CN105187333A - High-carrier and high-modulation-level OFDM sampling frequency offset blind estimation method - Google Patents
High-carrier and high-modulation-level OFDM sampling frequency offset blind estimation method Download PDFInfo
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Abstract
The invention relates to a high-carrier and high-modulation-level OFDM sampling frequency offset blind estimation method, and especially relates to a sampling frequency offset blind estimation method based on an NG-DSL system. The method comprises the steps as follows: (1) determining to-be-estimated OFDM symbols demodulated by a receiving end; (2) determining the number M of linear fitting sections and the section length L of each to-be-estimated symbol; and (3) estimating the normalized sampling frequency offset of the system by carrying out segmental linear fitting blind estimation on each symbol. The estimation method of the invention has the advantages of high estimation precision, high convergence speed, and no need for band occupation.
Description
Technical field
The present invention relates to communication technical field, more specifically, relate to the sampling frequency synchronization method of the horizontal ofdm system of a kind of high carrier number high modulation.
Background technology
Along with the fast development of the Internet, in order to meet the growing bandwidth demand of people, access technology is more at a high speed brought into schedule.Generation digital subscribers feeder (NG-DSL, NextGenerationDigitalSubscriberLine) technology is following most important high-speed wired access technology, can reach more than 1Gbps access rate, will promote network speed significantly.
NG-DSL system is a kind of OFDM Systems, and its modulation system has the feature of high sub-carrier number and high QAM modulation.These two features make NG-DSL system have very high bandwidth sum transmission rate, but also make NG-DSL system very harsh for the requirement that signal is synchronous simultaneously.Among wired ofdm signal, the mainly sampling frequency synchronization of the net synchronization capability of influential system, in the ofdm system of this high carrier wave of NG-DSL, two-forty, the impact of sampling frequency offset is very serious, and the high-speed transfer of system needs estimate sampling frequency offset accurately and compensate.
Summary of the invention
In order to overcome the deficiency that prior art exists, the present invention proposes the high carrier number high modulation horizontal OFDM sampling frequency offset blind estimating method of a kind of high estimated accuracy, estimating speed.
To achieve these goals, technical scheme of the present invention is as follows:
A kind of high carrier number high modulation horizontal OFDM sampling frequency offset blind estimating method, concrete steps are as follows:
A) get m, m+1, m+2 tri-OFDM symbol after receiving terminal IFFT demodulation to go to estimate normalization sampling frequency offset Δ f, for these three OFDM symbol for estimating, first determine that the sample value of the matching hop count M that each symbol is total and every section is counted L according to partition strategy;
B) for the 1st section of sample value data of m OFDM symbol, due to the actual phase side-play amount that data in section cause because of sampling frequency offset
sample value constellation point can not be made to exceed between correct constellation point decision area, so its actual phase deviation amount can be obtained by planisphere judgement
right
data adopt least-squares algorithm to simulate notional phase deviation straight line after carrying out medium filtering
then according to notional phase deviation straight line
draw the frequency deviation estimated value Δ f of the 1st section of sample value data
1;
C) for the 2nd section of sample value data of m OFDM symbol, first by the notional phase side-play amount of the frequency deviation estimated value Δ f1 section of obtaining of the 1st section end sample value
then by this amount, undertaken of the data phase of the 2nd section is revised, namely
adjudicated the actual phase obtaining the 2nd segment data by constellation after correction
again with initial phase during reception
carry out the actual phase side-play amount making difference acquisition the 2nd segment data
then by the actual phase departure of front 2 segment datas
be combined, then medium filtering adopts least-squares algorithm linear fitting to draw the notional phase deviation straight line of front 2L length sample value data
last according to notional phase deviation straight line
obtain the estimated value Δ f of first 2 sections
2;
D) for m OFDM symbol the 3rd, 4 ..., M section, still adopt the mode of similar c) step.First with the Δ f estimated the last period
m-1go the notional phase side-play amount of the section of obtaining end sample value
then adjudicate by constellation the phase pushing figure obtaining its reality again to after the phase only pupil filter of M segment data
with actual phase side-play amount above
unify, then medium filtering adopts least-squares algorithm linear fitting to draw the notional phase offset linear of M*L length sample value data above
again according to notional phase deviation straight line
obtain the sampling frequency offset estimated value Δ f of front M segment data
m, get Δ f
mas the final sampling frequency offset estimated value Δ f of m OFDM symbol
a;
E) for m+1, m+2 OFDM symbol, ~ d is still adopted b)) step obtains its sampling frequency offset estimated value Δ f
b, Δ f
c, the average of the estimated value of these 3 symbols is as sampling frequency offset estimated value the most at last, namely
Further, in the above-mentioned methods, described step a) in choosing of these three OFDM symbol of m, m+1, m+2 be an empirical value, generally choose interior 3 symbols relatively rearward of front 10 symbols of receiving terminal restituted signal, select the 6th, 7,8 OFDM symbol, i.e. m=6 in the present invention.
