CN107276940A - Time synchronization method, device and system - Google Patents

Abstract

The invention provides a kind of time synchronization method, including：Signal and local midamble code execution auto-correlation computation will be received using sliding window method, to obtain multiple autocorrelation results, wherein the reception signal is the time-frequency two-dimensional overlapped signal from transmitting terminal and including training sequence and data based on midamble code, and wherein training sequence frequency range is more than the power spectral density of data bandwidth and training sequence and is less than the power spectral densities of data；And autocorrelation peak is determined from the plurality of autocorrelation result, using the position of the autocorrelation peak as the original position of the midamble code, the original position of the midamble code is used for the timing for determining the reception signal.By designing LAS code training sequences in a communications system, Timing Synchronization is done using the LAS codes in signal reception processing.When doing Timing Synchronization using LAS codes, by rationally setting threshold values accurately to find training symbol position, timing precision is improved, is that follow-up carrier synchronization, channel estimation process and decoding process are laid a good foundation, reduce the bit error rate of system.

Description

Time synchronization method, device and system

Technical field

The present invention relates generally to wireless communication system, more particularly to time synchronization method, device and system.

Background technology

Cordless communication network is widely deployed to provide the various communication services such as voice, video, grouped data, information receiving, broadcast.These wireless networks can support the multi-access network of multiple users by sharing available Internet resources.The example of this kind of multi-access network includes CDMA (CDMA) network, time division multiple acess (TDMA) network, frequency division multiple access (FDMA) network, orthogonal FDMA (OFDMA) networks and Single Carrier Frequency Division Multiple Access (SC-FDMA) network.

With global mobile communication constantly enhanced demand, the frequency resource of radio communication is more nervous.Therefore, in addition to the wireless communication system of utilization rate is composed based on TDM (time division multiplexing), FDM (frequency division multiplexing) above-mentioned conventional highfrequency, it is also proposed that there is the more radical communication plan of more high usage for frequency spectrum.

Exactly such a scheme for improving system spectral efficiency of overlapped time division multiplexing (Overlapped Time Division Multiplexing, OvTDM) system., not only need not be mutually isolated between symbol in OvTDM systems, and can have very strong mutual overlapping.In other words, the overlapping between OvTDM systems are by being artificially induced symbol, transmits data sequence in time-domain parallel using multiple symbols, the availability of frequency spectrum greatly improved.

Overlapping frequency division multiplexing (Overlapped Frequency Division Multiplexing, OvFDM) system is the scheme that another improves system spectral efficiency.Can have more stronger than orthogonal frequency division multiplex OFDM overlapping in OvFDM systems, between sub-carrier band.By overlapping degree higher between each sub-band in frequency domain, the availability of frequency spectrum is further increased on the basis of ofdm system.

Although there is corresponding reception demodulation scheme to exclude overlapping brought interference of the signal in time domain or frequency domain for above-mentioned OvTDM systems and OvFDM systems, the reception greatly improved still to signal of the availability of frequency spectrum proposes requirements at the higher level.

Therefore, OvTDM systems and OvFDM systems need the network insertion scheme of higher performance.And the m-sequence Timing Synchronization mode that existing communication system is used can not meet demand.

The content of the invention

The brief overview of one or more aspects given below is to provide to the basic comprehension in terms of these.This summarizes the extensive overview of the not all aspect contemplated, and is both not intended to identify the key or decisive key elements of all aspects also non-scope attempted to define in terms of any or all.Its unique purpose is that some concepts that provide one or more aspects in simplified form think the sequence of more detailed description given later.

It is an object of the invention to, Timing Synchronization is done using m-sequence for existing communication system, auto-correlation and cross correlation are poor, correlation peak distribution is caused relatively to be concentrated, training symbol original position can not be exactly found, the relatively low defect of timing precision is caused there is provided a kind of time synchronization method and device, to solve the above problems.

According to an aspect of the present invention there is provided a kind of time synchronization method, including：

Signal and local midamble code execution auto-correlation computation will be received using sliding window method, to obtain multiple autocorrelation results, wherein the reception signal is the time-frequency two-dimensional overlapped signal from transmitting terminal and including training sequence and data based on midamble code, and wherein training sequence frequency range is more than the power spectral density of data bandwidth and training sequence and is less than the power spectral densities of data；And

Autocorrelation peak is determined from the plurality of autocorrelation result, using the position of the autocorrelation peak as the original position of the midamble code, the original position of the midamble code is used for the timing for determining the reception signal.

In one example, the midamble code includes m-sequence, Golomb codes, CAN codes or LAS codes.

In one example, 5 times, 10 times, 15 times or more of the training sequence frequency range more than data bandwidth.

In one example, this will receive signal and local midamble code execution auto-correlation computation using sliding window method and include：

Length using the length of the midamble code as window takes window to the reception signal, the signal section that receives in current window is performed into auto-correlation computation with local midamble code, to obtain an autocorrelation result；

The window is slided backward to take window again to the reception signal, the signal section that receives in current window auto-correlation computation is performed into local midamble code again, to obtain another autocorrelation result；And

Repeat sliding window and the step of signal section performs auto-correlation computation with local LAS will be received in window, until the auto-correlation processing that whole length receives signal is completed, to obtain the plurality of autocorrelation result.

In one example, the training sequence includes a midamble code, wherein determining that autocorrelation peak includes from the plurality of autocorrelation result：

Only one autocorrelation peak is determined from the plurality of autocorrelation result.

In one example, determine that only one autocorrelation peak includes from the plurality of autocorrelation result：

It regard more than the first of predetermined threshold autocorrelation result as the only one autocorrelation peak.

In one example, a midamble code is LAS short codes.

In one example, the training sequence includes two midamble codes of identical, wherein determining that autocorrelation peak includes from the plurality of autocorrelation result：

Two autocorrelation peaks are determined from the plurality of autocorrelation result；And

Determined from two autocorrelation peaks with the associated peak value of preceding midamble code, using with this in the position of the associated peak value of preceding midamble code as this in the original position of preceding midamble code, the timing of the original position for determining the reception signal in preceding midamble code.

In one example, two midamble codes are LAS short codes.

In one example, the training sequence includes：[0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN, wherein [0]_SNFor 0 sequence that length is SN, [X_las]_SNLAS short codes for being SN for length, wherein determining to include with the peak value associated in preceding LAS code-phases from two autocorrelation peaks：

If the gap length between two autocorrelation peaks is 2*SN, the peak value that first autocorrelation peak in two autocorrelation peaks is defined as associating with preceding LAS code-phases,

If the gap length between two autocorrelation peaks is more than 2*SN, the peak value that second autocorrelation peak in two autocorrelation peaks is defined as associating with preceding LAS code-phases.

In one example, determine that two autocorrelation peaks include from the plurality of autocorrelation result：

Two autocorrelation result subsets of the integrated distribution more than predetermined threshold are determined from the plurality of autocorrelation result；And

Using first in each autocorrelation result subset autocorrelation result for exceeding the threshold value as the autocorrelation peak, so as to obtain two autocorrelation peaks.

According to another aspect of the present invention there is provided a kind of timing synchronization device, including：

Transmitting terminal and receiving terminal, transmitting terminal send time-frequency two-dimensional overlapped signal to receiving terminal；Generation receives signal after receiving terminal is received；

Autocorrelation calculation unit, for signal and local midamble code execution auto-correlation computation will to be received using sliding window method, to obtain multiple autocorrelation results, wherein the reception signal includes training sequence and data based on midamble code, and wherein training sequence frequency range is more than power spectral density of the power spectral density less than data of data bandwidth and training sequence；And

Peak value judging unit, for determining autocorrelation peak from the plurality of autocorrelation result, using the position of the autocorrelation peak as the original position of the midamble code, the original position of the midamble code is used for the timing for determining the reception signal.

