WO2011026524A1 - Estimation de décalage de fréquence ou de temps dans un récepteur multiporteuse - Google Patents

Estimation de décalage de fréquence ou de temps dans un récepteur multiporteuse Download PDF

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Publication number
WO2011026524A1
WO2011026524A1 PCT/EP2009/061506 EP2009061506W WO2011026524A1 WO 2011026524 A1 WO2011026524 A1 WO 2011026524A1 EP 2009061506 W EP2009061506 W EP 2009061506W WO 2011026524 A1 WO2011026524 A1 WO 2011026524A1
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WIPO (PCT)
Prior art keywords
correlations
error
symbols
span
frequency
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PCT/EP2009/061506
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English (en)
Inventor
Arne Birger Husth
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Nokia Corporation
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Priority to PCT/EP2009/061506 priority Critical patent/WO2011026524A1/fr
Publication of WO2011026524A1 publication Critical patent/WO2011026524A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier 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
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking
    • 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
    • H04L27/2662—Symbol synchronisation

Definitions

  • the invention relates to reception of symbols, and more particularly to error estimation in reception of symbols.
  • a user can access a communication system or communicate directly with other users by means of an appropriate communication device.
  • a communication device can thus be seen as a facility that enables communication sessions between two or more parties.
  • the communications may comprise, for example, communication of voice, electronic mail (email), text message, multimedia, other data and so on.
  • a communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling the communications. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet.
  • a communication device of a user is often referred to as user equipment (UE).
  • UE user equipment
  • a communication system facilitating the communications can be provided for example by means of a communication network and one or more compatible communication devices.
  • the communication network may be a large network proving nationwide cover, continent wide cover or even global cover, or be provided by a local network.
  • wireless communication system at least a part of communications between at least two stations occurs over a wireless link.
  • wireless systems include public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN).
  • PLMN public land mobile networks
  • WLAN wireless local area networks
  • a user can access the communication system via an access system thereof.
  • the access system can be provided, for example, by a base station or a group of base stations and associated controllers.
  • a communication system and associated devices typically operate in accordance with a given standard and/or specifications which set out what the various entities associated with the system are permitted to do and how that should be achieved.
  • the standard or specification may define if a communication device is provided with a circuit switched carrier service or a packet switched carrier service or both.
  • Communication protocols and/or parameters which shall be used for the connection are also typically defined.
  • the multiplexing techniques and/or the type or types of the access technology compatible communication devices shall use can be defined.
  • a communication device typically needs to be synchronized in time and/or frequency with the other party of the communication, typically a communication network.
  • a communication device can be provided with an oscillator such that its frequency and/or timing can be synchronized to the network.
  • An example of such is a crystal oscillator.
  • oscillators are not always as accurate as they should be.
  • an oscillator can have a certain amount of drift with time. This can be the case for example in temperature gradient conditions.
  • Particular offset estimators have been developed to correct for the errors. It could be beneficial to be able to estimate a relatively large frequency offset between an internal oscillator of a receiving communication device and the signal received from another entity, for example from a base station.
  • DRX discontinuous reception
  • a frequency offset estimator of the communication device is limited to a relatively small range then it may be necessary for the communication device to start a re- synchronization process in any one of these scenarios.
  • a re-synchronization can take time, and thus can result a loss of service for the user for this time duration.
  • Embodiments of the invention aim to address one or several of the above issues.
  • a method comprising receiving symbols in a receiver apparatus, determining first correlations for a first span of the symbols, determining second correlations for a second span of the symbols, and estimating an error based on combined processing of the first and second correlations.
  • an apparatus comprising means for determining first correlations for a first span of symbols and for determining second correlations for a second span of the symbols, and means for estimating an error based on combined processing of the first and second correlations.
  • an apparatus comprising at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, determine first correlations for a first span of symbols and second correlations for a second span of the symbols, and to estimate an error based on combined processing of the first and second correlations.
  • error estimation range is expanded by means of the combined processing of the first and second correlations.
  • the error comprises a frequency error.
  • the error in frequency can be an error in a reference oscillator.
