CN101227448B - Time synchronism apparatus, method and receiver using mobile window channel estimation - Google Patents
Time synchronism apparatus, method and receiver using mobile window channel estimation Download PDFInfo
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- CN101227448B CN101227448B CN2008100804765A CN200810080476A CN101227448B CN 101227448 B CN101227448 B CN 101227448B CN 2008100804765 A CN2008100804765 A CN 2008100804765A CN 200810080476 A CN200810080476 A CN 200810080476A CN 101227448 B CN101227448 B CN 101227448B
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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
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- 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
- H04L25/03821—Inter-carrier interference cancellation [ICI]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
- H04L27/26524—Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
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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
- H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
- H04L27/2691—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation involving interference determination or cancellation
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Abstract
The invention discloses a time synchrony method of mobile window channel estimation, which can synchronize the channel estimation and the timing, and is suitable to the continuous channel estimations in order to avoid the inference among carrier wave which is caused by Doppler phenomenon. The key points of the method lie in that a plurality of orthogonal frequency division multiplexing code elements which are adjacent in the window are ensured to have the same timing regulation through adopting the method of the mobile window, thereby obtaining accurate channel response. Thus, each orthogonal frequency division multiplexing code element can obtain a channel response which can avoid the inference among carrier wave which is caused by the Doppler phenomenon, thereby increasing the property of a receiver under the condition of high-speed movement.
Description
Technical field
The invention relates to a kind of time synchronism apparatus, method and receiver of channel estimating, and particularly relevant for a kind of time synchronism apparatus, method and receiver that uses the mobile window channel estimating.
Background technology
In many wireless telecommunication systems, the orthogonal frequency division multiplex (MUX) is a kind of multi-carrier modulation method of knowing.Similarly be at ground digital television broadcast (Digital Video Broadcasting-Terrestrial, DVB-T), handheld digital television broadcasting (Digital Video Broadcasting-Handheld, DVB-H) etc. in the system, all be to use the orthogonal frequency division multiplex (MUX).
Use orthogonal frequency division multiplex's receiver, before rectification, the frequency response that must know channel earlier why, this is the function of channel estimating (Channel Estimation).
The method of channel estimating can be explained by Fig. 1 traditionally.(Orthogonal Frequency Division Modulation, OFDM) code element is divided into a window in per 4 OFDMs modulation among Fig. 1.At first, receiver goes out to be made as time of delay (Delay Time) n first time of delay by first window calculation
ε 0Receiver again by second window calculate be made as time of delay second time of delay n
ε 1And can be earlier when calculating the time of delay of the 3rd window with first time of delay n
ε 0Count, see again need to increase what the 3rd time of delay n
ε 2, promptly the time of delay of the 3rd window be first time of delay n
ε 0Add the 3rd time of delay n
ε 2In the same manner, when calculating the time of delay of the 4th window, can earlier be counted second time of delay, see again need to increase what the 4th time of delay n
ε 3, promptly the time of delay of four-light mouth be second time of delay n
ε 1Add the 4th time of delay n
ε 3In like manner, can earlier first time of delay and the 3rd time of delay be counted during time of delay of calculating the 5th window, see again need increase what the 5th time of delay n
ε 4, promptly the time of delay of the 5th window be first time of delay n
ε 0Add the 3rd time of delay n
ε 2Add the 5th time of delay n
ε 4Can earlier second time of delay and the 4th time of delay be counted during time of delay of calculating the 6th window, see again need increase what the 6th time of delay n
ε 5, promptly the time of delay of the 6th window be second time of delay n
ε 1Add the 4th time of delay n
ε 3Add the 6th time of delay n
ε 5Time of delay of window afterwards, by that analogy.
But the mode of this kind computing relay time is that the hypothesis channel is under the static state, just to have way to calculate time of delay.For example the channel that uses of system such as ground digital television broadcast is static, can use the method.But the channel as the handheld digital television broadcasting is dynamic, and the method is then inapplicable.And the channel transfer functions of the method (Channel transfer function) is discontinuous, and is also inapplicable in the handheld digital television broadcasting.
