WO2007136036A1 - Ofdm復調装置 - Google Patents
Ofdm復調装置 Download PDFInfo
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- WO2007136036A1 WO2007136036A1 PCT/JP2007/060378 JP2007060378W WO2007136036A1 WO 2007136036 A1 WO2007136036 A1 WO 2007136036A1 JP 2007060378 W JP2007060378 W JP 2007060378W WO 2007136036 A1 WO2007136036 A1 WO 2007136036A1
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0001—Arrangements for dividing the transmission path
- H04L5/0003—Two-dimensional division
- H04L5/0005—Time-frequency
- H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
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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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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/003—Arrangements for allocating sub-channels of the transmission path
- H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
Definitions
- the present invention relates to a demodulator used for digital broadcasting using an Orthogonal Frequency Division Multiplexing (OFDM) system, and more particularly to a technique for improving reception performance in OFDM demodulation.
- OFDM Orthogonal Frequency Division Multiplexing
- DVB-T Digital Video Broadcasting Terrestrial
- ISDB-T Integrated Services Digital Broadcasting Terrestrial
- the OFDM scheme is a type of multi-carrier modulation scheme, in which digital information is transmitted by modulating a large number of carriers having a frequency relationship orthogonal to each other for each symbol.
- a scattered pilot (SP) signal having a known amplitude and phase is arranged for every 12 carriers in one symbol.
- This SP signal is arranged with the frequency arrangement shifted by 3 carriers for each symbol, and the time arrangement is 4 symbol periods.
- the differential detection segment does not include the SP signal (see Patent Document 1).
- an SP signal is extracted from a synchronous detection segment, the SP signal is interpolated in the frequency axis direction and the time axis direction, and the channel characteristics are estimated.
- the received signal is equalized by dividing the information transmission signal by the characteristic (see Patent Document 1).
- Patent Document 2 Pamphlet of International Publication No. 99Z01956
- Patent Document 2 JP 2004-96703 A
- SP signal interpolation methods for example, a method suitable for a fixed reception environment and a method suitable for a mobile reception environment are conceivable. If these multiple SP interpolation methods are implemented in a single OFDM demodulator, the entire system will become large unless resources are shared.
- An object of the present invention is to provide an OFDM demodulator capable of implementing a plurality of SP interpolation methods while reducing an increase in LSI area by effectively using a memory. Means for solving the problem
- the OFDM demodulator when the received signal is in synchronous mode, the SP signal has a predetermined symbol interval in the time axis direction and a predetermined carrier interval in the frequency axis direction. And receiving an OFDM signal in which a continuous pilot signal and a control information signal are arranged at a predetermined carrier position and an information transmission signal is arranged in other parts, and the OFDM signal is subjected to a fast Fourier transform (Fast Fourier Transform). : FFT) FFT circuit, signal power SP signal after fast Fourier transform extraction, and the signal indicating the position of the SP signal on the transmitting side of the extracted SP signal is added as a trigger.
- FFT fast Fourier transform
- a circuit a memory for temporarily storing the SP signal and the information transmission signal to which the positive and negative signs are added, an SP signal to which the sign is added are interpolated in the time axis direction, and the interpolated data and the SP signal are interpolated.
- a carrier interpolator circuit that compensates in the frequency axis direction by inserting “0” between the interpolated data and the next interpolated data according to the P interpolation method, and performing digital filter processing;
- a complex division circuit that complex-divides the information transmission signal by the interpolated data, a timing when a predetermined number of SP signals to which the sign is added are arranged, a timing when the interpolated data is output, and other necessary predetermined timings
- a memory IF interface
- the present invention it is possible to improve the reception rate in various reception states with low power consumption and a small area.
- mobile reception performance is improved by performing equalization processing that can suppress performance degradation at the edge, which is a drawback of using diagonal interpolation processing.
- FIG. 1 is a schematic configuration diagram of an OFDM demodulator according to the present invention.
- FIG. 2 is another schematic configuration diagram of an OFDM demodulator according to the present invention.
