WO2005101669A1 - パスメモリ回路 - Google Patents
パスメモリ回路 Download PDFInfo
- Publication number
- WO2005101669A1 WO2005101669A1 PCT/JP2004/018194 JP2004018194W WO2005101669A1 WO 2005101669 A1 WO2005101669 A1 WO 2005101669A1 JP 2004018194 W JP2004018194 W JP 2004018194W WO 2005101669 A1 WO2005101669 A1 WO 2005101669A1
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- WO
- WIPO (PCT)
- Prior art keywords
- circuit
- memory
- signal
- state
- storage element
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/65—Purpose and implementation aspects
- H03M13/6502—Reduction of hardware complexity or efficient processing
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/37—Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35
- H03M13/39—Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes
- H03M13/41—Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes using the Viterbi algorithm or Viterbi processors
Definitions
- the present invention relates to a noise memory circuit that stores surviving path information in each state in Viterbi decoding used for communication, a read channel of an optical disk or a magnetic disk.
- Viterbi decoding is a technique for predicting and decoding the most appropriate data based on a convolution rule when a data sequence encoded by a specific convolution is received.
- the convolution rule can be described as a state transition diagram, and if the concept of time is taken into consideration in this state transition diagram, it can be described as a trellis diagram.
- Fig. 1 shows a convolutional encoder
- Fig. 2 shows a trellis diagram corresponding to the convolutional encoder.
- 81 and 82 are delay elements
- 83 and 84 are adders.
- the delay elements 81 and 82 hold the value one time before.
- K in FIG. 2 indicates time. That is, FIG. 2 shows a state transition from time k1 to time k and a state transition from time k to time k + 1.
- SO-S3 indicates a state number in the state transition. A line connecting the states is called a branch, and a state connects to a state to which the next transition can be made.
- a branch metric is calculated using an evaluation function for each branch in order to evaluate the likelihood (probability) of transition from each state.
- each state has the most certain branch among the branches leading to that state, and accumulates and stores the branch metrics of the branch. This is called a path metric.
- the branch metric is calculated by the square error between the ideal value and the actually received value. Is most likely to be a branch.
- a path obtained by such processing and connecting the most probable branches at each time is a surviving path! /.
- Each state in the trellis diagram has its own surviving path, but as the decoding process proceeds, the surviving paths of all the states converge to the same one. Similarly, as the shift operation proceeds, the contents of the path memory circuit converge to the same value in the memory for each state.
- One surviving path obtained in this way is the final decoding result by Viterbi decoding.
- the number of memory stages (memory length) of the path memory circuit is sufficient if there is a number of stages that can hold data until the decoding result converges.
- the time required for convergence varies depending on the use environment, such as the temperature and noise, which cannot be determined only by the code method and applied application. For this reason, in the conventional Viterbi decoding path memory circuit, a longer memory length is used in consideration of a change in the use environment. However, this causes an increase in circuit scale and power consumption.
- reference numeral 20 denotes a selection circuit for selecting an input signal according to the most probable branch determined by each state
- reference numeral 21 denotes a storage element circuit holding an output of the selection circuit 20
- reference numeral 22 denotes a selection storage element circuit
- reference numeral 23 denotes a selection storage element circuit.
- One stage memory circuit, 24 indicates an output selection circuit.
- the storage circuit 23 at the j-th or later stage is supplied with a method such as stopping the supplied clock signal. The operation stops.
- the selection circuit 24 selects and outputs the output of the storage circuit 23 at the j-th stage according to the memory length control signal. In this way, the path memory circuit of FIG. 3 requires only the operation of the storage circuit 23 of the j-th stage, and the power consumption of the storage circuit 23 for the M—j + 1 stage can be reduced.
- Patent Document 3 a method of selecting the input stage to the path memory circuit by allowing the former part to be stopped is also known.
- Patent Document 1 JP-A-63-166332
- Patent Document 2 JP-A-10-302412
- Patent Document 3 JP-A-2002-368628
- An object of the present invention is to realize low power consumption and a reduction in circuit size of a path memory circuit.