In one example, the midamble code includes m-sequence, Golomb codes, CAN codes or LAS codes.

In one example, 5 times, 10 times, 15 times or more of the training sequence frequency range more than data bandwidth.

In one example, the autocorrelation calculation unit is further used for：

Length using the length of the midamble code as window takes window to the reception signal, the signal section that receives in current window is performed into auto-correlation computation with local midamble code, to obtain an autocorrelation result；

The window is slided backward to take window again to the reception signal, the signal section that receives in current window auto-correlation computation is performed into local midamble code again, to obtain another autocorrelation result；And

Repeat sliding window and the step of signal section performs auto-correlation computation with local LAS will be received in window, until the auto-correlation processing that whole length receives signal is completed, to obtain the plurality of autocorrelation result.

In one example, the training sequence includes a midamble code, and the peak value judging unit is further used for from the plurality of autocorrelation result determining only one autocorrelation peak.

In one example, the peak value judging unit is further used for regarding more than the first of predetermined threshold autocorrelation result as the only one autocorrelation peak.

In one example, a midamble code is LAS short codes.

In one example, the training sequence includes two midamble codes of identical, and the wherein peak value judging unit is further used for：

Two autocorrelation peaks are determined from the plurality of autocorrelation result；And

Determined from two autocorrelation peaks with the associated peak value of preceding midamble code, using with this in the position of the associated peak value of preceding midamble code as this in the original position of preceding midamble code, the timing of the original position for determining the reception signal in preceding midamble code.

In one example, two midamble codes are LAS short codes.

In one example, the training sequence includes：[0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN, wherein [0]_SNFor 0 sequence that length is SN, [X_las]_SNThe LAS short codes for being SN for length, the peak value judging unit is further used for：

If the gap length between two autocorrelation peaks is 2*SN, the peak value that first autocorrelation peak in two autocorrelation peaks is defined as associating with preceding LAS code-phases,

If the gap length between two autocorrelation peaks is more than 2*SN, the peak value that second autocorrelation peak in two autocorrelation peaks is defined as associating with preceding LAS code-phases.

In one example, the peak value judging unit is further used for：

Two autocorrelation result subsets of the integrated distribution more than predetermined threshold are determined from the plurality of autocorrelation result；And

Using first in each autocorrelation result subset autocorrelation result for exceeding the threshold value as the autocorrelation peak, so as to obtain two autocorrelation peaks.

The present invention has following beneficial effect：The present invention by designing LAS code training sequences in a communications system, in origin it is preferable impulse function using LAS codes auto-correlation function, it is zero everywhere beyond origin, and cross-correlation function is zero characteristic everywhere, and Timing Synchronization is done using the LAS codes in signal reception processing.When doing Timing Synchronization using LAS codes, by rationally setting threshold values accurately to find training symbol position, timing precision is improved, is that follow-up carrier synchronization, channel estimation process and decoding process are laid a good foundation, reduce the bit error rate of whole system.

Brief description of the drawings

After the detailed description of embodiment of the disclosure is read in conjunction with the following drawings, the features described above and advantage of the present invention better understood when.In the accompanying drawings, each component is not necessarily drawn to scale, and the component with similar correlation properties or feature may have same or like reference.

Fig. 1 shows the block diagram of the transmitting terminal modulation module of OvTDM systems；

Fig. 2 shows the block diagram of the signal pre-processing module of the receiving terminal of OvTDM systems；

Fig. 3 shows the block diagram of the receiving terminal sequence detection module of OvTDM systems；

Fig. 4 shows the modulation module block diagram of the transmitting terminal of OvFDM systems；

Fig. 5 shows the block diagram of the signal pre-processing module of the receiving terminal of OvFDM systems；

Fig. 6 shows the block diagram of the signal detection module of the receiving terminal of OvFDM systems；

Fig. 7 shows the autocorrelation performance of M sequence；

Fig. 8 shows the autocorrelation performance of LAS codes；

Fig. 9 shows the distribution map of the autocorrelation result of Timing Synchronization；

Figure 10 shows the schematic diagram for detecting the training sequence under two peak value situations；

Figure 11 shows the block diagram of the time synchronization unit of receiving terminal according to an aspect of the present invention；

Figure 12 shows the flow chart of time synchronization method according to an aspect of the present invention；

Figure 13 shows the block diagram of carrier synchronization unit according to an aspect of the present invention；

Figure 14 shows the flow chart of carrier synchronization method according to an aspect of the present invention；

Figure 15 shows the flow chart of carrier synchronization method according to an aspect of the present invention；

Figure 16 shows the arrangement schematic diagram of multipath channel；

Figure 17 shows training sequence according to an aspect of the present invention and the frequency range and power spectral density graph of a relation of data；

Figure 18 shows two carrier signals according to an aspect of the present invention while spectrum diagram when sending data；

Figure 19 is OvHDM system schematic.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.Note, the aspects described below in conjunction with the drawings and specific embodiments is only exemplary, and be understood not to carry out any limitation to protection scope of the present invention.

Except applying in OvTDM and OvFDM systems, all technologies described herein are also widely applied in actual GSM, such as TD-LTE, TD-SCDMA system, be also widely applied to satellite communication, microwave horizon communication, scatter communication, atmosphere optic communication, infrared communication with aquatic any wireless communication system such as communicate.Term " network " and " system " are often used interchangeably.

Mobile communication continue to develop and emerging in an endless stream for new business proposes higher and higher requirement to message transmission rate, and the frequency resource of mobile communication is extremely limited, how to realize that the high-speed transfer of data turns into the major issue that current mobile communication technology faces using limited frequency resource

Above-mentioned OvTDM and OvFDM systems are exactly this can to greatly improve the solution of the availability of frequency spectrum.OvTDM systems are briefly described below sends and receives process.

OvTDM systems are using multiple symbols in time-domain transmitting data in parallel sequence.Multiple symbols transmission signal overlapped in time-domain is formed in transmitting terminal, receiving terminal is according to transmission data sequence and transmits the one-to-one relationship between data sequence time waveform, the docking collection of letters number carries out being detected by data sequence in time-domain.OvTDM systems actively using these it is overlapping be allowed to produce coding bound relation, so that the spectrum efficiency of system is greatly improved.

Fig. 1 shows the block diagram of the transmitting terminal modulation module of OvTDM systems.Transmitting terminal modulation module 100 may include digital waveform generating unit 110, shifting deposit unit 120, multiplication unit 130 and adder unit 140.

First, design first modulated signal envelope waveform h (t) that generation sends signal in a digital manner by digital waveform generating unit 110, the envelope waveform h (t) is carried out special time displacement by shifting deposit unit 120, form the envelope waveform h (t-i × Δ T) of other each moment modulated signal, multiplication unit 130 is by the parallel symbol x to be sent_iBe multiplied with the envelope waveform h (t-i × Δ T) at corresponding moment, obtain each moment it is modulated after signal waveform x to be sent_ih(t-i×ΔT).Each waveform to be sent formed is overlapped by adder unit 140, forms transmission signal waveform.

The receiving terminal of OvTDM systems is broadly divided into signal pre-processing module 200 and sequence detection module 300.Fig. 2 shows the block diagram of the signal pre-processing module 200 of the receiving terminal of OvTDM systems.Signal pre-processing module is used to aid in the synchronous reception digital signal sequences for forming each frame in, as illustrated, the signal pre-processing module may include synchronization unit 210, channel estimating unit 220 and digitlization processing unit 230.

