JP2019169811A - Radio communication device and radio communication method - Google Patents

Abstract

A radio communication device as an embodiment of the present invention comprises a transmission unit that selects either a first subcarrier pattern defining a distribution of effective subcarriers and null subcarriers in a predetermined frequency band or a second subcarrier pattern defining a distribution of effective subcarriers and null subcarriers, the second subcarrier pattern having more null subcarriers than those of the first subcarrier pattern and, on the basis of the selected subcarrier pattern, transmits an OFDM-modulated first radio signal.SOLUTION: To provide a radio communication device and a radio communication method for implementing high communication quality while keeping a frequency diversity effect.SELECTED DRAWING: Figure 19

Description

  Embodiments described herein relate generally to a wireless communication apparatus and a wireless communication method.

  In wireless communication, it is known that the conditions of a propagation path change with weather. For example, when there is rain, the attenuation of radio signals increases, the signal-to-noise ratio (SNR) decreases, and the error rate of transmission information increases. If the propagation path is ill-conditioned, not all errors caused by error correction codes can be corrected. In such a case, measures are taken to reduce the bandwidth used for transmission and increase the transmission power so that the signal-to-noise ratio is improved.

  However, if the bandwidth used in wireless communication is narrowed, the wireless signal is likely to be affected by multipath fading, and the frequency diversity effect cannot be obtained. If only a narrow band is used, the signal-to-noise ratio may be lowered due to attenuation of the radio signal due to multipath fading. There is a need for the development of a technology that realizes good communication quality while maintaining the frequency diversity effect even when the conditions of the propagation path become worse.

Japanese Patent No. 5787376

  Embodiments of the present invention provide a wireless communication apparatus and a wireless communication method that achieve good communication quality while maintaining the frequency diversity effect.

  The wireless communication apparatus as an embodiment of the present invention defines a distribution of effective subcarriers and null subcarriers in a predetermined frequency band, or a distribution of effective subcarriers and null subcarriers, A transmission unit is provided that selects either the second subcarrier pattern or the second subcarrier pattern that has more null subcarriers than the first subcarrier pattern, and transmits the first radio signal that is OFDM-modulated based on the selected subcarrier pattern. .

The figure which showed the structural example of the radio | wireless communications system which concerns on 1st Embodiment. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on 1st Embodiment. The figure which showed the example of the 1st subcarrier pattern. The figure which showed the 1st example of the 2nd subcarrier pattern. The figure which showed the 2nd example of the 2nd subcarrier pattern. The figure which showed the 3rd example of the 2nd subcarrier pattern. The figure which showed the 4th example of the 2nd subcarrier pattern. The figure which showed the 5th example of the 2nd subcarrier pattern. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 1st modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on 2nd Embodiment. The figure which showed the example of the subcarrier pattern. The figure which showed the 1st example of the 3rd subcarrier pattern. The figure which showed the 2nd example of the 3rd subcarrier pattern. The figure which showed the 3rd example of the 3rd subcarrier pattern. The figure which showed the 4th example of the 3rd subcarrier pattern. The figure which showed the 5th example of the 3rd subcarrier pattern. The figure which showed the 6th example of the 3rd subcarrier pattern. The figure which showed the 7th example of the 3rd subcarrier pattern. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 2nd modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 3rd modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 4th modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 5th modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 6th modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on 3rd Embodiment. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 7th modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on an 8th modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 9th modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 10th modification. The figure which showed the structural example of the radio | wireless communication apparatus which concerns on a 11th modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  FIG. 1 shows a configuration example of a wireless communication system according to the first embodiment. The wireless communication system of FIG. 1 includes wireless communication devices 1a and 1b and computers 2a and 2b. The computer 2a is electrically connected to the wireless communication device 1a, and can send and receive data to and from the wireless communication device 1a. Similarly, the computer 2b is electrically connected to the wireless communication device 1b and can send and receive data to and from the wireless communication device 1b. Although one computer is connected to each wireless communication apparatus in the wireless communication system of FIG. 1, a TCP / IP network or the like may be configured, and the wireless communication apparatus may be connected to a plurality of computers (computer systems).

  The wireless communication device 1a includes antennas 51a and 52a. The wireless communication device 1b includes antennas 51b and 52b. The type and shape of the antenna are not particularly limited. The wireless communication devices 1a and 1b can perform wireless communication via antennas provided respectively. That is, the computers 2a and 2b can transmit and receive data to and from each other using the propagation path between the wireless communication devices 1a and 1b. The wireless communication devices 1a and 1b are both wireless communication devices that use OFDM (Orthogonal Frequency Division Multiplexing) for modulation of digital signals. The type of communication standard used by the wireless communication devices 1a and 1b is not particularly limited.

  OFDM is a technique of dividing a frequency band into a plurality of subcarriers and transmitting data in parallel in the frequency direction using each subcarrier. In OFDM, since the subcarriers are orthogonal to each other, it is possible to effectively use the frequency band by arranging the subcarriers densely. In addition, since the subcarriers can be arranged in a wide frequency band or the symbol rate can be lowered, it is possible to suppress a decrease in communication quality (signal-to-noise ratio) due to multipath fading and interference.

  FIG. 2 shows a configuration example of the wireless communication apparatus according to the first embodiment. The wireless communication device 1 in FIG. 2 includes a transmission unit 10, a reception unit 20, a host interface 30, a control unit 40, an antenna 51, and an antenna 52. The transmission unit 10 includes a primary modulation unit 11, a first OFDM modulation unit 12, a second OFDM modulation unit 13, a D / A converter 14, and a transmission amplifier 15 as internal components. The receiving unit 20 includes a low noise amplifier 21, an A / D converter 22, a first OFDM demodulator 23, a second OFDM demodulator 24, and a primary demodulator 25 as internal components. The wireless communication device 1 shows a configuration example of the wireless communication devices 1a and 1b in the example of FIG.

  The transmission unit 10 performs wireless data transmission using the antenna 51. The receiving unit 20 performs wireless data reception using the antenna 52. The host interface 30 provides means for transmitting and receiving data between the wireless communication apparatus 1 and the computer 2. Examples of the host interface 30 include PCI Express, USB, UART, SPI, SDIO, and Ethernet, but other interfaces may be used.

  The control unit 40 changes the radio frequency, transmission power, and modulation method in the radio communication apparatus 1 and performs processing such as symbol timing synchronization, carrier frequency synchronization, sampling frequency synchronization, and subcarrier information synchronization. Or Further, the control unit 40 monitors the communication quality in the wireless communication device 1 and changes the subcarrier pattern in OFDM. Note that the control unit 40 may acquire weather information such as rainfall and snowfall from an external information processing apparatus such as the computer 2, and may change subcarrier information in OFDM based on the weather information. Moreover, the control part 40 may receive the instruction | indication by a user and may change the subcarrier pattern in OFDM. The control unit 40 may store subcarrier information used by the wireless communication device 1 and other wireless communication devices for data transmission in an internal storage unit. Examples of the storage unit include a DRAM, a flash memory, and a hard disk, but the type of device is not particularly limited. The control unit 40 may perform processing such as channel estimation.

