Classifications

• • 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
  • H04L27/2626—Arrangements specific to the transmitter only
  • H04L27/2627—Modulators
  • H04L27/2634—Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
  • H04L27/2636—Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• • 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
  • H04L27/26524—Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
  • H04L27/26526—Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation with inverse FFT [IFFT] or inverse DFT [IDFT] demodulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] receiver or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• • 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
  • H04L27/2602—Signal structure
  • H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
  • H04L27/2607—Cyclic extensions

Definitions

• the present invention relates to a radio communication device and a communication method thereof, and more particularly to a radio communication device using frequency diversity and a communication method thereof.
• OFDM Orthogonal Frequency Division Multiplexing
• DFT-SuFDM Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing
• the OFDM system has a problem that the peak-to-average power ratio (PAPR) is high, and this problem is particularly noticeable in the uplink of a wireless communication system.
• PAPR peak-to-average power ratio
• SC-FDMA Single Carrier Frequency Division Multiplexing
• DFT-SOFD M Single Carrier Frequency Division Multiplexing
• PAPR can be suppressed by converting the data to DFT and IDFT.
• FIG. 1 is a block diagram showing a configuration of a conventional DFT-SOFDM system.
• SZP conversion section 101 performs SZP conversion on transmission data
• DFT section 102 performs N-point DFT on the transmission data after S / P conversion, and performs subcarrier mapping.
• Unit 103 maps N points of transmission data after DFT to M points. This is because the number of conversion points in DFT and IDFT is different.
• the IDFT unit 104 performs M-point IDFT on the transmission data mapped to the M point
• the CP adding unit 105 adds CP to the IDFT transmission data
• the P / S conversion unit 106 The transmission data after adding the CP is PZS converted and transmitted from the antenna.
• the SZP conversion unit 108 performs SZP conversion on the data stream that also received the antenna power
• the CP removal unit 109 also removes the CP from the parallel data stream force
• the DFT unit 110 By performing MFT DFT processing, the parallel data stream is converted to time domain power frequency domain, subcarrier demapping unit 111 maps M point data to N points, and IDFT ⁇ to N points.
• N-point IDFT processing By performing N-point IDFT processing on the mapped received data, the N point data is converted to the frequency domain force time domain, and the PZS converter 113 PZS converts the time domain data to receive data. Is generated.
• transmission data in the time domain is converted into the frequency domain by DFT processing, and the frequency domain data is mapped to different subcarriers and transmitted. Data mapped to different subcarriers undergoes different channel fading and are received by the receiving side.
• frequency diversity gain cannot be obtained and transmission characteristics are not improved. is there.
• An object of the present invention is to provide a wireless communication apparatus and a communication method thereof that can improve transmission characteristics using frequency diversity.
• the wireless communication apparatus of the present invention includes a modulation unit that modulates transmission data by a predetermined modulation method to obtain first data, and sets the first data to "0" according to a desired modulation method.
• the same data is different from the insertion means for inserting and generating the second data, and the conversion means for converting the second data from the time domain to the frequency domain to generate the same overlapping data.
• a mapping means for mapping to subcarriers.
• FIG. 1 Block diagram showing the configuration of a conventional DFT-SOFDM system
• FIG. 2 is a table showing a relationship between a modulation scheme according to an embodiment of the present invention and the number of “0” s to be inserted.
• FIG. 3 is a block diagram showing a configuration of a DFT-SOFDM system according to an embodiment of the present invention.
• FIG. 4A is a diagram showing a mapping state according to an embodiment of the present invention.
• FIG. 4B is a diagram showing a mapping state according to the embodiment of the present invention.
• FIG. 5 is an operation flow diagram of a DFT-SOFDM system according to an embodiment of the present invention.
• FIG. 6 is a diagram showing simulation results according to one embodiment of the present invention.
• FIG. 7 is a diagram showing a result of another simulation according to the embodiment of the present invention.
• an equal gain synthesis method ECC
• MMSEC minimum mean square error synthesis method
• MRC maximum ratio synthesis method
• the equal gain combining method is a method of obtaining the output by performing only addition by gain, such as the signal envelope of each subpath, the equal gain combining method does not perform error correction for channel distortion.
