TWI361576B - Synchronization method and apparatus using sliding window for channel estimation - Google Patents

Description

1361576 Kawasaki said that the month is replacing page _ 100-8-22 IX. Description of the invention: [Technical field of the invention] The present invention relates to a time synchronization device, method and reception H for channel estimation, and the system is A time synchronization device, method and receiver for estimating the axis of the window. [Prior Art] On many wireless communication systems, orthogonal frequency division multiplexing is a well-known multi-carrier modulation method. For example, in terrestrial digital TV broadcasts, Bn^asting-Terrestr^DVB-T), handheld digital TV broadcast (4), Video Broadcasting-Handheld, DVB-Η, etc., all use orthogonal frequency division. work. With orthogonal frequency division multiplexing receivers, the frequency response of the channel must be known before demodulation, which is the function of Channel Estimation. The traditional method of channel estimation can be explained by Figure 1. In Figure 1, each of the four orthogonal carrier frequency division modulation (OFDM) symbols is divided into a window. First, the receiver calculates the delay time from the first window to be the first delay time (Dday Time) ns0. The receiver then calculates the delay time from the second window as the second delay time ηε1 〇, and when calculating the delay time of the third window, first calculates the first delay time ηε0, and then looks at how much the third needs to be increased. The delay time η ε 2 'that is, the delay time of the third window is the first delay time 仏. Plus the third delay time 仏2. Similarly, when calculating the delay time of the fourth window, the second delay time is first counted, and then the number of U years that need to be added is counted. The f-month correction replacement page - 100-8-22, the delay time ηε3', that is, the delay time of the fourth window is the second delay time ~ 1st of the fourth delay time η ε3. Similarly, when calculating the fifth window gorge delay time, the first delay time and the third delay time are counted, and then the fifth delay time, which is less, is required, that is, the delay time of the fifth window is the first: delay Time ηε. Adding the third delay time plus the fifth delay time difference, the delay time of the window will first count the second delay time and the fourth delay, and then see how much the sixth delay time needs to be increased ~ 5 The delay time of the sixth window is the second delay time hi plus the fourth delay time ~3 plus the sixth delay time η". The delay time of the window, and so on. But the way of calculating the delay time is assumed When the channel is stationary, there is a way to calculate the delay time. For example, the channel used by the system such as terrestrial digital TV broadcasting is still, so this method can be used. However, the channel like handheld digital TV broadcasting is dynamic, this method It does not apply. Moreover, the channel transfer function of this method is discontinuous and is not suitable for handheld digital TV broadcasting. Therefore, we need a Doppler effect in the dynamic channel. Channel estimation method of Inter-Carrier Interference (ICI) generated. SUMMARY OF THE INVENTION The present invention provides a dynamic channel Channel estimation method for eliminating inter-carrier interference generated by the Doppler effect provides a time synchronization method for channel estimation of a sliding window, a time synchronization device and a receiver. The present invention proposes a method for orthogonal carrier frequency division. Mobile view in the system 1361576