Still need one under dynamic channel, can eliminate Doppler (Doppler) inter-carrier interference that effect produced (Inter-Carrier Interference, channel estimating mode ICI).
Summary of the invention
The invention provides a kind ofly under dynamic channel, the channel estimating mode that can eliminate the inter-carrier interference that Doppler effect produces is at method for synchronizing time, time synchronism apparatus and receiver that a kind of mobile window (sliding window) channel estimating is provided.
The present invention proposes a kind of method for synchronizing time that is used for ofdm system mobile window channel estimating, and comprising provides the channel window, moves this channel window in regular turn; Adjust the phase place of most OFDM code elements in this channel window according to channel response last time, to produce most OFDM code elements; The present channel response of those OFDM code elements in present this channel window of estimation obtains present phase place trim values according to this present channel response; Obtain the shift time index value according to this present channel response, do fast fourier transform windows and regularly adjust; And the phase place of adjusting those OFDM code elements in this channel window according to this present phase place trim values.
The present invention proposes a kind of time synchronism apparatus of mobile window channel estimating, this device comprises the mobile window channel estimation circuit, in order to this channel window being provided and moving this channel window, and the estimation present channel response of most OFDM code elements in this channel window at present; The index value calculator calculates the shift time index value according to this present channel response; Accumulator is coupled to this index value calculator, in order to this shift time index value that adds up to obtain accumulated value; The time migration compensator is coupled to this accumulator, and the fractional part of output accumulated value is used for phase-adjusting circuit those first OFDM code elements are done the phase place adjustment of fractional part, and exports the integer part of this accumulated value; Foourier transform processor is coupled to this time migration compensator, according to the integer part of this accumulated value those first OFDM code elements is made fast fourier transform windows regularly; And phase-adjusting circuit, be coupled to this mobile window channel estimation circuit, adjust the phase place of those OFDM code elements in this channel window according to channel estimation value last time, and obtain present phase place trim values, and will this present phase place trim values adjust the phase place of those OFDM code elements in this channel window according to this present channel response.
The present invention also proposes a kind of receiver with mobile window channel estimating, and this receiver comprises: the receiver front end circuit, and in order to will receiving most OFDM code elements, and those OFDM code elements that will receive are made the signal processing of front end; Fast fourier transformation apparatus is coupled to this receiver front end circuit, makes fast fourier transform in order to those OFDM code elements that this receiver front end circuit is exported; The time synchronism apparatus of mobile window channel estimating is coupled to this fast fourier transformation apparatus, in order to the mobile channel window; Adjust the phase place of most OFDM code elements in this channel window according to channel response last time, to produce most the first OFDM code elements; The present channel response of those the first OFDM code elements in present this channel window of estimation obtains present phase place trim values according to this present channel response; And adjust the phase place of those the first OFDM code elements in this channel window according to this present phase place trim values, and obtain the shift time index value according to this present channel response, do fast fourier transform windows and regularly adjust; And the receiver back-end circuit, be coupled to the time synchronism apparatus of this mobile window channel estimating, make the signal processing of rear end in order to those OFDM code elements that the time synchronism apparatus of mobile window channel estimating is exported.
It should be noted that the method for embodiments of the invention, so each OFDM code element all can obtain a channel response and timing is adjusted, thereby can improve the performance of the receiver under the high-speed mobile situation because of employing mobile channel window.Because high-speed mobile can cause Doppler's phenomenon, this Doppler's phenomenon can cause the problem of inter-carrier interference, so can adopt the algorithm that disturbs between suppressed carrier simultaneously.In addition on the one hand, the method has also reduced the Data Detection delay and has reduced the storage area.
For above and other objects of the present invention, feature and advantage can be become apparent, preferred embodiment cited below particularly, and cooperate appended graphicly, be described in detail below.
