EP3130122A1 - Dispositif pour estimer un décalage de fréquence dans un multiplexage par répartition orthogonale de la fréquence (ofdm) et procédé correspondant - Google Patents

Dispositif pour estimer un décalage de fréquence dans un multiplexage par répartition orthogonale de la fréquence (ofdm) et procédé correspondant

Info

Publication number
EP3130122A1
EP3130122A1 EP14716796.9A EP14716796A EP3130122A1 EP 3130122 A1 EP3130122 A1 EP 3130122A1 EP 14716796 A EP14716796 A EP 14716796A EP 3130122 A1 EP3130122 A1 EP 3130122A1
Authority
EP
European Patent Office
Prior art keywords
frequency
frequency offset
offset estimation
received signal
ofdm symbol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14716796.9A
Other languages
German (de)
English (en)
Inventor
Basuki Endah Priyanto
Fredrik RUSEK
Gengshi Wu
Sha HU
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Huawei Technologies Co Ltd
Original Assignee
Huawei Technologies Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huawei Technologies Co Ltd filed Critical Huawei Technologies Co Ltd
Publication of EP3130122A1 publication Critical patent/EP3130122A1/fr
Withdrawn legal-status Critical Current

Links

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
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H04L27/266—Fine or fractional frequency offset determination and synchronisation
    • 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
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2669—Details of algorithms characterised by the domain of operation
    • H04L27/2672—Frequency domain
    • 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
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2681—Details of algorithms characterised by constraints
    • H04L27/2686—Range of frequencies or delays tested
    • 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
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation

Definitions

  • the present invention relates to a device for estimating frequency offset of a received multi carrier signal. Furthermore, the present invention also relates to a corresponding method, a communication device comprising such a estimation device, a computer program, and a computer program product.
  • Orthogonal Frequency Division Multiplexing has been widely used in the recent wireless communication standards, including 4G Long Term Evolution (LTE), Wi-Fi, and Worldwide Interoperability for Microwave Access (WiMax).
  • LTE Long Term Evolution
  • Wi-Fi Worldwide Interoperability for Microwave Access
  • the OFDM technique enables high speed wireless data transmission by allowing spectrum overlap of multi-carrier transmissions and thus increases the spectral efficiency.
  • the OFDM transmission systems become more sensitive to frequency offset than conventional single carrier transmission systems.
  • OFDM requires the transmitted signal to be sampled at the centre frequency of each sub-carrier as shown in Fig. 1 .
  • a frequency offset introduces signal degradation, phase rotation and Inter-Carrier Interference (ICI) which will lead to performance degradation. Therefore, frequency offset estimation and correction of frequency offset play an important role in an OFDM based receiver.
  • ICI Inter-Carrier Interference
  • Frequency offset is known as a frequency drift between the carrier frequency of transmitter and receiver and is commonly known as Carrier Frequency Offset (CFO) £ CF0 .
  • LTE has a frequency spacing of 15 kHz.
  • the IFO can be ⁇ ⁇ 15 kHz, where N is an integer.
  • FFO is limited within ⁇ 7.5 kHz or ⁇ 0.5 in normalized frequency offset.
  • the process is typically divided into two steps, namely acquisition stage and tracking stage.
  • the acquisition stage is targeting to estimate coarse frequency error and it is usually performed in every radio frame (e.g., 10 ms duration).
  • the tracking stage is designed to estimate fine frequency offset and is performed more frequently which can be every sub-frame e.g., 1 ms duration in LTE.
  • the antenna 1 1 receives a transmitted signal and processes the received signal by amplifying the signal in the radio front-end and down converting the carrier frequency to a baseband signal.
  • the digital baseband unit thereafter performs many operations including the frequency offset estimation described above.
  • the frequency offset estimation output 12 is then used to adjust the receiver's local oscillator carrier frequency.
  • a low cost crystal oscillator at the receiver can introduce large frequency deviations, especially if there is a temperature change in the receiver.
  • DRX Discontinuous Reception
  • LTE where the radio front-end is frequently switched on and off can also introduce a large frequency offset which reduces the receiver performance.
  • LTE UEs are designed to estimate and correct the frequency error to mitigate the effects of the same.
  • Frequency offset estimation can be performed in the time domain or in the frequency domain.
  • the time domain solution typically utilizes: the received dedicated training symbols/preamble sent by transmitter (e.g., a base station or an access point) to assist synchronization; and the received cyclic prefix part (or also known as guard interval) of the OFDM signal.
  • the time domain operation is performed by utilizing the signal characteristics of the received signal.
  • Cyclic Prefix (CP) is essentially a copy of the last few samples of an OFDM symbol and placed in the beginning of the OFDM symbol.
  • ML Maximum Likelihood
  • Time domain frequency offset estimation typically has quite wide frequency offset estimation range. According to prior art the normalized frequency offset estimation £ FOE can be estimated within
  • Time domain frequency offset estimation using either dedicated training symbols or cyclic prefix has however several practical problems, including sensitive to residual Direct Current (DC) offset, spurs signal, and narrow band interference. The presence of those imperfections can destroy the correlation output.
  • DC Direct Current
  • frequency domain solutions for frequency offset estimation typically use received pilot symbol at certain positions of the transmitted signal. The principle operation also relies on the correlation operation of the transmitted signal. The frequency offset captured range is also determined by the placement of the pilot symbols in the time domain.
  • Frequency domain frequency offset estimation has a fundamental issue that the frequency offset range is limited to the pilot structure of the received signal. According to some conventional methods the pilot symbols are restricted to be placed in two adjacent OFDM symbols. This will enable the frequency offset capture range within
  • FFO Fractional Frequency Offset
  • CRSs Common Reference Symbols
  • the phase rotation measured by the correlation of CRS in two OFDM symbols can be used to estimate the frequency offset.
  • the problem in LTE systems is that the reference symbol/pilot is not located at the same sub-carrier for two consecutive OFDM symbols.
  • the absolute maximum ran e for the normalized & FOE is,
  • the CRS in LTE with normal CP configuration are located in OFDM symbol numbers 0, 4, 7, and 1 1 , respectively.
  • the smallest distance between OFDM symbols of the CRS from the same antenna port, i.e., symbol 4 and 7 ( ⁇ 3).
  • the frequency offset capture range of the baseline method is limited maximum up tols ⁇ J ⁇ 0.1553 , which is smaller than FF0 .
  • Another conventional solution can capture wider range within around
  • This method requires several numbers of correlations between OFDM symbols, including across sub-frame.
  • Look-Up Table (LUT) implementation is required. Thus, the result is heavily affected by the accuracy of the LUT implementation.
  • An objective of the present invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions for frequency offset estimation.
