US20130142292A1 - Method and apparatus for estimating frequency - Google Patents
Method and apparatus for estimating frequency Download PDFInfo
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- US20130142292A1 US20130142292A1 US13/757,368 US201313757368A US2013142292A1 US 20130142292 A1 US20130142292 A1 US 20130142292A1 US 201313757368 A US201313757368 A US 201313757368A US 2013142292 A1 US2013142292 A1 US 2013142292A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
- H04B1/14—Automatic detuning arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
- H04B1/708—Parallel implementation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
- H04J11/0069—Cell search, i.e. determining cell identity [cell-ID]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J2200/00—Indexing scheme relating to tuning resonant circuits and selecting resonant circuits
- H03J2200/02—Algorithm used as input for AFC action alignment receiver
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/70735—Code identification
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0044—Control loops for carrier regulation
- H04L2027/0063—Elements of loops
- H04L2027/0065—Frequency error detectors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0083—Signalling arrangements
- H04L2027/0089—In-band signals
- H04L2027/0091—Continuous signals
Definitions
- This application relates to wireless communication and wireless devices. More particularly, the invention relates to initialization of a communication link between a base station (BS) and a user equipment (UE).
- BS base station
- UE user equipment
- a training sequence of known symbols is used by the receiver to estimate the transmitted signal.
- TDD time division duplex
- the midamble of a TDD frame conventionally contains the training sequence of symbols.
- the conventional cell search process consists of a Step 1 algorithm which processes a primary synchronization code (PSC) on the primary synchronization code channel (PSCH) for synchronization channel (SCH) location determination.
- a Step 2 algorithm processes the secondary synchronization codes (SSC) for code group determination and timeslot synchronization, and a Step 3 algorithm performs midamble processing.
- PSC primary synchronization code
- SSC secondary synchronization codes
- VCOs are commonly used at the end of an automatic frequency control (AFC) process to adjustably control the frequency of the receiver to achieve synchronization between a transmitter and a receiver.
- the input for the VCO is a control voltage signal, which is typically generated by a control circuit that processes the amplitude and phase of the received symbols.
- a common problem during an AFC process is the initial fluctuations resulting from a potentially significant frequency offset between the transmitter and the receiver.
- the filtered output preferably provides a voltage controlling a voltage controlled oscillator (VCO).
- VCO voltage controlled oscillator
- NCO numeric controlled oscillator
- FIG. 1 is a block diagram showing the phase rotation approach for start-up AFC.
- FIGS. 2A and 2B taken together, comprise a block diagram of the interaction between start-up AFC and algorithm Steps 1, 2 and 3 of cell search.
- FIG. 2 shows the manner in which FIGS. 2 a and 2 b are arranged to create a complete block diagram.
- FIG. 3 shows a process diagram for a PI filter.
- FIG. 1 is a block diagram of a start-up adaptive frequency control (AFC) 10 used to reduce the frequency offset between a base station (BS) and user equipment (UE) during initial cell search procedure.
- Start-up AFC uses a phase rotation approach, which is based on the correlations of two sequences with the primary synchronization code (PSC).
- PSC primary synchronization code
- the stored PSC sequence 12 is rotated in opposing directions at 14 , 14 a , 16 , 16 a to respectively determine correlations with the received sequence 18 at 20 and 22 .
- the absolute values (a and b) are obtained at 24 and 26 and to obtain the value
- phase rotation at ⁇ 3 kHz alternatively can be replaced by a conjugate of a rotated PSC sequence at 3 kHz since the PSC sequence can only have values of (1+j) and ( ⁇ 1 ⁇ j).
- start-up AFC reduces the frequency offset from 6 kHz to less than 2 kHz in the least number of iterations.
- Table 1 shows a particular advantage of frequency correction which is an increase in allowable integrations. The number of integrations is limited, however, due to chip slip. The chip-slip upper boundary is 0.5 Tc since the maximum correlation is generated one sample later for a method utilizing twice the chip rate sampling. Table 1 summarizes the allowable number of integrations as frequency offset is reduced.
