CN105024799A - Band-limited system timing recovery method based on p-moment - Google Patents
Band-limited system timing recovery method based on p-moment Download PDFInfo
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- CN105024799A CN105024799A CN201510346150.2A CN201510346150A CN105024799A CN 105024799 A CN105024799 A CN 105024799A CN 201510346150 A CN201510346150 A CN 201510346150A CN 105024799 A CN105024799 A CN 105024799A
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Abstract
The invention relates to a band-limited system timing recovery method based on p-moment. In a feedback phase-locked loop, the pth power of a signal module value is adopted for calculating a timing-error detection output value, and p>0 and p is a variable parameter. The method of the invention can be applied to a timing recovery loop, better residual timing error jitter performance can be acquired, and in an AWGN channel, normalized mean square error performance through timing recovery is close to a theoretical Cramer-Rao bound. The method of the invention can be applied to a band-limited communication system with a small roll-off factor, and can be applied to a satellite communication system which needs to improve the spectrum utilization ratio.
Description
Technical field
The present invention relates to digital wireless communication transmission technique field, particularly a kind of limit of the band based on p rank square timing restoration methods.
Background technology
In satellite communication system, usually needing to carry out to sending signal the frequency spectrum that root raised cosine shaping improves signal, reducing the interference to adjacent frequency band.In digital receiver, need that Timed Recovery is carried out to sampled signal and obtain modulation symbol accurately.Timing recovery algorithm is mainly divided into data householder method and non-data-aided method two class.Be difficult to obtain pilot data before Timing Synchronization, therefore more conventional unbound nucleus timing method.Non-data-aided method can be divided into again forward direction timing and feedback timing two class methods.Forward direction timing method is suitable for the communication system of burst transfer, and feeds back the communication system that timing method is suitable for transmission continuously.
In document " F.M.Gardner; A BPSK/QPSK timing-error detector forsampled receivers; IEEE Trans.Commun.; vol.COM-34; pp.423 – 429, May 1986. ", the feedback phase-locked loop timing recovery method based on Gardner Timing Error Detection algorithm (GA) is a kind of blind synchronization method of unbound nucleus, its detector timing properties b, not by the impact of carrier deviation, is used widely in the communication system of transmission continuously.If Received signal strength is expressed as r
k=I
k+ jQ
k, the Timing Error Detection of this algorithm exports e
k, GAbe expressed as:
Wherein, r
k, r
k-1/2represent receiver respectively at 2 times of " two edge points " and " intermediate point " to data symbol rate, Re{} represents the real part asking complex values.Based on this algorithm, scholar Gappmair and Lim etc. are respectively at document " W.Gappmair, S.Cioni, G.E.Corazza, and O.Koudelka, Extended Gardner Detector for Improved Symbol-Timing Recovery of M-PSKSignals, IEEE Trans.Commun., vol.54, pp.1923 – 1927, and " D.Lim Nov.2006. ", A modified Gardner detector for symbol timing recovery of M-PSK signals, IEEE Trans.Commun., vol.52, no.10, pp.1643 – 1647, etc. Oct.2004. " have studied the improvement project of Timing Error Detection algorithm in document.But this class is only applicable to adopt in the communication system of larger shaping roll-off factor based on the timing method of GA algorithm.
Along with high definition, the direct broadcasting satellite of ultra high-definition Digital Television, and the fast development of multimedia the Internet high-speed transfer based on satellite communication, the bandwidth resources of communication satellite coverage are more and more nervous.In the second generation Satellite Digital Video Broadcasting System (DVB-S2X) of expansion, the employing shaping factor improves band system band efficiency close to the root raised cosine forming filter of 0.Now, traditional timing recovery method poor-performing based on GA algorithm,
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of band based on p rank square is provided to limit timing restoration methods, the method is in feedback phase-locked loop, the p power of signal modulus value is adopted to calculate Timing Error Detection output valve, wherein p>0, can obtain better residual timing error jitter performance.
