CN1878386A - Cell recognition method for OFDMA cellular system - Google Patents

Abstract

The invention relates to a method of region recognition used in OFDMA beehive system, belonging to the communication technique. Wherein, each frame only needs one OFDM mark as the synchronous signal channel data, with the advantage of synchronous signal channel data as low consumption, while the peak average power rate of said mark is low; in addition, using the cascade region recognition, using the mode pictures of different sub carrier waves loaded by data, to recognize different region number groups; and using the frequency difference sequence of nearby sub carrier wave with loaded data, to recognize the different region numbers. The invention uses multi-mark judge, with large recognized region number, low calculation complexity, low error rate, and high application value.

Description

A kind of method that is applied to the cell identification of OFDMA cellular system

Technical field

The present invention relates to a kind of method of identification of communication technical field, specifically is the method for the cell identification of a kind of OFDMA of being applied to (orthogonal frequency division multiplexing multiple access) cellular system.

Background technology

OFDM (OFDM) technology is applied at increasing wired, wireless communication field, and this has many advantages mainly due to the OFDM technology: effectively anti-multipath is disturbed and narrow band interference, and availability of frequency spectrum height, message transmission rate is high.At present, the OFDM technology has been defined as the one preferred technique of the middle down link of EUTRA (universal mobile telecommunications system of evolution and continental rise radio insert) and EUTRAN (the universal mobile telecommunications system net of evolution and continental rise radio access network) (perhaps be called Super 3G: super 3 g mobile communication system) by 3GPP tissue (3G (Third Generation) Moblie partner plan) international organization.In the cellular system based on the OFDMA technology, user terminal is when powering up, and is the same with the cellular system of W-CDMA technology when standby or conversation, must search for its affiliated Cell searching.In the cell search scheme of the cellular system of OFDMA technology, except since the data-modulated mode different with W-CDMA, need FFT (Fast Fourier Transform, fast Fourier transform) window is used for recovering outside the modulated data synchronously, other aspects and W-CDMA three steps cell search scheme are similar, so it comprises following three steps: carrier frequency synchronization and FFT time window are synchronous, frame synchronization, cell identification.Through the file of prior art is looked into newly, find that most technology have only solved frame synchronization and carrier frequency synchronization, and do not relate to the cell identification problem of OFDMA cellular system.

In only documents, the OFDMA cellular system at EUTRA requires has three kinds of methods to can be used for the OFDMA cell identification:

(1) determines that in each frame 1 OFDM symbol as synchronization channel symbols, loads special sequence at frequency domain,, reach the purpose of cell identification by this frequency domain sequence of Direct Recognition.Referring to document: 3GPP, R1-051329, " Cell Search and Initial Acquisition for OFDM Downlink ", Motorola.(3GPP document, numbering: R1-051329, motorola inc, " Cell searching of OFDM down link and initial synchronisation ")

(2) determine that in each frame n (n is generally the natural number more than or equal to 4) OFDM symbol as synchronization channel symbols, loads special sequence on frequency domain.The corresponding code word of each frequency domain sequence, the corresponding cell id code character of the particular combinations of n code word (or being called cell scrambling number group), total x _GIndividual cell id code character obtains sub-district number (or be called cell scrambling number), total x by being similar to CPICH (Common Pilot Channel) among the WCDMA then _IIndividual sub-district number.So this method can be discerned x altogether _Gx _IIndividual different sub-district.Referring to document: 3GPP, R1-060072, ETRI, " Cell Search Scheme for EUTRA﹠amp; TP ".(3GPP document, numbering: R1-060072, ETRI company, " being applied to cell search scheme and the literal suggestion of EUTRA ")

(3) determine that in each frame n (n is generally the natural number more than or equal to 5) OFDM symbol as synchronization channel symbols, loads the data sequence through chnnel coding on frequency domain,, reach the purpose of cell identification by these data of demodulation sign indicating number.Referring to document: 3GPP, R1-051057, " DownlinkSynchronization Channel Schemes for E-UTRA ", Texas Instruments.(3GPP document, numbering: R1-051057, TI company, " descending synchronous signal channel of EUTRA ")

, method (1) has the synchronous channel structure characteristic of simple, but exists the few shortcoming of cell identification quantity.Method (2) and method (3) exist the computation complexity height, the shortcoming that the synchronization channel symbols expense is big.Therefore, above-mentioned three kinds of methods run into big difficulty in actual applications.

Summary of the invention

The objective of the invention is at computation complexity height in the prior art, the big or few problem of cell identification quantity of synchronization channel symbols expense provides a kind of method of cell identification of the OFDMA of being applied to cellular system.The present invention only needs 1 OFDM symbol as sync channel data in every frame, by loading data on the subcarrier of different mode pattern, distinguish the different big numbers in sub-district, again by the frequency domain differential demodulation sequence on the subcarrier of adjacent loading data, distinguish the different little numbers in sub-district, finally unite the identification sub-district, reach the purpose of the extensive quantity cellular cell of identification, make the present invention keep lower computation complexity simultaneously by the small size sign indicating number of big number in sub-district and sub-district.

The present invention is achieved through the following technical solutions, and specifically comprises the steps:

Step 1: transmitting terminal generates the OFDM synchronization channel symbols that contains big number in sub-district and the little number information in sub-district, on frequency domain, whether the subcarrier that participates in process for cell identification in this synchronization channel symbols by loading data, be divided into two classes: the charge carrier carrier wave must be arranged and the charge carrier carrier wave can be arranged, wherein, the charge carrier carrier wave must be arranged and can have in the charge carrier carrier wave really the subcarrier of loading data be collectively referred to as and enable subcarrier, the sub-district of the big number of different districts has different had charge carrier carrier mode patterns, and the sub-district with the little number of different districts is in the adjacent different frequency domain differential demodulation sequence of loading on the subcarrier of enabling;

Step 2: receiving terminal obtains frame synchronization and carrier frequency synchronization, and extracts synchronization channel symbols according to utilizing prior art, removes Cyclic Prefix, through compensate of frequency deviation, remakes FFT (fast Fourier transform), obtains the frequency domain sequence of synchronization channel symbols;

Step 3: the energy sequence mode pattern of the had charge carrier carrier wave that identification receives, obtain the big number in sub-district, it is the energy sequence of the had charge carrier carrier wave of calculation procedure two gained frequency domain synchronization channel symbols, as the had charge carrier carrier mode pattern of receiving, mode pattern set carrying out match search with the had charge carrier carrier wave of itself and predefined, find pattern, and then identify the big number in sub-district of this pattern representative with maximum correlation;

Step 4: discern the frequency domain differential demodulation sequence that loads on the subcarrier of loading data, obtain the little number in sub-district, promptly earlier by definite the had charge carrier carrier wave pattern of step 3, and known the charge carrier carrier set must be arranged, obtain enabling the sequence number set of adjacent sub-carrier in the subcarrier, then, this sequence number of differential ference spiral is gathered pairing frequency domain synchronization channel sequence, acquisition is used to discern the frequency domain differential demodulation sequence of the little number in sub-district, again by this sequence of identification, reaches the purpose of the little number in identification sub-district.Finally unite the identification sub-district by the small size sign indicating number of big number in sub-district and sub-district.

Can also enter many symbol judgements algorithm behind the completing steps four, promptly investigate a plurality of synchronization channel symbols, use different judgement merging methods and different mode decision schemes, carry out cell identification, thereby obtain than the small size sign indicating number of single judgement big number in more reliable sub-district and sub-district decision value.

