CN101536385A - Preamble detection and synchronization in OFDMA wireless communication systems - Google Patents

Abstract

An embodiment of the invention is a technique for preamble detection and synchronization. A symbol correlation of a sequence of symbols is computed in a correlation window using one of a time-domain correlation and a frequency-domain correlation. The sequence of symbols is received in an orthogonal frequency division multiple access (OFDMA) wireless communication. A symbol is verified from the symbol correlation. The symbol is one of a preamble symbol and a data symbol.

Description

Detection of preamble in the OFDMA wireless communication system and synchronous

Related application

That the application requires is that submit on November 7th, 2006, name is called the provisional application No.60/857 of " Preamble detection andsynchronization in OFDMA wireless communication systems ", 528 priority.

Technical field

Embodiments of the invention relate to OFDM (OFDMA) wireless communication system, and specifically, embodiments of the invention relate to the detection of preamble and synchronously in the OFDMA system.

Background technology

In the middle of various communication transmission technologies, OFDM (OFDM), because of its to the property resisted of intersymbol interference and its spectral efficient, be considered to the selection of tool prospect.

OFDMA is a multi-user OFDM, and it can realize on identical channel that multichannel inserts.In OFDMA time division duplex (TDD) system, frame structure is that the transmission according to base station (BS) and mobile subscriber station (MSS) forms.The base station sends information via down link (DL) wireless signal to its service mobile subscriber station.Mobile radio station (MS) or subscriber station (SS) send information via up link (UL) wireless signal to its serving BS.OFDMA is allocation of subcarriers between the user, and thus, whole active users can send on single channel and receive simultaneously.

According to current defined WiMAX standard-IEEE 802.16E, first symbol of downlink transmission is leading.Leadingly be used for carrying out initial synchronisation by mobile radio station.In order to send and received frame, base station and mobile radio station must obtain each other synchronously.For obtain each other synchronously, MS need detect the leading starting position of sending from BS.

There are many defectives in the prior art that is used for preamble synchronization.Relevant based between the Cyclic Prefix of OFDM symbol and the decline of basic detection of preamble scheme.Symbol in the Cyclic Prefix is a copy and come from the decline of OFDM symbol.By calculating received sequence and postponing being correlated with between the version, can estimate the position of Cyclic Prefix.Although leading signal power is higher than the power (this means leading CP relevant have bigger relevant output) of general OFDM data symbol comparatively speaking, yet, general OFDM data and leading very difficult distinguished.

A kind of possible solution for this problem is: the CP that checking is detected is from leading symbol, still from data symbol.There is a kind of verification technique to be applicable to the WiMAX standard.In the WiMAX standard, there is 114 kinds of pseudo noises (PN) sequence to be used for leading from different base station and different sectors.Carry out checking by the cross-correlation of calculating between received sequence and all available PN sequence.In the process of carrying out cross-correlation, the computing cost that this Technology Need is very big.In addition, can't eliminate integer frequency offset based on the frequency offset estimating of Cyclic Prefix, this makes modulation sequence be displaced to another subcarrier from a subcarrier.This will further significantly increase the amount of calculation.

Another kind of technology is to carry out detection according to the conjugation symmetry in time domain.This technology all needs a large amount of complex multiplication operations to the checking of each position.

Also has a kind of technology based on leading repeat property.In the WiMAX standard, targeting sequencing evenly is modulated on each the 3rd subcarrier.From the signal of a piece and from arbitrary signal correction in other two pieces.Although this scheme is efficiently in single-cell environment, it is ineffective in many cell environments, because be modulated on the different sub-carrier set from the leading of different base station.

Summary of the invention

Embodiments of the invention are to be used for detection of preamble and synchronous technology.In correlation window, use time domain relevant and come the symbol of compute sign sequence to be correlated with one of during frequency domain is relevant.Symbol sebolic addressing receives in OFDM (OFDMA) radio communication.Be correlated with according to symbol and verify symbol.Described symbol is one of in leading symbol and the data symbol.

Description of drawings

By with reference to following description and accompanying drawing, can better understand embodiments of the invention in order to the explanation embodiments of the invention.In the accompanying drawings:

Fig. 1 shows the diagram of system according to an embodiment of the invention.

Fig. 2 shows the diagram of preamble detector/synchronizer according to an embodiment of the invention.

Fig. 3 shows the relevant diagram relevant with frequency domain of time domain according to an embodiment of the invention.

Fig. 4 shows the diagram of frequency-domain correlator according to an embodiment of the invention.

Fig. 5 shows the diagram of validator according to an embodiment of the invention.

Fig. 6 shows the flow chart of processing procedure according to an embodiment of the invention, and this processing procedure is used to detect leading and synchronous.

Fig. 7 A shows the flow chart of processing procedure according to an embodiment of the invention, and this processing procedure is used to use time domain to be correlated with compute sign relevant.

Fig. 7 B shows the flow chart of processing procedure according to an embodiment of the invention, and this processing procedure is used to use frequency domain to be correlated with compute sign relevant.

Fig. 8 shows the flow chart of processing procedure according to an embodiment of the invention, and this processing procedure is used to verify symbol.

Fig. 9 shows the diagram of processing subsystem according to an embodiment of the invention, and this subsystem is used to carry out detection of preamble and synchronous.

Embodiment

Embodiments of the invention are to be used for detection of preamble and synchronous technology.In correlation window, use time domain relevant and come the symbol of compute sign sequence to be correlated with one of during frequency domain is relevant.Symbol sebolic addressing receives in OFDM (OFDMA) radio communication.Be correlated with according to symbol and verify symbol.Described symbol is one of in leading symbol and the data symbol.

In the following description, a large amount of details have been provided.Yet, should be appreciated that also and can realize embodiments of the invention without these details.In other example, not shown known circuits, structure and technology are to avoid confusion to the understanding of this description.

Can use flow chart, process diagram, structure chart or block diagram that one embodiment of the present of invention are described as processing procedure.Be described as a sequential processes process although use flow chart much to operate, a lot of operations are to walk abreast or to carry out simultaneously.And, can adjust the order of these operations.When these EOs, processing procedure has also just terminated.Processing procedure can be corresponding to method, program, process, manufacturing or manufacture method or the like.