  • Another objective of the present invention is to provide improved frequency offset estimations of received signals, such as multicarrier signals.
  • the above mentioned and other objectives are achieved with a device for estimating frequency offset of a received (multi carrier) signal, for example, in a wireless communication system.
  • the device is adapted to: receive the signal comprising at least one Orthogonal Frequency Division Multiplexing, OFDM, symbol pair transmitted over a radio channel;
  • OFDM Orthogonal Frequency Division Multiplexing
  • a communication device adapted for communication in a wireless communication system, and comprising at least one device for estimating frequency offset according to embodiments of the present invention.
  • a method for estimating a frequency offset of a received (multi carrier) signal for example in a wireless communication system, the method comprising the steps of:
  • OFDM Orthogonal Frequency Division Multiplexing
  • An OFDM symbol pair is two OFDM symbols carrying pilot symbols wherein the distance between the OFDM symbols in a pair will reflect the frequency offset estimation range.
  • Frequency capture range is the range within which the frequency offset can be estimated and corrected by a receiver.
  • Embodiments of the present invention provide an estimation solution with a flexible frequency offset capture range which e.g., can cover the entire range of fractional frequency offset z FFO or even more of an LTE system. Further, since the frequency estimation is performed in the frequency domain the present solution is robust against impairments, such as DC offset and narrow band interference. Moreover, the maximum complexity is expected to be approximately increased linearly with the multiplication factor of the range extension from the baseline frequency offset estimator which is an advantage. The proposed solution further offers the design option of trade-off between complexity and performance. Hence, the performance can be improved by utilizing more data/input whenever it is available.
  • the device is further adapted to use a Finite Impulse Response, FIR, filter for frequency shifting said received signal so as to extend the frequency capture range.
  • FIR Finite Impulse Response
  • the FIR filter may have the filter coefficients C(m) calculable by
  • N FFT is a number of Fast
  • N gi is a length of guard interval or cyclic prefix of said received signal, and / is an OFDM symbol index within one sub-frame of said received signal.
  • the device is further adapted to frequency shift said received signal N times so as to obtain N + 1 frequency offset estimations e k , ⁇ k e l,2,..., N+ l ⁇ extending the frequency capture range by N + 1 times a frequency capture range of an individual frequency offset estimation £ k so as to obtain adjacent frequency estimation regions.
  • N + 1 frequency offset estimations are obtained since every frequency shift results in one frequency offset estimation each and additionally one frequency offset estimation is obtained without frequency shifting, i.e. for the region around the carrier frequency.
  • This embodiment means that the total capture range will be maximal in relation to the number of frequency shifts as there is no overlap.
  • the device is further adapted to frequency shift said received signal N times so as to obtain N + 1 frequency offset estimations e k , ⁇ k e l,2,..., N+ l ⁇ extending the frequency capture range by less than N + 1 times a frequency capture range of an individual frequency offset estimation £ k so as to obtain overlapping frequency estimation regions.
  • the complexity may be higher compared to the non-overlapping case but the performance is improved with overlapping ranges.
  • frequency offset estimations are pair-wise symmetrically arranged around a transmit carrier frequency for said received signal according to another embodiment. This means optimal frequency capture ranges are achieved and also that the implementation of such an embodiment of the present invention is simplified.
  • the present device is further adapted to obtain the N + 1 frequency offset estimations e k , ⁇ k e l,2,..., N+ l ⁇ by correlating channel estimates determined from pilot symbols of the at least one OFDM symbol pair.
  • the device may further be adapted to use a reduced number of sub-carriers of the at least one OFDM symbol pair for correlating channel estimates. This embodiment reduces computational load.
  • the present device may further be adapted to use one OFDM symbol pair per each frequency offset estimation e k , ⁇ k e l,2,..., N+ l ⁇ for correlating channel estimates, the OFDM symbol pairs used for each frequency offset estimation e k , ⁇ k e l,2,..., N+ l ⁇ being the same OFDM symbol pair or having the same symbol distance. Therefore, since all frequency estimators will have the same offset capture range the final offset is easier obtained since the offset candidates are easily compared, e.g. by comparing correlation values.
  • the device may yet further be adapted to use additional OFDM symbol pairs for correlating channel estimates for a frequency offset estimation £ k associated with a transmit carrier frequency for said received signal.
  • the device is further adapted to select a frequency offset estimation £ k having a highest absolute correlation value from the OFDM symbol pair as said frequency offset estimation & FOE . This embodiment results in very low complexity in the selection process.
  • the device is further adapted to use at least one Maximum Likelihood, ML, function for selecting said frequency offset estimation £ FOE .
  • ML Maximum Likelihood
  • two OFDM symbol pairs may be used for frequency offset estimation, and the device is further adapted to compute a minimum distance for two sets of frequency estimations, and to select a frequency offset ⁇ , + ⁇ 2
  • the radio channel is a Multiple Input Multiple Output, MIMO, channel
