CN1980114A - Channel estimation emitting-receiving device and method - Google Patents

Abstract

The invention includes following devices: (1) frequency domain (FD) pilot carrier (PC) generation device in use for generating a parallel PC in FD; (2) PC mapping device maps PC sequence in FD to corresponding sub carrier, and transfers 0 to sub carrier without PC mapping; thus, input parallel PC sequence in FD is converted to corresponding N points PC sequence in FD; N is equal to length of data block; (3) N points IFFT transform device is in use for carrying out IFFT transform for input mapped N points sequence so as to generate PC sequence in time domain of cascaded multiple identical sequences; PC sequence truncate device in use for truncating sequence in time domain outputted after IFFT transform i.e. fetching part of sequence from multiple identical sequences. Under condition of ensuring performance of estimating channel, the invention shortens length of PC, reduces PC spending so as to raise efficiency of frequency spectrum.

Description

A kind of emission of channel estimating, receiving system and method thereof

Technical field

The present invention relates to emission, receiving system and the method for a kind of fdma system (FDMA) channel estimating, relate in particular to a kind of time domain pilot sequence generator and method thereof.

Background technology

At present, fdma system commonly used is by two kinds, and a kind of is multi-carrier frequency division multiple access (MC-FDMA) system, and another kind is single-carrier frequency division multiple access (SC-FDMA) system.Based on the fdma system of multi-carrier modulation technology, it is low to have an implementation complexity, advantage such as the time-frequency granularity is little, and the frequency domain equalization complexity is little.Its major defect is a transmit signal power peak-to-average force ratio height, and Time and Frequency Synchronization required precision height is easily because the synchronous bad inter-user interference that causes influences the overall performance of communicating by letter.Therefore, multi-carrier frequency division multiple access (MC-FDMA) technology generally is used for the down link of wideband wireless mobile communication.Single-carrier frequency division multiple access is that put forward in the world in recent years a kind of both possessed single carrier communication low-power peak-to-average force ratio characteristic, possesses the novel fdma communication systems that multi-carrier communication is realized simple and scheduling of resource flexible nature again.Generally speaking, because each carrier wave is relatively independent in the single carrier-frequency division multiple access system, simultaneously the bandwidth of each carrier wave is much larger than the bandwidth of multi-carrier frequency division multiple access systems sub-carriers, make single carrier-frequency division multiple access system to the requirement of Time and Frequency Synchronization also far below multi-carrier frequency division multiple access systems.Therefore, the single-carrier frequency division multiple access technology is more suitable for the up link solution in wide-band mobile communication.

In multi-address communication system, generally adopt the piece transmission means based on packet switching.Can adopt simple single-point frequency domain equalization to reduce the receiver complexity based on the piece transmission of Cyclic Prefix.The general employing based on the auxiliary channel estimation methods of pilot tone of the channel frequency response that is used for frequency domain equalization estimated.The pilot tone that is used for channel estimating both can be a pilot tone, also can be the time domain pilot sequence.

The method of pilot tone is the known frequency pilot sign of transmission receiving terminal on some subcarriers that send signal, at all the other subcarrier transmitting data symbols, obviously this method only is suitable for the narrower multicarrier system of subcarrier bandwidth, and is not suitable for the single-carrier system of subcarrier bandwidth broad.In addition, pilot tone is subjected to the restriction of channel coherence bandwidth at interval in the insertion of frequency domain.When the frequency domain number of pilot tone is less when causing pilot interval near the coherence bandwidth of channel, the estimated performance of the subchannel data that will severe exacerbation obtains by interpolation; And when the frequency domain number of pilot tone more for a long time, the system spectrum utilance will reduce again.

The method of time domain pilot sequence is to send a pilot blocks every several data blocks.Pilot blocks both can by correlation properties preferably time domain sequences constitute, also can obtain through discrete inverse Fourier transform by pilot tone.When pilot blocks when time domain sequences constitutes preferably by correlation properties, receiving terminal can estimate that by cross-correlation operation the channel of whole system bandwidth correspondence is corresponding.And when adopting the pilot blocks that pilot tone obtains, receiving terminal can only estimate as required that then the channel of single CU frequency band is corresponding.In the multi-address system up link, to disturb for avoiding multiple access, each user's pilot signal must be at time domain or frequency domain quadrature.For the channel estimating that adopts the time domain sequences pilot blocks, the pilot block length of each subscriber signal is generally the product that channel delay length and system support maximum number of user simultaneously.When channel delay length and system support maximum number of user more simultaneously, the length of pilot blocks will be greater than the length of data block.And when adopting a plurality of transmitting antenna, the length of pilot blocks will be multiplied, and this will have a strong impact on the availability of frequency spectrum of system.In fdma system, because each user only takies the part of whole system bandwidth.For the channel estimating of the pilot blocks that adopts pilot tone to obtain, the length of pilot blocks is the length of data block to the maximum.

