JP7140907B2 - wireless communication device - Google Patents

Description

The present invention relates to a wireless communication device that transmits multiple pieces of data by hierarchical division multiplexing.

In the fifth-generation communication, a communication method using a wide bandwidth for increasing throughput has become mainstream. On the other hand, the current carrier frequency band is tight and it is difficult to secure a wide frequency band. For this reason, it has been proposed to use a submillimeter wave or millimeter wave frequency band in which it is easy to secure a wide frequency band. Since the free space loss is large in such a high frequency band, in order to expand the communication area, "Massive MIMO" forms a pencil beam with a large antenna gain by using multiple antennas and controlling their phases. Or "Phased Array" technology is often used.

In the field of broadcasting, ATSC (Advanced Television Systems Committee standards) 3.0, which is the next-generation digital terrestrial broadcasting standard in the United States, provides two different services: Upper Layer (UL) and Lower Layer (UL). LL), and the UL and LL are multiplexed at different power ratios and transmitted. This technology is called layered division multiplexing (LDM) (see Non-Patent Documents 1 and 2). In cellular communication, a similar technique is used as a system called NOMA (Non Orthogonal Multiplexing Access).

Schematic configurations of conventional LDM transmitters and LDM receivers will be described below.
FIG. 12 is a diagram showing an example of functional blocks of a conventional LDM transmitter. As shown in FIG. 12, the conventional LDM transmission device includes a UL data processing unit 100, an LL data processing unit 101, a combining unit 124, and an OFDM (Orthogonal Frequency Division Multiplexing) modulation unit 125. , and a transmit antenna 126 .

The UL data processing section 100 processes UL data, and includes a UL error correction coding section 121U, a UL carrier modulation section 122U, and a power adjustment section 123U. Similarly, the LL data processing unit 101 that processes LL data includes an LL error correction coding unit 121L, an LL carrier modulation unit 122L, and a power adjustment unit 123L.

The operation of a conventional LDM transmitter will be described.
The UL information bits are input to the UL error correction coding unit 121U of the UL data processing unit 100, and are subjected to predetermined error correction coding by the UL error correction coding unit 121U. After that, in the UL carrier modulation unit 122U, quadrature amplitude modulation (QAM), PSK (Phase Shift Keying), or non-uniform quadrature amplitude modulation (Non Uniform QAM), such as a modulation method that maps to the IQ plane It is modulated by a digital modulation method. Then, the transmission power of the modulated UL signal is adjusted by power adjusting section 123U so as to achieve a predetermined power ratio between UL and LL, and input to combining section 124 .

In LL, which transmits information different from UL, information bits are input to LL data processing section 101, error correction encoded by LL error correction encoding section 121L, and carrier modulated by LL carrier modulation section 122L. Then, power adjustment section 123 L adjusts the transmission power, and the result is input to combining section 124 .

The error correction encoding performed by the UL error correction encoding unit 121U and the LL error correction encoding unit 121L may be the same error correction encoding scheme or different schemes. The carrier modulation method in the UL carrier modulating section 122U and the LL carrier modulating section 122L modulates the UL with 64QAM and the LL with QPSK (Quadrature Phase Shift Keying), or modulates the UL with QPSK and the LL with 64QAM. In general, the transmission power is UL transmission power and LL transmission power, that is, each radiation power of UL and LL (effective radiation power or effective isotropic radiation power), in order to facilitate demodulation processing on the receiving side. It is desirable to provide a difference in

Then, the UL and LL signals are combined in combining section 124 , the combined signal is OFDM-modulated in OFDM modulation section 125 , and output from transmission antenna 126 as a transmission signal. Thus, the operation of a conventional LDM transmitter is performed.

Next, the configuration of a conventional LDM receiver will be explained using FIG. FIG. 13 is a diagram showing an example of functional blocks of a conventional LDM receiver. As shown in FIG. 13, the conventional LDM receiver includes a receiving antenna 130, an OFDM demodulator 131, a UL carrier demodulator 132, a UL error correction decoder 133, a replica generator 134, and a removal processor. 135 , an LL carrier demodulator 136 and an LL error correction decoder 137 .

The operation of a conventional LDM receiver will be described.
In the conventional LDM receiver, the multiplexed transmitted signal is received by the receiving antenna 130 of the receiver, and the OFDM demodulator 131 performs FFT (Fast Fourier Transform) processing and transmission path estimation. Demodulation processing is performed and branched to the UL carrier demodulation unit 132 and removal processing unit 135 . One of the branched signals is subjected to carrier demodulation corresponding to the carrier modulation applied to the UL data on the transmission side in the UL carrier demodulation section 132 .