  • the device is further adapted to compute correlation values of channel estimates for the at least one OFDM symbol pair for each MIMO stream; linearly combine the computed correlation values for each MIMO stream; and using the combined correlation values for estimating said frequency offset £ FOE .
  • the present invention also relates to a computer program, characterized in code means, which when run by processing means causes said processing means to execute any method according to the present invention.
  • the invention also relates to a computer program product comprising a computer readable medium and said mentioned computer program, wherein said computer program is included in the computer readable medium, and comprises of one or more from the group: ROM (Read-Only Memory), PROM (Programmable ROM), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically EPROM) and hard disk drive.
  • - Fig. 1 illustrates sub-carriers representation of OFDM signal and frequency offset in LTE
  • - Fig. 2 illustrates frequency offset estimation and frequency offset estimation correction in a prior art receiver
  • - Fig. 3 illustrates linear interpolation operations of least square channel estimates for sub-carrier without pilots and correlation between OFDM symbols carrying pilots
  • - Fig. 4 illustrates a block diagram of a frequency offset estimator with frequency shift
  • FIG. 6 illustrates a receiver structure according to an embodiment of the present invention
  • - Fig. 7 illustrates non-overlapping N frequency shifts (4 re-sampling filters which gives 5 zones);
  • - Fig. 8 illustrates receiver block diagram for estimating frequency offset according to an embodiment of the present invention
  • - Fig. 9 illustrates how multiple antennas generate more data samples in a MIMO scenario
  • Fig. 10 shows a flow chart for frequency offset estimation with different frequency offset ranges according to an embodiment of the present invention
  • - Fig. 1 1 illustrates performance evaluation for various schemes with frequency offset ⁇ 7 kHz;
  • - Fig. 12 illustrates performance evaluation for various schemes with frequency offset ⁇ 10 kHz;
  • FIG. 13 illustrates a method according to an embodiment of the present invention
  • FIG. 14 illustrates an estimation device according to an embodiment of the present invention.
  • FIG. 15 schematically illustrates downlink transmission of a multicarrier signal from a base station to a communication device according to an embodiment of the present invention.
  • the frequency capture range used for frequency offset estimation of a received OFDM signal is extended by frequency shifting the received multicarrier signal at least once in the frequency domain. Thereafter a frequency offset estimation of the received signal is performed based on the extended frequency capture range so as to obtain the frequency offset estimation £ FOE . Therefore, a re-sampling (frequency shifting) method is proposed to perform frequency shift in the frequency domain so that the captured range for frequency offset can be extended.
  • the received OFDM signal has a frequency offset of ⁇ and the receiver is equipped with a frequency offset estimator up to & FFO the problem is the case in which or in other words in which the frequency offset is larger than the frequency
  • ⁇ is a residual frequency offset within ⁇ .
  • the range is extended by introducing a frequency shift so that + ⁇ 5
  • embodiments of the present invention relate to a device 10 for estimating frequency offset of a received multi carrier signal in a wireless communication system 20, the device comprises optionally at least one processor 30 adapted to: receive a signal comprising at least one Orthogonal Frequency Division Multiplexing, OFDM, symbol pair transmitted over a radio channel; extend a frequency capture range used for frequency offset estimation of said received signal by frequency shifting said received signal at least once in the frequency domain to; and estimate a frequency offset 8 TO£ of said received signal based on the extended frequency capture range.
  • the capture range is far less than the actual frequency offset error.
  • the embodiments of the present invention solve this problem of the conventional approaches by extending the capture range. Fig.
  • a DL signal is received by an antenna unit 1 1 and is converted to a baseband signal in the front end 12.
  • the time domain OFDM signal is converted to the frequency domain by an FFT unit 13.
  • the frequency of the signal is frequency shifted by passing the frequency domain signal to an FIR filter which is performed in the block "re-sampling filter” 14.
  • a frequency offset estimation is performed in block "FOE" 15 which will be further described in the following disclosure.
  • a frequency shift can be implemented in the frequency domain by a FIR Filter.
  • the filter coefficients C(m) can according to another embodiment be written in the form of,
  • N FFT is a number of Fast Fourier Transform
  • FFT points
  • N gi is a length of guard interval or cyclic prefix of said received signal
  • / is an OFDM symbol index within one sub-frame of said received signal.
  • both re-sampling filters and baseline frequency offset estimators are used for obtaining multiple frequency offset estimations e k , ⁇ k e l,2,..., N+ l ⁇ . Therefore, the present device according to this embodiment is adapted to frequency shift the received signal N times (N being an positive integer) so as to obtain N + 1 frequency offset estimations e k , ⁇ k e l,2,..., N+ l ⁇ including one frequency offset without a frequency shift, i.e. around the carrier frequency for the transmitted signal. Concatenating all frequency offset estimations together extends the total frequency capture range by N + 1 times a frequency capture range of an individual frequency offset estimation £ k . In this way adjacent frequency estimation regions are obtained.