Synchronization unit 210 is used to dock the collection of letters number in time domain formation sign synchronization, to keep synchronous regime with system, mainly includes Timing Synchronization and carrier synchronization.Synchronously complete the rear docking of channel estimating unit 220 collection of letters number and do channel estimation, for estimating the parameter of actual transmission channel.Digitized processing unit 230 is used to be digitized processing to the reception signal of each frame in, so as to form the reception digital signal sequences that suitable Sequence Detection part carries out Sequence Detection.

After pre-processing, the docking collection of letters number a Sequence Detection can be carried out in sequence detection module 300, the waveform received is cut according to waveform transmission time interval and row decoding is entered to the waveform after cutting according to certain decoding algorithm.Fig. 3 shows the block diagram of the receiving terminal sequence detection module of OvTDM systems.As illustrated, sequence detection module 300 may include analysis memory cell 310, comparing unit 320 and surviving path memory cell and Euclidean distance memory cell 330.In detection process, analysis memory cell makes the complex convolution encoding model and trellis structure of OvTDM systems, and lists whole states of OvTDM systems, and stores.Trellis structure of the comparing unit in analysis memory cell, the path with receiving data signal minimum Eustachian distance is searched out, and surviving path memory cell and Euclidean distance memory cell are then respectively used to store the surviving path and Euclidean distance or weighted euclidean distance of comparing unit output.Surviving path memory cell and Euclidean distance memory cell need respectively to prepare one for each stable state.Surviving path memory cell length can be preferably 4K~5K.Euclidean distance memory cell is preferably only to store relative distance.

Fig. 4 shows the modulation module block diagram of the transmitting terminal of OvFDM systems.The OvFDM modulation modules of transmitting terminal may include modulation carrier spectrum generation unit 410, carrier spectrum shift unit 420, multiplication unit 430, adder unit 440 and Fourier inverse transformation unit 450.

First, the envelope frequency spectrum signal H (f) of one subcarrier of generation is designed by modulation carrier spectrum generation unit 410, carrier spectrum shift unit 420 is by the envelope frequency spectrum signal H (f) successively frequency displacement specific carriers spectrum intervals Δ B, draw the envelope frequency spectrum signal of next subcarrier, and by the envelope frequency spectrum signal frequency shift Δ B of next subcarrier, go down to obtain the spectrum waveform H (f-i × Δ B) for all subcarriers that spectrum intervals is Δ B successively.

Multiplication unit 430 is by the symbol X for the multidiameter delay to be sent_iEach subcarrier spectrum waveform H (f-i × Δ B) corresponding with generation is multiplied respectively, obtains spectrum modulation signal X of the multichannel Jing Guo corresponding subcarrier-modulated_iH(f-i×ΔB)。

The multiplexing signal spectrum formed is overlapped by adder unit 440, forms the frequency spectrum of complex modulated signal.Finally, by Fourier inverse transformation unit 450 by the polyphony of generation

The frequency spectrum of signal processed carries out discrete Fu Shi inverse transformations, ultimately forms the complex modulated signal Signal (t) of time domain_TX=ifft (S (f)).

The receiving terminal of OvFDM systems is broadly divided into signal pre-processing module 500 and signal detection module 600.Fig. 5 shows the block diagram of the signal pre-processing module of the receiving terminal of OvFDM systems.As illustrated, pretreatment module may include synchronization unit 510, channel estimating unit 520 and digitlization processing unit 530.

Synchronization unit 510 is used to dock the collection of letters number in time domain formation sign synchronization, to keep synchronous regime with system, mainly includes Timing Synchronization and carrier synchronization.Synchronously complete the rear docking of channel estimating unit 520 collection of letters number and do channel estimation, for estimating the parameter of actual transmission channel.Digitized processing unit 530 is used to the interval reception signal of each symbol time is sampled and quantified, and is allowed to be changed into digital signal sequences.

After pre-processing, the collection of letters number can be docked in signal detection module 600 to be detected.Fig. 6 shows the block diagram of the signal detection module 600 of the receiving terminal of OvFDM systems.As illustrated, signal detection module 600 may include Fourier transformation unit 610, frequency segmentation unit 620, convolutional encoding unit 630 and data detecting unit 640.Fourier transformation unit 610 is used to the time-domain signal by pretreatment being converted into frequency domain signal, i.e., the interval reception digital signal sequences of each time symbol are carried out Fourier transform to form the actual receipt signal frequency spectrum that each time symbol is interval.Frequency segmentation unit 620 is used to be segmented the interval actual receipt signal frequency spectrum of each time symbol with spectrum intervals Δ B in frequency domain, forms reality and receives signal subsection frequency spectrum.Convolutional encoding unit 630 is used for the one-to-one relationship formed between receipt signal frequency spectrum and the data symbol sequence of transmission.Data detecting unit 640 is used for the one-to-one relationship according to the formation of convolutional encoding unit, detects data symbol sequence.

It is described above the processing procedure for sending and receiving end of OvTDM systems and OvFDM systems.Although there is corresponding reception demodulation scheme to exclude overlapping brought interference of the signal in time domain or frequency domain for above-mentioned OvTDM systems and OvFDM systems, the reception greatly improved still to signal of the availability of frequency spectrum proposes requirements at the higher level.

In order to further improve the performance of multiplex system, on the basis of above-mentioned OvTDM systems and OvFDM systems, further evolution goes out OvHDM systems (Overlapped Hybrid Division Multiplexing), i.e. time-frequency Two-dimensional Overlapping multiplex system.Not only frame intersymbol is overlapped in the time domain for it, and also overlapped between frequency domain sub-carriers, realizes time domain and frequency domain is simultaneously overlapping.

As shown in figure 19, the frequency domain that can be considered as in the subcarrier after OvTDM systems is overlapping, i.e. the combination of OvTDM and OvFDM two systems for OvHDM system block diagram：Pending bit sequence carries out serioparallel exchange after gray mappings and modulation, generate multiple signals, and the processing of time domain is carried out by the OvTDM systems in foregoing, then carry out it is foregoing in subcarrier frequency domain overlap-add procedure, specific method is, to adding e per the signal handled all the way by OvTDM^{j2 π (N-1) Δ Bt}Modulation, N=1,2,3 ..., then be overlapped output.After transmission (this sentences Additive White Noise as simple formulation), first pass through N subcarriers matched filter processing (the i.e. matched filter of subcarrier 0, subcarrier 1 matched filter ... subcarrier (N-1) matched filter), to realize the inversely processing to subcarrier above Jing Guo frequency domain overlap processing, then row decoding is entered again, this sentences multi-user's maximum likelihood value-based algorithm (Multi-User Maximum Likelihood Sequence Detection, MU-MLSD) it is example, finally determine each path, obtain the output of N subcarriers, finally carry out parallel-serial conversion and obtain serial data, then it is demodulated and is operated with Gray's inverse mapping etc..

Specifically, the OvHDM systems based on Figure 19, its complex baseband signal can be expressed as：

Wherein, time domain parameter：

W (t) is the shock response of Pulse shaped filter

U (l) is l-th of symbol of system transmitting

T is the cycle of each symbol

Δ T is the interval for launching symbol, and Δ T=T/K, K are time domain overlapping multiplexing number of times

L is the total number of symbols of every frame transmitting

T_aIt is the frame length of every frame, and T_a=(L+K-1) * Δs T.

Frequency domain parameter：

N is sub-carrier number

Δ B is subcarrier spacing

D is frequency domain overlapping multiplexing number of times

Main lobe zero point bandwidth B_a=(N+D-1) * Δs B

Main lobe zero point bandwidth B=D* Δs B of each subcarrier.

And based on the OvHDM systems, the spectrum efficiency of system isWherein Q is modulation level number, and λ is the time-bandwidth product of Pulse shaped filter, i.e. λ=BT.

If L tends to infinite,

If sub-carrier number also tends to infinite, obtainThe as reachable limit spectrum efficiency of OvHDM systems.

