WO2001069808A1 - Recepteur et procede de reception pour communication a spectre etale - Google Patents
Recepteur et procede de reception pour communication a spectre etale Download PDFInfo
- Publication number
- WO2001069808A1 WO2001069808A1 PCT/JP2001/001945 JP0101945W WO0169808A1 WO 2001069808 A1 WO2001069808 A1 WO 2001069808A1 JP 0101945 W JP0101945 W JP 0101945W WO 0169808 A1 WO0169808 A1 WO 0169808A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- data signal
- signal
- equalizer
- spread spectrum
- distortion
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/7103—Interference-related aspects the interference being multiple access interference
- H04B1/7105—Joint detection techniques, e.g. linear detectors
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
- H04B1/711—Interference-related aspects the interference being multi-path interference
- H04B1/7115—Constructive combining of multi-path signals, i.e. RAKE receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/005—Control of transmission; Equalising
-
- 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
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03114—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals
- H04L25/03146—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals with a recursive structure
-
- 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
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
- H04L2025/03375—Passband transmission
-
- 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
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/03433—Arrangements for removing intersymbol interference characterised by equaliser structure
- H04L2025/03439—Fixed structures
- H04L2025/03445—Time domain
- H04L2025/03471—Tapped delay lines
- H04L2025/03484—Tapped delay lines time-recursive
Definitions
- the present invention relates to a radio receiver and a radio reception method based on a communication system using a spread spectrum system.
- the spread spectrum system is a communication system that performs modulation for spreading a frequency spectrum of a signal over a wide band, and has advantages such as drought resistance, confidentiality of communication, and communication that can share the same frequency band. For this reason, in recent years, it is widely used for land mobile communication such as mobile phones and communication channels such as mobile satellite communication.
- CDMA Code Division Multiple Access
- CDMA Code Division Multiple Access
- the relative value of the signal arrival time can be accurately calculated by using a signal generated by the spread spectrum modulation signal. For this reason, it is also used in the Global Positioning System (GPS), which can accurately measure the current position of a moving object.
- GPS Global Positioning System
- the received signal and The original signal is restored (demodulated) by calculating the correlation with a known code in advance.
- FIGS. 4A and B show examples of received signal waveforms.
- the horizontal axis represents time t, and the vertical axis represents the strength of correlation at the time of reception.
- the unit of time is the chip time, which represents the speed of the spread code.
- the spreading factor S F is several to several ten or more, and the greater the spreading factor, the stronger the interference and noise.
- a correlation peak appears, and when the time is shifted even one chip time (+1 or In 1), the correlation peak is lost. If there are multiple paths from signal sources such as satellites and mobile phone base stations, and if the time difference of signal propagation in each path exceeds one chip time, the number of correlation peaks is detected.
- the correlation is detected as one peak in chip time units.
- the waveform shown in FIG. 4B is a case where signals coming from two different paths are received with the same phase, and are mutually strengthened to form a waveform as shown in the figure. However, if they are received in opposite phases, they cancel each other out and the peak value becomes smaller.
- the number of routes is 3 or more, or when a continuous distribution is shown, the shape differs from the waveform shown in the figure. In this way, waves that have a mutually reinforcing relationship at one moment cancel each other out at the next moment, and the phenomenon that the reception level fluctuates is called fading.
- There are various models such as aging.
- the signal strength generally has a valley of -10 dB or more, depending on the fusing cycle.
- a rake receiver As a receiving method for improving the characteristics of the spread spectrum communication method with respect to multipath fading as described above, a rake receiver is conventionally known. This is achieved by separating the delayed waves separated by more than one chip time as separate paths, despreading and demodulating the received waves of each path, demodulating the signals, and combining them in consideration of each delay time. This is to improve the ratio.
- the only fading countermeasure was to multiply the received wave by a code, so it was difficult to separate multipaths with a signal propagation time difference of less than one chip time. Therefore, even with the RAKE receiver, it was not possible to cope with the deterioration of receiving performance due to fading caused by multipath with a delay time within one chip time.
