JP2010011023A - Radio communication system, radio transmitter, radio receiver, and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system can reduce transmission power when a frequency signal is made into segments and transmitted from the radio transmitter to the radio receiver, and to provide a radio transmitter, a radio receiver and a radio communication method. <P>SOLUTION: The radio transmitter communicates with the radio receiver and includes: a division part which divides the frequency signal to be transmitted to the radio receiver into a plurality of segments; an arrangement part which arranges the segments divided by the division part on a frequency axis; a multiplication part which multiplies any frequency signal included in each segment arranged on the frequency axis by the arrangement part by a gain smaller than 1; and a transmitting part which transmits the signal multiplied by the gain smaller than 1 by the multiplication part to the radio receiver. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication system, a wireless transmission device, a wireless reception device, and a wireless communication method.

In the uplink of a cellular system, when a small terminal transmits data, a single carrier method is widely used from the viewpoint of power use efficiency.
For example, in a 3.9th generation public mobile communication system, an SC that blocks a data signal, performs time-frequency conversion by DFT (Discrete Fourier Transform), and places the obtained frequency signal at an arbitrary frequency. -A transmission system called a single carrier frequency division multiple access (FDMA) system is used.

  In such a transmission system based on a single carrier, dynamic spectrum control (DSC) is known as a transmission technique for controlling radio resources more flexibly (Non-patent Document 1).

A wireless transmission device (FIG. 9) and a wireless reception device (FIG. 10) when dynamic spectrum control (DSC) is applied will be described below. Here, blocks the single carrier data N _u points, allocated to the discrete frequencies of the N _d points. Note that N _u <N _d .

  FIG. 9 is a schematic block diagram showing a configuration of a conventionally known wireless transmission apparatus 1000. Radio transmitting apparatus 1000 includes coding section 1001, modulating section 1002, DFT section 1003, spectrum arranging section 1004, IDFT (Inverse Discrete Fourier Transform) section 1005, pilot generating section 1006, pilot inserting section 1007, CP ( A Cyclic Prefix (cyclic prefix) insertion unit 1008, a D / A (Digital to Analog) conversion unit 1009, a radio unit 1010, and a transmission antenna 1011 are provided.

In the wireless transmission apparatus 1000 of FIG. 9, the information bits are error correction encoded by the encoding unit 1001 and output to the modulation unit 1002. With respect to the code bits output from the code unit 1001, a modulation signal is generated from the code bits in the modulation unit 1002, and is output to the DFT unit 1003 as a data signal.
Next, the DFT unit 1003 converts the discrete frequency signal into _Nu point discrete frequency signals, and a part of the obtained discrete frequency signal is converted from the _Nd point to N by the spectrum arrangement unit 1004 according to the reception status in discrete frequency signal units. _u points are selected and assigned discrete frequency signals.

Next, the allocated frequency signal is converted into an _Nd point time signal by IDFT section 1005 and output to pilot insertion section 1007. On the other hand, pilot generation section 1006 generates a pilot signal for estimating the characteristics of the radio propagation path, is multiplexed with the data signal by pilot multiplexing section 1007, and CP insertion section 1008 generates a waveform behind a part of the data signal. It is added as a cyclic prefix (CP), converted from a digital signal to an analog signal by the D / A converter 1009, up-converted to a radio frequency by the radio unit 1010, and transmitted from the transmission antenna 1011 to the radio receiver.

  FIG. 10 is a schematic block diagram showing a configuration of a conventionally known wireless reception device 2000. Radio receiving apparatus 2000 includes receiving antenna 1021, radio section 1022, A / D (Analog to Digital) converter 1023, CP removal section 1024, pilot separation section 1025, propagation path estimation section 1026, and spectrum allocation information generation. Unit 1027, buffer 1028, propagation path characteristic extraction unit 1029, DFT unit 1030, spectrum extraction unit 1031, equalization unit 1032, IDFT unit 1033, demodulation unit 1034, and decoding unit 1035.

In radio receiving apparatus 2000 shown in FIG. 10, a received signal from radio transmitting apparatus 1000 is received by receiving antenna 1021, down-converted from a radio frequency to a baseband signal by radio section 1022, and output to A / D conversion section 1023. Is done.
Next, the analog signal is converted into a digital signal by the A / D conversion unit 1023 and output to the CP removal unit 1024. The received signal converted into the digital signal is removed from the cyclic prefix (CP) by the CP removing unit 1024 and separated into the received pilot signal and the received data signal by the pilot separating unit 1025.

In the received pilot signal, the channel gain estimation unit 1026 estimates the frequency gain of N _d points that are allocatable bands, and the spectrum allocation information generation unit 1027 selects _Nu points of discrete frequencies with good reception conditions. The spectrum allocation information is generated and fed back to the wireless transmission device 1000 (FIG. 9).
On the other hand, the generated spectrum allocation information is stored in the buffer 1028 because it is used for extracting frequency signals in the next transmission opportunity.

On the other hand, the propagation path characteristic estimated by the propagation path estimation unit 1026 is based on the spectrum allocation information from the buffer 1028 saved at the previous transmission opportunity, and the propagation path characteristic of the frequency used for transmission is extracted from the propagation path characteristic. Part 1029 is extracted.
The DFT unit 1030 is converted into a frequency signal by performing discrete Fourier transform of N _d points (DFT), the propagation path characteristic spectrum extraction unit 1031 from the spectrum allocation information stored in the extraction process as well as the buffer 1028 of N _{The u-} point received data signal is extracted.