100-8-22 Sakizaki reversal correction replacement page

Window channel estimation = inter-synchronization method. First, a channel window is provided, and the channel window is sequentially moved; then, the phases of the plurality of positive-carrier frequency division symbols in the channel window are adjusted according to the previous channel response to generate a plurality of orthogonal carrier frequency symbols 70; Estimating the current channel response of the orthogonal carrier frequency division symbol in the current channel window, obtaining the current phase trimming value according to the current channel response, and adjusting the positive parent carrier points in the channel window according to the current phase trimming value. The phase of the frequency symbol. The present invention provides a mobile window channel estimation and time synchronization device that includes a mobile window channel estimation circuit and a phase adjustment circuit. The mobile window channel estimation circuit is used to provide a channel window and a moving channel window, and to estimate the current channel response of the orthogonal carrier frequency symbols in the current channel window. The phase adjustment circuit is coupled to the mobile channel window estimation circuit, and adjusts the phase of the orthogonal carrier frequency division symbols in the channel window according to the previous channel estimation value, and obtains the current phase fine adjustment value according to the current channel response, and The current phase trim value is adjusted to the phase of the positive-female carrier frequency-divided symbols in the channel window. . The present invention also provides a receiver with mobile window channel estimation. The receiver includes a receiver front end circuit, a fast Fourier transform device, a mobile window channel estimation and time synchronization device, and a receiver back end circuit receiver front end circuit. The plurality of orthogonal carrier frequency division symbols are received, and the received orthogonal carrier frequency division symbols are used as signal processing of the front end. The fast switching device is coupled to the front end circuit of the receiver for converting the orthogonal carrier frequency division symbols output by the receiver circuit to the fast Fourier transform. The mobile window channel estimation and time synchronization device is coupled to the fast Fourier 7 1361576 / ♦ zhouzhou correction replacement page __. J100-8-22 industry conversion device for providing a channel window, adjusting the channel window according to the current channel response And move the channel window in sequence. The receiver back-end circuit is coupled to the mobile window channel estimation and time synchronization device for performing signal processing of the orthogonal carrier frequency division symbols output by the time synchronization device of the mobile window channel estimation. It is worth noting that the embodiment of the present invention can improve the performance of the receiver under high-speed operation by adopting the method of moving the channel window, so that each channel of the orthogonal carrier frequency can obtain a channel response and timing adjustment. . At the same time, due to the phenomenon of Doppler caused by high-speed movement, this Doppler phenomenon will cause ICI problems, so the algorithm for suppressing ici can be used. On the other hand, this method also reduces data detection delay and reduces storage space. The above and other objects, features and advantages of the present invention will become more <RTIgt; [Embodiment] In order to make the present invention easier to understand, the time synchronizing apparatus, method and receiver using the mobile window channel estimation provided by the present invention will be described below with reference to the drawings and embodiments. 2A is a schematic diagram of a time synchronization method using mobile window channel estimation according to an embodiment of the present invention. This method provides that the length of the channel window 201' channel window 2〇1 is set to four, i.e., the channel window 201 contains four OFDM symbols. However, the implementation of the length of the channel window 201 is not intended to limit the present invention. Channel window 201 - the starting position is at d0, and this 1361576 / + Ή modified replacement page _ 100-8-22 includes the OFDM symbol 0 of the OFDM symbol 0, OFDM symbol OFDM symbol 2 and OFDM symbol 3. The channel window 201 adjusts the phases of the OFDM symbol 0, the OFDM symbol 1, the OFDM symbol 2, and the OFDM symbol 3 in the channel window 201 according to the previous channel response to generate four phase-adjusted OFDM symbols, that is, The phase-adjusted OFDM symbol 〇, the phase-adjusted OFDM symbol 1, the phase-adjusted OFDM symbol 2, and the phase-adjusted OFDM symbol 3. Then 'estimate the current channel of the phase-adjusted OFDM symbol 〇, the phase-adjusted 〇FDM symbol, the phase-adjusted OFDM symbol 2, and the phase-adjusted ofdm symbol 3 in the current channel window 2〇1 In response, according to the current channel response, the current phase trimming value and the offset time index value are obtained. The current phase trimming value is used to adjust the phase-adjusted 〇Fdm symbol 通道 in the channel window 201, the phase-adjusted OFDM symbol 1, the phase-adjusted 〇FDM symbol 2, and the phase-adjusted OFDM symbol 3 The phase of the equal phase finally transmits the OFDM symbol 相位 whose phase has been adjusted. Therefore, it should be noted that, after transmission through the wireless channel, the channel will affect the phase offset value (or phase difference value) of the orthogonal carrier (4) element transmitted by the transmitting end, and the phase fine adjustment The value is used to eliminate this effect = offset value. According to the current channel response, the current phase trimming value of Hi can be used to make any channel response to estimate the phase of the phase that needs to be eliminated. The value of the method, the giant hair, secretly stated above. In addition, the pure knowledge of the field should be able to be the father of the father, the division usually contains the preset known fixed length, 1361576 loo years qp month yvg correction replacement page 100-8-22 know the fixed amplitude and the known fixed phase A symbol (for example, an indicator) can be used to estimate the current channel response and obtain the amplitude response portion and phase response portion of the current channel response. From the phase response portion, it is estimated that the phase offset value caused by the channel for the orthogonal carrier frequency division symbol needs to be eliminated, and the phase trimming value can be estimated. Then, the position of the channel window is moved to dl. At this time, the OFDM symbol included in the channel window length includes: OFDM symbol 1, OFDM symbol 2, OFDM symbol 3, and OFDM symbol 4. The channel window 201 adjusts the phases of the OFDM symbol 1, the 〇fdm symbol 2, the OFDM symbol 3, and the OFDM symbol 4 in the channel window 201 according to the previous channel response to generate four.

