a maximum power frequency estimation unit that estimates the frequency of the maximum power based on the power of the received signal after passing through the band filter, and a set phase feedback unit that outputs to the control unit a phase amount for correction corresponding to the maximum power frequency estimated by the maximum power frequency estimation unit. The control unit of the wireless communication device sets a predetermined delay amount for the transmission signal of the calibration antenna, selects one calibration target antenna, and when transmitting the transmission signal from the calibration target antenna, sets the phase amount for correction output from the set phase feedback unit of the receiving device to the phase shifter. After sequentially performing the calibration process on the plurality of calibration antennas, the set delay amount is restored. According to such a wireless communication system, on the receiving device side, it is possible to simply detect the deviation of the center frequency of the signal having the peak value of the power of the received signal without arranging expensive base materials such as a frequency spectrum monitor unit, and the calibration of the wireless communication device can be performed at low cost.

[0093] Note that the calibration method described in the embodiments of the present invention can be realized by causing a processor of a wireless communication device to execute a program prepared in advance. This method is recorded on a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM (Compact Disc-Read Only Memory), a DVD (Digital Versatile Disk), or a flash memory, and is executed by being read from the recording medium by a computer. Further, this method may be distributed via a network such as the Internet.

[0094] Regarding the above-described embodiments, the following additional remarks are disclosed.

[0095] (Supplementary Note 1) In a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas, a delay unit that imparts a predetermined delay amount to a transmission signal transmitted via the antenna; a phase shifter that can variably adjust the phase of a transmission signal transmitted via the antenna; and a control unit that performs calibration control, wherein the control unit uses one of the plurality of antennas as a reference antenna and another one as an antenna to be calibrated, gives transmission signals to each of them, causes the reference antenna to transmit the transmission signal, controls the antenna to be calibrated to transmit the transmission signal to which the predetermined delay amount is imparted, and sets, in the phase shifter, a phase amount for eliminating the deviation based on the deviation of the peak value of the power of the received signal, which is observed on the receiving device side when the transmission signal is transmitted, from the center frequency of the signal. A wireless communication device characterized by the above.

[0096] (Supplementary Note 2) having a plurality of antenna branches each including a plurality of antennas, wherein the control unit Select one antenna of one antenna branch among the plurality of antenna branches as the reference antenna, Select one by one the antennas of other antenna branches among the plurality of antenna branches as the antennas to be calibrated, The wireless communication device according to appended claim 1, comprising processing.

[0097] (Appended claim 3) The control unit After sequentially performing calibration processing on the plurality of calibration antennas, restore the set delay amount, The wireless communication device according to appended claim 1, characterized in that.

[0098] (Appended claim 4) A switch that selects one of the plurality of calibration antennas as the antenna to be calibrated, The wireless communication device according to appended claim 1, characterized by comprising.

[0099] (Appended claim 5) In a wireless communication system including a wireless communication device that performs wireless transmission via a plurality of antennas and a receiving device that receives a transmission signal transmitted from the wireless communication device, The wireless communication device A delay unit that imparts a predetermined delay amount to a transmission signal transmitted via the antenna, A phase shifter that can freely vary the phase of a transmission signal transmitted via the antenna, A control unit that performs calibration control, and The receiving device Receives the transmission signal and has a frequency spectrum monitor unit that detects the frequency spectrum of the received signal, The control unit of the wireless communication device Select one of the plurality of antennas as the reference antenna and another one as the antenna to be calibrated, and give a transmission signal to each, Transmit the transmission signal from the reference antenna, Control is performed to cause the antenna to be calibrated to transmit the transmission signal to which the predetermined delay amount is applied, and Based on the frequency spectrum output from the frequency spectrum monitor unit of the receiving device by the transmission of the transmission signal, a deviation of the peak value of the power of the received signal from the center frequency of the signal is obtained, and a phase amount for eliminating the deviation is set in the phase shifter. A wireless communication system characterized by the above.

[0100] (Appendix 6) The receiving device is a wireless relay device, The receiving device is connected to a branch output of a received signal obtained by receiving the transmission signal, and has a frequency spectrum monitor unit that detects the frequency spectrum. The wireless communication system according to Appendix 5, characterized by the above.

[0101] (Appendix 7) The control unit of the wireless communication device Based on the deviation observed in the receiving device, a phase amount for eliminating the deviation is operationally set in the phase shifter by an operator. The wireless communication system according to Appendix 5, characterized by the above.