- Table 2 provides information on performance degradation for a coherent combining technique in the presence of carrier frequency offset.
- the start-up AFC procedure includes a mechanism to realign the primary synchronization code (PSC) position that may shift during correction.
- the Step 1 procedure can be run to eliminate the need for the mechanism while the start-up AFC algorithm is running.
- the Step 1 procedure updates the peak location every 4 th frame.
- FIG. 2 depicts the parallel processing relationship among start-up AFC and Steps 1, 2 and 3 of cell searching. Of particular concern is the relationship between Step 1 and start-up AFC. Since Step 1 works in parallel with the startup AFC, there is no need for a code tracker circuit to follow a given path. Each time Step 1 updates an output that is based on the largest detected value, start-up AFC uses the new peak location to estimate the new frequency offset.
- the frequency estimator block (FEB) 31 of the start-up AFC comprises a Sequence Locator and Splitter 32 , frequency estimators 34 - 38 , a proportional plus integral (PI) filter 42 , and a voltage controlled oscillator (VCO) or numeric controlled oscillator (NCO) 46 coupled to PI filter 42 through the sign flop 44 .
- the input 32 a to the Sequence Locator and Splitter 32 includes the PSC peak location chip-offset provided by Step 1.
- Start up AFC 30 is an open loop gain control block that steps through pre-defined gain levels in order to set proper input power level before digitizing the input.
- the main input to both Step 1 and the Sequence Locator and Splitter 32 is sampled at twice the chip rate with a length of 76,800 complex elements. Since the chip-offset points to the peak location, the beginning of the PSC is 511 samples before the chip-offset.
- the outputs of the Sequence Locator and Splitter 32 are generated by the following general equation:
- Locator and Splitter 32 in the example given in FIG. 2 is a PSC locator, it should be understood the same approach can be used with any received sequences other than PSC.
- the input samples to the Sequence Locator and Splitter are taken at twice the chip rate.
- the frequency estimators 34 , 36 and 38 each receive one of the three inputs provided by Equations (2)-(4).
- the frequency estimators estimate a different frequency offset, summed at 40, for each input sequence in accordance with FIG. 1 .
- the frequency offset, summed at 40 is the summation of early, punctual and late estimates.
- the sum of the estimates is passed through a proportional plus integral (PI) filter 42 with coefficients alpha and beta, respectively as shown in detail in FIG. 3 .
- the PI filter bandwidth has two settings. Initially, alpha and beta are preferably 1 ⁇ 2 and 1/256, respectively as shown in detail in FIG. 3 .
- FIG. 3 depicts such a PI filter structure 42 .
- the preferable settings for coefficients alpha and beta are summarized in Table 3. However, other filters may be substituted for the PI filter.
- the startup AFC completes at least ten (10) iterations
- the current output to the VCO is within ⁇ 1 kHz of the absolute value of the average of the second half.
- NCO numerically controlled oscillator
- the Step 1 FLAG 61 from controller 60 is set when a sequence is detected.
- the FEB 31 runs when the controller 60 provides an enable condition to FEB 31 at 62. Since the peak locations shift left or right in time, the Step 1 algorithm is run constantly.
- the start-up AFC reduces the frequency offset to about 2 kHz in many cases, which provides considerable enhancement to the Step 2 performance.
- PSC processing block 66 correlates against the primary synchronization code in (synchronization channel) (SCH) over frames.
- SCH primary synchronization code in (synchronization channel)
- SSC extractor block 68 utilizes the SCH location and extracts only the SCH portion, which is then passed to SSC processing block 70 .
- SSC processing block 70 correlates against the secondary synchronization code in synchronization channel over SCH.
- Midamble Extractor block 72 utilizes the SCH location and SSC processing results and extracts the midamble portion to pass to midamble processing block 74 .