- Japanese Patent Application Laid-Open The publication No. 172419 discloses that, in a transmitting means, a real part and an imaginary part of a complex number are spread-modulated as a product of complex numbers using a complex spreading code which is uncorrelated and random. Disclosure discloses a method in which a fractional interval equalizer and a complex type RLS (sequential least squares) adaptive algorithm are used to demodulate transmission data to remove fading due to intersymbol interference. Have been.
- Japanese Patent Application Laid-Open No. H11-41157 discloses a receiving apparatus in which a plurality of directional antennas having different directivities are used to obtain a path diversity effect.
- the present invention has been made in view of the above-described conventional problem, and has been made in consideration of a radio reception in a spread spectrum communication system capable of preventing fading deterioration due to a multipath having a delay time difference within one chip time. It is an object to provide a wireless communication device and a wireless reception method.
- the present invention relates to a radio receiver using a spread spectrum communication method, which estimates a transmission channel model, and uses a transmission function of a transmission channel obtained as a result of the estimation to transmit data.
- An object of the present invention is to provide a wireless receiver including an equalizer that performs signal distortion correction.
- the equalizer is configured by an adaptive filter based on an IIR filter, Preferably, it is located before the demodulator of the radio receiver.
- the equalizer estimates a transmission channel model using a known signal broadcast together with the data signal, and expresses an inverse function of a transfer function obtained as a result of the estimation in the IIR filter. Is preferred.
- the equalizer corrects distortion due to a delayed wave within one chip time by oversampling the received data signal.
- the known signal is any one of a pilot symbol, a pilot channel, and a preamble broadcasted together with a data signal.
- the wireless receiver is provided with Furthermore, the present invention relates to a radio reception method using a spread spectrum communication method, which estimates a transmission channel model and corrects a distortion of a received data signal using a transfer function of the transmission channel obtained as a result of the estimation. It provides a receiving method.
- the distortion correction of the received data signal is preferably performed before demodulating the data signal.
- the model estimation of the transmission path is performed by using a known signal broadcast together with the data signal.
- the known signal is any one of a pilot symbol, a pilot channel, and a preamble broadcast together with a data signal.
- the present invention relates to a radio reception method based on a spread spectrum communication system, wherein a transfer function of a transmission path is calculated based on a known signal broadcasted together with a data signal.
- the transfer function is used to correct the distortion of the received data signal due to a delayed wave within one chip time, and demodulate a plurality of signals that have been corrected for distortion and separated by one chip time or more, and combine them.
- a radio receiving method for outputting the data BRIEF DESCRIPTION OF THE FIGURES
- FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a radio receiver using a spread spectrum communication system according to the present invention.
- FIG. 2 is a block diagram illustrating a schematic configuration of an equalizer that performs adaptive processing according to the present embodiment.
- FIG. 3 is a block diagram showing a schematic configuration of an IR filter used in the equalizer according to the present embodiment.
- FIG. 4A is an explanatory diagram showing a waveform of a received signal
- FIG. 4B is an explanatory diagram showing fading caused by a delayed wave within one chip time.
- a wireless receiver and a wireless receiving method based on a spread spectrum communication method according to the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.
- the radio receiver is a radio receiver based on a communication system using spread spectrum, and an equalizer (equalizer) using an adaptive filter based on an IIR filter is used as a radio receiver. It is placed between the input end and a demodulator that performs spread spectrum demodulation. For example, it operates between the low-pass filter (LPF) in the baseband part of the receiver and the correlator in the CDMA demodulator with a clock N times the chip frequency. Put the equalizer to make.
- LPF low-pass filter
- FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a radio receiver using a spread spectrum communication system according to the present invention.
- a radio receiver 10 according to the present embodiment is configured by arranging an equalizer 14 between an input terminal and a demodulator 12 for performing spread spectrum demodulation.
- the demodulator 12 is a rake demodulator comprising a plurality of finger circuits 16 and a maximum ratio combining circuit 18 for maximum ratio combining of the signals demodulated by the finger circuits 16.