The carrier-demodulated UL signal is subjected to error correction decoding in UL error correction decoding section 133 corresponding to UL error correction coding section 121U on the LDM transmitting apparatus side, and UL decoded bits are output. At the same time, the UL decoded bits decoded by the UL error correction decoding unit 133 are input to the replica generation unit 134 and subjected to carrier modulation again using the modulation scheme used by the UL carrier modulation unit 122U on the LDM transmission device side. Furthermore, a replica of the UL received signal (UL replica signal) is generated using the channel estimation result and the like.

Then, in removal processing section 135, the UL replica signal is removed from the multiplexed signal from OFDM demodulation section 131, and the LL signal, which is the received LL signal, is extracted. Thereafter, the LL signal is carrier-demodulated in the LL carrier demodulation section 136 in consideration of the UL and LL power ratios in the power adjustment sections 123U and 123L on the LDM transmission device side. The signal from the LL carrier demodulation unit 136 is input to the LL error correction decoding unit 137, error correction decoding corresponding to the LL error correction coding unit 121L on the LDM transmission device side is performed, and LL decoded bits are output. Thus, the operation in the receiving device is performed.

The signal from the OFDM demodulator 131 is in a state in which the UL signal and the LL signal are combined, but assuming that error correction decoding and replica generation are performed accurately, the output of the replica generator 134 is pure UL. The UL signal, which is the received signal, is to be reproduced. Therefore, the LL signal can be extracted by subtracting the UL replica signal from the multiplexed OFDM demodulated signal.

Okada, Shibata, et al., “A Study on Application of LDM System to Terrestrial Digital TV Broadcasting”, Institute of Image Information and Television Engineers Technical Report, 40, 1-4, 2016.10 Sato et al., “A Study on Application of LDM for Next Generation Terrestrial Broadcasting”, Institute of Image Information and Television Engineers Technical Report, vol.41, no.6, BCT2017-34, pp.45-48, February 2017

For example, in cellular systems, when a base station manages multiple terminal stations within its own sector, it is often the case that data signals and control signals are transmitted using separate channels such as different frequencies, resulting in poor frequency utilization efficiency. I had a problem. Moreover, when a plurality of frequencies are used, an RF (Radio Frequency) circuit corresponding to each frequency is required, resulting in an increase in the size of the device.

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional circumstances as described above, and it is an object of the present invention to provide a wireless communication device capable of efficiently transmitting a plurality of different types of data at the same frequency and time. With the goal.

In order to achieve the above object, the present invention configures a wireless communication device as follows.
That is, in a wireless communication device that transmits a plurality of data by hierarchical division multiplexing, a first beam that transmits first data and a second beam that transmits second data different in type from the first data are An antenna that outputs to space at the same frequency and time, a power ratio adjustment unit that adjusts the power ratio of the first beam and the second beam, and a beam width that controls the width of the first beam and the second beam a controller, wherein the beam width controller controls the width of the first beam and the width of the second beam to be different from each other.

In this way, the wireless communication device according to the present invention is configured to transmit the first data and the second data different in type from the first data using beams of different widths in hierarchical division multiplexing. ing. This makes it possible to efficiently transmit a plurality of different types of data at the same frequency and time.

As one configuration example, when the wireless communication device according to the present invention transmits data used for controlling transmission of the first data as the second data, the beam width control unit may control the transmission of the first beam may be controlled to narrow the width of the second beam and widen the width of the second beam.

In this case, the power ratio adjustment unit determines that the radiated power of the first beam is greater than the radiated power of the second beam in the range of the transmission direction of the first beam and the width of the first beam, and You may adjust so that it may become more than a predetermined electric power difference. Alternatively, the power ratio adjustment unit is configured such that, in the range of the transmission direction of the first beam and the width of the first beam, the radiation power of the second beam is greater than the radiation power of the first beam, and a predetermined may be adjusted to be equal to or greater than the power difference of Also, the second data may include location information of the wireless communication device.

Further, the beam width control section may be configured to digitally control the widths of the first beam and the second beam. Further, the beam width control section may be configured to control the widths of the first beam and the second beam in an analog manner. The antenna includes a reflector, a first radiator that radiates radio waves of the first data to the reflector to generate the first beam, and a radio wave of the second data that is radiated to the reflector. and a second radiator for generating the second beam by adjusting the position of the first radiator and the position of the second radiator with respect to the reflecting mirror. , the width of the first beam and the width of the second beam may be controlled.

Also, in the radio communication apparatus according to the present invention, the pilot signal used for demodulating the first data and the pilot signal used for demodulating the second data are orthogonalized in the domain of time, frequency, or code. A configuration may be adopted in which they are arranged in relation to each other and transmitted.