Embodiments of the invention comprise the time synchronized preparation method that is used in the OFDMA wireless communication system.This method comprises two stages: first stage is used for detecting according to the Cyclic Prefix coarse boundaries of carrying out the OFDM symbol of being correlated with; Second stage is used to verify that current sign is OFDM leading symbol or OFDM data symbol.Second stage also is used to estimate fine symbol boundary.Proof procedure is based on the leading conjugate symmetry of binary phase shift keying (BPSK) Modulation OFDM.For this process, there are two kinds of alternative methods: time domain processing scheme and frequency processing scheme.In order to judge whether current sign is BPSK Modulation OFDM symbol, the maximum of relevant output and summation and their corresponding predetermined threshold value of some very big relevant outputs are compared.In addition, the input and the character boundary that can be applicable to BPSK Modulation OFDM symbol estimated second stage.

Fig. 1 shows the diagram of system 100 according to an embodiment of the invention.System 100 comprises base station (BS) 110 and N mobile radio station (MS) 140 ₁To 140 _NIt should be noted that the parts that system 100 comprises can also can be less than above-mentioned parts more than above-mentioned parts.

BS 110 is mounted in the station of fixed position or shift position, is used under wireless communications mode via radio frequency (RF) transmission and N MS 140 ₁To 140 _NCommunicate.Radio communication is followed micro-wave access to global intercommunication (WiMAX) standard.Described position can be positioned at densely populated area, also can be positioned at underpopulated area, or is used for vehicular applications.BS 110 comprises BS processing unit 120 and BS emittor/receiver 130.

BS processing unit 120 comprises the necessary parts that are used for the BS operation.BS processing unit 120 comprises: oscillator, and the various parts (such as analog to digital converter (ADC), digital to analog converter (DAC) and other logical circuit) that are used for to described unit provide clock source or signal; One or more processors (such as digital signal processor (DSP)) are used to carry out various functions or working procedure; Automatic gain control (AGC); Automatic frequency control (AFC) and channel coding/decoding module or circuit or the like.BS processing unit 120 comprises: BS symbol maker 125 is used for generation and will be transferred to N MS 140 ₁To 140 _NSymbol sebolic addressing.

BS emittor/receiver 130 comprises: transmitter unit is used to send the RF signal; Receiving element is used to receive the RF signal.BS emittor/receiver 130 can comprise the high power antenna.According to type or the landform and the desired overlay area of antenna, antenna can be installed on the roof, on the tower or the mountain top.

N MS 140 ₁To 140 _NCan comprise any MS equipment, such as mobile phone, cell phone, PDA(Personal Digital Assistant), notebook, laptop computer or can in cordless communication network, carry out any equipment of MS function.N MS 140 ₁To 140 _NIn each can subscribe to the mobile communication service that BS 110 is provided.N MS 140 ₁To 140 _NIn each all comprise: radio frequency (RF) receiver is used for receiving the wireless signal that carries symbol sebolic addressing from BS 110 in OFDM (OFDMA) radio communication; Preamble detector and synchronizer 145 _i(i=1 ..., N), be used to detect leading symbol and synchronization frame; Cyclic Prefix (CP) arrester is used to eliminate CP; Fast Fourier transform (FFT) processor is used to calculate FFT; Channel equalizer; Channel estimator; Decoder; Deinterleaver; Be used to carry out other circuit or the module of receiving function.N MS 140 ₁To 140 _NIn each also comprise: channel encoder and interleaver, binary phase shift keying (BPSK) mapper, contrary FFT (IFFT) processor, Cyclic Prefix and window treatments unit, RF transmitter and be used to carry out other circuit or the module of emission function.

BS 110 an and N MS 140 ₁To 140 _NAccording to predetermined communication protocol or standard, intercommunication each other.In one embodiment, communication standard is institute of electrical and electronic engineers (IEEE) 802.16e standard or ETSI (ETSI) high-performance wireless MAN (HiperMAN) 1.3.2 standard.MS preamble detector/synchronizer 145 _iProvide detection of preamble efficiently to frame synchronization.In typical WiMAX system, BS 110 an and N MS 140 ₁To 140 _NComprise medium access control (MAC) layer and physical layer (PHY) feature.The WiMAX system uses OFDM (OFDMA) scheme at multi-path environment.

Fig. 2 shows preamble detector/synchronizer 145 according to an embodiment of the invention _iDiagram.For simplicity's sake, omit subscript " I ".Preamble detector/synchronizer 145 comprises correlator 210 and validator 240.The parts that preamble detector/synchronizer 145 comprises can also can be less than above-mentioned parts more than above-mentioned parts.In addition, preamble detector/synchronizer 145 can realize by hardware, firmware or software or their combination in any.

Correlator 210 one of uses in time domain correlator 220, the frequency-domain correlator 230 symbol of compute sign sequence relevant in correlation window L.This symbol sebolic addressing receives in the OFDMA radio communication.This symbol sebolic addressing can be represented any symbol that transmitter (for example, BS 110) is generated.Described symbol can be formed on leading in employed Cyclic Prefix (CP), also can represent data symbol, wherein, described data symbol is the part of communication information.

Time domain correlator 220 uses conjugate symmetric sequence relevant at the time domain compute sign in checking window K.The checking window is more young than associated window, and also, the length of checking window is less than the length L of correlation window.Checking window K can pass through minimum index-K _w, largest index K _wRepresent, wherein, length of window K=2K _w+ 1.Give an example, if K _w=3 ,-3 ,-2 ,-1,0,1,2,3 verify that so window K has following index:.

Frequency-domain correlator 230 is converted to circular convolution by being correlated with, and is relevant at the frequency-domain calculations symbol.Can be in time domain computation cycles convolution, also can be at the frequency-domain calculations circular convolution.Because fast Fourier transform (FFT) can be used for Fourier transform (FT) is calculated fast, so frequency domain convolution is more efficient.In addition, in the receiver of MS 140, FFT calculates normally available.Thus, no longer needing other hardware or software to carry out FFT calculates.

Validator 240 is coupled to correlator 210, is used for being correlated with according to symbol verifying symbol.Described symbol is one of in leading symbol and the data symbol.If described symbol is a leading symbol, then can obtain frame synchronization.