At this stage, both the propagation path characteristic and the received data signal can be regarded as transmissions equivalent to the single carrier transmission method, so that the propagation path characteristic obtained from the propagation path characteristic extraction unit 1029 and the spectrum extraction unit 1031 are obtained. Using the received data signal, equalization section 1032 performs equalization processing to compensate for frequency signal distortion caused by the radio propagation path.
Equalized signal is converted to a time signal by performing the IDFT unit 1033 inverse discrete Fourier transform of _{N u} points (IDFT). Thereafter, the demodulator 1034 separates the modulated signal from the received signal in bit units, and the decoder 1035 performs error correction decoding processing to obtain decoded bits.

  As described above, in the dynamic spectrum control (DSC), the frequency selective diversity effect capable of selecting and transmitting the frequency having the good reception condition can be obtained by arranging the discrete frequency signal independently at the discrete frequency having the good reception condition. Good transmission characteristics can be obtained (Non-Patent Document 1).

However, in this method, zeros are arranged between discrete frequency signals by discontinuously arranging single carrier frequency signals on the frequency axis. This is an effective method considering that high peak power is generated at the output of the IDFT unit 1005 of the wireless transmission device 1000 shown in FIG. 9 and originally based on a single carrier signal for the purpose of suppressing the peak power. There wasn't.
In contrast, Non-Patent Document 2 describes a method in which the obtained discrete frequency signal is segmented into a plurality of continuous discrete frequency signals and arranged on the frequency axis in segment units.
S.Sampei and S.Ibi, “Flexible Spectrum Control and Receiver Performance Implication Technologies for B3G Wireless Systems” in Ec. Hideo Namba et al. “Examination of dynamic spectrum control considering PAPR”, IEICE General Conference 2008, B-5-51, March 2008

  However, even if the frequency signal is segmented, there is a problem that the peak power is higher than that of single carrier transmission, and the transmission power when transmitting a signal from the wireless transmission device to the wireless reception device is large.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wireless communication system that can reduce transmission power when a frequency signal is segmented and transmitted from the wireless transmission device to the wireless reception device. To provide a wireless transmission device, a wireless reception device, and a wireless communication method.

(1) The present invention has been made to solve the above problems, and a wireless communication system according to an aspect of the present invention is a wireless communication system including a wireless transmission device and a wireless reception device, wherein the wireless transmission An apparatus includes: a division unit that divides a frequency signal to be transmitted to the wireless reception device into a plurality of segments; an arrangement unit that arranges the segments divided by the division unit on a frequency axis; and the arrangement unit that is arranged on the frequency axis. A multiplication unit that multiplies any frequency signal included in each segment by a gain smaller than 1, and a transmission unit that transmits a signal obtained by multiplying the gain by a multiplication unit smaller than 1 to the radio reception apparatus. The radio reception apparatus includes: a reception unit that receives a signal transmitted from the transmission unit; and a signal that detects a frequency signal from the signal received by the reception unit using a gain multiplied by the multiplication unit. And a detection unit.

(2) In the wireless communication system according to the aspect of the present invention, the multiplication unit multiplies the frequency signals at both ends of each segment arranged by the arrangement unit on the frequency axis by a gain smaller than 1.

(3) In addition, the multiplication unit of the wireless communication system according to an aspect of the present invention multiplies the gain using a window function.

(4) In addition, in the wireless communication system according to one aspect of the present invention, when a plurality of segments arranged on the frequency axis by the arrangement unit are adjacent to each other, the multiplication unit includes any one of the plurality of segments. Multiply the frequency signal by a gain less than one.

(5) A wireless transmission device according to an aspect of the present invention is a wireless transmission device that communicates with a wireless reception device, and a dividing unit that divides a frequency signal to be transmitted to the wireless reception device into a plurality of segments, An arrangement unit that arranges the segments divided by the division unit on the frequency axis; and a multiplication unit that multiplies any frequency signal included in each segment arranged by the arrangement unit on the frequency axis by a gain smaller than 1. The multiplication unit includes a transmission unit that transmits a signal multiplied by a gain smaller than 1 to the wireless reception device.

(6) A wireless reception device according to an aspect of the present invention is a wireless reception device that communicates with a wireless transmission device, and is disposed on a frequency axis with a reception unit that receives a signal transmitted by the wireless transmission device. A signal detection unit configured to detect a frequency signal from a signal received by the reception unit using a gain smaller than 1 multiplied by any one of the frequency signals included in each segment by the wireless transmission device.

(7) A wireless communication method according to an aspect of the present invention is a wireless communication method using a wireless transmission device and a wireless reception device, and the wireless transmission device transmits a frequency signal to be transmitted to the wireless reception device. A division process for dividing into a plurality of segments, an arrangement process for arranging the segments divided in the division process on the frequency axis, and any frequency signal included in each segment arranged on the frequency axis in the arrangement process A multiplication process for multiplying a gain smaller than 1 and a transmission process for transmitting a signal multiplied by a gain smaller than 1 in the multiplication process to the radio reception apparatus, wherein the radio reception apparatus transmits in the transmission process. A reception process for receiving the received signal, and a signal detection process for detecting a frequency signal from the signal received in the reception process using the gain multiplied in the multiplication process.

  In the wireless communication system, the wireless transmission device, the wireless reception device, and the wireless communication method of the present invention, it is possible to reduce the transmission power when the frequency signal is segmented and transmitted from the wireless transmission device to the wireless reception device. Play.