According to the present invention, it is possible to provide a wireless communication device capable of efficiently transmitting a plurality of different types of data at the same frequency and time.

1 is a diagram showing an example of functional blocks of a wireless communication device according to a first embodiment; FIG. FIG. 10 is a diagram showing directivity gain when the beam direction is the front of the antenna; FIG. 10 is a diagram showing directivity gain when the beam direction is tilted from the front of the antenna; FIG. 2 is a diagram for explaining a usage example of the wireless communication device according to the first embodiment; FIG. It is a figure which shows the example of the beam shape of UL and LL in 1st Example. FIG. 4 is a diagram showing an example of a receiving-side constellation in the direction in which the UL antenna gain is maximum; FIG. 4 is a diagram showing an example of a reception-side constellation in a direction in which UL antenna gain is small; FIG. 7 is a diagram illustrating another example of use of the wireless communication device according to the first embodiment; FIG. 10 is a diagram showing an example of UL and LL beam shapes in the second embodiment; It is a figure explaining a general parabolic antenna. It is a figure explaining the parabolic antenna in 3rd Example. FIG. 12 is a diagram for explaining the arrangement of pilot signals in the fourth embodiment; FIG. 1 is a diagram showing an example of functional blocks of a conventional LDM transmitter; FIG. 1 is a diagram showing an example of functional blocks of a conventional LDM receiver; FIG.

A wireless communication device according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows an example of functional blocks of a radio communication apparatus according to the first embodiment of the present invention. The radio communication apparatus of this example includes an upper layer modulation unit 11, a lower layer modulation unit 12, an upper IL (Injection Level) control unit 13, a lower IL control unit 14, an upper layer amplitude/phase control unit 15, A lower layer amplitude/phase control unit 16 , a combining unit 17 , an RF conversion unit 18 and an antenna unit 19 are provided.

Information A and information B are supplied to the wireless communication apparatus of this example from the outside. The information A and the information B are data with different contents, and their transmission rates are often different, as will be described in detail later. Information A is input to the upper hierarchical modulation section 11 and information B is input to the lower hierarchical modulation section 12 .
The upper layer modulation unit 11 subjects the information A to channel encoding and digital modulation processing. Similarly, the lower layer modulation unit 12 subjects the information B to channel encoding and digital modulation processing.

Codes such as convolutional codes, turbo codes, and LDPC (Low Density Parity Check) are often used in channel coding. Alternatively, concatenated coding is often used in which these codes are used as inner codes and codes such as RS (Reed-Solomon) codes and BCH (Bose-Chaudhuri-Hocquenghem) codes are used as outer codes. Since the present invention does not depend on these codes, any code may be adopted.

A single-carrier modulation method, OFDM, or the like is often used for digital modulation processing. In addition, FBMC (Filter Bank Multi-Carrier), GFDM (Generalized Frequency Division Multiplexing), etc. are also under consideration as fifth-generation communication systems. Since the present invention does not greatly depend on these modulation schemes, OFDM, which has become mainstream in recent years, will be used in the following description. In the OFDM system, after performing primary modulation such as QPSK or 16QAM, digital modulation is performed by secondary modulation in which a plurality of subcarriers are orthogonally multiplexed on the frequency axis.

In this manner, the information A is subjected to channel coding and digital modulation processing in the upper layer modulation unit 11 to generate a modulated signal. Similarly, in the lower hierarchical modulation unit 12, the information B is subjected to channel encoding and digital modulation processing to generate a modulated signal. The coding rate of channel coding and the modulation multilevel number of digital modulation in the upper hierarchical modulation unit 11 and the lower hierarchical modulation unit 12 will be described later.

The modulated signal of the information A output from the upper layer modulation section 11 is multiplied by the coefficient α by the upper IL control section 13 and then transmitted to the upper layer amplitude/phase control section 15 . In the upper layer amplitude/phase control unit 15, processing for forming a radiation beam of information A is performed.
Similarly, the modulated signal of the information B output from the lower layer modulation section 12 is multiplied by the coefficient β by the lower layer IL control section 14 and then transmitted to the lower layer amplitude/phase control section 16 . In the lower layer amplitude/phase control unit 16, processing for forming a radiation beam of information B is performed.
In the first embodiment, the coefficients α and β used by the upper IL control unit 13 and the lower IL control unit 14 are described as α=β=0.5. That is, a case will be described in which the UL total transmission power and the LL total transmission power are made equal.