After determining 3 symbols of estimation sampling frequency offset, obtained segments M and the segment length L of these 3 each symbols of OFDM symbol by inquiry partition strategy, wherein partition strategy is the empirical value drawn according to real system environmental simulation, and concrete deterministic process is as follows:
1) first by the maximum possible sampling frequency offset Δ f of observation certainty annuity
0, the algorithm for estimating that the present invention proposes requires that the sample offset of system is no more than 20ppm, and system signal noise ratio is at more than 30dB.
2) then carry out mass data emulation, determine that sampling frequency offset is Δ f
0time phase noise Δ θ caused by each symbol ICI (InterCarrierInterference) size, the OFDM symbol of simulation process transmitting terminal all adopts pilot data, and Δ θ is calculated by following formula:
(1) in formula
for the Received signal strength of each subcarrier is relative to actual phase deviation when sending, if OFDM symbol data when sending are { P
m, 1, P
m, 2..., P
m,N, the OFDM symbol data obtained after receiving terminal demodulation are { R
m, 1, R
m, 2..., R
m,N, then
calculated by following formula and obtain:
Wherein angle () is for getting phase angle function, and m is current OFDM symbol number, and N is the carrier number of each OFDM symbol, and k represents a kth subcarrier;
(1) in formula
be the notional phase side-play amount of each sub-carrier signal, tried to achieve by following formula:
Wherein m represents m OFDM symbol, and N is the carrier number of each OFDM symbol, and k represents a kth subcarrier, and Δ f represents current normalization sampling frequency offset, herein by Δ f
0substitute into the notional phase side-play amount of each sub-carrier signal under above formula calculating present case.
3) after obtaining the phase noise Δ θ of each subcarrier, if the maximum permission angle of phase displacement of planisphere is α under current QAM modulation level, α is the definite value determined according to the geometrical relationship of the constellation point in the planisphere of actual QAM modulation level, observe the image of Δ θ/α ratio of each carrier data of receiving terminal demodulation, when sample number above according in the sample value ratio of Δ θ >0.5 α reach 5% time, the sample value of getting now is counted and to be counted L as total matching sample value
m.
4) formula is passed through
LS
mΔf
0＝0.5α(4)
Obtain the segment length L of each symbol, wherein S
mbe the constant determined by OFDM current sign, it is defined as follows:
Wherein m represents m OFDM symbol, and be the carrier number of each OFDM symbol by N, Δ f represents current normalization sampling frequency offset, then according to formula simultaneously:
L
M＝M*L(6)
Obtain the hop count M of each symbol, new blind estimate algorithm only needs front 10 symbols just can complete estimation, generally calculates segment length L and the hop count M of front 10 symbols.
Described step c), d) in S
mthe constant determined by OFDM current sign, the S namely in (5) formula
m, calculated by (5) formula and try to achieve.
Described step b), c), d) in obtain the actual phase departure of receiving terminal restituted signal by planisphere judgement
be specially: the phase place first directly obtaining receiving demodulation signal
then the phase place that planisphere judgement obtains the constellation point after adjudicating is carried out to the restituted signal received or revised signal
the actual phase side-play amount that then signal occurs is
Described step b), c), d) in the filtering siding-to-siding block length n of medium filtering be set to n=4.
