CN105024799B - A kind of band limit timing restoration methods based on p rank squares - Google Patents
A kind of band limit timing restoration methods based on p rank squares Download PDFInfo
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Abstract
The present invention relates to a kind of band based on p rank squares to limit timing restoration methods, and this method calculates Timing Error Detection output valve, wherein p in phase-locked loop is fed back, using the p power of signal modulus value>0 is variable element, and the method for the present invention can be applicable in timing recovery loop, obtains more preferable residual timing error jitter performance, and the normalized mean squared error performance of the method for the present invention Timed Recovery is limited close to theoretical carat Metro under awgn channel.The method of the present invention is suitable for the small Bandwidth-Constrained communication system of roll-off factor, is applicable to improve the satellite communication system of the availability of frequency spectrum.
Description
Technical field
The present invention relates to digital wireless communication transmission technique field, more particularly to a kind of band limit system based on p rank squares is determined
When restoration methods.
Background technology
In satellite communication system, it is often necessary to improve the frequency spectrum of signal to sending signal progress root raised cosine shaping,
Reduce the interference to adjacent frequency band., it is necessary to which recovery is timed to sampled signal obtains accurately modulation symbol in digital receiver
Number.Timing recovery algorithm is broadly divided into two class of data householder method and non-data-aided method.It is difficult to obtain before Timing Synchronization
Pilot data is obtained, therefore more often uses unbound nucleus timing method.Non-data-aided method can be divided into preceding to timing and feedback again
Periodically two class method.Forward direction timing method is suitable for the communication system of burst transfer, and feeds back timing method and be suitable for what is continuously transmitted
Communication system.
Document " F.M.Gardner, A BPSK/QPSK timing-error detector for sampled
In receivers, IEEE Trans.Commun., vol.COM-34, pp.423-429, May 1986. ", determined based on Gardner
When error detecting algorithm (GA) feedback phase-locked loop timing recovery method be a kind of blind synchronization method of unbound nucleus, it is fixed
Shi Xingneng is used widely from the influence of carrier deviation in the communication system continuously transmitted.If receive signal to be expressed as
rk=Ik+j·Qk, the Timing Error Detection output e of the algorithmk,GAIt is expressed as：
Wherein, rk、rk-1/2" two edge point " and " intermediate point " of the receiver in 2 times of data symbol rates, Re are represented respectively
{ } represents to seek the real part of complex values.Based on this algorithm, scholar Gappmair and Lim etc. respectively document " W.Gappmair,
S.Cioni,G.E.Corazza,and O.Koudelka,Extended Gardner Detector for Improved
Symbol-Timing Recovery of M-PSK Signals,IEEE Trans.Commun.,vol.54,pp.1923–
1927, Nov.2006. " and " D.Lim, 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. it have studied the improvement project of Timing Error Detection algorithm in document.But this kind of timing based on GA algorithms
Method is only applicable in the communication system using larger shaping roll-off factor.
With high definition, ultra high-definition DTV direct broadcasting satellite, and the multimedia internet high speed biography based on satellite communication
Defeated fast development, the bandwidth resources of communication satellite coverage are more and more nervous.It is wide in the second generation satellite digital video of extension
In broadcast system (DVB-S2X), band system band efficiency is improved close to 0 root raised cosine forming filter using the shaping factor.
At this time, traditional timing recovery method poor-performing based on GA algorithms,
The content of the invention
It is an object of the invention to overcome the deficiencies of the prior art and provide a kind of band limit timing based on p rank squares is extensive
Compound method, this method calculate Timing Error Detection output valve, wherein p in phase-locked loop is fed back, using the p power of signal modulus value
>0, more preferable residual timing error jitter performance can be obtained.