Above-mentioned purpose of the present invention is achieved by following technical solution:
Based on a band limit timing restoration methods for p rank square, mainly comprise the steps:
Step (one), by the sampled signal r from external reception
nuse interpolation filter to carry out filtering interpolation, obtain 2 times to the signal data of character rate, be designated as y
k, wherein, interpolation filter is by interpolation nodes m
kwith relative timing deviation u
kinterpolation fitting is carried out in control, m
k, u
kinitial value be that 0, k gets positive integer;
Step (two), signal data step () obtained use matched filter to carry out matched filtering, obtain filtered data, are designated as x
k-1, x
k-1/2, x
k, wherein x
k, x
k-1represent both sides point sampling data, x
k-1/2represent intermediate point sampled data, wherein, k gets positive integer; Simultaneously by x
k-1, x
kexport, as the output data result of Timed Recovery;
Data x after step (three), calculation of filtered
k, x
k-1/2, x
k-1the p power non-linear value of modulus value is
X
k＝|x
k|
p，X
k-1/2＝|x
k-1/2|
p，X
k-1＝|x
k-1|
p
Wherein: p is positive number;
Step (four), according to filtered data x
k, x
k-1/2, x
k-1the p power non-linear value of modulus value calculates the output variable e of Timing Error Detector
k
e
k＝X
k-1/2(X
k-X
k-1)
；
＝|x
k-1/2|
p(|x
k|
p-|x
k-1|
p)
When step (five), employing first-order filtering loop realize, loop filter is used to carry out loop filtering, control word W to Timing Error Detection output variable ek
k+1update method
W
k+1＝W
k+γe
k
Wherein, W
0=1/N
s, N
sfor the ratio in the data cycle before interpolation filter and after interpolation filter, control word W
k+1go forward one by one step by step; ; The computing formula of γ is
for the detection gain of Timing Error Detector,
for differentiating, τ is the unknown timing error deviate that channel is introduced, B
lfor the bandwidth of loop filter, T
sfor the cycle of data symbol;
Step (six), the control word W that will upgrade
k+1interpolation controller is used to extract interpolation nodes m
k+1with relative timing deviation u
k+1;
Step (seven), return step (), make k=k+1, repeat step () to step (six), complete Timed Recovery to received signal.
In the above-mentioned a kind of limit of the band based on p rank square timing restoration methods, when realizing as adopted second-order filter loop, described control word W
k+1update method is
W
k+1＝W
k+K
1e
k+L
k+1
L
k+1＝L
k+K
2e
k
Wherein, W
0=1/N
s, N
sfor the ratio in the data cycle before interpolation filter and after interpolation filter, upgrade coefficient
Upgrade coefficient
The present invention compared with prior art has following beneficial effect:
(1) the present invention is based on the band limit timing restoration methods of p rank square, be applicable to the situation that roll-off factor is little, be more suitable for the satellite communication band limit system needing to improve the availability of frequency spectrum relative to traditional timing recovery method.
(2) the present invention is based on the band limit timing restoration methods of p rank square, based on the amplitude process of signal, the performance of its Timing Synchronization is not by the impact of carrier deviation, and the performance of its Timing Synchronization and modulation system have nothing to do;
(3) the present invention is based on the band limit timing restoration methods of p rank square, adopt the p power of signal modulus value to carry out Timing Error Detection, detect gain and increase along with p and increase;
(4) the present invention is based on the band limit timing restoration methods of p rank square, under awgn channel, the normalized mean squared error performance of Timed Recovery is limit close to theoretical carat Metro, and the timing jitter variance under low signal-to-noise ratio after Timed Recovery reduces along with p and reduces.
