WO2012091013A1 - 受信装置および受信方法、並びにコンピュータプログラム - Google Patents
受信装置および受信方法、並びにコンピュータプログラム Download PDFInfo
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- WO2012091013A1 WO2012091013A1 PCT/JP2011/080213 JP2011080213W WO2012091013A1 WO 2012091013 A1 WO2012091013 A1 WO 2012091013A1 JP 2011080213 W JP2011080213 W JP 2011080213W WO 2012091013 A1 WO2012091013 A1 WO 2012091013A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
- H04L27/265—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
- G06F17/141—Discrete Fourier transforms
- G06F17/142—Fast Fourier transforms, e.g. using a Cooley-Tukey type algorithm
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
- H04L1/0036—Systems modifying transmission characteristics according to link quality, e.g. power backoff arrangements specific to the receiver
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0212—Channel estimation of impulse response
Definitions
- the present invention is an application based on Japanese Patent Application No. 2010-290031 filed on Dec. 27, 2010, and claims to receive the benefit of priority.
- the disclosure of the above application is hereby incorporated by reference in its entirety.
- the present invention relates to a receiving apparatus, a receiving method, and a computer program.
- Orthogonal Frequency Division Multiplexing is a wireless access method with high frequency utilization efficiency. Frequency Division Multiplexing is used.
- FIG. 11 is an overall configuration diagram of a communication system using a conventional OFDM system.
- a CPU central processing unit
- the encoding unit 111 performs CRC (cyclic) on the input information bits. redundancy check) and add convolutional coding.
- the modulation unit 112 modulates the input code data.
- the OFDM signal generation unit 113 maps the modulated data on the frequency axis, converts the data on the frequency axis to data on the time axis by digital Fourier inverse transform, and converts the converted data to D / A (Digital Analog ) Output to the conversion unit 114.
- the D / A converter 114 converts the converted data output from the OFDM signal generator 113 from a digital signal to an analog signal. Then, the modulated data converted into the analog signal is transmitted through the plurality of antennas 115.
- the receiving side is the user terminal 121.
- the user terminal 121 receives data transmitted from the antenna 115 of the base station 101 via the plurality of antennas 131. However, it should be noted that the data received by the antenna 131 is affected by noise when propagating through space after being output from the antenna 115.
- Data received by the antenna 131 is input to an A / D (Analog / Digital) converter 132.
- the A / D converter 132 converts the input data from an analog signal to a digital signal.
- the A / D conversion unit 132 outputs the converted digital signal to the OFDM signal demodulation unit 133.
- the OFDM signal demodulator 133 converts the digital signal on the time axis output from the A / D converter 132 into data on the frequency axis by digital Fourier transform, and maps it on the IQ plane.
- the demodulation unit 134 demodulates the data mapped on the IQ plane output from the OFDM signal demodulation unit 133.
- Demodulation section 103 outputs the demodulated data obtained by demodulation to decoding section 135.
- the decoding unit 135 performs error correction decoding on the input demodulated data.
- a processing circuit such as a subsequent CPU performs a predetermined process using the decoded data obtained as a result.
- the OFDM signal demodulator 133 of the communication system using this OFDM system channel estimation processing for channel compensation is performed.
- the channel estimation value obtained in the frequency domain can be converted into the time domain, and the accuracy of the channel estimation value can be improved by noise suppression processing in the time domain.
- IFFT Inverse Fast
- FFT Fast Fourier transform
- IFFT inverse FFT
- Patent Document 1 discloses a method for suppressing noise included in a channel estimation value in a time domain in channel estimation in wireless communication in which communication is performed using a large number of subcarriers.
- a channel estimation value obtained from a pilot signal mapped to each subcarrier is assumed to be in the frequency domain, and an inverse Fourier transform is performed to convert this into a channel estimation value in the time domain.
- Fourier transform is used to convert the channel estimation value after noise suppression into a channel estimation value in the frequency domain.
- an object of the present invention is to solve the above-described problems, that is, to provide a receiving apparatus, a receiving method, and a computer program that can reduce operations.
