CN101166166A - Pilot channel estimating system and estimating method for uplink multi-user code domain - Google Patents

Abstract

The receiver includes the receiving antenna, the frame decomposition module (FDM), DFT-S OFDM demodulation module, and channel estimation disturbance elimination module (CEDEM). The receiving antenna is in use for receiving time domain radio signal of pilot signal with orthogonal code domain. FDM carries out decomposing sub frame for received signal in time domain so as to obtain time domain pilot signal with orthogonal code domain separated out from sub frame signal. DFT-S OFDM demodulation module demodulates the received time domain pilot signal. The demodulated pilot signal is sent to CEDEM. Removing out multi-user disturbance and multipath disturbance, CEDEM outputs user channel response in time domain or in frequency domain. The invention also discloses the system for estimating channel of pilot signal in up going multi-user code domain.

Description

Uplink multi-user code field pilot channel estimating system and method for estimation

Technical field

The present invention relates to a kind of data communication technology, specifically, relate to the uplink multi-user code field pilot channel estimating system and the method for estimation of DFT-SOFDM system among a kind of 3GPP LTE.

Background technology

In radio communication, be vital to obtaining of channel information, the wireless communication system of the practical application channel estimation technique that will adopt certain form without exception almost.Adaptive channel equalizer utilizes channel information to resist the influence of ISI; Diversity technique is utilized channel estimating, realizes the receiver with receive channel signal optimum Match; Maximum Likelihood Detection makes the receiving terminal mistake minimize by channel estimating.The another one important benefit of channel estimating is that it makes correlation demodulation become possibility.Therefore the channel estimating important ring that in any one wireless communication system, all is absolutely necessary.

Channel estimating is divided into blind Channel Estimation and pilot channel estimation.Because the blind Channel Estimation complexity is high and systematic function is lost, and remains the preferred practical plan of current most systems based on the non-blind Channel Estimation of pilot tone.The long speed that can influence communication of the pilot data that inserts too shortly can not effectively estimate channel parameter again, so the optimal design of pilot tone just seems most important.

The design of channel estimating mainly contains two problems: the one, and the selection of pilot frequency information, because the time variation of wireless channel needs receiver constantly channel to be followed the tracks of, so pilot signal also must constantly transmit; The 2nd, existing lower complexity has the design of the channel estimator of good pilot tracking capability again.

Future mobile communications is to the requirement of up link: as support scalable bandwidth, and moderate PAPR/CM guarantees the orthogonality of uplink etc.Under these required, single carrier transmission scheme SC-FDMA had lower PAPR, can improve the validity of power and increase coverage, became to obtain numerous supports, the most promising technology in the current uplink scheme.SC-FDMA can be divided into the IFDMA of time domain generation and the DFT-SOFDM that frequency domain generates according to the difference of the method for signal generation.Because up DFT-S OFDM technology and descending OFDM scheme have similar structure, so up-downgoing can shared a lot of parameters, so DFT-S OFDM becomes physical-layer techniques the most promising in the uplink.

In the DFT-S ofdm system, the design of pilot tone and corresponding channel estimation scheme mainly comprise based on the pilot design scheme of frequency domain quadrature with based on the pilot design scheme of sign indicating number territory quadrature.Frequency domain orthogonal guide frequency scheme is that multi-user's pilot frequency sequence frequency division multiplexing and multiplex mode is identical with data block, different user subcarrier quadrature on frequency domain.Sign indicating number territory orthogonal guide frequency scheme is meant the pilot frequency sequence that utilizes the pilot frequency sequence orthogonality to distinguish different user, and carries out channel estimating according to this, and the different user subcarrier is quadrature on the sign indicating number territory.The orthogonality of sign indicating number sequence not only makes the pilot tone of different user distinguish mutually, and makes it present the trend of white noiseization, has reduced interference each other.Enough satisfy in code length under the prerequisite of demand of the number of users that same subframe dispatches simultaneously, a sign indicating number sequence can adopt any orthogonal code, as orthogonal codes such as CAZAC sign indicating number, PN sign indicating number, OVSF, Hadamard.

In the frequency domain orthogonal guide frequency scheme, because the complete quadrature of pilot tone between the different user of same sub-district, so the number of users in same sub-district is more for a long time, performance is better relatively, but more serious in the co-channel interference of cell edge.

Summary of the invention

The technical problem that this aspect solved provides a kind of uplink multi-user code field pilot channel estimating system, can finish the complete estimation to single user and multi-user's channel impulse response.