  Next, components inside the transmission unit 10 will be described.

  The primary modulation unit 11 performs primary modulation on a bit sequence of transmission data and generates a modulated signal. In the primary modulation, for example, BPSK, QPSK, QAM, etc. can be used, but other modulation schemes may be used. The modulation signal generated by the primary modulation unit 11 is transferred to the first OFDM modulation unit 12 or the second OFDM modulation unit 13 based on the setting of the control unit 40.

  The first OFDM modulation unit 12 performs modulation by OFDM to generate a first OFDM signal. The first OFDM signal is a signal in which the distribution of subcarriers (effective subcarriers) used for carrying data follows the first subcarrier pattern. The first subcarrier pattern defines a distribution of effective subcarriers used for data transmission and null subcarriers not used for data transmission in a predetermined frequency band divided into subcarriers.

FIG. 3 shows an example of a first subcarrier pattern related to the first OFDM signal. The horizontal axis in FIG. 3 indicates the frequency. In the first subcarrier pattern 60 of FIG. 3, the frequency band [f ₁ , f ₂ ] between the frequency f ₁ and the frequency f ₂ is divided into N = 41 subcarriers. Only the sub-carrier including the center frequency f _c of the frequency band has a null subcarrier is not used for data transmission, and has a subcarrier remaining 40 are used for data transmission. The sub-carrier including the center frequency f _c, since there is a danger that variations in the DC offset in the signal is mixed, nothing is common that do not carry data. However, this does not preclude the switch uses subcarriers including the center frequency f _c.

  Hereinafter, subcarriers used for data transmission are referred to as effective subcarriers. That is, subcarriers that are not set as null subcarriers can be defined as effective subcarriers. Data may be carried using an effective subcarrier, and a pilot signal, a synchronization signal, a control signal, etc. may be carried, and the use is not particularly limited. Further, the data carried by the effective subcarrier may be subjected to primary modulation or may not be subjected to primary modulation. The power of the signal in the null subcarrier usually takes a value of 0 or a value close to 0.

The first subcarrier pattern 60 in FIG. 3 is only an example. Regarding the upper limit f _{2 of} the frequency band used in communication, the lower limit f _{1 of the} frequency band used in communication, the number N of subcarrier divisions, and the width (f ₂ −f ₁ ) / N in the frequency direction occupied by each subcarrier Is not particularly limited.

  The second OFDM modulation unit 13 performs modulation by OFDM and generates a second OFDM signal. In the first OFDM signal, the distribution of effective subcarriers used for data transmission follows the second subcarrier pattern. The second subcarrier pattern is a subcarrier pattern that defines the distribution of effective subcarriers and null subcarriers and has more null subcarriers than the first subcarrier pattern.

FIG. 4 shows a first example of the second subcarrier pattern. The horizontal axis in FIG. 4 indicates the frequency. In the second subcarrier pattern 70 of FIG. 4, the frequency band [f ₁ , f ₂ ] is divided into N = 41 subcarriers similarly to the first subcarrier pattern 60. Of these, a sub-carrier including the center frequency f _c of the frequency band is set to null subcarrier not used. In the second subcarrier pattern 70, the number of effective subcarriers is 20, which is half of the first subcarrier pattern 60.

  The second subcarrier pattern 70 of FIG. 4 includes a smaller number of effective subcarriers than the first subcarrier pattern, and between the highest frequency effective subcarrier and the lowest frequency effective subcarrier, It has at least two null subcarriers that are not adjacent to each other in the frequency direction.

FIG. 5 shows a second example of the second subcarrier pattern. In the second subcarrier pattern 71 of FIG. 5, the number of effective subcarriers is set to 20 like the second subcarrier pattern 70. However, the effective subcarriers of the second subcarrier pattern 71 are distributed in a wider frequency band than the effective subcarriers of the second subcarrier pattern 70. As described above, in the second subcarrier pattern, effective subcarriers can be dispersedly arranged with null subcarriers interposed as long as they are within the range of the frequency band [f ₁ , f ₂ ] of the first subcarrier pattern.

  By using the second subcarrier pattern 71 in which the effective subcarriers are distributed in a wider frequency band, the frequency diversity effect is greater than that of the second subcarrier pattern 70.

  FIG. 6 shows a third example of the second subcarrier pattern. In the second subcarrier pattern 72 of FIG. 6, the number of effective subcarriers is set to 20 like the second subcarrier patterns 70 and 71. In the second subcarrier pattern 72, effective subcarriers are arranged in the frequency direction based on a certain rule. That is, they are regularly distributed in the frequency direction in a pattern of effective subcarriers, effective subcarriers, and null subcarriers.

  FIG. 7 shows a fourth example of the second subcarrier pattern. In the second subcarrier pattern 73 of FIG. 7, the number of effective subcarriers is set to 20 like the second subcarrier patterns 70 to 72. In the second subcarrier pattern 73, effective subcarriers are alternately arranged periodically with null subcarriers.

  If the effective subcarriers are regularly arranged as in the second subcarrier pattern 72 or the effective subcarriers are periodically arranged as in the second subcarrier pattern 73, the configuration of an electronic circuit, software, or the like Can be simplified, and the manufacturing cost of the wireless communication apparatus 1 can be reduced. Further, when the second subcarrier patterns 72 and 73 are used, the effective subcarriers can be evenly distributed in the frequency direction, and the frequency diversity effect can be easily obtained.

  The second subcarrier patterns 70 to 74 described above are only examples. If fewer effective subcarriers than the first subcarrier pattern are arranged, the number of effective subcarriers, the number of null subcarriers, the arrangement of effective subcarriers, and the arrangement of null subcarriers are not particularly limited.

  All effective subcarriers in the second subcarrier patterns 70 to 74 are distributed within a predetermined frequency band (within the frequency band related to the first subcarrier pattern). However, the effective subcarriers of the second subcarrier pattern are not necessarily arranged in the frequency band related to the first subcarrier pattern. For example, in the second subcarrier pattern, the effective subcarriers may be arranged in a band wider than the frequency band related to the first subcarrier pattern, or the effective subcarriers may be arranged in a frequency band different from the frequency band related to the first subcarrier pattern. A carrier may be arranged.

  However, in general, a wireless communication device that supports a wide frequency band is required to have higher performance and a complicated configuration, which tends to increase costs. Considering that this embodiment is also applied to a wireless communication apparatus having a relatively simple configuration, all the effective subcarriers in the second subcarrier pattern are within a predetermined frequency band (frequency band related to the first subcarrier pattern). ).

