JP2006319412A - Wireless receiver and wireless transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique calibrating a broadband transmission/reception signal with high accuracy without deteriorating the communication quality of the transmission/reception signal and causing reduction in the throughput. <P>SOLUTION: Each of signal multiplexing sections 112 multiplexes a reference signal on a received signal to calculate an amplitude error and a phase error given by a wireless reception system 113. The reference signal multiplexed by each of the signal multiplexing sections 112 is one or more subcarrier signals whose frequency is orthogonal to the frequency of a multicarrier signal. The frequency of the reference signals in this case is orthogonal to that of the other subcarriers in the received signals. An inter-wireless-system error calculation section 126 separates the reference signals multiplexed on the received signals, compares the respective received signals and calculates errors of the respective received signals. An error correction section 122 corrects the received signals of respective wireless reception units 110 on the basis of the errors of the received signals calculated by the inter-wireless-system error calculation section 126. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio reception apparatus and radio transmission apparatus that perform communication using a multicarrier signal, and more particularly to a radio reception apparatus and radio including an array antenna such as an adaptive array antenna that controls antenna directivity by a plurality of antenna elements. The present invention relates to a transmission device.

  2. Description of the Related Art Conventionally, there is known an adaptive array antenna type wireless transmission / reception apparatus that includes a plurality of wireless units and controls antenna directivity by performing phase and amplitude weighting processing on signals transmitted and received via these wireless units. (For example, refer to Patent Document 1). According to such an adaptive array antenna type radio transmission / reception apparatus, the ratio of signal to interference wave of a signal to be transmitted / received can be improved by adaptively changing the antenna directivity. Frequency utilization efficiency and communication quality can be improved.

However, in the above-described adaptive array antenna type wireless transmission / reception apparatus, the antenna directivity of the wireless transmission / reception apparatus is impaired because a weight different from the initial setting is added to a signal to be transmitted / received due to an individual difference of each wireless unit. May be. For this reason, in an adaptive array antenna type wireless transmission / reception apparatus, it is necessary to periodically observe the phase or amplitude of a transmission / reception signal to which a weight has been added to perform correction. Therefore, a technique of a calibration method that appropriately calibrates weights based on the observed value of the phase or amplitude of the transmission / reception signal is also disclosed (see, for example, Patent Document 2). In the calibration method according to this technique, each calibration signal is extracted from the reception signal multiplexed with the calibration signal, and the distortion is calculated by individually comparing the phase and amplitude of each calibration signal. Then, the received signal is weighted based on the calculated distortion information. By performing such weighting processing, the distortion of the received signal caused by the signal processing of each wireless transmission / reception unit is eliminated.
JP-A-9-219615 JP 2002-353865 A

  However, in the transmission / reception signal calibration method disclosed in Patent Document 2, when the calibration signal is time-multiplexed or code-multiplexed, the multiplexed calibration signal becomes an interference source for the transmission / reception signal. Communication quality may be degraded. In addition, if a time is provided in a transmission / reception signal or a code or a frequency is assigned to multiplex calibration signals, the amount of data communication may be reduced and throughput may be reduced. Furthermore, when the frequency of the transmission / reception signal is wide, the deviation of the amplitude and phase error within the band becomes large, so that the calibration accuracy may be deteriorated.

  The present invention has been made in view of the above points, and is an array that performs communication using a multicarrier signal that can calibrate a wideband transmission / reception signal with high accuracy without deterioration in communication quality or throughput of the transmission / reception signal. An object of the present invention is to provide an antenna-type radio transmission apparatus and radio reception apparatus.

  A radio receiving apparatus according to the present invention is an array antenna type radio receiving apparatus that includes a plurality of antennas and a plurality of receiving means and performs communication using multicarrier signals, and is at least orthogonal to the multicarrier signals. Reference signal generating means for generating a reference signal including one or more subcarrier signals having a frequency relationship, signal multiplexing means for multiplexing the received signal and the reference signal, and each of the plurality of receiving means An error calculation unit that separates the reference signal multiplexed with the reception signal, compares the separated reference signals, and calculates an error value of the reception signal in each of the reception units, and is calculated by the error calculation unit Based on the error value of the reception signal, the reception signal processing means for correcting the reception signal in each of the reception means is employed.

  According to such a configuration, since the frequency of the reference signal to be multiplexed and the frequency of the other subcarrier signal of the received signal are in an orthogonal frequency relationship, the reference signal does not become an interference wave for the received signal. Quality deterioration can be prevented.

  In addition to the configuration of the invention described above, the radio receiving apparatus according to the present invention further transmits channel fluctuation estimation information of the received signal to the reference signal generating means, and the frequency of the reference signal is a subcarrier signal having a small received electric field strength. The system is provided with a channel estimation means for setting the frequency to a predetermined frequency.