In the following embodiments, the present invention is applied to an uplink (transmission of a signal from a mobile station apparatus to a base station apparatus) in a cellular system, and the number of original single carrier signals to be blocked is _Nu . Although the case where the number of assignable frequency points is N _d will be described, the present invention may be applied to the downlink (transmission of signals from the base station apparatus to the mobile station apparatus).
In addition, a case where frequency domain equalization based on a minimum mean square error (MMSE) standard is used as the equalization process will be described. In the radio reception apparatus, other equalization techniques other than the least square error criterion may be used.
In the following embodiments, a segment is a name of each block when the obtained _Nd- point frequency signal is divided into a plurality of blocks (groups). The segment size represents the number of points of the frequency signal included in each block.

[First Embodiment]
First, a first embodiment of the present invention will be described. The wireless communication system according to the first embodiment of the present invention includes a wireless transmission device and a wireless reception device.
In addition to this embodiment, in all embodiments, as an example, the wireless transmission device is provided in a small portable terminal of a wireless communication system, and the wireless reception device is provided in a base station device or a relay device.

  FIG. 1 is a schematic block diagram showing a configuration of a wireless transmission device 100 according to the first embodiment of the present invention. The wireless transmission device 100 includes a coding unit 1, a modulation unit 2, a DFT (Discrete Fourier Transform) unit 3, a spectrum arrangement unit 4, an amplitude limiting unit 5, an IDFT (Inverse Discrete Fourier Transform) unit. 6, a pilot generation unit 7, a pilot insertion unit 8, a CP (Cyclic Prefix) insertion unit 9, a D / A (Digital to Analog) conversion unit 10, a radio unit 11, and a transmission antenna 12 ing.

In the wireless transmission device 100 of FIG. 1, the information bits are error correction encoded by the encoder 1 and output to the modulator 2. Then, a modulation signal such as 16 QAM (16 Quadrature Amplitude Modulation) is generated from the code bit in the modulation unit 2 and is output to the DFT unit 3 as a data signal.
Then, the DFT unit 3, is converted into a discrete frequency signal N _u points, some of the resulting discrete frequency signals, from the N _d points depending on the reception conditions at discrete frequency signal units by spectral placement section 4 _Nu points are selected and assigned discrete frequency signals.

In the amplitude limiting unit 5, the frequency signal output from the DFT unit 3 is segmented by allocating the frequency signal on the frequency axis based on the spectrum allocation information, and a gain for limiting the amplitude of the frequency signal at both ends of each segment ( For example, 0.5) and outputs the result to the IDFT unit 6.
If there is one or two frequency signals included in the segment, there is no concept of both ends of the segment. In this case, do not multiply the frequency signal included in the segment by a gain. Also good.

Then, the frequency signal output from the amplitude limiting unit 5 is converted to a time signal of N _d points by IDFT unit 6, is output to the pilot insertion unit 8. On the other hand, the pilot generation unit 7 generates a pilot signal for estimating the characteristics of the radio propagation path, and the pilot insertion unit 8 multiplexes it with the data signal. The multiplexing method may be either time multiplexing or frequency multiplexing. The output of the pilot insertion unit 8 is added to the front of the data signal as a cyclic prefix (CP) by the CP insertion unit 9 as a waveform behind a part of the data signal, and then the D / A conversion unit 10 The digital signal is converted into an analog signal, is up-converted to a radio frequency by the radio unit 11, and is transmitted from the transmission antenna 12 to the radio reception device 200.

  FIG. 2 is a schematic block diagram showing the configuration of the wireless reception device 200 according to the first embodiment of the present invention. The radio reception apparatus 200 includes a reception antenna 20, a radio unit 21, an A / D (Analog to Digital) conversion unit 22, a CP removal unit 23, a pilot separation unit 24, a propagation path estimation unit 25, and spectrum allocation information generation. Unit 26, buffer 27, equivalent channel calculation unit 28, channel characteristic extraction unit 29, DFT unit 30, spectrum extraction unit 31, equalization unit 32, IDFT unit 33, demodulation unit 34, and decoding unit 35.

In the radio reception device 200 shown in FIG. 2, a reception signal from the radio transmission device 100 (FIG. 1) is received by the reception antenna 20, down-converted from a radio frequency to a baseband signal by the radio unit 21, and A / D The data is output to the conversion unit 22.
Next, the signal output from the radio unit 21 is converted from an analog signal to a digital signal by the A / D conversion unit 22 and output to the CP removal unit 23.
The received signal converted into the digital signal by the A / D conversion unit 22 is removed from the cyclic prefix (CP) by the CP removal unit 23 and separated into the reception pilot signal and the reception data signal by the pilot separation unit 24.

Received pilot signal is estimated frequency gain of the channel of the N _d points fraction is allocated band by a channel estimation unit 25, select only good discrete frequency N _u points reception conditions by spectrum allocation information generation unit 26 Thus, spectrum allocation information is generated and fed back to the wireless transmission device 100 (FIG. 1) via a wireless unit and an antenna (not shown).
On the other hand, the generated spectrum allocation information is stored in the buffer 27 in order to be used for extraction of frequency signals at the next transmission opportunity.

The equivalent propagation path calculation unit 28 multiplies the frequency response at both ends of the corresponding segment by the gain for suppressing the peak power multiplied by the amplitude limiting unit 5 in the wireless transmission device 100.
For example, when N _d = 12 and N _u = 8, the propagation path characteristic 推定 estimated by the propagation path estimation unit 25 is expressed by the following equation (1).

Here, Ξ (k) is the complex channel gain of the kth frequency in the assignable frequency band of _Nd points. Next, when the segment size is 4, and the transmission signals are arranged at the 2nd to 5th discrete frequencies and the 8th to 11th discrete frequencies, a gain of 0.5 is multiplied at both ends of the segment for the purpose of peak suppression. The equivalent channel characteristic Ξ _eq calculated by the equivalent channel calculation unit 28 is expressed by the following equation (2).