  Note that the control unit 40 may set the transmission power to be larger when generating the second OFDM signal in which the distribution of effective subcarriers follows the second subcarrier pattern compared to when generating the first OFDM signal. This may improve the signal-to-noise ratio when the propagation path conditions are poor.

  FIG. 8 shows a fifth example of the second subcarrier pattern. In the second subcarrier pattern 74 of FIG. 8, 20 subcarrier patterns are arranged. However, unlike the second subcarrier patterns 70 to 74 described above, a null subcarrier that is not used for data transmission is arranged between the effective subcarrier of the highest frequency and the effective subcarrier of the lowest frequency. Absent. The use of a pattern such as the second subcarrier pattern 74 is not excluded, but in order to disperse effective subcarriers over a wider frequency band and enhance the frequency diversity effect, the highest frequency effective in the second subcarrier pattern is used. It is desirable to place a null subcarrier between the subcarrier and the lowest frequency effective subcarrier.

  The subcarrier patterns (first subcarrier pattern and second subcarrier pattern) used by the wireless communication device 1 are shared in advance with the wireless communication device of the communication destination. Information on the subcarrier pattern to be used is called subcarrier information.

  The controller 40 performs subcarrier information synchronization processing before data transmission. In the subcarrier information synchronization processing, the control unit 40 notifies the communication destination wireless communication device of the subcarrier pattern used by the wireless communication device 1 for data transmission. If the communication destination wireless communication apparatus includes means for acquiring subcarrier information and means for demodulating the OFDM signal related to the corresponding subcarrier pattern, the wireless signal transmitted from the wireless communication apparatus 1 can be correctly demodulated. it can. Note that if it is determined that a prescribed subcarrier pattern (for example, the first subcarrier pattern) is to be used when data is transmitted for the first time by a communication protocol or the like, the subordinate wireless communication apparatus must It is not necessary to notify the carrier information.

  For example, the control unit 40 can set the wireless communication device 1 to perform data transmission using the first subcarrier pattern when the conditions of the propagation path are favorable. In addition, the control unit 40 can set the wireless communication device 1 to perform data transmission using the second subcarrier pattern when the conditions of the propagation path deteriorate due to rainfall or the like.

  For example, the control unit 40 determines that the communication quality in the propagation path with the wireless communication apparatus that is the transmission destination of the wireless signal has deteriorated (the propagation path condition has deteriorated), and determines the subcarrier pattern used for data transmission. The first subcarrier pattern can be switched to the second subcarrier pattern. Examples of indexes related to communication quality include error rate, transmission rate, and signal-to-noise ratio, but other indexes such as data transmission rate and data reception amount may be used. Examples of error rates include a code error rate and a bit error rate, but other error rates may be used. Also, if the communication quality in the received data has improved, a command is issued to request that the subcarrier pattern used for data transmission be switched from the second subcarrier pattern to the first subcarrier pattern to the wireless communication apparatus that is the transmission source. You may send it.

  Hereinafter, the wireless communication device 1 will be described with reference to FIG. 2 again.

  The D / A converter 14 converts the first OFDM signal generated by the first OFDM modulation unit 12 or the second OFDM signal generated by the second OFDM modulation unit 13 from a digital signal to an analog signal. The method of the D / A converter 14 is not particularly limited.

  The transmission amplifier 15 amplifies the analog signal converted by the D / A converter 14 and transmits it from the antenna 51. The control unit 40 can adjust the amplification factor of the analog signal in the transmission amplifier 15 based on the transmission power setting.

  Next, components inside the receiving unit 20 will be described.

  The low noise amplifier 21 amplifies an analog radio signal received from the antenna 52. The A / D converter 22 converts an analog radio signal into a digital signal. The method of the A / D converter 22 is not particularly limited. The digital signal converted by the A / D converter 22 is transferred to the first OFDM demodulator 23 or the second OFDM demodulator 24. The control unit 40 determines the transfer destination of the digital signal based on information (subcarrier information) related to the subcarrier pattern used for data transmission by the wireless communication apparatus that has transmitted the digital signal. For example, when the transmission source wireless communication apparatus uses the first subcarrier pattern, the digital signal is transferred to the first OFDM demodulator 23.

  The first OFDM demodulator 23 demodulates the first OFDM signal related to the first subcarrier pattern. The second OFDM demodulator 24 demodulates the second OFDM signal related to the second subcarrier pattern. The primary demodulator 25 performs primary demodulation on the signal transferred from the first OFDM demodulator 23 or the second OFDM demodulator 24.

  It is assumed that the control unit 40 acquires information (subcarrier information) related to a subcarrier pattern used by a wireless communication apparatus that is a data transmission source before receiving data. If it is determined by a communication protocol or the like that a prescribed subcarrier pattern (for example, the first subcarrier pattern) is used when data is transmitted for the first time, the first OFDM demodulator 23 is used to perform OFDM. Demodulation may be performed.

  Each component of the wireless communication device 1 is realized by, for example, a hardware circuit such as an ASIC, PLD, FPGA, MMIC (Monolithic Microwave Integrated Circuit), a discrete circuit, software operating on a processor, or a combination thereof. . Further, the frequency, frequency band width, transmission power size, and communication protocol used by the wireless communication apparatus 1 in wireless communication are not particularly limited.

  The configuration of the wireless communication device 1 in FIG. 1 is only an example. Therefore, you may use the radio | wireless communication apparatus which concerns on a different structure from this. For example, the wireless communication apparatus may include a filter circuit such as a bandpass filter or a lowpass filter, or may include a component related to frequency conversion such as a local oscillator or a mixer circuit. In the example of FIG. 1, the transmitting antenna and the receiving antenna are separate antennas, but a common antenna may be used for transmitting and receiving.

  The transmission amplifier 15 and the antenna 51 that realize transmission of analog radio frequency radio signals, and the low-noise amplifier 21 and the antenna 52 that realize reception of analog radio frequency radio signals are wirelessly connected to the radio communication apparatus 1. It is an example of the component which concerns on a part.

  Further, the number of first subcarrier patterns and second subcarrier patterns used by the wireless communication apparatus is not particularly limited. Therefore, the wireless communication apparatus 1 may use one first subcarrier pattern and one second subcarrier pattern, or switch between a plurality of first subcarrier patterns and a plurality of second subcarrier patterns. May be used. The subcarrier patterns used by the wireless communication apparatus for data transmission and data reception may be the same or different.

(First modification)
The wireless communication apparatus according to the first embodiment includes a first OFDM modulation unit and a second OFDM modulation unit in a transmission unit, and a first OFDM demodulation unit and a second OFDM demodulation unit in a reception unit, respectively. In the embodiment of the present invention, this configuration is only an example, and a wireless communication apparatus having a different configuration may be used.