No matter symbol after testing is leading symbol or data symbol, is all handled by post-processing unit 250 subsequently.Post-processing unit 250 comprises other parts of the receiver among the MS 140, is used to carry out the receiver task, eliminates, uses FFT to carry out data recovery, channel equalization, channel estimating, decoding, deinterleaving or the like such as CP.

Fig. 3 shows that time domain according to an embodiment of the invention is relevant 320, the diagram of frequency domain relevant 330.Relevant is that the symbol sebolic addressing 310 that receives is carried out.

Given sequence x (n), come being correlated with of sequence of calculation x (n) according to following formula:

$R_x\left(n\right)=\underset{n=0}{\overset{N_g-1}{\mathrm{\Σ}}}x\left(n\right)\·x^{*}(n+N_{\mathrm{FFT}})---\left(1\right)$

Wherein, x (n) is the sequence that receives in time domain, N _FFTBe counting of FFT calculating.

In time domain, the conjugation symmetry is described as:

y(n)＝y ^*(N _FFT-n) (2)

Wherein, y ^*It is the complex conjugate of y.

In view of the above, the detection of preamble based on the conjugation symmetry can be configured to:

$r_{\mathrm{cs}}\left(k\right)=|\underset{n=1}{\overset{n=L}{\mathrm{\Σ}}}y(k+n)\·y(k+N_{\mathrm{FFT}}-n)|---\left(3\right)$

Wherein, L is the length or the size of correlation window, and it is less than N _FFT/ 2.

In time domain is relevant, suppose n ₀Be the starting position of the useful part of the symbol sebolic addressing that obtains from the detection based on CP, equation (3) can be configured to so:

$r_{\mathrm{CS}}(n_0+k)=|\underset{n=1}{\overset{n=L}{\mathrm{\Σ}}}y(n_0+k+n)\·y(n_0+k+N_{\mathrm{FFT}}-n)|---\left(4\right)$

Wherein, k=-K _W.., K _W, K=2K _WThe+1st, the length of checking window.

Thus, the relevant 2K that only calculates of time domain _W+ 1 conjugation symmetry is relevant, rather than it is relevant to calculate whole L conjugation symmetries.Correspondingly, calculation times is less than the calculation times of standard technique.

The relevant equation (4) that uses of time domain comes compute sign relevant.This computational process can illustrate by time domain shown in Figure 3 relevant 320.In time domain relevant 320, sequence that receives and conjugation symmetry thereof are to opposite shift reverse.

In frequency domain is relevant, according to as described below, the relevant circular convolution that is converted to that will in equation (4), provide.Equation (4) can be regarded as the relevant of two sequence S1 and S2.For each different k value, according to the symbol of k, sequence S1 is to shifting left or right shift, S2 right shift or to shifting left.Yet as k during much smaller than L, the most elements in the different sequences is identical.According to this observed result, equation (4) can be approximated to be:

$r_{\mathrm{CS}}(n_0+k)\≈|\underset{n=1}{\overset{n=L}{\mathrm{\Σ}}}x(n_0+n)\·x\left({\⟨n_0+k+N_{\mathrm{FFT}}-n\⟩}_L\right)|---\left(5\right)$

Wherein,＜〉 _LThe mould of expression L.

From equation (5) as can be seen, for different k values, sequence S1 fixes; According to the value of k, sequence S2 is a cyclic shift.This can illustrate by frequency domain relevant 330.

Equation (5) can be regarded as the circular convolution of two sequences.Be without loss of generality, for the sake of simplicity, suppose n ₀Be 0.Sequence S1 and S2 are rewritten as:

S1＝[x(1)x(2)…x(L)]， (6a)

S2＝[x(N _FFT-1)x(N _FFT-2)…x(N _FFT-L)]， (6b)

R _CS＝[r _CS(1)r _CS(2)…r _CS(L)]， (6c)

Wherein, R _CSBe the convolution of S1 and S2, so:

$R_{\mathrm{cs}}\&ap;\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="A200780041344E00331.png"\; state="\{\{state\}\}">S</figure-callout>}1\&CircleTimes;S2=\mathrm{IFFT}(\mathrm{FFT}\left(S1\right)\&CenterDot;{\left(\mathrm{FFT}\left({S2}^{*}\right)\right)}^{*})---\left(7\right)$

S1 is-symbol sequence x (n)=[x (1) x (2) ..., x (N _FFT-1), x (N _FFT)] in first sequence.S2 is second sequence S ' 2=[x (N _FFT-L), x (N _FFT-(L+1)) ..., x (N _FFT-1), x (N _FFT)] retracing sequence.Although it should be noted that frequency domain is relevant has used twice FFT and an IFFT, this does not bring extra amount of calculation to the receiver among the MS140, because FFT and IFFT computing have been implemented in the OFDM transceiver.

In addition, though the relevant size that increases the checking window of frequency domain does not increase the complexity of calculating.In time domain is relevant, computation complexity and checking window size K _wProportional.In frequency domain was relevant, the checking window size can be L/4.

In addition, frequency-domain correlation has increased processing gain with less relatively complexity overhead.Processing gain and correlation window size L are proportional.When window size when L is increased to 2L, the time domain Processing Algorithm needs extra (2K _w+ 1) * L complex multiplication, and frequency-domain correlation only needs L time extra complex multiplication.As mentioned above, the extra computing relevant with FFT/IFFT can be ignored, because these computings can not gone into new hardware to receiving power traction.

In addition, the correlation technique in the embodiment of the invention provides character boundary estimation accurately under the situation of no overhead.Conventional border estimation is based on Cyclic Prefix, and wherein, correlation function is a trigonometric function.The border is to estimate according to the peak of triangle.Because the influence of various disturbing factors, it is very inaccurate that the border is estimated.On the other hand, be increment (δ) function based on the relevant of conjugation symmetry, this means that time measure is high a lot of at the peak value of peakedness ratio in other position of symbol time position accurately.Thus, this scheme can provide than estimating based on the accurately a lot of border of the scheme of CP.