• the error in the estimated value of the data signal must be orthogonal to the baseband part of the received signal. Therefore, when the signal is weak, the gain is reduced so that the noise is not amplified. When strong, the gain is proportional to the inverse of the signal envelope.
• each diversity subcarrier is weighted so that the SIR (Signal to Interference Ratio) of the output signal is maximized.
• the gain for each group to be combined is proportional to the signal amplitude, and the SIR of the combined signal is the sum of the SIR of each subcarrier before combining, so the maximum ratio combining method is relatively good! This is a synthesis method.
• FIG. 2 shows the relationship between each modulation method and the number of “0” s to be inserted.
• the (original modulation method) is BPSK, it can be converted to a new modulation method such as QPSK, 16QAM, or 64QAM.
• each symbol occupies 1 bit in the BPSK modulation method, whereas each symbol occupies 2 bits in the QPSK modulation method, so 1 in the symbol after BPSK modulation.
• the data is duplicated twice in the frequency domain (the same data can be created twice) while maintaining the same bit transmission rate.
• each symbol occupies 4 bits in the 16QAM modulation system, by inserting three “0” s into the symbol after BPSK modulation, the data power is duplicated S4 times in the frequency domain (four identical data You can do it.)
• 64QAM modulation method Since each symbol occupies 6 bits in the equation, data is duplicated 6 times in the frequency domain by inserting 5 “0” s into the symbol after BPSK modulation (same data can be created 6 times each) It will be.
• the original modulation scheme of the system is QPSK
• it can be converted to a modulation scheme having a high modulation level such as 16QAM or 64QAM by inserting "0" into the symbol after QPSK modulation.
• each symbol occupies 2 bits in the QPSK modulation method
• each symbol occupies 4 bits in the 16QAM modulation method, so one “0” is assigned to the symbol after QPSK modulation.
• the data is duplicated twice in the frequency domain (the same data can be created twice).
• the 64QAM modulation system occupies 1 ⁇ 2 bit of each symbol power, by inserting two “0” s into the symbol after QPSK modulation, the data is duplicated three times in the frequency domain (three identical data You can do it.)
• Equation (1) becomes ⁇ (0), A (l), ⁇ , ⁇ (2 ⁇ -1) by FFT processing.
• a (k) (0 ⁇ k ⁇ N 1) is shown in the following equation (2), and
• a (k + N) is shown in the following equation (3).
• Equation (4) becomes A (O), A (l), ..., A (N (M + 1) -1) by FFT processing.
• a (k) (0 ⁇ k ⁇ N-l) is shown in the following equation (5)
• a (k + cN) is shown in the following equation (6),
• FIG. 3 is a block diagram showing a configuration of the DFT-SOFDM system according to the present embodiment.
• modulation section 201 modulates transmission data by a predetermined modulation scheme (original modulation scheme in FIG. 2), for example, BPSK, and outputs the modulated data (symbol) to insertion section 202.
• a predetermined modulation scheme original modulation scheme in FIG. 2
• BPSK BPSK
• Insertion section 202 has the number of “0” s corresponding to the desired modulation scheme (new modulation scheme in FIG. 2) so that the transmission rate does not change in the modulated data input from modulation section 201. Insert Desired modulation data is generated, and the modulation data is output to the SZP converter 203. Specifically, for example, when the modulation scheme of the modulation section 201 is BPSK, and when converting to the desired modulation scheme QPSK, the insertion section 202 adds one “0” after each BPSK modulated symbol. insert. Also, for example, when the modulation scheme power of the modulation unit 201 is PSK, and when converting to a desired modulation scheme 16QAM, the insertion unit 202 inserts three “0” s after each BPSK-modulated symbol.
• the SZP conversion unit 203 converts the modulation data input from the insertion unit 202 into parallel and outputs it to the DFT unit 204.
• the DFT unit 204 performs N-point DFT processing on the parallel modulation data input from the SZP conversion unit 203, thereby converting the modulation data into a time domain power frequency domain, and converting the frequency domain data into The data is output to the data mapping unit 205.
• Data mapping section 205 maps N-point frequency domain data to different subcarriers so that the N-point frequency domain data input from DFT section 204 becomes M-point frequency domain data. And output to the IDFT unit 206.
• the mapping by the data mapping unit 205 is shown in FIGS. 4A and 4B.
• mapping section 205 maps data to the subcarriers selected in order (Localized mapping).
• mapping section 205 maps data to subcarriers selected at equal intervals (Distributed mapping). Since Localized mapping is more effective for reducing the PAPR value, Localized mapping is used in this embodiment.
• the IDFT unit 206 performs M-point IDFT processing on the mapped data input from the data mapping unit 205, thereby converting the data from the frequency domain to the time domain, thereby converting the time domain data. Output to CP adding section 207.
• CP adding section 207 adds CP for each block to the time domain data input from IDFT section 206 and outputs the result to PZS converting section 208.