  FIG. 9 illustrates a configuration example of a wireless communication apparatus according to the first modification. The transmission unit 10 of the wireless communication apparatus 1 in FIG. 9 includes an OFDM modulation unit 16 and a subcarrier setting unit 17 instead of the first OFDM modulation unit and the second OFDM modulation unit. The receiving unit 20 of the wireless communication device 1 in FIG. 9 includes an OFDM demodulating unit 26 and a subcarrier setting unit 27 instead of the first OFDM demodulating unit and the second OFDM demodulating unit.

  The OFDM modulation unit 16 performs OFDM modulation using a plurality of subcarrier patterns including a first subcarrier pattern and a second subcarrier pattern. The subcarrier setting unit 17 receives a command transmitted from the control unit 40 and sets a subcarrier pattern used by the OFDM modulation unit 16 in OFDM modulation. The OFDM demodulator 26 demodulates OFDM signals related to a plurality of subcarrier patterns including the first subcarrier pattern and the second subcarrier pattern. The subcarrier setting unit 27 receives the command transmitted from the control unit 40 and sets the subcarrier pattern of the OFDM signal demodulated by the OFDM demodulation unit 26.

  In the example of FIG. 9, the transmission unit and the reception unit have separate subcarrier setting units, but a configuration in which both the OFDM modulation unit and the OFDM demodulation unit are set by one subcarrier setting unit may be used. The functions related to the other components are the same as those of the wireless communication apparatus according to the first embodiment.

(Second Embodiment)
The wireless communication apparatus according to the first embodiment includes one transmission unit. However, the wireless communication apparatus according to the embodiment of the present invention may include a plurality of transmission units or a plurality of antennas. In the second embodiment, a method for improving communication quality by reducing interference between radio signals transmitted from each antenna in a radio communication apparatus including a plurality of combinations of transmission antennas and transmission units will be described. .

  FIG. 10 shows a configuration example of a wireless communication apparatus according to the second embodiment. The configuration of the wireless communication device 1 in FIG. 10 is substantially equal to the configuration in which two wireless communication devices according to the first embodiment are arranged in parallel. That is, the wireless communication device 1 of FIG. 10 includes a first transmission unit 10a and a second transmission unit 10b, and a first reception unit 20a and a second reception unit 20b. Since each of the first transmitter 10a and the second transmitter 10b includes separate transmitting antennas (antenna # 1 and antenna # 2), it is possible to transmit radio signals simultaneously from a plurality of antennas.

  The wireless communication device 1 in FIG. 10 includes a MIMO signal generation unit 35. The MIMO signal generation unit 35 divides the transmission target data received by the host interface 30 from the computer 2 into a plurality of data streams. The MIMO signal generation unit 35 includes data output units 35a and 35b as internal components. The data output unit 35a transfers the first data stream to the first transmission unit 10a. Similarly, the data output unit 35a transfers the second data stream to the second transmission unit 10b.

  When MIMO (Multiple-input and multiple-output) communication is performed in data transmission, the transmission destination of the wireless communication device 1 may be one wireless communication device (single user MIMO) or a plurality of wireless communication devices. It may be a device (multi-user MIMO). Further, the wireless communication apparatus 1 may perform processing such as channel estimation, channel correction, and precoding using a pilot signal.

  Note that the wireless communication apparatus 1 does not necessarily perform MIMO communication. In this case, when the transmission target data is transferred from the host interface 30, the MIMO signal generation unit 35 outputs the data to one of the data output units 35a and 35b, and performs a process of dividing the data into a plurality of data streams. Do not execute.

  The functions of the other components related to the wireless communication apparatus 1 in FIG. 10 are the same as those in the first embodiment. In the example of FIG. 10, the same configuration as that in which two wireless communication devices according to the first embodiment are arranged in parallel is shown, but three or more wireless communication devices according to the first embodiment are arranged in parallel. You may use the radio | wireless communication apparatus provided with the structure equal to what was done.

  FIG. 11 illustrates an example of a subcarrier pattern in an OFDM signal transmitted from the wireless communication apparatus according to the second embodiment. The horizontal axis in the upper part of FIG. 11 and the lower part of FIG. 11 indicates the frequency. The upper part of FIG. 11 shows a subcarrier pattern 61a transmitted from the antenna # 1 of the first transmission unit 10a. In the lower part of FIG. 11, subcarrier pattern 61b transmitted from antenna # 2 of second transmitter 10b is shown.

  In the subcarrier pattern 61a and the subcarrier pattern 61b of FIG. 11, the effective subcarriers are distributed in the same pattern in the frequency direction. In such a case, interference is likely to occur between the OFDM signal (wireless signal) transmitted from the antenna # 1 and the OFDM signal (wireless signal) transmitted from the antenna # 2, and the communication quality may be deteriorated. is there.

  Note that when the wireless communication apparatus 1 performs MIMO communication, even if a subcarrier pattern as shown in FIG. 11 is used in OFDM modulation, each subcarrier can be detected by detecting channel distortion that varies depending on the propagation path. The signal being conveyed can be separated and the data can be decoded. However, even with MIMO communication, if the interference between radio signals becomes strong, the throughput in data transmission may not be sufficiently increased.

  When transmitting OFDM signals (radio signals) simultaneously from a plurality of antennas, it is required to suppress interference. In the following, when the wireless communication apparatus transmits OFDM signals (wireless signals) simultaneously from a plurality of antennas, a subcarrier pattern used for suppressing interference between OFDM signals (between wireless signals) is a third subcarrier pattern. It shall be called. The first subcarrier pattern and the second subcarrier pattern in the first embodiment may also serve as the third subcarrier pattern.

  FIG. 12 shows a first example of the third subcarrier pattern. The horizontal axis in the upper part of FIG. 12 and the lower part of FIG. 12 indicates the frequency. The upper part of FIG. 12 shows a third subcarrier pattern 75a transmitted from antenna # 1 of first transmission unit 10a. The lower part of FIG. 12 shows a third subcarrier pattern 75b transmitted from antenna # 2 of second transmission unit 10b.

  Comparing the third subcarrier pattern 75a and the third subcarrier pattern 75b, the distribution of null subcarriers in the frequency band sandwiched between the effective subcarrier of the highest frequency and the effective subcarrier of the lowest frequency is different. Yes. Thus, if the arrangement of at least one or more null subcarriers in the frequency band sandwiched between the effective subcarrier of the highest frequency and the effective subcarrier of the lowest frequency is different, transmission is performed from antenna # 1. Interference between the OFDM signal (radio signal) transmitted from the antenna and the OFDM signal (radio signal) transmitted from the antenna # 2 can be suppressed, and communication quality can be improved.