  A propagation path characteristic Ξ ′ used for equalization processing extracted from the equivalent propagation path obtained from the equivalent propagation path obtained by the equation (2) is finally given by the following equation (3). .

The propagation path characteristic obtained by Expression (3) is used for equalization processing in the equalization unit 32. Here, a matrix W (also referred to as a tap matrix) to be subjected to equalization processing to be multiplied with respect to frequency signals extracted from N _d points to N _u points with the same parameters is given by the following equation (4). .

In equation (4), σ ² is the noise variance. Further, I is a unit matrix of N _u × N _u in which only the diagonal component is 1 and the remaining elements are 0. X ^H is an adjoint matrix obtained by taking a complex conjugate of a matrix or a vector x and transposing (hermitian transposition). At this time, the equalization processing in the equalization unit 32 is expressed by the following equation (5).

However, in Expression (5), R ′ is a substantial received signal obtained by extracting _Nu points from the received signal of N _d points, and is represented by the following Expression (6).

However, x ^T is an operator which transposed vector x and the matrix x. Thus, since processing similar to that of the conventional dynamic spectrum control (DSC) can be performed while reducing the peak, the peak power can be reduced while obtaining the highest possible frequency selection diversity effect.
In this embodiment, the gain for limiting the amplitude is set to 0.5. However, if the gain is set to a value smaller than 1, other values may be used. In order to halve the energy of the frequency signals at both ends, the gain should be 1 / √2.

  On the other hand, the propagation path characteristic estimated by the propagation path estimation unit 25 is extracted from the propagation path gain of the frequency used for transmission based on the spectrum allocation information from the buffer 27 stored at the previous transmission opportunity. Extracted in part 29.

N _D point discrete Fourier transform (DFT) is performed by the DFT unit 30 to be converted into a frequency signal, and the spectrum extraction unit 31 uses the spectrum allocation information stored in the buffer 27 in the same manner as the channel characteristic extraction process. _{The u-} point received data signal is extracted.
At this stage, both the propagation path characteristics and the received data signal can be regarded as transmissions equivalent to the single carrier transmission system, so the propagation path characteristics obtained from the propagation path characteristics extraction section 29 and the spectrum extraction section 31 Using the received data signal, and using equation (5), the equalizer 32 performs equalization processing to compensate for the distortion of the frequency signal due to the radio propagation path.

Equalized signal by the equivalent unit 32 is converted to a time signal from the frequency signal by performing the IDFT unit 33 inverse discrete Fourier transform of N _u points (IDFT). Thereafter, the demodulating unit 34 separates the modulated signal into a received signal in bit units, and the decoding unit 35 performs error correction decoding processing to obtain decoded bits.

FIG. 3A and FIG. 3B are diagrams for explaining processing of the amplitude limiting unit 5 of the wireless transmission device 100 according to the first embodiment of the present invention. In FIG. 3A and FIG. 3B, the horizontal axis is frequency.
FIG. 3A shows an example of a signal input to the amplitude limiting unit 5 of the wireless transmission device 100, and four segments c01 to c04 are arranged on the frequency axis. The segment c01 includes frequency signals s001 to s004, the segment c02 includes frequency signals s005 to s008, the segment c03 includes frequency signals s009 to s012, and the segment c04 includes a frequency signal. Signals s013 to s016 are included.

  FIG. 3B shows an example of a signal output from the amplitude limiting unit 5 of the wireless transmission device 100, and shows a case where four segments c11 to c14 are arranged on the frequency axis. . The segment c11 includes frequency signals s101 to s104, the segment c12 includes frequency signals s105 to s108, the segment c13 includes frequency signals s109 to s112, and the segment c14 includes a frequency signal. Signals s113 to s116 are included.

The frequency signals s101 and s104 at both ends of the segment c11 are smaller in amplitude than the frequency signals s102 and s103 other than both ends of the segment c11.
In addition, the frequency signals s105 and s108 at both ends of the segment c12 have a smaller amplitude than the frequency signals s106 and s107 other than both ends of the segment c12.
Further, the frequency signals s109 and s113 at both ends of the segment c13 are smaller in amplitude than the frequency signals s111 and s112 other than both ends of the segment c13.
Further, the frequency signals s113 and s116 at both ends of the segment c14 have a smaller amplitude than the frequency signals s114 and s115 other than both ends of the segment c14.

The reason why the peak power is increased by segmenting the frequency signal as shown in FIG. 3A is that 0 is arranged between the segments when the frequency signal is arranged on the frequency axis. In this case, the frequency signal becomes discontinuous.
In the present embodiment, in order to solve this problem, as shown in FIG. 3B, among the plurality of frequency signals included in each segment, the amplitudes of the frequency signals at both ends are limited to be low, and the radio receiving device 200 On the side, the gain limitation of the frequency signal is regarded as attenuation by the propagation path and equalized.

FIG. 4 is a sequence diagram showing processing of the wireless communication system according to the first embodiment of the present invention. First, the spectrum arrangement unit 4 (also referred to as a dividing unit) of the wireless transmission device 100 divides a frequency signal to be transmitted to the wireless reception device 200 into a plurality of segments c01 to c04 (step S11).
And the spectrum arrangement | positioning part 4 (it is also called arrangement | positioning part) of the radio | wireless transmitter 100 arrange | positions the segments c01-c04 divided | segmented by step S11 on a frequency axis, as shown to Fig.3 (a) (step S12).