The above-mentioned purpose of the present invention is achieved by following technical solution：
A kind of band limit timing restoration methods based on p rank squares, mainly include the following steps：
Step (1), by from the sampled signal r of external receptionnFiltering interpolation is carried out using interpolation filter, obtains 2 times
The signal data of character rate, is denoted as yk, wherein, interpolation filter is by interpolation nodes mkAnd relative timing deviation ukControl carries out
Interpolation fitting, mk、ukInitial value take positive integer for 0, k；
Step (2), the signal data for obtaining step (1) carry out matched filtering using matched filter, are filtered
Data afterwards, are denoted as xk-1、xk-1/2、xk, wherein xk、xk-1Represent both sides point sampling data, xk-1/2Represent intermediate point sampled data,
Wherein, k takes positive integer；At the same time by xk-1、xkOutput, the output data result as Timed Recovery；
Step (3), calculate filtered data xk、xk-1/2、xk-1The p power non-linear values of modulus value are
Xk=| xk|p, Xk-1/2=| xk-1/2|p, Xk-1=| xk-1|p
Wherein：P is positive number；
Step (4), according to filtered data xk、xk-1/2、xk-1The p power non-linear value of modulus value calculates timing error inspection
Survey the output quantity e of devicek
Step (5), when being realized using first-order filtering loop, loop filter is used to Timing Error Detection output quantity ek
Carry out loop filtering, control word Wk+1Update method
Wk+1=Wk+γek
Wherein, W0=1/Ns, NsFor the ratio in the data cycle before interpolation filter and after interpolation filter, control word Wk+1
It is progressive step by step；；The calculation formula of γ isFor the detection of Timing Error Detector
Gain,To differentiate, τ be channel introduce unknown timing error deviation, BLFor the bandwidth of loop filter, TsFor data
The cycle of symbol；
Step (6), the control word W by renewalk+1Use interpolation controller extraction interpolation nodes mk+1With relative timing deviation
uk+1；
Step (7), return to step (one), make k=k+1, repeat step (one) to step (6), completes the docking collection of letters number
Timed Recovery.
Timing restoration methods are limited in a kind of above-mentioned band based on p rank squares, when such as being realized using second-order filter loop, institute
The control word W statedk+1Update method is
Wk+1=Wk+K1ek+Lk+1
Lk+1=Lk+K2ek
Wherein, W0=1/Ns, NsFor the ratio in the data cycle before interpolation filter and after interpolation filter, coefficient is updatedUpdate coefficient
The present invention has the advantages that compared with prior art：
(1) band limit timing restoration methods of the present invention based on p rank squares, suitable for the small situation of roll-off factor, relatively
System is limited in the satellite communication band that traditional timing recovery method is more suitable for needing to improve the availability of frequency spectrum.
(2) band limit timing restoration methods of the present invention based on p rank squares, the amplitude processing based on signal, its timing are same
For the performance of step from the influence of carrier deviation, the performance of its Timing Synchronization is unrelated with modulation system；
(3) band limit timing restoration methods of the present invention based on p rank squares, are timed using the p power of signal modulus value
Error-detecting, detection gain increase as p increases；
(4) band limit timing restoration methods of the present invention based on p rank squares, the normalization of Timed Recovery is equal under awgn channel
Square error performance close to theoretical carat Metro limit, timing jitter variance after Timed Recovery under low signal-to-noise ratio reduce with p and
Reduce.