Described step b), c), d) according to notional phase departure
go to obtain sampling frequency offset, specific as follows: the notional phase bias offset straight line obtaining front M section sample value data
afterwards, go to calculate present sample frequency deviation value Δ f according to formula (3)
m.
Compared with prior art, the effect that the present invention is useful is:
1, the present invention adopts the mode of blind estimate, is directly estimated sampling frequency offset by the phase information of receiving demodulation signal, improves the availability of frequency spectrum of system; 2, in order to be applicable to the communication system of this kind of high QAM modulation level of NG-DSL, the present invention is estimated sampling frequency offset by the mode of stages cycle iteration, extends the sample value that each OFDM symbol can be used for estimating and counts, and then improve estimated accuracy; 3, the present invention only need the 6th, 7,8 symbols just can realize high accuracy and estimate, estimating speed is very fast; The present invention, in order to improve stability and the precision of estimation, added median filtering process before the every segment signal data met each OFDM carry out linear fit estimation.
Accompanying drawing explanation
Fig. 1 is 16QAM maximum permission phase rotation angle schematic diagram.
Fig. 2 is that in 10ppm situation, the phase jitter of ICI affects size.
Fig. 3 is sectional linear fitting blind estimating method schematic diagram.
Fig. 4 is estimation curve of the present invention and evaluated error curve synoptic diagram.
Fig. 5 is the estimation curve schematic diagram of each algorithm under 0.5ppm.
Fig. 6 is the estimation curve schematic diagram of each algorithm under 3ppm.
Fig. 7 is the estimation curve schematic diagram of each algorithm under 10ppm.
Fig. 8 is realization flow figure of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention will be further described, to be interpretated more in-depth the technical characteristic of the inventive method and advantage.But embodiments of the present invention are not limited to this.
The invention provides the sampling frequency offset blind estimating method of a kind of high estimated accuracy, estimating speed, concrete implementation step is as follows:
1. determine OFDM symbol to be estimated
First get 3 OFDM symbol such as m, m+1, m+2 after receiving terminal IFFT demodulation to go to estimate normalization sampling frequency offset Δ f as sample, wherein choosing of these 3 OFDM symbol of m, m+1, m+2 is an empirical value.Algorithm for estimating in this paper requires that the sampling frequency offset of system is no more than 20ppm, and system signal noise ratio is at more than 30dB, generally chooses 3 symbols relatively rearward in front 10 symbols of receiving terminal in this case, as symbol 6,7,8.
2. determine linear fit segments M and the segment length L of each symbol
After determining 3 OFDM symbol to be estimated, obtained segments M and the segment length L of these 3 each symbols of OFDM symbol by inquiry partition strategy, wherein partition strategy is the empirical value drawn according to real system environmental simulation, and concrete deterministic process is as follows:
I) first by the maximum possible sampling frequency offset Δ f of large discharge observation certainty annuity
0.
II) then carry out mass data emulation, determine that sampling frequency offset is Δ f
0time phase noise Δ θ caused by each symbol ICI (InterCarrierInterference) size, the OFDM symbol of simulation process transmitting terminal all adopts pilot data, and Δ θ is calculated by following formula:
(1) in formula
for the Received signal strength of each subcarrier is relative to actual phase deviation when sending, if OFDM symbol data when sending are { P
m, 1, P
m, 2..., P
m,N, the OFDM symbol data obtained after receiving terminal demodulation are { R
m, 1, R
m, 2..., R
m,N, then
calculated by following formula and obtain:
Wherein angle () is for getting phase angle function, and m is current OFDM symbol number, and N is the carrier number of each OFDM symbol, and k represents a kth subcarrier;
(1) in formula
be the notional phase side-play amount of each sub-carrier signal, tried to achieve by following formula:
Wherein m represents m OFDM symbol, and N is the carrier number of each OFDM symbol, and k represents a kth subcarrier, and Δ f represents current normalization sampling frequency offset, herein by Δ f
0substitute into the notional phase side-play amount of each sub-carrier signal under above formula calculating present case.