Description of drawings
Fig. 1 is the schematic diagram of channel estimation methods traditionally.
Fig. 2 A is the schematic diagram of the method for synchronizing time of the use mobile window channel estimating that provides according to the embodiment of the invention.
Fig. 2 B is the method flow diagram of the method for synchronizing time of the use mobile window channel estimating that provides according to the embodiment of the invention.
Fig. 3 is the system block diagrams of the time synchronism apparatus 300 of the mobile window channel estimating that provides according to the embodiment of the invention.
Fig. 4 is the system block diagrams of the receiver with mobile window channel estimating 400 that provides according to the embodiment of the invention.
Embodiment
For the easier quilt of the present invention is understood, below will cooperate diagram and embodiment that time synchronism apparatus, method and the receiver of use mobile window channel estimating provided by the present invention are described.
Fig. 2 A is the schematic diagram of the method for synchronizing time of the use mobile window channel estimating that provides of the embodiment of the invention.The method provides channel window 201, and the length of channel window 201 is made as 4, and promptly channel window 201 contains 4 OFDM code elements, yet the execution mode of these channel window 201 length is not in order to limit the present invention.Channel window 201 position at the beginning is at d0, and the OFDM code element that this moment, the channel length of window was comprised comprises: OFDM code element 0, OFDM code element 1, OFDM code element 2 and OFDM code element 3.Channel window 201 can be adjusted the phase place of OFDM code element 0 in the channel window 201, OFDM code element 1, OFDM code element 2 and OFDM code element 3 according to channel response last time, to produce 4 OFDM code elements of adjusting through phase places, promptly the OFDM code element of adjusting through phase place 0, the OFDM code element of adjusting through phase place 1, through phase place OFDM code element of adjusting 2 and the OFDM code element of adjusting through phase place 3.Then, estimate the present channel response of the OFDM code elements 0 of present channel window 201 interior process phase places adjustment, the OFDM code element 1 that the process phase place is adjusted, the OFDM code element 2 of process phase place adjustment and the OFDM code element 3 that the process phase place is adjusted etc., according to this present channel response, obtain present phase place trim values and shift time index value.Wherein, present phase place trim values is sent out phase place at last and has been adjusted the OFDM code element 0 that finishes in order to the phase place of the OFDM code elements 0 of adjusting the 201 interior process phase places adjustment of channel window, the OFDM code element 1 that the process phase place is adjusted, the OFDM code element 2 of process phase place adjustment and the OFDM code element 3 that the process phase place is adjusted etc.
The mobile channel position of window is to d1 then, and the OFDM code element that this moment, the channel length of window was comprised comprises: OFDM code element 1, OFDM code element 2, OFDM code element 3 and OFDM code element 4.Channel window 201 can be adjusted the phase place of OFDM code element 1 in the channel window 201, OFDM code element 2, OFDM code element 3 and OFDM code element 4 according to channel response last time, to produce 4 OFDM code elements of adjusting through phase places, promptly the OFDM code element of adjusting through phase place 1, the OFDM code element of adjusting through phase place 2, through phase place OFDM code element of adjusting 3 and the OFDM code element of adjusting through phase place 4.Then, estimate the present channel response of the OFDM code elements 1 of present channel window 201 interior process phase places adjustment, the OFDM code element 2 that the process phase place is adjusted, the OFDM code element 3 of process phase place adjustment and the OFDM code element 4 that the process phase place is adjusted etc., according to this present channel response, obtain present phase place trim values and shift time index value.Wherein, present phase place trim values is sent out phase place at last and has been adjusted the OFDM code element 1 that finishes in order to the phase place of the OFDM code elements 1 of adjusting the 201 interior process phase places adjustment of channel window, the OFDM code element 2 that the process phase place is adjusted, the OFDM code element 3 of process phase place adjustment and the OFDM code element 4 that the process phase place is adjusted etc.