Below the invention will be further described:

(1) generates the OFDM synchronization channel symbols that contains big number in sub-district and the little number information in sub-district

OFDM is a kind of multicarrier modulation system, can carry qam symbol or PSK symbol on each subcarrier, and its modulation process can be represented with IDFT (discrete fourier inverse transformation) and DFT (discrete Fourier transform).If N represents the number of OFDM subcarrier, because the symmetry of IDFT and DFT, N represents that also the live part of OFDM symbol counts, and T represents the effective width of OFDM symbol, and subcarrier spacing is f _o=1/T.If the frequency domain data that a (k) expression transmitting terminal loads on k subcarrier of synchronization channel symbols; In b (l) the expression synchronization channel symbols, the base band time domain data of l sampled point.A (k) is made b (l) some IDFT:

$b\left(l\right)=\frac{1}{N}\underset{k=-N_{u1}}{\overset{N_{u2}}{\mathrm{\&Sigma;}}}a\left(k\right)\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20061002598600281.png,A20061002598600301.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{\mathrm{kl}}{N}\right),(l=-N_g,...,\mathrm{0,1},...,N-1)---\left(1\right)$

In the formula, N _U1The number of the available subcarrier of the negative spectral regions of expression base band, N _U2The number of the available subcarrier of the positive spectral regions of expression base band, N _U1+ N _U2=N _uThe total number of expression available subcarrier, N _gBe counting of Cyclic Prefix.

To the mode pattern of different subcarrier loading datas, according to the subcarrier loading data, the set of definition subcarrier sequence number is as follows with the message reflection of the big number in sub-district in consideration:

Available subcarrier S contains (C (S)=N _u) individual element:

S＝{S(i)|1≤i≤C(S)，S(i)＜S(i+1)，-N _u1≤S(i)≤N _u2，S(i)≠0} (2)

Participate in the subcarrier S of process for cell identification _Cell, generally determine that by the related protocol standard is unique it contains C (S _Cell) individual element:

S _cell＝{S _c(i)|1≤i≤C(S _cell)，S _c(i)＜S _c(i+1)，S _c(i)∈S} (3)

S _CellWith the relation of S be: S _Cell S.

Charge carrier carrier wave S must be arranged _Load, contain C (S _Load) individual element:

S _load＝{S _l(i)|1≤i≤C(S _load)，S _l(i)＜S _l(i+1)，S _l(i)∈S _cell} (4)

In the formula (4), S _LoadBelong to system design parameters, it is transparent for transmitting terminal and receiving terminal, and promptly both sides all know S exactly before communication _Load

Charge carrier carrier wave S can be arranged _Option, contain C (S _Option)=C (S _Cell)-C (S _Load) individual element:

S _option＝{S _o(i)|1≤i≤C(S _option)，S _o(i)＜S _o(i+1)，S _o(i)∈S _cell\S _load} (5)

Easily see S _Cell, S _LoadAnd S _OptionRelation be: S _Load∪ S _Option=S _Cell, S _Load∩ S _Option=.

S _OptionIn the sub-district of jack per station g, by different binary sequence d ^g={ d ^g(j) | (B is d to 1≤j≤B} ^gLength, and B=C (S _Option)) act on, form different data load mode patterns, i.e. d ^gIn the S of 0 element institute correspondence position _OptionOn loading data not, the S of 1 element institute correspondence position _OptionOn loading data, with the set form above-mentioned two kinds of information slips are shown S _Null ^gAnd S _Surv ^g:

S _Null ^sAnd S _Surv ^gContaining element number respectively is C (S _Null ^g) and C (S _Surv ^g), i.e. d ^gIn the number of 0 element and 1 element be respectively C (S _Null ^g) and C (S _Surv ^g).Because $S_{\mathrm{null}}^g\&cup;S_{\mathrm{surv}}^g=S_{\mathrm{option}},$ And

So $C\left(S_{\mathrm{null}}^g\right)+C\left(S_{\mathrm{surv}}^g\right)=C\left(S_{\mathrm{option}}\right)=B.$

Choose d ^gFor having the autocorrelative pseudo random sequence of sharp-pointed peak value (as m sequence or the like), d ^gCyclic shift sample d ^g(1≤g≤B) as the data load mode pattern of different had charge carrier carrier waves, different d is adopted in the sub-district of the big number g of different districts ^g

Receiving terminal is by energy sequence and different d to the had charge carrier carrier wave received ^gCarry out relevant search, seek correlation peak, thereby determine the big number g of current area.As seen, by the data load mode pattern of charge carrier carrier wave can be arranged, can distinguish B the big number in sub-district at most.

In addition, d ^gAlso can form, be about to d by a plurality of part cascades ^gBe decomposed into

${\mathrm{<figure-callout\; id="1"\; label="d\; g"\; filenames="A20061002598600301.png,A20061002598600302.png"\; state="\{\{state\}\}">d</figure-callout>}}^{g_{}}=\left\{d^{g_1}\left(j\right)\right|1\&le;j\&le;B_1\},{\mathrm{<figure-callout\; id="2"\; label="d\; g"\; filenames="A20061002598600281.png,A20061002598600301.png"\; state="\{\{state\}\}">d</figure-callout>}}^{g_{}}=\{d^{g_2}\left(j\right)|1\&le;j\&le;B_2\},\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;d^{g_n}=\left\{d^{g_n}\left(j\right)\right|1\&le;j\&le;B_n\},$

Satisfy $d^g=({\mathrm{<figure-callout\; id="1"\; label="d\; g"\; filenames="A20061002598600301.png,A20061002598600302.png"\; state="\{\{state\}\}">d</figure-callout>}}^{g_{}},{\mathrm{<figure-callout\; id="2"\; label="d\; g"\; filenames="A20061002598600281.png,A20061002598600301.png"\; state="\{\{state\}\}">d</figure-callout>}}^{g_{}},...,d^{g_n}),$ B ₁+B ₂+…+B _n＝B。d ^G1, d ^G2..., d ^GnBe divided into and have the autocorrelative pseudo random sequence of sharp-pointed peak value (as m sequence or the like).Like this, d ^G1, d ^G2..., d ^GnVarious combination constitute B altogether ₁* B ₂* ... * B _nIndividual different d ^g

In real system, discernible sub-district large size number of codes C _gAlso be an adjustable parameter, such as, choosing length is the m sequence of B=31, the expression system can discern 31 big numbers in sub-district at most, if only need at present to distinguish 8 big numbers in sub-district, then from 31 d ^gIn choose 8 d ^gData load mode pattern as legal had charge carrier carrier wave gets final product, at this moment, and C _g=8.

In the sub-district of the big number of same cells, use different frequency domain differential demodulation data sequences to distinguish the little number in different sub-districts.The big number in definition sub-district is g (1≤g≤C _g) the sub-district in, it must have charge carrier carrier wave S _LoadWith the subcarrier S that certain loading data in the charge carrier carrier wave can be arranged _Surv ^g, be collectively referred to as and enable subcarrier S _Act ^g:

$S_{\mathrm{act}}^g=\left\{S_a^g\left(i\right)\right|1\&le;i\&le;C\left(S_{\mathrm{act}}^g\right),S_a^g\left(i\right)<S_a^g(i+1),S_a\left(i\right)\&Element;S_{\mathrm{load}}\&cup;S_{\mathrm{surv}}^g\}---\left(8\right)$

Because

So $C\left(S_{\mathrm{act}}^g\right)=C\left(S_{\mathrm{load}}\right)+C\left(S_{\mathrm{surv}}^g\right).$ For each S _Act ^g, search for its adjacent sub-carrier to (S _A1 ^g(i), S _A2 ^g(i)), this subcarrier is to belonging to S set _Adj ^g:

In the formula (9), α is the maximum definition distance of adjacent sub-carrier, usually, is subjected to approximately uniform channel effect in order to guarantee adjacent sub-carrier, generally gets α≤4, promptly when the distance between two subcarriers surpasses 4 subcarrier spacings, thinks that just the two is non-conterminous.S _Adj ^gElement number be C (S _Adj ^g), this is the length in order to the frequency domain differential demodulation data sequence of the little number of distinguishing cell.It is pointed out that under the condition of different g C (S _Adj ^g) may be different, be carried in for the information that guarantees each little number in sub-district on the frequency domain differential demodulation sequence of equal length, S _Adj ^gCarry out brachymemma according to minimum length, so, all S _Adj ^gLength be confirmed as D:

$D=\min \left\{C\left(S_{\mathrm{adj}}^g\right)\right|1\&le;g\&le;C_g\}---\left(10\right)$

And then amendment type (9):

Suppose total C _qIndividual frequency domain differential demodulation sequence p ^q={ p ^q(i) } (1≤q≤C _q, 1≤i≤D) (for example PN sequence or GCL (Generalized chirp-like, broad sense is like pulse) difference sequence or the like) is used for distinguishing C _qThe little number in individual sub-district.The big number in sub-district is g, and the little number in sub-district is that p is chosen in the sub-district of q ^qBe loaded into S _A1 ^g(i) and S _a ^g(i) on the Dui Ying adjacent sub-carrier:

$a\left(S_a^g\left(j\right)\right)=\left\{\begin{array}{cc}a\left(S_{a1}^g\left(g\right)\right)p^q\left(i\right)& S_a^g\left(j\right)=S_{a2}^g\left(i\right),1\&le;i\&le;D\\ \exp \left(\mathrm{j\&theta;}\right)& S_a^g\left(j\right)\&NotEqual;S_{a2}^g\left(i\right),1\&le;i\&le;D\end{array}\right.---\left(12\right)$

In the formula (12), θ is a random phase arbitrarily, and the expression part is enabled the constraint that data on the subcarrier are not subjected to g and q, can be used to improve the PAPR (peak-to-average power ratio) of synchronization channel symbols.

In addition, if d ^gBy d ^G1, d ^G2..., d ^GnForm etc. a plurality of part cascades, then need, and then obtain s by formula (8) to formula (11) to each cascade part calculating formula (7) _A1 ^g(i) and S _A2 ^g(i).

Receiving terminal is by differential ference spiral S _A1 ^g(i) and S _A2 ^g(i) data on the correspondence position, and then with all possible p ^qMake cross-correlation, seek peak value, identify p ^qThereby, determine sub-district small size sign indicating number q.As seen, in order to discern q as much as possible, p ^qLength D should be big as far as possible, consider $D<C\left(S_{\mathrm{act}}^g\right)=C\left(S_{\mathrm{load}}\right)+C\left(S_{\mathrm{surv}}^g\right)\&le;C\left(S_{\mathrm{load}}\right)+C\left(S_{\mathrm{option}}\right)=C\left(S_{\mathrm{cell}}\right),$ Therefore, at C (S _Cell) under certain condition, choose suitable parameters C (S _Load) and C (S _Option), and make C (S _Load)+C (S _Surv ^g) big as far as possible, just can make D become big.(2) frame synchronization and Frequency Synchronization

At present, the frame synchronization of OFDM and Frequency Synchronization are comparatively mature technique.Such as, choose

S _cell＝{S _c(i)|1≤i≤C(S _cell)，S _c(i)＜S _c(i+1)，S _c(i)∈S，S _c(i)＝0(mod L)} (13)

Then S S _CellSubcarrier on loading data not, just can generate the OFDM synchronization channel symbols of separation structures such as L, on time domain, calculate the specific delays auto-correlation of synchronization channel symbols, seek the original position that peak value is determined frame, the phase angle of peaking estimates frequency departure again.Referring to document: T.Keller, L.Piazzo, P.Mandarini, L.Hanzo, " Orthogonal Frequency Division MultiplexSynchronization Techniques for Frequency-Selective Fading Channels. " IEEE Journal on Selected Areas in Communications, VOL.19, NO.6, June2001 page (s): 999-1007.(the selected communication technical field periodical of " the OFDM simultaneous techniques under the frequency selective fading channels " IEEE)

Again such as, S S _CellIn a part of subcarrier on load fixing frequency domain sequence, thereby generate fixing time domain sequences, this time domain sequences all is in advance known for transmitting terminal and receiving terminal, receiving terminal carries out continuous relevant search to the received signal with this time domain sequences, the relevant peaks position is exactly the original position of OFDM symbol, investigate the phase property of receiving sequence then, estimate frequency departure, referring to document: 3GPP, R1-060781, NTT DoCoMo, " Cell Search Time Performance of Three-Step CellSearch Method ".(3GPP document, numbering: R1-060781, NTT DoCoMo company, " three step small region search methods are in the performance of the performance aspect search time ")

If r (m) expression receiving terminal is received the base band time domain data of m sampled point of leading symbol, h (l) expression time-delay is l the pairing time domain channel response in sampling instant path; N (m) expression channel is to the time domain additive Gaussian noise of r (m); ψ is a first phase, f _ΔBe to the frequency deviation after the subcarrier spacing normalization, ε is that then the expression formula of r (m) is to the frame synchronization deviation after the sampled point interval normalization:

$r\left(m\right)=\exp (\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20061002598600281.png,A20061002598600301.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{f}_{\mathrm{\&Delta;}}\frac{(m-\mathrm{\&epsiv;})}{N}+\mathrm{j\&psi;})\underset{l}{\mathrm{\&Sigma;}}b(m-\mathrm{\&epsiv;}-l)h\left(l\right)+n(m-\mathrm{\&epsiv;})---\left(14\right)$

According to the result of frame synchronization and Frequency Synchronization, r (m) is carried out corresponding compensation, and remove Cyclic Prefix:

$\stackrel{\&OverBar;}{r}\left(m\right)=\exp \left(\mathrm{j\&psi;}\right)\underset{l}{\mathrm{\&Sigma;}}b(m-l)h\left(l\right)+\stackrel{\&OverBar;}{n}(m-\mathrm{\&epsiv;}),(m=\mathrm{0,1},...,N-1)---\left(15\right)$

R (m) is made N point DFT, obtains the frequency domain sequence of synchronization channel symbols:

$z\left(k\right)=\underset{m=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\stackrel{\&OverBar;}{r}\left(m\right)\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20061002598600281.png,A20061002598600301.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{\mathrm{mk}}{N}),(-{\mathrm{<figure-callout\; id="1"\; label="N\; u"\; filenames="A20061002598600301.png,A20061002598600302.png"\; state="\{\{state\}\}">N</figure-callout>}}_u\&le;k\&le;N_{u2})---\left(16\right)$

With formula (1) substitution formula (15), substitution formula again (16) obtains its equivalent frequency-domain expression and is:

z(k)＝a(k)H(k)+n′(k)(-N _u1≤k≤N _u2) (17)

In the formula, H (k) is the frequency domain influence of multidiameter fading channel to k subcarrier, and n ' is the frequency domain additive noise of channel to k subcarrier (k).

(3) the energy sequence mode pattern of the had charge carrier carrier wave of identification reception obtains the big number g in sub-district

For { z (k) }, calculate S _OptionThe energy sequence of corresponding subcarrier is with itself and d ^gBe correlated with, as the formula (18):

$R\left(g\right)=\underset{i=1}{\overset{B}{\mathrm{\&Sigma;}}}{\left|z\left(S_o\left(i\right)\right)\right|}^2{d}^g\left(i\right),(1\&le;g\&le;C_g)---\left(18\right)$

Then, with the g of R (g) peak value correspondence judgment value as the big number in sub-district

$\hat{g}=\underset{g}{\arg \max }\left\{R\left(g\right)\right|1\&le;g\&le;C_g\}$

The calculating of this step mainly concentrates on formula (18), calculates | z (S _o(i)) | ²Need C (S _Option) inferior complex multiplication.Because d ^gBe binary sequence, therefore, the sum of products in the formula (18) deteriorates to the real number addition, only needs altogether

Inferior real number addition, equivalence is Inferior complex addition.

