CN104717168B - Orthogonal frequency division multiplexing (OFDM) ultra wide band system anti-multipath regular synchronization scheme - Google Patents
Orthogonal frequency division multiplexing (OFDM) ultra wide band system anti-multipath regular synchronization scheme Download PDFInfo
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Abstract
The present invention is directed to orthogonal frequency division multiplexing (OFDM) ultra wide band system, and complementary correlation properties based on leading Golay complementary sequences, research and design can resist the regular synchronization scheme of channel multi-path interference.First, using the training sequence of leading repetition, autocorrelation value is slided in the normalization for calculating continuous two windows, and the trailing edge based on relevant peaks carries out frame detection and determines thick timing position.And then, using the Golay complementary sequences structure inside training sequence, distinctive normalization separation maximal correlation computational methods are devised, and the multiple correlation peaks obtained are averaged to determine thin timing position.Emulation shows, under the CM1 multipath channel models of low signal-to-noise ratio, and the root-mean-square error of remaining timing offset can reach 10 after thin timing‑3The order of magnitude, arithmetic accuracy is higher, and can effectively resist multi-path jamming, while algorithm has relatively low complexity.
Description
Technical field
The present invention relates to OFDM (Othorgonal Frequency Division Multiplexing,
OFDM) ultra wide band (Ultra Wide Band, UWB) system can resist the regular synchronization scheme of multi-path jamming.For
60GHz OFDM radio ultra wide band systems as defined in IEEE802.15.3c standards are related using the complementation of leading Golay complementary sequences
Characteristic, devises the frame detection, thick timing and thin timing suitable for the system, so as to high-precision under a multipath fading channel
Detect symbol original position degree, OFDM demodulation is carried out so as to correct.
Background technology
The Technology of Ultra has the features such as power spectral density is low, transmission rate is high, anti-multipath jamming ability is strong,
Be mainly used in short distance high-speed radiocommunication, penetrate imaging, measurement in terms of.The IEEE802.15.3c marks proposed for 2009
Wireless Personal Network (WPAN) will definitely be used for, 60GHz radio frequency bands are operated mainly in, various countries can freely be used without license
Frequency range is about in 56GHz-66GHz scopes, and the message transmission rate supported is more than Gbit/s.Orthogonal frequency division multiplexi is with it
The advantages of availability of frequency spectrum is high, anti-symbol crosstalk ability strong, mitigating frequency-selective fading ability is strong is used as its physical layer modulation side
One of case.Standard defines system major parameter：Total number of sub-carriers is 512, is led including 336 information subcarriers, 16
Frequency subcarrier, 16 protection subcarriers, 3 direct current subcarriers and 141 null subcarriers.It is 64 that length is added after transmitting terminal IFFT
Cyclic prefix as protection interval, the OFDM symbol that composition length is 576.Start per frame as targeting sequencing, including frame synchronization
Sequence (SYNC), frame delimiter (SFD) and channel estimation sequence (CES), and they are by Gray (Golay) complementary series structure
Into as shown in Figure 1.
For high rate ultra wideband system, the orthogonality requirement of OFDM scheme sub-carriers is higher, to Timing Synchronization
Requirement it is also higher.If system timing is advanced and is no more than the length of cyclic prefix, the phase place of frequency data can be brought, is produced
The interference (ICI) of raw subcarrier with channel estimation, it is necessary to be compensated；If timing it is delayed, can cause simultaneously subcarrier interference with
More serious intersymbol interference (ISI), has a strong impact on systematic function.
Multidiameter fading channel is another key technical problem that OFDM wireless communication systems face.Multi-path jamming not only influences
Signal transmission quality, can also directly affect Timing Synchronization performance.Under Gaussian white noise channel, conventional timing synchronization algorithm is
It can reach good timing accuracy.But under the channel with multidiameter delay, due to timing position be energy it is most powerful without
It is the first footpath, often timing position is delayed and position ambiguity increases, and Timing Synchronization performance is drastically deteriorated.
The channel impulse response proposed in IEEE802.15.3c is the modification model based on S-V models, is shown below,
Wherein, δ () is dirac impulse function, and β δ (τ, φ) are line of sight component, and L is the number of cluster, KlIt is L clusters
The multipath component number of middle arrival, αK, l、τK, lAnd ωK, lIt is the complex amplitude, time delay and arrival bearing of each multipath component respectively
Angle, TlAnd θlIt is the time delay of every cluster and average arrival bearing angle.IEEE802.15.3c gives the channel mould under each channel circumstance
Shape parameter, 9 kinds of channel model CM1-CM9 have been divided according to different parameters, wherein the corresponding office of CM1 with CM2 channel models
Scene.
Golay complementary sequences have complementary autocorrelation performance, only just have nonzero value output when perfectly correlated, this is defeated
Go out is exactly channel response.This property of Golay complementary sequences determines its advantage insensitive to multipath channel.Golay complementary
Sequential structure is simple, and length is not required, therefore the length of the delay extension of channel is not limited, and can resist longer many
Footpath delay spread.