Technical scheme is as follows:

Uplink multi-user code field pilot channel estimating system comprises transmitting antenna and reception antenna, also comprises:

The training sequence maker is used to generate the pilot frequency sequence that M is ordered, and the pilot frequency sequence that M is ordered is sent into DFT-S OFDM modulation module then;

DFT-S OFDM modulation module is modulated the pilot frequency sequence that the M that receives is ordered, and the pilot signal after the modulation is sent to into frame module;

Become frame module, receive the pilot frequency sequence after DFT-S OFDM modulation module is modulated,, export described transmitting antenna to and send the synthetic subframe of the pilot group after the modulation;

Reception antenna receives the time domain wireless signal that contains yard pilot signal of territory quadrature of described transmitting antenna;

The frame decomposing module, the time-domain signal that reception antenna is received carries out the subframe decomposition, the time-domain pilot signal of the sign indicating number territory quadrature that obtains separating from the subframe signal;

DFT-S OFDM demodulation module carries out demodulation to the time-domain pilot signal that receives, and the pilot signal after the demodulation sends to the channel estimating interference cancellation module;

The channel estimating interference cancellation module is removed multi-user interference and multipath and is disturbed, output user's time domain or domain channel response.

Another technical problem solved by the invention provides a kind of transmitter of pilot signal of transmitting code field orthogonal, can finish the complete estimation to single user and multi-user's channel impulse response.

Technical scheme is as follows:

The transmitter of the pilot signal of transmitting code field orthogonal comprises transmitting antenna, also comprises:

The training sequence maker is used to generate the pilot frequency sequence that M is ordered, and the pilot frequency sequence that M is ordered is sent into DFT-S OFDM modulation module then;

DFT-S OFDM modulation module is modulated the pilot frequency sequence that the M that receives is ordered, and the pilot signal after the modulation is sent to into frame module;

Become frame module, receive the pilot frequency sequence after DFT-S OFDM modulation module is modulated,, export described transmitting antenna to and transmit the synthetic subframe of the pilot group after the modulation.

Preferably, described DFT-S OFDM modulation module comprises M point modular converter, subcarrier mapping block and N point IFFT module; Wherein,

M point modular converter is used for converting time domain sequences to frequency domain sequence;

The subcarrier mapping block is used to finish the mapping of the subcarrier that M point subcarrier in the frequency domain orders to N;

N point IFFT module is used for frequency domain training sequence is converted to time-domain training sequence.

Another technical problem solved by the invention provides a kind of receiver of pilot signal of receiving code field orthogonal, can improve the anti-interference of channel estimating.

Technical scheme is as follows:

The receiver of the pilot signal of receiving code field orthogonal comprises reception antenna, also comprises frame decomposing module, DFT-S OFDM demodulation module, channel estimating interference cancellation module; Wherein,

Reception antenna receives the time domain wireless signal that contains yard pilot signal of territory quadrature;

The frame decomposing module, the time-domain signal that reception antenna is received carries out the subframe decomposition, the time-domain pilot signal of the sign indicating number territory quadrature that obtains separating from the subframe signal;

DFT-S OFDM demodulation module carries out demodulation to the time-domain pilot signal that receives, and the pilot signal after the demodulation sends to the channel estimating interference cancellation module;

The channel estimating interference cancellation module is removed multi-user interference and multipath and is disturbed, output user's time domain or domain channel response.

Preferably, described DFT-S OFDM demodulation module comprises N point FFT module, subcarrier inverse mapping module and M point IDFT module; Wherein,

N point FFT module is converted to frequency-region signal with time-domain signal, sends to subcarrier inverse mapping module;

Subcarrier inverse mapping module is carried out the inverse mapping of the subcarrier that N point subcarrier orders to M, and the frequency domain despreading of finishing is to received signal handled, and extracts the frequency domain information on the receiving sequence, sends to M point IDFT module;

M point IDFT module is carried out M point IDFT conversion, obtains time domain sequences signal and transmission.

Another technical problem solved by the invention provides a kind of method of pilot signal of transmitting code field orthogonal, can finish the complete estimation to single user and multi-user's channel impulse response.

Technical scheme is as follows:

The method of the pilot signal of transmitting code field orthogonal comprises the steps:

(1) generates the orthogonal pilot frequency sequence that M is ordered;

(2) orthogonal pilot frequency sequence is carried out DFT-S OFDM modulation;

(3) pilot signal after the emission framing.

The pilot signal that another technical problem solved by the invention provides a kind of receiving code field orthogonal is carried out the method for channel estimating, can improve the interference free performance of channel estimating.

Technical scheme is as follows:

The method that the pilot signal of receiving code field orthogonal is carried out channel estimating comprises the steps:

(1) reception contains yard time-domain signal of the pilot signal of territory quadrature;

(2) time-domain signal is carried out subframe and decompose, obtain yard time-domain pilot signal of territory quadrature;

(3) carry out DFT-S OFDM demodulation;

(4) remove multi-user interference and multipath and disturb, output user's time domain or domain channel response.