(4) discern the frequency domain differential demodulation sequence that loads on the subcarrier of loading data, obtain the g that sub-district small size sign indicating number q obtains according to prime, obtain S by formula (6) and formula (7) _Mull ^gAnd S _Surv ^g, obtain S by formula (8) again _Act ^g, investigate all S according to formula (9) then _Adj ^g, and obtain the length D of frequency domain differential demodulation sequence by formula (10), so, according to formula (11), determine the S set that adjacent sub-carrier is right _Adj ^gWhen not considering noise, when only considering multidiameter fading channel, differential ference spiral S _A1 ^g(i) and S _A2 ^g(i) data on the Dui Ying adjacent sub-carrier are got by formula (12) and formula (17):

$w\left(i\right)=\frac{z\left(S_{a2}^G\left(i\right)\right)}{z\left(S_{a1}^G\left(i\right)\right)}=\frac{z\left(S_{a2}^G\left(i\right)\right)H\left(S_{a2}^G\left(i\right)\right)+n^{\&prime;}\left(S_{a2}^G\left(i\right)\right)}{z\left(S_{a1}^G\left(i\right)\right)H\left(S_{a1}^G\left(i\right)\right)+n^{\&prime;}\left(S_{a1}^G\left(i\right)\right)},(1\&le;i\&le;D)---\left(20\right)$

The condition of consideration formula (9), when α hour, can think $H\left(S_{a2}^G\left(i\right)\right)\&ap;H\left(S_{a1}^G\left(i\right)\right),$ So formula (20) is reduced to:

$w\left(i\right)=\frac{z\left(S_{a2}^G\left(i\right)\right)}{z\left(S_{a1}^G\left(i\right)\right)}=\frac{a\left(S_{a2}^G\left(i\right)\right)}{a\left(S_{a1}^G\left(i\right)\right)}{=p}^q\left(i\right),(1\&le;i\&le;D)---\left(21\right)$

Compute vector w={w (i) } and p ^qRelevant:

$T\left(q\right)=\underset{i=1}{\overset{D}{\mathrm{\&Sigma;}}}{w}^{*}\left(i\right)p^q\left(i\right),(1\&le;q\&le;C_q)---\left(22\right)$

Then, with the q of T (q) peak value correspondence judgment value as the little number in sub-district

$\hat{q}=\underset{q}{\arg \max }\left\{\right|T\left(q\right)\left|\right|1\&le;q\&le;C_q\}---\left(23\right)$

The calculating of this step mainly concentrates on formula (21), formula (22) and formula (23).Formula (21) needs complex multiplication D time, and formula (22) needs D * C _qInferior complex multiplication and (D-1) * C _qCalculate in the inferior complex addition, formula (23) | T (q) | need C _qInferior complex multiplication.

(5) many symbol judgements algorithm

By formula (19) and formula (23) as can be known, the present invention can discern C altogether _gC _qMany symbol judgements algorithm in order to finish the cell identification task more reliably, can be adopted in individual different sub-district, promptly investigate a plurality of synchronization channel symbols, use different mode decision schemes, carry out cell identification, thereby obtain than the small size sign indicating number of single judgement big number in more reliable sub-district and sub-district decision value.

Do not consider time synchronized and the Frequency Synchronization of OFDM, only consider the cell identification problem.

Method one: investigate U synchronization channel symbols,, obtain U the big number estimated value in sub-district according to formula (18) and formula (19) for each synchronization channel symbols

(1≤x≤U), right then

Carry out majority rule and judge, that is:

$\hat{g}=\underset{g}{\arg \max }\left\{\mathrm{count}(\hat{g}\left(x\right),g)\right|1\&le;x\&le;U,1\&le;g\&le;C_g\}---\left(24\right)$

Wherein,

Expression

In equal the element number of g.When

When having plural value, need append and investigate 1 synchronization channel symbols, unique until occurring

If spend the individual synchronization channel symbols of U ' altogether, obtain unique According to To each synchronization channel symbols, calculating formula (21) and formula (22) get T _x(q) (1≤x≤U), square merging T _x(q) afterwards, use formula (25) to obtain the estimated value of the little number in sub-district again

$\hat{q}=\underset{q}{\arg \max }\left\{\underset{x=1}{\overset{U^{\&prime;}}{\mathrm{\&Sigma;}}}{\left|T_x\left(q\right)\right|}^2\right|1\&le;q\&le;C_q\}---\left(25\right)$

Method one needs altogether answers that to take advantage of number of times be U ' * (C (S _Option)+D+D * C _q+ C _q), be added with number of times and be

$U^{\&prime;}\&times;(C\left(S_{\mathrm{surv}}^g\right)\&times;C_g/2+(D-1)\&times;C_q).$

Method two: investigate U synchronization channel symbols,, calculate R according to formula (18) for each synchronization channel symbols _x(g) (1≤x≤U), addition merges R then _x(g):

$R\left(g\right)=\underset{x=1}{\overset{U}{\mathrm{\&Sigma;}}}{R}_x\left(g\right),(1\&le;g\&le;C_g)---\left(26\right)$

Formula (26) equivalence needs (U-1) C _gBe added with for/2 times.Then, obtain according to formula (19)

According to

To each synchronization channel symbols, calculating formula (21) and formula (22) get T _x(q) (1≤x≤U), square merging T _x(q) afterwards, use formula (25) to obtain the estimated value of the little number in sub-district again

Method two needs altogether answers that to take advantage of number of times be U * (C (S _Option)+D+D * C _q+ C _q), being added with number of times is U * (C (S _Surv ^g) * C _g/ 2+ (D-1) * C _qThe C of)+(U-1) _g/ 2.

After having adopted repeatedly decision algorithm, estimated performance of the present invention is significantly improved.

The invention has the advantages that: in every frame, only need 1 OFDM symbol as sync channel data, has the low advantage of sync channel data expense, and the peak-to-average power ratio of this symbol is very low, in addition, adopt the cell recognition method of cascade, earlier by loading data on the subcarrier of different mode pattern, distinguish the different big numbers in sub-district, again by loading different frequency domain differential demodulation sequences on the adjacent subcarrier of loading data, distinguish the different little numbers in sub-district, finally unite the identification sub-district, reach the purpose of the extensive quantity cellular cell of identification, make the present invention keep lower computation complexity simultaneously by the small size sign indicating number of big number in sub-district and sub-district.

Description of drawings

Fig. 1 is an OFDM baseband modulation and demodulation block diagram

Fig. 2 is an enforcement block diagram of the present invention

Fig. 3 is d ^gThe circulation autocorrelation function graph

Fig. 4 is the mode pattern of enabling subcarrier of synchronization channel symbols of sub-district of g=19 and the loading position of frequency domain differential demodulation sequence for the big number in sub-district

Fig. 5 is the typical case figure of R (g)

Fig. 6 is the typical case figure of T (q)

Fig. 7 is the position relation of receiving terminal and 3 adjacent cells

Fig. 8 is under many cell conditions, and the scheme of the present invention and Motorola is used the cell identification accuracy performance map of symbol judgement method more than first kind

Fig. 9 is under many cell conditions, and the scheme of the present invention and Motorola is used the cell identification accuracy performance map of symbol judgement method more than second kind

Embodiment

Provide a concrete OFDM parameter configuration below, set forth performing step of the present invention.Need to prove that the parameter in the following example does not influence generality of the present invention.