- An equalizer 14 is arranged before each finger circuit 16.
- One equalizer 14 and one finger circuit 16 correspond to the received wave having a delay difference within one chip, and as shown in Fig. 1, the equalizer 14 and the finger circuit 16 The reason why a plurality of pairs are arranged is to demodulate received waves separated by one chip or more.
- the equalizer 14 performs adaptive equalization processing on the delayed wave within one chip time, extracts the original signal, and further demodulates the extracted signal with the finger circuit 16.
- the maximum ratio combining circuit 18 demodulates the signal separated by one chip time or more by the finger circuit 16, weights the received power (power) representing the magnitude of the signal, and outputs the sum. That is, a plurality of peaks are collected into one, and the dispersed powers are combined to increase the SN ratio.
- the equalizer is a filter that corrects the distortion of the input signal and reproduces the original signal, and is important as a measure against interference caused by multipath fading. Extract original signal by equalizer If they can be released, their resistance to fading can be increased.
- FIG. 2 shows a schematic configuration of the equalizer 14 that performs adaptive processing according to the present embodiment.
- the equalizer 14 of the present embodiment is based on the IIR filter, and includes a selector 20, a code generator 22, an FIR filter 24, an error evaluation circuit 26, a coefficient setting circuit 28, and an IIR filter 30. It is composed of
- the IR filter 30 constituting the main part of the equalizer 14 has N taps and operates with a clock that is N times the chip frequency.
- the IIR filter 30 attempts to extract a delayed wave within one chip time by oversampling the input signal N times in this way.
- FIG. 3 shows a schematic configuration of an example of the IR filter 30.
- the IIR filter 30 of the present embodiment includes adders 32 and 34, N delay elements (flip-flops) 36, a multiplier 38, and a coefficient holding circuit 40, respectively.
- the input signal S i of the equalizer 14 has already been digitized.
- the input is a real number in the case of BP SK (Binary Phase Shift Keying), and a complex number in the case of QP SK (Quadrature Phase Shift Keying).
- BP SK Binary Phase Shift Keying
- QP SK Quadrature Phase Shift Keying
- the delay operator is D, al, ⁇ , where ⁇ is a coefficient having an absolute value of 1 or less (a complex number in the case of QPSK), and the oversampling rate.
- N N
- the following equation (1) holds to have a delay of one chip time or less.
- the equalizer 14 may perform the operation represented by the following expression (2) in order to compensate for the delay within one chip time and restore the original signal.
- a known signal such as a preamble, a pilot channel, and a pilot symbol is usually broadcast.
- a pilot symbol transmitted in a time-division manner with data is used as a known signal used for adaptation.
- the equalizer 14 of the present embodiment generates a known pilot symbol sequence in accordance with the received pilot symbol sequence, and also performs spreading based on a previously known spreading code. .
- the known pilot symbol is multiplied by the spread code generated by the code generator 22 and input to the FIR filter 24.
- FIR filter 24 performs adaptive equalization as a model transmission path, and its output and actual input signal Is compared with the error evaluation circuit 26 in the next stage to estimate the model transmission path.
- the output of the FIR filter 24 is compared with the received pilot symbol string separated from the input received signal by the selector 20. Then, a difference per pilot symbol or a plurality of pilot symbols is calculated as an error.
- This calculation result is input to the coefficient setting circuit 28.
- coefficients 1, 1,..., ⁇ of the FIR filter 24 are set so that the error approaches zero.
- the coefficients ⁇ 1,..., ⁇ are fed back to the FIR filter 24. This is repeated, and the coefficient is sequentially changed so that the error approaches zero.
- methods such as successive approximation and RLMS (sequential least squares method) are effective.
- the error approaches 0 it means that the transmission channel model represented by the coefficients al,..., ⁇ in the equation (1) has been obtained.
- the coefficients 1, 1,..., ⁇ are multiplied by (1-1) and transferred to the IR filter 30.
- the inverse function is obtained, and the IIR filter 30 extracts the corresponding signal from the received signal output from the selector 20 using the coefficients 1, 1, Output to container 12.