• PZS conversion section 208 converts the CP-added data input from CP adding section 207 into serial data, and outputs the serial data.
• the SZP converter 210 transmits different channel channels via the channels.
• the data subjected to aging is converted into M-point parallel data by SZP conversion and output to the CP removal unit 211.
• CP removing section 211 removes the CP from the parallel data input from SZP conversion section 210 and outputs the result to DFT section 212.
• DFT section 212 performs M-point DFT processing on the data input from CP removing section 211, converts the data into a time domain power frequency domain, and converts the frequency domain data into data demapping section 213. Output to.
• the data demapping unit 213 demaps the frequency domain M point data input from the DFT unit 212 to N points, and outputs the demapped data to the data synthesis unit 214.
• Data combining section 214 combines the same data transmitted by different subcarriers to generate combined data, and outputs the combined data to IDFT section 215. Specifically, when one “0” is inserted in the modulated data on the transmission side, two identical data obtained in the frequency domain are transmitted via different channels, and the maximum is obtained on the reception side. Two identical received data are synthesized by ratio synthesis (MRC) method or other synthesis methods. The two sets of received data are a, a, ..., a and b, b, ..., b, respectively.
• MRC ratio synthesis
• r and r are composite data.
• the IDFT unit 215 performs N-point IDFT processing on the combined data input from the data combining unit 214, thereby converting the data from the frequency domain to the time domain, and converting the time domain data to PZS conversion. Output to part 216.
• the PZS conversion unit 216 converts the time domain parallel data input from the IDFT unit 215 into serial data and outputs the serial data to the removal unit 217.
• the removal unit 217 removes “0” inserted by the insertion unit 202 from the serial data input from the PZS conversion unit 216 and outputs the result to the demodulation unit 218.
• Demodulation section 218 demodulates the data input from removal section 217 and outputs received data.
• FIG. 5 is an operation flow diagram of the DFT-SOFDM system according to the present embodiment.
• transmission data is first modulated by modulation section 201 with a predetermined modulation scheme (ST301), and insertion section 202 adds a desired modulation scheme to the modulated data.
• the SZP converter 203 performs SZP conversion (ST 303), and the DFT unit 204 converts it into frequency domain data by N-point DFT processing (S302). T304), data overlap in the frequency domain.
• the data mapping unit 205 maps the overlapping data in the frequency domain to M different subcarriers selected in order (ST305), and the IDFT unit 206 converts the data into time domain data by IDFT processing of ⁇ points.
• Conversion (ST306), CP adding section 207 adds CP to each data block (ST307), and PZS conversion section 208 converts serial data to parallel data (ST308), and converts antenna force data. Transmit (ST309).
• SZP conversion section 210 performs SZP conversion on the received data subjected to different channel fading (ST310), CP removal section 211 removes CP from the data (ST311), and DFT section 212 has M points.
• the time domain data is converted to frequency domain data (ST312), and the data demapping unit 213 demaps the data to M points and N points (ST313).
• Data combining section 214 combines the same data transmitted by different subcarriers (ST314), and IDFT section 215 converts the frequency domain data into time domain data by N-point IDFT processing (ST315).
• PZS conversion section 216 converts parallel data into serial data (ST316)
• removal section 217 removes “0” from the data according to the modulation scheme of modulation section 201 (ST317)
• demodulation section 218 demodulates the data and And it outputs the data (ST318).
• Fig. 6 indicates the performance of the system using the BPSK modulation method
• ' * indicates the performance of the system using the QPSK modulation method
• ⁇ indicates the performance of the system using the QPSK modulation method
• ⁇ indicates the performance of the system using the QPSK modulation method
• the transmission rate is 1Z2 QPSK modulation method
• the transmission rate is the same for the 1Z2 QPSK modulation method (' ⁇ ') and the conventional BPSK modulation method (' ⁇ ').
• the maximum ratio combining method MRC is used on the receiver side in a system that uses the QPSK modulation method with a transmission rate of 1Z2.
• Fig. 7 “*” indicates the performance of the system using the QPSK modulation method, “+” indicates the performance of the system using the 16QAM modulation method.
• the performance of the system according to the invention is shown.
• the apparatus of the present invention is suitable for a wireless communication system using frequency diversity.

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Citations (2)

• 2006
  • 2006-03-22 CN CNA2006100717861A patent/CN101043485A/zh active Pending
• 2007
  • 2007-03-22 WO PCT/JP2007/055884 patent/WO2007119487A1/ja active Application Filing

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