The document of 3GPP tissue: TR 25.814 V0.3.1, " Physical Layer Aspects forEvolved UTRA " (physical layer specification that the universal mobile telecommunications system of evolution and continental rise radio insert)

The one group of OFDM parameter that provides is as follows:

System bandwidth 1.92MHz

Sub-carrier number N 128

Effective sub-carrier number N _u75 (get N _U1=38, N _U2=37)

Effective bandwidth 1.25MHz

Subcarrier spacing f _o15kHz

Cyclic Prefix N _g32 points (16.67us)

Symbol period T 128 points (66.67us)

Selection of parameter of the present invention is as follows:

α＝4

S＝{-38，-37，...，-1，1，...，36，37}，C(S)＝75。

S _Cell={ S _c(i) | 1≤i≤C (S _Cell), S _c(i)＜S _c(i+1), S _c(i) ∈ S, S _c(i)=0 (mod 2) }, that is:

S _cell＝{-38，-36，...，-2，2，...，34，36} (27)

C (S then _Cell)=37.S S _CellSubcarrier on loading data not, thereby generate the synchronization channel symbols of 2 five equilibriums.In addition, in formula (4), choose

S _load＝{-38，-36，-34，32，34，36} (28)

So, in the formula (5),

S _option＝{-32，-30，...，-2，2，...，28，30} (29)

C (S is then arranged _Load)=6 and C (S _Option)=31.

It is pointed out that in this example for S _LoadAnd S _OptionChoose and do not influence versatility of the present invention.In actual applications, S _LoadAnd S _OptionAs long as choose and satisfy S _Load∪ S _Option=S _Cell, S _Load∩ S _Option= and S _OptionDo not get final product for empty set.

Performing step of the present invention is as follows:

(1) generates synchronization channel symbols

Because C (S _Option)=31=2 ⁵-1, and the length of m sequence is 2 ^t-1 (t is a positive integer) is so can choose d ^gBe the m sequence of t=5, selecting its primitive polynomial is 1+x ²+ x ⁵, d then ^gThe cyclic shift sample have 31, as follows:

g	d	g
			1	0000101011101100011111001101001
2	0001010111011000111110011010010
		3	0010101110110001111100110100100
4	0101011101100011111001101001000
		5	1010111011000111110011010010000
6	0101110110001111100110100100001

7	1011101100011111001101001000010
		8	0111011000111110011010010000101
9	1110110001111100110100100001010
		10	1101100011111001101001000010101
11	1011000111110011010010000101011
		12	0110001111100110100100001010111
13	1100011111001101001000010101110
		14	1000111110011010010000101011101
15	0001111100110100100001010111011
		16	0011111001101001000010101110110
17	0111110011010010000101011101100
		18	1111100110100100001010111011000
19	1111001101001000010101110110001
		20	1110011010010000101011101100011
21	1100110100100001010111011000111
		22	1001101001000010101110110001111
23	0011010010000101011101100011111
		24	0110100100001010111011000111110
25	1101001000010101110110001111100
		26	1010010000101011101100011111001
27	0100100001010111011000111110011
		28	1001000010101110110001111100110
29	0010000101011101100011111001101
		30	0100001010111011000111110011010
31	1000010101110110001111100110100

It is pointed out that and choose the m sequence in this example as d ^g, do not influence versatility of the present invention.In real system, can choose other sequences as d ^g

So the present invention can discern B=31 the big number in sub-district at most under above-mentioned physical layer condition, any d ^gThe circulation auto-correlation function as shown in Figure 3.The sub-district the discerned large size number of codes of getting system is C _g=B=31.

For different g,, get S according to formula (8) _Act ^g, as follows:

g	S act g
		1	-38 -36 -34 -24 -20 -16 -14 -12 -8 -6 4 6 8 10 12 18 20 24 30 32 34 36
2	-38 -36 -34 -26 -22 -18 -16 -14 -10 -8 2 4 6 8 10 16 18 22 28 32 34 36
		3	-38 -36 -34 -28 -24 -20 -18 -16 -12 -10 -2 2 4 6 8 14 16 20 26 32 34 36
4	-38 -36 -34 -30 -26 -22 -20 -18 -14 -12 -4 -2 2 4 6 12 14 18 24 32 34 36
		5	-38 -36 -34 -32 -28 -24 -22 -20 -16- 14 -6 -4 -2 2 4 10 12 16 22 32 34 36
6	-38 -36 -34 -30 -26 -24 -22 -18 -16 -8 -6 -4 -2 2 8 10 14 20 30 32 34 36
		7	-38 -36 -34 -32 -28 -26 -24 -20 -18 -10 -8 -6 -4 -2 6 8 12 18 28 32 34 36
8	-38 -36 -34 -30 -28 -26 -22 -20 -12 -10 -8 -6 -4 4 6 10 16 26 30 32 34 36
		9	-38 -36 -34 -32 -30 -28 -24 -22 -14- 12 - 10 -8 -6 2 4 8 14 24 28 32 34 36
10	-38 -36 -34 -32 -30 -26 -24 -16 -14 -12 -10 -8 -2 2 6 12 22 26 30 32 34 36
		11	-38 -36 -34 -32 -28 -26 -18 -16 -14 -12 -10 -4 -2 4 10 20 24 28 30 32 34 36
12	-38 -36 -34 -30 -28 -20 -18 -16 -14 -12 -6 -4 2 8 18 22 26 28 30 32 34 36

13	-38 -36 -34 -32 -30 -22 -20 -18 -16 -14 -8 -6 -2 6 16 20 24 26 28 32 34 36
		14	-38 -36 -34 -32 -24 -22 -20 -18 -16 -10 -8 -4 4 14 18 22 24 26 30 32 34 36
15	-38 -36 -34 -26 -24 -22 -20 -18 -12 -10-6 2 12 16 20 22 24 28 30 32 34 36
		16	-38 -36 -34 -28 -26 -24 -22 -20 -14 -12 -8 -2 10 14 18 20 22 26 28 32 34 36
17	-38 -36 -34 -30 -28 -26 -24 -22 -16 -14 -10 -4 8 12 16 18 20 24 26 32 34 36
		18	-38 -36 -34 -32 -30 -28 -26 -24 -18 -16 -12 -6 6 10 14 16 18 22 24 32 34 36
19	-38 -36 -34 -32 -30 -28 -26 -20 -18 -14 -8 4 8 12 14 16 20 22 30 32 34 36
		20	-38 -36 -34 -32 -30 -28 -22 -20 -16 -102 6 10 12 14 18 20 28 30 32 34 36
21	-38 -36 -34 -32 -30 -24 -22 -18 -12 -2 4 8 10 12 16 18 26 28 30 32 34 36
		22	-38 -36 -34 -32 -26 -24 -20 -14 -4 2 6 8 10 14 16 24 26 28 30 32 34 36
23	-38 -36 -34 -28 -26 -22 -16 -6 -2 4 6 8 12 14 22 24 26 28 30 32 34 36
		24	-38 -36 -34 -30 -28 -24 -18 -8 -4 2 4 6 10 12 20 22 24 26 28 32 34 36
25	-38 -36 -34 -32 -30 -26 -20 -10 -6 -2 2 4 8 10 18 20 22 24 26 32 34 36
		26	-38-36-34-32-28-22-12-8 -4 -2 2 6 8 16 18 20 22 24 30 32 34 36
27	-38 -36 -34 -30 -24 -14 -10 -6 -4 -2 4 6 14