  Note that, in the radio communication apparatus according to the second embodiment, the subcarrier patterns 61a and 61b in FIG. 11 may be set as the first subcarrier pattern. When the condition of the propagation path is deteriorated or the communication quality is lowered, the subcarrier pattern used for data transmission may be switched to the third subcarrier patterns 75a and 75b in FIG. That is, the third subcarrier pattern exemplified in this embodiment may be used as the second subcarrier pattern in the first embodiment.

  FIG. 13 shows a second example of the third subcarrier pattern. The horizontal axis in the upper part of FIG. 13 and the lower part of FIG. 13 indicates the frequency. The upper part of FIG. 13 shows a third subcarrier pattern 76a transmitted from antenna # 1 of first transmission unit 10a. The lower part of FIG. 13 shows a third subcarrier pattern 76b transmitted from antenna # 2 of second transmission unit 10b.

Since the effective subcarriers are distributed and arranged in the frequency band [f ₁ , f ₂ ] in the third subcarrier patterns 76a and 76b, the frequency diversity effect can be enhanced. Also, since the arrangement pattern of null subcarriers (effective subcarriers) in third subcarrier pattern 76a is different from the arrangement pattern of null subcarriers (effective subcarriers) in third subcarrier pattern 76b, transmission is performed from antenna # 1. Interference between the received OFDM signal (wireless signal) and the OFDM signal (wireless signal) transmitted from the antenna # 2 can be suppressed, and communication quality can be improved. Further, the third subcarrier patterns 76a and 76b may be used as the second subcarrier pattern in the first embodiment.

  FIG. 14 shows a third example of the third subcarrier pattern. The horizontal axis in the upper part of FIG. 14 and the lower part of FIG. 14 indicates the frequency. The upper part of FIG. 14 shows a third subcarrier pattern 77a transmitted from antenna # 1 of first transmission unit 10a. The lower part of FIG. 14 shows a third subcarrier pattern 77b transmitted from antenna # 2 of second transmission unit 10b.

In each of the third subcarrier patterns 77a and 77b, effective subcarriers are regularly arranged in the frequency direction in a part of the frequency band [f ₁ , f ₂ ]. In the third subcarrier pattern 77a, patterns of null subcarriers, effective subcarriers, and effective subcarriers are periodically arranged. In the third subcarrier pattern 77b, patterns of effective subcarriers, effective subcarriers, and null subcarriers are periodically arranged. The third subcarrier patterns 77a and 77b may be used as the second subcarrier pattern in the first embodiment.

  FIG. 15 shows a fourth example of the third subcarrier pattern. The horizontal axis in the upper part of FIG. 15 and the lower part of FIG. 15 indicates the frequency. The upper part of FIG. 15 shows a third subcarrier pattern 78a transmitted from antenna # 1 of first transmission unit 10a. The lower part of FIG. 15 shows a third subcarrier pattern 78b transmitted from the antenna # 2 of the second transmitter 10b.

In the third subcarrier patterns 78a and 78b, effective subcarriers are regularly arranged in the frequency direction within the frequency band [f ₁ , f ₂ ]. In the third subcarrier pattern 78a, patterns of two null subcarriers and two effective subcarriers are repeatedly arranged. In the third subcarrier pattern 78b, patterns of two effective subcarriers and two null subcarriers are repeatedly arranged.

  In the example of FIG. 15, since effective subcarriers are dispersed in a wider frequency band than in the example of FIG. 14, it is easy to enhance the frequency diversity effect. Also, since there is no overlap in the subcarriers used as effective subcarriers in the third subcarrier patterns 78a and 78b, the OFDM signal (radio signal) transmitted from antenna # 1 and the OFDM signal transmitted from antenna # 2 Interference with (radio signal) can be greatly reduced. The third subcarrier patterns 78a and 78b may be used as the second subcarrier pattern in the first embodiment.

  FIG. 16 shows a fifth example of the third subcarrier pattern. The horizontal axis in the upper part of FIG. 16 and the lower part of FIG. 16 indicates the frequency. The upper part of FIG. 16 shows a third subcarrier pattern 79a transmitted from antenna # 1 of first transmission unit 10a. The lower part of FIG. 16 shows a third subcarrier pattern 79b transmitted from antenna # 2 of second transmission unit 10b.

In the third subcarrier patterns 79a and 79b, effective subcarriers and null subcarriers are alternately and periodically distributed in the frequency band [f ₁ , f ₂ ]. Also in the example of FIG. 16, since effective subcarriers are dispersed in a wide frequency band, it is easy to enhance the frequency diversity effect. Similarly to the example of FIG. 15, since there is no overlap in the subcarriers used as effective subcarriers in the third subcarrier patterns 79a and 79b, the OFDM signal (radio signal) transmitted from the antenna # 1 and the antenna Interference with the OFDM signal (radio signal) transmitted from # 2 can be greatly reduced. The third subcarrier patterns 79a and 79b may be used as the second subcarrier pattern in the first embodiment.

  When effective subcarriers are regularly or periodically arranged in the frequency direction as in the examples of FIGS. 14 to 16, the configuration of an electronic circuit, software, or the like can be simplified, and the manufacturing cost of the wireless communication device 1 can be simplified. Can be lowered.

  In radio signals (OFDM signals) transmitted from a plurality of antennas, settings may be made so that effective subcarriers are not arranged on overlapping subcarriers.

  FIG. 17 shows a sixth example of the third subcarrier pattern. The horizontal axis in the upper part of FIG. 17 and the lower part of FIG. 17 indicates the frequency. In the upper part of FIG. 17, a third subcarrier pattern 80a transmitted from antenna # 1 of first transmission unit 10a is shown. The lower part of FIG. 17 shows a third subcarrier pattern 80b transmitted from antenna # 2 of second transmission unit 10b.

  In the third subcarrier patterns 80a and 80b, the arrangement of effective subcarriers (null subcarriers) in OFDM signals (radio signals) transmitted from different antennas is mutually exclusive. That is, settings are made so that effective subcarriers (null subcarriers) are not arranged on subcarriers that overlap in each OFDM signal.

  Although FIG. 17 shows a case where there are two transmitting antennas, a configuration is used in which effective subcarriers are not arranged on subcarriers that overlap between OFDM signals even when there are three or more transmitting antennas. be able to. FIG. 18 shows a seventh example of the third subcarrier pattern. FIG. 18 shows an example in which the arrangement of effective subcarriers (null subcarriers) in an OFDM signal (radio signal) is mutually exclusive in a radio communication apparatus having four transmission antennas. Yes. Referring to the third subcarrier patterns 81a to 81d, only one of the subcarrier patterns has an effective subcarrier arranged in each subcarrier.