- FIG. 3 is a flowchart showing the internal processing of the carrier interpolation circuit in FIGS. 1 and 2.
- FIG. 4 is an image diagram showing the time when the first time interpolation (TF) in FIG. 3 is selected.
- FIG. 5 is an image diagram showing one edge processing mode when second time interpolation (SF2) in FIG. 3 is selected.
- FIG. 6 is an image diagram showing another end processing mode when the second time interpolation (SF2) in FIG. 3 is selected.
- FIG. 7 is a diagram showing area division of the SP memory according to the present invention.
- FIG. 8 is a diagram showing area division of the data memory according to the present invention.
- FIG. 9 is a diagram showing clock division of the SP memory and the data memory according to the present invention.
- FIG. 10 is a detailed explanatory diagram of the memory IF and carrier interpolation circuit in FIG. 1.
- FIG. 11 is a detailed explanatory diagram in a case where one form with the memory IF and the carrier interpolation circuit of FIG. 10 is adopted.
- FIG. 12 is a status transition diagram of the SP request generation circuit in FIG.
- FIG. 13 is a diagram showing pointer control at the time of memory reading in the processing of FIG.
- FIG. 14 is a diagram showing pointer control at the time of memory reading in the processing of FIGS. 5 and 6.
- FIG. 15 is a detailed explanatory diagram of the frequency filter in FIG.
- FIG. 16 is a diagram showing a modification of the two filters in FIG.
- FIG. 17 is a flowchart showing the operation of the circuit of FIG.
- FIG. 1 shows a schematic configuration of an OFDM demodulator according to the present invention, in particular, a configuration of a received signal equalization processing circuit.
- 1 includes an FFT circuit 100, an SP extraction circuit 101, a complex division circuit 102, a carrier interpolation circuit 103, a mode discrimination circuit 200, a memory 300, a memory IF301, and a phase determination circuit. 400 and a phase generation circuit 401.
- the received signal selected by the tuner unit is down-converted to a predetermined band, and after further AZD conversion, is input to the data power FFT circuit 100 that has been subjected to quadrature detection.
- the FFT circuit 100 converts the input data into the frequency domain. All data (including the SP signal) output from the FFT circuit 100 is input to the memory IF 301 through the mode determination circuit 200. The path through which all data passes is defined as the information transmission signal path.
- a part of all data (SP signal) output from the FFT circuit 100 is also extracted by the SP extraction circuit 101, and the output data power of the FFT circuit 100 is extracted to the memory IF301 via the phase determination circuit 400. Entered. This is the SP signal path. All the data input to the memory IF301 is stored in the memory 300.
- the mode discriminating circuit 200 determines whether the mode is a synchronous mode or a differential mode, or the number of propagation carriers.
- the OFDM input information is determined according to information from a circuit means (not shown), and the determination result is transmitted to the memory IF 301.
- the memory IF 301 determines the number of data storage areas in the memory 300, the pointer of the data storage area, the pointer at the time of input / output of transfer data, the number of output data, the output timing, etc. according to the information received from the mode determination circuit 200. adjust.
- the phase (0 or ⁇ ) of the SP signal is predetermined on the transmission side, and the value is obtained based on a predetermined sequence. It is the phase generation circuit 401 that manages this sequence and generates a signal that determines the phase of the SP signal. Using the signal generated by the phase generation circuit 401, the phase is added to the SP signal. Phase determination circuit 400. Specifically, the phase determination circuit 400 aligns the phases of the SP signals by rotating or inverting the sign. The SP signals whose phases are aligned in this way are stored in the memory 300 through the memory IF301.
- the SP signal after the phase is aligned and the SP signal before the information transmission signal and the phase are aligned coexist in the memory 300, depending on the mode.
- the data stored in the memory 300 through the SP signal path, that is, the SP signal after the phases are aligned is input to the carrier interpolation circuit 103 at a predetermined timing. Interpolation processing is performed.