The upper layer amplitude/phase control unit 15 modulates the modulated signal from the upper layer modulation unit 11 with N types (N is a natural number and matches the number of antenna elements that the antenna unit 19 has) of amplitude A _n ( _n is the antenna number, 1≤n≤N) and the result of variably controlling the phase θn is output. A radiation beam is formed by this control, and the shape of the beam also depends on the arrangement of the antenna elements of the antenna section 19 . For example, if the antenna elements are arranged in a line at equal intervals, if each phase (θ ₁ to θ ₆ in FIG. 1) is controlled to be equal, the signal sent from each antenna will be High antenna gain is obtained by in-phase combining in the front direction. At this time, when forming a sharp pencil beam, it is desirable that the amplitudes (A ₁ to A ₆ in FIG. 1) of the upper layer amplitude/phase control section 15 are the same.

FIG. 2 shows the directional gain when the beam direction is the front of the antenna. According to the figure, a high antenna gain is obtained in the front direction, but the antenna gain is lowered in directions other than the front direction. This is because the phases at the time of spatial synthesis are different in directions other than the front, and may be canceled by the opposite phase.

FIG. 3 shows the directional gain when the beam direction is tilted from the front of the antenna. In this way, when it is desired to form a beam in a direction other than the frontal direction, it is sufficient to control the phase (θ ₁ to θ ₆ in FIG. 1) of the upper layer amplitude/phase control section 15 so that in-phase synthesis is performed in a desired direction. .
As described above, by controlling the phase θ _n of the upper layer amplitude/phase control unit 15, it is possible to concentrate energy in a desired direction and perform wireless transmission with good energy efficiency.

Leaving aside the description of the configuration of the wireless communication device, the problem to be solved by this embodiment will be described.
FIG. 4 shows an example in which the wireless communication device shown in FIG. 1 is installed in the base station 21 and the base station 21 and three terminal stations 22 to 24 perform data communication. When the base station 21 wishes to perform data communication with the terminal station 22 (terminal X), the beam forming described above may be performed in that direction. Similarly, when it is desired to perform data communication with another terminal station, a beam can be formed in that direction. Although it depends on the beam shape, in general, when a sharp pencil beam with high antenna gain is formed, data communication cannot be performed at terminal stations other than the terminal station to be communicated because the antenna gain is lowered.

Here, when the base station 21 puts all of these three terminal stations 22 to 24 under control management, it is desirable to notify all the terminal stations of the control information. In cellular communication, the User-Plane for transmitting data signals and the Control-Plane for transmitting control signals are set to different frequencies, and control signals are notified using a communication line different from that for data signals. There are many.

For example, as an example of communication of data signals and control signals, when the base station 21 communicates with all of the terminal stations 22 to 24, according to some scheduling rule (the scheduling method is not specified), each terminal station Consider performing data communication while forming directed beams in a time division manner. At this time, while data communication is being performed with a certain terminal station, control information such as schedule information is also notified to other terminal stations, and timing synchronization is performed with terminal stations that are not subject to data communication. It is possible to communicate more efficiently.

In the first embodiment, by providing a hierarchical division multiplexing radio communication apparatus that beamforms data signals for a specific terminal station and control signals for a plurality of terminal stations as described above so that they can be communicated on the same frequency. , improve frequency utilization efficiency and simplify the system.
A method of realizing, on the same frequency, an upper layer in which data communication is performed while forming beams, and a lower layer in which control signals are broadcasted to a plurality of terminal stations, which is the main focus of the present invention, will be described below.

As described above, the data signal is transmitted while being beam-formed using the upper layer modulation section 11 and the upper layer amplitude/phase control section 15 .
On the other hand, the control signal is transmitted while being beam-formed using the lower hierarchical modulation section 12 and the lower hierarchical amplitude/phase control section 16 . When the same control information is transmitted to all the terminal stations 22 to 24 in FIG. 4, the communication is of broadcast type.

In general, the control signal has a lower transmission rate than the data signal. Therefore, by lowering the coding rate of the lower hierarchical modulation unit 12 and lowering the modulation multilevel number, even if the received power is low, It is possible to demodulate. For example, the coding rate is 1/3, and BPSK (Binary Phase Shift Keying) is used as the modulation method. Alternatively, in order to further improve stability, it is possible to obtain a diversity effect by transmitting the same data multiple times, and to improve received signal quality.
Conversely, data signals are often required to have high throughput, and high-order multilevel modulation such as 64QAM and 256QAM are used for the modulation multilevel number, and accordingly high reception power (high reception S/N) is required. I need.