III) after obtaining the phase noise Δ θ of each subcarrier, determine that the maximum permission angle of phase displacement of planisphere is α under current QAM modulation level, α is the definite value determined according to the geometrical relationship of the constellation point in the planisphere of actual QAM modulation level, as the maximum permission phase deviation angle schematic diagram that Fig. 1 is system under 16QAM modulation level, according to geometric knowledge, can know that upper figure point A moves on to B position angle of phase displacement size is α=0.5307 (radian), when the some deviation angle of planisphere exceedes this angle time, receiving terminal just likely error code, when deviation angle is within a, can ensure a little not error code, can maximum permission angle of phase displacement be in like manner α=0.0318 (radian) in 1024QAM situation.Observe the image of Δ θ/α ratio of each carrier data of receiving demodulation, when the ratio of the Δ θ >0.5 α of sample number certificate above reaches 5%, get current sample value and count and to count L as total matching sample value
mas shown in Figure 2, Δ θ/α ratio situation of (a), (b), (c) three figure these three OFDM symbol of receiving terminal the 1st, 4,8 when being respectively that NG-DSL system signal noise ratio is 55dB, normalization sampling frequency offset is 10ppm, modulation level is 1024QAM, according to the situation of these three figure, when sampling frequency offset is 10ppm, only have data fit aforementioned condition within general 1200 subcarriers above can as the sample value data of matching, therefore as system maximum possible sampling frequency offset Δ f
0during for 10ppm, total matching length can be taken as L
m=1200.
V) formula is passed through
LS
mΔf
0＝0.5α(4)
Obtain the segment length L of each symbol, wherein S
mbe the constant determined by OFDM current sign, it is defined as follows:
Wherein m represents m OFDM symbol, and be the carrier number of each OFDM symbol by N, Δ f represents current normalization sampling frequency offset, then according to formula simultaneously
L
M＝M*L(6)
Obtain the hop count M of each symbol, new blind estimate algorithm only needs front 10 symbols just can complete estimation, generally calculates segment length L and the hop count M of front 10 symbols.By emulation can obtain NG-DSL system sampling frequency offset be 10ppm, under signal to noise ratio is 55dB, modulation level is 1024QAM situation, symbol 1 to the segment length L of symbol 10 is: [50616910172564639343027], and symbol 1 is [271217222732364044] to the hop count of the matching the carried out estimation of symbol 10.
3. pair each symbol carries out sectional linear fitting blind estimate
After the matching segment length L determining each OFDM symbol and segments M, to the value of each OFDM symbol to be estimated by sectional linear fitting blind estimate algorithm determination sampling frequency offset Δ f, as shown in Figure 3, its concrete steps are as follows for algorithm schematic diagram:
1) for the 1st section of sample value data of m OFDM symbol, due to the actual phase side-play amount caused because of sampling frequency offset of data in section
allow in offset angle in the maximum phase of planisphere, so sample value constellation point can not be caused to exceed between correct constellation point decision area, therefore can obtain its actual phase deviation amount by planisphere judgement
as blue line part in Fig. 3, right
data adopt least-squares algorithm to simulate notional phase deviation straight line after carrying out medium filtering
as straight line portion red in Fig. 3, then according to notional phase deviation straight line
draw the estimated value Δ f of the 1st section
1;
2) for the 2nd section of sample value data of m OFDM symbol, first by the notional phase side-play amount of the frequency deviation estimated value Δ f1 section of obtaining of the 1st section end sample value
then by this amount, the phase place of the data of the 2nd section is revised, namely
adjudicated the actual phase obtaining second segment data by constellation after correction
the actual phase side-play amount making difference acquisition the 2nd segment data is carried out again with phase place when receiving
then by the actual phase departure of front 2 segment datas
be combined, then medium filtering adopts least-squares algorithm linear fitting to draw the notional phase deviation straight line of front 2L length sample value data
last according to notional phase deviation straight line
obtain the estimated value Δ f of first 2 sections