The time-varying characteristics of channel are depended at the interval of pilot blocks, and when channel variation was very fast, the time interval that pilot blocks is inserted must reduce, thereby causes the expense of pilot blocks to increase.At this moment, must further reduce the length of pilot blocks.

Summary of the invention

Technical problem to be solved by this invention provides a kind of channel estimation methods and device thereof of fdma system, and it can reduce the length of pilot blocks, thereby reduces pilot-frequency expense, improves the availability of frequency spectrum of system.

The invention provides a kind of channel estimating emitter, comprising:

The pilot tone generating apparatus, be used to generate a parallel frequency-domain pilot sequence;

The pilot tone mapping device, it uniformly-spaced is mapped to frequency-domain pilot sequence on the corresponding subcarrier, to there not being the subcarrier transmission 0 of pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N point frequency-domain pilot sequence like this, describedly equals data block length at the N point;

The IFFT converting means that N is ordered, be used for to the input through the mapping the N point sequence carry out N point IFFT conversion, generate the time domain pilot sequence of the cascade of a plurality of identical sequences;

Pilot frequency sequence brachymemma device, be used to intercept the time domain sequences of exporting after the IFFT conversion, promptly get the partial sequence in a plurality of identical sequences in this time domain sequences.

Accordingly, channel estimating receiving system of the present invention comprises:

The pilot frequency sequence reconfiguration device, the time domain pilot sequence that receives is repeated cascade, constitute the sequence that N is ordered;

N point FFT converting means, be used for to the input sequence carry out the FFT conversion that N is ordered, output sequence is the frequency domain sequence that N is ordered;

Pilot tone is separated mapping device, is used for the pilot frequency mapping method according to transmitting terminal pilot frequency sequence generating apparatus, extracts the pilot tone signal through channel fading on corresponding subcarrier from the sequence of N point FFT conversion output;

Pilot tone point channel estimating apparatus is used for estimating the frequency response of corresponding pilot tone point according to the pilot transmitted signal from the pilot tone signal through channel fading that extracts;

Non-pilot tone point interpolation device is used for estimating the channel frequency response of all the other subcarriers between the pilot tone point by interpolation from the channel frequency response of the pilot tone point of estimating.

Another kind of channel estimating emitter of the present invention comprises:

The pilot tone generating apparatus, be used to generate a parallel frequency-domain pilot sequence;

The pilot tone mapping device, frequency-domain pilot sequence is mapped on the corresponding subcarrier, for the subcarrier transmission 0 that does not have the pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N like this ' the some frequency-domain pilot sequence, described N ' point equals pilot block length;

N ' some IFFT converting means is used for the N ' point sequence through mapping of input is carried out N ' some IFFT conversion, generates N ' some time domain pilot sequence.

Accordingly, channel estimating receiving system of the present invention comprises:

N ' puts the FFT converting means, is used for the sequence time domain pilot sequence of input is carried out N ' FFT conversion, and output sequence is N ' a frequency domain sequence;

Pilot tone is separated mapping device, is used for the pilot frequency mapping method according to transmitting terminal pilot frequency sequence generating apparatus, extracts the pilot tone signal through channel fading on corresponding subcarrier from the sequence of N ' some FFT conversion output;

Pilot tone point channel estimating apparatus is used for estimating the frequency response of corresponding pilot tone point according to the pilot transmitted signal from the pilot tone signal through channel fading that extracts;

Non-pilot tone point interpolation device is used for estimating the channel frequency response of all the other subcarriers between the pilot tone point by interpolation from the channel frequency response of the pilot tone point of estimating.

Simultaneously, the present invention also provides a kind of channel estimating launching technique, comprises the steps: at first, generates a parallel frequency-domain pilot sequence; Frequency-domain pilot sequence uniformly-spaced is mapped on the corresponding subcarrier, and to there not being the subcarrier transmission 0 of pilot tone mapping, the frequency-domain pilot sequence that walks abreast of input is transformed into corresponding N point frequency-domain pilot sequence like this, describedly equals data block length at the N point; The N point sequence through mapping to input carries out N point IFFT conversion, generates the time domain pilot sequence by the cascade of a plurality of identical sequences; The time domain sequences of exporting after the intercepting IFFT conversion is promptly got the partial sequence in a plurality of identical sequences in this time domain sequences.