The modulated signal generated by the lower layer modulation section 12 is transmitted to the lower layer amplitude/phase control section 16 . The lower layer amplitude/phase control unit 16 forms a broad radiation beam so as to target a plurality of terminal stations. When forming a broad beam, it is better to provide a difference in the amplitudes (B ₁ to B ₆ ) of the lower layer amplitude/phase control section 16 . For example, by setting the _amplitude of only _B3 to _√6 and setting the other _B1 , B2, B4, B5, and _B6 to 0, the normalized power of LL becomes the _same value as that of UL, and the beam is maximized. Can be formed broad. Also, the beam shape formed by the lower layer amplitude/phase control unit 16 does not necessarily have to be broad, and it is possible to narrow the beam width and variably control the beam direction as in the upper layer.

The signal from the upper layer amplitude/phase control section 15 and the signal from the lower layer amplitude/phase control section 16 are combined in the combining section 17 . Here, it is desirable that the modulation signal generation timing of the upper hierarchical modulation section 11 and the modulation signal generation timing of the lower hierarchical modulation section 12 are the same. When an OFDM signal is used, the same symbol timing is used in the upper layer modulation section 11 and the lower layer modulation section 12 .
The signal synthesized by the synthesizing section 17 is converted into an RF signal by the RF converting section 18 and sent out from the antenna section 19 .

Since the RF conversion unit 18 and the antenna unit 19 are analog elements, individual differences in characteristics occur. Therefore, if the upper layer amplitude/phase control unit 15 and the lower layer amplitude/phase control unit 16 obtain these individual differences in advance by some method, and offset the calibration coefficients to reduce the individual differences. good. Since the method for measuring individual differences is not directly related to the present invention, it will not be mentioned here.

FIG. 5 shows an example of UL and LL beam shapes in the first embodiment. In the figure, the beam width of UL (data signal) indicated by a solid line is narrowed, and the beam width of LL (control signal) indicated by a dotted line is widened. Thus, in the radio communication apparatus of the first embodiment, UL and LL are beamformed independently.

Next, processing on the receiving side (for example, terminal stations 22 to 24 in FIG. 4) will be described.
In the case of OFDM, if the timings of the UL signal and the LL signal are perfectly matched, the orthogonality of each subcarrier is maintained for both UL and LL, and the constellation on the receiving side is observed as shown in FIGS. 6A and 6B. be done.

FIG. 6A shows an example of a receiver constellation in the direction of maximum UL antenna gain. It is assumed that the UL signal indicated by the circle is modulated by 16QAM, and the LL signal indicated by the cross is modulated by QPSK. Although only x marks are observed as a constellation, UL signals indicated by ◯ marks can be demodulated from the observed received signals. At this time, the LL signal indicated by the cross acts as noise for the UL signal.

Here, the ratio of UL received power to LL received power will be described.
We set the UL total transmit power and the LL total transmit power to be equal power, and assume LL is the omni-directional antenna gain. In this case, the UL received power is 20 log ₁₀ (N) [dB] larger than the LL received power in the direction in which the UL antenna gain is maximum. Therefore, if the thermal noise generated by the LNA (Low Noise Amplifier) of the receiving unit is sufficiently smaller than the LL received power, the required S/N ratio (Signal-to-Noise ratio) is 20 log ₁₀ (N) [dB ] can be transmitted.

Further, when demodulating the LL signal, as shown in Non-Patent Documents 1 and 2, etc., after the UL signal is demodulated, the LL signal is extracted by generating a replica of the UL signal and subtracting it from the received signal. There is a SIC (Successive Interference Canceller) system that treats UL and LL as one signal, and an MLD (Maximum Likelihood Detection) system that collectively demodulates UL and LL simultaneously. By using these methods, the UL signal (information A) and the LL signal (information B) can be reproduced.

FIG. 6B shows an example of a receive-side constellation in the direction where the UL antenna gain is small. The UL signal indicated by the circle is small, and the LL signal indicated by the cross is received with a relatively large value. The figure shows an example of a terminal station that does not transmit data and receives only control signals, and it is sufficient to demodulate the signals marked with x, which are LL signals. At this time, the UL signal component (marked with a circle) leaking to the LL signal behaves as noise.

Thus, both the UL signal and the LL signal can be demodulated in the direction in which the UL antenna gain is maximized, and only the LL signal can be demodulated in other directions. By doing so, even if the base station manages a plurality of terminal stations within a sector as described above, it is possible to transmit control signals to all terminals at the same time.

Next, another usage example of the wireless communication device according to the first embodiment will be described with reference to FIG. FIG. 7 shows an example in which the wireless communication device shown in FIG. 1 is installed in a base station 31 and a terminal station 32 (for example, a helicopter), and two-way communication is performed while the base station 31 and the moving terminal station 32 follow beams. is shown. The base station 31 and the terminal station 32 communicate with each other using a pencil beam in order to achieve high throughput for data signals. At this time, in order to control the beam in each other's direction, a broad beam is formed on the LL and a control signal including its own position information obtained by a GPS (Global Positioning System) or the like is transmitted. Since it does not matter if the throughput of location information is low, it can be transmitted by a broad beam with a small antenna gain.