  • the frequency error may occur in a reference oscillator of a wireless modem.
  • the error comprises a timing error. Both errors may be estimated.
  • the determining of the first correlations may comprise correlating channel estimates for the first span.
  • the determining of the second correlations may comprise correlating channel estimates for the second span.
  • the estimating of error may comprise determining information about the phases of the correlations and estimating the error based on processing of said information to generate an error parameter.
  • a phase vector may be determined based on the phases of the first correlations and the second correlations, and the error parameter may then be computed based on the phase vector.
  • Phase information may be computed by means of an arcus tangent function.
  • the error parameter can be computed as a weighted difference between the phase information for the first and second correlations.
  • a phase offset may be determined by comparing an error parameter to predefined thresholds.
  • the correlations formed over a plurality of spans may be averaged.
  • the first span may comprise the time of three consecutive symbols of a cyclic slotted transmission.
  • the second span may comprise the time of four consecutive symbols of the cyclic slotted transmission.
  • a timing error may be computed based on phases of the first and second correlations between channels estimates for a first frequency span and a second frequency span.
  • the symbols may comprise orthogonal frequency division multiplexing (OFDM) symbols.
  • the apparatus wherein the embodiments are implemented may be configured to operate in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN).
  • E-UTRAN Evolved Universal Terrestrial Radio Access Network
  • a computer program comprising program code means adapted to perform one or more of the herein disclosed methods is also provided.
  • the computer executable program code components can be stored on a computer-readable storage medium.
  • Figure 1 shows an example of a communication system wherein below described examples of the invention may be implemented
  • Figure 2 shows an example of a communication device
  • Figure 3 shows, as an example, a schematic block chart of a receiver apparatus
  • Figure 4 shows two different time spans provided by two consecutive slots
  • Figure 5 shows an example of phase of two different correlations
  • Figure 6 shows an example of an error parameter as a function of frequency error
  • Figure 7 is a flowchart illustrating an exemplary embodiment
  • Figure 8 shows, as an example, a schematic block chart of another receiver apparatus.
  • a mobile communication device can be used for accessing various services and/or applications provided via a communication system.
  • a wireless interface can be provided between mobile communication devices 1 and other stations. More particularly, in the Figure 1 example mobile communication devices 1 are provided wireless access via a base station 12 or similar wireless transmitter and/or receiver node of an access system 10. Each mobile communication device 1 and base station may have one or more channels or subchannels open at the same time and may receive signals from more than one source. It is noted that although only one access system 10 is shown in Figure 1 , a number of access systems, such as radio access networks, can be provided. An access system and a base station is typically controlled by at least one appropriate controller so as to enable operation thereof and management of mobile communication devices in communication with the base station.
  • control apparatus can be interconnected with other control entities.
  • the controller is shown to be provided by block 13.
  • a control apparatus for a base station is typically provided with memory 15 and at least one data processor 14. It shall be understood that the control apparatus and functions may be distributed between a plurality of controller units.
  • a functionality of the control apparatus at the communication system side is to maintain certain common system features such as timing or clock and frequency. Information of these features or signals by means of which the mobile communication devices can be synchronized thereto are sent to the mobile devices.
  • the communication devices 1 can synchronize themselves with the system based on these signals, often called as reference signals or pilot signals.
  • a particular example of access systems is the radio access network (RAN) of the third generation mobile communication system, sometimes termed as the Universal Mobile Telecommunications System (UMTS).
  • RAN radio access network
  • UMTS Universal Mobile Telecommunications System
  • LTE long-term evolution
  • UMTS Universal Mobile Telecommunications System
  • 3GPP 3 rd Generation Partnership Project
  • LTE-Advanced A further development of the LTE is referred to as LTE-Advanced.
  • the LTE employs a mobile access architecture known as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN).
  • E-UTRAN Evolved Universal Terrestrial Radio Access Network
  • Other examples of radio access systems include those provided by base stations of access systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access).
  • WLAN wireless local area network
  • WiMax Worldwide Interoperability for Microwave Access
  • the access system 10 is connected to a wider communications network 20.
  • a communication system may be provided by one or more of such networks and the elements thereof.