- one aspect of the receiving apparatus of the present invention receives a signal including a frequency domain channel estimation value composed of N (N is a power of 2) data, and converts the channel estimation value to P ( P is log 2 N) times DFT (Discrete) (Fourier Transform)
- a receiving device that obtains a time domain channel estimation value by arithmetic processing, and among N pieces of data forming a frequency domain channel estimation value obtained from a received signal, data that has not been replaced with 0 From the number, among the P DFT calculation processes, the MFT (M is 2 or more and P or less) DFT calculation process for starting the DFT calculation process, and the input to the determined M-th DFT calculation process Input to the M-th DFT calculation process from the generation means for generating a rotor for calculating the data to be calculated, the channel estimation value of the frequency domain obtained from the received signal, and the generated rotor
- a signal including a frequency domain channel estimation value composed of N (N is a power of 2) data is received, and the channel estimation value is P (P is log 2 N).
- a reception method for obtaining a time-domain channel estimation value by performing the DFT operation processing once, and among the N data forming the frequency-domain channel estimation value obtained from the received signal From the number of D DFT calculation processes, M (M is 2 or more and P or less) DFT calculation processes for starting the DFT calculation process are determined, and data input to the determined M th DFT calculation process Is generated, and the data input to the M-th DFT calculation process is calculated from the frequency domain channel estimation value obtained from the received signal and the generated rotor. 1st to Pth DFT operations By performing the management is intended for calculating the time-domain channel estimation values.
- one aspect of the computer program of the present invention receives a signal including a channel estimation value in a frequency domain composed of N (N is a power of 2) data, and converts the channel estimation value to P (P is log 2 N).
- a computer constituting a receiving apparatus that obtains a time-domain channel estimation value by performing DFT arithmetic processing times is not replaced with 0 out of N data forming a frequency-domain channel estimation value obtained from a received signal.
- a decision step for deciding the M (M is 2 or more and P or less) DFT computation process for starting the DFT computation process, and the determined M-th DFT computation process From the generation step of generating a rotator for calculating the data input to, the frequency domain channel estimation value obtained from the received signal, and the generated rotator, A calculation step for calculating data input to the DFT calculation process and a calculation step for calculating a time domain channel estimation value by performing the M-th to P-th DFT calculation processes are performed. ing.
- FIG. 1 is a block diagram showing an example of a configuration of a part for demodulating an OFDM signal of a receiving apparatus.
- the part of the receiving apparatus that demodulates the OFDM signal includes a multiplier 11, a selector 12, a memory 13, a memory 14, a selector 15, a two-point DFT operation unit 16, a rotator generation unit 17, a multiplier 18, and a control unit 19. Configured as follows.
- the multiplier 11 multiplies the input signal and the rotor generated by the rotor generation unit 17 and supplies the product data obtained as a result of the multiplication to the selector 12.
- the rotor will be described later.
- the selector 12 is a selector for selecting the storage destination of the input signal, and supplies the data supplied from the multiplier 11 to the memory 13 or the memory 14 in accordance with an instruction from the control unit 19.
- the memory 13 and the memory 14 are composed of a semiconductor memory or the like, and hold fast Fourier transform input data, output data, or intermediate values.
- the memory 13 and the memory 14 are each configured to store N complex data.
- the input data of the fast Fourier transform includes the product of the input signal and the rotator supplied from the multiplier 11 via the selector 12.
- the selector 15 reads out the output data (fast Fourier transform) of the input data (fast Fourier transform input data or intermediate value) of the two-point DFT computing unit 16 from the memory 13 and the memory 14. This is a selector for switching the write destination of the conversion output data or intermediate value).
- the two-point DFT calculation unit 16 applies the radix-2 DFT calculation to the input data or intermediate value of the fast Fourier transform stored in either the memory 13 or the memory 14 supplied via the selector 15. Then, the result obtained by the calculation is supplied to the multiplier 18.
- the rotor generation unit 17 generates a rotor that multiplies the input signal or the output data from the two-point DFT calculation unit 16.
- the multiplier 18 multiplies the result of the radix-2 DFT operation supplied from the 2-point DFT operation unit 16 and the operator supplied from the rotator generation unit 17, and product data obtained as a result of the multiplication. Is supplied to the other of the memory 13 and the memory 14 via the selector 15 as output data of the fast Fourier transform via the selector 15.