	16 18 20 22 28 30 32 34 36
		28	-38 -36 -34 -32 -26 -16 -12 -8 -6 -4 2 4 12 14 16 18 20 26 28 32 34 36
29	-38 -36 -34 -28 -18 -14 -10 -8 -6 -2 2 10 12 14 16 18 24 26 30 32 34 36
		30	-38 -36 -34 -30 -20 -16 -12 -10 -8 -4 -2 8 10 12 14 16 22 24 28 32 34 36
31	-38 -36 -34 -32 -22 -18 -14 -12 -10 -6 -4 6 8 10 12 14 20 22 26 32 34 36

Because d ^gIn contain

So, S _Act ^gContain $C\left(S_{\mathrm{act}}^g\right)=C\left(S_{\mathrm{load}}\right)+C\left(S_{\mathrm{surv}}^g\right)=6+16=22$ Individual element.According to formula (9), under the condition of α=4, for each S _Act ^g, search for its corresponding S _Adj ^g, get D=16 by formula (10), so obtain revised S according to formula (11) _Adj ^g, with S _Adj ^gIn S _A1 ^g(i) and S _A2 ^g(i) it is as follows to make form:

g	S a1 g(i)
		1	-38，-36，-24，-20，-16，-14，-12，-8，4，6，8，10，18，20，30，32
2	-38，-36，-26，-22，-18，-16，-14，-10，2，4，6，8，16，18，28，32
		3	-38，-36，-28，-24，-20，-18，-16，-12，-2，2，4，6，14，16，32，34
4	-38，-36，-34，-30，-26，-22，-20，-18，-14，-4，-2，2，4，12，14，32
		5	-38，-36，-34，-32，-28，-24，-22，-20，-16，-6，-4，-2，2，10，12，32
6	-38，-36，-34，-30，-26，-24，-22，-18，-8，-6，-4，-2，8，10，30，32
		7	-38，-36，-34，-32，-28，-26，-24，-20，-10，-8，-6，-4，6，8，28，32
8	-38，-36，-34，-30，-28，-26，-22，-12，-10，-8，-6，4，6，26，30，32
		9	-38，-36，-34，-32，-30，-28，-24，-14，-12，-10，-8，2，4，24，28，32
10	-38，-36，-34，-32，-30，-26，-16，-14，-12，-10，-2，2，22，26，30，32
		11	-38，-36，-34，-32，-28，-18，-16，-14，-12，-4，20，24，28，30，32，34
12	-38，-36，-34，-30，-20，-18，-16，-14，-6，18，22，26，28，30，32，34
		13	-38，-36，-34，-32，-22，-20，-18，-16，-8，-6，16，20，24，26，28，32

14	-38，-36，-34，-24，-22，-20，-18，-10，-8，14，18，22，24，26，30，32
		15	-38，-36，-26，-24，-22，-20，-12，-10，12，16，20，22，24，28，30，32
16	-38，-36，-28，-26，-24，-22，-14，-12，10，14，18，20，22，26，28，32
		17	-38，-36，-34，-30，-28，-26，-24，-16，-14，8，12，16，18，20，24，32
18	-38，-36，-34，-32，-30，-28，-26，-18，-16，6，10，14，16，18，22，32
		19	-38，-36，-34，-32，-30，-28，-20，-18，4，8，12，14，16，20，30，32
20	-38，-36，-34，-32，-30，-22，-20，2，6，10，12，14，18，28，30，32
		21	-38，-36，-34，-32，-24，-22，4，8，10，12，16，26，28，30，32，34
22	-38，-36，-34，-26，-24，2，6，8，10，14，24，26，28，30，32，34
		23	-38，-36，-28，-26，-6，4，6，8，12，22，24，26，28，30，32，34
24	-38，-36，-34，-30，-28，-8，2，4，6，10，20，22，24，26，28，32
		25	-38，-36，-34，-32，-30，-10，-6，-2，2，4，8，18，20，22，24，32
26	-38，-36，-34，-32，-12，-8，-4，-2，2，6，16，18，20，22，30，32
		27	-38，-36，-34，-14，-10，-6，-4，4，14，16，18，20，28，30，32，34
28	-38，-36，-34，-16，-12，-8，-6，2，12，14，16，18，26，28，32，34
		29	-38，-36，-18，-14，-10，-8，-6，-2，10，12，14，16，24，26，30，32
30	-38，-36，-34，-20，-16，-12，-10，-8，-4，8，10，12，14，22，24，28
		31	-38，-36，-34，-22，-18，-14，-12，-10，-6，6，8，10，12，20，22，32

g	S a2 g(i)
		1	-36，-34，-20，-16，-14，-12，-8，-6，6，8，10，12，20，24，32，34
2	-36，-34，-22，-18，-16，-14，-10，-8，4，6，8，10，18，22，32，34
		3	-36，-34，-24，-20，-18，-16，-12，-10，2，4，6，8，16，20，34，36
4	-36，-34，-30，-26，-22，-20，-18，-14，-12，-2，2，4，6，14，18，34
		5	-36，-34，-32，-28，-24，-22，-20，-16，-14，-4，-2，2，4，12，16，34
6	-36，-34，-30，-26，-24，-22，-18，-16，-6，-4，-2，2，10，14，32，34
		7	-36，-34，-32，-28，-26，-24，-20，-18，-8，-6，-4，-2，8，12，32，34
8	-36，-34，-30，-28，-26，-22，-20，-10，-8，-6，-4，6，10，30，32，34

9	-36，-34，-32，-30，-28，-24，-22，-12，-10，-8，-6，4，8，28，32，34
		10	-36，-34，-32，-30，-26，-24，-14，-12，-10，-8，2，6，26，30，32，34
11	-36，-34，-32，-28，-26，-16，-14，-12，-10，-2，24，28，30，32，34，36
		12	-36，-34，-30，-28，-18，-16，-14，-12，-4，22，26，28，30，32，34，36
13	-36，-34，-32，-30，-20，-18，-16，-14，-6，-2，20，24，26，28，32，34
		14	-36，-34，-32，-22，-20，-18，-16，-8，-4，18，22，24，26，30，32，34
15	-36，-34，-24，-22，-20，-18，-10，-6，16，20，22，24，28，30，32，34
		16	-36，-34，-26，-24，-22，-20，-12，-8，14，18，20，22，26，28，32，34
17	-36，-34，-30，-28，-26，-24，-22，-14，-10，12，16，18，20，24，26，34
		18	-36，-34，-32，-30，-28，-26，-24，-16，-12，10，14，16，18，22，24，34
19	-36，-34，-32，-30，-28，-26，-18，-14，8，12，14，16，20，22，32，34
		20	-36，-34，-32，-30，-28，-20，-16，6，10，12，14，18，20，30，32，34
21	-36，-34，-32，-30，-22，-18，8，10，12，16，18，28，30，32，34，36
		22	-36，-34，-32，-24，-20，6，8，10，14，16，26，28，30，32，34，36
23	-36，-34，-26，-22，-2，6，8，12，14，24，26，28，30，32，34，36
		24	-36，-34，-30，-28，-24，-4，4，6，10，12，22，24，26，28，32，34
25	-36，-34，-32，-30，-26，-6，-2，2，4，8，10，20，22，24，26，34
		26	-36，-34，-32，-28，-8，-4，-2，2，6，8，18，20，22，24，32，34
27	-36，-34，-30，-10，-6，-4，-2，6，16，18，20，22，30，32，34，36
		28	-36，-34，-32，-12，-8，-6，-4，4，14，16，18，20，28，32，34，36
29	-36，-34，-14，-10，-8，-6，-2，2，12，14，16，18，26，30，32，34
		30	-36，-34，-30，-16，-12，-10，-8，-4，-2，10，12，14，16，24，28，32
31	-36，-34，-32，-18，-14，-12，-10，-6，-4，8，10，12，14，22，26，34

Choose p ^qBe the GCL difference sequence, because D=16, so the least prime bigger than D is 17, so:

$p^q\left(i\right)=\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20061002598600281.png,A20061002598600301.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{\mathrm{qi}}{17}),(1\&le;q\&le;C_q,1\&le;i\&le;16)---\left(30\right)$

According to the character of GCL difference sequence, the present invention can distinguish out C by formula (30) _q=16 little numbers in sub-district.So the present invention can discern C altogether _gC _q=31 * 16=496 different districts.