Also, transmission of location information by LL is effective even when the terminal station does not move. That is, by broadcasting control information including GPS position information from a base station to all terminal stations, each terminal station can accurately grasp the position of the base station. When transmitting data, it is possible to perform beam control that provides high transmission efficiency.

As described above, the radio communication apparatus according to the first embodiment uses the same frequency for the UL beam for transmitting the data signal and the LL beam for transmitting the control signal used for controlling the transmission of the data signal. And an antenna unit 19 that outputs to space in time, an upper IL control unit 13 and a lower IL control unit 14 that adjust the power ratio of each beam of UL and LL, and an upper layer that controls the width of each beam of UL and LL An amplitude/phase control section 15 and a lower layer amplitude/phase control section 16 are provided. The upper layer amplitude/phase control unit 15 and the lower layer amplitude/phase control unit 16 are configured to narrow the width of the UL beam and widen the width of the LL beam. Further, by the upper IL control unit 13 and the lower IL control unit 14, the radiated power of the UL beam is greater than the radiated power of the LL beam in the transmission direction of the UL beam and the range of the UL beam width, and It is configured to adjust so that the power difference is equal to or greater than a predetermined power difference.

Therefore, by installing the radio communication apparatus according to the first embodiment in a base station, for example, the base station transmits a control signal to all terminals in a sector, and at the same time, a specific terminal station data signals can be transmitted. Also, for example, by transmitting the position information of the wireless communication device as a control signal, it is possible to perform beam control with high transmission efficiency when transmitting data from the terminal station to the base station side. Further, for example, when one or both of the communication partners move, by notifying each other of position information using control signals, two-way communication can be performed while tracking the beam. In this way, it is possible to efficiently transmit a plurality of different types of data with the same frequency and time.

(Second embodiment)
A radio communication apparatus according to a second embodiment of the present invention will be described. In the second embodiment, unlike the first embodiment, a case will be described where a first data signal is assigned to LL and a second data signal different from the first data signal is assigned to UL. As for beam formation, the UL is a sharp pencil beam and the LL is a broad beam, as in the first embodiment.

In a second embodiment, the LL signal is allocated a large total transmit power and the UL signal a small total transmit power. In the first embodiment, the same transmission power of 0.5 [W] is used for both UL and LL, and the total transmission power of UL and LL is set to 1 [W]. For ease of comparison with the first embodiment, the second embodiment also assumes that the total transmission power of UL and LL is 1 [W].

Since a large transmission power is allocated to the LL signal, the coefficient β used in the lower IL control section 14 is set to a larger value than the coefficient α used in the upper IL control section 13 (that is, β>α). Assuming that the relative power difference between LL and UL is γ [dB], the normalized power is 1, so the values of β and α are expressed by the following (equation 1).

Here, in the second embodiment, since the UL signal is beamformed in the same manner as in the first embodiment, it has an antenna gain of 20log ₁₀ (N) [dB]. FIG. 8 shows examples of UL and LL beam shapes in the second embodiment. In the figure, the beam width of UL (first data signal) indicated by a solid line is narrowed, and the beam width of LL (first data signal) indicated by a dotted line is widened. Thus, in the radio communication apparatus of the second embodiment, UL and LL are beamformed independently.

LL power is γ [dB] larger than UL, and UL has an antenna gain of 20 log ₁₀ (N) [dB], so the power difference between LL and UL is γ-20 log ₁₀ (N) [dB] . As shown in FIG. 8, the broad beamwidth LL signal indicated by the dashed line allows the second data signal to be broadcast with high throughput. In this case, a high-order modulation multilevel number such as 64QAM or 256QAM is suitable for the LL modulation multilevel number.

In addition, by the UL signal of the pencil beam shown by the solid line, the first data can be transmitted to the terminal in the specific direction in addition to the broadcast transmission of the second data. In this case, it is desirable to use a lower-order modulation multilevel number than LL, such as 16QAM, as the UL modulation multilevel number.

As described above, the radio communication apparatus according to the second embodiment uses the upper IL control unit 13 and the lower IL control unit 14 to radiate the LL beam in the transmission direction of the UL beam and the range of the UL beam width. The power is adjusted so that it is greater than the radiation power of the UL beam and equal to or greater than a predetermined power difference. By performing such control, in addition to the broadcast transmission, it becomes possible to transmit other data with a relatively high throughput to the other party in a specific direction.