- the other of the memory 13 and the memory 14 is the memory 14 when the memory 13 stores the input data or intermediate value of the radix-2 DFT calculation in the two-point DFT calculation unit 16, and the two points.
- the memory 14 stores the input data or intermediate value of the radix-2 DFT calculation in the DFT calculation unit 16, it is the memory 13.
- the control unit 19 refers to the data number of the channel estimation value that has not been replaced with “0” obtained as a result of the noise suppression, which is input as the noise suppression range, and selects the selector 12, the memory 13, the memory 14, and the selector 15. Controls the two-point DFT calculation unit 16 and the rotator generation unit 17 to select the write destination of the input signal, generate the read or write address of the memory 13 or 14, and control the generation of the rotator In addition, the number of two-point DFT operations, the management or control of the processing stage, and the selection of the reading source of the input data or the writing destination of the output data of the two-point DFT operation are selected.
- FIG. 2 is a diagram illustrating an example of a radix-2 fast Fourier transform operation having a two-point DFT operation as a basic element.
- the circles indicate x (0) to x (15) input data (frequency domain channel estimation data), intermediate values, or X (0) to X (15) output data (time domain). Each channel estimation value).
- the arrows indicate the use of input data, intermediate values, or output data.
- input data or an intermediate value indicated at the base of the arrow is added.
- the rotors W 16 0 to W 16 7 attached below the arrow are multiplied by the input data or the intermediate value indicated by the arrow.
- FIGS. 3 to 6 The same applies to FIGS. 3 to 6 below.
- the base 2 is decomposed into log 2 N DFT operation processing groups.
- log 2 N is set to P.
- Each DFT processing group of P times DFT processing group is called a stage. From the input side, the first stage, the second stage,.
- the Coolie-Tukey-type fast Fourier transform can take two types of configurations, a time thinning type and a frequency thinning type, depending on the method of decomposition into two-point DFT operations.
- a fast Fourier transform which is a frequency thinning type configuration
- a value other than 2 can be adopted as the radix, and a time thinning type configuration can also be adopted.
- FIG. 3 is a diagram showing a two-point DFT operation in a radix-2 fast Fourier transform.
- X ′ (m) The output X ′ (m) of the two-point DFT calculation is obtained by equation (1).
- X ′ (m) and x ′ (m) are complex numbers, and j is an imaginary unit.
- the channel estimation value in the time domain is replaced with “0” by the threshold TH, but in an actual propagation path, the power peak often appears at both ends, and the channel near the center. It has been found that most of the estimated values are replaced with '0'.
- N is a power of 2 of 8 or more.
- the calculation for the channel estimation value replaced with “0” is taken into consideration, and the rotor W is added to the data (input data) at the portion other than “0”.
- the first stage DFT operation can be omitted.
- the FFT processing can be started from the second stage.
- x (0), x (1), x (2), x (3), x (12) without performing the first stage DFT operation.
- the DFT operation of the first and second stages can be omitted by preparing in advance the third stage input by multiplying the data of the part other than “0” by the rotor W. it can.
- Wn ⁇ Wm W (n + m). You only need to multiply the child W once.
- the input data of the third stage in FIG. 5 is indicated by a value obtained by performing deformation using the symmetry of the rotor W shown in Expression (2).
- the first to third stages are prepared by previously preparing the input of the fourth stage by multiplying the data of the part other than “0” by the rotor W.
- the DFT operation can be omitted.
- FIG. 6 it seems that it is necessary to multiply the input of the fourth stage by the rotor W three times, but the rotation is the same as in the first case by modifying the same formula as in the second case. You only need to multiply the child W once.
- ⁇ x (15) ⁇ W 16 13 ⁇ W 16 4 can be transformed as shown in Expression (3) by using the symmetry of the rotor W.
- x (0), x (15), x (0) ⁇ W 16 0 , x, without performing the first stage to third stage DFT operations.
