JP6209105B2 - Transmitter, XPD correction calculation coefficient calculation device, XPD correction calculation coefficient calculation method, and computer program - Google Patents

Description

  The present invention relates to a transmitter, an XPD correction calculation coefficient calculation device, an XPD correction calculation coefficient calculation method, and a computer program.

  Wireless communication systems such as LTE (Long Term Evolution) standards and WiMAX (Worldwide Interoperability for Microwave Access) standards use MIMO (Multiple Input Multiple Output) technology to increase throughput. The MIMO technique is a technique for increasing throughput by performing spatial multiplexing using a plurality of antennas on each of a transmitter side and a receiver side. In this spatial multiplexing, the multiplexed signals are separated and demodulated using the fact that there are differences in the propagation paths between a plurality of transmission / reception antennas. Therefore, in a place where direct waves are dominant, such as a line-of-sight environment, the correlation between the propagation paths becomes high, and the effect of spatial multiplexing is reduced.

  In view of this, a technique has been proposed in which the correlation of the propagation path is kept low by using transmission antennas having different polarizations. As the orthogonal polarization, for example, orthogonal polarization of vertical polarization (V polarization) and horizontal polarization (H polarization), a combination of right-handed circular polarization and left-handed circular polarization, etc. can be used. . Here, for example, it is desirable that the signal transmitted from the transmission antenna for V polarization is only the V polarization component, but actually includes the H component. Similarly, a signal transmitted from a transmission antenna for H polarization includes a V polarization component. Cross polarization discrimination (XPD) is known as an index representing the power difference between the polarizations. Considering the signal flow from the transmitter to the receiver, in addition to the above-mentioned XPD due to the non-ideal transmit antenna, XPD generated by rotating the polarization plane in the middle of the propagation path, the receive antenna There is XPD.

  In the prior art described in Patent Document 1, the orthogonal polarization power ratio calculated by the receiver is transmitted to the transmitter side, and the XPD of the transmitter is adjusted based on the orthogonal polarization power ratio.

JP 2012-49740 A

  However, the above-described prior art in Patent Document 1 does not consider that the frequency characteristics are not uniform among the subcarriers. For this reason, there exists a subject that XPD in each subcarrier cannot fully be corrected. XPD also depends on the directivity direction of the transmission antenna. For this reason, when performing beam forming used in the “Massive-MIMO” technology studied by 3GPP (3rd Generation Partnership Project), the value of XPD varies depending on the direction of the transmission beam. Will also be different.

  The present invention has been made in view of such circumstances, and in an orthogonal polarization communication system using a plurality of subcarriers, a transmitter capable of improving the cross polarization discrimination of each subcarrier, An object is to provide an XPD correction calculation coefficient calculation device, an XPD correction calculation coefficient calculation method, and a computer program.

(1) A transmitter according to the present invention is a coefficient storage for storing XPD correction calculation coefficients used for XPD correction calculation for each subcarrier in a transmitter of an orthogonal polarization communication system using a plurality of subcarriers. And an XPD correction calculation unit that performs an XPD correction calculation on the transmission signal of each subcarrier using the XPD correction calculation coefficient of the subcarrier.

(2) In the transmitter according to the present invention, in the transmitter of (1), the coefficient storage unit stores the XPD correction calculation coefficient by beam direction for each subcarrier, and the XPD correction calculation unit includes: The XPD correction calculation is performed for each subcarrier using the XPD correction calculation coefficient corresponding to the beam direction.

(3) In the transmitter according to (2), the coefficient storage unit stores the XPD correction calculation coefficient separately for each polarization beam direction for each subcarrier, and the XPD correction The calculation unit performs the XPD correction calculation using the XPD correction calculation coefficient corresponding to the beam direction of each polarization for each subcarrier.

(4) An XPD correction calculation coefficient calculation apparatus according to the present invention is an XPD correction calculation coefficient calculation apparatus that calculates an XPD correction calculation coefficient used in any one of the transmitters (1) to (3), A correlation calculation is performed between a received signal at a receiver of a known signal transmitted for each polarization from a transmitter and the known signal, and the XPD correction calculation coefficient is calculated using the correlation calculation result. And

(5) The XPD correction calculation coefficient calculation apparatus according to the present invention is the XPD correction calculation coefficient calculation apparatus according to (4), wherein a reception signal at a receiver of a known signal repeatedly transmitted from the transmitter for each polarization is received. The XPD correction calculation coefficient is calculated by averaging and using a difference between the averaged received signal and the known signal.