  • One or more gateways may be provided for interconnecting the different networks.
  • FIG. 2 shows a schematic, partially sectioned view of a communication device 1 that can be used for communication with a communication system.
  • An appropriate mobile communication device may be provided by any device capable of sending and receiving wireless signals. Non-limiting examples include a mobile station (MS), a portable computer provided with a wireless interface card or other wireless interface facility, personal data assistant (PDA) provided with wireless communication capabilities, or any combinations of these or the like.
  • a mobile communication device may be used for voice and video calls, for accessing service applications and so on.
  • the mobile device 1 may receive signals over an air interface 11 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting signals.
  • a transceiver component is designated schematically by block 7.
  • the transceiver apparatus may be provided for example by means of a radio part and associated antenna arrangement.
  • the antenna arrangement may be arranged internally or externally to the mobile device.
  • Appropriate modem apparatus 9 is also provided to enable modulation and demodulation of wireless signals.
  • the modem apparatus can comprise an oscillator
  • a communication device is also typically provided with at least one data processing entity 3, at least one memory 4 and other possible components for use in software aided execution of tasks it is designed to perform, including control of access to and communications with other parties, such as access systems and/or other communication devices.
  • the data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 6.
  • the user may control the operation of the mobile device by means of a suitable user interface such as key pad 2, voice commands, touch sensitive screen or pad, combinations thereof or the like.
  • a display 5, a speaker and a microphone are also typically provided.
  • a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories and peripherals, for example hands-free equipment, thereto.
  • FIG. 3 A block chart showing an example of how signals received by an antenna can be processed by means of a receiver apparatus 30 is shown in Figure 3.
  • received signals can be guided via a radio frequency (RF) component 31 to an analogue to digital converter (ADC) 32.
  • ADC an analogue to digital converter
  • the digitized signal can then be subjected to symbol extraction at block 33.
  • the symbols can be input into a Fast Fourier Transform (FFT) block 34 where after data symbol detection can follow at block 35. Pilot symbols can be extracted between the FFT block 34 and the detection block 35, the extraction function being designated by block 36.
  • the extracted pilot symbols can be fed into a channel estimator function 37.
  • the channel estimator processes the extracted pilot symbols with known pilot symbols to provide channel estimations.
  • Figure 3 further shows a reference oscillator 38 and a baseband clock 39.
  • correlations of the channel estimates over a time span are computed at block 40. Examples of appropriate computations of the correlations are described in more detail later in this description.
  • the correlations may be subjected to averaging at block 41.
  • a frequency error can then be calculated at block 42 based on the results of the correlations at block 40. Examples for these computations are also given later in this description.
  • the calculation result can be fed into an automatic frequency control (AFC) block 43 providing control on the reference oscillator 38.
  • the automatic frequency control (AFC) converts the frequency error estimate into an appropriate tuning control signal for the oscillator, in order to close the frequency control loop and bring the oscillator to the desired frequency.
  • Orthogonal frequency division multiplexing is a widely used technique for high data rate transmission, both on wireless and wired connections.
  • OFDM orthogonal frequency division multiplexing
  • a large number of orthogonal sub-carriers are used to carry data, the data being divided into several parallel data streams or channels, one for each sub-carrier.
  • the OFDM technique makes use of a set of overlapping but orthogonal sub-carriers to reach high spectrum efficiency.
  • orthogonal frequency division multiple access has been proposed in many broadband wireless systems to provide more flexible wireless access scheme and to take more advantage of diversity gain by allocating a user a set of permutation-driven interleaved sub- carriers that provide a large sub-carrier spacing for each user in a multiuser system.
  • OFDM based communication systems can suffer from synchronization errors, such as misalignments, discordances between the oscillators, and Doppler shifts. Synchronization errors can even remove the orthogonality and thus seriously deteriorate the performance of the OFDM based system.
  • an OFDM enabled communication device or station is typically provided with an offset or error estimator to monitor and correct the errors in order to maintain the synchronization of the communication device and another device.
  • a OFDM capable receiver apparatus can estimate the error based on fast fourier transform (FFT).