Described partial sequence is the preceding N ' point data of described time domain sequences, and described N ' point is that the length of pilot blocks, described N are the integral multiple of N '.

Another kind of channel estimating launching technique of the present invention comprises the steps: at first, generates a parallel frequency-domain pilot sequence; Frequency-domain pilot sequence is mapped on the corresponding subcarrier, and for the subcarrier transmission 0 that does not have the pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N like this ' the some frequency-domain pilot sequence, described N ' point equals pilot block length; The N ' point sequence through mapping to input carries out N ' some TFFT conversion, generates N ' some time domain pilot sequence.

Correspondingly, a kind of channel estimating method of reseptance of the present invention comprises the steps: that the time domain pilot sequence that will receive repeats cascade, constitutes the sequence that N is ordered; Sequence to input is carried out the FFT conversion that N is ordered, and output sequence is the frequency domain sequence that N is ordered; According to the pilot frequency mapping method in the transmitting terminal pilot frequency sequence generating apparatus, on corresponding subcarrier, from the sequence of N point FFT conversion output, extract pilot tone signal through channel fading; From the process pilot tone signal of channel fading that extracts, estimate the frequency response of corresponding pilot tone point according to the pilot transmitted signal; From the channel frequency response of the pilot tone point estimated, estimate the channel frequency response of all the other subcarriers between the pilot tone point by interpolation.

A kind of channel estimating method of reseptance comprises the steps: the time domain pilot sequence of input is carried out N ' FFT conversion, and output sequence is N ' a frequency domain sequence; According to the pilot frequency mapping method in the transmitting terminal pilot frequency sequence generating apparatus, on corresponding subcarrier, from the sequence of N ' some FFT conversion output, extract pilot tone signal through channel fading; From the process pilot tone signal of channel fading that extracts, estimate the frequency response of corresponding pilot tone point according to the pilot transmitted signal; From the channel frequency response of the pilot tone point estimated, estimate the channel frequency response of all the other subcarriers between the pilot tone point by interpolation.

The present invention has shortened the length of pilot tone under the condition that guarantees channel estimating performance, reduced the expense of pilot tone, thereby improved the spectrum efficiency of system.

Description of drawings

Fig. 1 is the channel estimating emitter schematic diagram of fdma system of the present invention.

Fig. 2 is the structural representation of an embodiment of time domain pilot sequence generator shown in Figure 1.

Fig. 3 is the structural representation of another embodiment of time domain pilot sequence generator shown in Figure 1.

Fig. 4 is that the single carrier-frequency division multiple access system pilot tone of M sub-frequency bands is inserted schematic diagram.

Fig. 5 is the channel estimating receiving system schematic diagram of fdma system of the present invention.

Fig. 6 is the structural representation of an embodiment of pilot tone extraction element shown in Figure 5.

Fig. 7 is the structural representation of another embodiment of pilot tone extraction element shown in Figure 5.

Fig. 8 is the channel estimating performance analogous diagram of fdma system of the present invention.

Embodiment

As shown in Figure 1: the channel estimating emitter of fdma system of the present invention comprises successively and to connect:

Pilot tone generating apparatus 1, be used to generate a parallel frequency-domain pilot sequence { P _k, k=0,1,2 ..., N _P-1}, wherein, N _PBe the pilot tone number.This number depends on the bandwidth that needs estimated channel and the coherence time of channel.

Time domain pilot sequence generator 2, with frequency-domain pilot sequence { P _k, k=0,1,2 ..., N _P-1} uniformly-spaced is mapped on the corresponding subcarrier, and the subcarrier transmission 0 to there not being pilot tone to shine upon makes, obtains the time domain pilot sequence after the frequency-domain pilot sequence process IFFT conversion that input walks abreast.

The protection that at interval adding set 3 of protection, the head or tail portion in the time domain pilot sequence of above-mentioned generation of being used for add a length-specific is used to reduce interchannel interference (length at this protection interval should greater than channel maximum delay extension length) at interval.Preferably, protection adding set at interval can be adopted Cyclic Prefix (CP) adding set, and a part that also is about to described data block afterbody copies to its front end, forms the data block symbols of final band CP.Through Cyclic Prefix adding set, input block sequence { d _k, k=0,1,2 ..., N '-1} is transformed into the time domain pilot sequence { e that complete length is N '+C _k, k=0,1,2 ..., N '+C-1}.Here, C is a circulating prefix-length.