  According to such a configuration, in addition to the effect of the present invention, when there is an unusable frequency, the frequency of the reference signal to be multiplexed is assigned according to the situation of the fading environment. For this reason, it is not necessary to provide a frequency, code, or time for the reference signal, so that a decrease in data throughput in communication is eliminated. Therefore, the error of the received signal in the receiving circuit can be calibrated even during communication.

  In addition to the configuration of the above invention, the radio reception apparatus according to the present invention further calculates an error correction value in each subcarrier signal based on a plurality of error values obtained in a predetermined time by the error calculation means. In this case, an averaging processing means for performing an error correction value averaging process is employed.

  According to such a configuration, in addition to the effect of the present invention, since the subcarrier signal having a small received electric field strength fluctuates due to fading fluctuation within a certain time, the error value obtained by the calibration method also includes a plurality of error values. It can be obtained for subcarrier signals. Therefore, by using these error values, calibration can be performed by averaging the error values in the frequency direction even in a wideband signal, so that highly accurate calibration can be realized.

  A radio transmission apparatus according to the present invention is an array antenna type radio transmission apparatus that includes a plurality of antennas and a plurality of transmission means and performs communication using a multicarrier signal, and at least for the multicarrier signal. Each of a plurality of transmission means, a reference signal generation means for generating a reference signal including one or more subcarrier signals that have an orthogonal frequency relationship, a signal multiplexing means for multiplexing a transmission signal and a reference signal, and An error calculation unit that separates a reference signal that is multiplexed into a transmitted signal that has passed, compares the separated reference signals, and calculates an error value of the transmission signal in each of the transmission units, and is calculated by the error calculation unit And a transmission signal processing means for correcting the transmission signal in each of the transmission means based on the error value of the transmitted signal. .

  According to such a configuration, the frequency of the reference signal to be multiplexed and the frequency of the other subcarrier signal of the transmission signal are in an orthogonal frequency relationship, so the reference signal does not become an interference wave for the transmission signal. Quality deterioration can be prevented.

  The radio transmission apparatus according to the present invention employs a configuration in which, in the configuration of the present invention, the signal multiplexing means multiplexes the reference signal with the subcarrier signal not used for communication within the band of the transmission signal.

  According to such a configuration, in addition to the effect of the invention, for example, when there is a subcarrier signal that is not used in the transmission signal, the frequency of the reference signal to be multiplexed is determined according to the reception electric field at the terminal. Since the frequency of the subcarrier signal that is not used is assigned, it is not necessary to provide the frequency, code, time, and the like for the reference signal. As a result, the data throughput in communication is not reduced, and the error of the transmission signal in the transmission circuit can be calibrated during communication.

  In addition to the configuration of the invention, the radio transmission apparatus according to the present invention calculates an error correction value in each subcarrier signal based on a plurality of error values obtained in a predetermined time by the error calculation means, A configuration including an averaging processing means for performing an averaging process of correction values is employed.

  According to such a configuration, in addition to the effects of the present invention, for example, when there is a fading fluctuation within a certain time and a transmission electric field fluctuates in a terminal, a subcarrier signal not used in communication is changed. Therefore, error values obtained by the above calibration method can also be obtained for a plurality of subcarrier signals. Therefore, by using these error values, calibration can be performed by averaging the error values in the frequency direction even in a wideband signal, so that highly accurate calibration can be performed.

  According to the present invention, in an array antenna type wireless transceiver that performs communication using multicarrier signals, there is no reduction in throughput during communication, and the reference signal does not become an interference wave with respect to the transmitted and received signals. Can be calibrated with high accuracy.

<Summary of invention>
The present invention relates to an array antenna type wireless transmission / reception apparatus that performs communication using a multicarrier signal, and uses a reference signal for calibrating the error as an amplitude and phase error received by each wireless transmission / reception circuit as a transmission / reception signal. Multiplex. At this time, by setting the frequency of the reference signal to a relationship between the subcarriers of the transmission / reception signal and the orthogonal frequency, the reference signal does not become an interference wave with respect to the transmission / reception signal, so that deterioration of communication quality can be prevented. In addition, the frequency for multiplexing the reference signal is a subcarrier frequency with a small received electric field strength from the estimated channel fluctuation value for a received signal, and a subcarrier frequency that is not used for a transmitted signal. Calibration can be performed without a decrease in the frequency, and in the case of a wideband signal, the error calibration can be performed with higher accuracy by obtaining the error calibration from a plurality of error values obtained in a certain fixed time.

  Hereinafter, with reference to the drawings, some of the embodiments of the wireless transmission / reception apparatus according to the present invention will be described in detail for a wireless reception apparatus and a wireless transmission apparatus. In the drawings used in the embodiments, the same components are denoted by the same reference numerals, and redundant description is omitted as much as possible.

<Embodiment 1>
In Embodiment 1, a wireless reception device will be described. 1 is a block diagram showing a configuration of an array antenna receiving apparatus according to Embodiment 1 of the present invention. The array antenna receiving apparatus according to Embodiment 1 is an adaptive array antenna type receiving apparatus that performs communication using OFDM (Orthogonal Frequency Division Multiple) signals, and includes a plurality of radio receiving units 110, The baseband unit 120, the reception system selection unit 131, and the reference signal transmission system 132 are provided.