The phase-adjusted OFDM symbols, that is, the phase-adjusted 〇FDM symbol 1, the phase-adjusted 0FDM symbol 2, the phase-adjusted OFDM symbol 3, and the phase-adjusted OFDM symbol 4. Next, the current channel response of the phase-adjusted OFDM symbol 丨, the phase-adjusted OFDM symbol 2, the phase-adjusted 〇FDM symbol 3, and the phase-adjusted 0FDM symbol 4 in the current channel window 201 is estimated. According to the current channel response, the current phase trimming value and the offset time index value are obtained. The current phase trimming value is used to adjust the phase-adjusted OFDM symbol 1 and the phase-adjusted 〇FDM symbol 2 in the channel window 2〇1.

The phase-adjusted OFDM symbol 3 and the phase-adjusted 〇fdM payer 4 are phased, and finally the ofdm symbol 1 whose phase has been adjusted is transmitted. By analogy, the channel window 2〇1 is moved to the positions d2, d3, and dn in sequence, and the above method is repeated, and the phase has been adjusted and the phase has been adjusted.

100-8-22 1361576 OFDM symbol 2, 〇fdM symbol 3 whose phase has been adjusted, and OFDM symbol η whose phase has been adjusted. Therefore, the method can continuously obtain the channel response on the latest symbol and use the previous channel response to adjust 4 OFDM symbols in the channel window 201 to generate four phase-adjusted OFDM symbols, and adjust the channel window 2 by using the current channel response. Four phase-adjusted OFDM symbols in 〇1. It should be noted that, in this embodiment, since the method of moving the channel window 2〇1 is adopted, a channel response and timing adjustment can be obtained for each OFDM symbol, thereby improving the performance of the receiver in the case of high-speed operation. At the same time, due to the phenomenon of Doppler caused by high-speed movement, the phenomenon of this D〇ppler will cause ία problem, so the algorithm for suppressing ICI can be adopted. On the one hand, this method also reduces the data detection delay and reduces the storage. In addition, the offset time index value obtained according to the current channel response is used for FFT window timing adjustment. The method of owing the period of time is such that each OFDM symbol undergoes a different window to be supplemented by the corresponding four OFDM symbols in the channel window 201 = fine-tuning to ensure that the adjacent four OFDM symbols in the window have The same view is adjusted to ensure correct continuous channel response. The FFT window timing adjustment is performed according to the offset time index value. Hi: When the channel window 201 is moved in the same order, the offset time window is sequentially added to perform the timing = the accumulated value. Finally, according to the accumulated value, the FFT is as described above, and can be organized into a flow chart of the method shown in FIG. 2B. 11 1361576 100-8-22

The method includes the following steps: Step S210 provides a channel window that can include 〇fDM symbols, and sets the length of the channel window. Step S220 sequentially moves the channel window so that the channel window contains the latest OFDM symbols of the length of the channel window. Step S230 adjusts the phase of the latest OFDM symbol in the channel window based on the previous channel response. Step S240 estimates the current channel response based on the phase adjusted OFDM symbols. Step S250 generates a phase trimming value and an offset time index value according to the current channel response. Step 251 sequentially accumulates the offset time index value to generate an accumulated value, and performs timing adjustment on the FFT window according to the accumulated value. Step S26: adjusting the OFDM symbol in the current channel window according to the phase trimming value generated in the previous step S250, and outputting the first symbol in the channel window. In step S27, it is judged whether there is still the latest OFDM symbol. If there is the latest 〇FDM symbol, the process jumps to step S220, and the above-mentioned step flow is repeated. If there is no newest OFDM symbol, the method ends. FIG. 3 is a system block diagram of a mobile window channel estimation and time synchronization apparatus 300 provided by an embodiment of the present invention. The device 3 includes a mobile window channel estimation circuit 301 and a phase adjustment circuit 3〇2, and the phase adjustment circuit 302 is coupled to the mobile window channel estimation circuit 3〇1. The mobile window pass 2 estimation circuit 301 provides a channel window and a moving channel window, and estimates the current channel response of the plurality of phase-adjusted symbols in the channel window. The length of the channel window is set to 4, i.e., the channel view window contains 4 〇FDM symbols. However, the implementation of the channel window length is not intended to limit the present invention. The phase adjustment circuit 302 adjusts the channel window according to the previous channel response 1361576