(6) The XPD correction calculation coefficient calculation apparatus according to the present invention is the XPD correction calculation coefficient calculation apparatus according to (5), wherein the known signal repeatedly transmitted from the transmitter for each polarization is a known signal of each polarization. wherein the but has been transmitted by the orthogonal subcarriers respectively.

(7) The XPD correction calculation coefficient calculation apparatus according to the present invention is the XPD correction calculation coefficient calculation apparatus according to (5), wherein the known signal repeatedly transmitted from the transmitter for each polarization is a known signal for each polarization. and characterized in that but transmitted by time division.

(8) The XPD correction calculation coefficient calculation apparatus according to the present invention is the XPD correction calculation coefficient calculation apparatus according to any one of (4) to (7), wherein the XPD correction calculation of the subcarrier or the received signal satisfies the predetermined transmission quality. Only coefficients are used in the transmitter.

(9) The XPD correction calculation coefficient calculation apparatus according to the present invention is the XPD correction calculation coefficient calculation apparatus according to (8), wherein only the XPD correction calculation coefficient calculated from a received signal having a K factor higher than a predetermined threshold is transmitted. It is intended to be used in a machine.

(10) The XPD correction calculation coefficient calculation method according to the present invention is an XPD correction calculation coefficient calculation method for an XPD correction calculation coefficient calculation apparatus that calculates XPD correction calculation coefficients used in the transmitters (1) to (3) above. The XPD correction calculation coefficient calculation device performs a correlation calculation between the received signal at the receiver of the known signal transmitted for each polarization from the transmitter and the known signal, and uses the correlation calculation result. And calculating the XPD correction calculation coefficient.

(11) A computer program according to the present invention provides a computer of an XPD correction calculation coefficient calculation device for calculating XPD correction calculation coefficients used in the transmitters (1) to (3) described above, for each polarization from the transmitter. A computer program for realizing a function of performing a correlation operation between a reception signal of a known signal transmitted to the receiver and the known signal and calculating the XPD correction calculation coefficient using the correlation calculation result It is characterized by being.

  According to the present invention, in an orthogonal polarization communication system using a plurality of subcarriers, an effect is obtained that the cross polarization discrimination degree of each subcarrier can be improved.

It is a block diagram which shows the structure of the transmitter 1 which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the coefficient memory | storage part 111 which concerns on one Embodiment of this invention. It is a time chart for demonstrating the transmission procedure of the known signal which concerns on Example 2 of this invention. It is a time chart for demonstrating the transmission procedure of the known signal which concerns on Example 3 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a transmitter 1 according to an embodiment of the present invention. The transmitter 1 is used in an orthogonal polarization communication system that uses a plurality of subcarriers. In an orthogonal polarization communication system, a transmitter and a receiver perform radio communication using orthogonal polarization. Examples of the orthogonal polarization communication system include a radio communication system using MIMO technology (hereinafter referred to as a MIMO communication system), a polarization multiplexing communication system used in FWA (Fixed Wireless Access), and the like. Examples of orthogonal polarization include a combination of vertical polarization (V polarization) and horizontal polarization (H polarization), circular polarization (combination of right-handed circular polarization and left-handed circular polarization), or diagonal polarization. An orthogonal polarization such as a wave (a combination of +45 degree polarization and −45 degree polarization) can be used.

  In the present embodiment, a MIMO communication system will be described as an example of an orthogonal polarization communication system. Further, vertical polarization (V polarization) and horizontal polarization (H polarization) will be described as examples of orthogonal polarization. In addition, the MIMO communication system according to the present embodiment uses an orthogonal frequency division multiplexing (OFDM) system, which is an example of a multicarrier transmission system that uses a plurality of subcarriers.

  In FIG. 1, a transmitter 1 includes a subcarrier mapping unit 101, a cross polarization discrimination (XPD) correction calculation unit 102, a frequency characteristic correction unit 103, an inverse fast Fourier transform (IFFT) unit 104, a cyclic prefix. (Cyclic prefix: C / P) insertion unit 105, digital-analog conversion (DAC) unit 106, radio unit 107, phase / amplitude adjustment unit 108, and a plurality (three in the example of FIG. 1) of V-bias. A wave antenna ANT_V, a plurality (three in the example of FIG. 1) of H-polarized antennas ANT_H, and a controller 110. The control unit 110 includes a coefficient storage unit 111.