Another technical problem solved by the invention provides a kind of receiver of pilot signal of receiving code field orthogonal of simplification, can finish the complete estimation to single user and multi-user's channel impulse response.

Technical scheme is as follows:

The receiver of the pilot signal of the receiving code field orthogonal of simplifying comprises reception antenna, is used to receive and contains yard wireless signal of the pilot signal of territory quadrature, also comprises the frame decomposition and goes CP module, simplification channel estimating interference cancellation module; Wherein,

Frame decomposing module and go the CP module, the time-domain signal that described reception antenna is received are carried out subframe and are decomposed and remove CP, and the time-domain pilot signal of the sign indicating number territory quadrature that obtains separating from the subframe signal sends to the channel estimating interference cancellation module;

Simplify the channel estimating interference cancellation module, remove multi-user interference and multipath and disturb, output user's time domain or domain channel response.

Preferably, described simplification channel estimating interference cancellation module comprises:

M point target user CAZAC sequence generator is used to generate the CAZAC sequence that M is ordered, and sends to circular shift module;

Circular shift module to the CAZAC sequence cyclic shift of M dot generation, sends to M point DFT conversion module;

M point DFT conversion module carries out the DFT conversion to the CAZAC sequence after the displacement, sends to M to N subcarrier mapping block;

M is to N subcarrier mapping block, carries out the mapping of the subcarrier that M point subcarrier orders to N, and the frequency domain despreading of finishing is to received signal handled, and extracts the frequency domain information on the receiving sequence, sends to N point IFFT module;

N point IFFT module is converted to time domain sequences with frequency domain sequence, constitutes the DFT-S OFDM time-domain signal of CAZAC orthogonal pilot frequency sequence, and sends to the inner product summation module;

The inner product summation module, to carry out inner product relevant with the DFT-S OFDM time-domain signal that receives, and obtains time domain channel and estimate response.

The pilot signal that another technical problem solved by the invention provides a kind of receiving code field orthogonal of simplification is carried out the method for channel estimating, can improve the interference free performance of channel estimating.

Technical scheme is as follows;

The method that the pilot signal of the receiving code field orthogonal of simplifying is carried out channel estimating comprises the steps:

(1) reception contains yard time-domain signal of the pilot signal of territory quadrature;

(2) time-domain signal is carried out the subframe operation splitting and removes CP, obtain yard time-domain pilot signal of territory quadrature;

(3) remove multi-user interference and multipath and disturb, output user's time domain or domain channel response.

Sign indicating number territory orthogonal guide frequency scheme adopts CAZAC sequence not of the same clan in different sub-districts, compares with frequency domain orthogonal guide frequency scheme, can reduce the co-channel interference of potential interference, the especially cell edge of minizone greatly.In addition, sign indicating number territory orthogonal guide frequency scheme is compared with frequency domain orthogonal guide frequency scheme, because each user's pilot energy all will be distributed on all subcarriers of channel, therefore can estimate the impulse response of whole frequency domain channel, not only can obtain frequency diversity gain and spreading gain, can also be used in combination easily based on the frequency domain dispatching of CQI (Channel Quality Indicator) with based on numerous technology such as SFBC/STBC of many antennas.

Technical solution of the present invention can be finished the complete estimation to the channel impulse response of single user and multi-user's number, is beneficial to carry out to received signal in signal detector balanced and or in the scheduling of channel quality.Simultaneously, can also improve the interference free performance and the complexity performance of channel estimating.

Description of drawings

Fig. 1-A is the code field pilot channel estimating system block diagram of single user system;

Fig. 1-B is the code field pilot channel estimating system block diagram of multi-user system;

Fig. 2 is the subframe structure block diagram of DFT-S ofdm system;

Fig. 3 is a CAZAC cyclic shift schematic diagram;

Fig. 4 is the structured flowchart of CAZAC pilot frequency sequence maker;

Fig. 5 is the structured flowchart of DFT-S OFDM modulation module;

Fig. 6 is the structured flowchart of DFT-S OFDM demodulation module;

Fig. 7-A is the disposed of in its entirety block diagram of interference eliminated;

Fig. 7-B multi-user interference is eliminated theory diagram;

Fig. 7-C multipath interference eliminated block diagram;

Fig. 8 is the structured flowchart of channel estimating interference cancellation module;

Fig. 9 is the structured flowchart of the channel estimating interference cancellation receiver of simplification;

Figure 10 is the structured flowchart of channel estimating interference cancellation module in the receiver of simplifying.

Embodiment

With reference to the accompanying drawings, the preferred embodiments of the present invention are described in detail.