Project training sequence is required in general communication system, it is acted on mainly after signal is received by processing, and Timing Synchronization, carrier synchronization and channel estimation can be realized simultaneously.Timing Synchronization, carrier synchronization and channel estimation are three most important links that receiving terminal is properly received.Therefore, the design of training symbol is most important, and the communication system especially for this superelevation spectrum efficiency of OvHDM systems is especially true.If either step error is larger in these three steps, the influence to whole system will be very big, and follow-up decoding process is also just nonsensical.

Current communication system is training sequence frequently with M sequence, because M sequence auto-correlation and cross correlation are poor, causes that system synchronization procedure success rate is low, and network insertion is slow.Fig. 7 shows the autocorrelation performance of M sequence, and pulse can all occur in its autocorrelation performance separated in time as we can see from the figure, and its autocorrelation performance is not fine.Therefore it is poor to the synchronization accuracy of time and frequency in signal processing, the success rate and access speed of user access network are reduced, Consumer's Experience is deteriorated.

According to an aspect of the present invention, LAS code project training sequences are utilized in OvHDM systems.It has been investigated that, it is zero everywhere beyond preferable impulse function, origin that there is LAS codes auto-correlation function, which to be in origin, and cross-correlation function is zero characteristic everywhere.This is and its favourable attribute for training sequence.In the relevant treatment of follow-up training sequence, related processing is carried out by OvHDM time-frequency two-dimensional overlapped signal.

LAS (Large Area Synchronized, large area synchronous) codes are made up of a series of 0 value pulse spacing of pulses and Length discrepancy, can be expressed as (N, K, L), wherein N represents pulse number, K represents the most short gap length between pulse, and L represents code length.Pulse is generated by complete complementary orthogonal, and it is zero everywhere beyond preferable impulse function, origin that its feature is in origin for auto-correlation function, and cross-correlation function is zero everywhere.It is applied to using this feature of LAS codes in OvHDM systems, has preferable performance improvement for the synchronous success rate and access speed of whole system.

The generation method of LAS codes is introduced briefly below.

Complete complementary orthogonal has duality relation, and generation method is the most short basic mutual-complementing code of another pair that complete orthogonal complement therewith is solved according to most short basic mutual-complementing code.With basic short code in present case +++-complete complementary orthogonal is generated, generating process is as follows：

C₀=[1 1], are corresponded to ++, S₀=[1-1], correspond to+-, according to C₀And S₀Its mutual-complementing code C is obtained respectively₁And S₁。C₁For to S₀Negate and obtain, S₁For to C₀Negating and asking to be arrived, and code is expressed as in matlab：

C₁=fliplr (S₀), S₁=-1*conj (fliplr (C0)).Wherein fliplr is that the function along vertical axis or so upset is carried out to matrix, and conj is to seek complex conjugate function.

C is tried to achieve accordingly₁=[- 1 1], S₁=[- 1-1], by C₀C₁The new mutual-complementing code of combination producing is C₀'=[1 1-1 1], S₀'=[1-1-1-1], now the length of each mutual-complementing code extends to 4 by 2.

Here the length L of mutual-complementing code can be designed_N(L_NPower side for 2), i.e. C_nAnd S_nLength be respectively L_N/2.Using the above method, the LAS codes of generation are iterated, its length is extended for L_N, iterations is log₂L_N- 2, the mutual-complementing code ultimately generated is C_n、S_n。

By this to mutual-complementing code and null sequence combination producing LAS codes, representation is：Las=[C_n L₀ S_n], wherein L₀The number of expression 0, i.e. C_nAnd S_nBetween most short gap length, the LAS code lengths ultimately generated are expressed as L=L_N+L₀。

Fig. 8 shows the autocorrelation performance of LAS codes.

According to an aspect of the present invention, LAS codes are employed and carry out project training sequence.

For the purposes of Timing Synchronization, training sequence includes at least one LAS code.Because LAS short codes still have preferable synchronous effect in the case where frequency deviation is larger, therefore, more preferably, training sequence includes at least one LAS short code, with [X_las]_SNRepresent, the length of the wherein LAS short codes is designated as SN, and its complementary code length and null sequence length is expressed as L_{It is short -N}、L_{It is short -0}, SN=L_{It is short -N}+L_{It is short -0}。

In order to further optimize the autocorrelation performance of LAS codes, a null sequence with the LAS short code equal lengths is may also include before the LAS short codes, with [0]_SNRepresent.

In specific embodiment, training sequence may include two identical LAS short codes, in the case that so a LAS short code can be used for Timing Synchronization wherein, LAS short codes pair can also be constituted with another LAS short codes, for carrier synchronization.

For the purposes of carrier synchronization, training sequence may include at least one pair of identical LAS codes.Because LAS short codes still have preferable synchronous effect in the case where frequency deviation is larger, therefore, more preferably, training sequence includes at least one pair of identical LAS short codes.

More preferably, carrier synchronization can be divided into the thick synchronous and carrier wave of two stages, i.e. carrier wave carefully synchronously.Therefore, training sequence may include at least two pairs LAS codes.More preferably, a pair of LAS codes can be slightly synchronous for carrier wave for identical LAS short codes, and another pair LAS codes can be identical LAS long codes, carefully synchronous for carrier wave.LAS long codes can use [X_las]_LNRepresent, the length of the wherein LAS long codes is designated as LN, and its complementary code length and null sequence length is expressed as L_{It is long -N}、L_{It is long -0}, LN=L_{It is long -N}+L_{It is long -0}。

In order to further optimize the cross correlation of LAS codes, a null sequence with LAS short code equal lengths is may also include before each LAS short codes, with [0]_SNRepresent.

For the purposes of channel estimation, training sequence may include at least one LAS code, such as one LAS long code, or, two LAS long codes are may also comprise, twice of channel estimation are done for the two long LAS codes, so as to improve the success rate of channel estimation.

As particular example, L can be designed_{It is long -N}=256, L_{It is long -0}=16；L_{It is short -N}=16, L_{It is short -0}=8.Certainly, LAS long codes and the length of LAS short codes here is only shown as example, may be designed as other length.

It is a kind of while the LAS code training sequences for meeting Timing Synchronization, carrier synchronization and channel estimation may be designed as preferably embodiment：[0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN,[X_las]_LN,[X_las]_LN.In this embodiment, first LAS code is short code, Timing Synchronization can be achieved, LAS short codes are in the larger synchronous effect still having had of frequency deviation.First and second LAS short code can be used for carrier wave slightly synchronous, and the benefit of short code is can to handle larger frequency deviation.Most latter two LAS code is long code, available for thin correcting frequency deviation and channel estimation.

Timing synchronization procedure

Receiver receives signal, it is necessary to first keep synchronous with communication system, including Timing Synchronization and carrier synchronization.The principle of Timing Synchronization is, by matched filtering method, will directly to receive signal and seek auto-correlation computation with local LAS codes, obtain autocorrelation peak.The position of training symbol is found according to certain method from correlation peak.The position for finding training symbol has also determined that the original position of present frame, that is, completes the time synchronized for receiving signal and system, and timing synchronization procedure terminates.

As previously described, because the auto-correlation and cross correlation of LAS codes are all relatively good, LAS codes are used for project training symbol.Thus, when calculating the related operation for receiving signal and LAS codes, peak value size distribution differs greatly, by reasonably setting threshold value, can accurately find very much the original position of LAS codes, and timing accuracy is higher.

It is specific, according to training symbol structure, to take suitable signal to receive length when finding the correlation peak of LAS codes, using sliding window method auto-correlation computation mode, signal will be received and ask related operation to find autocorrelation peak to determine the position of LAS codes with local LAS codes.For example, signal reception length here, which can ensure at least to cover, LAS codes, to guarantee to detect peak value.

