JP2008035364A - Receiving method, receiver using it, and radio apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct the frequency offset contained between signals received by a plurality of antennas. <P>SOLUTION: A reception weight vector calculator 68 derives a reception weight vector signal 312 every antenna unit and carrier unit from a plurality of received digital signals 300 over a training signal period. A sorter 50 sorts a plurality of multiplication signals 350 into one reference signal and the remains being signals under process. The reception weight vector calculator 68 generates a correction value per antenna unit so that the error of phase components of the signal under process from a phase component of the reference signal keeps a value in the training signal period even after this period and updates the reception weight vector signal 312 to deal with the signal under process every antenna unit and carrier unit, based on the correction value per antenna unit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reception technique, and more particularly, to a reception method for receiving a signal by a plurality of antennas, a reception apparatus and a radio apparatus using the reception method.

  In wireless communication, effective use of limited frequency resources is generally desired. One of the technologies for effectively using frequency resources is the adaptive array antenna technology. Adaptive array antenna technology forms the directivity pattern of an antenna by controlling the amplitude and phase of signals transmitted and received by a plurality of antennas. That is, a device equipped with an adaptive array antenna changes the amplitude and phase of signals received at a plurality of antennas, adds the changed reception signals, and changes the amplitude and phase (hereinafter referred to as the amount of change). And a signal equivalent to the signal received by the antenna having the directivity pattern corresponding to the “weight”. In addition, a signal is transmitted by an antenna directivity pattern corresponding to the weight.

  In the adaptive array antenna technique, an example of a process for calculating a weight is a method based on a minimum mean square error (MMSE) method. In the MMSE method, a Wiener solution is known as a condition for giving an optimum weight value, and a recurrence formula with a smaller amount of calculation than directly solving the Wiener solution is also known. As the recurrence formula, for example, an adaptive algorithm such as an RLS (Recursive Least Squares) algorithm or an LMS (Least Mean Squares) algorithm is used.

Even when the adaptive array antenna is not provided, a phase error called a normal frequency offset exists between the signal oscillated by the local oscillator included in the transmitter and the signal oscillated by the local oscillator included in the receiver. Due to the phase error, for example, when phase modulation such as QPSK (Quadrature Phase Shift Keying) is used for the modulation scheme between the transmission apparatus and the reception apparatus, the QPSK signal point on the constellation of the signal received by the reception apparatus rotates. . Such signal point rotation degrades the transmission quality of the signal. Usually, an AFC (Automatic Frequency Controller) for preventing this is provided in the receiving apparatus (see, for example, Patent Document 1).
JP 2001-285161 A

  In an adaptive algorithm or the like, generally, a weight is calculated in a known reference signal period, and a data signal following the reference signal is synthesized while being weighted by the weight. However, if a plurality of local oscillators are provided for each of the plurality of antennas constituting the adaptive array and the frequency stability of the plurality of local oscillators is low, the phase error between the plurality of signals generally passes over time. It grows with it. As a result, a plurality of signals that have been in-phase combined in the reference signal period may not be in-phase combined at the end of the data signal. When an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme is used, the composite gain is reduced due to such a phase error, so that the transmission quality of the signal is greatly reduced. In order to avoid such an increase in phase error, the weight may be adaptively updated even after the reference signal period has elapsed. However, the method of adaptively updating the weight generally increases the amount of calculation, leading to an increase in circuit scale and an increase in circuit price.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a reception technique for correcting a frequency offset included between signals received by a plurality of antennas.

  In order to solve the above problems, a receiving device according to an aspect of the present invention includes a receiving unit that receives a plurality of multicarrier signals each containing a known signal continuously in a predetermined period via a plurality of antennas. And a deriving unit for deriving a phase rotation signal for aligning phases in units of antennas and carriers for a plurality of multicarrier signals received by the receiving unit over a period in which at least known signals are included. When the plurality of multicarrier signals received at the receiving unit are phase-rotated in units of antennas and carriers by the phase rotation signal derived in step 1, one of the plurality of phase rotation results becomes a reference signal, and the plurality of phase rotations A means for performing classification so that the rest of the results are signals to be processed, and a reference signal and a signal to be processed are grouped by antenna unit. And an error of the phase component of the signal to be processed with respect to the phase component of the reference signal that has been phase-rotated in the synthesizing unit for each antenna after a period in which a known signal is included. Based on the error detection unit to detect and the error of the phase component of the antenna unit detected by the error detection unit, the phase rotation signal that should correspond to the signal to be processed is updated to the antenna unit and the carrier unit, and the updated phase rotation signal And an updating unit that outputs the information to the combining unit.

  In “synthesis”, only the phases of a plurality of signals may be synthesized, or the phases and amplitudes of a plurality of signals may be synthesized. According to this aspect, even after the period in which the known signal is included, the phase component of the signal to be processed is aligned with the phase component of the reference signal, so that the frequency offset can be corrected.

  Another embodiment of the present invention is also a receiving device. The apparatus includes a receiving unit that receives a plurality of multicarrier signals each containing a known signal continuously in a predetermined period via a plurality of antennas, and a plurality of multicarrier signals received by the receiving unit. An error of the phase component of the processing target signal with respect to the phase component of the reference signal selected by the classification unit that selects one of the plurality of signals as the reference signal and uses the rest of the plurality of signals as the processing target signal; The first generation for generating the correction value for each antenna so that the error detected for each antenna maintains the value in the period including the known signal even after the period including the known signal. Unit, a phase rotation unit that rotates the phase of the signal to be processed in units of antennas and carriers based on the correction value of the antenna unit generated in the first generation unit, and the reception unit. A second generation unit that generates a phase rotation signal for aligning the phases of a plurality of multicarrier signals in units of antennas and carriers over a period in which at least a known signal is included, and a phase rotation signal generated in the second generation unit And a combining unit that rotates the phase of the reference signal and the signal to be processed phase-rotated in the phase rotation unit in units of antennas and carriers, and combines the results in units of carriers.

  According to this aspect, even after the end of the period in which the known signal is included, the phase component of the signal to be processed is maintained so as to retain the phase error from the reference signal in the period in which the known signal is included. Since the rotation is performed, it is possible to correct the shift of the phase component that occurs after the period in which the known signal is included.

  Yet another embodiment of the present invention is also a receiving device. This device receives a plurality of multicarrier signals each containing a known signal continuously in a predetermined period via a plurality of antennas, and a plurality of multicarrier signals received by the receiving unit. The derivation unit for deriving the weighting factor in units of antennas and carriers over a period including at least a known signal, the weighting factor derived in the derivation unit, and a plurality of multicarrier signals received in the reception unit When performing multiplication while associating the antenna and the carrier, classification is performed so that one of the multiple multiplication results becomes the reference signal and the remaining of the multiple multiplication results becomes the signal to be processed. And a synthesizing unit including a unit for synthesizing a plurality of multiplication results for each carrier, and a phase component of the reference signal multiplied in the synthesizing unit A generation unit that generates a correction value for each antenna so that the error of the phase component of the signal to be processed maintains a value in a period in which the known signal is included even after the period in which the known signal is included; And an updating unit that updates the weighting factor to be processed corresponding to the signal to be processed to the antenna unit and the carrier unit, and outputs the updated weighting factor to the combining unit.

  According to this aspect, the weighting factor after the end of the period including the known signal is updated so as to maintain an error between a plurality of multiplication results in the period including the known signal. Even if it exists, it is possible to maintain a phase relationship in a period in which a known signal is included between multiplication results before synthesis.

  Yet another embodiment of the present invention is also a receiving device. This device receives a plurality of multicarrier signals each containing a known signal continuously in a predetermined period via a plurality of antennas, and a plurality of multicarrier signals received by the receiving unit. The derivation unit for deriving the weighting factor in units of antennas and carriers over a period including at least a known signal, the weighting factor derived in the derivation unit, and a plurality of multicarrier signals received in the reception unit When performing multiplication while associating the antenna and the carrier, classification is performed so that one of the multiple multiplication results becomes the reference signal and the remaining of the multiple multiplication results becomes the signal to be processed. And a synthesizing unit including a unit for synthesizing a plurality of multiplication results for each carrier, and a phase component of the reference signal multiplied in the synthesizing unit A generation unit that generates a correction value for each antenna so that the error of the phase component of the signal to be processed maintains a value in a period in which the known signal is included even after the period in which the known signal is included; The update unit that updates the weighting factor to be processed corresponding to the signal to be processed to the antenna unit and the carrier unit, and outputs the updated weighting factor to the synthesizing unit, and the multi-synthesizer synthesized by the synthesizing unit And a demodulator that demodulates the carrier signal.

  The receiving unit may receive a plurality of multicarrier signals by local signals output from local oscillators respectively corresponding to the plurality of antennas. In this case, the frequency offset can be corrected even when reception is performed by local signals output from a plurality of local oscillators.