Fig. 1-A is the code field pilot channel estimating system block diagram of single user system; Fig. 1-B is the code field pilot channel estimating system block diagram of multi-user system.

Shown in Fig. 1-A and Fig. 1-B, the first half is the transmitter of the pilot signal of transmitting code field orthogonal, and the latter half is the receiver of the pilot signal of receiving code field orthogonal.

Fig. 2 is the subframe structure block diagram of DFT-S ofdm system.

As shown in Figure 2, in the DFT-S ofdm system, a complete frame structure comprises the subframe of 20 0.5ms, each subframe is made up of 6 Long Block and 2 Short Block, wherein, ShortBlock is used for transmission of reference signals, and Long Block is used for transmitting user data.

The transmitter of the pilot signal of transmitting code field orthogonal comprises training sequence maker, DFT-S OFDM modulation module, becomes frame module, transmitting antenna.

The training sequence maker at first generates the pilot frequency sequence that M is ordered, and the pilot frequency sequence that M is ordered is sent into DFT-S OFDM modulation module and modulated then, and the pilot tone after the modulation send the framing module combinations to become a subframe, exports transmitting antenna to and transmits.

The receiver of the pilot signal of receiving code field orthogonal comprises frame decomposing module, DFT-S OFDM demodulation module, channel estimating interference cancellation module.

Reception antenna receives the time domain wireless signal that contains yard pilot signal of territory quadrature, the frame decomposing module is at first carried out the subframe operation splitting to the time-domain signal that reception antenna receives, the time-domain pilot signal of the sign indicating number territory quadrature that obtains from the subframe signal, separating, by DFT-S OFDM demodulation module it is carried out demodulation DFT-S OFDM then, pilot signal after the demodulation removes multi-user interference by the channel estimating interference cancellation module and multipath disturbs, output user's time domain or domain channel response.

The rudimentary algorithm of receiving terminal estimation multipath channel is considered single user situation.The pilot signal of unique user can be expressed as at receiving terminal through behind the multipath transmisstion:

r＝s ₁h ₁+s ₂h ₂+…+s _ph _p

Wherein, r represents received signal sequence, s _jBe the corresponding circulation CAZAC sequence of each multipath equivalence, h _jBe the channel time domain impulse response of each multipath correspondence, p represents multipath number.

To equation two ends while premultiplication s _j ^*(s _jConjugate transpose), be zero characteristic according to the circulation autocorrelation of CAZAC sequence.

$s_j^{*}r=s_j^{*}{s}_1{h}_1+s_j^{*}{s}_2{h}_2+\·\·\·+s_j^{*}{s}_p{h}_p={\left|s_j\right|}^2{h}_j$

So, can obtain each impulse response directly of time domain channel ${\stackrel{\‾}{h}}_j=\frac{s_j^{*}r}{{\left|s_j\right|}^2}$

According to the time domain impulse response and the corresponding time-delay thereof of each bar multipath, it is made the frequency domain response that Fourier transform can obtain multipath channel.

Consider multi-user's situation, a plurality of users' transmission information can be expressed as r=s at receiving terminal after by multipath transmisstion _1,1h _1,1+ s _1,2h _1,2+ ... + s _{1, p}h _{1, p}+ ... + s _{I, 1}h _{I, 1}+ s _{I, 2}h _{I, 2}+ ... + s _{I, p}h _{I, p}+

Wherein, first i of following target represents the different user numbering.Similar with single user code territory orthogonal pilot channels estimation scheme, equation two ends premultiplication s _{I, j} ^*(s _{I, j}The Hermitian transposition), be again zero characteristic according to the circulation autocorrelation of CAZAC sequence, and the low their cross correlation of CAZAC sequence not of the same clan, can obtain the impulse response in each footpath of time domain channel ${\stackrel{\‾}{h}}_{i,j}\≈\frac{s_{i,j}^{*}r}{{\left|s_{i,j}\right|}^2}.$

As shown in Figure 3, the training sequence maker generates the CAZAC pilot frequency sequence that M is ordered, and the create-rule of this CAZAC sequence is as follows:

1, the user of different districts uses CAZAC pilot frequency sequence not of the same clan.

Has good accurate orthogonality between CAZAC sequence not of the same clan, in order to minimize the interference among multiple users that belongs to different districts.

2, the user in the same sub-district uses CAZAC pilot frequency sequence of the same clan as far as possible.

The CAZAC sequence has desirable circulation autocorrelation, in order to minimize the interference between different user in the single subdistrict.

3, when the multi-user's number in the same sub-district during, can consider to use CAZAC pilot frequency sequence not of the same clan greater than CAZAC number of pilot sequences of the same clan.