Fig. 4 shows the diagram of the frequency-domain correlator 230 shown in Fig. 2 according to an embodiment of the invention.Frequency-domain correlator 230 comprises: acoustic convolver 410 and contrary FT module 460.The parts that frequency-domain correlator 230 comprises can also can be less than above-mentioned parts more than above-mentioned parts.

The frequency-domain circular convolution of frequency-domain convolver 410 compute sign sequences.Frequency-domain convolver 410 comprises: a FT module 420, rearrangement and complex conjugate operator 430, the 2nd FT module 440, complex conjugate operator 445 and multiplier 450.The one FT module 420 is used for the FT sequence of the first sequence S1 of compute sign sequence, and wherein, the length of the first sequence S1 is the length L of correlation window.Rearrangement and complex conjugate operator 430 are used for the second sequence S ' 2 of symbol sebolic addressing is carried out rearrangement and complex conjugate operation.Rearrangement and complex conjugate operator 430 comprise the index mapper, and the latter is used for index is mapped to symmetrical index, shown in equation (6b) and (7).The 2nd FT sequence that the 2nd FT module 440 is calculated through second sequence after rearrangement and the complex conjugate, the length of second sequence after process rearrangement and the complex conjugate is the length L of correlation window.The output result of 445 couples the 2nd FT440 of complex conjugate operator carries out complex conjugate operation.The two FT sequence of multiplier 450 after with a FT sequence and complex conjugate multiplies each other, so that frequency-domain circular convolution to be provided.

Inverse Fourier transform (FT) module 460 is couple to acoustic convolver 410, is used for the inverse Fourier transform (FT) of computation cycles convolution, thereby provides symbol relevant.As a rule, a FT module and the 2nd FT module adopt FFT to carry out FT calculating.Contrary FT module 460 adopts IFFT to carry out contrary FT and calculates.

Fig. 5 shows according to an embodiment of the invention, shown in figure 2 the diagram of validator 240.Validator 240 comprises: peak detector 510, adder 520, first comparator 530 and second comparator 540, detector 550.The parts that validator 240 comprises can also can be less than above-mentioned parts more than above-mentioned parts.

Peak detector 510 definite symbols are correlated with at maximum position k ₀The maximum at 515 places.K maximum during the also definite symbol of peak detector 510 is relevant, wherein, K is the positive integer of being scheduled to.Thus, peak detector 510 can be used for carrying out two class functions: a class is to determine maximum; Another kind of is to determine K maximum, and wherein, K maximum comprised maximum.K peaked summation during adder 520 compute signs are relevant.A described K maximum comprises maximum position k ₀The maximum at 515 places.First comparator 530 is with maximum and first threshold TH ₁535 compare.Second comparator 540 is with the summation and the second threshold value TH ₂545 compare.

If maximum has surpassed first threshold TH ₁, then detector 550 is with maximum position k ₀The symbol detection at place is a leading symbol.Work as k ₀During≤L/2, according to the detection based on CP, the index corresponding with the original position of leading useful part is positioned at the right side of the character boundary that is detected, and perhaps index is (n ₀+ k ₀/ 2).Work as k ₀During L/2, the index corresponding with the original position of leading useful part is positioned at the left side of the character boundary that is detected, perhaps index is (n ₀-(L-k ₀)/2).If summation has surpassed the second threshold value TH ₂, then detector 550 is a leading symbol with symbol detection also.As the situation of first threshold, original position is according to k ₀Calculate.

If maximum does not surpass first threshold TH ₁535 and summation surpass the second threshold value TH ₂545, then detector 550 is a data symbol with symbol detection, or detector 550 is announced authentication failed.If one of at least indicated maximum in comparator 530 and 540 greater than TH ₁Or indicated summation greater than TH ₂, then detector 550 can be to have announced with symbol detection to be the logical circuit of leading symbol.If comparator 530 and 540 has all indicated the neither one threshold value to be exceeded, then detector 550 is announced authentication failed, or does not detect leading symbol.

Fig. 6 shows the flow chart of processing procedure 600 according to an embodiment of the invention, and this processing procedure is used to detect leading and synchronous.

After beginning, processing procedure 600 is used the relevant and symbol of compute sign sequence be correlated with (square frame 610) one of during frequency domain is relevant of time domain in correlation window L.Symbol sebolic addressing receives in OFDM (OFDMA) radio communication.Next, processing procedure 600 is correlated with according to symbol and is verified symbol (square frame 620), and then, processing procedure 600 stops.Described symbol is one of in leading symbol and the data symbol.Proof procedure is used for verifying whether sequence exists leading symbol.If do not detect leading symbol, then proof procedure generates the result of failure, and described processing procedure is waited for detection time next time.

Fig. 7 A shows the flow chart of processing procedure 610 shown in Figure 6 according to an embodiment of the invention, and processing procedure 610 is used to use time domain correlation computations symbol relevant.Processing procedure 610 uses the conjugate symmetric sequence compute sign relevant in checking window K.Checking window K is less than correlation window L.

After beginning, processing procedure 610 initialization index k are-K _w(square frame 710).Next, processing procedure 610 is used the relevant R of equation (4) compute sign _CS(k) (square frame 715).Subsequently, processing procedure 610 is upgraded index k, for example, k=k+1 (square frame 720) is set.Next, processing procedure 610 judges whether k has surpassed largest index K _w(square frame 725).If do not surpass largest index K _w, then processing procedure 610 is returned square frame 715, and it is relevant to continue compute sign.Otherwise processing procedure 610 stops.

Fig. 7 B shows the flow chart of processing procedure 610 shown in Figure 6 according to an embodiment of the invention, and processing procedure 610 uses frequency domains to be correlated with compute sign relevant.

After beginning, the frequency-domain circular convolution of processing procedure 610 compute sign sequences (square frame 730).Next, the inverse Fourier transform (FT) that processing procedure 610 is calculated this circular convolution is correlated with by (square frame 760) so that symbol to be provided, and then, processing procedure 610 stops.