Suppose certain sub-district g=19, q=6 gets according to above table: d ¹⁹={ 1111001101001000010101110110001}

$S_{\mathrm{act}}^{19}=\{-38,-36,-34,-32,-30,-28,-26,-20,-18,-14,-\mathrm{8,4,8,12},\mathrm{14,16,20,22,30,32,34,36}\}$

$S_{a1}^g\left(i\right)=(-38,-36,-34,-32,-30,-28,-20,-\mathrm{18,4,8,12,14,16,20,30,32})$

$S_{a2}^g\left(i\right)=(-36,-34,-32,-30,-28,-26,-18,-\mathrm{14,8,12,14,16,20,22,32,34})$

So, on frequency domain, the S of the synchronization channel symbols of the big number in sub-district of g=19 _Act ¹⁹The mode pattern of subcarrier and the loading position S of frequency domain differential demodulation sequence have been loaded _A1 ^g(i) and S _A2 ^g(i) as shown in Figure 4.

According to formula (12), obtain g=19, the frequency domain data that the sub-district of q=6 should load on synchronization channel symbols is as follows:

12	4	Empty	Empty	Empty	exp(jθ)
						13	8	9	4	8	a(4)p 6(9)＝a(4)exp(-j2π×6×9/17)
14	12	10	8	12	a(8)p 6(10)＝a(8)exp(-j2π×6×10/17)
						15	14	11	12	14	a(12)p 6(11)＝a(12)exp(-j2π×6×11/17)
16	16	12	14	16	a(14)p 6(12)＝a(14)exp(-j2π×6×12/17)
						17	20	13	16	20	a(16)p 6(13)＝a(16)exp(-j2π×6×13/17)
18	22	14	20	22	a(20)p 6(14)＝a(20)exp(-j2π×6×14/17)
						19	30	Empty	Empty	Empty	exp(jθ)
20	32	15	30	32	a(30)p 6(15)＝a(30)exp(-j2π×6×15/17)
						21	34	16	32	34	a(32)p 6(16)＝a(32)exp(-j2π×6×16/17)
22	36	Empty	Empty	Empty	exp(jθ)

In certain was once tested, according to above table, the concrete numerical value of a (k) (38≤k≤37) was as follows:

k	a(k)
		-38	0.97999-0.19902j
-36	-0.7494-0.66212j
		-34	0.84192-0.5396j
-32	0.59014-0.8073j
		-30	-0.92674+0.37571j
-28	-0.45961-0.88812j
		-26	-0.93798-0.34669j
-20	0.99919+0.040249j
		-18	-0.97478-0.22316j
-14	-0.23473-0.97206j
		-8	-0.92785+0.37296j

4	0.24902-0.9685j
		8	-0.75597-0.65461j
12	0.86338+0.50455j
		14	0.29813+0.95453j
16	0.97796-0.20879j
		20	-0.72157+0.69234j
22	-0.92295+0.38493j
		30	0.40976-0.9122j
32	-0.98951-0.14448j
		34	0.71161-0.70258j
36	0.71161-0.70258j
		Other
	0

For the transmitting power that guarantees signal keeps constant, on a (k), will multiply by compensating factor $\sqrt{N_u/C\left(S_{\mathrm{act}}^g\right)}=\sqrt{75/22},$ With string and the modular converter 1, IDFT module 2, parallel serial conversion module 3 of such a (k) by Fig. 1, just can generate the branch OFDM synchronization channel symbols such as 2 that comprise big number information in sub-district and the little number information in sub-district, this synchronization channel symbols is inserted cyclic prefix module 4, insertion synchronization channel symbols module 5, D/A modular converter 6, is sent Filtering Processing module 7 through the module of Fig. 1 then, arrives receiving terminal.

Receiving terminal enters process for cell identification according to Fig. 2.

(2) frame synchronization and Frequency Synchronization

At first, receiving terminal carries out frame synchronization and Frequency Synchronization according to Fig. 2.The data that receive are through the processing module 8 that accepts filter of Fig. 1, A/D modular converter 9, lock unit module 15.Because the synchronization channel symbols that generates has the characteristic of 2 five equilibriums, so calculating the half symbols of synchronization channel symbols on time domain, receiving terminal postpones auto-correlation, seek the original position that peak value is determined frame, the phase angle of peaking estimates frequency departure again.According to the result of frame synchronization and Frequency Synchronization, synchronization channel symbols is carried out corresponding compensation.Receive extraction synchronization channel symbols module 10, removal cyclic prefix module 11, string and modular converter 12, DFT and frequency domain equalization module 13, the parallel serial conversion module 14 of data, obtain as the formula (17) { z (k) } through Fig. 1.Then, receiving terminal begins to carry out cell identification according to Fig. 2.

(3) the big number in identification sub-district

Receiving terminal begins to carry out the identification of the big number in sub-district according to Fig. 2.

According to formula (18), obtain R (g).

With R (25) is example, because d ²⁵=1101001000010101110110001111100} gets according to formula (29) and formula (18):

R(25)＝|z(-32)| ²+|z(-30)| ²+|z(-26)| ²+|z(-20)| ²+|z(-10)| ²+|z(-6)| ²+|z(-2)| ²+|z(2)| ²

+|z(4)| ²+|z(8)| ²+|z(10)| ²+|z(18)| ²+|z(20)| ²+|z(22)| ²+|z(24)| ²+|z(26)| ²

When the big number g=19 in sub-district, under multipath channel condition and 0dB white Gaussian noise situation, the typical case of R (g) as shown in Figure 5.

Try to achieve according to formula (19) again

Aspect computation complexity, this step needs 16 complex multiplications and 248 complex addition.

(4) the little number in identification sub-district

Receiving terminal begins to carry out the identification of the little number in sub-district according to Fig. 2.

If the big number correct judgment in sub-district obtains g=19, and then by formula (8) and formula (11) acquisition S _Act ¹⁹And S _Adj ¹⁹, get T (q) according to formula (21) and formula (22) again.Because the p that chooses ^IBe the GCL sequence, formula (22) can realize efficiently by 17 FFT.Earlier to w ^*(i) afterbody is mended one zero, again it is made 17 FFT:

$T\left(q\right)=\underset{i=1}{\overset{17}{\mathrm{\&Sigma;}}}{w}^{*}\left(i\right)\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20061002598600281.png,A20061002598600301.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{\mathrm{qi}}{17}),(1\&le;q\&le;16)---\left(31\right)$

When the little number in sub-district was q=6, under multipath channel condition and 0dB white Gaussian noise situation, the typical case of T (q) as shown in Figure 6.

Obtain according to formula (23) again

Aspect computation complexity, FFT is auxiliary to be calculated owing to introduce, and this step computing cost reduces greatly, only needs 1 17 FFT computing and 32 complex multiplications.

At last, receiving terminal will according to Fig. 2 With Combination as final cell identification result.