  • the baseline frequency estimator has a certain range of frequency offset and the re-sampling filter frequency is carefully designed so that the baseline estimator can be constructed to achieve wider frequency offset capture range. In this embodiment there is no frequency estimate range overlap and thus the total range can be maximized.
  • the anticipated frequency offset range is defined which is the maximum offset that can be estimated, e.g. within +/- 0.5 of the sub-carrier spacing.
  • the target of anticipated frequency offset range is ⁇ 7 kHz or ( ⁇ 0.466 in normalized scale).
  • Two frequency hypothesis denoted as - ⁇ and ⁇ respectively, are defined in this example assuming that OFDM symbols [4, 7] are used in a LTE system. This will form a set of frequency shifts ⁇ ⁇ as
  • the receiver device may have the structure as illustrated in Fig. 6.
  • the digital OFDM baseband time domain signal is converted to the frequency domain by an FFT unit 16.
  • the three Frequency Offset Estimation (FOE), blocks 18 in Fig. 6, generate three corresponding correlation values denoted as ⁇ 15 ⁇ 2 , ⁇ 3 .
  • the selector 19 of the present device will select one out of three frequency offset hypotheses ⁇ ⁇ , ⁇ 2 , ⁇ 3 by first finding the index p from arg max
  • the frequency offset estimation is obtained by increasing the number of frequency hypothesis by having overlapping frequency estimation regions.
  • the anticipated capture range must be defined and being divided into ⁇ /+1 zones of equal frequency spacing.
  • the frequency hypotheses are thereafter placed at the centre of each zone as shown in Fig. 7. It can be observed from Fig. 7 that the capture range of each zone is -0.093, 0.093 which is smaller than the individual estimator capture range -0.155, 0.155.
  • the present device 10 is arranged to frequency shift the received signal N times so as to obtain N + 1 frequency offset estimations e k , ⁇ k e l,2,..., N+ l ⁇ together extending the frequency capture range by less than N + l times a frequency capture range of an individual frequency offset estimation £ k .
  • the receiver device 50 will only trust the estimator which provides the frequency estimates within its zone. Otherwise, the results are discarded. Finally, the best estimator is obtained by finding the highest absolute correlation magnitude from those trusted estimator outputs. In Fig. 7 this procedure is shown. In region 1 , a FFO estimate, the circle sign in Fig. 7, is obtained that falls within the same region, therefore this value is trusted. For region 2, the FFO estimate, i.e. the plus sign in Fig. 7, falls within the zone of the first estimator, therefore this estimate is not trusted as it is too far away from the centre of region 2. Also, the two regions to the right, i.e.
  • regions 4 and 5 are producing FFO estimates that are too far away from the centres of the regions, and are therefore discarded.
  • Region 3 in the middle produces a valid FFO estimate, i.e. the triangle sign.
  • the final output will be either the FFO estimate shown in the circle sign or the triangle sign depending on which one that has the largest correlation magnitude according to an embodiment.
  • Likelihood (ML) function is used for selecting the frequency offset estimation £ FOE of the received signal.
  • the method described in Fredrik usek, Basuki E. Priyanto, "Karhunen Loeve based Maximum Likelihood estimation of frequency offsets in OFDM systems using pilots", Patent Application EP13198573.1 is used but with a slightly different approach. Rather than using correlation of CRS symbols the present idea is based on constructing the likelihood function. Maximizing this function would qualify as optimal
  • a M a fixed matrix.
  • the receiver can produce more channel estimates based on multiple pairs of transmit and receive antennas.
  • the LTE system has been designed so that each antenna port can transmit CRS symbols. Hence, more correlation outputs can be generated according to,
  • the present receiver device 10 is further arranged to compute correlation values of channel estimates for at least one OFDM symbol pair for each MIMO stream; thereafter linearly combine the computed correlation values for each MIMO stream; and using the combined correlation values for estimating the frequency offset & FOE of the received signal.
  • more than one OFDM symbol pair can be used for estimating the frequency offset.
  • more than one OFDM symbol pairs are used as the input to the frequency offset estimator.
  • the reference symbols are located at OFDM symbol locations 0, 4, 7 and 1 1 .
  • many combinations of OFDM symbols pairs can be formed, i.e., [0, 4], [4, 7], [4, 1 1], [0, 7], etc. It is noted that different OFDM symbol pairs result in different frequency offset ranges and thus it must be uniquely treated in order to combine the result.
  • the device 10 needs to predefine the number of L OFDM symbol pairs to be used for estimation.
  • f Rm n is frequency range of the estimation using symbol m and n
  • f R4 7 equals to 0.31 1
  • f R0 4 equals to 0.233
  • N and M are integer values.
  • Those frequency hypotheses should also be within a predefined anticipated frequency offset range (e.g., ⁇
  • Further embodiments of the present invention also relate to devices and methods for complexity reduction of the present frequency offset estimation solutions.
  • the objective of complexity reduction is to reduce the complexity with relatively low performance degradation.
  • the performance degradation can be contributed from higher probability of false detection and/or increasing RMS error due to less number correlation for noise averaging purpose.
  • the main focus is then to reduce the number of correlations and avoiding an increase in the probability of false region detection.
  • a first complexity reduction method is almost identical to the above methods and devices for frequency offset estimation except that the number of correlations in all sets is reduced by using a reduced number of sub-carriers of the at least one OFDM symbol pair for correlating channel estimates.