- the data stored in the memory 300 after passing through the path of the information transmission signal, that is, the SP signal before the phase is aligned with the information transmission signal is synchronized with the timing when the processing of the carrier interpolation circuit 103 is completed. It is sent from IF301 to complex division circuit 102.
- the complex division circuit 102 performs complex division for equalization processing of the received signal.
- FIG. 2 shows another schematic configuration of the OFDM demodulator according to the present invention.
- the apparatus shown in FIG. 2 includes a mode discriminating circuit 200, a memory 300, a memory IF 301, and an SP generating circuit 402 in addition to the FFT circuit 100, the complex division circuit 102, and the carrier interpolation circuit 103.
- the memory IF 301 acquires the SP signal before the phase is aligned from the memory 300 and passes it to the SP generation circuit 402.
- the SP generator circuit 402 stores the SP signal read from the memory 300 and before the phase is aligned. This is a circuit for discriminating what symbol and which number of SP signal from the address and the counter value held in the SP generation circuit 402 and aligning the phase of the SP signal.
- the SP signals whose phases are thus aligned are sent to the carrier interpolation circuit 103 and processed in the same manner as in FIG.
- FIG. 3 shows an example of the algorithm of the carrier interpolation circuit 103 in FIGS. 1 and 2.
- “mod ea ” is information for specifying the time interpolation method of the carrier interpolation circuit 103. Based on this information, for example, the first time interpolation (TF) method or the second time interpolation (SF2) is used. A method is selected.
- “Modeb” is information that specifies whether or not to change the edge processing of the SF2 system.
- the coefficient Z input adjustment of the FIR (Finite Impulse Response) filter included in the carrier interpolation circuit 103 is performed according to the selected time interpolation method. For example, when TF is selected, the memory IF301 switches to TF, and the calculation and FIR filter coefficients, the data output order from the memory I F301, the data output timing, and the data input timing to the FIR filter are adjusted. Frequency interpolation using an FIR filter is performed.
- FIR Finite Impulse Response
- FIG. 4 shows the time when TF is selected
- FIG. 5 shows one edge processing mode when SF2 is selected
- FIG. 6 shows the other edge processing mode when SF2 is selected.
- the vertical axis represents the time axis direction
- the horizontal axis represents the frequency axis direction
- all data positions and SP signal positions are indicated by circles.
- the data at the position indicated by the diagonal line pattern is first interpolated from the two SP signals indicated by the black circles, and then the FIR included in the carrier interpolation circuit 103 By passing through the filter, all data positions are interpolated. For example, using the second SP signal (SPA) from the top left and the third SP signal (SPB) from the top left, the data located immediately below the second SP signal at the top left (SPB) ( IPC) interpolating ⁇ ,
- SPA second SP signal
- SPB third SP signal
- IPC (3/4) X SPA + (l / 4) X SPB... [1] The following weighting is performed.
- the weighting factor may be different for each system.
- the carrier interpolation circuit 103 detects the end, and as shown in FIG. 6, the TF method as shown in FIG. Each SF2 method is adopted.
- the process shown in Fig. 5 is performed.
- the data after passing through the FIR filter the data generated from the edge interpolation data is replaced with the data before passing through the FIR filter.
- the memory 300 in FIGS. 1 and 2 has an SRAM (Static Random Access Memory) area divided into a plurality of parts as shown in FIGS. Fig. 7 shows the SP memory area division, and Fig. 8 shows the data memory area division.
- SRAM Static Random Access Memory
- FIGS. 7 and 8 the memory 300 is shared so that it is possible to switch between x2 system at lseg and 3s eg.
- Pointer generation differs depending on the mode and the interpolation method in synchronous mode. Since the number of carriers used and the access method differ depending on the mode, the number of memory areas, the maximum address in one area, and the number of used memories in some cases vary. Figure 8 shows. [0031] Note that since there is no SP signal in the differential mode, the entire area of the memory 300 is used for storing data with a pass power of the information transmission signal, the carrier interpolation circuit 103 is not used, and all data is complex. It is output to the division circuit 102. This mode is determined in advance before the memory IF 301 is expected to operate normally.