- the path memory circuit according to the present invention is capable of stopping the operation of the storage element circuits of the (i + 1) th (i is an integer and 0 ⁇ i ⁇ M) stage or later by a control signal, and
- the memory element circuit that holds data related to a specific state is a memory area B, and the memory element circuits that do not belong to the memory area B among the memory element circuits in the (i + 1) th and subsequent stages are the memory area C and the remaining memory element circuits.
- the storage element circuits belonging to the memory area B are controlled so as to form a shift register.
- the path memory circuit according to the present invention can provide a bus wiring for extracting output from each stage and an output for each output even when the storage element circuits at the j-th stage and thereafter are stopped. It is possible to obtain a path memory output without adding a selector for selecting the path memory, and it has a remarkable effect on realizing low power consumption of the path memory circuit and reduction of the circuit scale.
- FIG. 1 is a block diagram showing a configuration of a general convolutional encoder.
- FIG. 2 is a trellis diagram corresponding to the convolutional encoder in FIG. 1.
- FIG. 3 is a block diagram showing a conventional noise memory circuit having a variable memory length.
- FIG. 4 is a block diagram of a path memory circuit according to the first embodiment of the present invention.
- FIG. 5 is a block diagram showing an example of generating a memory length control signal in FIG. 4.
- FIG. 6 is a block diagram showing another example of generating the memory length control signal in FIG. 4.
- FIG. 7 is a circuit diagram showing a configuration example of a storage element circuit for a memory area B in a path memory circuit according to a second embodiment of the present invention.
- FIG. 8 is a circuit diagram showing a modification of the storage element circuit of FIG. 7.
- FIG. 9 is a circuit diagram showing a method of synchronizing a memory length control signal, which is an alternative to the configurations of FIGS. 7 and 8.
- FIG. 10 is a block diagram of a path memory circuit according to a third embodiment of the present invention.
- FIG. 11 is a block diagram of a path memory circuit according to a fourth embodiment of the present invention.
- FIG. 12 is a circuit diagram showing a configuration example of a storage element circuit in FIG. 11;
- FIG. 4 shows a path memory circuit according to the present invention.
- 1 is the memory area A and 2 is the memory area.
- Memory areas B and 3 are memory areas C and 10
- a selection circuit 11 is a storage element circuit
- 12 is a selected storage element circuit
- 13 is a one-stage storage circuit.
- the selection storage element circuit 12 is a selection circuit 10 that selects and outputs an input signal according to a signal indicating the most probable branch obtained for each state by Viterbi decoding, and uses the output as a clock signal.
- a storage element circuit 11 that holds the data synchronously.
- the storage circuit 13 includes a selection storage element circuit 12 for all states belonging to the same stage.
- the number of the selected storage element circuits 12 is 4M in total.
- the memory area A is an area including the selected storage element circuits 12 for all the states up to the i-th stage required when Viterbi decoding converges fastest.
- the memory area B is an area including the one related to the state 0 in the selected storage element circuits 12 in the (i + 1) th to Mth stages.
- the memory area C is an area including all the other selected storage element circuits 12.
- the selection circuit 10 and the storage element circuit 11 belonging to the memory area A and the memory area C may be a general selector and a general flip-flop or latch, respectively.
- the selection circuit 10 belonging to the memory area B needs to be controlled so as to select an input which belongs to the memory area B among the preceding selected storage element circuits 12 when the operation is stopped.
- the storage element circuit 11 in the memory area B may be a general flip-flop or a latch.
- the selection circuit 10 since the selection circuit 10 always selects the X input, the selected storage element circuits 12 in the jth and subsequent stages of the memory area B shift the output of the preceding stage to the subsequent stage like a shift register. . As a result, the output signal of the j-th stage storage circuit 13 is output as the output of the path memory circuit.
- a normal operation is performed from the (i + 1) th stage to the (j) th stage; Then, the operation is stopped.
- a method of stopping the supply of the clock signal is generally known.