So-called sliding window method auto-correlation computation, is that the docking collection of letters number takes window to handle by length of window of the length of LAS codes, this segment signal in current window and local LAS codes is made into related operation, so as to obtain an autocorrelation result.Then, window is slided backward, then docks a collection of letters number progress and take window, this segment signal in current window and local LAS codes are remake into related operation, so as to obtain a correlated results again.In this way, continuous sliding window, until all having carried out related operation to the signal received.From the whole autocorrelation results calculated, by setting threshold value, i.e., more than threshold value autocorrelation result as peak value, find the position of LAS codes.

In one example, a LAS code, such as one LAS short code, because short code still has preferable synchronous effect in the case where frequency deviation is larger are only included in training sequence.In this case, it is possible to take window to handle using the length of the LAS short codes as the length of window docking collection of letters number, this segment signal in current window and local LAS short codes are made into related operation, so as to obtain an autocorrelation result.Then, window is slided backward, then docks a collection of letters number progress and take window, this segment signal in current window and local LAS codes are remake into related operation, so as to obtain a correlated results again.In this way, continuous sliding window, until all having carried out related operation to the signal received.From the whole autocorrelation results calculated, by setting threshold value, i.e., more than threshold value autocorrelation result as peak value, find the position of LAS codes.

In the case of multipath channel, it is possible to which the amplitude for several footpaths below occur exceeds the amplitude in first footpath, it should which choosing exceedes first peak point of threshold value, and is not necessarily global maximum.Fig. 9 shows the distribution map of the autocorrelation result of Timing Synchronization.Assuming that threshold value is 100, as shown in figure 9, the autocorrelation result more than threshold value 100 there are two, but the autocorrelation results of 25 positions is chosen at as the peak value of this computing, so as to regard this as the position of the LAS codes found in 25 position.

In previous preferably training symbol format [0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN,[X_las]_LN,[X_las]_LNIn the case of, there are two LAS short codes in training sequence.Now, two peak values for exceeding threshold value can be found out by above-mentioned sliding window autocorrelation calculation method.Fig. 9 shows the distribution map of the autocorrelation result in the presence of two peak values.At this time, it may be necessary to judge which is the peak value in preceding short code, which is the peak value in rear short code.

Figure 10 shows the schematic diagram for detecting the training sequence under two peak value situations.Figure 10 illustrates two training sequences that repetitive cycling is sent.Receive two training sequences of length spans of signal, therefore, two peak values found out may one of them be due to caused by first LAS short code of next training sequence.So needing to judge which LAS short code corresponding to each peak value be.

Specifically, if two peak intervals length are 2*SN, the original position that first peak value for exceeding threshold value is first short LAS codes is so chosen, if both gap lengths are more than 2*SN, second peak value for exceeding threshold value is the original position of first short LAS codes.

If there is multipath channel, two part integrated distribution relevant peaks so occur after sliding window, relevant peaks to every part are compared with threshold value respectively, chose first peak point of threshold value, two points for exceeding threshold value will be obtained after two parts are completeer, the position of correspondence LAS codes is determined further according to method as above.

Then it is peak more smooth one by one after matched filtering in addition, if transmission signal have passed through other band limiting filters, rather than independent point, so needing to choose peak point according to actual band limiting filter.

Figure 11 shows the block diagram of the time synchronization unit of receiving terminal according to an aspect of the present invention.The time synchronization unit can be the part above in association with Fig. 2 and Fig. 5 synchronization unit discussed.

As shown in figure 11, time synchronization unit 1100 may include autocorrelation calculation unit 1110 to perform autocorrelation calculation.The autocorrelation calculation unit 1110 can carry out taking window to the signal received, to make autocorrelation calculation to the signal in window using local LAS codes, and slide the window to carry out autocorrelation calculation next time, until reaching that signal receives length.Time synchronization unit 1100 may also include peak value judging unit 1120, and the position of peak value is judged for the correlated results set according to acquisition, to find the original position of LAS codes.Peak value judging unit 1120 can choose suitable threshold value, regard the autocorrelation result more than threshold value as peak value.

Figure 12 shows the flow chart of time synchronization method according to an aspect of the present invention.As illustrated, this method may include：

Step 1201：The signal received is carried out taking window, to make autocorrelation calculation to the signal in window using local LAS codes, and the window is slided to carry out autocorrelation calculation next time, until reaching that signal receives length；And

Step 1202：The position of peak value is judged according to the correlated results set of acquisition, to find the original position of LAS codes.

As described above, in the case where there are two LAS short codes, if two peak intervals length are 2*SN, so choose the original position that first peak value for exceeding threshold value is first short LAS codes, if both gap lengths are more than 2*SN, second peak value for exceeding threshold value is the original position of first short LAS codes.

Carrier synchronization process

Receive after signal, it is necessary to first keep synchronous with communication system, including Timing Synchronization and carrier synchronization, the synchronization on signal and system first retention time is received, the original position of LAS codes is obtained by Timing Synchronization, then enter the synchronization of line frequency.

For carrier synchronization, receiving the training sequence message part of signal includes at least one pair of identical LAS codes.Computing cross-correlation is carried out to the LAS codes repeated, frequency deviation f is obtained.

Assuming that the carrier deviation between receiver and emitter be Δ f, the AD sampling interval be T, then receiving terminal ignore noise signal influence when, the signal received is expressed as：

y_n=x_ne^{j2 πΔ fnT}

The coefficient correlation of former and later two LAS codes is：

Wherein L represents the interval between LAS codes.

From above formula, carrier wave frequency deviation is：

More preferably, training sequence message part may include two pairs of LAS codes, wherein, a pair of identical LAS codes are LAS short codes, it is possible thereby to which it is slightly synchronous first to carry out carrier wave；Include a pair of identical LAS long codes again in addition, it is possible thereby to which it is carefully synchronous to carry out carrier wave.

Due to having been completed Timing Synchronization, the training symbol index that can be returned according to Timing Synchronization extracts the corresponding short LAS codes of two parts, carrier wave is carried out to short LAS codes slightly synchronous, short code can handle larger frequency deviation, it is Δ f that the frequency deviation value estimated is calculated according to above-mentioned formula₁.Then the long LAS codes of two parts are extracted again, the thin correcting frequency deviation of carrier wave is carried out to long LAS codes, and the frequency deviation value estimated is Δ f₂, with reference to thick synchronous frequency deviation, then the frequency deviation of final output is Δ f=Δs f₁+Δf₂。

With previous preferably training symbol format [0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN,[X_las]_LN,[X_las]_LNExemplified by.LN=272, SN=24 are made, training symbol total length is 640.Two short LAS are respectively (25:48) with (73:96) two positions, long LAS code divisions are not (97:368) with (369：640) two positions.

Ideally, the original position that Timing Synchronization calculates obtained LAS codes is the original position of first short LAS codes, as 25.It is corresponding from signal is received to extract corresponding code according to this index and the code length LN and SN of long short code.

Carrier wave is slightly synchronous

The short LAS codes of two parts are extracted from signal is received, according to formulaConjugate multiplication is asked to it, coefficient R is obtained.Further according to formulaObtain corresponding thick frequency deviation Δ f₁, wherein L represents the interval between two short LAS codes, the L=2*SN=48 it can be seen from training symbol structure.

Thick frequency deviation according to calculating passes through formulaThe docking collection of letters number carries out a frequency offset correction, obtains the signal after first time frequency offset correction.

The thin frequency offset correction of carrier wave

The docking collection of letters number has carried out thick frequency offset correction in the thick synchronization of carrier wave, obtains receiving signal y_n'.Thin frequency deviation process is from y_n' in extract the long LAS codes of two parts, according to formulaConjugate multiplication is asked to it, coefficient R is obtained.Further according to formulaObtain corresponding thin frequency deviation Δ f₂, L represents the interval between two long LAS codes, the L=LN=272 it can be seen from training symbol structure.