  You may further provide the measurement part which each measures the intensity | strength of the several multicarrier signal received in the receiving part. The combining unit may determine the reference signal according to the intensity measured by the measuring unit. In this case, since the reference signal is determined according to the intensity of the signal, the reliability of selection of the reference signal can be improved.

  Yet another embodiment of the present invention is a wireless device. The apparatus includes a plurality of antennas, a reception unit that receives a plurality of multicarrier signals each including a known signal continuously in a predetermined period via the plurality of antennas, and a plurality of reception units received by the reception unit. For a multicarrier signal, at least over a period in which a known signal is included, a deriving unit for deriving a weighting factor in units of antennas and carriers, a weighting factor derived in the deriving unit, and a plurality of multi-signals received in the receiving unit When performing multiplication on the carrier signal while associating the antenna and the carrier, one of a plurality of multiplication results becomes a reference signal, and the remainder of the plurality of multiplication results becomes a signal to be processed. And a combining unit including a unit for performing classification and a unit for combining a plurality of multiplication results in units of carriers, and a reference signal multiplied in the combining unit. Generation of a correction value for each antenna so that the error of the phase component of the signal to be processed with respect to the phase component of the signal maintains the value in the period including the known signal even after the period including the known signal An update unit that updates the weighting factor to be processed corresponding to the signal to be processed to the antenna unit and the carrier unit, and outputs the updated weighting factor to the combining unit, according to the correction value for the antenna unit generated in the generating unit, and the combining unit And a demodulator for demodulating the multi-carrier signal synthesized in the above.

  Yet another embodiment of the present invention is a reception method. In this method, a plurality of multicarrier signals each including a known signal continuously included in a predetermined period are received via a plurality of antennas, and at least the plurality of received multicarrier signals are known. The step of deriving the weighting factor in units of antennas and carriers over the period including the signal of, and multiplying the derived weighting factor by a plurality of received multicarrier signals while associating the antenna and the carrier And executing the classification on the phase component of the reference signal so that one of the multiple multiplication results becomes the reference signal and the remaining of the multiple multiplication results becomes the signal to be processed. The error of the phase component of the target signal is maintained in the period including the known signal even after the period including the known signal. Comprising the steps of generating a positive value to the antenna unit, by the correction value of the generated antenna unit, and updating the weighting coefficients to be corresponding to the processing target signal to the antenna unit and the carrier unit, the.

  Yet another embodiment of the present invention is also a reception method. In this method, a plurality of multicarrier signals each including a known signal continuously included in a predetermined period are received via a plurality of antennas, and at least the plurality of received multicarrier signals are known. And a step of deriving a phase rotation signal for aligning the phase in units of antennas and carriers over a period including the signal of the signal and a plurality of received multicarrier signals in units of antennas and carriers by the derived phase rotation signal. When performing phase rotation, a step of performing classification so that one of the plurality of phase rotation results becomes a reference signal and the remaining of the plurality of phase rotation results becomes a processing target signal, and a phase-rotated reference The error of the phase component of the signal to be processed with respect to the phase component of the signal Comprising detecting, based on the error of the phase component of the detected antenna unit, and updating the phase rotation signal should correspond to the processed signal to the antenna unit and the carrier unit, to.

  Yet another embodiment of the present invention is also a reception method. In this method, a step of receiving a plurality of multicarrier signals each including a known signal continuously included in a predetermined period via a plurality of antennas, and a plurality of signals among the plurality of received multicarrier signals. One of the signals is selected as a reference signal, the remainder of the plurality of signals is set as a signal to be processed, and an error in the phase component of the signal to be processed with respect to the phase component of the selected reference signal is detected for each antenna. The step of generating the correction value for each antenna so that the error remains in the period including the known signal even after the period including the known signal, and the generated correction value for each antenna , Phase-rotating the signal to be processed in units of antennas and carriers, and a phase rotation signal for aligning the phases of the received multi-carrier signals A step of generating at least an antenna unit and a carrier unit over a period including a known signal, and a phase-rotated processing target signal and a reference signal are phase-rotated to the antenna unit and the carrier unit by the generated phase rotation signal; Synthesizing the results in carrier units.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to correct a frequency offset included between signals received by a plurality of antennas.

  Before describing the present invention in detail, an outline will be described. An embodiment of the present invention relates to a base station apparatus to which a terminal apparatus can be connected, such as a base station apparatus used in a communication system such as a wireless LAN (Local Area Network). Note that an OFDM modulation scheme is used in the communication system. The base station apparatus according to the embodiment of the present invention includes a plurality of antennas, and further includes a local oscillator corresponding to each of the plurality of antennas. The base station apparatus receives the received multicarrier signal from the terminal apparatus to be communicated using a plurality of antennas, and orthogonally detects the received multicarrier signal with a local oscillator. Further, the base station apparatus calculates a weighting factor for each antenna and carrier from a plurality of quadrature-detected multicarrier signals (hereinafter referred to as a general term for the calculated weighting factor or a group of weighting factors for each carrier as “reception weight”. Vector ", but the distinction between the two is not specified).

  Based on the calculated reception weight vector, the base station apparatus performs adaptive array signal processing on the received multicarrier signal. The multicarrier signal from the terminal device constitutes a packet signal. A known signal is arranged at the head portion of the packet signal, and a data signal is arranged following the known signal. The base station apparatus calculates a reception weight vector in a period in which a known signal among the received packet signals is included. Since the local oscillators are not high in frequency stability, the respective frequencies are shifted from each other. As a result, phase errors occur between the plurality of received signals in the data signal period.

  The base station apparatus according to the embodiment of the present invention selects a signal having the highest received power among a plurality of multicarrier signals received by a plurality of antennas (hereinafter referred to as “reference signal”), and processes other signals. Signal. During a known signal period, the phase of the reception weight vector corresponding to the reference signal (hereinafter referred to as “reference reception weight vector”) and the reception weight vector corresponding to the processing target signal (hereinafter referred to as “processing target reception weight vector”) Derived. In the data signal period, the multiplication result of the reference signal and the reference reception weight vector (hereinafter also referred to as “reference signal”, but used without distinction from the above-mentioned reference signal), the signal to be processed, A phase error is calculated for each antenna unit between the result of multiplication with the processing target reception weight vector (hereinafter also referred to as “processing target signal”, but used without distinction from the processing target signal described above).

  Further, the base station apparatus derives a correction value for each antenna so that the phase error in the data signal period maintains the known signal period, and the reference reception weight vector and the processing target reception are determined based on the correction value. Update the weight vector. That is, control is performed such that the phase relationship between the reference reception weight vector and the processing target reception weight vector after the end of the known signal period is close to the phase relationship at the end of the known signal period.

  FIG. 1 shows a spectrum of a multicarrier signal according to an embodiment of the present invention. In particular, FIG. 1 shows the spectrum of a signal in the OFDM modulation scheme. One of a plurality of carriers in the OFDM modulation system is generally called a subcarrier, but here, one subcarrier is designated by a “subcarrier number”. For example, in a communication system compliant with the IEEE 802.11n standard (hereinafter referred to as “MIMO system”), 56 subcarriers from subcarrier numbers “−28” to “28” are defined. The subcarrier number “0” is set to null in order to reduce the influence of the DC component in the baseband signal. On the other hand, in a system that does not support the MIMO system (hereinafter referred to as “conventional system”), 52 subcarriers from subcarrier numbers “−26” to “26” are defined. An example of a conventional system is a wireless LAN compliant with the IEEE 802.11a standard.

  Further, one signal unit composed of a plurality of subcarriers and one signal unit in the time domain is referred to as an “OFDM symbol”. Each subcarrier is modulated by a variably set modulation scheme. As the modulation method, any one of BPSK (Binary Phase Shift Keying), QSPK, 16QAM (Quadrature Amplitude Modulation), and 64QAM is used.

  FIG. 2 shows a configuration of the communication system 100 according to the embodiment of the present invention. The communication system 100 includes a terminal device 10, a base station device 34, and a network 32. The terminal device 10 includes a baseband unit 26, a modem unit 28, a radio unit 30, and a terminal antenna 16, and the base station device 34 includes a first base station antenna 14a, a second base station antenna 14a, and a second base station antenna 14. Base station antenna 14b, Nth base station antenna 14n, first radio unit 12a, second radio unit 12b, Nth radio unit 12n, signal processing unit 18, modem unit 20, baseband Part 22 and control part 24. In addition, as a signal, a first digital reception signal 300a, a second digital reception signal 300b, an Nth digital reception signal 300n, which are collectively referred to as a digital reception signal 300, a first digital transmission signal 302a, which is collectively referred to as a digital transmission signal 302, 2 digital transmission signal 302b, Nth digital transmission signal 302n, composite signal 304, pre-separation signal 308, signal processing unit control signal 310, and radio unit control signal 318.