Length is N _GThe generation expression formula of CAZAC sequence as follows:

S _u＝(α _u(0)b，α _u(1)b，...，α _u(N _G-1)b)

Wherein, b is that amplitude is 1 multiple scalar factor.Simultaneously

$a_u\left(k\right)=\exp (-j2\mathrm{\πu}\frac{k(k+1)/2+\mathrm{qk}}{N_G})$

Wherein, u=1 ..., N _GThe-1st, family's sequence number of CAZAC sequence, k=0,1 ... N _G-1, q is an arbitrary integer.

CAZAC sequence not of the same clan can embody by the different sequence number u of family, can see, because the value of u is a lot, so this system can support a lot of sub-districts.

With reference to shown in Figure 4, the cyclic shift process is described in detail.For the CAZAC sequence with gang, the multi-user's number that can support is limited.Maximum number of user $N_{\mathrm{UE}\max }=\left[\frac{N_G}{\mathrm{CP}\×\frac{m}{n}}\right].$ Wherein, m=N _G=M, n=N, under the 5M bandwidth condition, M=151, N=256, CP=31 can get N _UEmax=8.Calculate if take 50 subcarriers, support 6 users altogether according to every user's data information, therefore, can be with the every cyclic shift of original M position CAZAC sequence

Be dispensed to a user behind the position, as the pilot tone training sequence.

Because the CAZAC sequence is to the specific (special) requirements of sequence length, M need get prime number just can guarantee good orthogonality.Therefore, when regulation pilot tone among the Short Block takies sub-carrier number and is non-prime number, the nearest prime number of desirable distance regulation sub-carrier number in the reality.But the concrete value table of comparisons one, for example, under the 5M bandwidth condition, to take sub-carrier number be 150 points to the regulation pilot tone among the Short Block, actual desirable M=151.

Table one is the actual carrier number that takies among the SB

Bandwidth	1.25MHz	2.5MH z	5MHz	10MH z	15MH z	20MH z
							IFFT size, (N)	64	128	256	512	768	1024
Regulation takies sub-carrier number	37	75	150	300	450	600
							The actual sub-carrier number (M) that takies	37	73	151	293	449	601

As shown in Figure 5, the internal structure and the processing method of DFT-S OFDM modulation module have been disclosed.After generating the pilot tone training sequence, at first, to doing M point DFT or FFT conversion, time domain sequences is converted to frequency domain by M point modular converter.Then, finish the subcarrier mapping that M point subcarrier is ordered to N in the frequency domain to N subcarrier mapping block, come down to the spread spectrum on the frequency domain by M.Concrete grammar can adopt the centralized mapping method, promptly to the terminal null value of inserting of M point sequence signal, obtains the spread-spectrum signal that N is ordered.

$B_i\left(k\right)=\left\{\begin{array}{ccc}{a}_i\left(k\right)& \mathrm{if}& 0<k\&le;M\\ 0& \mathrm{if}& M<k\&le;N\end{array}\right.$

After finishing frequency domain spread spectrum, need do the conversion of frequency domain-time domain, promptly, frequency domain training sequence is converted to time-domain training sequence by N point IFFT module to frequency-region signal.

Add Cyclic Prefix and form a Short Block before time-domain training sequence, the effective information of guard signal is eliminated intersymbol interference.Cyclic Prefix is duplicating of training sequence tail portion, is attached to the training sequence front end, and length is equal to or greater than the maximum delay of channel, though signal by the time channel that looses, also can guarantee the orthogonality between subchannel, avoid intersymbol interference (ISI).Here getting circulating prefix-length is 31 points.

Under multi-user's situation, be 6 such as number of users, be τ each user's relative time delay ₁, τ ₂..., τ ₆, be without loss of generality, make and satisfy 0 ≡ τ its relative time delay ₁=min{ τ ₁, τ ₂..., τ ₆}≤τ ₂≤ ... ≤ τ ₆≡ max{ τ ₁, τ ₂..., τ ₆.

If

Wherein

The nearest integer of distance alpha between expression zero and the real number α.For user i, establishing its multipath channel memory span is L _i(with chip period T _cBe the interval).It is L that time domain pilot training sequence behind the spread spectrum is added length _gCyclic Prefix, L wherein _gSatisfy L _g〉=max{ α ₁, α ₂..., α ₆}+max{L _i}-1, the Short Block pilot signal that obtains adding behind the Cyclic Prefix is si (k), that is:

$s_i\left(k\right)=\left\{\begin{array}{ccc}{b}_i(k+N-L_g)& \mathrm{if}& 0<k\&le;L_g\\ b_i(k-L_g)& \mathrm{if}& L_g<k\&le;M_g\end{array}\right.$

Wherein, M _g=L _g+ N.Here establish L _gLess than N.