  Then, the amplitude limiting unit 5 (also referred to as a multiplication unit) of the wireless transmission device 100 performs any frequency signal included in each of the segments c01 to c04 arranged on the frequency axis by the spectrum arrangement unit 4 in step S12. Multiply by a gain less than one. Specifically, in the present embodiment, the amplitude limiting unit 5 includes frequency signals (for example, frequency signals s001 and s001) at both ends of each segment (for example, segment c01) arranged on the frequency axis by the spectrum arranging unit 4 in step S12. s004) is multiplied by a gain smaller than 1 (step S13). Thereby, the amplitudes of the frequency signals s001 to s016 in FIG. 3A become the amplitudes of the frequency signals s101 to s116 in FIG.

The radio unit 11 (also referred to as a transmission unit) of the radio transmission apparatus 100 is a signal obtained by multiplying the amplitude limiting unit 5 by a gain smaller than 1 in step S13, and includes an IDFT unit 6, a pilot insertion unit 8, and a CP insertion unit. 9. The signal that has passed through the D / A converter 10 is transmitted to the wireless reception device 200 via the transmission antenna 12 (step S14).
Then, the radio unit 21 (also referred to as a reception unit) of the radio reception device 200 receives the signal transmitted by the radio unit 11 of the radio transmission device 100 via the transmission antenna 12 in step S14 (step S15).

And the equalization part 32 (it is also called a signal detection part) of the radio | wireless receiving apparatus 200 uses the gain which the amplitude limiting part 5 (FIG. 1) of the radio | wireless transmission apparatus 100 multiplied, and uses the signal shown in FIG.3 (b). The signal shown in FIG. 3A is received by the radio unit 21 in step S15. The A / D conversion unit 22, the CP removal unit 23, the pilot separation unit 24, the DFT unit 30, the spectrum A frequency signal is detected from the signal that has passed through the extraction unit 31 (step S16).
Note that the gain used by the amplitude limiting unit 5 of the wireless transmission device 100 in step S13 and the gain used by the equalization unit 32 of the wireless reception device 200 in step S16 are the same as those received by the wireless transmission device 100 before starting communication. It is preset in the apparatus 200.

By using the wireless communication system according to the first embodiment described above, it is possible to reduce the transmission power when the frequency signal is segmented and transmitted from the wireless transmission device 100 to the wireless reception device 200.
In the wireless communication system according to the first embodiment, since peak power can be reduced without reducing the segment size, high power utilization efficiency is achieved while realizing a high selection diversity effect and flexible frequency allocation. be able to.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The communication system according to the second embodiment of the present invention includes a wireless transmission device and a wireless reception device. The radio transmission apparatus and radio reception apparatus according to the second embodiment have the same configurations and functions as those of the radio transmission apparatus 100 (FIG. 1) and radio reception apparatus 200 (FIG. 2) according to the first embodiment. However, the mode of gain for peak power suppression used in the amplitude control unit 5 and the propagation path characteristic extraction unit 29 is different. Therefore, the description of the same part of a structure and a function is abbreviate | omitted.

FIGS. 5A and 5B are diagrams for explaining processing of the amplitude limiting unit 5 of the wireless transmission device 100 according to the second embodiment of the present invention. In FIG. 5A and FIG. 5B, the horizontal axis is frequency.
FIG. 5A illustrates an example of a signal input to the amplitude limiting unit 5 of the wireless transmission device 100, and four segments c01 to c04 are arranged on the frequency axis. The segment c01 includes frequency signals s001 to s004, the segment c02 includes frequency signals s005 to s008, the segment c03 includes frequency signals s009 to s012, and the segment c04 includes a frequency signal. Signals s013 to s016 are included.

  FIG. 5B shows an example of a signal output from the amplitude limiting unit 5 of the wireless transmission device 100, and four segments c21 to c24 are arranged on the frequency axis. The segment c21 includes frequency signals s201 to s204, the segment c22 includes frequency signals s205 to s208, the segment c23 includes frequency signals s209 to s212, and the segment c24 includes a frequency signal. Signals s213 to s216 are included.

The frequency signals s201 and s204 at both ends of the segment c21 are smaller in amplitude than the frequency signals s202 and s203 other than both ends of the segment c21.
Further, the frequency signals s205 and s208 at both ends of the segment c22 are smaller in amplitude than the frequency signals s206 and s207 other than both ends of the segment c22.
In addition, the frequency signals s209 and s213 at both ends of the segment c23 have a smaller amplitude than the frequency signals s211 and s212 other than both ends of the segment c23.
Further, the frequency signals s213 and s216 at both ends of the segment c24 have a smaller amplitude than the frequency signals s214 and s215 other than both ends of the segment c24.

If the signal shown in FIG. 5A remains as it is, the transmission power of the signal transmitted from the wireless transmission device 100 to the wireless reception device 200 increases. Therefore, in the present embodiment, as shown in FIG. 5B, a conventionally known window function is multiplied by a frequency signal included in each segment. As the window function, a Hamming window, Hanning window, Blackman window, or the like can be used.
The window functions of the Hamming window, Hanning window, and Blackman window are expressed by the following equations (7), (8), and (9), respectively.

In the formula (7) to Formula (9), [pi is pi, N _s is the number of discrete frequency signals contained in the segment. In Equations (7) to (9), k represents a discrete frequency index of an allocatable band. When calculating the gain, k = 0 is set for each segment for the sake of convenience. Calculate as
For example, when considering the 3rd to 10th segments, k = 3 is actually replaced with k = 0 to k = 7, and the values of Equations (7) to (9) are calculated. Calculate the window gain.