- FIG. 9 shows clock division of the SP memory and the data memory.
- an unused SRAM area may appear in the SRA M area in FIG.
- the clock system is divided as shown in Fig. 9, and the clock supply to unused SRAM is stopped when the mode is selected.
- ramclk—xl and x2 operate during X branch operation at lseg and 3 seg
- ramclk—yl and y2 operate during y branch operation at lseg and 3 seg. Operate. If you don't handle the largest amount of data at 3se g! /, It works with ramclk—xl and x2 and ramclk—yl and y2 in mode (all segments are synchronous in mode3) All SRAM that does is used. Adopting such a sharing method is expected to have a significant effect on reducing SRAM usage and power consumption.
- FIG. 10 is a diagram showing details of the memory IF 301 and the carrier interpolation circuit 103 in FIG. 1, and shows connections when SF 2 is selected.
- 3010 in FIG. 10 is an SRAM area image divided into a plurality of areas as shown in FIGS. 7 and 8, and each area has an address offset. In the case of SP memory, one symbol per area. The minute SP signal is stored.
- Memory IF301 includes SRAMIF3011, arbiter 3012, SP request generation circuit 3013, phase alignment circuit 3014, nother 3015, Sym-N counter 3017, C counter 3019, P counter 3020, N A counter 3021, a talent selector 3022, a data / SP write requester 3023, and a data request generation circuit 3024 are provided.
- the carrier interpolation circuit 103 includes a frequency filter 1030, a first time interpolation circuit 3016, and a second time interpolation circuit 3018.
- the memory IF301 includes (1) a function for creating an input data write request signal for the path of the information transmission signal and the SP signal, and (2) a read request signal for data stored from the path of the information transmission signal. (3) SP signal path force Stored data read request signal creation function, (4) Function (1) (2) (3) Access request arbitration function, ( 5) Supplement (6) Address pointer creation function of SRAM3010, (7) Actual access control function of SRAM3010, (3) 8) The buffer function that reserves the data before output to the carrier interpolation circuit 103 is required.
- Function (1) is data ZSP write requester 3023
- function (2) is data request generator 3024
- function (3) is SP request generator 3013
- function (4) is arbiter 3012 (5) is based on phase matching circuit 3014
- function (6) is Sym-N force counter 3017, C counter 3019, P counter 3020, N counter 3021 and offset selector 3022 [From here, (7) ⁇ or SRAMIF3011 [From here] (8) ⁇ MA NOFFA 3015 [Each of these will be realized.
- the memory access request generated by the data ZSP write requester 3023, the data request generation circuit 3024, and the SP request generation circuit 3013 is arbitrated by the arbiter 3012 and transmitted to the SRAMIF 3011.
- the request arbitrated by the arbiter 3012 is the writing power of the path power of the information transmission signal, the writing power from the SP signal path, the path power of the information transmission signal, the reading power of the stored data, and the path power of the SP signal It is determined whether the read data is to be read, and the pointer corresponding to the determined result is obtained from the Sym—Repulsive counter 3017, C counter 3019, P counter 3020, N counter 3021 and offset selector 3022. To access.
- the offset selector 3022 stores the start address of each SRAM area that changes depending on the mode.
- the value of the P counter 3020 that indicates the area that is the center of access, and a predetermined SP signal arrangement.
- the top of the SRAM area is selected according to the value of the Sym-N counter 3017 having a value of 0 to 3 that exists to indicate the pattern of.
- the C counter 3019 is a counter used in the time interpolation method shown in FIG. 4, determines the coefficient in the first time interpolation circuit 3016, and changes depending on the Sym-N counter 3017.
- Data is stored in SRAM3010 through SRAMIF3011, and data ZSP is written. This is performed when the arbiter 3012 receives a write request made in accordance with the timing at which the requester 3023 writes a signal.
- This area-divided image is effective in the synchronous mode and is used as a data memory when switched to the differential mode. At that time, unused data is protected in the synchronous mode. When returning from differential mode to synchronous mode, unused data is similarly protected.