  The subcarrier mapping unit 101, the frequency characteristic correction unit 103, the IFFT unit 104, the C / P insertion unit 105, the DAC unit 106, the radio unit 107, and the phase / amplitude adjustment unit 108 are the V polarization antenna ANT_V group and the H polarization antenna. It is provided separately from the ANT_H group. The XPD correction calculation unit 102 and the control unit 110 are provided in common for the V polarization antenna ANT_V group and the H polarization antenna ANT_H group.

  Subcarrier mapping section 101 maps the input transmission signal (primary modulated transmission signal) to each subcarrier of the OFDM signal. The XPD correction calculation unit 102 performs XPD correction calculation on the transmission signal after mapping to each subcarrier by the subcarrier mapping unit 101. This XPD correction calculation is expressed by [Equation 1].

Here, k is a subcarrier number. S _v (k) is a transmission signal mapped to the k-th subcarrier by the subcarrier mapping unit 101 provided corresponding to the V polarization antenna ANT_V group. S _h (k) is a transmission signal mapped to the kth subcarrier by the subcarrier mapping unit 101 provided corresponding to the H polarization antenna ANT_H group. S _v ′ (k) is a transmission signal of the k-th subcarrier input to the frequency characteristic correction unit 103 provided corresponding to the V polarization antenna ANT_V group. S _h ′ (k) is a transmission signal of the k-th subcarrier input to the frequency characteristic correction unit 103 provided corresponding to the H polarization antenna ANT_H group. a (k), b (k), c (k) and d (k) are complex coefficients (complex coefficients).

In [Equation 1], the complex multiplication of the transmission signals S _v (k), S _h (k) and the corresponding complex coefficients a (k), b (k), c (k), d (k) is performed. The complex coefficients a (k), b (k), c (k), and d (k) are input from the control unit 110 to the XPD correction calculation unit 102.

  The complex coefficients a (k), b (k), c (k), and d (k) are stored in the coefficient storage unit 111 in advance. The control unit 110 outputs the complex coefficients a (k), b (k), c (k), and d (k) stored in the coefficient storage unit 111 to the XPD correction calculation unit 102.

  FIG. 2 is a diagram illustrating a configuration example of the coefficient storage unit 111 according to the present embodiment. In FIG. 2, the coefficient storage unit 111 has complex coefficients a (k), b (k), c (k), d (k) for combinations of subcarrier numbers, V polarization beam directions, and H polarization beam directions. ) Is memorized. Accordingly, the coefficient storage unit 111 stores, for each subcarrier, complex coefficients a (k), b (k), c (k), for each V polarization beam direction and for each H polarization beam direction. d (k) is stored.

  If the V polarization and the H polarization are directed only in the same direction, the beam direction is not divided into the V polarization and the H polarization, and the complex coefficients a (k), b (k), c (k), and d (k) may be stored in the coefficient storage unit 111. When the beam direction is fixed, the complex coefficients a (k), b (k), c (k), and d (k) may be stored in the coefficient storage unit 111 for each subcarrier.

  For each subcarrier number, the control unit 110 stores the complex coefficients a (k), b (k), c (k), and d (k) corresponding to the V polarization beam direction and the H polarization beam direction as a coefficient storage unit. The data is read from 111 and output to the XPD correction calculation unit 102. Thereby, XPD correction according to the V polarization beam direction and the H polarization beam direction is performed for each subcarrier by the XPD correction calculation of the XPD correction calculation unit 102.

  Returning to FIG. The frequency characteristic correction unit 103 multiplies the transmission signal of each subcarrier after the XPD correction calculation performed by the XPD correction calculation unit 102 by a coefficient for correcting the frequency characteristic of the radio unit 107. This correction corrects the frequency characteristics in the transmission circuit that are not uniform due to imperfection of the analog circuit. When the frequency characteristics depend on the temperature and power supply voltage of the transmitter 1, a sensor for detecting the temperature and power supply voltage is held in the transmitter 1, and the correction coefficient is determined based on the detected value. May be. For example, a correction coefficient table that holds correction coefficients corresponding to detected values of temperature and power supply voltage is provided, and a correction coefficient corresponding to the detected value is obtained from the correction coefficient table. Since the frequency characteristic depends on the circuit, a correction coefficient is prepared separately for the transmission system for V polarization and the transmission system for H polarization.