  Each of the plurality of radio reception units 110 includes an antenna unit 111, a signal multiplexing unit 112, and a radio reception system 113. Furthermore, the baseband unit 120 includes an FFT unit 121 that performs time-frequency conversion processing on the OFDM signal, an error correction unit 122 that performs error correction, an array processing unit 123 that performs signal arrival direction estimation, and the like, and a received signal A demodulation unit 124, a reference signal demodulation unit 125, an inter-radio system error calculation unit 126 that calculates an amplitude and phase error in each received signal, and a reference signal generation unit 127 are provided. Note that the number of FFT units 121, error correction units 122, and reference signal demodulation units 125 is the same as the number of radio reception units 110, respectively.

  Each of the plurality of antenna units 111 receives a radio signal transmitted from a communication partner. An array antenna is configured by regularly arranging a plurality of antenna units 111. The signal multiplexing unit 112 is configured by a directional coupler, a synthesizer, and the like. The received signal input from the antenna unit 111 is generated by the reference signal generation unit 127 and is up-converted or leveled by the reference signal transmission system 132. Multiplex the adjusted reference signal. Note that the signal multiplexing unit 112 preferably includes a band-pass filter or the like that can block the reference signal so that the reference signal does not flow into the antenna unit 111 side. The wireless reception system 113 includes a low noise amplifier, a mixer, an attenuator, and the like, and performs amplification of the received signal, frequency conversion, gain adjustment, and the like.

  In the baseband unit 120, the FFT unit 121 includes an FFT circuit for performing time-frequency conversion processing on each received signal. The reference signal demodulator 125 includes a demodulation circuit that detects the amplitude and phase of the reference signal multiplexed with the received signal. Further, the plurality of inter-radio-system error calculation units 126 compare the amplitude / phase information of the respective reference signals detected by the respective reference signal demodulation units 125, thereby providing each received signal received by the radio reception system 113. A calculation circuit for calculating a correction value for each signal from the amplitude and phase error between the wireless systems is provided.

  The error correction unit 122 includes a weighting circuit that corrects amplitude and phase errors in each received signal based on the error correction value calculated by the inter-radio system error calculation unit 126. The array processing unit 123 includes a signal processing circuit that performs signal processing such as direction-of-arrival estimation and interference wave suppression from the received signal in order to control the directivity of the array antenna. The reception signal demodulation unit 124 includes a demodulation circuit that performs despreading and demodulation on a signal used in communication. Each of the above circuits is a part of the baseband unit 120, and each circuit can be realized by a digital signal processing circuit such as an ASIC or FPGA.

  The reception system selection unit 131 includes a semiconductor switch or the like, selects a desired radio reception system from a plurality of radio reception systems as appropriate or periodically, and a signal multiplexing unit corresponding to the selected radio reception system A reference signal is output to 112. The reference signal generator 127 includes a clock generator and the like, and generates a reference signal having a predetermined frequency and amplitude. The reference signal transmission system 132 is configured by an amplifier, a mixer, an attenuator, or the like, and performs amplification, frequency conversion, gain adjustment, and the like on the reference signal input from the reference signal generation unit 127.

  Next, the operation of the array antenna receiving apparatus according to Embodiment 1 shown in FIG. 1 will be described. A reception signal received by the antenna unit 111 is input to the signal multiplexing unit 112. Further, the reference signal generator 127 generates a reference signal whose amplitude and phase are known by a clock generator or the like so as to have a frequency having a relationship of orthogonal frequency with each subcarrier frequency, and this reference signal is used as the reference signal. Transmit to the transmission system 132. The frequency at this time may be a subcarrier frequency set in advance for multiplexing the reference signal, or may be a frequency not used in communication. The reference signal transmission system 132 performs processing such as frequency conversion and gain adjustment, and transmits the reference signal to the reception system selection unit 131.

  The reception system selection unit 131 selects the radio reception unit 110 specified by the baseband unit 120 or each radio reception unit 110 periodically, and sends the reference signal to the signal multiplexing unit 112 of the selected radio reception unit 110. Send. Then, the signal multiplexing unit 112 multiplexes the reception signal input from the antenna unit 111 and the reference signal input from the reception system selection unit 131, and transmits this multiplexed reception signal to the radio reception system 113. Further, the wireless reception system 113 performs processing such as frequency conversion and gain adjustment, and transmits a reception signal to the baseband unit 120.