  • FFT can be used for calculations of frequency domain modulation symbols from time samples of a OFDM symbol as the fast fourier transform (FFT) provides an efficient algorithm to compute a discrete fourier transform (DFT) and its inverse.
  • DFT discrete fourier transform
  • pilot modulation symbols are complex modulation symbols that are known to the communication device and can thus be used for estimation purposes.
  • Reference signals are typically sent in a regular time pattern with known time spacing.
  • the spacing can comprise the time used for transmitting three or four OFDM symbols (including cyclic prefix times).
  • such symbols are sent in symbols 0 and 4 of each consecutive slot, and thus time spans of four and three symbols can be provided.
  • Appropriate control apparatus provided in the communication device can calculate the so-called channel estimates.
  • the channel estimates can be calculated by dividing the received pilot symbols by the known complex pilot values. For every pilot symbol received a channel estimate can be calculated. If the reference oscillator has a frequency error this error can be estimated by estimating a phase change between two channel estimates that spans a certain time lag. The phase change between the two channel estimates spanning a certain time lag can be calculated from the complex correlation of the two channel estimates.
  • a possibility to estimate the error is to estimate the phase change in channel estimates over the smallest possible time span or lag.
  • pilots are transmitted for every three and four OFDM symbols in the consecutive slots of seven symbols, as shown in Figure 4.
  • a symbol is typically understood as being a state or condition of a communication channel that persists for a fixed period of time.
  • a symbol duration time can be measured by means of an oscilloscope.
  • a sending device can place symbols on the channel at a fixed symbol rate in slots, and the receiving device then has the job of detecting the sequence of symbols in order to reconstruct the transmitted data.
  • a direct correspondence between a symbol and data may exist for example such that each symbol may encode one or several binary bits.
  • the symbols can be sent in predefined time intervals that are called slots.
  • symbols 52 in slots 50 and 51 are provided with order numbers from 0 to 6, the pilots are transmitted in symbols 0 and 4 in the E-UTRAN example of Figure 4. These symbols can be called reference signals or pilot symbols 55.
  • Combining the pilot in symbol 0 with the pilot in symbol 4 gives Iag4 correlation.
  • Combining the pilot in symbol 4 with the pilot in symbol 0 of the next slot gives Iag3 correlation. This enables calculations of correlations for a time lag of three symbols (Iag3) 53 and a time lag of four symbols (Iag4) 54.
  • the time spacing between symbols carrying the reference signals sets the limit for the maximum frequency error that can be estimated. This is so because the phase error is typically estimated within the range of ⁇ ⁇ .
  • the maximum frequency error that can be estimated is thus: where ⁇ ⁇ ⁇ is the time between the two channel estimates used for the correlation.
  • the pilot position in frequency domain can change from one reference signal to another.
  • Channel estimates interpolated in frequency domain can be used in such situations in order to calculate correlations with lags of three and four symbols time.
  • different methods can be used, for example using linear interpolation between channel estimates from pilot symbols on the two adjacent subcarrier frequencies.
  • Another possibility for finding the "interpolated channel estimates” is to use a smoothing filter used on the channel estimates in frequency domain.
  • a smoothing filter is used another option is to use the output of the filter for all the pilot frequencies used for calculation of channel estimate correlations.
  • interpolated channel estimates, filtered channel estimates and real channel estimates as this would not assist in understanding the examples of the invention.
  • correlations can also be calculated for example using a lag of one slot that equals the time of seven symbols.
  • Z(AT pjl ) The correlation between channel estimates at a distance AT piI is called Z(AT pjl ) .
  • Z(AT p ) can be calculated as the sum of all correlations between channel estimates in the two OFDM symbols:
  • H is the channel estimate and channel estimates H at a distance AT pil are indexed 1 and 2.
  • the k index spans the number of pilots
  • symbols can be received at 100.
  • the symbols can be provided for example by a pilot extraction function.
  • the error estimation apparatus can then determine at 102 and 104 the respective first and second correlations for first and second time spans.
  • the error estimation can then be provided at 106 based on combined processing of the first and second correlations.