- Midamble processing block 74 correlates against possible midambles given by SSC processing and picks the one with the highest energy.
- Periodic Cell Search block 76 performs a process which constantly searches for the best base station for the given period.
- Controller 60 coordinates among stages to synchronize to a base station.
- Layer 1 Controller 80 coordinates all layer 1 related hardware and software in order to maintain proper operation in the receiver.
Abstract
A method and apparatus for use in connection with wireless communication to adjust the frequency of an oscillator to synchronize with a received signal by correlating a synchronization code channel with training sequences to estimate relative offsets which are employed to estimate an error, which is then filtered. The filtered output preferably provides a voltage controlling a voltage controlled oscillator (VCO). The same technique may be employed to control a numeric controlled oscillator (NCO).
Description
- This application is a continuation of U.S. patent application Ser. No. 13/438,595, filed Apr. 3, 2012, which is a continuation of U.S. patent application Ser. No. 12/185,361, filed Aug. 4, 2008, now U.S. Pat. No. 8,149,963, which issued on Apr. 3, 2012; which is a continuation of U.S. patent application Ser. No. 11/754,013, filed May 25, 2007, now U.S. Pat. No. 7,412,013, which issued on Aug. 12, 2008; which is a continuation of U.S. patent application Ser. No. 11/088,116, filed Mar. 23, 2005, now U.S. Pat. No. 7,236,547, which issued on Jun. 26, 2007; which is a continuation of U.S. patent application Ser. No. 10/629,429, filed Jul. 29, 2003, now U.S. Pat. No. 7,187,732, which issued on Mar. 6, 2007; which claims the benefit of U.S. Provisional Application No. 60/399,818 filed on Jul. 31, 2002, which are all incorporated by reference as if fully set forth.
- This application relates to wireless communication and wireless devices. More particularly, the invention relates to initialization of a communication link between a base station (BS) and a user equipment (UE).
- During an initial cell search (ICS) or power-up of a UE, a training sequence of known symbols is used by the receiver to estimate the transmitted signal. In a time division duplex (TDD) signal, for example, the midamble of a TDD frame conventionally contains the training sequence of symbols. The conventional cell search process consists of a
Step 1 algorithm which processes a primary synchronization code (PSC) on the primary synchronization code channel (PSCH) for synchronization channel (SCH) location determination. AStep 2 algorithm processes the secondary synchronization codes (SSC) for code group determination and timeslot synchronization, and aStep 3 algorithm performs midamble processing. - Variable control oscillators (VCOs) are commonly used at the end of an automatic frequency control (AFC) process to adjustably control the frequency of the receiver to achieve synchronization between a transmitter and a receiver. The input for the VCO is a control voltage signal, which is typically generated by a control circuit that processes the amplitude and phase of the received symbols. A common problem during an AFC process is the initial fluctuations resulting from a potentially significant frequency offset between the transmitter and the receiver.
- A method and apparatus for use in connection with wireless communication to adjust the frequency of an oscillator to synchronize with a received signal by correlating a synchronization code channel with training sequences to estimate positive and negative offsets which are employed to estimate an error, which is then filtered. The filtered output preferably provides a voltage controlling a voltage controlled oscillator (VCO). The same technique may be employed to control a numeric controlled oscillator (NCO).