By that analogy, in regular turn mobile channel window 201 to position d2, d3 ..., dn, repeat above method, send out individually phase place adjusted the OFDM code element 2, the phase place that finish adjusted the OFDM code element 3 that finishes ..., phase place adjusted the OFDM code element n that finishes.So method can obtain the channel response on the up-to-date code element continuously, and utilize channel response last time to adjust channel window 201 interior 4 OFDM code elements producing four OFDM code elements of adjusting through phase places, and utilize present channel response to adjust channel window 201 interior 4 OFDM code elements of adjusting through phase place.
It should be noted that the method for present embodiment, so each OFDM code element all can obtain a channel response and timing is adjusted, thereby can improve the performance of the receiver under the high-speed mobile situation because of employing mobile channel window 201.Because high-speed mobile can cause Doppler's phenomenon, this Doppler's phenomenon can cause the problem of inter-carrier interference, so can adopt the algorithm that disturbs between suppressed carrier simultaneously.In addition on the one hand, the method has also reduced the Data Detection delay and has reduced the storage area.
In addition, according to the shift time index value that present channel response obtained, be regularly to adjust (timing adjust) in order to do fourier transform windows.The method of mobile channel window 201, make each OFDM code element experience different window timing adjustment, so the phase place fine setting that should be aided with corresponding channel window 201 interior 4 OFDM code elements responds thereby guarantee to obtain correct continuous channel to guarantee that adjacent 4 OFDM code elements have identical window timing adjustment in the window.
And do mode that fourier transform windows regularly adjusts according to the shift time index value is when at every turn in regular turn during mobile channel window 201, and the shift time index value that can add up in regular turn is to produce accumulated value.At last, according to this accumulated value fourier transform windows is done regularly adjustment again.
In sum, can be organized into method flow diagram shown in Fig. 2 B.The method may further comprise the steps: step S210 provides a channel window that can comprise the OFDM code element, and sets the length of channel window.Step S220 is the mobile channel window in regular turn, makes the channel window contain the up-to-date OFDM code element of the length of channel window.Step S230 basis is channel response last time, adjusts the phase place of up-to-date OFDM code element in the channel window.Step S240 estimates present channel response according to the OFDM code element of adjusting through phase place.Step S250 produces phase adjustment value and shift time index value according to present channel response.The step S251 shift time index value that adds up in regular turn to produce accumulated value, is done regularly fourier transform windows according to accumulated value and to be adjusted.Step S260 adjusts the OFDM code element in the present channel window according to the phase adjustment value that last step S250 produces, again with first code element output in the channel window.Step S270 judges whether that up-to-date OFDM code element is still arranged, if also have up-to-date OFDM code element then jump to step S220, repeats above-mentioned steps flow chart, if do not have up-to-date OFDM code element then finish the method.
Fig. 3 is the system block diagrams of the time synchronism apparatus 300 of the mobile window channel estimating that provides of the embodiment of the invention.This device 300 comprises mobile window channel estimation circuit 301 and phase-adjusting circuit 302, and phase-adjusting circuit 302 is coupled to mobile window channel estimation circuit 301.Wherein this mobile window channel estimation circuit 301 provides channel window and mobile channel window, and the present channel response of the OFDM code element of a plurality of process phase places adjustment in present this channel window of estimation.The length of channel window is made as 4, and promptly the channel window contains 4 OFDM code elements, yet the execution mode of this channel length of window is not in order to limit the present invention.
Phase-adjusting circuit 302 is adjusted the phase place of a plurality of OFDM code elements in the channel window according to channel response last time, and obtain present phase place trim values, and use present phase place trim values to adjust the phase places of a plurality of OFDM code elements of adjusting through phase places in the channel window according to present channel response.And phase-adjusting circuit 302 is described as the method embodiment of Fig. 2 A with the method for operation of mobile window channel estimation circuit 301, just seldom gives unnecessary details at this.