Processing procedure 730 can be carried out according to following steps.At first, a FT sequence of first sequence in the processing procedure 730 compute sign sequences, wherein, the length of first sequence is the length L (square frame 735) of correlation window.First sequence is at the sequence S1 shown in the equation (6a).Next, process rearrangement in processing procedure 730 definite symbol sebolic addressings and second sequence (square frame 740) after the complex conjugate.Second sequence is S ' 2 sequences.This relates to carries out the mapping of rearrangement index to second sequence, and second sequence after resetting is carried out complex conjugate operation.Second sequence after the rearrangement is the sequence S2 in the equation (6b).Subsequently, the 2nd FT sequence that processing procedure 730 is calculated through second sequence after rearrangement and the complex conjugate, wherein, the length of second sequence after process rearrangement and the complex conjugate is the length L (square frame 745) of correlation window.Next, 730 pairs the 2nd FT sequences of processing procedure are carried out complex conjugate operation (square frame 750).Then, the two FT sequence of processing procedure 730 after with a FT sequence and complex conjugate multiplies each other, and so that frequency-domain circular convolution (square frame 750) to be provided, then, processing procedure 730 stops.

Fig. 8 shows the flow chart of processing procedure 620 shown in Figure 6 according to an embodiment of the invention, and this processing procedure is used to verify symbol.

After beginning, processing procedure 620 definite symbols are correlated with at maximum position k ₀The maximum C at place _Max(square frame 810).Next, processing procedure 620 calculating central position k _cThe summation S (square frame 820) of the relevant value of the symbol at location about place.Then, processing procedure 620 is with maximum and first threshold TH ₁Compare (square frame 830).Next, processing procedure 620 is with the summation and the second threshold value TH ₂Compare (square frame 840).Order that it should be noted that square frame 830 and 840 is unimportant.

Subsequently, processing procedure 620 is judged maximum C _MaxWhether greater than first threshold TH ₁Perhaps whether summation S is greater than the second threshold value TH ₂(square frame 850).If really so, then processing procedure 620 is determined maximum position k ₀The symbol at place is leading symbol (if C _MaxGreater than first threshold TH ₁), perhaps, processing procedure 620 determines that the symbol of center position is that leading symbol is (if summation S is greater than the second threshold value TH ₂), then, processing procedure 620 stops.Otherwise, also, if maximum C _MaxSurpass first threshold, and summation S surpasses second threshold value, then processing procedure 620 determines that symbols are data symbol or announce authentication failed.Then, processing procedure 620 stops.

Fig. 9 shows the diagram of processing unit 900 according to an embodiment of the invention, and processing unit 900 is used to carry out detection of preamble shown in Figure 1 and synchronous 145 _i Processing unit 900 comprises: processor 910, storage control (MC) 920, main storage 930, i/o controller (IOC) 940, interconnection 945, mass storage interface 950, I/O (I/O) equipment 947 ₁To 947 _K, network interface unit (NIC) 960.The parts that processing unit 900 comprises can also can be less than above-mentioned parts more than above-mentioned parts.

The CPU of processor 910 expression any structure types, such as the processor that uses hyperthread, safety, network, digital media technology, single core processor, polycaryon processor, flush bonding processor, mobile processor, microcontroller, digital signal processor, superscalar computer, vector processor, single-instruction multiple-data (SIMD) computer, complex instruction set computer (CISC) (CISC), Reduced Instruction Set Computer (RISC), very long instruction word (VLIW) or mixed architecture.

MC 920 is used for control and config memory and input-output apparatus (such as main storage 930 and IOC 940).MC 920 can be integrated in the chipset, and wherein, this chipset is integrated such as the multiple function of figure, medium, isolated execution pattern, host to peripheral bus interface, storage control, power management etc.Storage control functive among MC 920 or the MC 920 can be integrated in the processor unit 910.In certain embodiments, no matter storage control is in the inside of processor unit 910, still in the outside of processor unit 910, all can be used for whole cores or processor in the processor unit 910.In other embodiments, storage control comprises the different piece that is respectively applied for different core in the processor unit 910 or processor.

Main storage 930 is used for stores system code and data.Main storage 930 adopts the memory (comprising that those do not need the memory that refreshes) of dynamic random access memory (DRAM), static RAM (SRAM) or any other type to realize usually.Main storage 930 can comprise a plurality of passages such as the memory device of DRAM.DRAM comprises that bandwidth is double data rate (DDR) (DDR2) equipment of 8.5G byte per second (GB/s).In one embodiment, memory 930 comprises preamble detection/synchronization module 935.Preamble detection/synchronization module 935 can be used for carrying out repertoire or some functions in the function mentioned above.

IOC 940 possesses the some functions that are used to support the I/O function.IOC 940 can also be integrated in the chipset with MC9 20, also can separate with MC 920, to carry out the I/O function.IOC 940 comprises some interfaces and I/O function, such as peripheral component interconnect (pci) bus interface, processor interface, interrupt control unit, direct memory visit (DMA) controller, Power management logic, timer, System Management Bus (SMBus), USB (USB) interface, mass storage interface, low pin number (LPC) interface, radio interconnected, direct media interface (DMI) etc.

Interconnection 945 interfaces that provide ancillary equipment.Interconnection 945 can be point-to-point, also can be connected to a plurality of equipment.For simplicity's sake, not shown whole interconnection.Can expect, interconnection 945 can comprise any interconnection or bus, such as peripheral component interconnect (pci), PCI high speed, USB (USB), small computer system interface (SCSI), serial SCSI and direct media interface (DMI) etc.

Mass storage interface 950 is connected to mass memory unit, with the archive information of storage such as code, program, file, data and application.Mass storage interface comprises that SCSI, serial SCSI, advanced techniques connect (ATA) (parallel and/or serial), integrated drive electronics (IDE), strengthen IDE, ATA packet interface (ATAPI) etc.Mass memory unit comprises the high-capacity and high-speed storage array, such as Redundant Array of Inexpensive Disc (RAID), network attached storage (NAS), digital magnetic tape, light storage device or the like.

Mass memory unit comprises that compact disk (CD) read-only memory (ROM) 952, digital video/multifunctional optical disk (DVD) 953, floppy drive are moving 954, hard-drive 955, magnetic tape drive 956 and any other magnetic storage apparatus or light storage device.Mass memory unit provides a kind of mechanism of read machine-accessible media.