S _i(k) be the pilot signal that ShortBlock sends in subframe of user i.

Becoming the effect of frame module is that 2 Short Block and 6 Long Block that will generate according to defined frame structure are combined into a subframe, export transmitting antenna to and transmit.The frame decomposing module is at first carried out the subframe operation splitting to the time-domain signal that reception antenna receives, and obtains the ShortBlock that separates from the subframe signal.

As shown in Figure 6, describe the internal structure and the processing method of DFT-S OFDM demodulation module, at first a Short Block has been gone circulation prefix processing.

c(k-L _g)＝r(k) L _g＜k≤M _g

Wherein, L _gFor circulating prefix-length and less than N, M _g=L _g+ N.

By N point FFT module time-domain signal is converted to frequency-region signal, obtains C (k), k=1 ..., N.

Do the subcarrier inverse mapping that N point subcarrier is ordered to M through the subcarrier mapping block, the frequency domain despreading of finishing is to received signal handled, and the effective frequency domain information on the receiving sequence is extracted out.Concrete grammar can adopt centralized approach, is about to N point sequence signal end and gives up near the noise of null value, thereby obtain the effective frequency domain sequence signal R that M is ordered _Eff

R _eff(k)＝C(k) k＝1，…，M

With R _EffDo M point IDFT conversion through M point IDFT module, obtain effective time domain sequences signal r _Eff, give next step channel estimating interference eliminated.

Shown in Fig. 7-A, the disposed of in its entirety of interference eliminated comprises relevant and goes to be disturbed.

The conjugation of coherent reference pilot frequency sequence and the inner product of receiving sequence are handled, and go to disturb to comprise that removal multi-user interference and multipath disturb two steps.

Shown in Fig. 7-B, in the channel estimating interference cancellation module, at first at receiving terminal according to different user, generate one group and comprise the long CAZAC checking sequence of ordering for M of M.This group CAZAC checking sequence is to be made M cyclic shift and obtained the method for the similar transmitter generation of production method pilot frequency sequence by the effective pilot tone time domain sequences of targeted customer's CAZAC.For example under the bandwidth of 5M, promptly

$e_{i,j}\left(k\right)=\left\{\begin{array}{ccc}{a}_i(k+151-j)& \mathrm{if}& 0<k\&le;j\\ a_i(k-j)& \mathrm{if}& j<k\&le;M\end{array}\right.$

1≤j≤151 wherein, when j=0, e _{I, 0}(k)=α _i(k).

With e _{I, j}Get after the conjugation and pilot tone time domain sequences r _Eff(the pilot tone time domain sequences is produced by the M point IDFT conversion of DFT-S OFDM demodulation module) makes inner product operation, i.e. premultiplication e _{I, j} ^*(e _{I, j}The Hermitian transposition), obtain $e_{i,j}^{*}{r}_{\mathrm{eff}}={\left|e_{i,j}\right|}^2{h}_{i,j}.$

So, can obtain each time domain impulse response directly of channel $h_{i,j}=\frac{e_{i,j}^{*}{r}_{\mathrm{eff}}}{{\left|e_{i,j}\right|}^2},$ Each user τ in relative time delay _iSatisfy 0 ≡ τ ₁=min{ τ ₁, τ ₂..., τ ₆}≤τ ₂≤ ... ≤ τ ₆≡ max{ τ ₁, τ ₂..., τ ₆, and

That is, according to the corresponding α that counts of maximum multipath time delay _i, and each footpath impulse response h of gained channel _{I, j}

As described in Fig. 7-C, extract the effective value of above-mentioned impulse response sequence front end, the minimum of rear end wherein is used as noise and zero setting is eliminated.This process is exactly the multipath channel interference cancellation process, for example: at the TU3 channel model, 6 footpaths, maximum multipath time-delay 18 points of counting, in this channel, desirable time domain impulse response sequence preceding 20 as effective value, with other zero setting.Obtain ${\hat{h}}_{i,j}=\left\{\begin{array}{ccc}{h}_{i,j}& \mathrm{if}& 0<j\&le;j_{\mathrm{eff}}\\ 0& \mathrm{if}& j_{\mathrm{eff}}<j\&le;M\end{array}\right.$ Wherein, j _EffThe effective diameter number of expression impulse response sequence.

At last, to the time domain impulse response sequence of channel

Do the FFT conversion that M is ordered, can obtain the frequency domain response H of channel _{I, j}

As shown in Figure 8, be a kind of on the basis that Fig. 7-A, Fig. 7-B, Fig. 7-C handles, the interference cancellation module of simplifying has been omitted the processing procedure of the effective value that extracts impulse response sequence front end in this is handled.