- the clock wiring supplied to the memory area C is separated for each stage, and the corresponding memory length control signal If H is H, control should be performed so that the clock signal is fixed at L or H.
- a reverse bias may be applied to a substrate of a transistor constituting a circuit of a stage where the memory length control signal is H.
- the leakage current can be reduced, so that the power consumption can be further reduced.
- control may be performed such that power supplied to each stage is separated, and power is not supplied to the circuit of the stage that stops operation.
- FIG. 5 shows a memory length control circuit according to such a method.
- 71 is a memory length setting unit
- 72 is an OR circuit.
- the memory length setting unit 71 receives an external factor as an input, estimates an optimum memory length in accordance with the input, and outputs a memory length control signal according to the result.
- the estimation method can take various forms depending on the application. As one of the forms, the average strength of the input signal is obtained, and based on the value, the memory length stored in advance is selected, and the memory length is selected. A method of outputting a long control signal is conceivable. If the memory length control circuit determines that decoding can be performed with the j-th stage memory length, the memory length control signal input to the storage circuit 13 after the j-th stage is generated by the OR circuit 72 so as to be all H. You.
- a memory length control signal may be generated with reference to the progress of Viterbi decoding.
- Figure 6 shows the circuit configuration in that case.
- Reference numeral 61 in FIG. 6 denotes a convergence determination circuit that observes the outputs of all the selective storage element circuits 12 for each stage and determines whether the result of Viterbi decoding has converged.
- the held data of all the states included in the same stage of the path memory circuit converge to the same value. Therefore, the output of each selected storage element circuit 12 is compared in each stage, and if all are equal, the memory length control signal supplied to the next stage is set to H.
- the memory length control signal of a stage is H
- the memory length control signal of that stage is also set to H by the OR circuit 62.
- the storage element circuit 11 of the memory area B in the second embodiment holds and outputs the input signal in synchronization with the clock signal when the memory length control signal power is ⁇ , and the memory length control signal is H In this case, an operation is performed to output the input signal as it is regardless of the clock signal. That is, in the first embodiment, the power required to separate the clock wiring between the memory area B and the memory area C is not necessary in the second embodiment. Further, the storage element circuit 11 having the same configuration as that of the memory area B can be used as the storage element circuit 11 of the memory area C.
- FIG. 7 shows a configuration diagram of such a storage element circuit 11.
- 31 is a synchronization pulse generation circuit
- 32 is a data holding circuit.
- the synchronization pulse generation circuit 31 outputs a pulse in synchronization with the rising edge of the synchronization signal when the (memory length) control signal is high, and outputs a fixed H signal when the control signal is high.
- the pulse width of the generated pulse signal is determined by the delay amount of the delay element in FIG.
- the data holding circuit 32 captures and outputs the input signal when the output signal of the synchronization pulse generation circuit 31 is H, and holds and outputs the captured data when the output signal is L.
- a clock signal and a memory length control signal supplied to the storage circuit 13 are input to the synchronization signal and the control signal in FIG. 7, respectively.
- the output signal of the selection circuit 10 is input as an input signal. Accordingly, in the memory circuit 13 of the memory length control signal strength, the storage element circuit 11 holds and outputs the output of the selection circuit 10 in synchronization with the clock signal, and the memory circuit 13 in which the memory length control signal is H Since the output signal of the synchronous pulse generation circuit 31 is fixed at H and the data holding circuit 32 is in a mode in which the input signal is fetched and output, the storage element circuit 11 outputs the output signal of the selection circuit 10 as it is. become.
- the clock signal supplied to the storage circuit 13 whose memory length control signal is H can be stopped. By doing so, the power consumed by the synchronization pulse generation circuit 31 and the buffer driving the clock signal, etc., can be reduced. Can be reduced.
- FIG. 8 is a further different configuration diagram of the storage element circuit 11 performing the same operation.
- 41 is a synchronization signal generation circuit
- 42 is a master storage circuit
- 43 is a slave storage circuit.