The content of the invention
The OFDM radio ultra wide band systems that the present invention is used for IEEE802.15.3c standards, utilize the mutual of Golay complementary sequences
Mend correlation properties, devise suitable for the system can anti-multipath regular synchronization scheme, realize under multidiameter fading channel
Accurate timing.
Technical scheme
Normalization is calculated using the Golay sequence of leading repetition and slides autocorrelation value, and frame is carried out based on related platform trailing edge
Detection and thick timing.Thin timing using leading Golay complementary sequences complementary autocorrelation performance, calculate can anti-multipath it is multiple
Self correlated peak, then the position of multiple correlation peaks is averaged.The high precision timing of feasible system of the present invention, while the program
With relatively low complexity.
Beneficial effects of the present invention
The present invention devise a kind of OFDM radio ultra wide band systems can anti-multipath regular synchronization scheme.The program has taken into account timing
Net synchronization capability and system implementation complexity, can be achieved the high precision timing under multidiameter fading channel, remaining timing offset are controlled
In very low range, that is, the demodulation performance of receiver is ensure that, system can be made correctly to recover initial data, reduced and be implemented as again
This, realizes that ultra-wideband communications receiver has actual directive significance to hardware.
Brief description of the drawings
Fig. 1 is preamble synchronization sequential structure figure
Fig. 2 (a) is that Golay sequence b128 calculates aperiodic autocorrelation result Rb
Fig. 2 (b) is that Golay sequence a128 calculates aperiodic autocorrelation result Ra
Fig. 2 (c) is RaWith RbSum
Autocorrelation value C is slided in the normalization for the correlation window a length of 128 that Fig. 3 (a) is calculated by frame detection-phasei
The normalization separation correlation D for the correlation window a length of 32 that Fig. 3 (b) is calculated by thin timing stagei
Fig. 4 is the false-alarm and false dismissal probability of frame detection under different thresholdings
Fig. 5 is the thick timing root-mean-square error (MSRE) under different multipath channel models
Fig. 6 is the thin timing root-mean-square error (MSRE) under different multipath channel models
Embodiment
The embodiment of the present invention is described further below in conjunction with accompanying drawing and by embodiment：
The present invention devises orthogonal frequency division multiplexing (OFDM) ultra wide band system anti-multipath regular synchronization scheme, it is characterised in that：We
Case comprises the following steps：
A. normalization is calculated based on the preamble synchronization sequence repeated and slides autocorrelation value Ci, and in this, as judgement amount, if
A fixed threshold value G, works as CiDuring less than G, confirm as detecting frame, order now corresponds to i=it, wherein i is sample index, itFor
Detect the position of frame；
B. it is more than i in itAnd less than itC is searched in the range of+MiMaximum, and the corresponding sample index of this maximum is remembered
For i=μ, then thick timing position is Pc=L- μ , wherein M are the length of a symbol, and L is the length of preamble synchronization sequence；
C. the preamble synchronization sequence based on reconstruct calculates normalization separation correlation Di, record all M in result of calculation
The corresponding sample index i of individual peak valuem, m=1,2 ..., M, and preceding M-1 peak is averagely arrived last peak
On be used as thin timing position Pf。
The preamble synchronization sequence repeated described in step a is Golay sequence b128 as defined in IEEE802.15.3c standards.
Autocorrelation value C is slided in normalization described in step aiCalculation formula be
Wherein piFor i-th of the sample value received, autocorrelation window length N is the length 128 of one section of Golay sequence.
The preamble synchronization sequence reconstructed described in step c, is the low order Golay complementary separated by high-order Golay sequence
Sequence, its structure is
Wherein, b128 is the Golay sequence that length is 128, and a32 and b32 is the Golay complementary sequences that length is 32.
Described in step c normalization separation correlation calculation formula be
Wherein piFor i-th of the sample value received, autocorrelation window length N is 32.
Thin timing position P described in step cfDetermination method be
Wherein, M is the quantity of relevant peaks, imFor the sample index corresponding to peak.
Embodiment
The present invention is applied in the OFDM radio ultra wide band systems of IEEE802.15.3c standards, based on Matlab/Simulink pairs
The system is emulated.
As shown in Fig. 2 (a) (b) (c), the autocorrelation sidelobe of single Golay sequence is larger, and the non-week of Golay complementary sequences
Phase auto-correlation is zero due to complementary cancellation, all secondary lobes.This preferable complementary autocorrelation performance of Golay complementary sequences, it is non-
It is very suitable for high precision timing synchronous.
Fig. 3 (a) show the oscillogram that autocorrelation value is slided in frame detection with the normalization that thick timing stage is calculated.Can be with
Find out, when correlation window length is 128, leading Part I frame synchronization sequence (SYNC) and Part II frame delimiter (SFD)
Between significantly decrease edge.Fig. 3 (b) show the oscillogram for the separation autocorrelation value that thin timing stage is calculated, and can see
Go out correlation window length for 32 when, produce a sharp relevant peaks every 64 sample values, can produce multiple relevant peaks altogether.