As shown in Figure 9, be the receiver of the time-domain pilot signal of the receiving code field orthogonal simplified, comprise that frame decomposes and goes the CP module, simplifies the channel estimating interference cancellation module.

Reception antenna receives and contains yard wireless signal of the pilot signal of territory quadrature, frame decomposes and goes the CP module at first the time-domain signal that reception antenna receives to be carried out the subframe operation splitting, carry out the operation of separation of C P then, the time-domain pilot signal of the sign indicating number territory quadrature that obtains from the subframe signal, separating, time-domain pilot signal is removed multi-user interference and multipath interference, output user's time domain or domain channel response by simplifying the channel estimating interference cancellation module.

The difference of the technical scheme of the receiver channel estimation scheme of this simplification and the receiver of Fig. 7-A and Fig. 7-B is to have omitted to the DFT conversion in the demodulating process of the DFT-S OFDM that receives pilot signal, separates subcarrier mapping and IFFT conversion process, directly original time-domain signal is handled, rather than to handling through the time-domain signal of DFT and IFFT conversion.

As shown in figure 10, be the concrete structure of channel estimating interference cancellation module in the receiver of simplifying.It is different to the channel estimating interference cancellation module of Fig. 7-C, Fig. 8 with Fig. 7-A to simplify the channel estimating interference cancellation module.

Simplify the channel estimating interference cancellation module and comprise M point target user CAZAC sequence generator, circular shift module, M point DFT conversion module, M is to N point subcarrier mapping block, N point IFFT conversion module, inner product summation module, all the other zero setting modules of extraction front end effective value, N point FFT module.

Receiver inside by M point target user CAZAC sequence generator, is used to generate the CAZAC sequence that M is ordered in advance, sends to circular shift module; Circular shift module to the CAZAC sequence cyclic shift of M dot generation, sends to M point DFT conversion module; M point DFT conversion module carries out the DFT conversion to the CAZAC sequence after the displacement, sends to M to N subcarrier mapping block; M is to N subcarrier mapping block, carries out the mapping of the subcarrier that M point subcarrier orders to N, and the frequency domain despreading of finishing is to received signal handled, and extracts the frequency domain information on the receiving sequence, sends to N point IFFT module; N point IFFT module is converted to time domain sequences with frequency domain sequence, constitutes the DFT-S OFDM time-domain signal of CAZAC orthogonal pilot frequency sequence, and sends to the inner product summation module; The inner product summation module, to carry out inner product relevant with the DFT-S OFDM time-domain signal that receives, and obtains time domain channel and estimate response.

If, also can constitute frequency domain channel and estimate response again through N point FFT.Here after inner product is correlated with, also can increase the processing of extracting all the other zero setting of front end effective value before the N point FFT, can eliminate the interference of time domain multipath signal.

Claims (10)

1. a uplink multi-user code field pilot channel estimating system comprises transmitting antenna and reception antenna, it is characterized in that, also comprises:

The training sequence maker is used to generate the pilot frequency sequence that M is ordered, and the pilot frequency sequence that M is ordered is sent into DFT-S OFDM modulation module then;

DFT-S OFDM modulation module is modulated the pilot frequency sequence that the M that receives is ordered, and the pilot signal after the modulation is sent to into frame module;

Become frame module, receive the pilot frequency sequence after DFT-S OFDM modulation module is modulated,, export described transmitting antenna to and send the synthetic subframe of the pilot group after the modulation;

Reception antenna receives the time domain wireless signal that contains yard pilot signal of territory quadrature of described transmitting antenna;

The frame decomposing module, the time-domain signal that reception antenna is received carries out the subframe decomposition, the time-domain pilot signal of the sign indicating number territory quadrature that obtains separating from the subframe signal;

DFT-S OFDM demodulation module carries out demodulation to the time-domain pilot signal that receives, and the pilot signal after the demodulation sends to the channel estimating interference cancellation module;

The channel estimating interference cancellation module is removed multi-user interference and multipath and is disturbed, output user's time domain or domain channel response.

2. the transmitter of the pilot signal of a transmitting code field orthogonal comprises transmitting antenna, it is characterized in that, also comprises:

The training sequence maker is used to generate the pilot frequency sequence that M is ordered, and the pilot frequency sequence that M is ordered is sent into DFT-S OFDM modulation module then;

DFT-S OFDM modulation module is modulated the pilot frequency sequence that the M that receives is ordered, and the pilot signal after the modulation is sent to into frame module;

Become frame module, receive the pilot frequency sequence after DFT-S OFDM modulation module is modulated,, export described transmitting antenna to and transmit the synthetic subframe of the pilot group after the modulation.