(5) repeatedly judgement

Method one: investigate U synchronization channel symbols,, obtain U the big number estimated value in sub-district according to formula (18) and formula (19) for each synchronization channel symbols

(1≤x≤U), according to formula (24) the big number in sub-district is made an estimate then

Use formula (25) to obtain the estimated value of the little number in sub-district again

With Combination be the result of cell identification.

Method two: investigate U synchronization channel symbols,, calculate R according to formula (18) for each synchronization channel symbols _x(g) (1≤x≤U), merge R according to formula (26) again _x(g), according to formula (19) the big number in sub-district is made an estimate then

Use formula (25) to obtain the estimated value of the little number in sub-district again With

Combination be the result of cell identification.

Simulated channel is 6-ray GSM Typical Urban Channel (global mobile communication typical urban zone 6 footpath channels is called for short 6-ray TU), and its parameter is as follows:

	Postpone (us)	Relative power (dB)
			Path 1	0	-3
Path 2	0.2	0
			Path 3	0.5	-2
Path 4	1.6	-6
			Path 5	2.3	-8
Path 6	5.0	-10

Suppose that frequency deviation is-0.6.

When many cell environments of simulation, consider worst situation, be receiving terminal be positioned at the equidistant position of 3 adjacent cells on, as shown in Figure 7, and after thinking that synchronous channel signal sends from 3 sub-districts,, arrive receiving terminal simultaneously through behind the different 6-ray TU, wherein, the g of 3 sub-districts and q are all inequality.The received power of certain sub-district in 3 sub-districts (the big number in sub-district is G, and the little number in sub-district is Q) is the strongest, and this is that target inserts the sub-district, and the received power of two other sub-district is identical, regards it as the signal of interfered cell.Objective definition insert the signal received power of sub-district and two interfered cells the signal received power and ratio be SIR (signal interference ratio), the white Gaussian noise that superposes again on this basis, the signal received power that the power of white Gaussian noise is gone into the sub-district with respect to tag splice is 0dB.Through after the identifying of the present invention, when $\hat{g}=G$ And $\hat{q}=Q$ The time, think that just cell identification is correct.

Think during emulation and obtained right-on frame synchronization and Frequency Synchronization.

In emulation, the performance of having investigated the scheme of the present invention and Motorola compares.The scheme of Motorola is referring to document: 3GPP, R1-051329, " Cell Search and Initial Acquisition for OFDMDownlink ", Motorola.(3GPP document, numbering: R1-051329, motorola inc, " Cell searching of OFDM down link and initial synchronisation ") this scheme is under above-mentioned physical layer condition, can only discern 36 different sub-districts, its quantity only is of the present invention 7.25% (36/496).In addition, the scheme of Motorola also can adopt method one (after repeatedly estimating, judging with majority rule) and method two (judgment variables remakes estimation after merging) to implement.Aspect computation complexity, the scheme of Motorola is whenever by a synchronization channel symbols identification sub-district, needs are answered riding in differential ference spiral 36 times, again with 1 37 FFT computing identification frequency domain sequence, need at last 36 times multiple riding in asking modular arithmetic, therefore, it needs 1 37 FFT computing altogether and takes advantage of again for 72 times, and the present invention needs 1 17 FFT computing, 48 complex multiplications and 248 complex addition altogether whenever by a synchronization channel symbols identification sub-district.Both computation complexities are suitable, all belong to the cell recognition method of low complex degree.

Fig. 8 is under many cell conditions, and the scheme of the present invention and Motorola is used the cell identification accuracy performance map of symbol judgement method more than first kind.This figure has investigated U=5,7,9,11 o'clock situation, simulation curve shows, though the present invention quantitatively is far superior to the scheme of Motorola in cell identification, it is at SIR (SIR＜0dB) hour, need signal interference ratio about 0.6dB than the scheme of Motorola more, just can reach identical estimated performance.Consider the present invention in the quantitative vast improvement of cell identification, its a small amount of cost of paying aspect signal interference ratio is worth.

Fig. 9 is under many cell conditions, and the scheme of the present invention and Motorola is used the cell identification accuracy performance map of symbol judgement method more than second kind.This figure has investigated U=5,7,9,11 o'clock situation, simulation curve shows, though the present invention quantitatively is far superior to the scheme of Motorola in cell identification, it is at SIR (SIR＜0dB) hour, need signal interference ratio about 0.5dB than the scheme of Motorola more, just can reach identical estimated performance.Consider the present invention in the quantitative vast improvement of cell identification, its a small amount of cost of paying aspect signal interference ratio is worth.

Simulation result shows that it is big that the present invention has the identification number of cells, and computation complexity is lower, and the lower advantage of estimated error rate, has very high using value in ofdm system.

Above-mentioned embodiment of the present invention just is used to set forth the example of technology contents of the present invention.The present invention is not limited to above-mentioned embodiment, should not carry out the explanation of narrow sense to it.In the scope of spirit of the present invention and claim, can carry out various changes and implement it.

Claims (5)

1, a kind of method that is applied to the cell identification of OFDMA cellular system is characterized in that, comprises the steps:

Step 1: transmitting terminal generates the OFDM synchronization channel symbols that contains big number in sub-district and the little number information in sub-district, corresponding with the big number in each sub-district is the mode pattern that loading data on the charge carrier carrier wave can be arranged, and corresponding with the small size sign indicating number in each sub-district is to load the frequency domain differential demodulation sequence on the subcarrier in adjacent enabling;

Step 2: receiving terminal obtains frame synchronization and carrier frequency synchronization, and extracts synchronization channel symbols, removes Cyclic Prefix, through compensate of frequency deviation, remakes FFT, obtains the frequency domain sequence of synchronization channel symbols;

Step 3: the energy sequence mode pattern of the had charge carrier carrier wave that identification receives obtains the big number in sub-district;

Step 4: the difference frequency domain sequence that loads on the subcarrier is enabled in identification, obtains the little number in sub-district.

2, the method that is applied to the cell identification of OFDMA cellular system according to claim 1, it is characterized in that, described step 3, calculate the energy sequence of the had charge carrier carrier wave of frequency domain synchronization channel symbols, as the had charge carrier carrier mode pattern of receiving, match search is carried out in the mode pattern set of the had charge carrier carrier wave of itself and predefined, find pattern, and then identify the big number in sub-district of this pattern representative with maximum correlation.

3, the method that is applied to the cell identification of OFDMA cellular system according to claim 1, it is characterized in that, described step 4, the sequence number set of adjacent sub-carrier in the subcarrier is enabled in acquisition, then, this sequence number of differential ference spiral is gathered pairing frequency domain synchronization channel sequence, obtains to be used to discern the frequency domain differential demodulation sequence of the little number in sub-district, by this sequence of identification, reach the purpose of the little number in identification sub-district again.

4, according to claim 1 or the 4 described methods that are applied to the cell identification of OFDMA cellular system, it is characterized in that, after described step 4, enter many symbol judgements algorithm, promptly investigate a plurality of synchronization channel symbols, for each synchronization channel symbols, obtain the big number estimated value in a plurality of sub-districts according to step 3, then it being carried out majority rule judges, after obtaining comparatively reliably the big number estimated value in sub-district, after sub-district in a step 4 small size sign indicating number judgment variables carried out square merging, the littler number in sub-district is made an estimate.

5, according to claim 1 or the 4 described methods that are applied to the cell identification of OFDMA cellular system, it is characterized in that, after described step 4, enter many symbol judgements algorithm, promptly investigate a plurality of synchronization channel symbols, earlier the big number judgment variables in the sub-district in a plurality of synchronization channel symbols is carried out addition and merge, and then the big number in sub-district made comparatively reliably estimate, then, the small size sign indicating number judgment variables of the sub-district in the step 4 carried out square merging after, the littler number in sub-district is made an estimate.

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