  The IFFT unit 104 performs inverse fast Fourier transform on the transmission signal of each subcarrier after the frequency characteristic correction by the frequency characteristic correction unit 103. The C / P insertion unit 105 inserts a cyclic prefix into the transmission signal after the inverse fast Fourier transform. The DAC unit 106 converts the transmission signal (digital signal) after the cyclic prefix is inserted into an analog signal. The wireless unit 107 converts the transmission signal converted into the analog signal into a signal having a transmission frequency. The phase / amplitude adjustment unit 108 adjusts the phase and amplitude of the transmission signal having the transmission frequency. The phase and amplitude adjustment values are instructed from the control unit 110.

  Each V polarization antenna ANT_V transmits the transmission signal after the phase and amplitude are adjusted by the phase / amplitude adjustment unit 108 of its own system. Each H-polarized antenna ANT_H transmits the transmission signal after the phase and amplitude are adjusted by the phase / amplitude adjustment unit 108 of its own system.

  According to the present embodiment, a complex coefficient used for XPD correction calculation is provided for each subcarrier. Then, XPD correction calculation is performed using the complex coefficient for each subcarrier. Thereby, XPD correction calculation suitable for each subcarrier can be performed, so that the cross polarization discrimination degree of each subcarrier can be improved.

  Furthermore, when the beam direction changes, a complex coefficient used for XPD correction calculation is provided for each subcarrier separately for each beam direction. Then, XPD correction calculation is performed using the complex coefficient for each subcarrier for each beam direction. Thereby, XPD correction calculation suitable for each subcarrier and each beam direction can be performed, so that the effect of improving the cross polarization discrimination regarding each beam direction of each subcarrier can be obtained.

  In addition, when the beam direction is different for each polarization, a complex coefficient used for XPD correction calculation is provided for each subcarrier separately for each polarization beam direction. Then, for each subcarrier, XPD correction calculation is performed using the complex coefficient for each polarization beam direction. As a result, XPD correction calculation suitable for the beam direction of each subcarrier and each polarization can be performed, so that the cross polarization discrimination regarding the beam direction of each polarization of each subcarrier can be improved. Is obtained.

  Next, a method for obtaining complex coefficients (hereinafter referred to as XPD correction calculation coefficients) a (k), b (k), c (k), and d (k) used in the XPD correction calculation according to the present embodiment ( An XPD correction calculation coefficient acquisition method) will be described below with reference to examples.

  The transmission signal transmitted from the transmitter 1 is received by the receiver under the influence of the propagation path. The relationship between the transmission signal and the reception signal at the receiver is expressed by [Equation 2]. Here, for convenience of explanation, both the transmitter 1 and the receiver use a total of two antennas, one V-polarized antenna and one H-polarized antenna, and the transmitter 1 transmits with the two antennas. Assume that the receiver receives signals with the two antennas.

Here, s ₁ is a transmission signal transmitted from the V polarization antenna. s ₂ is a transmission signal transmitted from the H polarization antenna. r ₁ is a received signal received by the V polarization antenna. r ₂ is a received signal received by the H polarization antenna. H is the channel matrix of the propagation path. Q is a matrix representing a component corresponding to XPD.

  The matrix Q is expressed by [Equation 3].

Each component _q 11 of the matrix _{Q, q 12, q 21,} q 22 is calculated by [Expression 4].

Here, r _v (k, i) is the i-th received symbol of the k-th subcarrier received by the V polarization antenna. r _h (k, i) is the i th received symbol of the k th subcarrier received by the H polarization antenna. p _v (k, i) is the i-th pilot signal (known signal) of the k-th subcarrier transmitted by the V polarization antenna. p _h (k, i) is the i-th pilot signal (known signal) of the k-th subcarrier transmitted by the H polarization antenna. The pilot signals p _v (k, i) and p _h (k, i) are orthogonal to each other. i is the symbol number of each subcarrier. n is the number of symbols.