  The terminal device 10 is connected to the base station device 34 and performs communication with the base station device 34. The baseband unit 26 is an interface with a PC connected to the terminal device 10 and an application inside the terminal device 10, and performs transmission / reception processing of an information signal to be transmitted in the communication system 100. Further, error correction and automatic retransmission processing may be performed, but the description thereof is omitted here. The modem unit 28 generates a transmission signal by executing mapping to BPSK or the like, IFFT (Inverse Fast Fourier Transform), and orthogonal modulation as transmission processing. On the other hand, the modem unit 28 reproduces the information signal transmitted from the base station apparatus 34 by executing quadrature detection, FFT, and demodulation as reception processing. Here, the signal output from the modem unit 28 in the transmission process and the signal input to the modem unit 28 in the reception process form a multicarrier signal like an OFDM signal. In addition, the multicarrier signal constitutes a packet signal. The radio unit 30 executes frequency conversion processing. The wireless unit 30 performs amplification processing, AD or DA conversion processing, and the like. The radio unit 30 transmits and receives radio frequency signals to and from the base station apparatus 34 via the terminal antenna 16.

  A plurality of base station antennas 14 are provided. Here, the number of base station antennas 14 is N. As a reception operation, the radio unit 12 performs frequency conversion on a radio frequency multicarrier signal received by the base station antenna 14 and derives a baseband signal. As described above, the multicarrier signal constitutes a packet signal, and a known signal (hereinafter referred to as “training signal”) is continuously included in the head portion of the packet signal. Each of the plurality of radio units 12 includes a local oscillator corresponding to each of the plurality of base station antennas 14, and the radio unit 12 receives a plurality of multicarrier signals by a local signal output from the local oscillator. Each frequency is converted.

  The radio unit 12 outputs the baseband signal to the signal processing unit 18 as a digital reception signal 300. In general, baseband signals are formed by in-phase and quadrature components, so they should be transmitted by two signal lines. Here, for clarity of illustration, only one signal line is used. Shall be shown. The wireless unit 12 also includes an AGC (Automatic Gain Control) and an A / D conversion unit.

  As a transmission operation, the radio unit 12 performs frequency conversion on the baseband signal from the signal processing unit 18 to derive a radio frequency signal. Here, the baseband signal from the signal processing unit 18 is shown as a digital transmission signal 302. The radio unit 12 outputs a radio frequency signal to the base station antenna 14. That is, the radio unit 12 transmits a radio frequency packet signal from the base station antenna 14. Further, a PA (Power Amplifier) and a D / A converter are also included. The digital transmission signal 302 is a multicarrier signal converted into the time domain, and is a digital signal.

  As a reception operation, the signal processing unit 18 converts each of the plurality of digital reception signals 300 into the frequency domain, and performs adaptive array signal processing on the frequency domain signal. The signal processing unit 18 outputs the result of adaptive array signal processing as a synthesized signal 304. Further, as a transmission operation, the signal processing unit 18 inputs a pre-separation signal 308 as a frequency domain signal from the modem unit 20, converts the frequency domain signal to the time domain, and transmits a plurality of base station antennas 14. The digital transmission signal 302 is output while being associated with each. Here, the combined signal 304 and the pre-separation signal 308, which are frequency domain signals, include a plurality of subcarrier components as shown in FIG. For the sake of clarity, it is assumed that the frequency domain signals are arranged in the order of subcarrier numbers to form a serial signal.

  FIG. 3 shows the structure of a signal in the frequency domain. Here, one combination of subcarrier numbers “−28” to “28” shown in FIG. 1 is referred to as an “OFDM symbol”. In the “i” th OFDM symbol, subcarrier components are arranged in the order of subcarrier numbers “1” to “28” and subcarrier numbers “−28” to “−1”. Also, the “i−1” th OFDM symbol is arranged before the “i” th OFDM symbol, and the “i + 1” th OFDM symbol is arranged after the “i” th OFDM symbol. And In the conventional system, a combination of subcarrier numbers “−26” to “26” is used for one “OFDM symbol”. Returning to FIG.

  The reception process in the signal processing unit 18 will be described in more detail. The signal processing unit 18 derives reception weight vectors for the plurality of digital reception signals 300 over the training signal period of the packet signal. The reception weight vector has base station antenna 14 units and subcarrier unit components. The base station antenna 14 of the base station antenna 14 unit corresponds to the base station antenna 14 that has received the digital reception signal 300. Further, the signal processing unit 18 performs multiplication on the reception weight vector and the digital reception signal 300 while associating the base station antenna 14 with the subcarrier. At that time, the signal processing unit 18 performs classification so that one of a plurality of multiplication results in one subcarrier becomes a reference signal, and the rest of the plurality of multiplication results becomes a signal to be processed. As a result, the reception weight vector is also classified into the reference reception weight vector and the processing target reception weight vector as described above. A plurality of multiplication results are combined in units of subcarriers, and the combined result corresponds to the above-described combined signal 304.

  Further, the signal processing unit 18 sets the correction value so that the error of the phase component of the processing target signal with respect to the phase component of the reference signal maintains a value in the training signal period after the training signal period. To generate. Specifically, the error of the phase component of the signal to be processed with respect to the phase component of the reference signal is derived for each base station antenna 14 unit and subcarrier unit, and the derived error is combined for each base station antenna 14 unit. Thus, a correction value for each base station antenna 14 is derived. Note that combining the base station antenna 14 units corresponds to combining a plurality of errors corresponding to the same antenna. Thereafter, the signal processing unit 18 updates the processing target reception weight vector to the base station antenna 14 unit and the subcarrier unit with the generated correction value of the base station antenna 14 unit, and the updated processing target reception weight vector is digitally updated. Used for multiplication with the received signal 300. That is, the correction value for each base station antenna 14 is used to update the processing target reception weight vector corresponding to the base station antenna 14.

  When the signal processing unit 18 ideally executes the maximum ratio combining process, the error of the phase component of the processing target signal with respect to the phase component of the reference signal becomes “0” at the end of the training signal period. Here, for the sake of clarity, a configuration for holding the phase error at “0” after the end of the training signal period is shown. When there is little time fluctuation of the wireless transmission path and only a frequency offset difference between the local oscillators 166 provided for each of the plurality of base station antennas 14 exists, simple rotation of the reception weight vector with respect to the signal to be processed Only may be made.

  The modem unit 20 performs demodulation and deinterleaving on the combined signal 304 from the signal processing unit 18 as reception processing. Note that demodulation is performed in units of subcarriers. The modem unit 20 outputs the demodulated signal to the baseband unit 22. Further, the modem unit 20 executes interleaving and modulation as transmission processing. The modem unit 20 outputs the modulated signal to the signal processing unit 18 as a pre-separation signal 308. It is assumed that the modulation method is designated by the control unit 24 during the transmission process. The baseband unit 22 is an interface between a signal to be processed in the base station device 34 and the network 32. The control unit 24 controls the timing of the base station device 34 and the like.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it is realized by a program having a communication function loaded in the memory. Describes functional blocks realized by collaboration. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 4 shows the structure of the first radio unit 12a. The first radio unit 12a includes a switch unit 140, a reception unit 142, a transmission unit 144, and a local oscillation unit 166. Further, the reception unit 142 includes a frequency conversion unit 146, an AGC 148, a quadrature detection unit 150, and an AD conversion unit 152. The transmission unit 144 includes an amplification unit 164, a frequency conversion unit 156, a quadrature modulation unit 158, and a DA conversion unit 160. Including.

  The switch unit 140 switches input / output of signals to / from the reception unit 142 and the transmission unit 144 based on a radio unit control signal 318 from the control unit 24 (not shown). That is, a signal from the transmission unit 144 is selected at the time of transmission, and a signal to the reception unit 142 is selected at the time of reception. The frequency conversion unit 146 of the reception unit 142 and the frequency conversion unit 156 of the transmission unit 144 perform frequency conversion between the radio frequency and the intermediate frequency on the target signal.

  The AGC 148 automatically controls the gain so that the amplitude of the received signal becomes an amplitude within the dynamic range of the AD conversion unit 152. The quadrature detection unit 150 performs quadrature detection on the intermediate frequency signal to generate a baseband analog signal. On the other hand, the quadrature modulation unit 158 quadrature modulates the baseband analog signal to generate an intermediate frequency signal.

  The local oscillation unit 166 supplies a local signal having a predetermined frequency to the quadrature detection unit 150 and the quadrature modulation unit 158. As shown in the figure, since one local oscillation unit 166 is provided for one radio unit 12, a plurality of local oscillation units 166 are provided for the plurality of radio units 12. The AD converter 152 converts a baseband analog signal into a digital signal, and the DA converter 160 converts the baseband digital signal into an analog signal. The amplifying unit 164 amplifies a radio frequency signal to be transmitted.