In addition, index value calculator 303, accumulator 304, time migration compensator 305 and fast fourier transformer 306 have also been comprised in the device 300.Index value calculator 303 is coupled to mobile window channel estimation circuit 301, according to mobile window channel estimation circuit 301 estimate the present channel response that and calculate the shift time index value.Accumulator 304 is coupled to index value calculator 303, in order to the shift time index value that adds up to obtain accumulated value.Time migration compensator 305 is coupled to accumulator 304, and time migration compensator 305 receives accumulated value, and the integer part and the fractional part of output accumulated value.Fast fourier transformer 306 is coupled to time migration compensator 305, according to the integer part of accumulated value 4 OFDM code elements through the phase place adjustment in the present channel window is made fourier transform windows and regularly adjusts.The fractional part of accumulated value then is sent to phase-adjusting circuit 302, and phase-adjusting circuit 302 is done the phase place adjustment according to the fractional part of accumulated value to four OFDM code elements through the phase place adjustment.Wherein accumulated value can also be whole accumulated value, yet the execution mode of this accumulated value is not in order to limit the present invention.
It should be noted that the method for present embodiment, so each OFDM code element all can obtain a channel response and timing is adjusted, thereby can improve the receiver performance under the high-speed mobile situation because of employing mobile channel window.Because high-speed mobile can cause Doppler's phenomenon, this Doppler's phenomenon can cause the problem of inter-carrier interference, so can adopt the algorithm that disturbs between suppressed carrier simultaneously.In addition on the one hand, the method has also reduced the Data Detection delay and has reduced the storage area.
In addition, the method of mobile channel window, make each code element experience different window timing adjustment, regularly adjust to guarantee that adjacent 4 OFDM code elements have uniform window in the channel window so should be aided with the phase place fine setting of 4 OFDM code elements in the corresponding channel window, thereby guarantee to obtain correct continuous channel response.
Fig. 4 is the system block diagrams of the receiver with mobile window channel estimating 400 that provides of the embodiment of the invention.This receiver 400 comprises the time synchronism apparatus 403 and receiver back-end circuit 404 of receiver front end circuit 401, fast fourier transformation apparatus 402, mobile window channel estimating.
Receiver front end circuit 401, in order to receiving most OFDM code elements, and most the OFDM code elements that will receive are made the signal processing of front end.
Fast fourier transform device 402 is coupled to receiver front end circuit 401, does fast fourier transform in order to most the OFDM code elements that receiver front end circuit 401 is exported.
The time synchronism apparatus 403 of mobile window channel estimating is coupled to fast fourier transformation apparatus 402, and this device 403 comprises mobile window channel estimation circuit and phase-adjusting circuit.Phase-adjusting circuit is coupled to the mobile window channel estimation circuit.Wherein this mobile window channel estimation circuit provides channel window and mobile channel window, and the present channel response of the OFDM code element of a plurality of process phase places adjustment in present this channel window of estimation.The length of channel window is made as 4, and promptly the channel window contains 4 OFDM code elements, yet the execution mode of this channel length of window is not in order to limit the present invention.
Phase-adjusting circuit is adjusted the phase place of a plurality of OFDM code elements in this channel window according to channel estimation value last time, and obtain present phase place trim values, and use present phase place trim values to adjust the phase places of a plurality of OFDM code elements of adjusting through phase places in the channel window according to this present channel response.And the method for operation of phase-adjusting circuit and mobile window channel estimation circuit is described as the method embodiment of Fig. 2 A, just seldom gives unnecessary details at this.
In addition, index value calculator, accumulator, time migration compensator and fast fourier transformer have also been comprised in the time synchronism apparatus 403 of mobile window channel estimating.The index value calculator is coupled to the mobile window channel estimation circuit, estimates the present channel response that according to the mobile window channel estimation circuit and calculates the shift time index value.Accumulator is coupled to the index value calculator, in order to the shift time index value that adds up to obtain accumulated value.The time migration compensator is coupled to accumulator, and the time migration compensator receives accumulated value, and the integer part and the fractional part of output accumulated value.Fast fourier transformer is coupled to the time migration compensator, according to the integer part of accumulated value 4 OFDM code elements through the phase place adjustment in the present channel window is made fourier transform windows and regularly adjusts.The fractional part of accumulated value then is sent to phase-adjusting circuit, makes phase-adjusting circuit do the phase place adjustment according to the fractional part of accumulated value to four OFDM code elements through the phase place adjustment.Wherein accumulated value can also be whole accumulated value, yet the execution mode of this accumulated value is not in order to limit the present invention.