  The control unit 40 manages the arrangement of effective subcarriers in the OFDM signal transmitted from each transmission unit (transmission antenna) so that interference caused by the use of the same subcarrier in a plurality of radio signals is prevented. OFDM modulation can be set. When such a configuration is used, since interference between OFDM signals (radio signals) transmitted from a plurality of antennas is suppressed, communication quality can be further improved.

  Here, the case where there is an overlap between subcarriers in which effective subcarriers (null subcarriers) are arranged in OFDM signals (wireless signals) transmitted from a plurality of antennas included in the wireless communication device has been described. . From the viewpoint of suppressing interference and improving communication quality, it is preferable to set the OFDM signal as in the former case. Also, due to circumstances such as the number of antennas in the wireless communication device being large or the number of usable subcarriers being small, it overlaps with subcarriers in which effective subcarriers (null subcarriers) are arranged in OFDM signals (wireless signals). If this occurs, it is desirable to set the respective OFDM signals so as to reduce duplication.

(Second modification)
FIG. 10 described above shows a configuration example of the wireless communication apparatus according to the second embodiment. The wireless communication apparatus according to the embodiment of the present invention may have a different configuration. Below, the radio | wireless communication apparatus which concerns on a different structure from FIG. 10 is demonstrated.

  FIG. 19 illustrates a configuration example of a wireless communication apparatus according to a second modification example provided with a subcarrier setting unit. The first transmission unit 10a of the wireless communication apparatus 1 of FIG. 19 includes an OFDM modulation unit 16a that can perform OFDM modulation with a plurality of subcarrier patterns instead of the first OFDM modulation unit and the second OFDM modulation unit. In addition, the second transmission unit 10b of the wireless communication device 1 of FIG. 19 includes an OFDM modulation unit 16b that can perform OFDM modulation with a plurality of subcarrier patterns instead of the first OFDM modulation unit and the second OFDM modulation unit. Yes.

  19 includes a subcarrier setting unit 17 that can set the subcarrier patterns of the OFDM modulation units 16a and 16b. When receiving the subcarrier pattern change command from the control unit 40, the subcarrier setting unit 17 changes the subcarrier pattern of the OFDM modulation unit 16a or the OFDM modulation unit 16b.

  The functions of the other components of the wireless communication apparatus according to the second modification are the same as those of the wireless communication apparatus according to the second embodiment.

(Third Modification)
19 and 20, the data stream output from the data output unit 35a is input to the first transmission unit 10a, and the data stream output from the data output unit 35b is the second transmission unit 10b. There was a corresponding relationship of being input to. However, the same component may input a data stream to the first transmitter 10a and the second transmitter 10b.

  FIG. 20 illustrates a configuration example of a wireless communication apparatus according to the third modification. The wireless communication device 1 in FIG. 20 does not include the data output units 35a and 35b (MIMO signal generation unit 35). The transmission target data received by the host interface 30 from the computer 2 is subjected to OFDM modulation by at least one of the first transmission unit 10a and the second transmission unit 10b, and transmitted to the transmission destination wireless communication apparatus.

  Functions of other components of the wireless communication apparatus according to the third modification are the same as those of the wireless communication apparatus according to the second embodiment.

(Fourth modification)
In the configuration of FIG. 20, the subcarrier used in OFDM modulation in each transmission unit may be changed using the subcarrier setting unit. FIG. 21 illustrates a configuration example of a wireless communication device according to a fourth modification.

  The first transmission unit 10a of the wireless communication device 1 in FIG. 21 includes an OFDM modulation unit 16a capable of performing OFDM modulation with a plurality of subcarrier patterns. In addition, the second transmission unit 10b of the wireless communication device 1 in FIG. 21 includes an OFDM modulation unit 16b capable of performing OFDM modulation with a plurality of subcarrier patterns. When receiving the subcarrier pattern change command from the control unit 40, the subcarrier setting unit 17 changes the subcarrier pattern of the OFDM modulation unit 16a or the OFDM modulation unit 16b. The functions of the other components of the wireless communication device 1 in FIG. 21 are the same as those of the wireless communication device in FIG.

(Fifth modification)
A wireless communication device including a plurality of transmitting antennas may use a common primary modulation unit. FIG. 22 illustrates a configuration example of a wireless communication apparatus according to the fifth modification, which includes one primary modulation unit.

  The wireless communication device 1 in FIG. 22 includes one transmission unit 10. Data to be transmitted received by the host interface 30 from the computer 2 is input to the primary modulation unit 11. After the primary modulation of the data, the primary modulation unit 11 inputs the signal after the primary modulation to any of the first OFDM modulation unit 12a, the first OFDM modulation unit 12b, the second OFDM modulation unit 13a, and the second OFDM modulation unit 13b. To do. Functions of other components of the wireless communication device 1 in FIG. 22 are the same as those of the wireless communication device in FIG.

(Sixth Modification)
In the configuration of FIG. 22, a subcarrier pattern used in OFDM modulation in each transmission unit may be changed using a subcarrier setting unit. FIG. 23 shows a configuration example of a wireless communication apparatus according to the sixth modification.

  The transmission unit 10 of the wireless communication apparatus 1 in FIG. 22 includes an OFDM modulation unit 16a and an OFDM modulation unit 16b that can perform OFDM modulation with a plurality of subcarrier patterns. When receiving the subcarrier pattern change command from the control unit 40, the subcarrier setting unit 17 changes the subcarrier pattern of the OFDM modulation unit 16a or the OFDM modulation unit 16b. The functions of the other components of the wireless communication device 1 in FIG. 21 are the same as those of the wireless communication device in FIG.

(Third embodiment)
In each of the above embodiments, a plurality of arrangement patterns of effective subcarriers and null subcarriers have been described. Since the attribute of each subcarrier in the OFDM signal is set to either an effective subcarrier or a null subcarrier, it is possible to transmit information using a binary subcarrier attribute. In the third embodiment, a wireless communication apparatus that performs information transmission using a subcarrier pattern will be described.

  Information transmission can be performed using only a subcarrier pattern related to an OFDM signal transmitted from one antenna, or information transmission can be performed by combining subcarrier patterns related to OFDM signals transmitted from a plurality of antennas. it can. In the following, after information transmission by the former method (first method) is described first, information transmission by the latter method (second method) will be described.

In the information transmission by the first method, each of the N subcarriers included in the frequency band [f ₁ , f ₂ ] is regarded as an information bit. For example, subcarrier # 1 is used as bit # 1, subcarrier # 2 is used as bit # 2, and subcarrier # 3 is used as bit # 3. When the subcarrier is an effective subcarrier, the bit value corresponding to the subcarrier is 1; when the subcarrier is the null subcarrier, the bit value corresponding to the subcarrier is 0. Can do. In the rule for converting a bit string into a subcarrier pattern, the correspondence relationship between the bit value and the attribute of the subcarrier may be set to a reverse relationship to the above.