100-8 '22 j The phase of multiple OFDM symbols, and (iv) the current channel response 刖 phase trimming value, and use the current phase trimming value to adjust the phase of the 0 brain symbol of the channel. The operation method of the ancient and it-type apparent solid channel estimation circuit 3〇1 of the phase adjustment Ϊί is as described in the method of Fig. ί, and will not be described here. Λ In addition, the device 300 further includes a 丨 value calculator, an accumulation 枯 4 4 offset offset 4 〇 3 〇 5 and a fast Fourier converter 306. The cable calculator 303 is connected to the mobile window channel estimation circuit, and the current channel response estimated by the window channel estimation circuit 3〇1 calculates the offset time index value. The accumulator 304 engages the index value 3 3 3 丄 to accumulate the offset time index value to obtain the accumulated value. The time offset compensator 305 is connected to the accumulator 3〇4, and the time offset compensator 3〇5 receives the accumulated value and outputs the integer part and the fractional part of the accumulated value. The fast Fourier converter 306 is lightly connected to the time offset compensator 3〇5, and performs FFT view_timing adjustment on the four phase-adjusted 〇fdM pay elements in the witness channel window according to the accumulated value=t number#. The fractional part of the accumulated value is transferred to the ^-bit adjustment circuit 3〇2'. The phase adjustment circuit 3〇2 adjusts the phase adjustment of the four phase-adjusted OFDM symbols based on the fractional part of the accumulated value. The accumulated value may also be the entire accumulated value, however, the embodiment of the accumulated value is not intended to limit the present invention. It should be noted that this embodiment can improve the performance of the receiver in the case of high-speed operation by adopting the method of moving the channel window, so that each channel symbol and timing adjustment can be obtained for each OFDM symbol. At the same time, because of the speed of movement, it will cause Doppler's phenomenon. This Doppler phenomenon will be replaced by the 13th month. - 100-8-22 == Title: Yes: The algorithm for suppressing 1CI is adopted. In addition, moving H 1 ^ detects delays and reduces storage space. The same window method 'allows each symbol to undergo a phase of the F· symbol. The four symbols in the channel window have four adjacent (four) M-channel responses in the same window. _ The whole heart is guaranteed to be correctly continuous. The system block diagram of the mobile window channel is provided by the present invention. The receiver is fully equipped with a 4G2, mobile window channel, and 4G3 and time synchronization t are set to match the receiver back-end circuit. The receiver front end circuit 4〇1 is configured to receive a plurality of 0FDM symbols, and the (4) home touch FDM#it is used as a front end signal processing. The fast Fouriers device 4 is coupled to the receiver front end circuit 401 for performing a fast Fourier conversion on the majority of the 〇fdm symbols output by the receiver shovel circuit 401. The mobile window channel estimation and time synchronization device 4〇3 is coupled to the fast Fourier conversion device 4〇2, which includes a mobile window channel estimation circuit and a phase adjustment circuit. The phase adjustment circuit is coupled to the mobile channel estimation circuit. The mobile window channel estimation circuit provides a channel window and a moving channel window, and estimates the current channel response of a plurality of phase-adjusted 0FDM symbols in the channel window. The length of the channel window is set to 4', i.e., the channel window contains 4 OFDM symbols. However, the embodiment of the channel window length is not intended to limit the present invention. Year Correction Replacement Page 100-8-22 Only the eye position adjustment f road is adjusted according to the previous channel estimation value. (4) Channel window: Γ OFTM 7^ phase ' and according to the current channel response, the record is shun 'money Use the current phase (10) general channel window = the phase of the phase-adjusted 〇FDM symbol. The operation method of the phase adjustment, /, mobile window channel estimation circuit is as described in the embodiment of Fig. 2A, and will not be described here. In addition, the mobile window channel estimation and time synchronization device 403 further 3:=value::, accumulator, time offset compensator and fast-path calculator minus mobile window channel estimation electric two-action The current channel is estimated by the estimated channel estimation circuit = the offset time index value is calculated. The accumulator is lightly connected to the index value i offset time index value to obtain an accumulated value. Time offset compensation = lightly connected to the accumulator, time offset compensation ϋ receiving accumulated value, and output time gate: the whole = minute and fractional part, the speed Fourier (four) converter is lightly connected: the shift compensator 'according to the accumulation The integer part of the value is adjusted for the FFT window timing of the current channel window = 0FDM symbol of the target.