- ⁇ W 16 12 , x (0), x (15) ⁇ W 16 10 , x (0) ⁇ W 16 0 , x (15) ⁇ W 16 10 , x (0) ⁇ W 16 0 , x (15) ⁇ W 16 9, x (0) ⁇ W 16 0, x (15) ⁇ W 16 11, x (0) ⁇ W 16 0, x (15) ⁇ W 16 13, x (0) ⁇ W 16 0 , x (15) ⁇ W 16 1 is obtained and input to the fourth stage.
- the DFT calculation for the S stage (S-1) The multiplication of the rotors for the stages can be reduced.
- S ⁇ 1,..., P ⁇ 1 ⁇ .
- step S11 the control unit 19 selects the storage destination of the input signal from the previous stage, for example, selects the memory 13 as the storage destination of the input signal from the previous stage. Then, the control unit 19 acquires, as the noise suppression range, the number of data of the channel estimation value that has been input from the previous stage and has not been replaced with “0” obtained from the result of noise suppression.
- address a the write address to the memory 13 when performing FFT processing from the first stage
- S stage the stage that is the actual process start stage
- address a ′ the write address to the memory 13 when performing FFT processing from the first stage
- step S12 the control unit 19 determines a processing start stage (S-th stage) from the number of data of channel estimation values that have not been replaced with “0”.
- step S ⁇ b> 13 the rotator generation unit 17 generates a rotator W necessary for calculating input data to the determined process start stage.
- step S14 the control unit 19 switches the selector 12 so that the data from the multiplier 11 is supplied to the memory 13.
- the multiplier 11 calculates the data of each address a ′ of the processing start stage from the channel estimation value after noise suppression and the rotator, and supplies the calculated data to the memory 13 via the selector 12.
- the memory 13 writes and stores data supplied from the multiplier 11 therein.
- the address a is converted into the address a ′ by the control unit 19, and the control unit 19 controls the rotator generation unit 17 according to the value of the address a to perform appropriate rotation.
- a child is generated, and a value obtained by multiplying the rotor and the input signal by the multiplier 11 is written in the address a ′ of the memory 13.
- the address a that is 0 is rotated to the address a ′ that is 0 and 1 Child W corresponds.
- the address a that is 1 corresponds to the address a ′ that is 1 and the rotor W that is 1, and as shown in the third line from the top, 14
- the address a ′ that is 2 corresponds to the address a ′ that is 2 and the rotor W that is 1, and as shown in the fourth row from the top, the address a that is 15 corresponds to the address a ′ and 1 that is 3 A certain rotor W corresponds.
- the address a that is 0 corresponds to the address a ′ that is 4 and the rotor W that is W 160
- the address a ′ being 1 corresponds to the address a ′ being 5 and the rotor W being W 16 2
- the rotor W which is W 16 12 corresponds to the address a which is 15 and the rotor W which is W 16 10 as shown in the eighth line from the top.
- the address a that is 0 corresponds to the address a ′ that is 8 and the rotor W that is W 16 0
- the address a ′ being 1 corresponds to the address a ′ being 9 and the rotor W being W 16 1
- the rotor W as W 16 10 corresponds to the address a as 15
- the rotor W as W 16 9 corresponds to the address a as 15.
- the address a being 0 corresponds to the address a ′ being 12 and the rotor W being W 16 0
- Address a ′ being 1 corresponds to address a ′ being 13 and rotor W being W 16 3
- address a being 14 is address a ′ being 14.
- the rotor W which is W 16 10 corresponds to the address a which is 15 and the rotor W which is W 16 13 , as shown in the 16th line from the top.
- the processing start stage is the third stage. Therefore, when the input signal is written into the memory 13, the address a shown in FIG. 8 is converted to the address a ′ shown in FIG. 8 by the control unit 19, and the control unit 19 further converts the address a according to the value of the address a. Then, the rotator generation unit 17 is controlled to generate an appropriate rotator shown in FIG. 8, and the multiplier 11 writes a value obtained by multiplying the rotator and the input signal into the address a ′ of the memory 13.
- step S ⁇ b> the memory 13, the memory 14, the selector 15, the two-point DFT calculation unit 16, the rotator generation unit 17, and the multiplier 18 are written in the memory 13 under the control of the control unit 19.
- the DFT calculation processing from the processing start stage to the final P-th stage is performed based on the received data, and the FFT processing ends.