Need to prove, as the relevant channel coding device with transfer of data of digital communication system transmitter necessary component, digital modulation device, a RF converter plant and a transmitting antenna and purpose of the present invention there is no direct relation, are not described at this.

Wherein, time domain pilot sequence generator 2 can have two kinds of implementations, represents in Fig. 2 and Fig. 3 respectively.In implementation one, time domain pilot sequence generator 2 comprises successively and to connect:

A pilot tone mapping device 20, the bandwidth of the subchannel that is used for estimating as required, frequency location, pilot interval and number of transmit antennas are with frequency-domain pilot sequence { P _k, k=0,1,2 ..., N _P-1} is mapped on the corresponding subcarrier, for the subcarrier transmission 0 that does not have the pilot tone mapping.For adopting N _TThe system of individual transmitting antenna, pilot interval is at least 2N _T, promptly every 2N _T-1 subcarrier inserts 1 pilot tone, all the other subcarrier zero insertions.This pilot interval must be N _TIntegral multiple.Fig. 4 is that single carrier-fdma system pilot tone that the M sub-frequency bands is arranged is inserted pattern.Its insertion method is, at first calculates the shared number of sub carrier wave of each sub-band, and counting for IFFT is that N, sub-band number are the system of M, and the shared number of sub carrier wave of each sub-band is N/M.Then, calculate the pilot tone initial frequency position P of m sub-frequency bands _M0, and P _M0=m * N/M.The subcarrier sequence number of calculating the pilot frequency sequence of m sub-frequency bands at last is P _MInd=P _M0+ D * d, d=0,1 ..., N _m-1, wherein D is a pilot interval, N _m(M * D) is the required number of pilots of m sub-frequency bands to=N/.Pilot interval D depends on the subcarrier bandwidth that channel coherence bandwidth and IFFT transfer pair are answered, and preferably, pilot interval D value is 2 integer power power, as 2,4,8 etc.Through the pilot tone mapping device, the frequency-domain pilot sequence { P that input is parallel _k, k=0,1,2 ..., N _P-1} is transformed into corresponding frequency domain symbol sequence { b _k, k=0,1,2 ..., N-1}, wherein N equals the size of IFFT conversion thereafter.IFFT conversion points N equals the length of communication system data piece.

The IFFT converting means 21 that N is ordered, be used for parallel symbol sequence { b to input _k, k=0,1,2 ..., N-1} carries out N point IFFT conversion.As in single carrier-fdma system, the length of data block is the size of frequency domain equalization; In the multicarrier-fdma system based on the OFDM technology, the length of data block is the OFDM symbol lengths.Through IFFT converting means, the parallel symbol sequence { b of input _k, k=0,1,2 ..., N-1} is transformed into corresponding time domain sequences { c _k, k=0,1,2 ..., N-1}, relation is each other obeyed c _k=IFFT (b _k);

A pilot frequency sequence brachymemma device 22 is used for the time domain sequences { c that brachymemma IFFT conversion is exported _k, k=0,1,2 ..., N-1} promptly gets the preceding N ' point data of time domain sequences.Preferably, select truncated sequence length to make that the points N of above-mentioned IFFT conversion is the integral multiple of N ', and the points N of above-mentioned IFFT conversion is at least the twice of N '.Through pilot frequency sequence brachymemma device, the time domain sequences of input is transformed to sequence { d _k, k=0,1,2 ..., N '-1}.

Because the length of data block is N, the length of the pilot blocks of receiving terminal also is necessary for N, just can finish the equilibrium of frequency domain single-point.If the pilot transmitted block length is N, and is out of question certainly.But this moment, efficiency of transmission can reduce.If the pilot transmitted block length is less than N, and can reconstruct length be the pilot blocks of N again at receiving terminal, then the pilot frequency sequence that produces of transmitting terminal must be a periodic signal, and promptly a plurality of identical sequences are cascaded into the pilot frequency sequence that length is N.When only transmitting one of them sequence, also can recover other parts like this, to reconstruct the pilot blocks that length is N at receiving terminal.In this programme, length is that the pilot frequency sequence of N is that the pilot blocks of N ' constitutes by several same length, only transmit the pilot blocks that length is N ' in the present invention, so pilot block length has reduced.