The circuit part transmits the phase adjustment circuit so that the phase adjustment ^ _ 2 and the fractional part of the value are applied to the four phase-adjusted OFDM: Ϊ = Γ. The accumulated value may also be the entire accumulated value, however, the accumulated value/real financial formula is not (4) limited to the present invention. The value means that the present embodiment can obtain a channel response and timing adjustment due to the use of the mobile channel window to obtain a channel response and timing adjustment to improve the receiver performance under high-speed operation. At the same time, the phenomenon that D_er is caused by the movement of the fan, the phenomenon of DGPPler will be 1361576 100-8-22, and the correction of the replacement page causes the ICI problem, so the algorithm for suppressing ICI can be used. On the other hand, this method is also reduced. The data detection delay and the storage space are reduced. In addition, the method of moving the channel window makes each symbol undergo different window timing adjustment, so it should be supplemented by the phase fine tuning of 4 OFDM symbols in the corresponding channel window. Ensure that the adjacent four symbols in the channel window have the same window timing adjustment, thereby ensuring a correct continuous channel response. The receiver back end circuit 404 is coupled to the mobile window channel estimation time synchronization device 403 for moving The plurality of elapsed time and phase compensated 〇fdm symbols output by the time channel synchronization device 403 are used for signal processing at the back end. Furthermore, the receiver 4 (8) with mobile window channel estimation further includes · carrier frequency and sampling The frequency tracking circuit 405 is connected to the receiver front end circuit 401 and the fast Fourier conversion device 4〇2 for receiving fast ^ The output of the business conversion is obtained to obtain the carrier frequency and the sampling frequency, and then the carrier frequency and the slaughter frequency are transmitted to the receiver front end circuit 4〇1. In summary, the mobile window channel estimation provided by the embodiment of the present invention is provided. The time synchronization method 'Each OFDM symbol can get a channel response' can not only be used by receivers in stationary state, even in fast-moving receivers, it can overcome the ICI problem caused by (d) D_er phenomenon. While the present invention has been described above by way of example, it is not intended to limit the invention, and the invention may be modified and modified in a manner that does not depart from the spirit and scope of the invention. Scope 1361576 __ / ♦ (4) Correction of replacement page... A _ 100-8-22 is subject to the definition of the patent application scope. [Simplified Schematic] Figure 1 is a schematic diagram of a conventional channel estimation method. A schematic diagram of a time synchronization method using mobile channel estimation according to an embodiment of the present invention. When the channel estimation is provided, the method is shown in FIG. 3 is a system block diagram of the mobile window channel estimation and time synchronization device 300 according to an embodiment of the present invention. A system block diagram of a receiver 400 with mobile track estimation is provided. [Description of main component symbols] 201: channel window 3〇0 · mobile window channel estimation and time synchronization device 3〇1 · mobile window channel estimation circuit 302: phase adjustment circuit 303 - index value calculator 304: accumulator 3 〇 5: time offset compensator 306: fast Fourier transform 400: receiver 402 with mobile window 401: receiver front end circuit channel estimation: Fast Fourier Conversion Device Mobile Window Channel Estimation Time Synchronization Device 17 1361576 /Outside 9 Correction Replacement Page 100-8-22 404: Receiver Backend Circuit 405: Carrier Frequency and Sampling Frequency Tracking Circuit S210~S270: Step Process

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Claims (1)