With reference to thick synchronous frequency deviation, then the frequency deviation of final output is Δ f=Δs f₁+Δf₂.And according to formula y_n"=y_n'e^{j2 π (- Δ f)nT}Obtain the signal after the thin correcting frequency deviation of the docking collection of letters number.

By the signal y after frequency offset correction twice_n" as input signal to channel estimation process, carrier synchronization process terminates.

Figure 13 shows the block diagram of carrier synchronization unit 1300.The carrier synchronization unit 1300 can be the part above in association with Fig. 2 and Fig. 5 synchronization unit discussed.

As illustrated, carrier synchronization unit 1300 may include cross-correlation calculation unit 1310 and frequency correction unit 1320.Cross-correlation calculation unit 1310 can perform cross-correlation calculation to obtain the frequency deviation of carrier wave between receiving terminal and transmitting terminal to a pair of LAS codes.Frequency correction unit 1320 can be according to the frequency deviation of the carrier wave, and docking, which is collected mail, number performs a frequency offset correction.

In one embodiment, the cross-correlation calculation of a pair of LAS short codes can be first carried out in cross-correlation calculation unit 1310, to obtain the thick frequency deviation of carrier wave between receiving terminal and transmitting terminal.Frequency correction unit 1320 can be first according to the thick frequency deviation, and the docking collection of letters number performs a first frequency offset correction.Cross-correlation calculation unit 1310 performs cross-correlation calculation to a pair of the LAS long codes extracted from the reception signal by first frequency offset correction again, to obtain the thin frequency deviation of carrier wave between receiving terminal and transmitting terminal.Frequency correction unit 1320 can perform secondary frequency offset correction, to obtain the signal after final frequency offset correction further according to the thin frequency deviation and the thick frequency deviation to the reception signal through first frequency offset correction.

Figure 14 shows the flow chart of the carrier synchronization method according to an embodiment.As illustrated, carrier synchronization method may include following steps：

Step 1401：To performing cross-correlation from two LAS codes for receiving signal extraction, to obtain the frequency deviation of carrier wave between receiving terminal and transmitting terminal；And

Step 1402：A frequency offset correction is performed based on the frequency deviation docking collection of letters number.

Figure 15 shows the flow chart of the carrier synchronization method according to another embodiment.As illustrated, carrier synchronization method may include following steps：

Step 1501：To performing cross-correlation from two LAS short codes for receiving signal extraction, to obtain the thick frequency deviation of carrier wave between receiving terminal and transmitting terminal；

Step 1502：According to the thick frequency deviation, the docking collection of letters number performs a first frequency offset correction；

Step 1503：Cross-correlation calculation is performed to a pair of the LAS long codes extracted from the reception signal through first frequency offset correction, to obtain the thin frequency deviation of carrier wave between receiving terminal and transmitting terminal；And

Step 1504：According to the thin frequency deviation and the thick frequency deviation, secondary frequency offset correction is performed to the reception signal through first frequency offset correction.

Although the above method is illustrated and is described as a series of actions to simplify explanation, it should be understood that and understand, the order that these methods are not acted is limited, because according to one or more embodiments, some actions can occur in different order and/or with from it is depicted and described herein or not shown herein and describe but it will be appreciated by those skilled in the art that other actions concomitantly occur.

Channel estimation process

Channel estimation is used for the transmission characteristic for estimating channel, i.e., channel is to the influence of the signal transmitted.By using training symbol known to transmitting terminal and receiving terminal both sides, receiving terminal can perform channel estimation according to the known training symbol and the training symbol received.For example, receiving terminal can perform correlation to known training symbol and the training symbol received, so that it is determined that the transmission characteristic of channel.After channel estimation is carried out, receiving terminal can demodulate the unknown data signal received using identified channel estimation, to determine the actual data signal of transmitting terminal transmission.

Receive signal and pass through Timing Synchronization, and system hold time synchronization.Then again with receive signal and do carrier synchronization, carrier synchronization includes thick synchronous and thin synchronous, and by the synchronous carrier wave frequency deviation Δ f for obtaining receiver and transmitter, the signal of reception is corrected by carrier wave frequency deviation, revised reception signal y is obtained_fix, to y_fixDo channel estimation.

The present invention is using LAS codes as training sequence, such as the long LAS codes L-LAS in training symbol format is available for channel estimation.

Channel estimation is represented by：

Wherein y_nRepresent to pass through the revised reception signal of carrier synchronization, i.e. y_fix.N represents LAS code lengths.x_nRepresent local LAS codes, i.e. x_nIt is expressed as most one of latter two long LAS code in training symbol.R₀The quadratic sum of LAS codes is represented, P represents multipath channel number.

Reception signal y of the channel estimator from training symbol_fixThe impulse response h (t) of middle estimation channel, then constructs an inverse channel system according to the h (t) that estimates, and the data-signal received passes through after the inverse channel system estimation for being reduced into the signal that channel is fed to transmitting terminal.

It is general to receive signal y_nIt can be expressed ase_nRepresent noise.Equation below is obtained after being substituted into above formula expansion：

The auto-correlation of training sequence is represented, is zero by rationally designing auto-correlation coefficient, estimation channel height is close to real channel, so as to drastically increase the precision of channel estimation.According to the present invention, because the probability that LAS codes auto-correlation occurs 0 is high, therefore the success rate of channel estimation is substantially increased when carrying out channel estimation.

This area typically carries out channel estimation using M sequence.As shown in Figure 7, pulse can all occur to the autocorrelation performance of M sequence in its autocorrelation performance separated in time as we can see from the figure, and its autocorrelation performance is not fine, respective channels estimation formulas

InValue is not very big for 0 probability, therefore the channel model and ideal communication channel model bias that estimate are larger, influences very big for follow-up decoding processing, improves the bit error rate of system.

Contrast LAS code sequences, there is auto-correlation function to be preferable impulse function in origin for it, it is zero everywhere beyond origin, and cross-correlation function the characteristics of be zero everywhere, therefore when doing channel estimation, channel model and ideal model deviation very little that actual estimated goes out, reduce the bit error rate of system, good improvement have been obtained to systematic function.

According to the present invention, because long LAS codes have two in training symbol, therefore channel estimation process can be realized using the long LAS codes of any of which, or can also do twice of channel estimation for the two long LAS codes, so as to improve the success rate of channel estimation.

A channel or multipath channel may be present in a communication environment, receiver can determine whether there is multipath channel according to environment.In the case of no multipath channel, i.e. p=0 can directly calculate channel estimation h according to above formula.And in the case where there is multipath channel, the channel estimation value h of every multiple paths can be calculated respectively according to above formula_p, wherein for every multiple paths by local LAS codes x_nEnter line displacement, the deviation of each paths can be 1.

For example, actual multipath channel can be such as 6.Local LAS codes are arranged in 6 row according to multipath number first, the deviation in each row path is 1, and arrangement mode is as shown in Figure 16.

According to training symbol format [0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN,[X_las]_LN,[X_las]_LN, from revise signal y_fixIn find corresponding LAS code positions, and extract as y_fix-las, common two parts.

By the y extracted_fix-lasPass through formula with the local LAS codes of 6 multipath channels after rearranging respectively

After processing, the channel estimation value h of every multiple paths is obtained_p.Because shared two parts LAS codes can carry out channel estimation, channel estimation value h can be all obtained per part after treatment_p, two parts are averaged, the channel estimation value h of every last multiple paths is can obtain_p。

Then, can the channel estimation value h based on every multiple paths_pTo demodulate the data-signal received, so that the transmission end signal of every multiple paths must be recovered.