(Third embodiment)
A radio communication apparatus according to a third embodiment of the present invention will be described. In the first and second embodiments, the UL and LL are synthesized by the synthesizing unit 17 by digital processing. On the other hand, the third embodiment has a configuration in which UL and LL are combined in an analog circuit or spatially combined after antenna output. That is, in the radio communication apparatus according to the third embodiment, instead of the configuration in which the widths of the UL and LL beams are digitally controlled as in the first and second embodiments, the widths of the UL and LL beams are controlled. is controlled by an analog method.

In the case of digital synthesis, when the number of antenna elements N increases (for example, when N>32), there is a problem that the scale of the device increases. This problem can be solved by using a hybrid configuration of digital and analog beamforming, or a configuration of analog beamforming only. Hierarchical division multiplexing transmission that forms different beams, which is the main focus of the present invention, does not depend on beam forming methods such as digital beam forming and analog beam forming, so any beam forming method may be used. In the case of beam scanning, a lens antenna for beam scanning or a mechanical beam scanning antenna may be used.

Beam control when using a parabolic antenna will be described below. In this case, the beam width can be controlled by changing the focal point of the parabolic antenna.
A general parabolic antenna includes a radiator 41 and a reflector 42, as shown in FIG. Radio waves radiated from radiator 41 toward reflecting mirror 42 are reflected by reflecting mirror 42 to form a beam in the forward direction. At this time, if the focal positions of the radiator 41 and the reflecting mirror 42 match, ideally the parallel beams are formed as shown in FIG. 9, the beams are narrow, and the antenna gain is large. Conversely, when the focal positions of the radiator 41 and the reflector 42 are shifted, the beam becomes wider and the antenna gain becomes smaller.

A parabolic antenna that can be used in the wireless communication device according to the third embodiment includes a first radiator 41, a second radiator 51, and a reflector 42, as shown in FIG. That is, it has a configuration in which a second radiator 51 is added to a general parabolic antenna. In the figure, the second radiator 51 is arranged to be shifted from the focal position of the reflector 42 and the first radiator 41 is arranged to be the focal position of the reflector 42 . The first radiator 41 emits a UL signal, and the second radiator 51 emits an LL signal.

The first radiator 41 is located at the focal position of the reflector 42, has a high antenna gain, and forms a narrow beam (parallel beam). On the other hand, the second radiator 51 is deviated from the focal position of the reflector 42, so that the antenna gain is low and a wide beam is formed. Therefore, the beam from the first radiator 41 is used for transmitting the UL signal, and the beam from the second radiator 51 is used for transmitting the LL signal, thereby generating an LDM signal as shown in FIG. can be done. Thus, in the third embodiment, the UL beam width is narrowed and the LL beam width is widened by adjusting the arrangement of the first radiator 41 and the second radiator 51. .

In the third embodiment, it is difficult to electronically beam scan the UL signal as in the first embodiment, so the antenna itself must be mechanically rotated for beam scanning. However, on the other hand, it is possible to provide the LDM configuration at a very low cost compared to the first embodiment.

(Fourth embodiment)
A radio communication apparatus according to a fourth embodiment of the present invention will be described. Digital modulation schemes used in UL and LL include a synchronous detection scheme in which information is transmitted on absolute amplitude and absolute phase, and a differential detection scheme in which information is transmitted on relative amplitude and phase. When performing synchronous detection, it is necessary to grasp the absolute amplitude and the absolute phase on the receiving side. On the other hand, when the differential detection method is performed, it is assumed that adjacent time and frequency have coherence, and the difference is used, so there is no need to grasp the absolute amplitude and absolute phase.

Coherent detection often uses a pilot signal whose amplitude and phase are known. Specifically, the pilot signals are distributed over time and frequency within the band, and the receiving side interpolates the received pilot signals in the frequency and time directions to estimate the characteristics of the transmission path. do. Then, in demodulation processing, synchronous detection processing is performed based on the estimated channel characteristics.

In the first to third embodiments, the relationship between the amplitude and phase of UL and LL on the transmitting side is not maintained on the receiving side. Therefore, it is necessary to use a pilot signal for demodulating the UL and a pilot signal for demodulating the LL. Therefore, the UL pilot signal and the LL pilot signal are arranged in the transmission band so that they are orthogonal in time, frequency, or code.

FIG. 11 shows an example of pilot signal arrangement in the fourth embodiment. The horizontal axis of FIG. 11 represents the frequency direction. In the figure, UL pilot signals and LL pilot signals are arranged so as to be orthogonal in the frequency domain.