I/O equipment 947 ₁To 947 _KComprise any I/O equipment that is used to carry out the I/O function.I/O equipment 947 ₁To 947 _KExample comprise: controller, media card (for example, audio frequency, video, figure) and any other peripheral controllers of being used for input equipment (for example, keyboard, mouse, tracking ball, positioning equipment).

NIC 960 provides network-in-dialing to processing unit 230.NIC 960 generates and interrupts, as the part of communication service processing.In one embodiment, NIC 960 and 32 peripheral component interconnect (pci) bus standards and 64 peripheral component interconnect (pci) bus standard compatibilities.NIC 960 as a rule follows PCI local bus version 2 .2, PCI-X local bus version 1.0 or PCI high speed modular.In treatment system, can exist more than a NIC 960.As a rule, NIC 960 supports standard ethernet minimum and largest frames size (64 to 6518 byte), frame format, institute of electrical and electronic engineers (IEEE) 802.2 link-locals to control (LLC) standard.NIC 960 also supports the full duplex gigabit ethernet interface, based on the flow control of frame with defined other standard of wired ethernet physical layer and data link layer.NIC 960 can support defined copper cash gigabit Ethernet of IEEE 802.3ab or the defined optical fiber gigabit Ethernet of IEEE 802.3z.

NIC 960 can also be host bus adaptor (HBA), such as small computer system interface (SCSI) host adapter or fiber channel (FC) host adapter.Scsi host adapter comprises: hardware on the plate and firmware are used to carry out the SCSI business; Adapter basic input/output (BIOS) is used for starting or being used to dispose scsi host adapter from scsi device.The FC host adapter can be used for being interfaced to the fiber channel bus.The FC host adapter can (for example, 2Gbps) work be carried out auto-speed with fibre channel storage area network (SAN) and is consulted at a high speed.The FC host adapter is supported by suitable firmware or software, so that provide having discovery, report and the management of the local and remote HBA that is with interior FC or the outer Internet protocol of band (IP) support.The FC host adapter has: the reorganization of multiplexing, the unordered frame of frame rank, be used to construct context cache on the plate of support, have the end-to-end data protection that hardware check and cyclic redundancy code (CRC) are supported.

Key element in one embodiment of the present of invention can use hardware, firmware, software or their combination in any to realize.Term " hardware " is commonly referred to as the element with physical structure, such as electronic device, electromagnetic device, optics, photoelectric device, mechanical devices, electromechanical device or the like.Hardware realizes comprising circuit, equipment, processor, application-specific integrated circuit (ASIC) (ASIC), programmable logic device (PLD), field programmable gate array (FPGA) or any electronic equipment.Term " software " is commonly referred to as logical construction, method, process, program, routine, processing, algorithm, formula, function, expression formula or the like.Term " firmware " is commonly referred to as logical construction, method, process, program, routine, processing, algorithm, formula, function, expression formula or the like, and it realizes or be embedded in (for example, flash memories, ROM, EPROM) in the hardware configuration in hardware configuration.The example of firmware comprises microcode, can write control store, little programming structure.When using software or firmware to realize, the key element of embodiments of the invention is the code segment that is used to carry out necessary task in essence.Software/firmware comprises and is used to carry out the actual code of one embodiment of the present of invention the operation described or is used for emulation or excites the code of operation.Program or code segment can be stored in the processor, also can be stored in the machine accessible medium, also can send on transmission medium by being embodied in the signal that computer data signal in the carrier wave or carrier wave modulate." the readable or accessible of processor " or " machine readable or accessible " comprise any medium that can store, send or transmit information.The example of processor readable medium or machine accessible medium comprises electronic circuit, semiconductor memory apparatus, read-only memory (ROM), flash memories, erasable programmable ROM (EPROM), floppy disk, compact disk (CD) ROM, CD, hard disk, fiber medium, radio frequency (RF) link or the like.Computer data signal comprises any signal that can propagate on the transmission medium such as electronic network channels, optical fiber, aerial, electromagnetism, RF link etc.Code segment can be via downloading such as the computer network of the Internet, Intranet etc.Machine accessible medium can be included in the manufacture.Machine accessible medium comprises information or data, and when these information of machine access or data, these information or data make machine carry out operation as described above or action.Machine accessible medium also comprises embedding program code wherein.Program code comprises the machine readable code that is used to carry out operation as described above or action.Term herein " information " or " data " refer to the information that coding is used for any kind of machine readable purposes.Thus, " information " or " data " comprises program, code, data, file or the like.

Depend on the application according to special characteristic, function, all or part of of embodiments of the invention can be realized in several ways.These modes comprise hardware, software, firmware or their combination in any.Hardware, software or firmware components comprise the plurality of modules that is coupled to each other.Hardware module is couple to another module by machinery, electricity, light, electromagnetism or any physical connection.Software module is returned etc. by function, process, method, subprogram or subroutine call, redirect (jump), link, parameter, variable, argument transmission, function and is couple to another module.Software module is couple to another module, so that receive variable, parameter, argument, pointer etc. and/or generate or transmit variable, pointer of result, renewal or the like.Firmware module is couple to another module by the combination in any of above-mentioned hardware coupling method and software coupling method.Hardware, software or firmware module can be couple to any one in another hardware, software or the firmware module.Module can also be software-driven or interface, to carry out alternately with the operating system of moving on platform.Module can also be a hardware driving, is used for configuration, setting, initiating hardware equipment, sends data and receive data from hardware device to hardware device.Device comprises the combination in any of hardware, software and firmware module.

Though described the present invention according to some embodiment, it will be appreciated by those skilled in the art that the present invention is not limited to described these embodiment, but can in the spirit and scope of claims, the present invention be made amendment and change.Thereby it is illustrative, and not restrictive that described description should be regarded as.

Claims (27)

1, a kind of method comprises:

In correlation window, use time domain relevant and come the symbol of compute sign sequence to be correlated with one of during frequency domain is relevant, wherein, described symbol sebolic addressing receives in OFDM (OFDMA) radio communication;

Be correlated with according to described symbol and verify symbol, wherein, described symbol is one of in leading symbol and the data symbol.