The window function is set in advance between the wireless transmission device 100 and the wireless reception device 200 before the start of communication. On the wireless reception device 200 side, the window gain can be calculated by the same calculation method from the spectrum allocation information. Therefore, as shown in the first embodiment, the signal can be detected by the wireless reception device 200 by equivalently treating it as the gain of the propagation path.
Here, a description will be given of a case where the window function is applied by setting the window start point to the lowest frequency component in the segment k = 0, but when the segment size is smaller than a predetermined value, the discrete frequency signal having the lowest frequency For example, k = 0 or k = 2 may be used instead of k = 0, and the frequency may be such that 0 is arranged at the point where k = 0 equivalently. That is, a frequency wider than each segment size may be measured, and the section may be multiplied by the window.

FIG. 6 is a sequence diagram showing processing of the wireless communication system according to the second embodiment of the present invention. First, the spectrum arrangement unit 4 (also referred to as a dividing unit) of the wireless transmission device 100 divides a frequency signal to be transmitted to the wireless reception device 200 into a plurality of segments c01 to c04 (step S21).
And the spectrum arrangement | positioning part 4 (it also calls an arrangement | positioning part) of the radio | wireless transmitter 100 arrange | positions the segments c01-c04 divided | segmented by step S21 on a frequency axis, as shown to Fig.5 (a) (step S22).

  Then, the amplitude limiting unit 5 (also referred to as a multiplication unit) of the wireless transmission device 100 performs any frequency signal included in each of the segments c01 to c04 arranged on the frequency axis by the spectrum arrangement unit 4 in step S22. Multiply the gain less than 1 using the window function. Specifically, in the present embodiment, the amplitude limiting unit 5 includes frequency signals (for example, frequency signals s001 and s001) at both ends of each segment (for example, segment c01) arranged on the frequency axis by the spectrum arranging unit 4 in step S22. s004) is multiplied by a gain smaller than 1 using a window function (step S23). Thereby, the amplitudes of the frequency signals s001 to s016 in FIG. 5A become the amplitudes of the frequency signals s201 to s216 in FIG. 5B.

The radio unit 11 (also referred to as a transmission unit) of the radio transmission apparatus 100 is a signal obtained by multiplying the amplitude limiting unit 5 by a gain smaller than 1 using a window function in step S23, and includes an IDFT unit 6 and a pilot insertion unit. 8, the signal that has passed through the CP insertion unit 9, the D / A conversion unit 10, and the radio unit 11 is transmitted to the radio reception device 200 via the transmission antenna 12 (step S24).
Then, the radio unit 21 (also referred to as a reception unit) of the radio reception device 200 receives the signal transmitted by the radio unit 11 of the radio transmission device 100 via the transmission antenna 12 in step S24 (step S25).

Then, the equalization unit 32 (also referred to as a signal detection unit) of the wireless reception device 200 uses the gain multiplied by the amplitude limiting unit 5 (FIG. 1) of the wireless transmission device 100 using the window function, and uses FIG. ) Is converted into the signal shown in FIG. 5A, which is the signal received by the wireless unit 21 in step S25, and is the A / D conversion unit 22, the CP removal unit 23, the pilot separation unit 24, A frequency signal is detected from the signal that has passed through the DFT unit 30 and the spectrum extraction unit 31 (step S26).
Note that the window function and gain used by the amplitude limiting unit 5 of the wireless transmission device 100 in step S23 and the window function and gain used by the equalization unit 32 of the wireless reception device 200 in step S26 are wirelessly transmitted before starting communication. The transmission apparatus 100 and the wireless reception apparatus 200 are preset.

By using the wireless communication system according to the second embodiment described above, it is possible to reduce the transmission power when the frequency signal is segmented and transmitted from the wireless transmission device 100 to the wireless reception device 200.
In the wireless communication system according to the second embodiment, since peak power can be reduced without reducing the segment size, high power utilization efficiency is achieved while realizing a high selection diversity effect and flexible frequency allocation. be able to.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. A communication system according to the third embodiment of the present invention includes a wireless transmission device and a wireless reception device. The wireless transmission device and the wireless reception device according to the third embodiment have the same configurations and functions as those of the wireless transmission device 100 (FIG. 1) and the wireless reception device 200 (FIG. 2) according to the first embodiment. However, the mode of amplitude control by the amplitude control unit 5 is different. Therefore, the description of the same part of a structure and a function is abbreviate | omitted.

FIGS. 7A and 7B are diagrams for explaining processing of the amplitude limiting unit 5 of the wireless transmission device 100 according to the third embodiment of the present invention. In FIG. 7A and FIG. 7B, the horizontal axis is frequency.
FIG. 7A shows an example of a signal input to the amplitude limiting unit 5 of the wireless transmission device 100 according to the third embodiment, and three segments c01, c02, and c05 are arranged on the frequency axis. Yes.

Since the frequency signal s012 and the frequency signal s013 are adjacent on the frequency axis, the frequency signals s009 to s012 and the frequency signals s013 to s016 constitute one segment c05.
The segment c01 includes frequency signals s001 to s004, the segment c02 includes frequency signals s005 to s008, and the segment c05 includes frequency signals s009 to s016.

FIG. 7B shows an example of a signal output from the amplitude limiting unit 5 of the wireless transmission device 100 according to the third embodiment, and three segments c31 to c33 are arranged on the frequency axis. Yes.
Since the frequency signal s312 and the frequency signal s313 are adjacent to each other on the frequency axis, the frequency signals s309 to s312 and the frequency signals s313 to s316 form one segment c33.
The segment c31 includes frequency signals s301 to s304, the segment c32 includes frequency signals s305 to s308, and the segment c33 includes frequency signals s309 to s316.