2;
3) for m OFDM symbol the 3rd, 4 ..., M section, still adopt the mode of similar c) step.First with the Δ f estimated the last period
m-1go the notional phase side-play amount of the section of obtaining end sample value
then adjudicate by constellation the phase pushing figure obtaining its reality again to after the phase only pupil filter of M segment data
with actual phase side-play amount above
unify, then medium filtering adopts least-squares algorithm linear fitting to draw the notional phase offset linear of M*L length sample value data above
again according to notional phase deviation straight line
obtain the sampling frequency offset estimated value Δ f of front M segment data
m, get Δ f
mas the final sampling frequency offset estimated value Δ f of m OFDM symbol
a;
4) for m+1, m+2 OFDM symbol, ~ d is still adopted b)) step obtains its sampling frequency offset estimated value Δ f
b, Δ f
c, the average of the estimated value of these 3 symbols is as sampling frequency offset estimated value the most at last, namely
Above-mentioned steps 2), 3) in S
mbeing the constant determined by OFDM current sign, is the S in (5) formula
m, calculated by (5) formula and try to achieve.
Above-mentioned step 2), 3), 4) in obtain the actual phase departure of receiving terminal restituted signal by planisphere judgement
be specially: the phase place first directly obtaining receiving demodulation signal
then the phase place that planisphere judgement obtains the constellation point after adjudicating is carried out to the restituted signal received or revised signal
the actual phase side-play amount that then signal occurs is
Above-mentioned step 1), 2), 3) in the filtering siding-to-siding block length n of medium filtering be set to n=4.
Above-mentioned steps 1), 2), 3) according to notional phase departure
go to obtain sampling frequency offset, specific as follows: the notional phase bias offset straight line obtaining front M section sample value data
afterwards, go to calculate present sample frequency deviation value Δ f according to formula (3)
m.
Fig. 4 emulates when sampling frequency offset is 0.5ppm, subcarrier numerical digit 2048, the estimation procedure of sectional linear fitting blind estimate algorithm when modulation level is 1024QAM, SNR=55dB; Wherein scheme the estimation procedure that (a), (c), (e) are respectively the 6th, 7,8 these three symbols of receiving terminal restituted signal, and (b), (d), (f) are the relative errors that their are estimated, each OFDM symbol is along with the increase estimating hop count M in symbol as seen from the figure, and algorithm can the total length L of matching
malso constantly increase, estimated value also more and more near actual value, thus makes the error amount of estimation also constantly diminish.
The present invention has carried out performance evaluation and emulation to said method, specific as follows:
Be in the NG-DSL system of 50m at a line length, each OFDM data bit length is 2048 (FFT/IFFT length), and system modulation level is 1024QAM, and normalization sampling frequency offset Δ f is 0.5ppm, the emulation of the new sample frequency estimated performance under 3ppm, 10ppm tri-kinds of different situations.
The sampling frequency offset value of setting NG-DSL maximum possible is Δ f
0=10ppm, now obtaining symbol 1 to the segment length L of symbol 10 is: [50616910172564639343027], symbol 1 is [271217222732364044] to the hop count of the matching the carried out estimation of symbol 10.
The present invention and two kinds of traditional methods are compared, method 1 is the sampling frequency synchronization method proposed in document " EstimationandcompensationoffrequencyoffsetinDAC/ADCclock sinOFDMsystems ", and method 2 is sampling frequency synchronization methods that document " effect of Sampling Frequency Offset on MB-OFDM-UWB System and algorithm for estimating " proposes.Fig. 5,6,7 is estimation curve of these three kinds of algorithms in three kinds of sampling frequency offset situations, and experiment number is 300 times, for convenience of description, gets average to Simulation results, obtains result as following table:
Table 1 three kinds of method estimated accuracy contrast tables
Can know in conjunction with chart, new algorithm all shows reasonable performance when 3 kinds of frequency deviations, when sampling frequency offset is within 10ppm, the relative estimation relative deviation of new algorithm is within 0.5%, and algorithm 1,2 is all almost 1%, therefore estimated accuracy of the present invention is all better than other two kinds of algorithms generally.