Accordingly, the channel estimating launching technique of this programme comprises the steps: at first, generates a parallel frequency-domain pilot sequence; Frequency-domain pilot sequence uniformly-spaced is mapped on the corresponding subcarrier, and to there not being the subcarrier transmission 0 of pilot tone mapping, the frequency-domain pilot sequence that walks abreast of input is transformed into corresponding N point frequency-domain pilot sequence like this, describedly equals data block length at the N point; The N point sequence through mapping to input carries out N point IFFT conversion, generates the time domain pilot sequence of the cascade of a plurality of identical sequences; Intercept the time domain sequences of exporting after the IFFT conversion, promptly get the preceding N ' point data of this time domain sequences, described N ' point is that the length of pilot blocks, described N are the integral multiple of N '.

In implementation two, time domain pilot sequence generator 2 comprises successively and to connect:

Pilot tone mapping device 23, the bandwidth of the subchannel that is used for estimating as required, frequency location, pilot interval and number of transmit antennas are with frequency-domain pilot sequence { P _k, k=0,1,2 ..., N _P-1} is mapped on the corresponding subcarrier, for the subcarrier transmission 0 that does not have the pilot tone mapping.For adopting N _TThe system of individual transmitting antenna, pilot interval is at least N _T, promptly every N _T-1 subcarrier inserts 1 pilot tone, all the other subcarrier zero insertions; Fig. 4 is that single carrier-fdma system pilot tone that the M sub-frequency bands is arranged is inserted pattern.Its insertion method is, at first calculates the shared number of sub carrier wave of each sub-band, and counting for IFFT is that N ', sub-band number are the system of M, and the shared number of sub carrier wave of each sub-band is N '/M.Then, calculate the pilot tone initial frequency position P of m sub-frequency bands _M0, and P _M0=m * N '/M.The subcarrier sequence number of calculating the pilot frequency sequence of m sub-frequency bands at last is P _MInd=P _M0+ D ' * d, d=0,1 ..., N _m-1, wherein D ' is a pilot interval, N _m=N '/(M * D) is the required number of pilots of m sub-frequency bands.Pilot interval D ' depends on the subcarrier bandwidth that channel coherence bandwidth and IFFT transfer pair are answered, and preferably, pilot interval D value is 2 integer power power, as 1,2,4,8 etc.Through the pilot tone mapping device, the frequency-domain pilot sequence { P that input is parallel _k, k=0,1,2 ..., N _P-1} is transformed into corresponding frequency domain symbol sequence { b _k', k=0,1,2 ..., N '-1}, wherein N ' equals the size of IFFT conversion thereafter.

N ' some IFFT converting means 24 is used for the parallel symbol sequence { b to input _k', k=0,1,2 ..., N '-1} carries out N ' some IFFT conversion.The length of the time domain pilot sequence of IFFT conversion points N ' equal to send.Select the length of time domain pilot sequence to make the length of communication system data piece be its integral multiple.As in single carrier-fdma system, the length of data block is the size of frequency domain equalization; In the multicarrier-fdma system based on the OFDM technology, the length of data block is the OFDM symbol lengths.Preferably, select the length of time domain pilot sequence to make that above-mentioned data block length N is the integral multiple of N ', and make above-mentioned data block length N be at least the twice of N '.Through N ' some IFFT converting means, the parallel symbol sequence { b of input _k', k=0,1,2 ..., N '-1} is transformed into corresponding time domain sequences { d _k, k=0,1,2 ..., N '-1}, relation is each other obeyed d _k=IFFT (b _k');

Accordingly, the channel estimating launching technique of this programme comprises the steps, at first, generates a parallel frequency-domain pilot sequence; Frequency-domain pilot sequence is mapped on the corresponding subcarrier, and for the subcarrier transmission 0 that does not have the pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N like this ' the some frequency-domain pilot sequence, described N ' point equals pilot block length; The N ' point sequence through mapping to input carries out N ' some IFFT conversion, generates N ' some time domain pilot sequence.

As shown in Figure 5: the string character sequence that is assumed to the Cyclic Prefix removal device 5 that is input to emitter/receiver; And supposition receiver ideal synchronisation.The channel estimating receiving system of fdma system of the present invention comprises connection successively:

Protection is removal device 5 at interval, is used for according to the structure of the time domain pilot sequence of launching the individual sampled value of preceding C (C is a circulating prefix-length) of the pilot frequency sequence of reception being cast out, and forming length is the serial data block sequence of N ';

Pilot tone extraction element 6 is used for the time domain pilot sequence { g to receiving _k, k=0,1,2 ..., N ') carry out the FFT conversion, output sequence is a frequency domain sequence.And extract the pilot tone signal of process channel fading according to emission pilot sub-carrier position.Corresponding two kinds of pilot frequency sequence generating apparatus, this pilot tone extraction element 6 also can have two kinds of implementation methods.