1361576 VIC07-0037 24998twf.doc/d X. Patent application scope: L A time synchronization method for mobile window channel estimation in orthogonal carrier frequency division system, including: moving a channel window; adjusting according to a previous channel response Phases of a plurality of positive parent carrier frequency division symbols in the channel window to generate a plurality of first orthogonal carrier frequency division symbols; estimating the first orthogonal carrier frequency division symbols in the current window window One of the current channel responses obtains a current phase trim value based on the current channel response; and adjusts the phase of the first positive parent carrier frequency bins in the channel window based on the current phase trim value. 2. The time synchronization method for mobile window channel estimation according to claim 1, further comprising: obtaining an offset time index value according to the current channel response, and performing fast Fourier transform window timing adjustment. 3. The time synchronization method for mobile window channel estimation according to claim 2, wherein the fast Fourier transform window timing adjustment according to the offset time index value comprises the following steps: sequentially accumulating the offset time Bowing a value to generate a cumulative value; and timing adjustment of the fast Four-conversion window according to the accumulated value. 4. A mobile window remote estimation and time synchronization device for use in an orthogonal carrier frequency division system, Including: 1361576 VIC07-0037 24998twf.doc/d window channel estimation circuit 'used to move a channel window' == the channel response of the carrier frequency division symbols in the channel; and the path, the root circuit' Lightly connect to the mobile channel window to estimate the electric volume of your eight bottles. The estimated value of one of the channels is adjusted to adjust the phase of the orthogonal prephase two = in the channel window and obtain the target according to the current channel response. ', and adjust the current phase trimming value to adjust the phase of the m-crossing carrier frequency bin in the channel window. And the conversion window channel estimation time value of the item is calculated according to the current channel response, and an offset-accumulator is lightly connected to the index value calculator to accumulate the partial time index value. Obtaining an accumulated value; - a time offset compensator, consuming the accumulator, and outputting the accumulated fractional value to allow the phase adjustment circuit to perform phase adjustment of the fractional part of the first orthogonal carrier frequency division symbol, and output An integer part of the accumulated value; a Fourier transform processor coupled to the time offset compensator, and performing fast Fourier transform on the first positive six-carrier frequency-divided symbol in the channel window according to the integer part of the accumulated value Window timing. 6. A receiver for mobile window channel estimation in an orthogonal carrier frequency division system, comprising: a receiver front end circuit for receiving a plurality of orthogonal carrier frequency division symbols and receiving The orthogonal carrier frequency division symbols are processed by the front end No. 2 VIC07-0037 24998 twf.doc/d; a 恍 立 立 立 转换 转换 转换 转换 转换 转换The circuit 'for fast Fu Liye conversion; the second positive parent carrier frequency division symbol m胄 通纽计 速速傅立业 conversion I set, according to the wire in the fast window; and according to the channel response adjustment one channel one receiving The back-end circuit of the device is coupled to the time synchronization I, and the mobile device is viewed from the 31-channel estimation and the second-order mobile window communication device, and the orthogonal carrier frequency division symbols are used. Signal processing at the back end. The mobile window-through device includes a mobile window channel estimation and a time synchronization-moving visual channel estimation circuit for moving the area window, as described in claim 6 of the patent application scope. The target channel response of the orthogonal carrier frequency division symbols in the channel window; and a phase adjustment circuit coupled to the mobile channel window estimation circuit, based on the previous channel estimation Adjusting the orthogonal frequency division symbol_ bits in the channel window, and obtaining the phase trimming value according to the current channel response, and adjusting the current phase trimming value to the positive in the channel window The phase of the carrier frequency division symbol. 8. The receiver with mobile window channel estimation according to claim 7, wherein the mobile window channel estimation and time synchronization device further comprises: VIC07-0037 24998twf.doc/d VIC07-0037 24998twf.doc /d an index value calculator time index value; calculate an offset accumulation thief according to the current channel response, and lightly connect to the current time index value to obtain a sizing calculator for accumulating the offset-time offset compensation Pulling the fractional part so that the phase machine f ^ is accumulating 11, outputting the accumulating value part of her light, the money orthogonal remainder (four) symbol is made small ^ to extract the integer part of the accumulated value; and aunt, 1 The leaf conversion processor is coupled to the time offset compensator, and the integer part of the root two-valued value is currently subjected to fast Fourier transform window timing for the orthogonal carrier frequency division symbols in the channel window. ^ 9' If you want to use the mobile window channel estimation receiver in the seventh item, it also includes: A - carrier frequency m sampling frequency tracking circuit, _ no fast Fu Liye conversion device in the receiver front-end circuit '(4) Receive the output of the fast Four-industry conversion to obtain - carrier frequency and - sampling frequency.