Above-described embodiments of the present invention, do not form limiting the scope of the present invention.Any amendment done within spiritual principles of the present invention, equivalent replacement and improvement etc., all should be included within claims of the present invention.
Claims (10)
1. a high carrier number high modulation horizontal OFDM sampling frequency offset blind estimating method, is characterized in that, comprise the steps:
A) getting these three OFDM symbol of m, m+1, m+2 after receiving terminal IFFT demodulation to go to estimate sampling frequency offset Δ f, for these three OFDM symbol for estimating, first determining that the sample value of the matching hop count M that each symbol is total and every section is counted L according to partition strategy;
B) for the 1st section of sample value data of m OFDM symbol, due to data in section because the actual phase rotation amount that sampling frequency offset causes can not cause sample value constellation point to exceed between correct constellation point decision area, so border phase deviation amount in fact can be obtained by planisphere judgement
right
data adopt least-squares algorithm to simulate notional phase deviation straight line after carrying out medium filtering
then according to notional phase deviation straight line
draw the frequency deviation estimated value Δ f of the 1st section
1;
C) for the 2nd section of sample value data of m OFDM symbol, first by the notional phase side-play amount of the frequency deviation estimated value Δ f1 section of obtaining of the 1st section end sample value
s
mit is the constant determined by OFDM current sign; Then by this amount, undertaken of the data phase of the 2nd section is revised, namely
adjudicated the actual phase obtaining the 2nd segment data by constellation after correction
again with initial phase during reception
carry out the actual phase side-play amount making difference acquisition the 2nd segment data
then by the actual phase departure of front 2 segment datas
be combined, then medium filtering adopts least-squares algorithm linear fitting to draw the notional phase deviation straight line of front 2L length sample value data
last according to notional phase deviation straight line
obtain the estimated value Δ f of first 2 sections
2;
D) for m OFDM symbol the 3rd, 4 ..., M section, still adopt the mode of above-mentioned c) step, first with the Δ f estimated the last period
m-1go the notional phase side-play amount of the section of obtaining end sample value
then adjudicate by constellation the phase pushing figure obtaining its reality again to after the phase only pupil filter of M segment data
with actual phase side-play amount above
unify, then medium filtering adopts least-squares algorithm linear fitting to draw the notional phase offset linear of M*L length sample value data above
again according to notional phase deviation straight line
obtain the sampling frequency offset estimated value Δ f of front M segment data
m, get Δ f
mas the final sampling frequency offset estimated value Δ f of m OFDM symbol
a;
E) for m+1, m+2 OFDM symbol, ~ d is adopted b) equally) step obtains its sampling frequency offset estimated value Δ f
b, Δ f
c, the average of the estimated value of these three symbols is as sampling frequency offset estimated value the most at last, namely
2. high carrier number high modulation according to claim 1 horizontal OFDM sampling frequency offset blind estimating method, it is characterized in that, described step a) in choosing of these three OFDM symbol of m, m+1, m+2 be an empirical value, 3 symbols rearward in front 10 symbols choosing receiving terminal restituted signal.
3. high carrier number high modulation according to claim 1 horizontal OFDM sampling frequency offset blind estimating method, is characterized in that, described step c), d) in S
mbe the constant determined by OFDM current sign, it is defined as follows:
wherein m represents m OFDM symbol, and N is the carrier number of each OFDM, and L is the length of Cyclic Prefix.