[0102] (Appendix 8) In a wireless communication system including a wireless communication device that performs wireless transmission via a plurality of antennas and a receiving device that receives a transmission signal transmitted from the wireless communication device, The wireless communication device A delay unit that applies a predetermined delay amount to a transmission signal transmitted via the antenna, A phase shifter that can variably control the phase of a transmission signal transmitted via the antenna, And a control unit that performs calibration control. The receiving device A band filter that receives the transmission signal and divides the received signal band into a plurality of bands, A maximum power frequency estimation unit that estimates the frequency of the maximum power based on the power of the received signal after passing through the band filter. A set phase feedback unit that outputs a correction phase amount corresponding to the maximum power frequency estimated by the maximum power frequency estimation unit to the control unit. The control unit of the wireless communication device One of the plurality of antennas is used as a reference antenna, and another one is used as an antenna to be calibrated. Transmission signals are given to each of them, Causes the reference antenna to transmit the transmission signal, Controls to cause the antenna to be calibrated to transmit the transmission signal with the predetermined delay amount added thereto, Sets the correction phase amount output from the set phase feedback unit of the receiving device to the phase shifter by transmitting the transmission signal. A wireless communication system characterized by the above.

[0103] (Supplementary Note 9) The control unit of the wireless communication device After sequentially performing calibration processing on a plurality of the calibration antennas, returns the set delay amount. The wireless communication system according to Supplementary Note 5 or 7, characterized by the above.

[0104] (Supplementary Note 10) In a calibration method for a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas, The computer of the wireless communication device Sets a predetermined delay amount in the transmission signal transmitted via the antenna, One of the plurality of antennas is used as a reference antenna, and another one is used as an antenna to be calibrated. Transmission signals are given to each of them, Causes the reference antenna to transmit the transmission signal, Controls to cause the antenna to be calibrated to transmit the transmission signal with the predetermined delay amount added thereto, Based on the deviation of the peak value of the power of the received signal observed on the receiving device side with respect to the center frequency of the signal when transmitting the transmission signal, sets a phase amount that eliminates the deviation. A calibration method characterized by performing processing.

[0105] (Appendix 11) After sequentially performing calibration processing on a plurality of the calibration antennas, restore the set delay amount. The calibration method according to Appendix 10, characterized by performing processing.

[0106] (Appendix 12) In a calibration program for a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas, on a computer of the wireless communication device, set a predetermined delay amount in a transmission signal transmitted via the antenna, use one of the plurality of antennas as a reference antenna and another one as an antenna to be calibrated, and apply a transmission signal to each of them, transmit the transmission signal from the reference antenna, perform control to transmit the transmission signal with the predetermined delay amount applied from the antenna to be calibrated, and set a phase amount for eliminating the deviation based on the deviation of the peak value of the power of the received signal with respect to the center frequency of the signal observed on the receiving device side due to the transmission of the transmission signal. A calibration program characterized by causing the processing to be performed.

[0107] (Appendix 13) After sequentially performing calibration processing on a plurality of the calibration antennas, restore the set delay amount. The calibration program according to Appendix 12, characterized by performing processing.

Explanation of Reference Numerals

[0108] 100 Wireless communication system 110 Transmitting device (wireless communication device, base station device) 111 Antenna element (transmitting antenna) 111a Reference antenna 111b Calibration Antenna Antenna branches 111A, 111B, …, 111N 114 Phase shifter 115 Delay device 150 Receiver (terminal device, wireless relay device) 151, 901 Receiving antenna 201 Transmission signal generation unit 202 Distribution circuit 203 Switch 204 Control unit 211 Received signal demodulation unit 212 Frequency spectrum monitor unit 301 Processor 302 Memory 303 Network IF 305 Recording medium 701 Band filter 702 Received power measurement and maximum power frequency estimation unit 703 Transmission side optimal phase calculation unit 705 Set phase feedback unit 900 Wireless relay device 902 Wireless relay processing unit NW Network

Claims

1. In a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas, a delay unit that applies a predetermined delay amount to a transmission signal transmitted via the antenna; a phase shifter that can variably control the phase of a transmission signal transmitted via the antenna; and a control unit that performs calibration control, wherein the predetermined delay amount is a value used to reduce a frequency deviation observed by the receiving device, and the control unit uses one of the plurality of antennas as a reference antenna and another one as an antenna to be calibrated, gives a transmission signal to each, transmits the transmission signal from the reference antenna, performs control to transmit the transmission signal to which the predetermined delay amount is applied from the antenna to be calibrated, and sets, in the phase shifter, a phase amount for eliminating the deviation based on a deviation of the received signal power peak value observed on the receiving device side with respect to the center frequency of the signal having the peak value when transmitting the transmission signal. A wireless communication device characterized by the above.