- The invention will be understood from the following description and drawings in which like elements are designated by like numerals and, wherein:
-
FIG. 1 is a block diagram showing the phase rotation approach for start-up AFC. -
FIGS. 2A and 2B , taken together, comprise a block diagram of the interaction between start-up AFC andalgorithm Steps -
FIG. 2 shows the manner in whichFIGS. 2 a and 2 b are arranged to create a complete block diagram. -
FIG. 3 shows a process diagram for a PI filter. -
FIG. 1 is a block diagram of a start-up adaptive frequency control (AFC) 10 used to reduce the frequency offset between a base station (BS) and user equipment (UE) during initial cell search procedure. Start-up AFC uses a phase rotation approach, which is based on the correlations of two sequences with the primary synchronization code (PSC). The storedPSC sequence 12 is rotated in opposing directions at 14, 14 a, 16, 16 a to respectively determine correlations with the receivedsequence 18 at 20 and 22. The absolute values (a and b) are obtained at 24 and 26 and to obtain the value -
- from
circuit 27, where c is an arbitrary constant provided to prevent division by zero. The phase rotation at −3 kHz alternatively can be replaced by a conjugate of a rotated PSC sequence at 3 kHz since the PSC sequence can only have values of (1+j) and (−1−j). - During start-up AFC process, it is assumed that the PSC location provided is correct. Once
Step 1 completes generation of the first outputs, the start-up AFC starts running. TheStep 1 process and start-up AFC process run in parallel. Optimally, start-up AFC reduces the frequency offset from 6 kHz to less than 2 kHz in the least number of iterations. Table 1 shows a particular advantage of frequency correction which is an increase in allowable integrations. The number of integrations is limited, however, due to chip slip. The chip-slip upper boundary is 0.5 Tc since the maximum correlation is generated one sample later for a method utilizing twice the chip rate sampling. Table 1 summarizes the allowable number of integrations as frequency offset is reduced. Table 2 provides information on performance degradation for a coherent combining technique in the presence of carrier frequency offset. -
TABLE 1 Frequency Offset vs. Number of Integrations Allowed Slip per Frequency Offset frame Number of integrations allowed ±6 kHz = ±3 ppm 0.1152 Tc 4 ±4 kHz = ±2 ppm 0.0768 Tc 6 ±2 kHz = ±1 ppm 0.0384 Tc 13 ±1 kHz = ±0.5 ppm 0.0192 Tc 26 -
TABLE 2 Frequency Offset vs. Code Length for Coherent Combining Length of the code integrated Carrier frequency Offset Loss in dB coherently Fc = 2 GHz 2.42 256 ±3 ppm 6 kHz 1.04 256 ±2 ppm 4 kHz 0.26 256 ±1 ppm 2 kHz 0.06 256 ±0.5 ppm 1 kHz 12.62 512 ±3 ppm 6 kHz 4.53 512 ±2 ppm 4 kHz 1.04 512 ±1 ppm 2 kHz 0.26 512 ±0.5 ppm 1 kHz - The start-up AFC procedure includes a mechanism to realign the primary synchronization code (PSC) position that may shift during correction. The
Step 1 procedure can be run to eliminate the need for the mechanism while the start-up AFC algorithm is running. TheStep 1 procedure updates the peak location every 4th frame. -
FIG. 2 depicts the parallel processing relationship among start-up AFC andSteps Step 1 and start-up AFC. SinceStep 1 works in parallel with the startup AFC, there is no need for a code tracker circuit to follow a given path. Eachtime Step 1 updates an output that is based on the largest detected value, start-up AFC uses the new peak location to estimate the new frequency offset. - The frequency estimator block (FEB) 31 of the start-up AFC comprises a Sequence Locator and
Splitter 32, frequency estimators 34-38, a proportional plus integral (PI)filter 42, and a voltage controlled oscillator (VCO) or numeric controlled oscillator (NCO) 46 coupled toPI filter 42 through thesign flop 44. Theinput 32 a to the Sequence Locator andSplitter 32 includes the PSC peak location chip-offset provided byStep 1. Start up AFC 30 is an open loop gain control block that steps through pre-defined gain levels in order to set proper input power level before digitizing the input. The main input to bothStep 1 and the Sequence Locator andSplitter 32 is sampled at twice the chip rate with a length of 76,800 complex elements. Since the chip-offset points to the peak location, the beginning of the PSC is 511 samples before the chip-offset. The outputs of the Sequence Locator andSplitter 32 are generated by the following general equation: -
Output=input[i−511]i Eq. (1) - Accordingly, the three particular outputs of the Sequence Locator and
Splitter 32 are represented by the following equations for early (32 b), punctual (32 c) and late 32(d) estimates: -
Early[i]=input[i−511]i=offset−1,offset,offset+1, . . . ,offset+510 Eq. (2) -
Punctual[i]=input[i−511]i=offset,offset+1,offset+2, . . . ,offset+511 Eq. (3) -
Late[i]=input[i−511]i=offset+1,offset+2,offset+3, . . . ,offset+512 Eq. (4) - Although the Locator and
Splitter 32 in the example given inFIG. 2 , is a PSC locator, it should be understood the same approach can be used with any received sequences other than PSC. - The input samples to the Sequence Locator and Splitter are taken at twice the chip rate.