4. high carrier number high modulation according to claim 1 horizontal OFDM sampling frequency offset blind estimating method, it is characterized in that, described step a) in partition strategy be the empirical value obtained according to system emulation, determine that the specific practice of the segment length L of each OFDM symbol and total matching hop count M is as follows:
1) the maximum sampling frequency offset Δ f of first certainty annuity
0;
2) then emulated by mass data, determine that maximum sampling frequency offset is Δ f
0time each symbol size of the phase noise Δ θ caused by ICI of introducing due to sampling frequency offset, then the ratio images of Δ θ/α is observed, α is the maximum permission phase deviation angle of the planisphere under current modulation level, when sample number above according in the sample value ratio of Δ θ >0.5 α reach 5% time, the sample value of getting now is counted and to be counted L as total matching sample value
m;
3) LS is made
mΔ f
0=0.5 α obtains the segment length L of each symbol, simultaneously by L
m=M*L obtains the hop count M of each symbol.
5. high carrier number high modulation according to claim 4 horizontal OFDM sampling frequency offset blind estimating method, is characterized in that, described maximum sampling frequency offset Δ f
0an empirical value, by obtaining the large discharge observation of system, described maximum sampling frequency offset Δ f
0within 20ppm, system signal noise ratio is more than 30dB.
6. high carrier number high modulation according to claim 1 horizontal OFDM sampling frequency offset blind estimating method, is characterized in that, described step b), c), d) according to notional phase departure
go to obtain sampling frequency offset, specific as follows: the notional phase bias offset straight line obtaining front M section sample value data
afterwards, according to formula
calculate present sample frequency deviation value Δ f
m, wherein k is subcarrier sequence number, and m represents m OFDM symbol, and N is OFDM carrier number, and L is circulating prefix-length, and Δ f is present sample frequency deviation value.
7. high carrier number high modulation according to claim 4 horizontal OFDM sampling frequency offset blind estimating method, is characterized in that, the Δ θ that affects of the phase noise of described ICI is defined as follows:
wherein
for the transmission signal of each subcarrier is relative to actual phase deviation when sending, directly obtained by pilot signal during emulation;
it is the notional phase side-play amount of each sub-carrier signal.
8. high carrier number high modulation according to claim 4 horizontal OFDM sampling frequency offset blind estimating method, it is characterized in that, the maximum permission phase deviation angle α of described planisphere determines according to the geometrical relationship of the constellation point in the planisphere of actual QAM modulation level.
9. high carrier number high modulation according to claim 1 horizontal OFDM sampling frequency offset blind estimating method, is characterized in that, described step b), c), d) in by planisphere judgement obtain its actual phase deviation amount
be specially: the phase place first directly obtaining receiving demodulation signal
then the phase place that planisphere judgement obtains the constellation point after adjudicating is carried out to the restituted signal received or revised signal
the actual phase side-play amount that then signal occurs is
10. high carrier number high modulation according to claim 1 horizontal OFDM sampling frequency offset blind estimating method, is characterized in that, described step b), c), d) in the filtering siding-to-siding block length n of medium filtering be set to n=4.
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| CN108551371A (en) * | 2018-02-14 | 2018-09-18 | 北京邮电大学 | A kind of blind carrier phase estimation method of QAM signals and system |
| CN109120568A (en) * | 2018-08-31 | 2019-01-01 | 北京邮电大学 | Based on frequency shift (FS) determination, removing method, device and the electronic equipment of cluster |
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| CN108551371A (en) * | 2018-02-14 | 2018-09-18 | 北京邮电大学 | A kind of blind carrier phase estimation method of QAM signals and system |
| CN108551371B (en) * | 2018-02-14 | 2020-06-23 | 北京邮电大学 | Method and system for estimating phase of blind carrier of QAM (Quadrature amplitude modulation) signal |
| CN109120568A (en) * | 2018-08-31 | 2019-01-01 | 北京邮电大学 | Based on frequency shift (FS) determination, removing method, device and the electronic equipment of cluster |
| CN109120568B (en) * | 2018-08-31 | 2020-04-03 | 北京邮电大学 | Clustering-based frequency offset determining and eliminating method and device and electronic equipment |
| US11218354B2 (en) | 2018-08-31 | 2022-01-04 | Beijing University Of Posts And Telecommunications | Clustering-based frequency deviation determination and elimination method and device, and electronic apparatus |
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