The frequency signals s301 and s304 at both ends of the segment c31 are smaller in amplitude than the frequency signals s302 and s303 other than both ends of the segment c31.
Further, the frequency signals s305 and s308 at both ends of the segment c32 have a smaller amplitude than the frequency signals s306 and s307 other than both ends of the segment c32.
Further, the frequency signals s309 and s316 at both ends of the segment c33 are smaller in amplitude than the frequency signals s310, s311, s312, s313, s314, and s315 other than the ends of the segment c33.

  In FIG. 7 (a), four continuous frequency signals are segmented as a unit, and two segments (a segment including frequency signals s009 to s012 and a frequency signal s013 are divided by a stochastic factor such as propagation path fluctuation). As a result of the adjacent segments including s016, eight consecutive discrete frequency signals s009 to s016 are equivalently measured as being segmented.

In this case, there is no point in multiplying both ends of the segment by the gain as in the first or second embodiment, or by multiplying the window in segment units, and only the gain of the propagation path is lowered. .
Therefore, in this embodiment, as shown in FIG. 7B, when adjacent segments exist, the amplitude is limited only to the frequency signal adjacent to the frequency where 0 is arranged.
Also in the second embodiment, adjacent continuous frequency signals may be regarded as segments and multiplied by a window function. Thereby, the peak of transmission power can be effectively suppressed.

In this embodiment, even if there are one or two frequency signals to be segmented, if three or more frequency signals are included in adjacent segments, the adjacent segments are integrated and integrated. By multiplying the amplitude of the frequency signal at both ends of the segment by a gain smaller than 1 by the amplitude limiter 5, the transmission power of the signal transmitted from the wireless transmission device 100 to the wireless reception device 200 can be reduced.
In this case, the amplitude limiting unit 5 of the wireless transmission device 100 determines which segment is adjacent from the spectrum allocation information, and multiplies the amplitude of the frequency signal at both ends of the adjacent segment by a gain smaller than 1.

FIG. 8 is a sequence diagram showing processing of the wireless communication system according to the third embodiment of the present invention. First, the spectrum arrangement unit 4 (also referred to as a dividing unit) of the wireless transmission device 100 divides the frequency signal transmitted to the wireless reception device 200 into a plurality of segments c01, c02, and c05 (step S31). Here, since the segment including the frequency signals s009 to s012 and the segment including the frequency signals s013 to s016 are adjacent to each other, the spectrum arrangement unit 4 sets the two segments as a segment c05.
Then, the spectrum arrangement unit 4 (also referred to as arrangement unit) of the wireless transmission device 100 arranges the segments c01, c02, and c05 divided in step S31 on the frequency axis as shown in FIG. 7A (step S32). ).

  Then, the amplitude limiting unit 5 (also referred to as a multiplication unit) of the wireless transmission device 100 performs any frequency signal included in each of the segments c01 and c02 arranged on the frequency axis by the spectrum arrangement unit 4 in step S32. Multiply by a gain less than one. Further, the amplitude limiting unit 5 of the wireless transmission device 100 multiplies any frequency signal included in each segment c05 arranged on the frequency axis by the spectrum arranging unit 4 in step S32 by a gain smaller than 1.

Specifically, in the present embodiment, the amplitude limiting unit 5 includes frequency signals (for example, frequency signals s001 and s001) at both ends of each segment (for example, the segment c01) arranged on the frequency axis by the spectrum arranging unit 4 in step S32. s004) is multiplied by a gain less than 1.
Further, the amplitude limiting unit 5 is configured such that in step S32, the spectrum includes a plurality of segments (segments including the frequency signals s009 to s012 and segments including the frequency signals s013 to s016) adjacent to each other in the position unit 4 on the frequency axis. Is multiplied by a gain smaller than 1 for the frequency signals (for example, frequency signals s009 and s016) at both ends of the segment composed of the plurality of segments (here, segment c05) (step S33). As a result, the amplitudes of the frequency signals s001 to s016 in FIG. 7A become the amplitudes of the frequency signals s301 to s316 in FIG. 7B.

The radio unit 11 (also referred to as a transmission unit) of the radio transmission device 100 is a signal obtained by multiplying the amplitude limiting unit 5 by a gain smaller than 1 in step S33, and includes an IDFT unit 6, a pilot insertion unit 8, and a CP insertion unit. 9. The signal that has passed through the D / A converter 10 is transmitted to the wireless reception device 200 via the transmission antenna 12 (step S34).
Then, the radio unit 21 (also referred to as a reception unit) of the radio reception device 200 receives the signal transmitted by the radio unit 11 of the radio transmission device 100 via the transmission antenna 12 in step S34 (step S35).

And the equalization part 32 (it is also called a signal detection part) of the radio | wireless receiver 200 uses the gain which the amplitude limiting part 5 (FIG. 1) of the radio | wireless transmitter 100 multiplied, and uses the signal shown in FIG.7 (b). By converting into the signal shown in FIG. 7A, the signal received by the radio unit 21 in step S35, the A / D conversion unit 22, the CP removal unit 23, the pilot separation unit 24, the DFT unit 30, the spectrum A frequency signal is detected from the signal that has passed through the extraction unit 31 (step S36).
Note that the gain used by the amplitude limiting unit 5 of the wireless transmission device 100 in step S33 and the gain used by the equalization unit 32 of the wireless reception device 200 in step S36 are the same as those received by the wireless transmission device 100 before starting communication. It is preset in the apparatus 200.