- control unit 19 reads the selector 15 from the memory 13 in which the input signals are stored and switches to the direction in which the data is written in the memory 14. Thereafter, the control unit 19 starts FFT calculation processing from the S-th stage and performs processing up to the P-th stage. In the process from the S stage to the P stage, the control unit 19 operates the selector 15 so that the result of the previous stage is read from the next stage after the process of each stage is completed.
- the number of data of the channel estimation value that has not been replaced by “0” is equal to or greater than (N / 2 S + 2 + 1) at both ends (N / 2).
- ( S + 1 ) or less the DFT calculation for S stages and the multiplication of the rotor for (S-1) stages can be reduced.
- the center part of the channel estimation value in the time domain becomes “0” in many cases, and this is used to convert the channel estimation value after noise suppression into the frequency domain.
- the amount of FFT processing for conversion can be reduced.
- the channel estimation value after noise suppression is converted from the time domain to the frequency domain. Can be realized at high speed. By omitting unnecessary calculations, a reduction in processing amount can be realized.
- the FFT processing amount can be reduced by devising the FFT stage processing instead of controlling the write destination and the multiplication of the rotor when the input signal is stored in the memory 13 or the memory 14. Can be realized.
- FIG. 9 is a block diagram showing an example of a configuration of a part for demodulating an OFDM signal of a receiving apparatus according to another embodiment of the present invention.
- the parts for demodulating the OFDM signal of the receiving apparatus shown in FIG. 9 include a selector 21, a memory 22, a memory 23, a selector 24, a two-point DFT calculation unit 25, a rotator generation unit 26, a multiplier 27, and a control unit 28. Configured to include. In the part for demodulating the OFDM signal of the receiving apparatus shown in FIG. 9, there is no equivalent to the multiplier 11 in FIG.
- the selector 21 is a selector for selecting the storage destination of the input signal, and supplies the data supplied from the previous stage to the memory 22 or the memory 23 in accordance with an instruction from the control unit 28.
- the memory 22 and the memory 23 are composed of a semiconductor memory or the like, and hold fast Fourier transform input data, output data, or intermediate values.
- the memory 22 and the memory 23 are each configured to store N complex data.
- the selector 24 switches the reading destination and the writing destination of the two-point DFT calculation unit 25 from the memory 22 and the memory 23 in the calculation process of the fast Fourier transform.
- the two-point DFT calculation unit 25 applies the radix-2 DFT calculation to the input data or intermediate value of the fast Fourier transform stored in either the memory 22 or the memory 23 supplied via the selector 24. Then, the result obtained by the calculation is supplied to the multiplier 27.
- the rotor generator 26 generates a rotor W that is multiplied by the output data of the two-point DFT calculator 25.
- the multiplier 27 multiplies the result of the radix-2 DFT operation supplied from the 2-point DFT operation unit 25 by the operator supplied from the rotator generation unit 26, and product data obtained as a result of the multiplication. Is supplied to the other of the memory 22 and the memory 23 as output data of the fast Fourier transform via the selector 24.
- the other of the memory 22 and the memory 23 is the memory 23 when the memory 22 stores the input data or intermediate value of the radix-2 DFT calculation in the two-point DFT calculation unit 25.
- the memory 23 stores the input data or intermediate value of the radix-2 DFT calculation in the DFT calculation unit 25, it is the memory 22.
- the control unit 28 refers to the data number of the channel estimation value that has not been replaced by “0” obtained as a result of noise suppression, which is input as the noise suppression range, and selects the selector 21, the memory 22, the memory 23, the selector 24, Controls the two-point DFT calculation unit 25 and the rotator generation unit 26, selects a writing destination of the input signal, generates a read or write address of the memory 22 or the memory 23, and controls generation of the rotator
- the input signal is stored in the memory 22 or the memory 23 in the same manner as when performing FFT from the first stage. In the following description, it is assumed that the input signal is stored in the memory 22.
- the FFT processing is performed from the S-1 stage.
- the 2-point DFT calculation unit 25 outputs the data read from the address a of the memory 22 without performing the 2-point DFT calculation.
- the control unit 28 controls the rotator generation unit 26 according to the value of the address a, generates an appropriate rotator, and multiplies the value read from the rotator and the data read from the address a of the memory 22 to the address of the memory 23. Write to a '.