  FIG. 5 shows the configuration of the signal processing unit 18. The signal processing unit 18 includes a first FFT unit 40a, a second FFT unit 40b, an NFFT unit 40n, a classification unit 50, a synthesis unit 60, a reception weight vector calculation unit 68, a reference signal storage unit 70, a measurement, which are collectively referred to as an FFT unit 40. Section 200, separation section 72, transmission weight vector calculation section 76, first IFFT section 42a, second IFFT section 42b, and NIFFT section 42n collectively referred to as IFFT section 42. The synthesizing unit 60 includes a first multiplying unit 62a, a second multiplying unit 62b, an Nth multiplying unit 62n, and an adding unit 64, which are collectively referred to as a multiplying unit 62, and the separating unit 72 is collectively referred to as a multiplying unit 74. A first multiplier 74a, a second multiplier 74b, and an Nth multiplier 74n are included.

  As signals, a reference signal 306, an output reception weight vector signal 402, a first reception weight vector signal 312a, a second reception weight vector signal 312b, which is collectively referred to as a reception weight vector signal 312, an Nth reception weight vector signal 312n, and a transmission weight. A first transmission weight vector signal 314a, a second transmission weight vector signal 314b, an Nth transmission weight vector signal 314n, collectively referred to as a vector signal 314, a first multiplication signal 350a, a second multiplication signal 350b, collectively referred to as a multiplication signal 350, An Nth multiplication signal 350n and a reference notification signal 352 are included.

  The FFT unit 40 performs FFT on the input digital reception signal 300. That is, the FFT unit 40 converts a time domain signal into a frequency domain signal. Here, the signal converted into the frequency domain is also referred to as a digital received signal 300. Also, the digital received signal 300 converted into the frequency domain is configured as shown in FIG.

  The measurement unit 200 measures the reception power of each of the plurality of digital reception signals 300 during the training signal period, and selects one of the digital reception signals 300 having the highest reception power as a reference signal. As described above, the digital reception signal 300 other than the reference signal is set as the processing target signal. That is, the measurement unit 200 determines the reference signal according to the measured signal strength. Here, the digital reception signal 300 is formed by a plurality of subcarriers as shown in FIG. 1, but the measurement unit 200 calculates the total reception power of a plurality of subcarriers as reception power for one digital reception signal 300. Measure the value. Information regarding the selected reference signal is output as a reference notification signal 352. Here, the recognition during the training signal period is performed by the signal processing unit control signal 310.

  The classification unit 50 performs classification on the digital reception signal 300 by changing the order of the digital reception signal 300 based on the reference notification signal 352 after the training signal period ends. Specifically, a digital reception signal 300 to be a reference signal is input to the first multiplication unit 62a in the later-described multiplication unit 62. On the other hand, during the training signal period, the classification unit 50 may not replace the input digital reception signal 300 or may replace the order of the digital reception signal 300 based on the reference notification signal 352 in the previous burst signal. Good. Here, the classification is performed on the digital received signal 300 of the base station antenna 14 unit.

  The combiner 60 weights the digital reception signal 300 with the reception weight vector signal 312 in the base station antenna 14 unit and the subcarrier unit in the multiplication unit 62 to generate the multiplication signal 350, and then adds the multiplication signal 350 to the addition unit The result is added at 64, and the combined signal 304 is output. The first reception weight vector signal 312a input to the first multiplication unit 62a corresponds to the above-described reference reception weight vector, and the other reception weight vector signals 312 correspond to the above-described target processing reception weight vector. . The first multiplication signal 350a output from the first multiplication unit 62a corresponds to a reference signal, and the other multiplication signals 350 correspond to target processing signals. Note that multiplication in one multiplication unit 62 is performed for each subcarrier as shown in FIG. The reference signal storage unit 70 outputs a known training signal stored in advance during the training signal period as a reference signal 306.

  The reception weight vector calculation unit 68 converts the reception weight vector signal 312 from the digital reception signal 300, the synthesized signal 304, and the reference signal 306 over the training signal period by an adaptive algorithm such as an RLS algorithm or an LMS algorithm for each base station antenna 14 unit. And calculated in units of subcarriers. On the other hand, after the end of the training signal period, the reception weight vector signal 312 is updated based on the multiplication signal 350. Details of the update method will be described later.

  Based on output reception weight vector signal 402, transmission weight vector calculation unit 76 derives transmission weight vector signal 314 necessary for weighting pre-separation signal 308 in units of base station antennas 14 and subcarriers. In order to simplify the processing, the reception weight vector signal 312 and the transmission weight vector signal 314 may be the same. Separation section 72 weights pre-separation signal 308 by base station antenna 14 unit and subcarrier unit by transmission weight vector signal 314 in multiplication section 74 and outputs the result as digital transmission signal 302. The IFFT unit 42 performs IFFT on the digital transmission signal 302 from the multiplication unit 74. That is, the IFFT unit 42 converts a frequency domain signal into a time domain signal. Here, the signal converted into the time domain is also referred to as a digital transmission signal 302.

  FIG. 6 shows the configuration of the reception weight vector calculation unit 68. The reception weight vector calculation unit 68 includes a reception weight vector update unit 114, an output setting unit 116, a classification unit 118, and an initial weight vector calculation unit 120. Also, as signals, a first initial weight vector signal 362a, a second initial weight vector signal 362b, an Nth initial weight vector signal 362n, collectively referred to as an initial weight vector signal 362, and a first output, collectively referred to as an output received weight vector signal 402. A received weight vector signal 402a, a second output received weight vector signal 402b, and an Nth output received weight vector signal 402n are included.

  The initial weight vector calculation unit 120 calculates the initial weight vector signal 362 from the digital reception signal 300, the synthesized signal 304, and the reference signal 306 in units of the base station antenna 14 and the subcarrier by the above-described adaptive algorithm during the training signal period. To do. In the training signal period, the initial weight vector signal 362 is output as a received weight vector signal 312 to the synthesizer 60 (not shown).

  At the end of the training signal period, the classification unit 118 selects an initial weight vector signal 362 (hereinafter referred to as “reference initial weight for reference) from the initial weight vector signal 362 according to the content of the reference notification signal 352. The initial weight vector signal 362 corresponding to the signal to be processed is referred to as “initial weight vector for processing”). Further, the classification unit 118 outputs the reference initial weight vector to the reception weight vector update unit 114 as the first initial weight vector signal 362a. Further, the classification unit 118 outputs the processing target initial weight vector from the second initial weight vector signal 362b to the Nth initial weight vector signal 362n to the reception weight vector update unit 114.

  The reception weight vector update unit 114 updates the reception weight vector signal 312 for each base station antenna 14 unit with the initial weight vector signal 362 as an initial value after the end of the training signal period. That is, the plurality of reception weight vector signals 312 corresponding to the same base station antenna 14 are updated with the same correction value. Through such processing, the reception weight vector updating unit 114 receives the reception weight so that the phase difference of the signal to be processed with respect to the phase difference of the reference signal in the multiplication signal 350 maintains the value when the training signal period ends. The vector signal 312 is updated.

  The output setting unit 116 outputs the reception weight vector signal 312 as the output reception weight vector signal 402. The output setting unit 116 may continuously output the output reception weight vector signal 402, or the output reception weight vector signal 402 at a specific time point, such as the reception weight vector signal 312 when the packet signal ends. May be output.

  FIG. 7 shows the configuration of the initial weight vector calculation unit 120. The initial weight vector calculator 120 includes a first initial weight vector calculator 120a, a second initial weight vector calculator 120b, and an Nth initial weight vector calculator 120n. The first initial weight vector calculator 120a includes an adder 80. , A complex conjugate unit 82, a multiplication unit 84, a step size parameter storage unit 86, a multiplication unit 88, an addition unit 90, and a delay unit 92. The second initial weight vector calculation unit 120b to the Nth initial weight vector calculation unit 120n are configured in the same manner as the first initial weight vector calculation unit 120a.

  The adder 80 calculates a difference between the synthesized signal 304 and the reference signal 306, and outputs this as an error signal. This error signal is subjected to complex conjugate conversion by the complex conjugate unit 82. The multiplier 84 multiplies the error signal that has been subjected to the complex conjugate transformation by the first digital reception signal 300a to generate a first multiplication result.

  The multiplication unit 88 multiplies the first multiplication result by the step size parameter stored in the step size parameter storage unit 86 to generate a second multiplication result. The second multiplication result is fed back by the delay unit 92 and the addition unit 90, and then added to the new second multiplication result. The addition result sequentially updated by the LMS algorithm is output as the first reception weight vector signal 312a. The above processing is performed for each subcarrier.

  FIG. 8 shows the configuration of the reception weight vector update unit 114. The reception weight vector update unit 114 is collectively referred to as a first multiplication unit 122a, an N−1th multiplication unit 122 (n−1), an inter-signal error detection unit 124, a generation unit 126, and a holding unit 128, which are collectively referred to as a multiplication unit 122. The first holding unit 128a, the second holding unit 128b, and the Nth holding unit 128n.