By using the wireless communication system according to the third embodiment described above, it is possible to reduce the transmission power when the frequency signal is segmented and transmitted from the wireless transmission device 100 to the wireless reception device 200.
In the wireless communication system according to the third embodiment, since peak power can be reduced without reducing the segment size, high power utilization efficiency is achieved while realizing a high selection diversity effect and flexible frequency allocation. be able to.

  In the embodiment described above, a program for realizing the function of each unit of the wireless transmission device 100 (FIG. 1) and each unit of the wireless reception device 200 (FIG. 2) is recorded on a computer-readable recording medium. The wireless transmitter 100 and the wireless receiver 200 may be controlled by causing a computer system to read and execute a program recorded in the recording medium. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, it is also assumed that a server that holds a program for a certain time, such as a volatile memory inside a computer system that serves as a server or client. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design and the like within the scope of the present invention are also within the scope of the claims. include.

1 is a schematic block diagram illustrating a configuration of a wireless transmission device 100 according to a first embodiment of the present invention. It is a schematic block diagram which shows the structure of the radio | wireless receiver 200 by the 1st Embodiment of this invention. It is a figure explaining the process of the amplitude limitation part 5 of the radio | wireless transmitter 100 by the 1st Embodiment of this invention. It is a sequence diagram which shows the process of the radio | wireless communications system by the 1st Embodiment of this invention. It is a figure explaining the process of the amplitude limitation part 5 of the radio | wireless transmitter 100 by the 2nd Embodiment of this invention. It is a sequence diagram which shows the process of the radio | wireless communications system by the 2nd Embodiment of this invention. It is a figure explaining the process of the amplitude limitation part 5 of the radio | wireless transmitter 100 by the 3rd Embodiment of this invention. It is a sequence diagram which shows the process of the radio | wireless communications system by the 3rd Embodiment of this invention. It is a schematic block diagram which shows the structure of the wireless transmission apparatus 1000 known conventionally. It is a schematic block diagram which shows the structure of the wireless receiver 2000 conventionally known.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Code | symbol part, 2 ... Modulation part, 3 ... DFT part, 4 ... Spectrum arrangement | positioning part, 5 ... Amplitude limiting part, 6 ... IDFT part, 7 ... Pilot production | generation 8 is a pilot insertion part, 9 is a CP insertion part, 10 is a D / A conversion part, 11 is a radio part, 12 is a transmission antenna, 20 is a reception antenna, ... Radio unit, 22 ... A / D conversion unit, 23 ... CP removal unit, 24 ... Pilot separation unit, 25 ... Propagation path estimation unit, 26 ... Spectrum allocation information generation unit , 27 ... buffer, 28 ... equivalent channel calculation unit, 29 ... channel characteristic extraction unit, 30 ... DFT unit, 31 ... spectrum extraction unit, 32 ... equalization unit, 33... IDFT section, 34... Demodulation section, 35... Decoding section, 100. Radio receiving device

Claims (7)

A wireless communication system comprising a wireless transmission device and a wireless reception device,
The wireless transmission device
A dividing unit for dividing a frequency signal to be transmitted to the wireless reception device into a plurality of segments;
An arrangement unit that arranges the segment divided by the division unit on the frequency axis;
A multiplier that multiplies any frequency signal included in each segment arranged on the frequency axis by a gain smaller than 1;
A transmission unit that transmits a signal obtained by multiplying the gain by a gain smaller than 1 to the wireless reception device;
The wireless receiver is
A receiver for receiving the signal transmitted by the transmitter;
A radio communication system, comprising: a signal detection unit that detects a frequency signal from a signal received by the reception unit using a gain multiplied by the multiplication unit.   The wireless communication system according to claim 1, wherein the multiplication unit multiplies the frequency signals at both ends of each segment arranged on the frequency axis by the arrangement unit by a gain smaller than one.   The wireless communication system according to claim 1, wherein the multiplication unit multiplies the gain using a window function.   The multiplication unit multiplies any frequency signal included in the plurality of segments by a gain smaller than 1 when a plurality of segments arranged on the frequency axis by the arrangement unit are adjacent to each other. The wireless communication system according to claim 1. A wireless transmission device that communicates with a wireless reception device,
A dividing unit for dividing a frequency signal to be transmitted to the wireless reception device into a plurality of segments;
An arrangement unit that arranges the segment divided by the division unit on the frequency axis;
A multiplier that multiplies any frequency signal included in each segment arranged on the frequency axis by a gain smaller than 1;
A transmission unit that transmits a signal obtained by multiplying the gain by a gain smaller than 1 to the wireless reception device;
A wireless transmission device comprising: A wireless receiver that communicates with a wireless transmitter,
A receiver for receiving a signal transmitted by the wireless transmitter;
A signal detection unit for detecting a frequency signal from a signal received by the reception unit using a gain smaller than 1 multiplied by any one of the frequency signals included in each segment arranged on the frequency axis; ,
A radio receiving apparatus comprising: A wireless communication method using a wireless transmission device and a wireless reception device,
The wireless transmission device
A division process of dividing a frequency signal to be transmitted to the wireless reception device into a plurality of segments;
An arrangement process of arranging the segments divided in the division process on the frequency axis;
A multiplication step of multiplying any frequency signal included in each segment arranged on the frequency axis in the arrangement step by a gain smaller than 1,
A transmission step of transmitting a signal multiplied by a gain smaller than 1 in the multiplication step to the wireless reception device;
The wireless receiver is
A receiving process for receiving the signal transmitted in the transmitting process;
And a signal detection step of detecting a frequency signal from the signal received in the reception step using the gain multiplied in the multiplication step.

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