- The frequency estimators 34, 36 and 38 each receive one of the three inputs provided by Equations (2)-(4). The frequency estimators estimate a different frequency offset, summed at 40, for each input sequence in accordance with
FIG. 1 . The frequency offset, summed at 40, is the summation of early, punctual and late estimates. - The sum of the estimates is passed through a proportional plus integral (PI) filter 42 with coefficients alpha and beta, respectively as shown in detail in
FIG. 3 . The PI filter bandwidth has two settings. Initially, alpha and beta are preferably ½ and 1/256, respectively as shown in detail inFIG. 3 . The loop gain k is set at (k=−1.0). During steady state, alpha and beta are set to 1/16 and 1/1024, respectively.FIG. 3 depicts such aPI filter structure 42. The preferable settings for coefficients alpha and beta are summarized in Table 3. However, other filters may be substituted for the PI filter. -
TABLE 3 PI Filter Coefficients as a Function of Operating Conditions. Condition alpha beta initial ½ 1/256 steady state 1/16 1/1024 - Steady state condition is established when:
- the startup AFC completes at least ten (10) iterations;
- while the last eight (8) outputs (inputs to VCO) are put into a buffer of length eight (8); the difference between the absolute value of the average of the first half and that of the second half is within ±1 kHz; and
- the current output to the VCO is within ±1 kHz of the absolute value of the average of the second half.
- For digital applications, a numerically controlled oscillator (NCO) is used in place of the VCO.
- The start-up AFC algorithm relies on PSC location update to estimate the carrier frequency offset.
Step 1 runs during frequency correction to update the PSC location. As such, it is preferable that start-up AFC is begun immediately following asuccessful Step 1 process, withStep 1 running in parallel.Step 1 continues to provide updated PSC locations once every N1 frames as per theStep 1 algorithm, where N1 is the maximum number of frames for averaging. Start-up AFC is run in this manner for a duration of L frames, with L=24 as the preferred value. TheStep 1FLAG 61 fromcontroller 60 is set when a sequence is detected. TheFEB 31 runs when thecontroller 60 provides an enable condition toFEB 31 at 62. Since the peak locations shift left or right in time, theStep 1 algorithm is run constantly. At the end of L frames, the start-up AFC reduces the frequency offset to about 2 kHz in many cases, which provides considerable enhancement to theStep 2 performance. The inclusion of L frames contributes to the overall cell search delay budget and hence is chosen conservatively to be L=24. -
PSC processing block 66 correlates against the primary synchronization code in (synchronization channel) (SCH) over frames. The SCH location is not known. -
SSC extractor block 68 utilizes the SCH location and extracts only the SCH portion, which is then passed toSSC processing block 70. -
SSC processing block 70 correlates against the secondary synchronization code in synchronization channel over SCH. -
Midamble Extractor block 72 utilizes the SCH location and SSC processing results and extracts the midamble portion to pass tomidamble processing block 74. -
Midamble processing block 74 correlates against possible midambles given by SSC processing and picks the one with the highest energy. - Periodic
Cell Search block 76 performs a process which constantly searches for the best base station for the given period. -
Controller 60 coordinates among stages to synchronize to a base station. -
Layer 1Controller 80 coordinates alllayer 1 related hardware and software in order to maintain proper operation in the receiver.