- Data reading from the SRAM 3010 is performed according to the following procedure. That is, in the synchronous mode, the SP request generation circuit 3013 sends a data read request to the arbiter 3012 when the SP signal is stored for a predetermined number of areas (that is, a predetermined number of symbols). After the data read request is accepted by the arbiter 3012, data is read through the SRAMIF 3011.
- the data read from the SRAM 3010 is data related to the function (2), it is directly output to the complex division circuit 102. If the data is related to the function (3), it is stored in the buffer 3015 through the phase matching circuit 3014. Then, according to the data input request of the carrier interpolation circuit 103, “VALID” indicating the data valid signal is output to the carrier interpolation circuit 103 at a timing at which irregular transmission is possible.
- the data stored in the noffer 3015 is based on the stored data in the first time interpolation circuit 3016 in one mode, and in another mode.
- the results interpolated by the second time interpolation circuit 3018 are input to the frequency filter 1030.
- the time interpolation processing described here may be before or after data is stored in the notifier 3015. Having this circuit eliminates the need to adjust the data read timing that varies depending on the system for each product type, and also requires phase alignment every time data is read from SRAM 3010 through phase alignment circuit 3014. There is no need to hold data after phase matching, and there is a great merit in small area.
- the feature of the memory IF301 in Fig. 10 is that it has a noffer 3015, and the interaction with the carrier interpolation circuit 103 is made a non-shake access, thereby minimizing the number of accesses related to function (3). There is in point.
- the data timing for the data ZSP write requester 3023 is uniquely determined by the mode, and the data timing for the data request generation circuit 3024 is The arbiter timing is uniquely determined by the mode, interpolation method, and output start timing.
- the mode here refers to all cases determined by the standard, such as the difference between the synchronous mode Z differential mode, lsegZ3seg, etc., and modes I, ⁇ , III, etc. in the standard.
- phase matching circuit 3014 in order to execute the calculation of the above-described equation [1], it is necessary to match the phase of SPA and SPB to the phase that the IPC should originally have. At this time, there is a possibility that the amount of data increases due to the relationship of data accuracy.
- the arithmetic processing for adjusting the phase is output from the memory IF301 and then interpolated like Equation [1]. It is also characterized by the fact that the required amount of SRAM3010 is kept small by being calculated immediately before.
- the horizontal direction (frequency axis direction) is the data output direction to the carrier interpolation circuit 103, and a predetermined number of data determined by the mode exists in one column. After all the horizontal columns have been output, the next lower column in the vertical direction (time axis direction) becomes the next output data for the carrier interpolation circuit 103.
- the data write to the SRAM 3010 related to the function (1) is determined according to the maximum number of areas allocated for the information transmission signal path and the SP signal path.
- An offset address that is uniquely determined in advance is stored in the offset selector 3022 in FIG. 10, and the offset address according to the value of the P counter 3020 that indicates which area is being accessed and the position that is currently being accessed are indicated.
- a value obtained by adding the value of the N counter 30 21 becomes a pointer for writing.
- Reading from the SRAM 3010 related to the function (2) is the same as data writing to the SRAM 3010 related to the function (1).
- the memory IF The data output from 301 is multiplied by a coefficient in the first time interpolation circuit 3016 in the case of the TF method, and in the second time interpolation circuit 3018 in the case of the SF2 method.
- the first and second time interpolation circuits 3016 and 3018 may exist in the memory IF 301, or may be present before storage in the buffer 3015. This is because there is an arithmetic processing after reading from the SRAM 3010.
- the coefficient multiplied and interpolated data is input to the frequency filter 1030. This frequency filter 1030 corresponds to the FIR filter described above.
- the SP signal may be used for purposes other than transmission path characteristic estimation.
- the functions (1) to (3) related to the above-mentioned memory access request it is assumed that there is an SP signal read request for data operation called (3) 'CFI system.
- FIG. 11 is a detailed explanatory diagram when the memory IF 301 and the carrier interpolation circuit 103 in FIG. 10 are in one form
- FIG. 12 is a status transition diagram of the SP request generation circuit 3013 in FIG. is there.