Accompanying drawing explanation
Fig. 1 is the phase-locked loop composition frame chart of the band limit timing restoration methods that the present invention is based on p rank square;
Fig. 2 be the present invention is based on p rank square band limit timing restoration methods at different p, during different α and the S curve of GA algorithm;
The S curve that Fig. 3 is the band limit timing restoration methods that the present invention is based on p rank square when different p, α=0.05;
The S curve slope that Fig. 4 is this band based on p rank square limit system bright timing recovery method when different p, α=0.05;
Fig. 5 is timing jitter convergence curve in the timing acquisition process of the band limit timing restoration methods that the present invention is based on p rank square;
Fig. 6 is timing jitter mean square error (MSE) performance of the band limit timing restoration methods that the present invention is based on p rank square;
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:
Based on a band limit timing restoration methods for p rank square, it is characterized in that comprising the steps:
Step (one), by the sampled signal r from external reception
nuse interpolation filter to carry out filtering interpolation, obtain 2 times to the signal data of character rate, be designated as y
k, wherein, interpolation filter is by interpolation nodes m
kwith relative timing deviation u
kinterpolation fitting is carried out in control, m
k, u
kinitial value be that 0, k gets positive integer;
Step (two), signal data step () obtained use matched filter to carry out matched filtering, obtain filtered data, are designated as x
k-1, x
k-1/2, x
k, wherein x
k, x
k-1represent both sides point sampling data, x
k-1/2represent intermediate point sampled data, wherein, k gets positive integer; Simultaneously by x
k-1, x
kexport, as the output data result of Timed Recovery;
Data x after step (three), calculation of filtered
k, x
k-1/2, x
k-1the p power non-linear value of modulus value is
X
k＝|x
k|
p，X
k-1/2＝|x
k-1/2|
p，X
k-1＝|x
k-1|
p
Wherein: p is positive number;
Step (four), according to filtered data x
k, x
k-1/2, x
k-1the p power non-linear value of modulus value calculates the output variable e of Timing Error Detector
k
e
k＝X
k-1/2(X
k-X
k-1)
；
＝|x
k-1/2|
p(|x
k|
p-|x
k-1|
p)
When step (five), employing first-order filtering loop realize, loop filter is used to carry out loop filtering, control word W to Timing Error Detection output variable ek
k+1update method
W
k+1＝W
k+γe
k
Wherein, W
kinitial value W
0=1/N
s, N
sfor the ratio in the data cycle before interpolation filter and after interpolation filter, control word W
k+1go forward one by one step by step; ; The computing formula of γ is
for the detection gain of Timing Error Detector,
for differentiating, τ is the unknown timing error deviate that channel is introduced, B
lfor the bandwidth of loop filter, T
sfor the cycle of data symbol;
Step (six), the control word W that will upgrade
k+1interpolation controller is used to extract interpolation nodes m
k+1with relative timing deviation u
k+1;
Step (seven), return step (), make k=k+1, repeat step () to step (six), complete Timed Recovery to received signal.
In above-mentioned steps (five), when realizing as adopted second-order filter loop, described control word W
k+1update method is
W
k+1＝W
k+K
1e
k+L
k+1
L
k+1＝L
k+K
2e
k
Wherein, L is made
kinitial value L
0=0, W
kinitial value W
0=1/N
s, N
sfor the ratio in the data cycle before interpolation filter and after interpolation filter, L
k+1and W
k+1go forward one by one step by step, upgrade coefficient
upgrade coefficient
Embodiment 1
The result of the timing recovery method of prior art and timing recovery method of the present invention is compared.
(1) open loop S curve and slope ratio are comparatively
Data acquisition QPSK modulation system, under awgn channel environment, carry out emulation to existing GA algorithm with the band limit timing restoration methods examine repair that the present invention is based on p rank square under SNR=10dB condition and compare, simulation result as shown in Figure 2, Figure 3, Figure 4, as can be seen from Fig. 2: GA algorithm reduces along with roll-off factor α, S curve tends towards stability, and peak value diminishes, and timing recovery method of the present invention works as p=1, when 2, along with roll-off factor α reduces, S curve is tending towards sharp-pointed, and peak value becomes large.As can be seen from Fig. 3: keep α=0.05 constant, timing recovery method of the present invention at p=1,1.5,2,2.5,3,3.5, be tending towards sharp-pointed along with p increases S curve when 4, peak value becomes large.Timing recovery method of the present invention at p=1,1.5,2,2.5,3,3.5, when 4, the slope of S curve as shown in Figure 4, as seen from the figure slope along with p increase and increase.
(2) under tracking mode, timing jitter emulation is compared
Data acquisition QPSK modulates, and frequency-locked loop adopts first-order filtering loop, when not plus noise, keeps loop normalization bandwidth B
lt
s=5 × 10
-3constant, as can be seen from Fig. 5 simulation result, when roll-off factor α=0.05, adopt the convergence rate of timing recovery method of the present invention and the convergence rate of GA algorithm when larger roll-off factor α=0.25 close, as seen from the figure, the shake after timing recovery method convergence of the present invention is less.
Data acquisition QPSK, under awgn channel condition, frequency-locked loop adopts first-order filtering loop, keeps roll-off factor α=0.05, loop normalization bandwidth B
lt
s=5 × 10
-3constant, signal to noise ratio is set to SNR=5dB ~ 30dB respectively, and as can be seen from Fig. 6 simulation result, new algorithm is close to theoretical correction carat Metro limit (MCRB), and GA algorithm detector timing properties b is very poor.At change p=1,2, when 3, along with p increases, detector timing properties b during low signal-to-noise ratio is deteriorated.Meanwhile, when maintenance p=2 is constant, when modulation system is 8PSK signal, detector timing properties b and the QPSK signal timing performance of the inventive method are close, illustrate that this algorithm performance has nothing to do with modulation system.