  In the baseband unit 120, the FFT unit 121 performs time-frequency conversion processing so that the received signal can be processed by each subcarrier. Among the subcarriers subjected to the time-frequency conversion processing by the FFT unit 121, the subcarrier of the reference signal is transmitted to the reference signal demodulation unit 125, and the subcarriers other than the reference signal are transmitted to the error correction unit 122. The reference signal demodulator 125 demodulates the subcarriers of the reference signal and detects amplitude and phase values. Then, the detected amplitude and phase values are transmitted to the inter-wireless system error calculation unit 126. The inter-radio-system error calculation unit 126 receives the amplitude and phase values of the reference signal multiplexed on the reception signal that has passed through each radio reception unit. Then, the inter-radio-system error calculation unit 126 compares the amplitude and phase values of each reference signal, and detects an error of the reception signal given by each radio reception unit. Further, the inter-radio system error calculation unit 126 calculates an error correction value of the amplitude and phase of each received signal from the detected error value, and transmits the error correction value to the error correction unit 122.

  The error correction unit 122 adjusts the amplitude and phase of each received signal according to the error correction value, and transmits the adjusted signal to the array processing unit 123. The array processing unit 123 executes signal processing for performing directivity control of the array antenna such as arrival direction estimation for each received signal, and transmits the signal to the received signal demodulation unit 124. Received signal demodulation section 124 performs demodulation processing on the signal of each subcarrier. At this time, the frequencies of the subcarriers have an orthogonal frequency relationship, and the reference signal that was originally multiplexed is the same, so there is no interference between the subcarriers and the interference of the reference signals. There is no degradation of communication quality due to

  As described above, according to the array antenna receiving apparatus according to Embodiment 1, the signal multiplexing unit 112 multiplexes the reference signal with respect to the received signal in order to calculate the amplitude and phase errors given by the radio receiving system 113. Turn into. In this case, the frequency of the reference signal is set to a frequency that has an orthogonal frequency relationship with respect to other subcarriers in the received signal. Accordingly, since the reference signal does not become an interference wave with respect to the received signal, the received signal can be calibrated with high accuracy without degrading the communication quality.

  Note that the array antenna receiving apparatus according to Embodiment 1 may be applied or modified as follows. That is, in the first embodiment, the number of subcarriers of the reference signal is not mentioned, but a plurality of subcarriers are generated as reference signals, and an error value is calculated for each of them, which is high even in a wideband signal. Accuracy calibration can be performed. In Embodiment 1, the error of each received signal is calculated by comparing the reference signal multiplexed with each received signal. However, the reference signal generated from the reference signal generating unit 127, A similar effect can be obtained by comparing a reference signal multiplexed with each received signal. In the first embodiment, the reference signal to be multiplexed to each received signal is described as being within the signal band. However, the reference signal is not within the signal band, but within a band where time-frequency conversion can be performed by the FFT unit 121. A similar effect can be obtained if the frequency is in a relationship of orthogonal frequency with each subcarrier of the received signal.

<Embodiment 2>
In the second embodiment, a wireless reception apparatus will also be described. FIG. 2 is a block diagram showing a configuration of an array antenna receiving apparatus according to Embodiment 2 of the present invention. The array antenna receiving apparatus according to the second embodiment has a configuration in which a channel estimation unit 221 is added to the baseband unit 120 of the array antenna receiving apparatus in the first embodiment. Therefore, in the second embodiment, the baseband unit 220 is displayed with a different code.

  Other constituent elements of the array antenna receiving apparatus according to the second embodiment exhibit the same functions as the constituent elements of the array antenna receiving apparatus according to the first embodiment. Therefore, about the component which exhibits the same function, the same code | symbol as Embodiment 1 is attached | subjected and the description is abbreviate | omitted.

  FIG. 3 is a waveform diagram of signals transmitted from the terminal to the base station in the configuration of the array antenna receiving apparatus shown in FIG. Therefore, the operation of the array antenna receiving apparatus will be described with reference to the configuration diagram of FIG. 2 and the waveform diagram of FIG. The channel estimation unit 221 analyzes the frequency fading status of each subcarrier signal output from the FFT unit 121 from its amplitude and phase.

  That is, as shown in FIG. 3, the received signal level in the band of the transmission signal as shown in (a) transmitted from the terminal fluctuates due to the influence of multipath or the like in the propagation path. In such a case, the signal received by the base station may include a subcarrier signal having an extremely low received electric field level due to the influence of frequency fading as shown in (b). Information carried on such a subcarrier signal cannot be received by the base station. In a multicarrier signal such as an OFDM signal, the fading status can be known from the amplitude and phase of each subcarrier signal. Therefore, the channel estimation unit 221 identifies a subcarrier signal having a reception electric field level that is so low that the data cannot be received, and transmits the channel estimation value to the reference signal generation unit 127.

  The reference signal generator 127 sets the frequency of the reference signal from the received channel estimation value to a subcarrier frequency having a low received signal level, and generates a reference signal as shown in (d). As a result, the reference signal of (d) multiplexed on the received signal shown in (c) becomes a subcarrier signal whose received electric field level is so low that data cannot be received in the received signal, as shown in (e). Multiplexed. Since the data of the received signal cannot be received from the beginning, there is no influence by multiplexing the reference signal on the entire throughput. Further, the subcarrier of the same frequency of the received signal with respect to the reference signal has a very small level and does not affect the calibration accuracy.