  The inter-signal error detection unit 124 calculates the phase error of the processing target signal with respect to the reference signal. That is, with respect to the phase error of the first multiplication signal 350a, the phase error of the second multiplication signal 350b to the Nth multiplication signal 350n is calculated for each base station antenna 14. Here, the calculation of the phase error for each base station antenna 14 is performed after the phase error is derived for each subcarrier for the multiplication signal 350 corresponding to one base station antenna 14. Is derived by The calculation of the phase error may be performed by calculating the phase value or by vector calculation.

  The generation unit 126 generates a correction value for each base station antenna 14 from the phase error value for each base station antenna 14 calculated by the inter-signal error detection unit 124. Specifically, the correction value is generated so that the phase corresponding to the phase error value rotates in the reverse direction. For example, if the value of the phase error is “x °”, the correction value is “−x °”.

  The multiplication unit 122 updates the past received weight vector signal 312 stored in the holding unit 128 with the correction value output from the generation unit 126, and outputs a new received weight vector signal 312. A reception weight vector signal 312 to be processed by the multiplier 122 is a processing target reception weight vector. Here, similarly to the inter-signal error detection unit 124, the calculation by the multiplication unit 122 may be executed by the calculation of the phase value or may be executed by the vector calculation. In the case of executing the calculation by the phase value, it is necessary to separately store the amplitude value.

  The holding unit 128 holds the initial weight vector signal 362 when the training signal period ends, and holds the reception weight vector signal 312 updated in the multiplication unit 122 after the training signal period ends. Here, as described above, the reference initial weight vector is the first initial weight vector signal 362a.

  FIG. 9 shows the configuration of the inter-signal error detection unit 124. The inter-signal error detection unit 124 includes a complex conjugate unit 250, a first multiplication unit 252a collectively referred to as a multiplication unit 252, an N-1th multiplication unit 252n-1, a first integration unit 254a collectively referred to as an integration unit 254, and a first integration unit 254a. N-1 integrating part 254n-1 is included.

  The complex conjugate unit 250 receives the first multiplication signal 350a and derives a complex conjugate. This corresponds to deriving a complex conjugate of the reference signal. When first multiplication signal 350a is shown as a phase value instead of a vector value, complex conjugate section 250 inverts the sign of first multiplication signal 350a. The multiplier 252 multiplies the reference signal from which the complex conjugate is derived and the processing target signal. This multiplication corresponds to deriving a phase error between the reference signal and the signal to be processed. For example, the first multiplication unit 252a derives an error of the phase component of the second multiplication signal 350b with respect to the phase component of the first multiplication signal 350a. Multiplication in the multiplication unit 252 is executed in the order of subcarrier numbers shown in FIG.

The accumulating unit 254 accumulates the multiplication results of the multiplying unit 252 over a plurality of subcarriers. That is, the accumulating unit 254 accumulates the phase error between the reference signal and the processing target signal over one OFDM symbol period. Integration by the integration unit 254 is performed when the multiplication signal 350 is indicated by a vector value. When the multiplication signal 350 is indicated by a phase value, the integration unit 254 executes an averaging process. By such processing, the accumulating unit 254 derives a phase error for each antenna. This is equivalent to averaging of phase errors in a plurality of subcarriers as in one OFDM symbol, so that the influence of noise can be reduced. . The processing in the integration unit 254 is shown as follows.

  Here, Eij is a phase error corresponding to the I-base station antenna 14i and the subcarrier number j, and is shown as a vector value. Δθi is an integrated value of the phase error corresponding to the antenna for the first base station 14i. Δθi is shown as a phase value, but may be a vector value. The generation unit 126 (not shown) receives Δθi and derives −Δθi as a correction value. When Δθi is a vector value, the generation unit 126 may derive a complex conjugate.

  The operation of the base station apparatus 34 having the above configuration will be described. FIG. 10 is a flowchart showing the procedure for updating the weight vector. When the received multicarrier signal is in the training signal period (Y in S10), the initial weight vector calculation unit 120 calculates the initial weight vector signal 362 (S12). The initial weight vector signal 362 is composed of base station antenna 14 units and subcarrier unit components. At the end of the training signal period, the classification unit 50 executes the classification based on the reference notification signal 352, and the classification unit 118 also uses the initial weight vector signal 362 as the reference initial signal based on the reference notification signal 352. Classification into weight vectors and initial weight vectors for processing (S14).

  On the other hand, if it is not the training signal period (N of S10), the reception weight vector update unit 114 detects the phase error of the signal to be processed with respect to the reference signal in the multiplication signal 350 for each base station antenna 14 (S18). . Also, the reception weight vector update unit 114 derives a correction value from the detected phase error (S20). Further, the reception weight vector update unit 114 updates the reception weight vector signal 312 with the correction value (S22).

  The operation of the base station apparatus 34 will be described more specifically. The multicarrier signals received by the base station antenna 14 are orthogonally detected by the local oscillators 166 having different frequency offsets. The quadrature-detected multicarrier signal is digitally converted into a digital reception signal 300. In the training signal period of the received packet signal, the initial weight vector calculation unit 120 calculates the initial weight vector signal 362 for each base station antenna 14 and each subcarrier based on the adaptive algorithm. In addition, the measurement unit 200 measures the power of the digital reception signal 300 for each base station antenna 14 and controls so that the digital reception signal 300 having the largest power becomes the reference signal.

  After the end of the training signal period, the reception weight vector updating unit 114 determines the phase error of the signal to be processed with respect to the reference signal in the multiplication signal 350 obtained by multiplying the reception weight vector signal 312 and the digital reception signal 300 by the base station antenna. Calculate to 14 units. Further, reception weight vector update section 114 derives a correction value for each base station antenna 14 from the calculated phase error value, and updates reception weight vector signal 312 with the correction value. Further, the adder 64 synthesizes the multiplication signal 350 and outputs a synthesized signal 304.

  The above description has been made assuming that the communication system 100 is a conventional system. However, the communication system 100 may be a MIMO system instead of a conventional system. Since the packet signal in the MIMO system is composed of a plurality of sequences, the terminal apparatus 10 includes a plurality of terminal antennas 16, a plurality of radio units 30, and a plurality of modem units 28 in order to cope with it. The base station apparatus 34 includes a plurality of signal processing units 18 and a plurality of modem units 20. In such a configuration, the terminal apparatus 10 and the base station apparatus 34 process a plurality of sequences in parallel. Here, the packet signal when the MIMO system is applied will be described.

  Fig.11 (a)-(c) shows the format of a packet signal. Here, FIG. 11A corresponds to the case where the number of series is “4”, and FIG. 11B corresponds to the case where the number of series is “3”. Corresponds to the case where the number of series is “2”. In FIG. 11A, it is assumed that data included in the four sequences is to be transmitted, and packet formats corresponding to the first to fourth sequences are shown in order from the top to the bottom.

  In the packet signal corresponding to the first stream, “L-STF”, “HT-LTF”, and the like are arranged as preamble signals. “L-STF”, “L-LTF”, “L-SIG”, “HT-SIG” are known signals for AGC setting, known signals for transmission path estimation, control signals, MIMO systems corresponding to conventional systems Correspond to the control signals corresponding to. The control signal corresponding to the MIMO system includes, for example, information on the number of sequences and the destination of the data signal. “HT-STF” and “HT-LTF” correspond to a known signal for AGC setting and a known signal for channel estimation corresponding to the MIMO system. The training signal described above corresponds to any one of “L-STF”, “HT-LTF”, “HT-STF”, “HT-LTF”, or any combination. On the other hand, “data 1” is a data signal. Note that L-LTF and HT-LTF are used not only for AGC setting but also for timing estimation.

  Also, in the packet signal corresponding to the second stream, “L-STF (−50 ns)”, “HT-LTF (−400 ns)” and the like are arranged as preamble signals. Further, in the packet signal corresponding to the third stream, “L-STF (−100 ns)”, “HT-LTF (−200 ns)”, and the like are arranged as preamble signals. In the packet signal corresponding to the fourth stream, “L-STF (−150 ns)”, “HT-LTF (−600 ns)”, and the like are arranged as preamble signals.

  Here, “−400 ns” or the like indicates a timing shift amount in CDD (Cyclic Delay Diversity). CDD is a process in which a waveform in the time domain is shifted backward by a shift amount in a predetermined period, and the waveform pushed out from the last part of the predetermined period is cyclically arranged at the head part of the predetermined period. That is, “L-STF (−50 ns)” is cyclically shifted with a delay amount of −50 ns with respect to “L-STF”. Note that L-STF and HT-STF are configured by repetition of a period of 800 ns, and other HT-LTFs and the like are configured by repetition of a period of 3.2 μs. Here, “data 1” to “data 4” are also CDDed, and the timing shift amount is the same value as the timing shift amount in the HT-LTF arranged in the preceding stage.