- the synchronization signal generation circuit 41 outputs the input synchronization signal as it is as the first and second synchronization signals CLK and CLK2, respectively.
- the control signal is H
- the same signal as the synchronization signal is output to CLK
- an inverted signal of the synchronization signal is output to CLK2.
- XCLK and XCLK2 output inverted signals of CLK and CLK2, respectively.
- the master memory circuit 42 captures and outputs the input signal when CLK is L, and retains the captured data when CLK is H
- the slave storage circuit 43 outputs while capturing the output of the master storage circuit 42 when CLK2 is H, and outputs while holding the captured data when CLK2 is L.
- a clock signal and a memory length control signal supplied to the storage circuit 13 are input to the synchronization signal and the control signal in FIG. 8, respectively.
- the output signal of the selection circuit 10 is input as a signal.
- the storage element circuit 11 holds and outputs the output of the selection circuit 10 in synchronization with the clock signal, while the memory circuit in which the memory length control signal is H is output.
- the output signals CLK and CLK2 of the synchronizing signal generation circuit 41 have inverted relationships.
- the storage element circuit 11 outputs the output signal of the selection circuit 10 as it is.
- Figure 9 shows the configuration diagram.
- Reference numeral 51 denotes a synchronization pulse generation circuit that generates a pulse signal synchronized with the clock signal
- 52 denotes a driver circuit that outputs a logical sum of an output of the synchronization pulse generation circuit 51 and a memory length control signal.
- the number of the synchronization pulse generation circuits 31 is equal to the number of the storage element circuits 11.
- a general latch is selected. It is used as a storage element circuit in the alternative storage element circuit 12, and a pulse signal to be supplied to them is generated by one synchronous pulse generation circuit 51, thereby reducing power and area.
- the pulse signal generated by the synchronous pulse generation circuit 51 is supplied to the selected storage element circuit 12 of each stage, and at that time, the force is also input by the logical sum of the corresponding memory length control signal by the driver circuit 52. Is done. As a result, an operation equivalent to that described above can be realized.
- FIG. 9 only the memory area B is shown. A similar configuration may be applied to the memory area C. At this time, the pulse signals supplied to the memory area B and the memory area C may be common.
- FIG. 10 shows a configuration diagram of the third embodiment.
- 14 is a repeater-type selection storage element circuit
- 15 is a synchronous-type selection storage element circuit
- 16 is a clock control circuit that controls a clock signal according to a memory length control signal.
- the repeater-type select storage element circuit 14 has the same structure as the above-described select storage element circuit 12, but the internal storage element circuit 11 retains the input signal as it is regardless of the clock signal when the memory length control signal is H. This is the storage element circuit to output.
- the synchronous selection storage element circuit 15 has the same structure as the selection storage element circuit 12 described above, but the internal storage element circuit 11 receives an input in synchronization with the clock signal when the memory length control signal is H. This is a storage element circuit that holds and outputs signals. However, in FIG. 10, the memory area A is not shown.
- part of the selected storage element circuit belonging to the memory area B is a synchronous selection storage element circuit 15 and the rest is a repeater selection storage element circuit 14.
- the synchronous selection storage circuit 15 is arranged every certain number of stages. The number of stages is determined by the period Tc of the clock signal input to the noise memory circuit and the output delay of the repeater type selective storage element circuit 14. The delay Td, the output delay To of the synchronous selection storage element circuit 15 and the setup constraint Ts, and the wiring delay T1 between the selection storage element circuits,
- the arrangement interval of the synchronous selection storage element circuit 15 can be determined as follows: ⁇ (Tc-Tl-To-Ts) / (Td + Tl).
- the clock control circuit 16 outputs a clock signal when the input memory length control signal is ⁇ , and stops the clock signal when the input is H.
- the output of the clock control circuit 16 is supplied to all the selected storage element circuits 14 and 12 in the memory area B and the memory area C in the stage where the repeater type selected storage element circuit 14 is used in the memory area B.