Pilot tone point channel estimating apparatus 7 is used for estimating the frequency response of corresponding pilot tone point according to the pilot transmitted signal from the pilot tone signal through channel fading that extracts.Preferably, adopt the least-squares estimation algorithm.Particularly, the estimated value of the channel frequency response of k pilot tone point is: $H_k=P_k^{\%}/P_k,k=\mathrm{0,1,2},...,N_p-1$ 。Through pilot tone point channel estimating apparatus, output sequence is $\{H_k=P_k^{\%}/P_k,k=\mathrm{0,1,2},...,N_P-1\};$

Non-pilot tone point interpolation device 8 is used for estimating the channel frequency response of all the other subcarriers between the pilot tone point by interpolation from the channel frequency response of the pilot tone point of estimating.Wherein,, two kinds of interpolation methods are arranged, respectively corresponding two kinds of pilot tone extracting methods according to the difference of pilot tone extracting method.

Need to prove, as the synchronizer of digital communication system receiver necessary component, balancer, channel decoding device and digital demodulating apparatus and purpose of the present invention there is no direct relation, are not described at this.

Two kinds of implementations of described pilot tone extraction element 6, representing in Fig. 6 and Fig. 7 respectively to prove, the pilot tone signal that these two kinds of implementation methods are extracted removes and differs a fixing range coefficient Outward, identical.

As shown in Figure 6, in implementation one, pilot tone extraction element 6 comprises successively and to connect:

Pilot frequency sequence reconfiguration device 61 is used for the time domain pilot sequence { g by receiving _k, k=0,1,2 ..., N ' } time domain sequences of N point IFFT conversion output sequence correspondence in first kind of implementation method of reconstruct transmitting terminal pilot frequency sequence generating apparatus 2.Particularly, N ' the time domain pilot sequence that receives is repeated cascade, constitute the sequence that N is ordered.Through the pilot frequency sequence reconfiguration device, output sequence is the time domain sequences { h that N is ordered _k, k=0,1,2 ..., N};

The FFT converting means 62 that N is ordered is used for the time domain sequences that input N is ordered is carried out the FFT conversion that N is ordered.Through the FFT converting means that N is ordered, output sequence is the frequency domain sequence { i that N is ordered _k, k=0,1,2 ..., N-1};

Pilot tone is separated mapping device 63, is used for the pilot frequency mapping method according to the 1st kind of implementation method of transmitting terminal pilot frequency sequence generating apparatus 2, extracts the pilot tone signal through channel fading on corresponding subcarrier from the sequence of FFT conversion output.Separate mapping device through pilot tone, output sequence is N _PThe frequency-domain pilot sequence of point $\{P_k^{\%},K=\mathrm{0,1,2},...,N_P-1\}.$

Accordingly, the channel estimating method of reseptance of this programme comprises the steps: that N ' the time domain pilot sequence that will receive repeats cascade, constitutes the sequence that N is ordered; Sequence to input is carried out the FFT conversion that N is ordered, output sequence is the frequency domain sequence that N is ordered: according to the pilot frequency mapping method in the transmitting terminal pilot frequency sequence generating apparatus, extract the pilot tone signal through channel fading on corresponding subcarrier from the sequence of N point FFT conversion output; From the process pilot tone signal of channel fading that extracts, estimate the frequency response of corresponding pilot tone point according to the pilot transmitted signal; From the channel frequency response of the pilot tone point estimated, estimate the channel frequency response of all the other subcarriers between the pilot tone point by interpolation.

As shown in Figure 7: in implementation two, pilot tone extraction element 6 comprises successively and to connect:

N ' some FFT converting means 64 is used for the sequence time domain pilot sequence { g to input _k, k=0,1,2 ..., N '-1} carries out N ' FFT conversion.Through N ' FFT converting means, output sequence is N ' frequency domain sequence { j _k, k=0,1,2 ..., N '-1};

Pilot tone is separated mapping device 64, is used for the pilot frequency mapping method according to the 2nd kind of implementation method of transmitting terminal pilot frequency sequence generating apparatus 2, extracts the pilot tone signal through channel fading on corresponding subcarrier from the sequence of FFT conversion output.Separate mapping device through pilot tone, output sequence is N _PThe frequency-domain pilot sequence of point ${\{P}_k^{\%}k=\mathrm{0,1,2},...,N_p-1\};$

For pilot tone extracting method 1, because its FFT transform size that adopts is N, this value is identical with the data block size of frequency domain equalization.Therefore, the channel frequency response of the subcarrier of all the other between the pilot tone point can be directly gets final product according to the pilot interval D interpolation of transmitting terminal.