  The maximum number of bits that can be transmitted by the subcarrier pattern related to the OFDM signal transmitted from one antenna is equal to the subcarrier division number N. In addition, when using the radio | wireless communication apparatus provided with the some antenna, the bit number which can be transmitted by a subcarrier pattern can be increased.

In information transmission according to the second method, information bits are expressed using combinations of subcarrier attributes in OFDM signals transmitted from a plurality of antennas. Also in the second method, it is assumed that the frequency band [f ₁ , f ₂ ] of the OFDM signal is divided into N subcarriers. First, consider a case where an OFDM signal having a subcarrier pattern as shown in FIG. 17 is transmitted from each of antenna # 1 and antenna # 2.

  For example, if the attribute of subcarrier # 1 transmitted from antenna # 1 is a valid subcarrier and the attribute of subcarrier # 1 transmitted from antenna # 2 is a null subcarrier, the value of bit # 1 Is assumed to be 0. Similarly, when the attribute of subcarrier # 1 transmitted from antenna # 1 is a null subcarrier and the attribute of subcarrier # 1 transmitted from antenna # 2 is a valid subcarrier, bit # 1 Is assumed to be 1. The transmission-side wireless communication apparatus can perform information transmission using the subcarrier pattern of the OFDM signal if the above-described rule is shared with the reception-side wireless communication apparatus. In addition, the above-mentioned rule is an example and does not prevent using a different rule.

  Next, consider a case in which a wireless communication apparatus having at least four antennas of antenna # 1, antenna # 2, antenna # 3, and antenna # 4 is used. FIG. 18 described above shows an example of subcarrier patterns of the respective OFDM signals transmitted from the four antennas.

  When there is a subcarrier pattern as shown in FIG. 18, information for 2 bits can be expressed using one subcarrier. For example, when only subcarrier # 1 of antenna # 1 is an effective subcarrier and subcarrier # 1 of another antenna is a null subcarrier, it can be considered that information bit “00” is transmitted. Further, when only subcarrier # 1 of antenna # 2 is an effective subcarrier and subcarrier # 1 of the other antenna is a null subcarrier, it is considered that information bit “01” is transmitted. Similarly, when only subcarrier # 1 of antenna # 3 is an effective subcarrier and subcarrier # 1 of other antennas is a null subcarrier, it is considered that information bit “10” is transmitted. When only subcarrier # 1 of antenna # 4 is an effective subcarrier and subcarrier # 1 of the other antenna is a null subcarrier, it is considered that information bit “11” is transmitted.

  The above-mentioned rule is an example, and does not prevent information transmission using a different rule. The rules described here can be determined even when the number of antennas through which OFDM signals are transmitted is different from the examples of FIGS. However, in order to perform information transmission by the second method, it is necessary to use a wireless communication apparatus that can transmit OFDM signals simultaneously from a plurality of antennas.

  Next, the configuration of the wireless communication apparatus according to the third embodiment will be described.

  FIG. 24 illustrates a configuration example of the wireless communication apparatus according to the third embodiment. The wireless communication device 1 of FIG. 24 includes a first transmission unit 10a and a second transmission unit 10b, similarly to the wireless communication device according to the second embodiment, and uses antenna # 1 and antenna # 2. A plurality of OFDM signals (radio signals) can be transmitted simultaneously. The wireless communication device 1 in FIG. 24 further includes a data superimposing unit 90.

  The data superimposing unit 90 receives data to be transmitted using the subcarrier pattern from the host interfaces 30 and 31 or the control unit 40. The data superimposing unit 90 converts a bit string of data to be transmitted into a corresponding subcarrier pattern based on any of the rules described above. The data superimposing unit 90 notifies the subcarrier pattern to at least either the second OFDM modulation unit 13a or the second OFDM modulation unit 13b. The second OFDM modulators 13a and 13b perform OFDM modulation using the subcarrier pattern.

  By performing such processing, more data can be transferred using the data stream transmitted by the first transmitter 10a and the second transmitter 10b. The data transmitted using the subcarrier pattern may be a control signal or a synchronization signal transmitted from the control unit 40 to another wireless communication device, or identifies the computer 2 or the wireless communication device 1 that is the data transmission source. The information may be information or status information, and the type of data is not particularly limited.

  Note that the functions of the other components of the wireless communication device 1 in FIG. 24 are the same as those of the wireless communication device according to each of the embodiments described above.

(Seventh Modification)
The wireless communication device 1 illustrated in FIG. 24 is only an example of the wireless communication device according to the present embodiment. Information transmission using a subcarrier pattern can be performed using a wireless communication apparatus having a configuration different from the example of FIG. Below, the structure of the radio | wireless communication apparatus which concerns on a some modification is demonstrated.

  FIG. 25 illustrates a configuration example of a wireless communication apparatus according to the seventh modification. The transmission target data received by the host interface 30 of the wireless communication apparatus 1 in FIG. 25 is transmitted by at least one of the first transmission unit 10a and the second transmission unit 10b. The functions of the other components of the wireless communication device 1 in FIG. 25 are the same as those of the wireless communication device in FIG.

(Eighth modification)
The wireless communication apparatus according to the present embodiment may further share other components. FIG. 26 illustrates a configuration example of a wireless communication apparatus according to an eighth modification, which includes one primary conversion unit 11. The wireless communication device 1 in FIG. 26 includes a shared primary conversion unit 11. The functions of the other components of the wireless communication device 1 in FIG. 25 are the same as those of the wireless communication device in FIGS.

(Ninth Modification)
In addition, the radio communication apparatus according to the present embodiment may change the subcarrier pattern used in each OFDM modulation unit using the subcarrier setting unit. FIG. 27 shows a wireless communication apparatus including the subcarrier setting unit 17.

  27 includes an OFDM modulation unit 16a and an OFDM modulation unit 16b that can perform OFDM modulation with a plurality of subcarrier patterns. When the subcarrier setting unit 17 receives a subcarrier pattern change command from the control unit 40 or the data superimposing unit 90, the subcarrier setting unit 17 changes the subcarrier pattern of the OFDM modulation unit 16a or the OFDM modulation unit 16b. The functions of the other components of the wireless communication device 1 in FIG. 27 are the same as those of the wireless communication device in FIG.

(10th modification)
FIG. 28 is a wireless communication apparatus according to a configuration in which the host interface of the wireless communication apparatus in FIG. 27 is shared. The transmission target data received by the host interface 30 of the wireless communication device 1 in FIG. 28 is transmitted by at least one of the first transmission unit 10a and the second transmission unit 10b. The functions of the other components of the wireless communication device 1 in FIG. 29 are the same as those of the wireless communication device in FIG.

(Eleventh modification)
FIG. 28 shows a wireless communication apparatus according to the eleventh modification. In the wireless communication device 1 of FIG. 28, the primary modulation unit 11 is shared. Further, the subcarrier pattern used in each OFDM modulation unit is changed using the subcarrier setting unit.