3. the transmitter of the pilot signal of transmitting code field orthogonal according to claim 2 is characterized in that, described DFT-S OFDM modulation module comprises M point modular converter, subcarrier mapping block and N point IFFT module; Wherein,

M point modular converter is used for converting time domain sequences to frequency domain sequence;

The subcarrier mapping block is used to finish the mapping of the subcarrier that M point subcarrier in the frequency domain orders to N;

N point IFFT module is used for frequency domain training sequence is converted to time-domain training sequence.

4. the receiver of the pilot signal of a receiving code field orthogonal comprises reception antenna, it is characterized in that, also comprises frame decomposing module, DFT-S OFDM demodulation module, channel estimating interference cancellation module; Wherein,

Reception antenna receives the time domain wireless signal that contains yard pilot signal of territory quadrature;

The frame decomposing module, the time-domain signal that reception antenna is received carries out the subframe decomposition, the time-domain pilot signal of the sign indicating number territory quadrature that obtains separating from the subframe signal;

DFT-S OFDM demodulation module carries out demodulation to the time-domain pilot signal that receives, and the pilot signal after the demodulation sends to the channel estimating interference cancellation module;

The channel estimating interference cancellation module is removed multi-user interference and multipath and is disturbed, output user's time domain or domain channel response.

5. the receiver of the pilot signal of receiving code field orthogonal according to claim 5 is characterized in that, described DFT-S OFDM demodulation module comprises N point FFT module, subcarrier inverse mapping module and M point IDFT module; Wherein,

N point FFT module is converted to frequency-region signal with time-domain signal, sends to subcarrier inverse mapping module;

Subcarrier inverse mapping module is carried out the inverse mapping of the subcarrier that N point subcarrier orders to M, and the frequency domain despreading of finishing is to received signal handled, and extracts the frequency domain information on the receiving sequence, sends to M point IDFT module;

M point IDFT module is carried out M point IDFT conversion, obtains time domain sequences signal and transmission.

6. the method for the pilot signal of a transmitting code field orthogonal comprises the steps:

(1) generates the orthogonal pilot frequency sequence that M is ordered;

(2) orthogonal pilot frequency sequence is carried out DFT-S OFDM modulation;

(3) pilot signal after the emission framing.

7. the pilot signal of a receiving code field orthogonal is carried out the method for channel estimating, comprises the steps:

(1) reception contains yard time-domain signal of the pilot signal of territory quadrature;

(2) time-domain signal is carried out subframe and decompose, obtain yard time-domain pilot signal of territory quadrature;

(3) carry out DFT-S OFDM demodulation;

(4) remove multi-user interference and multipath and disturb, output user's time domain or domain channel response.

8. the receiver of the pilot signal of the receiving code field orthogonal of a simplification comprises reception antenna, is used to receive contain yard wireless signal of the pilot signal of territory quadrature, it is characterized in that, also comprises the frame decomposition and goes CP module, simplification channel estimating interference cancellation module; Wherein,

Frame decomposing module and go the CP module, the time-domain signal that described reception antenna is received are carried out subframe and are decomposed and remove CP, and the time-domain pilot signal of the sign indicating number territory quadrature that obtains separating from the subframe signal sends to the channel estimating interference cancellation module;

Simplify the channel estimating interference cancellation module, remove multi-user interference and multipath and disturb, output user's time domain or domain channel response.

9. the receiver of the pilot signal of the receiving code field orthogonal of simplification according to claim 1 is characterized in that, described simplification channel estimating interference cancellation module comprises:

M point target user CAZAC sequence generator is used to generate the CAZAC sequence that M is ordered, and sends to circular shift module;

Circular shift module to the CAZAC sequence cyclic shift of M dot generation, sends to M point DFT conversion module;

M point DFT conversion module carries out the DFT conversion to the CAZAC sequence after the displacement, sends to M to N subcarrier mapping block;

M is to N subcarrier mapping block, carries out the mapping of the subcarrier that M point subcarrier orders to N, and the frequency domain despreading of finishing is to received signal handled, and extracts the frequency domain information on the receiving sequence, sends to N point IFFT module;

N point IFFT module is converted to time domain sequences with frequency domain sequence, constitutes the DFT-S OFDM time-domain signal of CAZAC orthogonal pilot frequency sequence, and sends to the inner product summation module;

The inner product summation module, to carry out inner product relevant with the DFT-S OFDM time-domain signal that receives, and obtains time domain channel and estimate response.

10. the pilot signal of the receiving code field orthogonal of a simplification is carried out the method for channel estimating, comprises the steps:

(1) reception contains yard time-domain signal of the pilot signal of territory quadrature;

(2) time-domain signal is carried out the subframe operation splitting and removes CP, obtain yard time-domain pilot signal of territory quadrature;

(3) remove multi-user interference and multipath and disturb, output user's time domain or domain channel response.

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