For pilot tone extracting method 2, because its FFT transform size that adopts is N ', the data block size of frequency domain equalization is the integral multiple of this value.In order to make the required channel frequency response of channel frequency response that interpolation obtains and N point frequency domain equalization consistent, the channel frequency response of all the other subcarriers between the pilot tone point must be according to the L times of interpolation of the pilot interval D ' of transmitting terminal.L=N/N ' wherein;

The channel estimating interpolation algorithm can be a single order, second order or linear minimum mean-squared error interpolation algorithm.

Accordingly, the channel estimating method of reseptance of this incidence of criminal offenses comprises: the sequence time domain pilot sequence to input is carried out N ' FFT conversion, and output sequence is N ' a frequency domain sequence; According to the pilot frequency mapping method in the transmitting terminal pilot frequency sequence generating apparatus, on corresponding subcarrier, from the sequence of N ' some FFT conversion output, extract pilot tone signal through channel fading; From the process pilot tone signal of channel fading that extracts, estimate the frequency response of corresponding pilot tone point according to the pilot transmitted signal; From the channel frequency response of the pilot tone point estimated, estimate the channel frequency response of all the other subcarriers between the pilot tone point by interpolation.

Suppose that the FFT points N that is used for receiver section data block frequency domain equalization is 512, fdma system always has 16 sub-frequency bands, and then each subband occupies 32 frequencies (subcarrier).Suppose that transmitter adopts single transmitting antenna, the frequency-domain pilot sequence that is produced by the pilot tone generation device is p (n), 0≤n≤15, and pilot interval is 2.The time domain pilot sequence length of required generation is N/2, promptly 256.Uncomfortable general, suppose that pilot tone is used to estimate the channel response of the 0th sub-frequency bands, then the corresponding pilot tone in pilot tone mapping back through method 1 correspondence in the time domain pilot sequence generator 2 is:

X(2n)＝p(n)

，0≤n≤15 (1)

X(2n+1)＝0

, the conversion that all pilot tones of 512 are carried out IFFT obtains the pilot tone time domain sequences and is:

$x\left(m\right)={\mathrm{IFFT}}_N\left\{X\left(n\right)\right\}$

$=\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(n\right)W_N^{\mathrm{mn}}$

$=\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}X\left(2n\right){\mathrm{<figure-callout\; id="2"\; label="W\; N"\; filenames="A20051011098800171.png"\; state="\{\{state\}\}">W</figure-callout>}}_N^{}+\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}X(2n+1)W_N^{2m(n+1)},0\&le;m\&le;N-1---\left(2\right)$

$=\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}X\left(2n\right){\mathrm{<figure-callout\; id="2"\; label="W\; N"\; filenames="A20051011098800171.png"\; state="\{\{state\}\}">W</figure-callout>}}_N^{}$

$=\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}X\left(2n\right)W_{N/2}^{\mathrm{mn}}$

Wherein, W _N=e- ^{J2 π/N}Because X (2n)=p (n),

$x\left(m\right)=\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}p\left(n\right)W_{N/2}^{\mathrm{mn}}$

$=\frac{1}{\sqrt{2}\sqrt{N/2}}\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}p\left(n\right)W_{N/2}^{{\left(\left(m\right)\right)}_{{N/2}^n}},0\&le;m\&le;N-1---\left(3\right)$

$=\frac{1}{\sqrt{2}}{\mathrm{IFFT}}_{N/2}\left\{p\left(n\right)\right\}$

Interim, ((x)) _yExpression x mould y computing.

By (3) formula as seen, when pilot interval is 2, be the cascade of two identical version of the time domain sequences that obtains of IFFT that same pilot frequency sequence is ordered through N/2 through the time domain sequences that obtains of IFFT of N (N is 2 integer power power) point.Thereby proof, among the present invention, time domain pilot sequence generator 2, with the time domain pilot sequence of two kinds of implementation methods generations except differing a range coefficient

Outward, identical.Otherwise, can prove that in the pilot tone extraction element 6 of receiving terminal, the pilot tone signal of two kinds of implementation method extractions is except that differing a range coefficient, and is identical.