Fig. 4 show signal to noise ratio 0dB, CM2 channel, associated window it is a length of 128 when, the corresponding frame detection of different threshold value G is empty
Alert and false dismissal probability, it can be seen that false drop rate is minimum when thresholding G takes 0.14~0.16.
Fig. 5 show thick timing root-mean-square error (MSRE) curve under different channels model.As can be seen that Gaussian channel
Under multipath channel CM1, the MSRE similar natures of thick timing, and under CM2 channels, the MSRE of thick timing is larger, and with letter
Make an uproar than increase, MSRE is gradually stable within 5 sample values.
Fig. 6 show thick timing root-mean-square error (MSRE) curve under different channels model.It can be seen that 14dB's
Under Gaussian channel and CM1 channels, MSRE is up to 10-3The order of magnitude, and the MSRE under CM2 channels also can reach 10-2The order of magnitude.
This example demonstrates that, by above-mentioned emulation, regular synchronization scheme proposed by the invention can effectively resist multipath
Interference, can be achieved the high precision timing to receiving symbol.
Claims (4)
1. orthogonal frequency division multiplexing (OFDM) ultra wide band system anti-multipath time synchronization method, it is characterised in that：This method comprises the following steps：
A. normalization is calculated based on the preamble synchronization sequence repeated and slides autocorrelation value Ci, and in this, as judgement amount, set one
Limit value G, works as CiDuring less than G, confirm as detecting frame, order now corresponds to i=it, wherein i is sample index, itTo detect
The position of frame；
B. it is more than i in itAnd less than itC is searched in the range of+MiMaximum, and the corresponding sample index of this maximum is designated as i
=μ, then thick timing position is Pc=L- μ, wherein M are the length of a symbol, and L is the length of preamble synchronization sequence；
C. the preamble synchronization sequence based on reconstruct calculates normalization separation correlation Di, record all M peak values in result of calculation
Corresponding sample index im, m=1,2 ..., M, and using preceding M-1 peak averagely on last peak as
Thin timing position Pf；
D. the preamble synchronization sequence of the reconstruct, is the low order Golay complementary sequences separated by high-order Golay sequence, and it is tied
Structure is
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Wherein, b128 is the Golay sequence that length is 128, and a32 and b32 is the Golay complementary sequences that length is 32；
E. the calculation formula of the normalization separation correlation is
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Wherein piFor i-th of the sample value received, autocorrelation window length N is 32.
2. orthogonal frequency division multiplexing (OFDM) ultra wide band system anti-multipath time synchronization method according to claim 1, it is characterised in that：
The preamble synchronization sequence repeated described in step a is Golay sequence b128 as defined in IEEE 802.15.3c standards.
3. orthogonal frequency division multiplexing (OFDM) ultra wide band system anti-multipath time synchronization method according to claim 1, it is characterised in that：
Autocorrelation value C is slided in normalization described in step aiCalculation formula be
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Wherein piFor i-th of the sample value received, autocorrelation window length N is the length 128 of one section of Golay sequence.
4. orthogonal frequency division multiplexing (OFDM) ultra wide band system anti-multipath time synchronization method according to claim 1, it is characterised in that：
Thin timing position P described in step cfDetermination method be
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Wherein, M is the quantity of relevant peaks, imFor the sample index corresponding to peak.
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| CN107360624B (en) * | 2017-08-07 | 2020-08-18 | 西安交通大学 | Smooth autocorrelation timing coarse synchronization method based on multi-segment repeated leader sequence |
| CN110944384B (en) * | 2019-12-09 | 2020-12-15 | 中国电子科技集团公司第五十四研究所 | Indoor and outdoor high-precision positioning and communication integrated method |
| CN113114601B (en) * | 2021-04-06 | 2022-03-18 | 上海纵行企业发展有限公司 | Receiver based on M-FSK modulation and receiving method thereof |
| CN115278876B (en) * | 2022-09-19 | 2022-12-09 | 四川创智联恒科技有限公司 | Method for co-positioning between 5G network and UWB |
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| CN101447962A (en) * | 2007-11-27 | 2009-06-03 | 华为技术有限公司 | Method, device and synchronous system for sending and receiving synchronous information |
| CN102055708A (en) * | 2009-11-09 | 2011-05-11 | 南开大学 | Timing synchronization scheme of multi-band orthogonal frequency division multiplexing (OFDM) ultra wide-band system |
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| CN100576834C (en) * | 2003-03-28 | 2009-12-30 | 英特尔公司 | The method and apparatus that is used for the OFDM timing synchronization |
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|---|---|---|---|---|
| CN101447962A (en) * | 2007-11-27 | 2009-06-03 | 华为技术有限公司 | Method, device and synchronous system for sending and receiving synchronous information |
| CN102055708A (en) * | 2009-11-09 | 2011-05-11 | 南开大学 | Timing synchronization scheme of multi-band orthogonal frequency division multiplexing (OFDM) ultra wide-band system |
Non-Patent Citations (1)
| Title |
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| Golay complementary pair aided time synchronization method for OFDM systems;Luo Zhi-nian et.al;《Communication Technology (ICCT), 2012 IEEE 14th International Conference on》;20121111;第166-170页 * |
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