Project training sequence frequency range

Design symbols structure includes training sequence TSC (traning sequence code) and data (data) in the system.The design of training symbol is most important, it have impact on the timing, synchronization, three most important links of channel estimation of whole system, if either step error is larger in these three steps, the influence to whole system will be very big, and follow-up decoding process is also just nonsensical.

The design process of training sequence frequency range is complex, its corresponding power spectral density is larger when frequency range is shorter, the reception and transmission of data can be influenceed when there is multiple carrier waves in system, corresponding power spectral density is too small when frequency range is excessive, the sensitivity requirement of transmitter and receiver to system is high.

In existing communication system, typically using training sequence and the frequency range identical method of data, its corresponding power spectral density is identical, and due in General System frequency range it is all shorter, therefore the time is sent corresponding to time domain longer, influence signal is synchronous, channel estimation process time course, and the follow-up decoding process stand-by period is also elongated, reduces the transmission rate of system.Further, since the training sequence transmission time is longer, therefore when being sampled to signal, its sample rate is relatively low, and temporal resolution is not fine enough, influences the deviation of channel estimation.

The invention enables training sequence frequency range much larger than data bandwidth (for example, 5 times, 10 times, 15 times or more), it is less than the power spectral density of data so as to the power spectral density of training sequence, its training sequence, the frequency range of data and power spectral density graph of a relation are as shown in Figure 17.Because the transmit power of training sequence and data need to be consistent, as can be seen from Figure, after the frequency range of training sequence broadens, its corresponding power spectral density can consequently also be greatly lowered, and be very low for data power spectral density.

The system can use all available spreading codes, including m-sequence, Golomb codes, CAN (Cyclic Algorithm New) and LAS codes etc..We introduce the processing procedure of Timing Synchronization, carrier synchronization and channel estimation by taking the LAS codes with complete complementary orthogonal property as an example in the system.Therefore, it is previously described to be timed synchronization, carrier synchronization, all method and devices of channel estimation as midamble code by the use of LAS codes and be also applied for all suitable spreading codes and be timed synchronization, carrier wave and training as midamble code estimating.Therefore, it is merely possible to above by the algorithm of the Timing Synchronization exemplified, carrier synchronization and channel estimation of LAS codes shown in example, the above of the invention is applied to all suitable midamble codes.

The characteristics of LAS codes be auto-correlation function be in origin be zero everywhere beyond preferable impulse function, origin, and cross-correlation function is zero everywhere, and the autocorrelation performance of LAS codes is as shown in Figure 8.Therefore also will not mutually it be interfered when training sequence is overlapping.So design can improve the availability of frequency spectrum and transmission rate of system.

By formulaUnderstand, when frequency domain frequency range is bigger, its correspondence is smaller in the time of time domain, i.e., can just complete training sequence in the short period of time sends and receives process.Receive process in signal, for the data of same length, when 330 receiving between shorten, the sample rate of signal can be improved so that temporal resolution is finer.The accuracy of temporal resolution is improved in channel estimation process so that channel estimation results are more accurate.

On the one hand, because the power spectral density of training sequence is extremely low, influence is hardly produced on data-signal, therefore training sequence and data can be superimposed in the same time and send.In other words, training sequence and data are at least partially overlappingly sent in frequency and/or on the time.When there is two carrier signals to send data simultaneously, its structural map as shown in Figure 18, it can be seen that having protection band in the middle of the real data that two carrier waves are carried, overlapping also will not will not be interfered mutually；And the frequency range and real data of training sequence have overlapping, because training sequence power spectral density is very low, therefore real data will not be interfered；Further, different training sequences can be distinguish between with different spreading codes, do not result in and obscure.Training sequence does not monopolize specific frequency and time resource, improves the availability of frequency spectrum and transmission rate of system.

In one embodiment, the LAS codes with complete complementary orthogonal property can be used in the system for training sequence, its feature is that auto-correlation function is preferable impulse function in origin, it is zero everywhere beyond origin, and cross-correlation function is zero everywhere, the auto-correlation and cross correlation of LAS codes are as shown in Figure 5.Therefore also will not mutually it be interfered when training sequence is overlapping.So design can improve the availability of frequency spectrum and transmission rate of system.

Our forms of project training sequence are in present case：[0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN,[X_las]_LN,[X_las]_LN。

It will be understood by those skilled in the art that any technology and skill in various different technologies and skill can be used to represent for information, signal and data.For example, data, instruction, order, information, signal, position (bit), symbol and chip that above description is quoted from the whole text can be represented by voltage, electric current, electromagnetic wave, magnetic field or magnetic particle, light field or optical particle or its any combinations.

Those skilled in the art will further appreciate that various illustrative logic plates, module, circuit and the algorithm steps described with reference to the embodiments described herein can be realized as electronic hardware, computer software or combination of the two.Clearly to explain this interchangeability of hardware and software, various illustrative components, frame, module, circuit and step are to make vague generalization description in its functional form above.Such feature is implemented as hardware or software depends on concrete application and puts on the design constraint of total system.Technical staff can realize described feature for every kind of application-specific with different modes, but such realize that decision-making should not be interpreted to cause departing from the scope of the present invention.

With reference to the various illustrative logic modules and circuit that presently disclosed embodiment is described can with general processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA) or other PLDs, discrete door or transistor logic, discrete nextport hardware component NextPort or its be designed to carry out any combinations of function described herein and realize or perform.General processor can be microprocessor, but in alternative, the processor can be any conventional processor, controller, microcontroller or state machine.Processor is also implemented as the combination of computing device, one or more microprocessors or any other such configuration that such as DSP cooperates with the combination of microprocessor, multi-microprocessor, with DSP core.

It can be embodied directly in hardware, in and be embodied in the software module of computing device or in combination of the two with reference to the step of the method or algorithm that embodiment disclosed herein is described.Software module can reside in the storage medium of RAM memory, flash memory, ROM memory, eprom memory, eeprom memory, register, hard disk, removable disk, CD-ROM or any other form known in the art.Exemplary storage medium is coupled to processor to enable the processor to read and write information from/to the storage medium.In alternative, storage medium can be integrated into processor.Processor and storage medium can reside in ASIC.ASIC can reside in user terminal.In alternative, processor and storage medium can be resident in the user terminal as discrete assembly.

In one or more exemplary embodiments, described function can be realized in hardware, software, firmware or its any combinations.If being embodied as computer program product in software, each function can be stored on a computer-readable medium as the instruction of one or more bars or code or transmitted by it.Computer-readable medium includes both computer-readable storage medium and communication media, and it includes any medium for facilitating computer program to shift from one place to another.Storage medium can be any usable medium that can be accessed by a computer.It is non-limiting as example, such computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage apparatus can be used to carry or store instruction or data structure form desirable program code and any other medium that can be accessed by a computer.Any connection is also properly termed a computer-readable medium.For example, if software is to be transmitted using the wireless technology of coaxial cable, fiber optic cables, twisted-pair feeder, digital subscriber line (DSL) or such as infrared, radio and microwave etc from web site, server or other remote sources, the wireless technology of the coaxial cable, fiber optic cables, twisted-pair feeder, DSL or such as infrared, radio and microwave etc is just included among the definition of medium.Disk (disk) and dish (disc) as used herein include compact disc (CD), laser disc, laser disc, digital versatile disc (DVD), floppy disk and blu-ray disc, which disk (disk) often reproduce data in the way of magnetic, and dish (disc) laser reproduce data optically.Combinations of the above should be also included within the scope of computer readable media.

It is for so that any person skilled in the art all can make or use the disclosure to provide of this disclosure be previously described.Various modifications of this disclosure all will be apparent for a person skilled in the art, and the generic principles defined herein can be applied to spirit or scope of other variants without departing from the disclosure.Thus, the disclosure is not intended to be limited to example described herein and design, but the widest scope consistent with novel features with principle disclosed herein should be awarded.