The transmitter 1 transmits a pilot signal p _v (k, i) from the V polarization antenna, and transmits a pilot signal p _h (k, i) from the H polarization antenna. The receiver acquires the received symbol r _v (k, i) by performing OFDM demodulation on the received signal received by the V polarization antenna. In addition, the receiver acquires a received symbol r _h (k, i) by performing OFDM demodulation on the received signal received by the H polarization antenna.

Using the received symbols r _v (k, i), r _h (k, i) obtained by the receiver and the known pilot signals p _v (k, i), p _h (k, i) By performing the correlation calculation of [Equation 4], each component q ₁₁ , q ₁₂ , q ₂₁ , q ₂₂ of the matrix Q is calculated. By using the matrix Q composed of the calculated components q ₁₁ , q ₁₂ , q ₂₁ , and q ₂₂ , the XPD correction operation coefficients a (k), b (k), c (k), d (k) is calculated.

Where Q ^H is a complex conjugate transpose of the matrix Q.

  The calculated XPD correction calculation coefficients a (k), b (k), c (k), and d (k) are stored in the coefficient storage unit 111 of the transmitter 1 and used for the XPD correction calculation. Note that the calculations of [Equation 4] and [Equation 5] may be performed by a calculation device (XPD correction calculation coefficient calculation device) of the receiver, or a calculation device (XPD correction calculation) provided separately from the receiver. (Coefficient calculation device).

  In addition, paying attention to subcarriers or received signals that satisfy a predetermined transmission quality, only the XPD correction calculation coefficients a (k), b (k), c (k), and d (k) of the subcarriers or received signals are used. You may do it. For example, among the received signals (known signal received signals) at the receiver of the known signal repeatedly transmitted from the transmitter 1, the known signal reception in which the K factor indicating the power ratio of the direct wave and the reflected wave is higher than a predetermined threshold value is received. Select a signal. Then, averaging is performed on the XPD correction calculation coefficients a (k), b (k), c (k), and d (k) calculated from the selected known signal reception signal.

  In the XPD correction calculation coefficient acquisition method of the first embodiment described above, there is no problem when pilot signals are transmitted and received in an environment that is not affected by channel fluctuations such as in an anechoic chamber. However, when the pilot signal is transmitted / received in an environment where the transmitter 1 is actually operated, for example, a signal reflected or diffracted by a surrounding building or the like reaches the receiver. , Affected by channel fluctuations caused by movement of receivers, surrounding people and cars. Therefore, in the XPD correction calculation coefficient acquisition method according to the second embodiment, the XPD correction calculation coefficient is calculated in a state where the influence of signals other than direct waves is removed.

[Transmission procedure of known signal at transmitter]
With reference to FIG. 3, the transmission procedure of the known signal in the transmitter 1 will be described. FIG. 3 is a time chart for explaining a known signal transmission procedure according to the second embodiment.

  First, in accordance with the transmission start timing of OFDM symbol (t = 0), a pseudo-random number sequence that is known between the transmitter and the receiver is assigned as a transmission signal. Let OFDM symbol time (not including guard interval) be T, and guard interval time be Tg. If the length of the pseudo random number sequence is N and the symbol time of the pseudo random number sequence is Tn, the pseudo random number sequence satisfies “N × Tn ≦ T”. For example, an M series can be used as the pseudo random number series. Alternatively, the pseudo-random number sequence may be any sequence as long as the correlation value with itself delayed by k × Tn is low (where k <N). Thereby, a pseudo-random number sequence (for example, M sequence) is transmitted from time “t = 0” to “t = T” (see FIG. 3).

  Next, 0 is assigned as a transmission signal from time “t = T” to “t = T + Tg” (that is, transmission is not performed). Next, from time “t = T + Tg”, transmission of an OFDM symbol (hereinafter referred to as symbol A) in which a known signal known between the transceivers is allocated to each subcarrier is started. As a result, the cyclic prefix is not added at the timing of the guard interval from time “t = T” to “t = T + Tg” (see FIG. 3). Thereafter, the symbol A is transmitted from time “t = T + Tg” to “2T + Tg” (see FIG. 3).

  The above-described transmission procedure is repeated a predetermined number of times at a cycle of “2T + 2Tg” or until an end notification is received from the receiver (see FIG. 3).