  As described above, according to the array antenna receiving apparatus of the second embodiment, data is transmitted even during communication by multiplexing a reference signal with a subcarrier signal having a low reception electric field level among subcarrier signals of a reception signal. Thus, accurate calibration can be performed.

<Embodiment 3>
In the third embodiment, a wireless reception apparatus will also be described. FIG. 4 is a block diagram showing a configuration of an array antenna receiving apparatus according to Embodiment 3 of the present invention. The array antenna receiving apparatus according to the third embodiment has a configuration in which an averaging processing unit 321 is added to the baseband unit 220 in the array antenna receiving apparatus in the second embodiment. Therefore, in the third embodiment, the baseband unit 320 is displayed with a different code.

  Other components of the array antenna receiving apparatus according to Embodiment 3 exhibit the same functions as those of the array antenna receiving apparatus according to Embodiments 1 and 2. Therefore, about the component which exhibits the same function, the same code | symbol as Embodiment 1 and Embodiment 2 is attached | subjected, and the description is abbreviate | omitted.

  FIG. 5 is a waveform diagram of a received signal on which a reference signal is multiplexed and a subcarrier from which a correction value is obtained in the configuration of the array antenna receiving apparatus shown in FIG. Therefore, the operation of the array antenna receiving apparatus according to Embodiment 3 will be described with reference to the configuration diagram of FIG. 4 and the waveform diagram of FIG.

  The averaging processing unit 321 stores the error correction value obtained by the inter-wireless error calculation unit 126 for a certain period of time. When the frequency fading is not constant within a certain time, the frequency characteristics of the frequency fading change as shown in FIGS. 5A and 5B, and the subcarrier having a small received electric field level also changes. Under such circumstances, when error correction values based on, for example, four reference signals are acquired, four error correction values of subcarriers of different frequencies are obtained as shown in FIG. A wideband signal has frequency characteristics in amplitude and phase within the signal band. Therefore, there is a difference in frequency characteristics depending on the components and environmental conditions of each radio reception system. Therefore, by performing averaging in the frequency direction using four error correction values, error correction values can be obtained for other subcarriers without error correction values, including deviations in frequency characteristics in wideband signals. Calibration can be performed.

  As described above, according to the array antenna receiving apparatus according to the third embodiment, subcarriers with small received electric field strengths fluctuate due to fading fluctuations within a certain period of time, and thus errors obtained by the calibration method as described above. Values can also be obtained for multiple subcarriers. By using a plurality of error values in this way, error values can be calibrated even in a wideband signal by averaging the error values in the frequency direction, so that calibration can be performed with high accuracy.

<Embodiment 4>
In the fourth embodiment, a wireless transmission device will be described. FIG. 6 is a block diagram showing a configuration of an array antenna transmission apparatus according to Embodiment 4 of the present invention. The array antenna transmission apparatus according to Embodiment 4 is an adaptive array antenna type transmission apparatus that performs communication using OFDM signals, and includes a plurality of radio transmission units 410, a baseband unit 420, and a transmission system selection unit 431. And a reference signal receiving system 432. Each of the plurality of wireless transmission units 410 includes an antenna unit 411, a signal separation unit 412, and a wireless transmission system 413.

  The baseband unit 420 includes a transmission signal modulation unit 424, a reference signal generation unit 425, an IFFT unit 423 that performs frequency-time conversion processing of the transmission signal, and an array processing unit that weights the amplitude and phase of the transmission signal. 422, an error correction unit 421 that corrects amplitude and phase errors given to the transmission signal, an FFT unit 427 that performs time-frequency conversion processing on the transmission signal on which the reference signal is multiplexed, and a reference for demodulating the reference signal The configuration includes a signal demodulation unit 428 and a wireless system error calculation unit 426 that calculates a wireless system error.

  In baseband section 420, transmission signal modulation section 424 includes a modulation circuit that distributes data to a plurality of subcarriers and performs processing such as spreading for each subcarrier. The reference signal generation unit 425 includes a clock generator and the like, and generates a reference signal having a predetermined frequency and amplitude. The IFFT unit 423 includes an IFFT circuit that performs frequency-time conversion processing on a transmission signal that is a signal for each subcarrier input from the transmission signal modulation unit 424.

  The array processing unit 422 includes a weighting circuit that distributes a transmission signal to each wireless transmission unit and weights the amplitude and phase according to directivity control of the array antenna. The FFT unit 427 includes a conversion processing circuit that performs time-frequency conversion processing on the transmission signal. The inter-radio system error calculation unit 426 has a function of calculating the amplitude and phase error in each radio transmission system from the phase information of the reference signal multiplexed on each transmission signal obtained from the reference signal demodulation unit 428. . The error correction unit 421 includes a weighting circuit that corrects the amplitude and phase of a transmission signal sent to each wireless transmission system using the error correction value calculated by the wireless system error calculation unit 426. Each of the above circuits is a part of the circuit constituting the baseband unit 420 and can be realized by a digital signal processing circuit such as an ASIC or FPGA.