- the output of the clock control circuit 16 is supplied only to the selection storage element circuit 12 in the memory area C, and the selection storage element circuit in the memory area B (that is, the synchronous selection storage element circuit 15) is supplied. ) Receives the original clock signal not controlled by the clock control circuit 16.
- the synchronous selection storage element circuit 15 holds data in synchronization with the clock signal, Output, and the repeater type selection storage element circuit 14 outputs the input signal as it is.
- the selective storage element circuit 12 for any state may be used as the memory area B.
- the most efficient configuration is to perform the state transition to the same state.
- a group of the selective storage element circuits 12 relating to the state of the memory 12 is employed in the memory area B.
- state 0 (SO) and state 3 (S3) are suitable for the memory area B because there are state transitions in which the next states are S0 and S3, respectively.
- the selection circuit 10 can use the existing path without newly creating a special path for taking in the output of the previous selected storage element circuit 12 belonging to the memory area B. Can be used.
- state 1 (S1) in FIG. 2 is adopted as the memory area B
- the selected storage element relating to state 1 in the first stage The circuit 12 is not preferably connected to the selected storage element circuit 12 for the state 2 and the state 3 in the j-th stage, so that it is necessary to provide a new path for connecting to the selected storage element circuit 12 for the state 1, which is not preferable.
- the third embodiment the same applies to the third embodiment.
- FIG. 11 shows a configuration diagram of the memory area B according to the fourth embodiment.
- 17 is a scan path
- 18 is an operation mode control circuit.
- FIG. 11 does not show the memory area A and the memory area C.
- a data holding circuit such as a flip-flop includes a scan test circuit for chip inspection.
- FIG. 12 shows a data holding circuit with a scan function.
- 101 is a selection circuit that selects the normal input (D) when the mode selection signal (NT) is L, and selects the test input (SI) when it is H.
- 102 is synchronized with the clock signal (CK). This is a data holding circuit that holds and outputs input signals.
- Such a data holding circuit with a scan function is used for the storage element circuit 11 in the memory area B, and the scan path 17 is used to connect all the storage element circuits 11 in the memory area B to the i-th stage and the M-th stage. Configure to connect in ascending order. Further, the output signal of the operation mode control circuit 18 which outputs the input operation mode control signal when the memory length control signal is high and outputs the H fixed signal when the memory length control signal is high is stored in each stage. Input to NT of the selection circuit 101 in the element circuit 11.
- the storage element circuit 11 in the memory area B after the j-th stage operates in the scan mode. That is, the input of the storage element circuit 11 takes in the output of the storage element circuit 11 of the preceding stage input through the scan path 17 and repeats the output up to the storage element circuit 11 of the M-th stage.
- the selective storage element circuit 12 for any state is stored in the memory. Even in the memory area B, the efficiency of the circuit configuration does not change.
- the synchronous selection storage element circuit 15 and the repeater selection storage element circuit 14 can be mixed as shown in the third embodiment.
- the selected storage element circuit 12 relating to any state can be adopted as the memory area B.
- the memory area B Are arranged in one area each and are not included in each other, distribution of a memory length control signal, an operation mode control signal, a clock signal, and the like becomes easy.
- the path memory circuit according to the present invention has a feature of realizing a function of changing the memory length while suppressing an increase in circuit scale, and is useful as an error correction technique in a read channel system of a communication, optical disk, or magnetic disk. It is.