  The symbol A is generated separately for the V polarization symbol Av and the H polarization symbol Ah, and the symbol Av and the symbol Ah are transmitted at the same timing. At this time, 0 is assigned so that the subcarriers are orthogonal to each other between the symbol Av and the symbol Ah. For example, only odd-numbered subcarriers are used for the symbol Av, and only even-numbered subcarriers are used for the symbol Ah.

[Procedure for obtaining XPD correction calculation coefficient from reception signal of receiver]
The receiver receives a signal transmitted from the transmitter, and calculates a sliding correlation between the received signal and a known pseudorandom number sequence (for example, M sequence) between the transceiver. The timing at which this correlation value peak occurs is held as symbol synchronization timing. The time on the receiver side is set to t ′, and the symbol synchronization timing is set to “t ′ = 0”.

First, a received signal (time domain received signal (time signal)) from time “t ′ = T + Tg” to “t ′ = 2T + Tg” “r ₁ (i), i = 0, 1, 2, 3,.・ ”Is acquired. This time signal acquisition is repeated at a cycle of “2T + 2Tg”, and the average of the acquired time signals is calculated. Assuming that the time signal acquired at the j-th time is r _j (i), the average r (i) of the time signals is expressed by the following equation.
r (i) = (r ₁ (i) + r ₂ (i) +... + r _j (i)) / j
The average r (i) of the time signal can be handled as a result of canceling the influence of channel fluctuation in the propagation path from the transmitter 1 to the receiver.

Next, a fast Fourier transform (FFT) is performed on the average r (i) of the time signals to obtain a reception signal r (k) of each subcarrier. And
The V polarization component r _v (k) and the H polarization component r _h (k) are separated and acquired from the received signal r (k) according to an assignment known between the transceivers.

Here, signals (symbols Av, Ah) S _v (k), S _h (k) assigned to each subcarrier are known. Thereby, the difference between the V polarization component r _v (k) and the H polarization component r _h (k) acquired from the received signal and the known signals S _v (k), S _h (k) is calculated by complex division. The matrix Q of each subcarrier is obtained using the difference.

  Next, XPD correction calculation coefficients a (k), b (k), c (k), and d (k) are calculated by [Formula 5] using the matrix Q of each subcarrier.

  The third embodiment is a modification of the second embodiment described above. In the second embodiment, the V-polarized signal and the H-polarized signal are transmitted at the same timing. However, in the third embodiment, the V-polarized signal and the H-polarized signal are transmitted at different times.

  FIG. 4 is a time chart for explaining a known signal transmission procedure according to the third embodiment. As shown in FIG. 4, a signal of one polarization (V polarization in the example of FIG. 4) is transmitted from time “t = T + Tg” to “t = 2T + Tg”. Then, from time “t = 2T + 2Tg” to “t = 3T + 2Tg”, a signal of the other polarization (H polarization in the example of FIG. 4) is transmitted. The repetition period is “3T + 3Tg”.

  In the second and third embodiments, the calculation for calculating the XPD correction calculation coefficient may be performed by the calculation device (XPD correction calculation coefficient calculation device) of the receiver, or a calculation device provided separately from the receiver. (XPD correction calculation coefficient calculation device) may be used.

  In the second and third embodiments, attention is paid to subcarriers or received signals that satisfy a predetermined transmission quality, and XPD correction calculation coefficients a (k), b (k), c (k) of the subcarriers or received signals. , D (k) may be used. For example, among the received signals (known signal received signals) at the receiver of the known signal repeatedly transmitted from the transmitter 1, the known signal reception in which the K factor indicating the power ratio of the direct wave and the reflected wave is higher than a predetermined threshold value is received. Select a signal. Then, averaging is performed on the XPD correction calculation coefficients a (k), b (k), c (k), and d (k) calculated from the selected known signal reception signal.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  For example, in the above-described embodiment, the orthogonal polarization communication system is applied to the MIMO communication system, but the present invention is similarly applied to other orthogonal polarization communication systems (for example, a polarization multiplexing communication system used in FWA). Is possible.

  In the above-described embodiment, V polarization and H polarization are used as orthogonal polarization, but circular polarization (combination of right-handed circular polarization and left-handed circular polarization), oblique polarization (+45 degree polarization). A combination of a wave and -45 degree polarization) may be used.