The above; be only the embodiment of the best of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.
The content be not described in detail in specification of the present invention belongs to the known technology of professional and technical personnel in the field.
Claims (2)
1., based on a band limit timing restoration methods for p rank square, it is characterized in that comprising the steps:
Step (one), by the sampled signal r from external reception
nuse interpolation filter to carry out filtering interpolation, obtain 2 times to the signal data of character rate, be designated as y
k, wherein, interpolation filter is by interpolation nodes m
kwith relative timing deviation u
kinterpolation fitting is carried out in control, m
k, u
kinitial value be that 0, k gets positive integer;
Step (two), signal data step () obtained use matched filter to carry out matched filtering, obtain filtered data, are designated as x
k-1, x
k-1/2, x
k, wherein x
k, x
k-1represent both sides point sampling data, x
k-1/2represent intermediate point sampled data, wherein, k gets positive integer; Simultaneously by x
k-1, x
kexport, as the output data result of Timed Recovery;
Data x after step (three), calculation of filtered
k, x
k-1/2, x
k-1the p power non-linear value of modulus value is
X
k＝|x
k|
p，X
k-1/2＝|x
k-1/2|
p，X
k-1＝|x
k-1|
p
Wherein: p is positive number;
Step (four), according to filtered data x
k, x
k-1/2, x
k-1the p power non-linear value of modulus value calculates the output variable e of Timing Error Detector
k
When step (five), employing first-order filtering loop realize, to Timing Error Detection output variable e
kloop filter is used to carry out loop filtering, control word W
k+1update method
W
k+1＝W
k+γe
k
Wherein, W
0=1/N
s, N
sfor the ratio in the data cycle before interpolation filter and after interpolation filter, control word W
k+1go forward one by one step by step; ; The computing formula of γ is
for the detection gain of Timing Error Detector,
for differentiating, τ is the unknown timing error deviate that channel is introduced, B
lfor the bandwidth of loop filter, T
sfor the cycle of data symbol;
Step (six), the control word W that will upgrade
k+1interpolation controller is used to extract interpolation nodes m
k+1with relative timing deviation u
k+1;
Step (seven), return step (), make k=k+1, repeat step () to step (six), complete Timed Recovery to received signal.
2. a kind of limit of the band based on p rank square timing restoration methods according to claim 1, is characterized in that: when adopting second-order filter loop to realize, described control word W
k+1update method is
W
k+1＝W
k+K
1e
k+L
k+1
L
k+1＝L
k+K
2e
k
Wherein, L
0=0, W
0=1/N
s, N
sfor the ratio in the data cycle before interpolation filter and after interpolation filter, upgrade coefficient
upgrade coefficient
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Cited By (4)
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| CN110752870A (en) * | 2019-10-29 | 2020-02-04 | 中国电子科技集团公司第五十四研究所 | Timing recovery method and device for roll-off coefficient variable broadband satellite transmission system |
| CN111681666A (en) * | 2020-05-21 | 2020-09-18 | 浙江大华技术股份有限公司 | Backup of filter coefficient, device and computer storage medium |
| CN111783280A (en) * | 2020-06-10 | 2020-10-16 | 北京遥测技术研究所 | Single-pulse self-tracking design method based on logarithmic nonlinear detection |
| CN111783280B (en) * | 2020-06-10 | 2024-05-14 | 北京遥测技术研究所 | Single pulse self-tracking design method based on logarithmic non-linear detection |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110752870A (en) * | 2019-10-29 | 2020-02-04 | 中国电子科技集团公司第五十四研究所 | Timing recovery method and device for roll-off coefficient variable broadband satellite transmission system |
| CN111681666A (en) * | 2020-05-21 | 2020-09-18 | 浙江大华技术股份有限公司 | Backup of filter coefficient, device and computer storage medium |
| CN111681666B (en) * | 2020-05-21 | 2022-10-04 | 浙江大华技术股份有限公司 | Backup method and device for filter coefficient and computer storage medium |
| CN111783280A (en) * | 2020-06-10 | 2020-10-16 | 北京遥测技术研究所 | Single-pulse self-tracking design method based on logarithmic nonlinear detection |
| CN111783280B (en) * | 2020-06-10 | 2024-05-14 | 北京遥测技术研究所 | Single pulse self-tracking design method based on logarithmic non-linear detection |
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