2, method according to claim 1, wherein, use described time domain to be correlated with to calculate that described symbol is relevant comprises:

In the checking window, it is relevant to use conjugate symmetric sequence to calculate described symbol, and wherein, described checking window is less than described correlation window.

3, method according to claim 1, wherein, use described frequency domain to be correlated with to calculate that described symbol is relevant comprises:

Calculate the frequency-domain circular convolution of described symbol sebolic addressing;

Calculate the inverse Fourier transform (FT) of described circular convolution, relevant so that described symbol to be provided.

4, method according to claim 3, wherein, calculate described frequency-domain circular convolution and comprise:

Calculate a FT sequence of first sequence in the described symbol sebolic addressing, wherein, the length of described first sequence is the length of described correlation window;

Second sequence in the described symbol sebolic addressing is carried out rearrangement and complex conjugate operation;

Calculate the 2nd FT sequence through second sequence after rearrangement and the complex conjugate, wherein, the length of second sequence after process rearrangement and the complex conjugate is the length of described correlation window;

Described the 2nd FT sequence is carried out complex conjugate operation;

The 2nd FT sequence after a described FT sequence and the described complex conjugate is multiplied each other, so that described frequency-domain circular convolution to be provided.

5, method according to claim 1, wherein, verify that described symbol comprises:

Determine that described symbol is correlated with in the maximum at maximum position place;

Calculate the relevant K of a described symbol peaked summation, wherein, a described K maximum comprises the maximum at described maximum position place;

Described maximum and first threshold are compared;

The described summation and second threshold value are compared;

If described maximum has surpassed described first threshold or described summation has surpassed described second threshold value, determine that then the symbol at described maximum position place is a leading symbol;

If described maximum does not surpass described first threshold and described summation and do not surpass described second threshold value, determine that then described symbol is a data symbol.

6, method according to claim 4, wherein, one of calculate in a described FT sequence and described the 2nd FT sequence and to comprise:

One of in use fast Fourier transform (FFT) described FT sequence of calculating and described the 2nd FT sequence.

7, method according to claim 3, wherein, calculate described contrary FT and comprise:

Use inverse fast fourier transform (IFFT) to calculate described contrary FT.

8, a kind of device comprises:

Correlator is used at correlation window, one of uses in time domain correlator and the frequency-domain correlator to come the symbol of compute sign sequence relevant, and wherein, described symbol sebolic addressing receives in OFDM (OFDMA) radio communication;

Validator is couple to described correlator, is used for being correlated with according to described symbol verifying symbol, and wherein, described symbol is one of in leading symbol and the data symbol.

9, device according to claim 8, wherein, described time domain correlator is in the checking window, and it is relevant to use conjugate symmetric sequence to calculate described symbol, and wherein, described checking window is less than described correlation window.

10, device according to claim 8, wherein, described frequency-domain correlator comprises:

Frequency-domain convolver is used to calculate the frequency-domain circular convolution of described symbol sebolic addressing;

Inverse Fourier transform (FT) module is couple to described acoustic convolver, is used to calculate the inverse Fourier transform (FT) of described circular convolution, and is relevant so that described symbol to be provided.

11, device according to claim 10, wherein, described acoustic convolver comprises:

The one FT module is used for calculating a FT sequence of first sequence of described symbol sebolic addressing, and wherein, the length of described first sequence is the length of described correlation window;

First complex conjugate operator is used for second sequence of described symbol sebolic addressing is carried out rearrangement and complex conjugate operation;

The 2nd FT module is used to calculate the 2nd FT sequence through second sequence after rearrangement and the complex conjugate, and wherein, the length of second sequence after process rearrangement and the complex conjugate is the length of described correlation window;

Second complex conjugate operator is used for described the 2nd FT sequence is carried out complex conjugate operation;

Multiplier is used for the 2nd FT sequence after a described FT sequence and the described complex conjugate is multiplied each other, so that frequency-domain circular convolution to be provided.

12, device according to claim 8, wherein, described validator comprises:

Peak detector is used for definite described symbol and is correlated with in the maximum at maximum position place;

Adder is used to calculate the relevant K of a described symbol peaked summation, and wherein, a described K maximum comprises the maximum at described maximum position place;

First comparator is used for described maximum and first threshold are compared;

Second comparator is used for the described summation and second threshold value are compared;

Detector is used for:

If described maximum has surpassed described first threshold or described summation has surpassed described second threshold value, then the symbol detection with described maximum position place is a leading symbol;

If described maximum does not surpass described first threshold and described summation and does not surpass described second threshold value, is data symbol with described symbol detection then.

13, a kind of manufacture comprises:

Machine accessible medium comprises data, and when the described data of machine access, the operation that described data make described machine carry out comprises:

In correlation window, use time domain relevant and come the symbol of compute sign sequence to be correlated with one of during frequency domain is relevant, wherein, described symbol sebolic addressing receives in OFDM (OFDMA) radio communication;

Be correlated with according to described symbol and verify symbol, wherein, described symbol is one of in leading symbol and the data symbol.

14, manufacture according to claim 13, wherein, make described machine use described time domain to be correlated with to calculate the relevant described data of described symbol to comprise when described machine is visited it, make described machine carry out the data of following operation, wherein, described operation comprises:

In the checking window, it is relevant to use conjugate symmetric sequence to calculate described symbol, and wherein, described checking window is less than described correlation window.

15, manufacture according to claim 13, wherein, make described machine use described frequency domain to be correlated with to calculate the relevant described data of described symbol to comprise when described machine is visited it, make described machine carry out the data of following operation, wherein, described operation comprises:

Calculate the frequency-domain circular convolution of described symbol sebolic addressing;

Calculate the inverse Fourier transform (FT) of described circular convolution, relevant so that described symbol to be provided.

16, manufacture according to claim 15, wherein, the described data that make described machine calculate described frequency-domain circular convolution comprise when described machine is visited it, make described machine carry out the data of following operation, wherein, described operation comprises:

Calculate a FT sequence of first sequence in the described symbol sebolic addressing, wherein, the length of described first sequence is the length of described correlation window;

Second sequence in the described symbol sebolic addressing is carried out rearrangement and complex conjugate operation;

Calculate the 2nd FT sequence through second sequence after rearrangement and the complex conjugate, wherein, the length of second sequence after process rearrangement and the complex conjugate is the length of described correlation window;

Described the 2nd FT sequence is carried out complex conjugate operation;

The 2nd FT sequence after a described FT sequence and the described complex conjugate is multiplied each other, so that frequency-domain circular convolution to be provided.