  In the first stream, HT-LTFs are arranged in the order of “HT-LTF”, “−HT-LTF”, “HT-LFT”, and “−HT-LTF” from the top. Here, these are sequentially referred to as “first component”, “second component”, “third component”, and “fourth component” in all series. If the calculation of the first component-second component + third component-fourth component is performed on all series of received signals, the receiving apparatus extracts a desired signal for the first series. Further, if the calculation of the first component + second component + third component + fourth component is performed on all series of received signals, the receiving apparatus extracts a desired signal for the second series. Further, if the calculation of the first component-second component-third component + fourth component is performed on all series of received signals, the receiving apparatus extracts a desired signal for the third series. Also, if the calculation of the first component + second component−third component−fourth component is performed on the received signals of all sequences, the desired signal for the fourth sequence is extracted in the receiving apparatus. These correspond to the combination of codes of predetermined components having an orthogonal relationship between sequences. The addition / subtraction process is executed by vector calculation.

  In the part from “L-LTF” to “HT-SIG” and the like, “52” subcarriers are used as in the conventional system. Of the “52” subcarriers, “4” subcarriers correspond to pilot signals. On the other hand, “56” subcarriers are used in the subsequent parts such as “HT-LTF”.

  In FIG. 11A, the sign of “HT-LTF” is defined as follows. The codes are arranged in the order of “+”, “−”, “+”, “−” in order from the top of the first sequence, and the codes are “+”, “+”, “+” in order from the top of the second sequence. Arranged in the order of “+” and “+”, the codes are arranged in the order of “+”, “−”, “−” and “+” in order from the top of the third series, and from the top of the fourth series. In order, the codes are arranged in the order of “+”, “+”, “−”, and “−”. However, the code | symbol may be prescribed | regulated as follows. The codes are arranged in the order of “+”, “−”, “+”, “+” in order from the top of the first sequence, and the codes are “+”, “+”, “+” in order from the top of the second sequence. Arranged in the order of “−” and “+”, the codes are arranged in the order of “+”, “+”, “+”, “−” in order from the top of the third series, and from the top of the fourth series. In order, the symbols are arranged in the order of “−”, “+”, “+”, “+”. Even such a code corresponds to a combination of codes of predetermined components having an orthogonal relationship between sequences.

  FIG. 11B corresponds to the first to third series in FIG. FIG. 11C is similar to the first stream and the second stream in the packet format shown in FIG. Here, the arrangement of “HT-LTF” in FIG. 11B is different from the arrangement of “HT-LTF” in FIG. That is, the HT-LTF includes only the first component and the second component. In the first sequence, HT-LTFs are arranged in the order of “HT-LTF” and “HT-LTF” from the top, and in the second sequence, HT-LTFs are arranged from the top to “HT-LTF”, “− They are arranged in the order of “HT-LTF”. If the calculation of the first component + the second component is performed on the reception signals of all sequences, the reception device extracts the desired signal for the first sequence. Also, if the first component-second component calculation is performed on all series of received signals, the receiving apparatus extracts a desired signal for the second series. These can also be said to be orthogonal as described above.

  Hereinafter, modifications according to the present invention will be described. The modification of this invention is related with the base station apparatus 34 provided with the several local oscillation part 166 corresponding to each of the some base station antenna 14 and the said some base station antenna 14 similarly to an Example. However, unlike the embodiment, the base station apparatus 34 according to the modification does not perform adaptive array antenna processing, but performs diversity processing such as equal gain combining and maximum ratio combining on signals received by the plurality of base station antennas 14. . Since the configuration of the base station apparatus 34 according to the modification is the same type as that in FIG. 1, the description thereof is omitted here.

  FIG. 12 shows the configuration of the signal processing unit 18 according to a modification of the present invention. The signal processing unit 18 in FIG. 12 corresponds to the reception function of the signal processing unit 18 in FIG. 5, and includes a synthesis unit 180 and a phase calculation unit 182, and the synthesis unit 180 is a first generically referred to as a multiplication unit 62. A multiplier 62a, a second multiplier 62b, an Nth multiplier 62n, and an adder 64 are included. Further, the first phase rotation signal 370a, the second phase rotation signal 370b, the Nth phase rotation signal 370n, which are collectively referred to as the phase rotation signal 370 as signals, and the first multiplication signal 372a, which is collectively referred to as the multiplication signal 372, and the second multiplication signal. 372b and an Nth multiplication signal 372n. Of the signal processing unit 18 in FIG. 12, components having the same reference numerals as the members included in the signal processing unit 18 in FIG. 5 perform the same operation, and thus the description thereof is omitted.

  The phase calculation unit 182 calculates the phase rotation signal 370 necessary for the phase rotation of the digital reception signal 300 from the digital reception signal 300 and the reference signal 306 for each base station antenna 14 unit and subcarrier unit over the period of the training signal. To do. Here, the phase rotation signal 370 has a value for aligning the phases of the plurality of digital reception signals 300. Further, the value of the phase rotation signal 370 may be indicated by a vector value or may be indicated by a phase value.

  The classification unit 50 uses the phase rotation signal 370 derived by the phase calculation unit 182 to rotate one of the plurality of phase rotation results when the digital reception signal 300 is rotated in units of base station antennas 14 and subcarriers. Classification is performed so that the reference signal is obtained, and the remainder of the plurality of phase rotation results is the signal to be processed. That is, the classification unit 50 performs the same process as the classification unit 50 in FIG. The multiplier 62 rotates the phase of the digital received signal 300 in units of base station antennas 14 and subcarriers in accordance with the phase rotation signal 370 and outputs a multiplication signal 372. Here, the multiplication signal 372 is also output in units of base station antennas 14 and subcarriers. Furthermore, the adding unit 64 combines the plurality of multiplication signals 372 in units of subcarriers. As a result, the reference signal and the signal to be processed are combined on a subcarrier basis.

  On the other hand, after the training signal period ends, the phase calculation unit 182 updates the phase rotation signal 370 for each base station antenna 14 and subcarrier based on the multiplication signal 372. The phase calculator 182 detects an error of the phase component of the other multiplication signal 372 with respect to the phase component of the first multiplication signal 372a for each base station antenna 14 unit. This corresponds to an error in the phase component of the signal to be processed with respect to the phase component of the reference signal. Specifically, the phase calculator 182 derives a phase error for each subcarrier for one base station antenna 14. The derivation of the phase error is realized by subtraction.

  Further, the phase calculator 182 detects an error of the phase component of the base station antenna 14 unit by integrating or averaging a plurality of phase errors with respect to one base station antenna 14. The phase error is integrated or averaged in the same manner as the processing in the integration unit 254 in FIG. In addition, the phase calculation unit 182 uses the detected phase component error of the base station antenna 14 unit as a processing target signal based on, for example, a phase amount that reversely rotates by a phase corresponding to the phase component error. The corresponding phase rotation signal 370 is updated in units of base station antennas 14 and subcarriers. The phase calculation unit 182 outputs the updated phase rotation signal 370 to the multiplication unit 62.

  FIG. 13 shows a configuration of a signal processing unit 18 according to still another modification of the present invention. The signal processing unit 18 includes a first FFT unit 40a, a second FFT unit 40b, an NFFT unit 40n, a classification unit 50, a phase rotation unit 190, a synthesis unit 180, a measurement unit 200, and an initial phase error detection unit, which are collectively referred to as the FFT unit 40. 210, a phase error detection unit 212, an initial synchronization signal detection unit 214, and a reference signal storage unit 70. The phase rotation unit 190 includes a first multiplication unit 216a, a second multiplication unit 216b, and an Nth multiplication unit 216n, which are collectively referred to as a multiplication unit 216. The signals include a first digital reception signal 300 a, a second digital reception signal 300 b, an N-th digital reception signal 300 n, a combined signal 304, a reference signal 306, and a signal processing unit control signal 310, which are collectively referred to as the digital reception signal 300.

  The measurement unit 200 measures the reception power of the digital reception signal 300 during the training signal period, and selects the digital reception signal 300 having the highest reception power as a reference signal. As described above, the digital reception signal 300 other than the reference signal is set as the processing target signal. The above processing is performed in the same manner as the measurement unit 200 of FIG. Information regarding the selected reference signal is output as a reference notification signal 352. Here, the recognition during the training signal period is performed by the signal processing unit control signal 310.

  The classification unit 50 changes the order of the digital reception signals 300 in accordance with the reference notification signal 352 after the training signal period ends. Specifically, the reference signal is input to the first multiplier 62a in the multiplier 62 described later. On the other hand, during the training signal period, the input digital reception signal 300 may not be replaced, or the order of the digital reception signal 300 may be replaced based on the reference notification signal 352 in the previous burst signal. That is, the classification unit 50 performs selection so that one of the plurality of digital reception signals 300 becomes a reference signal, and performs selection so that the remaining becomes a signal to be processed. Note that the digital reception signal 300 after the classification by the classification unit 50 is also referred to as a digital reception signal 300.