Brief description of the drawings
Fig. 1 is the phase-locked loop composition frame chart that band of the present invention based on p rank squares limits timing restoration methods；
Fig. 2 is that band of the present invention based on p rank squares limits S of the timing restoration methods in different p, different α with GA algorithms
Curve；
Fig. 3 is that band of the present invention based on p rank squares limits timing restoration methods in different p, S curve during α=0.05；
Fig. 4 be band limit system bright timing recovery method of this hair based on p rank squares in different p, S curve during α=0.05 is oblique
Rate；
Fig. 5 receives for timing jitter during the timing acquisition of the band limit timing restoration methods of the invention based on p rank squares
Hold back curve；
Fig. 6 is timing jitter mean square error (MSE) property that band of the present invention based on p rank squares limits timing restoration methods
Energy；
Embodiment
The present invention is described in further detail with specific embodiment below in conjunction with the accompanying drawings：
A kind of band limit timing restoration methods based on p rank squares, it is characterised in that include the following steps：
Step (1), by from the sampled signal r of external receptionnFiltering interpolation is carried out using interpolation filter, obtains 2 times
The signal data of character rate, is denoted as yk, wherein, interpolation filter is by interpolation nodes mkAnd relative timing deviation ukControl carries out
Interpolation fitting, mk、ukInitial value take positive integer for 0, k；
Step (2), the signal data for obtaining step (1) carry out matched filtering using matched filter, are filtered
Data afterwards, are denoted as xk-1、xk-1/2、xk, wherein xk、xk-1Represent both sides point sampling data, xk-1/2Represent intermediate point sampled data,
Wherein, k takes positive integer；At the same time by xk-1、xkOutput, the output data result as Timed Recovery；
Step (3), calculate filtered data xk、xk-1/2、xk-1The p power non-linear values of modulus value are
Xk=| xk|p, Xk-1/2=| xk-1/2|p, Xk-1=| xk-1|p
Wherein：P is positive number；
Step (4), according to filtered data xk、xk-1/2、xk-1The p power non-linear value of modulus value calculates timing error inspection
Survey the output quantity e of devicek
Step (5), when being realized using first-order filtering loop, loop filter is used to Timing Error Detection output quantity ek
Carry out loop filtering, control word Wk+1Update method
Wk+1=Wk+γek
Wherein, WkInitial value W0=1/Ns, NsFor before interpolation filter and interpolation filter after the data cycle ratio,
Control word Wk+1It is progressive step by step；；The calculation formula of γ is For Timing Error Detection
The detection gain of device,To differentiate, τ be channel introduce unknown timing error deviation, BLFor the bandwidth of loop filter,
TsFor the cycle of data symbol；
Step (6), the control word W by renewalk+1Use interpolation controller extraction interpolation nodes mk+1With relative timing deviation
uk+1；
Step (7), return to step (one), make k=k+1, repeat step (one) to step (6), completes the docking collection of letters number
Timed Recovery.
In above-mentioned steps (five), when such as being realized using second-order filter loop, the control word Wk+1Update method is
Wk+1=Wk+K1ek+Lk+1
Lk+1=Lk+K2ek
Wherein, L is madekInitial value L0=0, WkInitial value W0=1/Ns, NsFor before interpolation filter and after interpolation filter
The ratio in data cycle, Lk+1And Wk+1It is progressive step by step, update coefficientUpdate coefficient
Embodiment 1
The handling result of the timing recovery method of the prior art He timing recovery method of the present invention is compared.
(1) open loop S curve is compared with slope
Data use QPSK modulation systems, under awgn channel environment, to existing GA algorithms and this under the conditions of SNR=10dB
Band limit timing restoration methods detection characteristic of the invention based on p rank squares carries out emulation comparison, simulation result such as Fig. 2, Fig. 3, Fig. 4
It is shown, by can be seen that in Fig. 2：GA algorithms reduce with roll-off factor α, and S curve tends towards stability, and peak value diminishes, and the present invention is fixed
When restoration methods work as p=1, when 2, as roll-off factor α reduces, S curve tends to be sharp, and peak value becomes larger.By that can be seen in Fig. 3
Go out：Keep α=0.05 constant, timing recovery method of the present invention is in p=1,1.5,2,2.5,3,3.5,4 as p increases S curve
Tend to be sharp, peak value becomes larger.The slope of timing recovery method of the present invention S curve in p=1,1.5,2,2.5,3,3.5,4 is as schemed
Shown in 4, slope increases as p increases as seen from the figure.
(2) timing jitter emulation is compared under tracking mode
Data are modulated using QPSK, and frequency-locked loop uses first-order filtering loop, in the case of not plus noise, keep loop
Normalize bandwidth BLTs=5 × 10-3It is constant, it can be seen from Fig. 5 simulation results in roll-off factor α=0.05, using this hair
The convergence rate of the convergence rate of bright timing recovery method and GA algorithms in larger roll-off factor α=0.25 approaches, can by figure
Know, the shake smaller after timing recovery method convergence of the present invention.