- the readout from the SRAM 3010 related to the function (3) is as shown in FIG. 13 or FIG. 14 depending on the interpolation method.
- FIG. 13 is a diagram showing pointer control at the time of memory reading in the process of FIG. 4 (when TF is selected).
- a P counter 3020 is a loop pointer that returns to a numerical value indicating the first area when the maximum number of areas indicating the reference area for memory access is counted.
- the C counter 3019 is a pointer that indicates from which area the SP signal necessary for interpolation is acquired based on the P counter 3020.
- the C counter 3019 can take a value of 0 to 3, for example.
- C When the value power of the counter 3019 is O, the SP signal is extracted from the SRAM area indicated by the P counter 3020.
- the data SPo from the area immediately preceding the SRAM area indicated by the P counter 3020 and the data SPn of the area immediately before the SRAM area indicated by the C counter 3019 are acquired.
- the operation is performed so that (3/4) X SPn + (1/4) X SPo is output as the interpolation data.
- the N counter 3021 is a pointer indicating which SP signal is to be acquired from the left end of the SP signal as an initial value.
- the force P counter 3020 which is a loop counter that returns to the original value when all the counters make a round, determines the maximum value that can be taken with the predetermined maximum number of SRAM areas as described above. As soon as the read access to the area is completed, the value changes to the next value.
- the N counter 3021 changes for each related memory access, and the maximum number is uniquely determined because the number of SP signals in the horizontal direction is determined by a predetermined mode.
- the C counter 3019 changes for each related memory access and takes four values, which are the values of the Sym-N counter 3017!
- the Sym—N counter 3017 is a pointer that changes every time the N counter 3021 goes around, and indicates the number of symbols (number of symbols) in the vertical direction of the current output data to the carrier interpolation circuit 103.
- the C counter 3019 can also be a pointer indicating the interpolation coefficient and calculation method in the carrier interpolation circuit 103.
- Figure 11 shows that power. The connection is slightly different from Figure 10.
- FIG. 14 is a diagram showing pointer control at the time of memory reading in the processing of FIGS. 5 and 6 (when SF2 is selected).
- the basic idea is the same as in the case of the TF method.
- the C counter 3019 requires the Sym-N counter 3017, P counter 3020, and N counter 3021 values, and the preset offset value in the offset selector 3022. As a result, the readout pointer is uniquely determined.
- the coefficient for interpolation depends on the value of N counter 3021. Exist.
- FIG. 15 is a detailed explanatory diagram of the frequency filter 1030 in FIG.
- a data buffer 10307 having a circuit for handshake access with the memory IF301. If this data buffer 10307 is empty, a data request is always sent to the memory IF301.
- the necessary interpolation data is pre-read, the necessary 0 data is generated between the interpolation data and the interpolation data by the input of the FIR filter by the data selector 10308, and the next interpolation data is sent while sending the 0 data to the FIR filter. Is obtained from the memory IF301! It is characterized in that the transmission timing of interpolation data is relaxed by repeatedly performing data transfer.
- a reception state detector 10311 for detecting a reception state and a mode selection circuit 1 0302 are provided, and one symbol is selected according to the mode selected by the mode selection circuit 10302 according to the reception state.
- the number of SPs, the coefficient of FIR filter, and the number of carriers involved in FIR filter input end processing change.
- a plurality of setting registers included in the mode selection circuit 10302 can be controlled by software.
- the number of SPs per symbol is counted by the N counter 10300, and at the end of one symbol, one symbol end signal is issued by the circuit 10301. Then, every 1 symbol end signal, Sym-N counter 10303 force S changes.
- the Sym-N counter 10303 is a counter indicating the symbol position of the input signal (vertical axis position in FIG. 4).
- One frequency filter 10309 is a narrowband (N) filter
- the other frequency filter 10310 is a wideband (W) filter.
- the filter coefficient is stored in advance in the register 10305 as a fixed value or a variable value by register setting.