  The wireless transmission system 413 includes an amplifier, a mixer, and the like, and performs transmission signal amplification, frequency conversion, gain adjustment, and the like. The signal separation unit 412 includes a directional coupler, a distributor, and the like, and distributes or extracts a part of the transmission signal from the transmission signal input from the wireless transmission system 413 to extract the antenna unit 411 and the transmission system selection unit. To 431. The antenna unit 411 transmits a radio signal. Note that an array antenna is configured by regularly arranging a plurality of antenna portions 411.

  The transmission system selection unit 431 is configured by a semiconductor switch or the like, and selects a transmission signal or a part thereof from the selected radio reception system signal separation unit 412 by appropriately or periodically selecting from a plurality of radio transmission units. Is entered. The reference signal reception system 432 includes an amplifier, a mixer, an attenuator, and the like, and performs amplification, frequency conversion, gain adjustment, and the like on the signal input from the transmission system selection unit 431.

  Next, the operation of the array antenna transmission apparatus according to the fourth embodiment shown in FIG. 6 will be described. The transmission signal modulation unit 424 divides the data into subcarriers, performs modulation processing such as spreading, and sends the data to the IFFT unit 423. Also, the reference signal generation unit 425 generates pilot signals having existing amplitudes and phases at frequencies of subcarriers that are not used and sends them to the IFFT unit 423. Then, IFFT section 423 performs frequency-time conversion processing on the transmission signal and the reference signal capital, thereby converting the signals that are a plurality of subcarriers into one signal and sending it to array processing section 422.

  The array processing unit 422 distributes the transmission signal to each wireless transmission unit 410 and weights the amplitude and phase of each transmission signal so as to obtain a desired antenna directivity. The signal weighted by the array processing unit 422 is input to the error correction unit 421. In the initial stage where there is no correction value, the signal is sent to each wireless transmission system 413 without being corrected.

  Each wireless transmission system 413 performs frequency conversion, gain adjustment, and amplification on the transmission signal, and transmits the result to the signal separation unit 412. The transmission system selection unit 431 is connected to the signal separation unit 412 of the wireless transmission unit 410 that is controlled by the baseband unit 420 or periodically selected. The signal separation unit 412 distributes the transmission signal in two and sends it to the transmission system selection unit 431 and the antenna unit 411, and the antenna unit 411 radiates the transmission signal. In this case, the transmission signal radiated from each wireless transmission unit 410 is weighted in amplitude and phase, and has a predetermined directivity by the array antenna.

  The signal input to the transmission system selection unit 431 is sent to the reference signal reception system 432, undergoes processing such as frequency conversion, amplification, and gain adjustment, and is sent to the FFT unit 427. The FFT unit 427 performs time-frequency conversion on the transmission signal that has passed through the reference signal reception system 432, and extracts the signal of each subcarrier. Among these subcarrier signals, only a subcarrier having a reference signal is sent to the reference signal demodulator 428, and the amplitude and phase of the reference signal are detected and stored. The reference signal demodulator 428 demodulates the subcarriers of the reference signal and detects amplitude and phase values. The detected amplitude and phase values are transmitted to the inter-wireless system error calculation unit 426. The transmission system selection unit 431 repeats the same operation for all the wireless transmission units, detects the amplitude and phase of the reference signal multiplexed on each transmission signal, and stores them.

  The wireless inter-system error calculation unit 426 compares the amplitude and phase of each reference signal stored in memory, and calculates the difference. Based on this difference, an error correction value in each wireless transmission unit 410 is calculated and sent to the error correction unit 421. The error correction unit 421 adjusts the weighting of the amplitude and phase in each transmission signal based on the error correction value. Since the adjusted transmission signal is accurately weighted when the signal is radiated from the antenna unit 411, a desired antenna directivity can be obtained.

  As described above, the array antenna transmission apparatus according to Embodiment 4 multiplexes the reference signal with the transmission signal in order to calculate the amplitude and phase error given by the wireless transmission system. The frequency of the reference signal at that time is a frequency that is in a relationship of orthogonal frequency with respect to other subcarriers in the transmission signal, so that it does not become an interference wave with respect to the transmission signal. The transmission signal can be calibrated with high accuracy. Further, since only the reference signal in the transmission signal needs to be demodulated to detect the amplitude and phase, the scale of the demodulation circuit can be reduced.

  The array antenna transmission apparatus according to the fourth embodiment can be applied or modified as follows. In the fourth embodiment, the number of subcarriers of the reference signal is not mentioned, but a plurality of subcarriers are generated as reference signals, and an error value is calculated for each of them, thereby enabling high-accuracy calibration even for a wideband signal. It can be performed. Further, in Embodiment 4, the error of each transmission signal is calculated by comparing the reference signal multiplexed with each transmission signal, but the reference signal generated from the reference signal generation unit 425, The same effect can be obtained by comparing the reference signals multiplexed with each transmission signal. In Embodiment 4, a part of each transmission signal is extracted by the signal separation unit 412. However, the same effect can be obtained by extracting only the reference signal by the signal separation unit 412 using a filter or the like.