It should be noted that the method for present embodiment, so each OFDM code element all can obtain a channel response and timing is adjusted, thereby can improve the receiver performance under the high-speed mobile situation because of employing mobile channel window.Because high-speed mobile can cause Doppler's phenomenon, this Doppler's phenomenon can cause the problem of inter-carrier interference, so can adopt the algorithm that disturbs between suppressed carrier simultaneously.In addition on the one hand, the method has also reduced the Data Detection delay and has reduced the storage area.
In addition, the method of mobile channel window, make each code element experience different window timing adjustment, regularly adjust to guarantee that adjacent 4 OFDM code elements have uniform window in the channel window so should be aided with the phase place fine setting of 4 OFDM code elements in the corresponding channel window, thereby guarantee to obtain correct continuous channel response.
And receiver back-end circuit 404, be coupled to mobile window channel estimating time synchronism apparatus 403, make the signal processing of rear end in order to the OFDM code element of individual elapsed time of the majority that the time synchronism apparatus 403 of mobile window channel estimating is exported and phase compensation.
Moreover, receiver 400 with mobile window channel estimating also comprises: carrier frequency and sample frequency are followed the trail of circuit 405, be coupled to receiver front end circuit 401 and fast fourier transformation apparatus 402, in order to receive the output of fast fourier transform, to obtain carrier frequency and sample frequency, send carrier frequency and sample frequency to receiver front end circuit 401 again.
In sum, method for synchronizing time in the mobile window channel estimating that embodiments of the invention provided, each OFDM code element can obtain a channel response, not only can be used for the receiver under the inactive state, even on the receiver of fast moving, use, can also overcome because the inter-carrier interference problem that doppler phenomenon caused.
Though the present invention discloses as above with embodiment; right its is not in order to qualification the present invention, any those skilled in the art, without departing from the spirit and scope of the present invention; when can doing a little change and retouching, so protection scope of the present invention is as the criterion when looking appended the claim scope person of defining.
Claims (7)
1. method for synchronizing time that is used for ofdm system mobile window channel estimating comprises:
The mobile channel window;
Adjust the phase place of most OFDM code elements in this channel window according to channel response last time, to produce most the first OFDM code elements;
The present channel response of those the first OFDM code elements in present this channel window of estimation obtains present phase place trim values according to this present channel response;
Obtain the shift time index value according to this present channel response, do fast fourier transform windows and regularly adjust; And
Adjust the phase place of those the first OFDM code elements in this channel window according to this present phase place trim values.
2. method for synchronizing time according to claim 1, wherein do fast fourier transform windows and regularly adjust and may further comprise the steps according to this shift time index value:
This shift time index value that adds up in regular turn is to produce accumulated value; And
According to this accumulated value fast fourier transform windows is done regularly adjustment.
3. time synchronism apparatus that is used for ofdm system mobile window channel estimating, wherein this device comprises:
The mobile window channel estimation circuit, in order to the mobile channel window, and the present channel response of most the first OFDM code elements in present this channel window of estimation;
The index value calculator calculates the shift time index value according to this present channel response;
Accumulator is coupled to this index value calculator, in order to this shift time index value that adds up to obtain accumulated value;
The time migration compensator is coupled to this accumulator, and the fractional part of output accumulated value is used for phase-adjusting circuit those first OFDM code elements are done the phase place adjustment of fractional part, and exports the integer part of this accumulated value;
Foourier transform processor is coupled to this time migration compensator, according to the integer part of this accumulated value those first OFDM code elements is made fast fourier transform windows regularly; And
Phase-adjusting circuit, be coupled to this mobile window channel estimation circuit, adjust the phase place of those OFDM code elements in this channel window according to channel estimation value last time, and obtain present phase place trim values, and will this present phase place trim values adjust the phase place of those the first OFDM code elements in this channel window according to this present channel response.