Data use QPSK, and under the conditions of awgn channel, frequency-locked loop uses first-order filtering loop, keeps roll-off factor α
=0.05, loop normalization bandwidth BLTs=5 × 10-3Constant, signal-to-noise ratio is respectively set to SNR=5dB~30dB, is imitated by Fig. 6
True result can be seen that new algorithm close to theoretical amendment carat Metro limit (MCRB), and GA algorithm detector timing properties bs are very poor.Changing
Become p=1, when 2,3, as p increases, detector timing properties b during low signal-to-noise ratio is deteriorated.Meanwhile when keep p=2 it is constant, modulation system
For 8PSK signals when, the detector timing properties b and QPSK signal timing performances of the method for the present invention approach, illustrate this algorithm performance with modulation
Mode is unrelated.
The above, is only the optimal embodiment of the present invention, but protection scope of the present invention is not limited thereto,
Any one skilled in the art the invention discloses technical scope in, the change or replacement that can readily occur in,
It should be covered by the protection scope of the present invention.
The content not being described in detail in description of the invention belongs to the known technology of professional and technical personnel in the field.
Claims (2)
1. a kind of band limit timing restoration methods based on p rank squares, it is characterised in that include the following steps：
Step (1), by from the sampled signal r of external receptionnFiltering interpolation is carried out using interpolation filter, obtains 2 times of symbols
The signal data of speed, is denoted as yk, wherein, interpolation filter is by interpolation nodes mkAnd relative timing deviation ukControl into row interpolation
Fitting, mk、ukInitial value take positive integer for 0, k；
Step (2), the signal data for obtaining step (1) carry out matched filtering using matched filter, obtain filtered
Data, are denoted as xk-1、xk-1/2、xk, wherein xk、xk-1Represent both sides point sampling data, xk-1/2Represent intermediate point sampled data, its
In, k takes positive integer；At the same time by xk-1、xkOutput, the output data result as Timed Recovery；
Step (3), calculate filtered data xk-1、xk-1/2、xkThe p power non-linear values of modulus value are
Xk=| xk|p, Xk-1/2=| xk-1/2|p, Xk-1=| xk-1|p
Wherein：P is positive number；
Step (4), according to filtered data xk-1、xk-1/2、xkThe p power non-linear value of modulus value calculates Timing Error Detector
Output quantity ek
ek=Xk-1/2(Xk-Xk-1)=| xk-1/2|p(|xk|p-|xk-1|p)
Step (5), when being realized using first-order filtering loop, to Timing Error Detection output quantity ekRing is carried out using loop filter
Road filters, control word Wk+1Update method
Wk+1=Wk+γek
Wherein, W0=1/Ns, NsFor the ratio in the data cycle before interpolation filter and after interpolation filter, control word Wk+1Step by step
It is progressive；The calculation formula of γ isFor the detection gain of Timing Error Detector,To differentiate, τ be channel introduce unknown timing error deviation, BLFor the bandwidth of loop filter, TsFor data symbol
Cycle；
Step (6), the control word W by renewalk+1Use interpolation controller extraction interpolation nodes mk+1With relative timing deviation uk+1；
Step (7), return to step (one), make k=k+1, repeat step (one) to step (6), completes determining for the docking collection of letters number
Shi Huifu.
A kind of 2. band limit timing restoration methods based on p rank squares according to claim 1, it is characterised in that：Using
When second-order filter loop is realized, the control word Wk+1Update method is
Wk+1=Wk+K1ek+Lk+1
Lk+1=Lk+K2ek
Wherein, L0=0, W0=1/Ns, NsFor the ratio in the data cycle before interpolation filter and after interpolation filter, coefficient is updatedUpdate coefficient
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| CN103457680A (en) * | 2013-08-20 | 2013-12-18 | 重庆邮电大学 | Satellite communication timing synchronization error detection method based on full-digital receiving |
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