  • Each branch after FFT outputs perform correlation for both 2 pair of symbols; symbol # 0 and symbol # 4 and symbol # 4 and symbol # 7.
  • the phase rotation measured from two OFDM symbol with the distance of ⁇ symbols can be expressed as,
  • OFDM symbols # 4 and # 7 are used at the branches with re-sampling filter (N branches).
  • the OFDM symbol pair used for each frequency offset estimation e k , ⁇ k e l, 2, ..., N+ l ⁇ (branch) is the same OFDM symbol pair or has the same symbol distance.
  • This embodiment can be further improved by using additional OFDM symbol pairs for correlating channel estimates for a frequency offset estimation £ k associated with the transmit carrier frequency for said received signal. In this case the estimation branch without re-sampling uses two OFDM symbol pair.
  • ⁇ ⁇ - 0.466,8 04 - 0.233, 8 04 , ⁇ + 0.233, ⁇ 04 + 0.466 ⁇ .
  • the frequency offset estimation was in principle performed in 1 sub-frame. However, it can also be extended to more than 1 sub-frame by performing time domain averaging.
  • the anticipated frequency offset range was within ⁇ 7 kHz and ⁇ 10 kHz.
  • the common simulation parameters that were used are given in Table 1.
  • Fig. 1 1 shows the performance for various schemes assuming that the frequency offset is within ⁇ 7 kHz.
  • the single channel case performs worst.
  • the performance can be improved by using multiple channels (MIMO) and also using more symbol combinations, both [0, 4] and [4, 7].
  • MIMO with minimum distance MIMO [0, 4], [4, 7]
  • the ML method has better results for low SNR values.
  • the best performance was achieved by performing time domain averaging.
  • the result of "MIMO-ML [0, 4], [4, 7] - 4 Sub Frames" setup indicated it is quite close to the results with restricted frequency offset ( ⁇ 2.33 kHz).
  • Fig. 12 shows the performance for various schemes assuming that the frequency offset is within ⁇ 10 kHz. It can be seen the present device and method is still performing well even when the frequency offset has been extended to ⁇ 10 kHz. There is only a small penalty observed in most of the cases.
  • the performance of using the MD method is completely offset. It is mainly because the MD method requires proper placement of frequency shift which is for re-sampling filter.
  • the MD method used here is designed for three zones which can theoretically cover up to 7 kHz frequency offset.
  • the present invention also relates to methods for frequency offset estimation and complexity reduction.
  • Any method according to the present invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method.
  • the computer program is included in a computer readable medium of a computer program product.
  • the computer readable medium may comprises of essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.
  • Fig. 13 illustrates a method according to an embodiment of the present invention.
  • the method for estimating a frequency offset of a received multi carrier signal in a wireless communication system 20 comprises the steps of: receiving 100 a signal comprising at least one Orthogonal Frequency Division Multiplexing, OFDM, symbol pair transmitted over a radio channel; frequency shifting 200 said received signal at least once in the frequency domain so as to extending a frequency capture range used for frequency offset estimation of said received signal; and estimating 300 a frequency offset £ FOE of said received signal based on the extended frequency capture range.
  • OFDM Orthogonal Frequency Division Multiplexing
  • the present estimation device 10 and communication device 50 each comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for executing the present method.
  • means, units, elements and functions are: processors, memory, encoders, decoders, mapping units, multipliers, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, Rx unit, Tx unit, DSPs, MSDs, TCM encoder, TCM decoder, interfaces, communication protocols, etc. which are suitably arranged together.
  • the processors of the present user device or access node device may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions.
  • CPU Central Processing Unit
  • ASIC Application Specific Integrated Circuit
  • microprocessor may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.
  • the processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.
  • Fig. 14 shows a device 10 according to the present invention.
  • the device 10 comprises in this case a processor unit 30 coupled to an input unit and an output unit.
  • the processor 30 is arranged to receive a signal (or a representation of a signal) comprising at least one OFDM symbol pair.
  • the processor 30 is further arranged to process the signal as described in this application in conjunction with the various embodiments to obtain a frequency offset estimation which can be outputted for further processing such as correcting the signal from the frequency offset.
  • the device 10 also comprises a memory coupled to the processor for storing data.
  • the memory may also include program instructions to be executed in the processor.
  • the device 10 may be a standalone device or be integrated in communication device 50.
  • Fig. 15 shows a communication device 50 according to an embodiment of the present invention which comprises at least one frequency offset estimation device 10 according to an embodiment of the present invention.
  • the communication device 50 in Fig. 15 receives a downlink multicarrier signal from a base station in this case.
  • the communication system 20 may be a cellular multicarrier system such as LTE but the present invention is not limited to an LTE system.
  • LTE system the communication device 50 is a UE but can be any communication device arranged to receive radio communication signals transmitted in a multicarrier system using OFDM symbols, such as terminals or general receiver devices.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Transmission System (AREA)