<Embodiment 5>
Embodiment 5 also describes a wireless transmission device. FIG. 7 is a block diagram showing a configuration of an array antenna transmission apparatus according to Embodiment 5 of the present invention. The array antenna transmission apparatus according to the fifth embodiment differs from the array antenna transmission apparatus according to the fourth embodiment in that a radio reception unit 510 having an antenna unit 511 and a radio reception system 512 is added, The reception signal processing unit 521 is added to the unit 520. Therefore, in the array antenna transmission apparatus of FIG. 7, the code is changed to a baseband unit 520. Note that the array antenna transmission apparatus shown in FIG. 7 constitutes a radio reception unit 510 and one radio base station. Further, the relationship between the terminal and the radio base station may be reversed. Many of the constituent elements of the array antenna transmission apparatus according to the fifth embodiment exhibit the same functions as the constituent elements of the array antenna transmission apparatus in the fourth embodiment. Therefore, the constituent elements that exhibit the same function are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 7, the wireless reception system 512 includes an amplifier, a mixer, a variable attenuator, and the like, and performs amplification of a received signal, frequency conversion, gain adjustment, and the like. The received signal processing unit 521 performs synchronous detection and demodulation of the received signal and extracts information such as data. The received signal processing unit 521 is a circuit that constitutes the baseband unit 520, and is constituted by a digital signal processing circuit such as an ASIC or FPGA.

  Next, the operation of the array antenna transmission apparatus configured as described above will be described. In the terminal that has received the transmission signal, information on the received electric field strength in each subcarrier of the reception signal at the terminal is transmitted on the transmission signal of the terminal. The antenna unit 511 of the wireless reception unit 510 receives the signal, and the wireless reception system 512 performs processing such as amplification, frequency conversion, and gain adjustment, and transmits the processed signal to the reception signal processing unit 521. Received signal processing section 521 demodulates the received signal and transmits received field strength information of each subcarrier carried by the terminal to transmission signal modulating section 424 and reference signal generating section 425. Transmission signal modulation section 424 does not transmit data on subcarriers with low electric field strength at the terminal, and transmits data on other subcarriers. As a result, the data throughput does not decrease. At that time, the reference signal generator 425 generates pilot signals on subcarriers that are not used for data transmission and multiplexes them with transmission signals. Calibration of each transmission signal can be performed with high accuracy using this reference signal.

  As described above, according to the array antenna transmission apparatus of the fifth embodiment, when there is a subcarrier that is not used among the subcarriers of the transmission signal, the reference signal is generated on the subcarrier that is not used and the transmission signal is converted into the transmission signal. By multiplexing, there is no need to provide a subcarrier for the reference signal, and data can be calibrated with high accuracy without a decrease in data throughput even during communication.

  The array antenna transmission apparatus according to the fifth embodiment may be applied or modified as follows. In the fifth embodiment, the antenna unit 511 of the wireless reception unit 510 has been described as a single calibration, but it may be shared with the antenna unit 411 of the wireless transmission unit 410 using an antenna duplexer or a switch. In the fifth embodiment, the case where the frequency bands of the transmission signal and the reception signal are different has been described. For example, when the reception signal is also an OFDM signal and communication using a TDD communication method using the same frequency band is performed, The reception signal processing unit 521 may detect the reception electric field strength of each subcarrier and determine the subcarrier that generates the reference signal based on the information.

<Embodiment 6>
In the sixth embodiment, a wireless transmission device will also be described. FIG. 8 is a block diagram showing a configuration of an array antenna transmission apparatus according to Embodiment 6 of the present invention. The array antenna transmission apparatus according to the sixth embodiment is obtained by adding an averaging processing unit 621 to the baseband unit 520 of the array antenna transmission apparatus in the fifth embodiment. Therefore, in the array antenna receiving apparatus according to the sixth embodiment, the code is changed to a baseband unit 620. Other components exhibit the same functions as the components of the array antenna transmission apparatus in the fifth embodiment. Therefore, about the component which exhibits the same function, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  Next, the operation of the array antenna transmission apparatus according to the sixth embodiment shown in FIG. 8 will be described. The averaging processing unit 621 stores the error correction value obtained by the inter-wireless error calculation unit 426 for a certain period of time. When the received electric field strength of each subcarrier in the terminal is not constant within a certain time, the subcarriers that do not transmit data are not constant and become a plurality of subcarriers within the signal band. For example, when four error correction values are acquired, four error correction values of subcarriers of different frequencies are obtained. A wideband signal has frequency characteristics in amplitude and phase within the signal band. Therefore, there is a difference in frequency characteristics depending on components and environmental conditions of each wireless transmission system. Therefore, by performing averaging in the frequency direction using the four correction values, it is possible to obtain correction values for other subcarriers that do not have correction values, and with high accuracy including deviations in frequency characteristics in wideband signals. Calibration can be performed.