- data demodulation in which the transmission path is estimated using pilot symbols is obtained.
- the input data is sequentially sent by the delay element 36, and is multiplied by the coefficient ci stored in each coefficient holding circuit 40 by the multiplier 38.
- Each multiplied data is added by an adder 34, fed back, and added to new data by an adder 32 and output.
- the delayed waves in one chip are combined into one and output to the finger circuit 16 of the demodulator 12.
- the finger circuit 16 demodulates this signal and outputs it to the maximum ratio combining circuit 18.
- the maximum ratio combining circuit 18 combines the signals sent from the finger circuits 16 by weighting them according to their power. As a result, in the present embodiment, it is possible to prevent the fogging from being deteriorated due to the multipath having only a delay within one chip time.
- the strongest path may not be the first to arrive as a result of interference. In that case, only the coefficient of the place corresponding to the large path in the coefficient sequence ⁇ i ⁇ of the transmission path model becomes larger than 1, and the generality of the model is not lost.
- the number of samples in one chip time is increased.
- an adaptive filter that operates at the sampling rate, it is possible to prevent deterioration of communication quality due to fading due to intra-chip multipath that could not be removed conventionally.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Power Engineering (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Noise Elimination (AREA)
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP01912297A EP1176733A4 (en) | 2000-03-13 | 2001-03-13 | RECEIVER AND RECEPTION METHOD FOR SPREAD SPECTRUM COMMUNICATION |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000068962A JP2001257627A (ja) | 2000-03-13 | 2000-03-13 | 無線受信機 |
JP2000-68962 | 2000-03-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001069808A1 true WO2001069808A1 (fr) | 2001-09-20 |
Family
ID=18587933
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2001/001945 WO2001069808A1 (fr) | 2000-03-13 | 2001-03-13 | Recepteur et procede de reception pour communication a spectre etale |
Country Status (4)
Country | Link |
---|---|
US (1) | US20020159505A1 (ja) |
EP (1) | EP1176733A4 (ja) |
JP (1) | JP2001257627A (ja) |
WO (1) | WO2001069808A1 (ja) |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1271871A1 (en) * | 2001-06-20 | 2003-01-02 | Motorola, Inc. | Compensation of mismatch between quadrature paths |
JP2003224496A (ja) * | 2002-01-29 | 2003-08-08 | Matsushita Electric Ind Co Ltd | 送受信装置、無線通信システム及び送受信方法 |
US6987797B2 (en) | 2002-07-26 | 2006-01-17 | Qualcomm Incorporated | Non-parametric matched filter receiver for wireless communication systems |
US7272176B2 (en) * | 2003-02-18 | 2007-09-18 | Qualcomm Incorporated | Communication receiver with an adaptive equalizer |
US7257377B2 (en) | 2003-02-18 | 2007-08-14 | Qualcomm, Incorporated | Systems and methods for improving channel estimation |
US7236549B2 (en) * | 2003-07-03 | 2007-06-26 | Freesystems Pte. Ltd | Digital switching wireless receiver diversity and buffer diversity for enhanced reception in a wireless digital audio communication system |
EP1551109B1 (fr) * | 2004-01-05 | 2009-11-25 | STMicroelectronics N.V. | Procédé d'élimination des faux échos dans un récepteur Rake |
JP4523968B2 (ja) * | 2005-03-25 | 2010-08-11 | パイオニア株式会社 | 無線受信機 |