17, manufacture according to claim 13 wherein, makes the described data of described machine checking symbol comprise that when described machine is visited it make described machine carry out the data of following operation, wherein, described operation comprises:

Determine that described symbol is correlated with in the maximum at maximum position place;

Calculate the relevant K of a described symbol peaked summation, wherein, a described K maximum comprises the maximum at described maximum position place;

Described maximum and first threshold are compared;

The described summation and second threshold value are compared;

If described maximum has surpassed described first threshold or described summation has surpassed described second threshold value, determine that then the symbol at described maximum position place is a leading symbol;

If described maximum does not surpass described first threshold and described summation and do not surpass described second threshold value, determine that then described symbol is a data symbol.

18, a kind of device comprises:

Symbol correlation computations module is used at correlation window, uses time domain relevant and come the symbol of compute sign sequence to be correlated with one of during frequency domain is relevant, and wherein, described symbol sebolic addressing receives in OFDM (OFDMA) radio communication;

The validation symbol module is used for being correlated with according to described symbol and verifies symbol, and wherein, described symbol is one of in leading symbol and the data symbol.

19, device according to claim 18, wherein, use time domain to be correlated with to calculate the relevant module of described symbol to comprise:

Be used for using conjugate symmetric sequence to calculate the relevant module of described symbol at the checking window, wherein, described checking window is less than described correlation window.

20, device according to claim 18, wherein, use frequency domain to be correlated with to calculate the relevant module of described symbol to comprise:

The frequency-domain circular convolution computing module is used to calculate the frequency-domain circular convolution of described symbol sebolic addressing;

The inverse Fourier transform computing module, the inverse Fourier transform (FT) that is used to calculate described circular convolution is relevant so that described symbol to be provided.

21, device according to claim 20, wherein, described circular convolution computing module comprises:

The one FT sequence computing module is used for calculating a FT sequence of first sequence of described symbol sebolic addressing, and wherein, the length of described first sequence is the length of described correlation window;

First complex conjugate module is used for second sequence of described symbol sebolic addressing is carried out rearrangement and complex conjugate operation;

The 2nd FT sequence computing module is used to calculate the 2nd FT sequence through the sequence after rearrangement and the complex conjugate, and wherein, the length of the sequence after process rearrangement and the complex conjugate is the length of described correlation window;

Second complex conjugate module is used for described the 2nd FT sequence is carried out complex conjugate operation;

Multiplier module is used for the 2nd FT sequence after a described FT sequence and the described complex conjugate is multiplied each other, so that frequency-domain circular convolution to be provided.

22, device according to claim 18, wherein, described validation symbol module comprises:

The maximum determination module is used for definite described symbol and is correlated with in the maximum at maximum position place;

The summation computing module is used to calculate the relevant K of a described symbol peaked summation, and wherein, a described K maximum comprises the maximum at described maximum position place;

First comparison module is used for described maximum and first threshold are compared;

Second comparison module is used for the described summation and second threshold value are compared;

The leading symbol determination module is used for: if described maximum has surpassed described first threshold or described summation has surpassed described second threshold value, determine that then the symbol at described maximum position place is a leading symbol;

The data symbol determination module is used for: do not surpass described second threshold value if described maximum surpasses described first threshold and described summation, determine that then described symbol is a data symbol.

23, a kind of mobile radio station (MS) comprising:

Radio frequency (RF) receiver is used for that (BS) receives the wireless signal carry symbol sebolic addressing from the base station in OFDM (OFDMA) radio communication;

Preamble detector and synchronizer are couple to described RF receiver, and wherein, described preamble detector and synchronizer comprise:

Correlator is used at correlation window, one of uses in time domain correlator and the frequency-domain correlator to come the symbol of compute sign sequence relevant;

Validator is couple to described correlator, is used for being correlated with according to described symbol verifying symbol, and wherein, described symbol is one of in leading symbol and the data symbol.

24, MS according to claim 23, wherein, described time domain correlator is in the checking window, and it is relevant to use conjugate symmetric sequence to calculate described symbol, and wherein, described checking window is less than described correlation window.

25, MS according to claim 23, wherein, described frequency-domain correlator comprises:

Frequency-domain convolver is used to calculate the frequency-domain circular convolution of described symbol sebolic addressing;

Inverse Fourier transform (FT) module is couple to described acoustic convolver, is used to calculate the inverse Fourier transform (FT) of described circular convolution, and is relevant so that described symbol to be provided.

26, MS according to claim 25, wherein, described acoustic convolver comprises:

The one FT module is used for calculating a FT sequence of first sequence of described symbol sebolic addressing, and wherein, the length of described first sequence is the length of described correlation window;

First complex conjugate operator is used for second sequence of described symbol sebolic addressing is carried out rearrangement and complex conjugate operation;

The 2nd FT module is used to calculate the 2nd FT sequence through second sequence after rearrangement and the complex conjugate, and wherein, the length of second sequence after process rearrangement and the complex conjugate is the length of described correlation window;

Second complex conjugate operator is used for described the 2nd FT sequence is carried out complex conjugate operation;

Multiplier is used for the 2nd FT sequence after a described FT sequence and the described complex conjugate is multiplied each other, so that frequency-domain circular convolution to be provided.

27, MS according to claim 23, wherein, described validator comprises:

Peak detector is used for definite described symbol and is correlated with in the maximum at maximum position place;

Adder is used to calculate the relevant K of a described symbol peaked summation, and wherein, a described K maximum comprises the maximum at described maximum position place;

First comparator is used for described maximum and first threshold are compared;

Second comparator is used for the described summation and second threshold value are compared;

Detector is used for:

If described maximum has surpassed described first threshold or described summation has surpassed described second threshold value, then the symbol detection with described maximum position place is a leading symbol;

If described maximum does not surpass described first threshold and described summation and does not surpass described second threshold value, is data symbol with described symbol detection then.

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