Claims (20)
1. A method of estimating frequency, the method comprising:
rotating a phase of a stored sequence to produce a first version of a stored sequence having a rotated phase;
correlating a received sequence with the first version of the stored sequence to produce a first phase correlation;
correlating the received sequence with a second version of the stored sequence that has a different rotated phase than the first version to produce a second phase correlation; and
combining the first and second phase correlations to provide the frequency estimate.
2. The method of claim 1 further comprising:
initial cell search processing a received sequence to facilitate the determination of a frequency location of a received signal by:
producing a first frequency estimate based on an early version of the received sequence, a second frequency estimate based on a punctual version of the received sequence, and a third frequency estimate based on a late version of the received sequence;
combining the first, second and third frequency estimates; and
filtering the combined frequency estimates.
3. The method of claim 2 wherein the initial cell search processing is repeated every N frames where N is an integer greater than 0.
4. The method of claim 2 wherein the stored sequence is a primary synchronization code sequence.
5. The method of claim 2 further comprising repeating the rotating, correlating and combining a given number of times to produce a series of frequency estimates for each of the first, second and third frequency estimates.
6. The method of claim 2 wherein a received input power level of the received signal is adjusted prior to the rotating, correlating and combining.
7. The method of claim 6 wherein the received signal is digitized after adjustment of the power level and the power level is set employing open loop gain control.
8. The method of claim 2 wherein the initial cell search processing includes obtaining a primary synchronization code.
9. The method of claim 8 further comprising employing the primary synchronization code to extract a secondary synchronization code from the received signal.
10. The method of claim 2 further comprising using the filtered combined frequency estimates to control the generation of a frequency by a numerically controlled oscillator.
11. The method of claim 2 further comprising using the filtered combined frequency estimates to control the generation of a frequency by a voltage controlled oscillator.
12. A wireless communication device comprising:
a filtering component; and
a frequency estimator configured to rotate a phase of a stored sequence to produce a first version of a stored sequence having a rotated phase, correlate the received sequence with the first version of the stored sequence to produce a first phase correlation, correlate the received sequence with a second version of the stored sequence that has a different rotated phase than the first version to produce a second phase correlation, and combine the first and second phase correlations to provide the frequency estimate.
13. The wireless communication device of claim 12 further comprising an initial cell search processing component configured to process a received sequence to facilitate the determination of a frequency location of a received signal by producing a first frequency estimate based on an early version of the received sequence, a second frequency estimate based on a punctual version of the received sequence, and a third frequency estimate based on a late version of the received sequence; combining the first, second and third frequency estimates; and filtering the combined frequency estimates with the filtering component.
14. The wireless communication device of claim 13 further comprising a sequence locator associated with the initial cell search processing component and configured to selectively produce received signal input for the frequency estimator.
15. The wireless communication device of claim 13 wherein the frequency estimator is configured to use is a primary synchronization code as the received sequence.
16. The wireless communication device of claim 13 wherein the filtering component is configured to selectively integrate frequency estimates responsive to an initial or steady state conditions of a cell search process.
17. The wireless communication device of claim 13 wherein the filtering component is a Proportional integral (PI) filter.
18. The wireless communication device of claim 13 further comprising an oscillator configured to produce an adjusted frequency during initial cell search using the filtered combined frequency estimates.