  Further, a computer program for realizing the functions of the above-described XPD correction calculation coefficient calculation device is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. May be. Here, the “computer system” may include an OS and hardware such as peripheral devices.

  “Computer-readable recording medium” refers to a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disk), and a built-in computer system. A storage device such as a hard disk.

Further, the “computer-readable recording medium” means a volatile memory (for example, DRAM (Dynamic DRAM) in a computer system that becomes a server or a client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line. Random Access Memory)), etc., which hold programs for a certain period of time.
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

DESCRIPTION OF SYMBOLS 1 ... Transmitter, 101 ... Subcarrier mapping part, 102 ... XPD correction calculating part, 103 ... Frequency characteristic correction part, 104 ... IFFT part, 105 ... C / P insertion part, 106 ... DAC part, 107 ... Radio | wireless part, 108 ... Phase / amplitude adjustment unit, 110 ... Control unit, 111 ... Coefficient storage unit, ANT_V ... V-polarization antenna, ANT_H ... H-polarization antenna

Claims (11)

In a transmitter of an orthogonal polarization communication system using a plurality of subcarriers,
A coefficient storage unit for storing an XPD correction calculation coefficient used for XPD correction calculation for each subcarrier;
An XPD correction calculation unit that performs an XPD correction calculation on the transmission signal of each subcarrier using the XPD correction calculation coefficient of the subcarrier;
A transmitter characterized by comprising: The coefficient storage unit stores the XPD correction calculation coefficient separately for each beam direction for each subcarrier,
The XPD correction calculation unit performs the XPD correction calculation using the XPD correction calculation coefficient corresponding to the beam direction for each subcarrier.
The transmitter according to claim 1. The coefficient storage unit stores the XPD correction calculation coefficient separately for each polarization beam direction for each subcarrier,
The XPD correction calculation unit performs the XPD correction calculation using the XPD correction calculation coefficient corresponding to the beam direction of each polarization for each subcarrier.
The transmitter according to claim 2. An XPD correction calculation coefficient calculation device for calculating an XPD correction calculation coefficient used in the transmitter according to any one of claims 1 to 3,
Perform a correlation operation between the received signal at the receiver of the known signal transmitted for each polarization from the transmitter and the known signal, and calculate the XPD correction calculation coefficient using the correlation calculation result.
An XPD correction calculation coefficient calculation apparatus characterized by the above. The received signal at the receiver of the known signal repeatedly transmitted for each polarization from the transmitter is averaged, and the XPD correction calculation coefficient is calculated using the difference between the averaged received signal and the known signal. ,
The XPD correction calculation coefficient calculation apparatus according to claim 4. Known signal transmitted repeatedly from the transmitter for each polarization, XPD correction operation coefficients of claim 5 in which the known signals of each polarization is characterized in that transmitted with the subcarrier, each orthogonal Calculation device. It said known signal transmitted repeatedly from the transmitter for each polarization, XPD correction operation coefficient calculating apparatus according to claim 5, wherein the known signal for each polarization has been transmitted by time division.   8. The XPD correction calculation coefficient calculation according to claim 4, wherein only the XPD correction calculation coefficient of a subcarrier or reception signal that satisfies a predetermined transmission quality is used in the transmitter. 9. apparatus.   9. The XPD correction calculation coefficient calculation apparatus according to claim 8, wherein only the XPD correction calculation coefficient calculated from a received signal having a K factor higher than a predetermined threshold is used in the transmitter. An XPD correction calculation coefficient calculation method for an XPD correction calculation coefficient calculation apparatus that calculates an XPD correction calculation coefficient used in the transmitter according to any one of claims 1 to 3,
The XPD correction calculation coefficient calculation device performs a correlation calculation between the received signal at the receiver of the known signal transmitted for each polarization from the transmitter, and the XPD using the correlation calculation result. Calculate the correction calculation coefficient,
An XPD correction calculation coefficient calculation method characterized by the above. A computer of an XPD correction calculation coefficient calculation device that calculates an XPD correction calculation coefficient used in the transmitter according to any one of claims 1 to 3,
A function of performing a correlation operation between a received signal at a receiver of a known signal transmitted for each polarization from the transmitter and the known signal, and calculating the XPD correction calculation coefficient using the correlation calculation result;
Computer program for realizing.

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