EP1924004B1 (en) * | 2005-09-06 | 2015-04-08 | Fujitsu Ltd. | Equalizer device and method |
US7936810B2 (en) * | 2005-09-08 | 2011-05-03 | Texas Instruments Incorporated | Delayed combining of frequency-domain equalized wireless channels with large delay-spreads |
CN101454993A (zh) * | 2006-09-29 | 2009-06-10 | 松下电器产业株式会社 | 波形均衡装置 |
JP5692435B1 (ja) * | 2014-02-27 | 2015-04-01 | 日本電気株式会社 | 無線通信システム、無線通信装置および無線通信方法 |
DE102017116273A1 (de) * | 2017-03-30 | 2018-10-04 | Riedel Communications International GmbH | Netzwerkgerät für ein Intercom-Netzwerk |
WO2021095127A1 (ja) * | 2019-11-12 | 2021-05-20 | 日本電信電話株式会社 | 受信装置 |
Citations (4)
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JPH0974372A (ja) * | 1995-09-04 | 1997-03-18 | Matsushita Electric Ind Co Ltd | スペクトラム拡散無線伝送受信装置 |
JPH10200503A (ja) * | 1997-01-09 | 1998-07-31 | Matsushita Electric Ind Co Ltd | スペクトル拡散通信用適応等化回路 |
JPH11266232A (ja) * | 1997-12-30 | 1999-09-28 | Motorola Inc | 拡散スペクトル通信システムにおいて適応等化を用いて干渉抑制を行うための通信装置および方法 |
JP2000138656A (ja) * | 1998-11-04 | 2000-05-16 | Nec Corp | 移動局受信方法ならびに移動局受信装置 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2721466B1 (fr) * | 1994-06-21 | 1996-07-26 | Alcatel Mobile Comm France | Signal de contrôle pour récepteurs, dispositif de synchronisation, dispositif d'égalisation, procédé de synchronisation et récepteurs correspondants. |
US6483821B1 (en) * | 1998-04-22 | 2002-11-19 | Texas Instruments Incorporated | CDMA mobile communications system and method with improved channel estimation and pilot symbol transmission |
US6643275B1 (en) * | 1998-05-15 | 2003-11-04 | Telefonaktiebolaget Lm Ericsson (Publ) | Random access in a mobile telecommunications system |
GB9818378D0 (en) * | 1998-08-21 | 1998-10-21 | Nokia Mobile Phones Ltd | Receiver |
DE69803574T2 (de) * | 1998-10-27 | 2002-08-29 | Bosch Gmbh Robert | Verfahren zur Schätzung der Kanalimpulsantwort eines Signalübertragungskanals und Mobilstation |
US6304299B1 (en) * | 1998-11-30 | 2001-10-16 | General Electric Company | System and method for mitigating multipath effects in television systems |
US6658047B1 (en) * | 1999-03-10 | 2003-12-02 | Nokia Corporation | Adaptive channel equalizer |
US6674815B2 (en) * | 1999-06-16 | 2004-01-06 | Ericsson, Inc | Method for symbol-spaced estimation and/or tracking of a fractionally-spaced fading radio channel |
-
2000
- 2000-03-13 JP JP2000068962A patent/JP2001257627A/ja not_active Withdrawn
-
2001
- 2001-03-13 WO PCT/JP2001/001945 patent/WO2001069808A1/ja not_active Application Discontinuation
- 2001-03-13 US US09/959,831 patent/US20020159505A1/en not_active Abandoned
- 2001-03-13 EP EP01912297A patent/EP1176733A4/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH0974372A (ja) * | 1995-09-04 | 1997-03-18 | Matsushita Electric Ind Co Ltd | スペクトラム拡散無線伝送受信装置 |
JPH10200503A (ja) * | 1997-01-09 | 1998-07-31 | Matsushita Electric Ind Co Ltd | スペクトル拡散通信用適応等化回路 |
JPH11266232A (ja) * | 1997-12-30 | 1999-09-28 | Motorola Inc | 拡散スペクトル通信システムにおいて適応等化を用いて干渉抑制を行うための通信装置および方法 |
JP2000138656A (ja) * | 1998-11-04 | 2000-05-16 | Nec Corp | 移動局受信方法ならびに移動局受信装置 |
Non-Patent Citations (1)
Title |
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See also references of EP1176733A4 * |
Also Published As
Publication number | Publication date |
---|---|
EP1176733A1 (en) | 2002-01-30 |
EP1176733A4 (en) | 2005-07-20 |
JP2001257627A (ja) | 2001-09-21 |
US20020159505A1 (en) | 2002-10-31 |
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