Next, the case where orthogonality is maintained in the code domain will be described. Assuming that the UL pilot signal is P _UL and the LL pilot signal is P _LL , even symbols transmit P _even =P _UL +P _LL , and odd symbols transmit P _odd =P _UL -P _LL . On the receiving side, when extracting the UL pilot signal, P _UL =0.5 (P _even +P _odd ) is calculated, and when extracting the LL pilot signal, P _LL =0.5 (P _even -P _odd ).

In this way, by arranging the pilot signals so that the UL and LL are orthogonal to each other, it is possible to demodulate even with the coherent detection method.
Furthermore, it is also possible to combine synchronous detection and differential detection in UL and LL. In this case, the pilot signal should be arranged only in the hierarchy of coherent detection.
The above description is suitable for multi-carrier systems such as OFDM signals, but even for single-carrier systems, preamble signals with known amplitudes and phases may be arranged in a temporally orthogonal relationship. .

Although the present invention has been described in detail based on the first to fourth embodiments, it is needless to say that the present invention is not limited to these embodiments and can be widely applied to applications other than those described above. For example, in the above explanation, two types of data are transmitted using two layers, the upper layer (UL) and the lower layer (LL). can be
The present invention can also be provided as, for example, a method or system for executing processing according to the present invention, a program for realizing such a method or system, or a storage medium for storing the program.

INDUSTRIAL APPLICABILITY The present invention is effective when transmitting a plurality of data of different types with the same frequency and time.

11: Upper layer modulation section 12: Lower layer modulation section 13: Upper IL control section 14: Lower IL control section 15: Upper layer amplitude/phase control section 16: Lower layer amplitude/phase control section 17: synthesizing unit, 18: RF conversion unit, 19: antenna unit,
21, 31: base station, 22 to 24, 32: terminal station,
41, 51: Radiator, 42: Reflector,
100: UL data processing unit, 101: LL data processing unit, 121U: UL error correction coding unit, 121L: LL error correction coding unit, 122U: UL carrier modulation unit, 122L: LL carrier modulation unit, 123U, 123L: Power adjustment unit 124: Combining unit 125: OFDM modulation unit 126: Transmission antenna 130: Reception antenna 131: OFDM demodulation unit 132: UL carrier demodulation unit 133: UL error correction decoding unit 134: Replica generator, 135: removal processor, 136: LL carrier demodulator, 137: LL error correction decoder

Claims (8)

In a wireless communication device that transmits a plurality of data by hierarchical division multiplexing,
an antenna that outputs a first beam for transmitting first data and a second beam for transmitting second data different in type from the first data in space at the same frequency and time;
a power ratio adjustment unit that adjusts the power ratio of the first beam and the second beam;
A beam width control unit that controls the widths of the first beam and the second beam,
the first data is data for a specific radio station among a plurality of radio stations with which the radio communication device can communicate;
The second data is data used for controlling transmission of the first data, has a transmission rate lower than that of the first data, and is timing synchronized with the plurality of radio stations including the specific radio station. contains information for taking
The beam width control unit narrows the width of the first beam and widens the width of the second beam,
The antenna outputs the narrowly controlled first beam in the direction of the specific radio station, and outputs the widely controlled second beam to a range including the plurality of radio stations. wireless communication device. The wireless communication device according to claim 1 ,
The power ratio adjustment unit is configured such that, in the transmission direction of the first beam and the range of the width of the first beam, the radiation power of the first beam is greater than the radiation power of the second beam, and a predetermined power difference A wireless communication device characterized by adjusting as above. The wireless communication device according to claim 1 ,
The power ratio adjustment unit is configured such that, in the range of the transmission direction of the first beam and the width of the first beam, the radiation power of the second beam is greater than the radiation power of the first beam, and a predetermined power difference A wireless communication device characterized by adjusting as above. The wireless communication device according to claim 1 ,
A wireless communication device, wherein the second data includes location information of the wireless communication device. The wireless communication device according to claim 1,
The wireless communication device, wherein the beam width control unit digitally controls the widths of the first beam and the second beam. The wireless communication device according to claim 1,
The wireless communication device, wherein the beam width controller controls the widths of the first beam and the second beam in an analog manner. The wireless communication device according to claim 1,
The antenna includes a reflector, a first radiator that radiates radio waves of the first data to the reflector to generate the first beam, and a radio wave of the second data that is radiated to the reflector. a second radiator for generating the second beam;
The beam width control unit controls the width of the first beam and the second beam by adjusting the position of the first radiator and the position of the second radiator with respect to the reflecting mirror. wireless communication device. The wireless communication device according to claim 1,
A pilot signal used for demodulating the first data and a pilot signal used for demodulating the second data are arranged in an orthogonal relationship in the time, frequency, or code domain and transmitted. wireless communication device.

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