Claims (22)

1. a kind of time synchronization method, including：

Signal and local midamble code execution auto-correlation computation will be received using sliding window method, it is multiple to obtain Autocorrelation result, wherein the reception signal is the time-frequency two-dimensional overlapped signal from transmitting terminal and wherein Including training sequence and data based on midamble code, wherein training sequence frequency range be more than data bandwidth and The power spectral density of training sequence is less than the power spectral density of data；And

Autocorrelation peak is determined from the multiple autocorrelation result, with the position of the autocorrelation peak As the original position of the midamble code, the original position of the midamble code is used to determine that described receive is believed Number timing.

2. time synchronization method as claimed in claim 1, it is characterised in that the midamble code bag Include m-sequence, Golomb codes, CAN codes or LAS codes.

3. time synchronization method as claimed in claim 1, it is characterised in that the training sequence Frequency range is more than 5 times, 10 times, 15 times or more of data bandwidth.

4. time synchronization method as claimed in claim 1, it is characterised in that the use sliding window Method, which will receive signal and local midamble code execution auto-correlation computation, to be included：

Length using the length of the midamble code as window takes window to the reception signal, by current window The interior signal section that receives performs auto-correlation computation with local midamble code, to obtain an autocorrelation result；

The window is slided backward to take window again to the reception signal, again by current window The signal section that receives perform auto-correlation computation with local midamble code, to obtain another autocorrelation result； And

Repeat sliding window and the signal section that receives in window is performed into auto-correlation with local LAS The step of computing, until the auto-correlation processing that whole length receives signal is completed, it is described many to obtain Individual autocorrelation result.

5. time synchronization method as claimed in claim 1, it is characterised in that the training sequence Including a midamble code, wherein determining that autocorrelation peak includes from the multiple autocorrelation result：

Only one autocorrelation peak is determined from the multiple autocorrelation result.

6. time synchronization method as claimed in claim 5, it is characterised in that from it is the multiple from Determine that only one autocorrelation peak includes in correlated results：

It regard more than the first of predetermined threshold autocorrelation result as the only one autocorrelation peak.

7. time synchronization method as claimed in claim 5, it is characterised in that one training Code is LAS short codes.

8. time synchronization method as claimed in claim 1, it is characterised in that the training sequence Including two midamble codes of identical, wherein determining autocorrelation peak bag from the multiple autocorrelation result Include：

Two autocorrelation peaks are determined from the multiple autocorrelation result；And

Determined from described two autocorrelation peaks with the associated peak value of preceding midamble code, with it is described The position for the peak value being associated in preceding midamble code as the original position in preceding midamble code, it is described The original position of preceding midamble code is used for the timing for determining the reception signal.

9. time synchronization method as claimed in claim 8, it is characterised in that described two training Code is LAS short codes.

10. time synchronization method as claimed in claim 9, it is characterised in that the training sequence Including：[0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN, wherein [0]_SNFor 0 sequence that length is SN, [X_las]_SN The LAS short codes for being SN for length, wherein from described two autocorrelation peaks determine with The peak value of preceding LAS code-phases association includes：

If the gap length between described two autocorrelation peaks is 2*SN, by described two from phase First autocorrelation peak closed in peak value is defined as the peak value associated with preceding LAS code-phases,

If gap length between described two autocorrelation peaks is more than 2*SN, will it is described two oneself Second autocorrelation peak in correlation peak is defined as the peak value associated with preceding LAS code-phases.

11. time synchronization method as claimed in claim 8, it is characterised in that from it is the multiple from Determine that two autocorrelation peaks include in correlated results：

Two of integrated distribution more than predetermined threshold are determined from the multiple autocorrelation result from phase Close result subset；And

It regard the autocorrelation result that first in each autocorrelation result subset exceedes the threshold value as institute Autocorrelation peak is stated, so as to obtain described two autocorrelation peaks.

12. a kind of timing synchronization device, including：

Autocorrelation calculation unit, is performed certainly for that will receive signal using sliding window method with local midamble code Related operation, to obtain multiple autocorrelation results, wherein when the reception signal is from transmitting terminal Frequency Two-dimensional Overlapping signal and including training sequence and data based on midamble code, wherein training sequence Row frequency range is more than power spectral density of the power spectral density less than data of data bandwidth and training sequence；With And

Peak value judging unit, for determining autocorrelation peak from the multiple autocorrelation result, with institute The position of autocorrelation peak is stated as the original position of the midamble code, the original position of the midamble code Timing for determining the reception signal.

13. timing synchronization device as claimed in claim 1, it is characterised in that the midamble code bag Include m-sequence, Golomb codes, CAN codes or LAS codes.

14. timing synchronization device as claimed in claim 1, it is characterised in that the training sequence Frequency range is more than 5 times, 10 times, 15 times or more of data bandwidth.

15. timing synchronization device as claimed in claim 12, it is characterised in that the auto-correlation Computing unit is further used for：

Length using the length of the midamble code as window takes window to the reception signal, by current window The interior signal section that receives performs auto-correlation computation with local midamble code, to obtain an autocorrelation result；

The window is slided backward to take window again to the reception signal, again by current window The signal section that receives perform auto-correlation computation with local midamble code, to obtain another autocorrelation result； And

Repeat sliding window and the signal section that receives in window is performed into auto-correlation with local LAS The step of computing, until the auto-correlation processing that whole length receives signal is completed, it is described many to obtain Individual autocorrelation result.

16. timing synchronization device as claimed in claim 12, it is characterised in that the training sequence Row include a midamble code, and the peak value judging unit is further used for from the multiple autocorrelation result Middle determination only one autocorrelation peak.

17. timing synchronization device as claimed in claim 16, it is characterised in that the peak value is sentenced Disconnected unit is further used for regarding more than the first of predetermined threshold autocorrelation result as described unique one Individual autocorrelation peak.

18. timing synchronization device as claimed in claim 16, it is characterised in that one instruction It is LAS short codes to practice code.

19. timing synchronization device as claimed in claim 12, it is characterised in that the training sequence Row include two midamble codes of identical, wherein the peak value judging unit is further used for：

Two autocorrelation peaks are determined from the multiple autocorrelation result；And

Determined from described two autocorrelation peaks with the associated peak value of preceding midamble code, with it is described The position for the peak value being associated in preceding midamble code as the original position in preceding midamble code, it is described The original position of preceding midamble code is used for the timing for determining the reception signal.

20. timing synchronization device as claimed in claim 19, it is characterised in that described two instructions It is LAS short codes to practice code.

21. timing synchronization device as claimed in claim 20, it is characterised in that the training sequence Row include：[0]_SN,[X_las]_SN,[0]_SN,[X_las]_SN, wherein [0]_SNFor 0 sequence that length is SN, [X_las]_SN The LAS short codes for being SN for length, the peak value judging unit is further used for：

If the gap length between described two autocorrelation peaks is 2*SN, by described two from phase First autocorrelation peak closed in peak value is defined as the peak value associated with preceding LAS code-phases,

If gap length between described two autocorrelation peaks is more than 2*SN, will it is described two oneself Second autocorrelation peak in correlation peak is defined as the peak value associated with preceding LAS code-phases.

22. timing synchronization device as claimed in claim 19, it is characterised in that the peak value is sentenced Disconnected unit is further used for：

Two of integrated distribution more than predetermined threshold are determined from the multiple autocorrelation result from phase Close result subset；And

It regard the autocorrelation result that first in each autocorrelation result subset exceedes the threshold value as institute Autocorrelation peak is stated, so as to obtain described two autocorrelation peaks.