- the edge processing is controlled by the edge processing control circuit 10304.
- This end processing control circuit 10 304 has a role of extending the left end of data input to the frequency filters 10309 and 10310 by a predetermined number. The number to be extended depends on the number of taps of the frequency filters 10309 and 10310.
- the data output selection control circuit 10306 instructs the data selector 10308 and the data buffer 10307 in which the memory IF301 input data is also stored. , Determine whether to send 0 data to the frequency filters 10309 and 10310, whether to send the data stored in the data buffer 10307, and instruct the data selector 10308.
- the data selector 1 0308 sends the data to the frequency filters 10309 and 10310 as instructed.
- the results of the frequency filters 10309 and 10310 are sent to the complex division circuit 102, respectively. Note that the ratio between the number of data transmissions from the data buffer 10307 and the number of transmissions of 0 varies depending on the interpolation method.
- FIG. 16 shows a modification of the two finoletas 10309 and 10310 in FIG. 15, and FIG. 17 shows the operation of the circuit in FIG.
- both filters 10309 and 10310 always operate in parallel, and the better result is selected by the complex division circuit 102.
- a main line filter (0) 500 and a test finalizer (1) 501 are provided.
- Reference numerals 502, 503, 504, 505, and 506 denote registers, 507 and U half-cut 508 and 509, respectively.
- the characteristics of the test filter 501 are changed in four ways by four symbols every 16 symbols, and the results are stored in the registers 503, 504, 505 and 506, and the judgment unit 50 7 Choose the best one. Then, the selection result is set in the main line filter 500 via the selector 508, and the selection result is fed back to the test filter 501.
- the main line filter 500 is an adaptive filter, which is substantially equivalent to the case where four filters are used even though the number of filters is two.
- the results of the force test filter 501 in which the main line filter 500 is set are only the results of every 4 symbols.
- the result of every 4 symbols may be added to registers 503 to 506 multiple times (for example, N times: N is 1 to: LOOO times may be selected). Subsequently, the selection result may be set in the main filter 500 every 4 XN symbols.
- a method of selecting the best CN value obtained from the four filter results can be considered.
- There are many calculation methods for CN and depending on the method, under certain circumstances when one symbol is interpolated, an accurate CN value may not be obtained, and a better value than the actual performance may be obtained. In this case, an incorrect filter may be selected. Therefore, when the calculated CN values are added to the registers 503 to 506 for the four filter results, only the value set from the outside is bad. If the value is set, the processing can be performed in the registers 503 to 506!
- the OFDM demodulator according to the present invention can implement a plurality of SP interpolation methods while minimizing an increase in LSI area, and is useful as a terrestrial digital broadcast receiver or the like.
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Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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EP07743812A EP2020771A1 (en) | 2006-05-24 | 2007-05-21 | Ofdm demodulation device |
JP2007549755A JP5032997B2 (ja) | 2006-05-24 | 2007-05-21 | Ofdm復調装置 |
US12/094,364 US8077784B2 (en) | 2006-05-24 | 2007-05-21 | OFDM demodulation device |
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JP2006-143960 | 2006-05-24 | ||
JP2006143960 | 2006-05-24 |
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US (1) | US8077784B2 (ja) |
EP (1) | EP2020771A1 (ja) |
JP (1) | JP5032997B2 (ja) |
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WO (1) | WO2007136036A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009260604A (ja) * | 2008-04-16 | 2009-11-05 | Fujitsu Ltd | 移動局装置及び伝送路推定方法 |
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WO2015058041A1 (en) * | 2013-10-17 | 2015-04-23 | Eon Corporation | Communication synchronization method and system |
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Also Published As
Publication number | Publication date |
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EP2020771A1 (en) | 2009-02-04 |
JPWO2007136036A1 (ja) | 2009-10-01 |
US20090268852A1 (en) | 2009-10-29 |
JP5032997B2 (ja) | 2012-09-26 |
US8077784B2 (en) | 2011-12-13 |
CN101361304A (zh) | 2009-02-04 |
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