- control unit 28 switches the selector 24 to the direction of reading from the memory 23 and writing to the memory A22.
- step S15 Since the processing from the S stage is the same as the processing described with reference to the flowchart of FIG. 7 (procedure of step S15), description thereof is omitted.
- the series of processes described above can be executed by hardware or software.
- the computer program that constitutes the software can perform various functions by installing a computer embedded in dedicated hardware or various computer programs.
- a general-purpose personal computer that can be executed is installed from a computer program recording medium.
- FIG. 10 is a block diagram showing an example of the hardware configuration of a computer that executes the above-described series of processes using a computer program.
- CPU Central A processing unit (61) 61, a ROM (Read Only Memory) 62, and a RAM (Random Access Memory) 63 are connected to each other by a bus 64.
- ROM Read Only Memory
- RAM Random Access Memory
- the input / output interface 65 is connected to the bus 64.
- the input / output interface 65 includes an input unit 66 including a keyboard, a mouse, and a microphone, an output unit 67 including a display and a speaker, a storage unit 68 including a hard disk and a non-volatile memory, and a communication unit 69 including a network interface.
- a drive 70 for driving a removable medium 71 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is connected.
- the CPU 61 loads the computer program stored in the storage unit 68 to the RAM 63 via the input / output interface 65 and the bus 64 and executes the computer program. A series of processing is performed.
- the computer program executed by the computer (CPU 61) is, for example, a magnetic disk (including a flexible disk), an optical disk (CD-ROM (Compact Disc-Read Only Memory), DVD (Digital Versatile Disc), etc.), a magneto-optical disc, or It is recorded on a removable medium 71 that is a package medium made of a semiconductor memory or the like, or provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.
- the computer program can be installed in the computer by storing the removable medium 71 in the drive 70 and storing it in the storage unit 68 via the input / output interface 65. Further, the computer program can be installed in the computer by being received by the communication unit 69 via a wired or wireless transmission medium and stored in the storage unit 68. In addition, the computer program can be stored in advance in the computer by storing it in the ROM 62 or the storage unit 68 in advance.
- the program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.
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Abstract
Description
本発明は受信装置および受信方法、並びにコンピュータプログラムに関する。
Frequency Division Multiplexing)が用いられている。地上波デジタル放送、無線LAN(Local Area