  • a frequency error estimation range by generating a frequency error estimate based on information of correlations for different time lags.
  • Iag3 correlations and Iag4 correlations of the above example can be combined in order to extend the estimation range to what corresponds to a lag of just one symbol (Iag1) correlations.
  • Iag1 correlations can be used to increase the estimation range.
  • the extension can be of the order of 3 or 4 from using one lag.
  • the combined processing can also be, for example, to improve the accuracy of error estimations.
  • a possible way to compute the error based on combination of different time lags is based on use of an arcus tangent (AT) function, sometimes called the inverse tangent. More particularly, an AT function can be used for calculation of the phase of the correlation.
  • the complex correlation of each lag will have a real component and an imaginary component.
  • An arcus tangent function that takes a complex number as argument can be used to ensure that the valid range of the arcus tangent (AT) function is from - ⁇ to ⁇ radians.
  • phase of Iag3 correlations (AT3) and phase of Iag4 correlations (AT4) for a frequency error range from -7000 Hz to +7000 Hz is illustrated in Figure 5.
  • the complex Iag3 correlation, termed herein C3 rotates three full turns when the frequency error goes from -7000 Hz to +7000 Hz.
  • the complex Iag4 correlation, termed herein C4 rotates four full turns when the frequency error goes from -7000 Hz to +7000 Hz.
  • the angle of the complex correlation C3 is called AT3 and the angle of the complex correlation C4 is called AT4.
  • complex Iag2 correlation, C2 would rotate two turns, and so on.
  • the arcus tangent (AT) function is a periodic function, but if we look at the phase vector (AT3, AT4) as a function of frequency error, then this function can be considered as an injective function of the frequency error inside the shown range from -7000 Hz to +7000 Hz.
  • a single correlation, for example C3, would not give sufficient information for finding the frequency error in the extended range from -7000 Hz to +7000 Hz because three different frequency errors would result in the same value of C3 in this range.
  • the three solutions are termed herein f3_0, f3_1 and f3_2.
  • Iag4 correlations, C4 would not give sufficient information either, because in the range from -7000 Hz to +7000 Hz four different frequency errors would result in the same value of C4.
  • the four solutions are termed herein f4_0, f4_1 , f4_2 and f4_3.
  • the frequency error can be determined by calculating an error parameter, termed herein an AT parameter from equation (7):
  • AT(f) can be calculated as a weighted difference between AT3 and AT4 for the purpose of getting constant output numbers that can be used for comparison to predefined thresholds.
  • the resulting AT parameter for example for the (AT3.AT4) dataset is illustrated in Figure 6 showing a plot of the AT(f) function when f is varied from -7000 Hz to 7000 Hz.
  • the values of Figure 6 are calculated using equation (7), AT3 and AT4 being functions of the frequency error f. Since the AT(f) function gives distinct and different values for the different frequency error ranges this means that the AT(f) function can be seen as is a kind of injective function in regard to range detection. In other words, an inverse function to AT(f) exists that can be used for frequency error range detection.
  • the AT parameter can have one of seven possible values (ATo to AT 6 ) when the frequency error goes from -7000 Hz to +7000 Hz.
  • the AT parameter is rather an estimate, since it is likely to include at least some noise and thus may not exactly match one of the seven possible values.
  • the AT estimate can be formed to provide a value that can be used in determining the one of the seven ranges where the frequency error is likely to be.
  • a simple approach to provide this is to choose the one of the seven values AT 0 to AT 6 that is closest to the AT estimate. This value is called herein as AT n .
  • a phase offset ⁇ can be determined based on mapping the value to the ranges.
  • the AT values can be mapped to the ⁇ values of Table 1 .
  • a frequency error estimate with optimized detection range can then be calculated using equation (8) below, where AT pi is the spacing between pilots used for Iag3 correlations and ⁇ iZ4 is the spacing between pilots used for Iag4 correlations.
  • ATN the phase of the first correlations
  • ⁇ the timing between symbols used for the first correlations
  • ⁇ the timing between symbols used for the second correlations
  • a possible another use of the method described herein is estimation of timing error in the timebase of a receiver apparatus.