  The initial phase error detection unit 210 calculates the phase error of the signal to be processed with respect to the reference signal in the digital reception signal 300 within the period of the training signal for each base station antenna 14 until the training signal period ends. To determine the initial phase error. The calculation of the initial phase error of the base station antenna 14 unit is performed in the same manner as the calculation of the phase error in the phase calculation unit 182 of FIG. 12, and thus the description thereof is omitted here. The initial phase error detection unit 210 does not operate after the end of the training signal period, holds the initial phase error, and outputs the initial phase error to the phase error detection unit 212.

  After the training signal period ends, the phase error detection unit 212 sequentially calculates the phase error of the signal to be processed with respect to the reference signal in the digital reception signal 300 for each base station antenna 14, and the initial phase error is calculated from the calculated phase error. Each component is removed. That is, the initial phase error detection unit 210 and the phase error detection unit 212 have an error of the phase component of the processing target signal with respect to the phase component of the reference signal, and an error detected for each base station antenna 14 unit is the training signal. After this period, a correction value is generated for each base station antenna 14 so that the value in the period of the training signal is maintained.

  Multiplier 216 multiplies digital reception signal 300 and the correction value generated in phase error detector 212 by base station antenna 14 units and subcarrier units. That is, the multiplication unit 216 rotates the phase of the processing target signal in units of the base station antenna 14 and subcarriers by the correction value of the base station antenna 14 generated in the phase error detection unit 212. As a result, the phase relationship between the digital reception signals 300 after the end of the training period is close to the phase relationship during the training period. Note that the multiplication result in the multiplication unit 216 is also referred to as a digital reception signal 300.

  The initial synchronization signal detection unit 214 generates a signal for aligning the phase between the digital reception signal 300 from the digital reception signal 300 and the reference signal 306 during the training signal period. The initial synchronization signal detection unit 214 generates a phase rotation signal for aligning the phases of the digital reception signal 300 by performing inverse modulation on the digital reception signal 300 using the reference signal 306. Such a phase rotation signal can be said to be a regenerated carrier wave. The phase rotation signal is generated for each base station antenna 14 and subcarrier.

  The multiplier 62 rotates the output signal of the multiplier 216 in units of base station antennas 14 and subcarriers based on the phase rotation signal generated in the initial synchronization signal detector 214, and the adder 64 outputs the phase rotation result. The synthesized signal 304 is generated by synthesizing. That is, the multiplying unit 62 rotates the phase of the reference signal and the signal to be processed that has been phase-rotated in the phase rotating unit 190 by the phase rotation signal in units of the base station antenna 14 and the subcarrier, and the adding unit 64 outputs the result. Combining in subcarrier units. The reference signal storage unit 70 outputs a known training signal stored in advance during the training signal period as a reference signal 306.

  According to the embodiment of the present invention, the received weight vector after the end of the period of the training signal is updated so as to maintain an error between a plurality of multiplication results in the period of the training signal, so that there is a frequency offset. However, the phase relationship in the period of the training signal can be maintained between the multiplication results before synthesis. Even when the local oscillator provided for multiple base station antennas has a frequency offset, the phase error between multiple multicarrier signals obtained when receiving the training signal is reduced. Since the reception weight vector is updated so as to be maintained, the influence of the frequency offset can be reduced.

  Further, since the reception weight vector is updated so as to maintain the phase error in the period in which the training signal is received even during the period in which the training signal is not received, the influence of the frequency offset can be reduced. In addition, since the reference signal is a multicarrier signal having the largest reception power among a plurality of multicarrier signals, the accuracy of the reference signal can be improved. In addition, since only the phase error with the reference signal is maintained, the amount of processing can be reduced. In addition, since the correction value for updating the reception weight vector is generated by integrating the phase error for each subcarrier, the influence of noise can be reduced. In addition, since the influence of noise is reduced, reception characteristics can be improved.

  Further, even after the end of the training signal period, the frequency component can be corrected because the phase component of the signal to be processed is aligned with the phase component of the reference signal. Further, since the phase error is derived by combining or averaging a plurality of components for each base station antenna unit, the influence of noise can be reduced. Further, even after the end of the period of the training signal, the phase component of the processing target signal is rotated so as to maintain the phase error from the reference signal in the period of the training signal, and thus occurs after the end of the period of the training signal. The shift of the phase component can be corrected. Since the shift of the phase component can be corrected, the influence of the frequency offset can be reduced.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the embodiment of the present invention, the received weight vector calculation unit 68 uses an adaptive algorithm for estimating the received weight vector signal 312. However, the present invention is not limited to this. For example, processing other than the adaptive algorithm may be executed in the reception weight vector calculation unit 68, and the reception weight vector calculation unit 68 may obtain the reception weight vector signal 312 by correlation processing with a known signal. Good. In addition, the reception weight vector calculation unit 68 may perform direction-of-arrival estimation such as a MUSIC (Multiple Signal Classification) algorithm that is different from the adaptive algorithm and the correlation processing. According to this modification, the desired wave and the unnecessary wave can be identified in more detail. That is, a plurality of received signals may be separated in the signal processing for the adaptive array antenna.

  In the embodiment of the present invention, the communication system 100 is applied to the communication system 100 based on CSMA. However, the present invention is not limited to this, and for example, the base station apparatus 34 may be applied to a communication system other than CSMA, for example, TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access), SDMA (Space Division Multiple Access), and the like. May be used. According to this modification, the present invention can be applied to various communication systems. That is, the base station device 34 that receives a signal from the terminal device 10 may be used.

  In the embodiment of the present invention, the signal processing unit 18 performs equal gain combining diversity. However, the present invention is not limited to this, and for example, diversity of maximum ratio synthesis may be used. In this case, a weighting unit that performs weighting according to the power ratio between the digital reception signals 300 is added before the addition unit 64. According to this modification, the error rate of the received signal can be improved. That is, it may be applied to the case where the phases between a plurality of signals are aligned.

  In the embodiment of the present invention, the object of description is the base station device 34. However, the present invention is not limited to this. For example, the terminal device 10 may be the subject of the description. At that time, the terminal device 10 is configured in the same manner as the base station device 34. Moreover, not only the terminal device 10 and the base station device 34, but generally a wireless device may be used. According to this modification, the present invention can be applied to various wireless devices.

  In the embodiment of the present invention, in order to derive the phase error of the base station antenna 14 unit, the inter-signal error detection unit 124 accumulates phase errors corresponding to a plurality of subcarriers over one OFDM symbol. However, the present invention is not limited to this. For example, the inter-signal error detection unit 124 may perform integration while performing weighting. For the weighting, the base station antenna 14 corresponding to the phase error and the magnitude of the received weight vector component at the subcarrier are used. When the magnitude of the component of the reception weight vector is increased, this corresponds to a reduction in the magnitude of the digital reception signal 300 to be multiplied with the component, which also corresponds to a low reliability of the phase error. Therefore, when the magnitude of the component of the reception weight vector is large, the phase error is integrated while reducing the weight. The weighted phase error Eij ′ for the I-th base station antenna 14i and the subcarrier number j is expressed as follows.

ここで、ｗｉｊは、受信ウエイトベクトルのうち、第Ｉ基地局用アンテナ１４ｉおよびサブキャリア番号ｊに対応した成分である。さらに、重みづけのなされた位相誤差Ｅｉｊ’をもとに、Δθｉは、次のように導出される。

なお、信号間誤差検出部１２４は、重みづけの演算を行わない場合であっても、受信ウエイトベクトルの成分の大きさを監視し、受信ウエイトベクトルの成分の大きさがしきい値よりも大きくなった場合、当該受信ウエイトベクトルの成分に対応した位相誤差を積算から除外してもよい。本変形例によれば、信頼性の低い位相誤差の影響が小さくなるので、基地局用アンテナ１４単位の位相誤差の精度を向上できる。つまり、位相誤差を導出する際に雑音の影響が低減されればよい。

Here, wij is a component of the reception weight vector corresponding to the I-th base station antenna 14i and the subcarrier number j. Further, Δθi is derived as follows based on the weighted phase error Eij ′.

The inter-signal error detection unit 124 monitors the magnitude of the received weight vector component even when the weighting calculation is not performed, and the magnitude of the received weight vector component is larger than the threshold value. In this case, the phase error corresponding to the received weight vector component may be excluded from the integration. According to this modification, the influence of the phase error with low reliability is reduced, so that the accuracy of the phase error of the base station antenna 14 unit can be improved. That is, it is only necessary to reduce the influence of noise when deriving the phase error.