Abstract

La présente invention concerne un dispositif pour estimer un décalage de fréquence d'un signal reçu. Le dispositif est conçu pour : recevoir un signal comprenant au moins une paire de symboles de multiplexage par répartition orthogonale de la fréquence (OFDM) transmise sur un canal radio; étendre une plage de capture de fréquence utilisée pour une estimation de décalage de fréquence dudit signal reçu par décalage de fréquence dudit signal reçu au moins une fois dans le domaine fréquentiel; et estimer une formule de décalage de fréquence (I) dudit signal reçu sur la base de la plage de capture de fréquence étendue. En outre, la présente invention concerne également un procédé correspondant, un dispositif de communication comprenant un tel dispositif, un programme d'ordinateur et un produit programme d'ordinateur.
EP14716796.9A 2014-04-08 2014-04-08 Dispositif pour estimer un décalage de fréquence dans un multiplexage par répartition orthogonale de la fréquence (ofdm) et procédé correspondant Withdrawn EP3130122A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2014/057098 WO2015154801A1 (fr) 2014-04-08 2014-04-08 Dispositif pour estimer un décalage de fréquence dans un multiplexage par répartition orthogonale de la fréquence (ofdm) et procédé correspondant

Publications (1)

Publication Number Publication Date
EP3130122A1 true EP3130122A1 (fr) 2017-02-15

Family

ID=50478833

Family Applications (1)

Application Number Title Priority Date Filing Date
EP14716796.9A Withdrawn EP3130122A1 (fr) 2014-04-08 2014-04-08 Dispositif pour estimer un décalage de fréquence dans un multiplexage par répartition orthogonale de la fréquence (ofdm) et procédé correspondant

Country Status (3)

Country Link
EP (1) EP3130122A1 (fr)
CN (1) CN105122752B (fr)
WO (1) WO2015154801A1 (fr)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3410661B1 (fr) 2016-01-26 2021-09-01 Sony Group Corporation Dispositif et procédé
WO2017157454A1 (fr) * 2016-03-18 2017-09-21 Huawei Technologies Co., Ltd. Récepteur et procédé destinés à estimer le décalage de fréquence de porteuse dans un signal de modulation multi-porteuse
WO2017157453A1 (fr) * 2016-03-18 2017-09-21 Huawei Technologies Co., Ltd. Récepteur et procédé permettant l'estimation du décalage de fréquence porteuse dans un signal de modulation multiporteuse
US10104630B2 (en) * 2016-07-08 2018-10-16 Intel IP Corporation Methods and devices for time and frequency offset estimation
US10419248B2 (en) 2016-12-14 2019-09-17 Samsung Electronics Co., Ltd Method and apparatus for frequency domain inter-carrier interference compensation
CN115176446B (zh) * 2020-02-07 2023-12-05 哲库科技(上海)有限公司 用于基于循环前缀的时间和/或频率校正的装置和方法
CN112710899B (zh) * 2021-03-29 2021-07-13 国网江西省电力有限公司供电服务管理中心 一种改进增益有限脉冲响应滤波的电网信号频率检测方法
CN113839900B (zh) * 2021-10-09 2024-06-07 上海东软载波微电子有限公司 载波频偏估计方法及装置、计算机可读存储介质
EP4277218A1 (fr) * 2022-05-11 2023-11-15 Nokia Solutions and Networks Oy Estimation et réduction de décalage de fréquence
CN116418636B (zh) * 2023-06-08 2023-08-18 芯迈微半导体(上海)有限公司 一种无线通信的增强的多普勒扩展估计方法和系统