2. having a plurality of antenna branches each consisting of a plurality of antennas, and the control unit selects one antenna of one of the plurality of antenna branches as the reference antenna, and sequentially selects a plurality of antennas of other antenna branches of the plurality of antenna branches as antennas to be calibrated, The wireless communication device according to claim 1, comprising the process.

3. The control unit sequentially performs calibration processing on a plurality of antennas to be calibrated, and then restores the set delay amount. The wireless communication device according to claim 1, characterized by the above.

4. The predetermined delay amount is a value in units of one symbol period of a baseband signal. The wireless communication device according to claim 1, characterized by the above.

5. In a wireless communication system including a wireless communication device that performs wireless transmission via a plurality of antennas and a receiving device that receives a transmission signal transmitted from the wireless communication device, the wireless communication device includes a delay unit that applies a predetermined delay amount to a transmission signal transmitted via the antenna, a phase shifter that can variably control the phase of a transmission signal transmitted via the antenna, and a control unit that performs calibration control. The predetermined delay amount is a value used to reduce the deviation of the frequency observed by the receiving device. The receiving device has a frequency spectrum monitor unit that receives the transmission signal and detects the frequency spectrum of the received signal. The control unit of the wireless communication device uses one of the plurality of antennas as a reference antenna and another one as an antenna to be calibrated, gives a transmission signal to each, transmits the transmission signal from the reference antenna, performs control to transmit the transmission signal to which the predetermined delay amount is added from the antenna to be calibrated, and based on the frequency spectrum output from the frequency spectrum monitor unit of the receiving device by the transmission of the transmission signal, obtains the deviation of the center frequency of the signal having the peak value of the power of the received signal, and sets the phase amount for eliminating the deviation in the phase shifter. A wireless communication system characterized by the above.

6. The receiving device is a wireless relay device, The receiving device is connected to a branch output of the received signal that has received the transmission signal and has a frequency spectrum monitor unit that detects the frequency spectrum. The wireless communication system according to claim 5, characterized by the above.

7. In a wireless communication system including a wireless communication device that performs wireless transmission via a plurality of antennas and a receiving device that receives a transmission signal transmitted from the wireless communication device, The wireless communication device has a delay unit that gives a predetermined delay amount to the transmission signal transmitted via the antenna, a phase shifter that can variably control the phase of the transmission signal transmitted via the antenna, and a control unit that performs calibration control, The predetermined delay amount is a value used to reduce the deviation of the frequency observed by the receiving device. The receiving device has a band filter that receives the transmission signal and divides the band of the received signal into a plurality, a maximum power frequency estimation unit that estimates the frequency of the maximum power based on the power of the received signal after passing through the band filter, and a set phase feedback unit that outputs a phase amount for correction corresponding to the maximum power frequency estimated by the maximum power frequency estimation unit to the control unit. The control unit of the wireless communication device uses one of the plurality of antennas as a reference antenna and another one as an antenna to be calibrated, gives a transmission signal to each, transmits the transmission signal from the reference antenna, perform control to cause the antenna to be calibrated to transmit the transmission signal to which the predetermined delay amount is applied, and set the phase amount for correction output from the set phase feedback unit of the receiving device to the phase shifter based on the transmission of the transmission signal, A wireless communication system characterized by this.

8. In a calibration method for a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas, the computer of the wireless communication device sets a predetermined delay amount for the transmission signal transmitted via the antenna, designate one of the plurality of antennas as a reference antenna and the other as an antenna to be calibrated, apply a transmission signal to each, cause the reference antenna to transmit the transmission signal, the predetermined delay amount is a value used to reduce the frequency deviation observed by the receiving device, perform control to cause the antenna to be calibrated to transmit the transmission signal to which the predetermined delay amount is applied, and set a phase amount that eliminates the deviation based on the deviation of the center frequency of the signal having the peak value of the power of the received signal observed on the receiving device side due to the transmission of the transmission signal, A calibration method characterized by performing the process.

9. In a calibration program for a wireless communication device that performs wireless communication with a receiving device via a plurality of antennas, on the computer of the wireless communication device, set a predetermined delay amount for the transmission signal transmitted via the antenna, designate one of the plurality of antennas as a reference antenna and the other as an antenna to be calibrated, apply a transmission signal to each, cause the reference antenna to transmit the transmission signal, the predetermined delay amount is a value used to reduce the frequency deviation observed by the receiving device, perform control to cause the antenna to be calibrated to transmit the transmission signal to which the predetermined delay amount is applied, and set a phase amount that eliminates the deviation based on the deviation of the center frequency of the signal having the peak value of the power of the received signal observed on the receiving device side due to the transmission of the transmission signal, A calibration program characterized by causing the process to be performed.

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