19. The wireless communication device of claim 18 wherein the oscillator is a voltage controlled oscillator (VCO).
20. The wireless communication device of claim 18 wherein the oscillator is a numeric controlled oscillator (NCO).
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US13/757,368 US20130142292A1 (en) | 2002-07-31 | 2013-02-01 | Method and apparatus for estimating frequency |
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US39981802P | 2002-07-31 | 2002-07-31 | |
US10/629,429 US7187732B2 (en) | 2002-07-31 | 2003-07-29 | Start-up automatic frequency control (AFC) method and apparatus |
US11/088,116 US7236547B2 (en) | 2002-07-31 | 2005-03-23 | Start-up automatic frequency control (AFC) method and apparatus |
US11/754,013 US7412013B2 (en) | 2002-07-31 | 2007-05-25 | Start-up automatic frequency control (AFC) method and apparatus |
US12/185,361 US8149963B2 (en) | 2002-07-31 | 2008-08-04 | Start-up automatic frequency control (AFC) method and apparatus |
US13/438,595 US8385482B2 (en) | 2002-07-31 | 2012-04-03 | Start-up automatic frequency control (AFC) method and apparatus |
US13/757,368 US20130142292A1 (en) | 2002-07-31 | 2013-02-01 | Method and apparatus for estimating frequency |
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US11/088,116 Expired - Fee Related US7236547B2 (en) | 2002-07-31 | 2005-03-23 | Start-up automatic frequency control (AFC) method and apparatus |
US11/754,013 Expired - Fee Related US7412013B2 (en) | 2002-07-31 | 2007-05-25 | Start-up automatic frequency control (AFC) method and apparatus |
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US13/438,595 Expired - Fee Related US8385482B2 (en) | 2002-07-31 | 2012-04-03 | Start-up automatic frequency control (AFC) method and apparatus |
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US11/088,116 Expired - Fee Related US7236547B2 (en) | 2002-07-31 | 2005-03-23 | Start-up automatic frequency control (AFC) method and apparatus |
US11/754,013 Expired - Fee Related US7412013B2 (en) | 2002-07-31 | 2007-05-25 | Start-up automatic frequency control (AFC) method and apparatus |
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-
2003
- 2003-07-25 TW TW092120457A patent/TWI224740B/en not_active IP Right Cessation
- 2003-07-25 TW TW095126609A patent/TWI324023B/en active
- 2003-07-28 AU AU2003254244A patent/AU2003254244A1/en not_active Abandoned
- 2003-07-28 EP EP03772022.4A patent/EP1540912B1/en not_active Expired - Lifetime
- 2003-07-28 WO PCT/US2003/023658 patent/WO2004012463A2/en not_active Application Discontinuation
- 2003-07-29 US US10/629,429 patent/US7187732B2/en not_active Expired - Fee Related
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2004
- 2004-03-08 TW TW093106094A patent/TW200509706A/en unknown
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2005
- 2005-03-23 US US11/088,116 patent/US7236547B2/en not_active Expired - Fee Related
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2007
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2008
- 2008-08-04 US US12/185,361 patent/US8149963B2/en not_active Expired - Fee Related
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2012
- 2012-04-03 US US13/438,595 patent/US8385482B2/en not_active Expired - Fee Related
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2013
- 2013-02-01 US US13/757,368 patent/US20130142292A1/en not_active Abandoned
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EP1540912B1 (en) | 2013-04-10 |
US7236547B2 (en) | 2007-06-26 |
WO2004012463A2 (en) | 2004-02-05 |
AU2003254244A8 (en) | 2004-02-16 |
US20040022333A1 (en) | 2004-02-05 |
US20050163266A1 (en) | 2005-07-28 |
US20120201335A1 (en) | 2012-08-09 |
AU2003254244A1 (en) | 2004-02-16 |
US7412013B2 (en) | 2008-08-12 |
TWI224740B (en) | 2004-12-01 |
US8385482B2 (en) | 2013-02-26 |
TW200401982A (en) | 2004-02-01 |
EP1540912A4 (en) | 2006-03-15 |
US20070230634A1 (en) | 2007-10-04 |
TW200509706A (en) | 2005-03-01 |
US20080285689A1 (en) | 2008-11-20 |
TW200723900A (en) | 2007-06-16 |
TWI324023B (en) | 2010-04-21 |
US7187732B2 (en) | 2007-03-06 |
US8149963B2 (en) | 2012-04-03 |
EP1540912A2 (en) | 2005-06-15 |
WO2004012463A3 (en) | 2005-03-24 |
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