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3638107B2 (ja) * 1999-12-09 2005-04-13 Ｋｄｄｉ株式会社 スペクトル拡散信号復調装置
US7684473B2 (en) * 2005-06-01 2010-03-23 Qualcomm Incorporated Receiver for wireless communication network with extended range
CN1719818B (zh) * 2005-07-08 2010-06-23 广州海格通信集团股份有限公司 一种正交频分复用系统的采样频率偏差跟踪信号处理装置及方法
CN101132385A (zh) * 2007-09-24 2008-02-27 杭州国芯科技有限公司 正交频分复用接收机中消除大采样时钟偏差的方法
US9071493B2 (en) * 2009-06-29 2015-06-30 Qualcomm Incorporated Dual frequency tracking loop for OFDMA systems
CN101938443B (zh) * 2009-06-30 2013-07-03 瑞昱半导体股份有限公司 频偏取得的方法及其相关装置
KR101042737B1 (ko) * 2010-04-22 2011-06-20 성균관대학교산학협력단 오에프디엠 시스템에서 파일럿 상관값 기반 시간 옵셋에 강인한 정수 주파수 옵셋 추정 방법 및 장치

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2015154801A1 *

Also Published As

Publication number Publication date
WO2015154801A1 (fr) 2015-10-15
CN105122752B (zh) 2018-10-19
CN105122752A (zh) 2015-12-02

Similar Documents

Publication Publication Date Title
WO2015154801A1 (fr) Dispositif pour estimer un décalage de fréquence dans un multiplexage par répartition orthogonale de la fréquence (ofdm) et procédé correspondant
Schaich Filterbank based multi carrier transmission (FBMC)—evolving OFDM: FBMC in the context of WiMAX
EP1689140A1 (fr) Dispositif et procédé pour la compensation d'un décalage de fréquence dans un système de communication sans fil
JP5803795B2 (ja) 受信装置、周波数偏差算出方法及びコンピュータプログラム
JP6118616B2 (ja) 受信機および同期補正方法
CN102694763A (zh) 一种用于td-lte系统整数倍频偏估计的方法
CN109714289B (zh) 一种cp-ofdm系统的频偏估计方法及装置
WO2001020831A1 (fr) Dispositif de communication ofdm et procede de detection
JP5242599B2 (ja) マルチキャリアシステムにおけるチャネル推定のためのタイミング調整
Zhu et al. Carrier frequency offset estimation for OFDM systems with null subcarriers
KR20080028625A (ko) 멀티캐리어 통신 시스템에서 공통 위상 에러 보정 장치 및방법
WO2013001474A1 (fr) Estimation d'un décalage de fréquence entre une station de base et un terminal mobile
US8761326B2 (en) Compensating devices and methods for detecting and compensating for sampling clock offset
CN111107028B (zh) 一种5g系统基于pss与sss联合的频偏估计方法
US8520777B2 (en) Operation of user equipment when control and data information are supplied by different radio units
JP2010062865A (ja) 復調装置
US8804804B1 (en) Estimation and compensation for carrier frequency offset and sampling clock offset in a communication system
Nasraoui et al. A simply-differential low-complexity primary synchronization scheme for 3GPP LTE systems
CN108156104B (zh) 一种基于cp与crs联合的小数倍频偏估计方法
US7583770B2 (en) Multiplex signal error correction method and device
WO2002103974A1 (fr) Correction de frequence avec ajustement de phase symetrique dans chaque symbole en multiplexage par repartition orthogonale de la frequence (mrof)
CN104904172B (zh) 估算和去除dc偏移的方法
WO2011117673A1 (fr) Structure de préambule pour une acquisition de données de temps et de fréquence dans des systèmes ofdm comprenant une pluralité de fortes interférences en bande étroite
US7876844B2 (en) Apparatus and method for determining positions of pilot sub-carriers in an OFDM symbol
Sagong et al. A novel blind interference cancellation receiver for LTE uplink SC-FDMA systems

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20150928

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAX Request for extension of the european patent (deleted)
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Effective date: 20180911