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- Error Detection And Correction (AREA)
- Detection And Correction Of Errors (AREA)
Abstract
Description
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2006512247A JP4324195B2 (ja) | 2004-04-07 | 2004-12-07 | パスメモリ回路 |
US10/593,280 US7734992B2 (en) | 2004-04-07 | 2004-12-07 | Path memory circuit |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2004112786 | 2004-04-07 | ||
JP2004-112786 | 2004-04-07 |
Publications (1)
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WO2005101669A1 true WO2005101669A1 (ja) | 2005-10-27 |
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PCT/JP2004/018194 WO2005101669A1 (ja) | 2004-04-07 | 2004-12-07 | パスメモリ回路 |
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US (1) | US7734992B2 (ja) |
JP (1) | JP4324195B2 (ja) |
WO (1) | WO2005101669A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009044389A (ja) * | 2007-08-08 | 2009-02-26 | Rohm Co Ltd | 無線通信システムおよび送信端末 |
JP2009044381A (ja) * | 2007-08-08 | 2009-02-26 | Rohm Co Ltd | 無線通信システム、送信端末、および、受信端末 |
US8223856B2 (en) | 2007-08-08 | 2012-07-17 | Rohm Co., Ltd. | Radio communication system carrying out transmission and reception of multicarrier signal, transmission terminal, and reception terminal |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5521926B2 (ja) * | 2010-09-13 | 2014-06-18 | 富士通株式会社 | 記憶システム、制御装置、および記憶装置 |
JPWO2015177917A1 (ja) * | 2014-05-23 | 2017-04-20 | 富士通株式会社 | 演算回路、符号化回路及び復号回路 |
Citations (3)
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JPS6175935A (ja) * | 1984-09-21 | 1986-04-18 | Fujitsu Ltd | スキヤンフリツプ・フロツプ方式 |
JP2001144633A (ja) * | 1999-11-16 | 2001-05-25 | Hitachi Ltd | ビタビ検出器、信号処理回路、記録再生装置および情報処理システム |
JP2002368628A (ja) * | 2001-06-11 | 2002-12-20 | Nec Corp | ビタビ復号器 |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH0659049B2 (ja) | 1986-12-27 | 1994-08-03 | 日本電気株式会社 | デ−タ受信機 |
US5432820A (en) * | 1990-11-19 | 1995-07-11 | Fujitsu Limited | Maximum-likelihood decoding method and device |
KR930004862B1 (ko) * | 1990-12-17 | 1993-06-09 | 삼성전자 주식회사 | 상태 평가량 기억장치 |
JPH10107651A (ja) * | 1996-09-27 | 1998-04-24 | Nec Corp | ビタビ復号装置 |
JPH10302412A (ja) | 1997-04-30 | 1998-11-13 | Sony Corp | 情報再生装置および再生方法 |
JP3747604B2 (ja) * | 1997-12-19 | 2006-02-22 | ソニー株式会社 | ビタビ復号装置 |
JP3250550B2 (ja) * | 1999-09-02 | 2002-01-28 | 日本電気株式会社 | パスメモリ回路およびビタビ復号回路 |
-
2004
- 2004-12-07 WO PCT/JP2004/018194 patent/WO2005101669A1/ja active Application Filing
- 2004-12-07 US US10/593,280 patent/US7734992B2/en not_active Expired - Fee Related
- 2004-12-07 JP JP2006512247A patent/JP4324195B2/ja not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS6175935A (ja) * | 1984-09-21 | 1986-04-18 | Fujitsu Ltd | スキヤンフリツプ・フロツプ方式 |
JP2001144633A (ja) * | 1999-11-16 | 2001-05-25 | Hitachi Ltd | ビタビ検出器、信号処理回路、記録再生装置および情報処理システム |
JP2002368628A (ja) * | 2001-06-11 | 2002-12-20 | Nec Corp | ビタビ復号器 |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009044389A (ja) * | 2007-08-08 | 2009-02-26 | Rohm Co Ltd | 無線通信システムおよび送信端末 |
JP2009044381A (ja) * | 2007-08-08 | 2009-02-26 | Rohm Co Ltd | 無線通信システム、送信端末、および、受信端末 |
US8223856B2 (en) | 2007-08-08 | 2012-07-17 | Rohm Co., Ltd. | Radio communication system carrying out transmission and reception of multicarrier signal, transmission terminal, and reception terminal |
Also Published As
Publication number | Publication date |
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US7734992B2 (en) | 2010-06-08 |
US20070177687A1 (en) | 2007-08-02 |
JPWO2005101669A1 (ja) | 2007-08-16 |
JP4324195B2 (ja) | 2009-09-02 |
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