  As described above, according to the array antenna transmission apparatus according to Embodiment 6, by changing the subcarrier that generates the reference signal within a certain time based on the received electric field strength of each subcarrier at the terminal, Error correction values can be obtained for a plurality of subcarriers. By using the plurality of error values, it is possible to calibrate by averaging error values in the frequency direction even in a wideband signal, so that highly accurate calibration can be performed.

  According to the calibration method of the array antenna transmission / reception apparatus according to the present invention, the frequency of the reference signal to be multiplexed into the multicarrier signal is multiplexed as the relationship between each subcarrier and the orthogonal frequency, so that the reference signal is multiplexed. Therefore, the present invention can be applied to uses such as an array antenna type wireless transmission / reception apparatus and a transmission / reception signal calibration method that need to avoid the problem that the reference signal becomes noise of the transmission / reception signal and lowers the calibration accuracy.

FIG. 1 is a block diagram showing a configuration of an array antenna receiving apparatus according to Embodiment 1 of the present invention. The block diagram which shows the structure of the array antenna receiver which concerns on Embodiment 2 of this invention Waveform diagram of signal transmitted from terminal to base station in configuration of array antenna receiving apparatus shown in FIG. The block diagram which shows the structure of the array antenna receiver which concerns on Embodiment 3 of this invention. FIG. 4 is a waveform diagram of a subcarrier from which a received signal and a correction value are obtained in which a reference signal is multiplexed in the configuration of the array antenna receiving apparatus shown in FIG. The block diagram which shows the structure of the array antenna transmitter which concerns on Embodiment 4 of this invention. The block diagram which shows the structure of the array antenna transmitter which concerns on Embodiment 5 of this invention. The block diagram which shows the structure of the array antenna transmitter which concerns on Embodiment 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 Radio reception unit 111 Antenna part 112 Signal multiplexing part 113 Wireless reception system 120,220,320,420,520,620 Baseband part 121 FFT part 122 Error correction part 123 Array processing part 124 Reception signal demodulation part 125 Reference signal demodulation part 126 Inter-Radio System Error Calculation Unit 127 Reference Signal Generation Unit 131 Reception System Selection Unit 132 Reference Signal Transmission System 221 Channel Estimation Unit 321 Averaging Processing Unit 410 Radio Transmission Unit 411 Antenna Unit 412 Signal Separation Unit 413 Radio Transmission System 421 Error Correction Unit 422 Array processing unit 423 IFFT unit 424 Transmission signal modulation unit 425 Reference signal generation unit 426 Inter-radio system error calculation unit 521 Reception signal processing unit 510 Radio reception unit 512 Radio reception system 621 Averaging processing unit

Claims (6)

An array antenna type radio receiving apparatus that includes a plurality of antennas and a plurality of receiving means and performs communication using a multicarrier signal,
A reference signal generating means for generating a reference signal including at least one subcarrier signal having an orthogonal frequency relationship with respect to the multicarrier signal;
Signal multiplexing means for multiplexing the received signal and the reference signal;
An error that separates a reference signal that is multiplexed with a received signal that has passed through each of the plurality of receiving means, and compares the separated reference signals to calculate an error value of the received signal in each of the receiving means A calculation means;
Received signal processing means for correcting the received signal in each of the receiving means based on the error value of the received signal calculated by the error calculating means;
A radio receiving apparatus comprising:   And further comprising: line estimation means for transmitting channel fluctuation estimation information of the received signal to the reference signal generating means, and setting the frequency of the reference signal to the frequency of the subcarrier signal having a small received electric field strength. The wireless reception device according to 1.   Furthermore, an error correction value is calculated for each subcarrier signal based on a plurality of error values obtained by the error calculation means for a predetermined time, and an averaging process means for averaging the error correction values is provided. The wireless receiver according to claim 2, wherein: An array antenna type wireless transmission apparatus configured by a plurality of antennas and a plurality of transmission means and performing communication using a multicarrier signal,
A reference signal generating means for generating a reference signal including at least one subcarrier signal having an orthogonal frequency relationship with respect to the multicarrier signal;
Signal multiplexing means for multiplexing a transmission signal and the reference signal;
An error that separates a reference signal multiplexed into a transmission signal that has passed through each of the plurality of transmission means, and compares the separated reference signals to calculate an error value of the transmission signal in each of the transmission means A calculation means;
Transmission signal processing means for correcting the transmission signal in each of the transmission means based on the error value of the transmission signal calculated by the error calculation means;
A wireless transmission device comprising:   5. The radio transmission apparatus according to claim 4, wherein the signal multiplexing unit multiplexes the reference signal with a subcarrier signal not used for communication within the band of the transmission signal.   An averaging processing unit is provided that calculates an error correction value in each subcarrier signal based on a plurality of error values obtained in a predetermined time by the error calculation unit, and performs an averaging process of the error correction value. The wireless transmission device according to claim 5.

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