  In the embodiment of the present invention, the signal processing unit 18 performs processing such that the error of the phase component of the signal to be processed with respect to the phase component of the reference signal maintains a value of “0” even after the training signal period. However, the present invention is not limited to this. For example, when the error of the phase component is not “0” at the end of the training signal period, the signal processing unit 18 performs processing to maintain the value of the error of the phase component. May be. At this time, the initial weight vector calculation unit 120 obtains the error of the phase component of the signal to be processed with respect to the phase component of the reference signal as the initial phase error for each base station antenna 14 at the end of the training signal period. The initial phase error is a phase error derived from the multiplication result of the received weight vector derived from the training signal period and the training signal, and can be said to be an initial value of the phase error between the reference signal and the signal to be processed. Since the acquisition of the initial phase error may be performed in the same manner as the acquisition of the phase error in the reception weight vector update unit 114, description thereof is omitted here. Such an initial phase error is input to the reception weight vector update unit 114. The reception weight vector update unit 114 acquires the phase error as described above, but derives the correction value based on the difference between the phase error and the initial phase error. According to this modification, the present invention can be applied even when the phase component error is not “0” at the end of the training signal period. That is, the signal processing unit 18 may perform a process such that the error of the phase component of the processing target signal with respect to the phase component of the reference signal maintains the value in the training signal period even after the training signal period.

It is a figure which shows the spectrum of the multicarrier signal which concerns on the Example of this invention. It is a figure which shows the structure of the communication system which concerns on the Example of this invention. It is a figure which shows the structure of the signal of the frequency domain in FIG. It is a figure which shows the structure of the 1st radio | wireless part of FIG. It is a figure which shows the structure of the signal processing part of FIG. It is a figure which shows the structure of the reception weight vector calculation part of FIG. It is a figure which shows the structure of the initial weight vector calculation part of FIG. It is a figure which shows the structure of the reception weight vector update part of FIG. It is a figure which shows the structure of the error detection part between signals of FIG. 3 is a flowchart showing a weight vector update processing procedure of FIG. 2. 11A to 11C are diagrams showing the format of the packet signal processed in FIG. It is a figure which shows the structure of the signal processing part which concerns on the modification of this invention. It is a figure which shows the structure of the signal processing part which concerns on another modification of this invention.

Explanation of symbols

  10 terminal device, 12 radio unit, 14 base station antenna, 16 terminal antenna, 18 signal processing unit, 20 modem unit, 22 baseband unit, 24 control unit, 26 baseband unit, 28 modem unit, 30 radio unit, 32 network, 34 base station apparatus, 100 communication system.

Claims (8)

A receiving unit for receiving a plurality of multicarrier signals each including a known signal continuously in a predetermined period via a plurality of antennas;
A deriving unit for deriving a phase rotation signal for aligning the phase in units of antennas and carriers for a plurality of multi-carrier signals received by the receiving unit over a period including at least a known signal;
When a plurality of multicarrier signals received by the receiving unit are phase-rotated in antenna units and carrier units by the phase rotation signal derived in the deriving unit, one of the plurality of phase rotation results becomes a reference signal, A combining unit including means for performing classification so that the remainder of the plurality of phase rotation results is a signal to be processed, and means for combining the reference signal and the signal to be processed in units of antennas and carriers;
An error detection unit that detects an error of the phase component of the signal to be processed with respect to the phase component of the reference signal that has been phase-rotated in the combining unit, for each antenna after a period in which the known signal is included;
Based on the error of the phase component of the antenna unit detected by the error detection unit, the phase rotation signal to be processed corresponding to the signal to be processed is updated to the antenna unit and the carrier unit, and the updated phase rotation signal is output to the synthesis unit An update unit to
A receiving apparatus comprising: A receiving unit for receiving a plurality of multicarrier signals each including a known signal continuously in a predetermined period via a plurality of antennas;
A classification unit that selects one of a plurality of signals as a reference signal among a plurality of multicarrier signals received by the reception unit, and sets the rest of the plurality of signals as a processing target signal;
An error in the phase component of the signal to be processed with respect to the phase component of the reference signal selected in the classification unit, and the error detected for each antenna includes a known signal even after a period in which the known signal is included. A first generation unit that generates a correction value for each antenna so as to maintain a value in a predetermined period;
A phase rotation unit that rotates a signal to be processed in a unit of antenna and a unit of carrier by a correction value of the unit of antenna generated in the first generation unit;
A second generator that generates a phase rotation signal for aligning the phases of a plurality of multicarrier signals received by the receiver in units of antennas and carriers over a period including at least a known signal;
A combining unit that rotates the phase of the reference signal and the processing target signal phase-rotated in the phase rotation unit by the phase rotation signal generated in the second generation unit in units of antennas and carriers, and combines the results in units of carriers;
A receiving apparatus comprising: A receiving unit for receiving a plurality of multicarrier signals each including a known signal continuously in a predetermined period via a plurality of antennas;
A deriving unit for deriving weighting factors in units of antennas and carriers over a period in which at least known signals are included for a plurality of multicarrier signals received in the receiving unit;
When performing multiplication while associating antennas and carriers with the weighting factor derived by the deriving unit and the plurality of multicarrier signals received by the receiving unit, one of the multiple multiplication results is A combining unit including a unit that performs classification so that the remainder of a plurality of multiplication results becomes a processing target signal, and a unit that combines the plurality of multiplication results in units of carriers;
The error of the phase component of the signal to be processed with respect to the phase component of the reference signal multiplied by the combining unit is maintained at a value in the period including the known signal even after the period including the known signal. A generation unit that generates a correction value for each antenna;
An update unit that updates the weighting factor to be processed corresponding to the signal to be processed to the antenna unit and the carrier unit, and outputs the updated weighting factor to the combining unit, according to the correction value of the antenna unit generated in the generating unit;
A receiving apparatus comprising: A receiving unit for receiving a plurality of multicarrier signals each including a known signal continuously in a predetermined period via a plurality of antennas;
A deriving unit for deriving weighting factors in units of antennas and carriers over a period in which at least known signals are included for a plurality of multicarrier signals received in the receiving unit;
When performing multiplication while associating antennas and carriers with the weighting factor derived by the deriving unit and the plurality of multicarrier signals received by the receiving unit, one of the multiple multiplication results is A combining unit including a unit that performs classification so that the remainder of a plurality of multiplication results becomes a processing target signal, and a unit that combines the plurality of multiplication results in units of carriers;
The error of the phase component of the signal to be processed with respect to the phase component of the reference signal multiplied by the combining unit is maintained at a value in the period including the known signal even after the period including the known signal. A generation unit that generates a correction value for each antenna;
An update unit that updates the weighting factor to be processed corresponding to the signal to be processed to the antenna unit and the carrier unit, and outputs the updated weighting factor to the combining unit, according to the correction value of the antenna unit generated in the generating unit;
A demodulator that demodulates the multicarrier signal synthesized in the synthesizer;
A receiving apparatus comprising:   The receiving apparatus according to claim 3 or 4, wherein the receiving unit receives a plurality of multicarrier signals by local signals output from local oscillators respectively corresponding to the plurality of antennas. A measuring unit for measuring the strength of each of a plurality of multicarrier signals received by the receiving unit;
The receiving apparatus according to claim 3, wherein the combining unit determines a reference signal according to the intensity measured by the measuring unit. Multiple antennas,
A receiving unit for receiving a plurality of multicarrier signals each including a known signal continuously included in a predetermined period via the plurality of antennas;
A deriving unit for deriving weighting factors in units of antennas and carriers over a period in which at least known signals are included for a plurality of multicarrier signals received in the receiving unit;
When performing multiplication while associating antennas and carriers with the weighting factor derived by the deriving unit and the plurality of multicarrier signals received by the receiving unit, one of the multiple multiplication results is A combining unit including a unit that performs classification so that the remainder of a plurality of multiplication results becomes a processing target signal, and a unit that combines the plurality of multiplication results in units of carriers;
The error of the phase component of the signal to be processed with respect to the phase component of the reference signal multiplied by the combining unit is maintained at a value in the period including the known signal even after the period including the known signal. A generation unit that generates a correction value for each antenna;
An update unit that updates the weighting factor to be processed corresponding to the signal to be processed to the antenna unit and the carrier unit, and outputs the updated weighting factor to the combining unit, according to the correction value of the antenna unit generated in the generating unit;
A demodulator that demodulates the multicarrier signal synthesized in the synthesizer;
A wireless device comprising: Receiving a plurality of multicarrier signals each including a known signal continuously in a predetermined period via a plurality of antennas;
Deriving a weighting factor for each antenna and carrier for a plurality of received multicarrier signals over a period including at least a known signal;
When performing multiplication while associating antennas and carriers with the derived weighting factor and a plurality of received multicarrier signals, one of the multiplication results becomes a reference signal, and a plurality of multiplications are performed. Performing classification so that the remainder of the result is the signal to be processed;
A correction value is generated for each antenna so that the error of the phase component of the signal to be processed with respect to the phase component of the reference signal maintains the value in the period including the known signal even after the period including the known signal. And steps to
Updating the weighting factor that should correspond to the signal to be processed to the antenna unit and the carrier unit by the generated correction value of the antenna unit;
A receiving method comprising:

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