  In the above description, the wireless communication apparatus according to a plurality of configurations has been described. However, wireless communication apparatuses having other configurations may be used. In each of the above-described embodiments, the radio communication apparatus using OFDM modulation has been described, which can achieve good communication quality while maintaining the frequency diversity effect even when the propagation path condition is deteriorated. Further, even when data transmission is performed simultaneously using a plurality of antennas by MIMO communication or the like, it is possible to suppress interference between radio signals (OFDM signals) and prevent deterioration in communication quality. Furthermore, by utilizing a subcarrier pattern in OFDM modulation, the amount of data that can be transmitted by the wireless communication apparatus can be increased.

  The radio communication apparatus according to the embodiment of the present invention can be applied to, for example, a cellular network system, a backhaul line, and a fronthaul line, but may be applied to any type of radio communication system.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. Further, for example, a configuration in which some components are deleted from all the components shown in each embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

1, 1a, 1b Wireless communication device 2, 2a, 2b Computer 5a, 5b Network 10 Transmitter 10a First transmitter 10b Second transmitter 11, 11a, 11b Primary modulator 12, 12a, 12b First OFDM modulator 13 , 13a, 13b Second OFDM modulators 14, 14a, 14b D / A converters 15, 15a, 15b Transmit amplifiers 16, 16a, 16b OFDM modulators 17, 27 Subcarrier setting unit 20 Receiver 20a First receiver 20b Second Receiver 21 Low noise amplifier 22 A / D converter 23 First OFDM demodulator 24 Second OFDM demodulator 25 Primary demodulator 26 OFDM demodulator 30, 31 Host interface 35 MIMO signal generator 35a, 35b Data output unit 40 Control unit 51 , 52, 51a, 51b, 52a, 52b Antenna 60 First sub Carrier patterns 70, 71, 72, 73, 74 Second subcarrier patterns 61a, 61b Subcarrier patterns 75a, 75b, 76a, 76b, 77a, 77b, 78a, 78b, 79a, 79b, 80a, 80b, 81a, 81b, 81c, 81d Third subcarrier pattern 90 Data superimposing unit

Claims (19)

A first subcarrier pattern that defines the distribution of effective subcarriers and null subcarriers in a predetermined frequency band, or a distribution of effective subcarriers and null subcarriers, in which null subcarriers are present more than the first subcarrier pattern. A radio communication apparatus including a transmission unit that selects one of a plurality of second subcarrier patterns and transmits a first radio signal that is OFDM-modulated based on the selected subcarrier pattern. The transmission unit is configured to perform the first subcarrier pattern or the second in OFDM modulation of the first radio signal based on communication quality in a propagation path with a radio communication device that is a transmission destination of the first radio signal. Decide which subcarrier pattern to use,
The wireless communication apparatus according to claim 1. The communication quality is at least one of an error rate, a transmission rate, and a signal-to-noise ratio.
The wireless communication apparatus according to claim 2. The transmitter determines whether to use the first subcarrier pattern or the second subcarrier pattern in OFDM modulation of the first radio signal based on weather information;
The wireless communication apparatus according to any one of claims 1 to 3. Subcarrier information indicating whether the second radio signal is OFDM-modulated based on either the first subcarrier pattern or the second subcarrier pattern is received from another radio communication apparatus, and the subcarrier information 5. The wireless communication device according to claim 1, further comprising: a receiving unit that performs OFDM demodulation on the received second wireless signal based on the base station. The subcarrier information includes information on the distribution of the effective subcarriers in the first subcarrier pattern or the distribution of the effective subcarriers in the second subcarrier pattern.
The wireless communication apparatus according to claim 5. All the effective subcarriers in the second subcarrier pattern are distributed within the predetermined frequency band.
The wireless communication apparatus according to any one of claims 1 to 6. The second subcarrier pattern has at least two null subcarriers that are not adjacent to each other in the frequency direction between the effective subcarrier having the highest frequency and the effective subcarrier having the lowest frequency.
The wireless communication apparatus according to any one of claims 1 to 7. The effective subcarriers in the second subcarrier pattern are periodically or regularly distributed in the frequency direction.
The wireless communication apparatus according to any one of claims 1 to 8. A plurality of the transmission units;
The first radio signal transmitted by the antenna of the transmission unit has a distribution of a plurality of the null subcarriers between the effective subcarrier having the highest frequency and the effective subcarrier having the lowest frequency. OFDM modulated so as not to be the same as the first radio signal transmitted by the antenna of the transmission unit,
The wireless communication apparatus according to any one of claims 1 to 9. The first radio signal transmitted by the antenna of the transmitter does not overlap with the first radio signal transmitted by the antenna of the other transmitter in the subcarrier set as the effective subcarrier. OFDM modulated to
The wireless communication apparatus according to claim 10. The transmitter performs information transmission using the first subcarrier pattern or the second subcarrier pattern in OFDM modulation of the first radio signal.
The wireless communication apparatus according to any one of claims 1 to 11. As a subcarrier pattern used for OFDM modulation of the first radio signal, a first subcarrier pattern defining a distribution of effective subcarriers and null subcarriers in a predetermined frequency band, or a distribution of effective subcarriers and null subcarriers. Selecting one of a second subcarrier pattern that has more null subcarriers than the first subcarrier pattern, and
Transmitting subcarrier information including information related to the selected subcarrier pattern;
Transmitting the first radio signal that is OFDM-modulated based on the subcarrier pattern;
Wireless communication method. The wireless communication device that has received the first wireless signal includes a step of OFDM demodulating the first wireless signal based on the subcarrier information.
The wireless communication method according to claim 13. Based on the communication quality in the received second radio signal, select either the first subcarrier pattern or the second subcarrier pattern as a subcarrier pattern used for OFDM modulation of the first radio signal.
The wireless communication method according to claim 13 or 14. Based on weather information, selecting either the first subcarrier pattern or the second subcarrier pattern as a subcarrier pattern to be used for OFDM modulation of the first radio signal,
The wireless communication method according to any one of claims 13 to 15. Distribution of the plurality of null subcarriers between the effective subcarrier of the highest frequency and the effective subcarrier of the lowest frequency of the first radio signal transmitted from the plurality of antennas is the other antenna. OFDM modulation so as not to be the same as the first radio signal transmitted by
The wireless communication method according to any one of claims 13 to 16. OFDM modulating the first radio signal transmitted from a plurality of antennas so that the first radio signal transmitted by another antenna and the subcarrier set as the effective subcarrier do not overlap. including,
The wireless communication method according to any one of claims 13 to 17. Information transmission is performed using the selected subcarrier pattern.
The wireless communication method according to any one of claims 13 to 18.

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