Network)をはじめとし、移動体通信においても、3GPP(3rd Generation
Partnership Project)において、新しい通信方式での標準化が進められているLTE(Long Term
Evolution)でも、OFDMが採用されている。
redundancy check)を付加し、畳み込み符号化を施す。変調部112は、入力された符号データを変調する。OFDM信号生成部113は、変調後のデータを周波数軸上にマッピングし、デジタルフーリエ逆変換によって周波数軸上のデータを時間軸上のデータに変換し、変換後のデータをD/A(Digital Analog)変換部114に出力する。D/A変換部114は、OFDM信号生成部113から出力された変換後のデータをデジタル信号からアナログ信号に変換する。そしてアナログ信号に変換された変調データは複数のアンテナ115を介して送信される。
Fourier Transform)およびFFT(Fast Fourier Transform)がそれぞれ1回ずつ必要となる。デジタル信号のフーリエ変換については、演算量削減のために高速フーリエ変換(FFT)、その逆変換である逆FFT(IFFT)アルゴリズムが用いられるのが一般的である。
Fourier Transform)演算処理によって時間領域のチャネル推定値を求める受信装置であって、受信した信号から求められた周波数領域のチャネル推定値をなすN個のデータのうち、0で置き換えられなかったデータの数から、P回のDFT演算処理のうち、DFT演算処理を開始するM(Mは2以上P以下)回目のDFT演算処理を決定する決定手段と、決定されたM回目のDFT演算処理に入力されるデータを演算するための回転子を生成する生成手段と、受信した信号から求められた周波数領域のチャネル推定値と、生成された回転子とから、M回目のDFT演算処理に入力されるデータを計算する計算手段と、M回目からP回目のDFT演算処理を行うことで、時間領域のチャネル推定値を演算する演算手段とを有するものとされている。
・・・(2)
=-x(15)・W16 1
=x(15)・W16 15
・・・(3)
Processing Unit)61,ROM(Read Only Memory)62,RAM(Random Access Memory)63は、バス64により相互に接続されている。
Claims (6)
- N(Nは2のべき乗)個のデータからなる周波数領域のチャネル推定値を含む信号を受信し、上記チャネル推定値をP(Pはlog2N)回のDFT(Discrete
Fourier Transform)演算処理によって時間領域のチャネル推定値を求める受信装置において、
受信した信号から求められた周波数領域の上記チャネル推定値をなすN個のデータのうち、0で置き換えられなかったデータの数から、P回のDFT演算処理のうち、DFT演算処理を開始するM(Mは2以上P以下)回目のDFT演算処理を決定する決定手段と、
決定されたM回目のDFT演算処理に入力されるデータを演算するための回転子を生成する生成手段と、
受信した信号から求められた周波数領域の上記チャネル推定値と、生成された回転子とから、M回目のDFT演算処理に入力されるデータを計算する計算手段と、
M回目からP回目のDFT演算処理を行うことで、時間領域のチャネル推定値を演算する演算手段と
を有することを特徴とする受信装置。 - 請求項1に記載の受信装置において、
OFDM(orthogonal frequency division multiplexing)方式の信号を受信する
ことを特徴とする受信装置。 - 請求項1に記載の受信装置において、
DFT演算処理に入力されるデータを記憶するメモリをさらに備え、
前記計算手段は、前段から入力された周波数領域の上記チャネル推定値と、生成された回転子とから、M回目のDFT演算処理に入力されるデータを計算し、
前記メモリは、計算されたM回目のDFT演算処理に入力されるデータを記憶する
ことを特徴とする受信装置。 - 請求項1に記載の受信装置において、
第1のメモリと第2のメモリをさらに備え、
前記第1のメモリは、前段から入力された周波数領域の上記チャネル推定値を記憶し、
前記計算手段は、前記第1のメモリに記憶されている上記チャネル推定値と、生成された回転子とから、M回目のDFT演算処理に入力されるデータを計算し、
前記第2のメモリは、計算されたM回目のDFT演算処理に入力されるデータを記憶する
ことを特徴とする受信装置。 - N(Nは2のべき乗)個のデータからなる周波数領域のチャネル推定値を含む信号を受信し、上記チャネル推定値をP(Pはlog2N)回のDFT演算処理によって時間領域のチャネル推定値を求める受信方法において、
受信した信号から求められた周波数領域の上記チャネル推定値をなすN個のデータのうち、0で置き換えられなかったデータの数から、P回のDFT演算処理のうち、DFT演算処理を開始するM(Mは2以上P以下)回目のDFT演算処理を決定し、
決定されたM回目のDFT演算処理に入力されるデータを演算するための回転子を生成し、
受信した信号から求められた周波数領域の上記チャネル推定値と、生成された回転子とから、M回目のDFT演算処理に入力されるデータを計算し、
M回目からP回目のDFT演算処理を行うことで、時間領域のチャネル推定値を演算する
ことを特徴とする受信方法。 - N(Nは2のべき乗)個のデータからなる周波数領域のチャネル推定値を含む信号を受信し、上記チャネル推定値をP(Pはlog2N)回のDFT演算処理によって時間領域のチャネル推定値を求める受信装置を構成するコンピュータに、
受信した信号から求められた周波数領域の上記チャネル推定値をなすN個のデータのうち、0で置き換えられなかったデータの数から、P回のDFT演算処理のうち、DFT演算処理を開始するM(Mは2以上P以下)回目のDFT演算処理を決定する決定ステップと、
決定されたM回目のDFT演算処理に入力されるデータを演算するための回転子を生成する生成ステップと、
受信した信号から求められた周波数領域の上記チャネル推定値と、生成された回転子とから、M回目のDFT演算処理に入力されるデータを計算する計算ステップと、
M回目からP回目のDFT演算処理を行うことで、時間領域のチャネル推定値を演算する演算ステップと
を含む処理を行わせるコンピュータプログラム。
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CN103270711A (zh) | 2013-08-28 |
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