  • a block diagram corresponding to Figure 3 but showing an example for a timing error estimation and correction circuit is shown in Figure 8.
  • the radio components 31 to 37 of the receiver apparatus of Figure 8 can be similar to those of Figure 3, and thus the description thereof is not repeated here.
  • the correlations may be subjected to averaging at block 81 prior to input into the error calculation block.
  • a timing correction functionality provided by block 83 may then provide appropriate control on the reception of symbols, for example on symbol extraction at block 33. If Z(AF pil ) is the correlation between channel estimates at a frequency distance AF , then the timing offset estimate can be calculated from: offset ZZ(AF ) (10)
  • the timing estimation also has a limited range, given by the distance of six subcarriers of the pilots. If the distance could be made smaller the timing detection range would be larger. If the pilots instead of being transmitted every sixth subcarrier are transmitted in a slightly irregular pattern, for example if the distance is alternated between five and seven subcarriers, then it is possible to calculate both Iag5 and Iag7 correlations and thereby extend the timing estimation range to what corresponds to Iag1 correlation, as described above with reference to the frequency error estimation.
  • the position of the pilots symbols in a frequency domain may change from one reference signal to the next.
  • the pilots in a reference signal are placed exactly between the frequencies of the pilots in the previous reference signal.
  • This makes it possible to calculate "interpolated channel estimates" for the purpose of forming correlations with half the frequency spacing of the reference signal pilot spacing.
  • the timing estimator this effectively increases the estimation range to what corresponds to Iag3 correlations.
  • Using channel estimate correlations with a distance of three subcarriers results in the maximum detectable timing error of:
  • a receiver apparatus may be provided with a frequency error estimation circuit and a timing error estimation circuit.
  • a receiver apparatus may be provided with both a timing error and frequency error estimation and correction apparatus, for example with the estimation and correction circuits of Figures 3 and 8.
  • the computations and other functions of the apparatus may be provided by means of an appropriate circuit or circuits and/or one or more data processors.
  • the described functions may be provided by separate processors or by an integrated processor.
  • the data processing may be distributed across several data processing modules.
  • a data processor may be provided by means of, for example, at least one chip. Appropriate memory capacity can also be provided in the relevant control apparatus.
  • An appropriately adapted computer program code product or products may be used for implementing the embodiments, when loaded on an appropriate data processing apparatus, for example in a data processing apparatus of the mobile communication device 1 of Figure 2.
  • the program code product for providing the operation may be stored on, provided and embodied by means of an appropriate carrier medium.
  • An appropriate computer program can be embodied on a computer readable record medium.
  • All or part of the calculations can also be implemented in an application-specific integrated circuit ASIC.
  • An application-specific integrated circuit (ASIC) is typically customized for a particular use.
  • ASICs can include processor and memory blocks including read-only memories (ROM), random access memories (RAM), electrically erasable programmable read-only memories (EEPROM), Flash and other building blocks.

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Abstract

L'invention porte sur une estimation d'erreur dans un appareil récepteur. Dans le procédé décrit, après que des symboles ont été reçus, des première et seconde corrélations sont déterminées pour une première plage et une seconde plage des symboles, respectivement. Une erreur est ensuite estimée sur la base d'un traitement combiné des première et seconde corrélations.
PCT/EP2009/061506 2009-09-04 2009-09-04 Estimation de décalage de fréquence ou de temps dans un récepteur multiporteuse WO2011026524A1 (fr)

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WO2013167740A1 (fr) * 2012-05-11 2013-11-14 Neul Ltd Procédé et appareil pour estimer des erreurs de fréquence

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
WO2013167740A1 (fr) * 2012-05-11 2013-11-14 Neul Ltd Procédé et appareil pour estimer des erreurs de fréquence
CN104641610A (zh) * 2012-05-11 2015-05-20 纽尔有限公司 用于估计频率误差的方法和装置
US9516616B2 (en) 2012-05-11 2016-12-06 Neul Ltd. Method and apparatus for estimating frequency errors
CN104641610B (zh) * 2012-05-11 2017-12-22 华为技术有限公司 用于估计频率误差的方法和装置

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