4. one kind is used for the receiver that ofdm system has the mobile window channel estimating, comprising:
The receiver front end circuit, in order to will receiving most OFDM code elements, and those OFDM code elements that will receive are made the signal processing of front end;
Fast fourier transformation apparatus is coupled to this receiver front end circuit, makes fast fourier transform in order to those OFDM code elements that this receiver front end circuit is exported;
The time synchronism apparatus of mobile window channel estimating is coupled to this fast fourier transformation apparatus, in order to the mobile channel window; Adjust the phase place of most OFDM code elements in this channel window according to channel response last time, to produce most the first OFDM code elements; The present channel response of those the first OFDM code elements in present this channel window of estimation obtains present phase place trim values according to this present channel response; Obtain the shift time index value according to this present channel response, do fast fourier transform windows and regularly adjust; And the phase place of adjusting those the first OFDM code elements in this channel window according to this present phase place trim values; And
The receiver back-end circuit is coupled to the time synchronism apparatus of this mobile window channel estimating, makes the signal processing of rear end in order to those OFDM code elements that the time synchronism apparatus of mobile window channel estimating is exported.
5. receiver according to claim 4, wherein the time synchronism apparatus of this mobile window channel estimating comprises:
The mobile window channel estimation circuit, in order to mobile this channel window, and this present channel response of those OFDM code elements in present this channel window of estimation; And
Phase-adjusting circuit, be coupled to this mobile window channel estimation circuit, according to this last time channel estimation value adjust the phase place of those OFDM code elements in this channel window, and obtain this present phase place trim values, and will this present phase place trim values adjust the phase place of those interior OFDM code elements of this channel window according to this present channel response.
6. receiver according to claim 5, wherein the time synchronism apparatus of this mobile window channel estimating also comprises:
The index value calculator calculates the shift time index value according to this present channel response;
Accumulator is coupled to this index value calculator, in order to this shift time index value that adds up to obtain accumulated value;
The time migration compensator is coupled to this accumulator, and the output accumulated value gets fractional part, is used for this phase-adjusting circuit those OFDM code elements are done the phase place adjustment of fractional part, and export the integer part of this accumulated value; And
Foourier transform processor is coupled to this time migration compensator, according to the integer part of this accumulated value those OFDM code elements is made fast fourier transform windows regularly.
7. receiver according to claim 5, this receiver also comprises:
Carrier frequency and sample frequency are followed the trail of circuit, are coupled to this receiver front end circuit and this fast fourier transformation apparatus, in order to receive the output of this fast fourier transform, to obtain carrier frequency and sample frequency.
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| CN2008100804765A CN101227448B (en) | 2008-02-19 | 2008-02-19 | Time synchronism apparatus, method and receiver using mobile window channel estimation |
| KR1020080129284A KR100981066B1 (en) | 2008-02-19 | 2008-12-18 | Synchronization method and apparatus using sliding window for channel estimation |
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| CN2008100804765A CN101227448B (en) | 2008-02-19 | 2008-02-19 | Time synchronism apparatus, method and receiver using mobile window channel estimation |
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| CN102271102B (en) * | 2010-06-03 | 2014-09-10 | 大唐移动通信设备有限公司 | Channel estimating method and equipment based on sliding window |
| CN106027116B (en) * | 2016-07-07 | 2018-08-31 | 哈尔滨工程大学 | A kind of mobile underwater sound communication Doppler coefficient method of estimation based on chirp signals |
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| CN101227448A (en) | 2008-07-23 |
| KR100981066B1 (en) | 2010-09-08 |
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