System emulation and result based on a single carrier-fdma system can draw simulation parameter:

Frequency domain equalization FFT size	512
		The time domain pilot sequence length	256
Circulating prefix-length	32
		Bandwidth	5MHz

Sub-band sum	16
		The sub band number of using	4
Sub-band frequency domain distribution pattern	Discrete distribution/continuous distribution
		Channel model	TU
Carrier frequency	2.4GHz
		Translational speed	3km/h
Chnnel coding/code check	Turbo code/1/2
		Modulation system	QPSK

Wherein, the subband discrete distribution is meant that 4 sub-frequency bands of use are to be spacedly distributed in all 16 sub-frequency bands; The subband continuous distribution is meant that in all 16 sub-frequency bands, 4 sub-frequency bands of use are continuous distribution adjacent one another are.By simulation result as seen, the channel estimating performance that adopts this method than rational performance for estimating channel difference less than about 1dB.

Claims (19)

1, a kind of channel estimating emitter comprises:

The pilot tone generating apparatus, be used to generate a parallel frequency-domain pilot sequence; It is characterized in that, also comprise:

The pilot tone mapping device, it uniformly-spaced is mapped to frequency-domain pilot sequence on the corresponding subcarrier, to there not being the subcarrier transmission 0 of pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N point frequency-domain pilot sequence like this, and described N point equals data block length;

The IFFT converting means that N is ordered, be used for the N point sequence through mapping of input is carried out N point IFFT conversion, generation is by the time domain pilot sequence of the cascade of a plurality of identical sequences;

Pilot frequency sequence brachymemma device, be used to intercept the time domain sequences of exporting after the IFFT conversion, promptly get the partial sequence in a plurality of identical sequences in this time domain sequences.

2, a kind of channel estimating emitter comprises:

The pilot tone generating apparatus, be used to generate a parallel frequency-domain pilot sequence; It is characterized in that, also comprise:

The pilot tone mapping device, frequency-domain pilot sequence is mapped on the corresponding subcarrier, for the subcarrier transmission 0 that does not have the pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N like this ' the some frequency-domain pilot sequence, described N ' point equals pilot block length;

N ' some IFFT converting means is used for the N ' point sequence through mapping of input is carried out N ' some IFFT conversion, generates N ' some time domain pilot sequence.

3, a kind of channel estimating receiving system comprises:

The pilot frequency sequence reconfiguration device, the time domain pilot sequence that receives is repeated cascade, constitute the sequence that N is ordered;

N point FFT converting means, be used for to the input sequence carry out the FFT conversion that N is ordered, output sequence is the frequency domain sequence that N is ordered;

Pilot tone is separated mapping device, is used for the pilot frequency mapping method according to transmitting terminal pilot frequency sequence generating apparatus, extracts the pilot tone signal through channel fading on corresponding subcarrier from the sequence of N point FFT conversion output;

Pilot tone point channel estimating apparatus is used for estimating the frequency response of corresponding pilot tone point according to the pilot transmitted signal from the pilot tone signal through channel fading that extracts;

Non-pilot tone point interpolation device is used for estimating the channel frequency response of all the other subcarriers between the pilot tone point by interpolation from the channel frequency response of the pilot tone point of estimating.

4, a kind of channel estimating receiving system comprises:

N ' puts the FFT converting means, is used for the time domain pilot sequence of input is carried out N ' FFT conversion, and output sequence is N ' a frequency domain sequence;

Pilot tone is separated mapping device, is used for the pilot frequency mapping method according to transmitting terminal pilot frequency sequence generating apparatus, extracts the pilot tone signal through channel fading on corresponding subcarrier from the sequence of N ' some FFT conversion output;

Pilot tone point channel estimating apparatus is used for estimating the frequency response of corresponding pilot tone point according to the pilot transmitted signal from the pilot tone signal through channel fading that extracts;

Non-pilot tone point interpolation device is used for estimating the channel frequency response of all the other subcarriers between the pilot tone point by interpolation from the channel frequency response of the pilot tone point of estimating.

5, a kind of channel estimating launching technique is characterized in that, at first, generates a parallel frequency-domain pilot sequence; Frequency-domain pilot sequence uniformly-spaced is mapped on the corresponding subcarrier, and to there not being the subcarrier transmission 0 of pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N point frequency-domain pilot sequence like this, and described N point equals data block length; The N point sequence through mapping to input carries out N point IFFT conversion, generates the time domain pilot sequence by the cascade of a plurality of identical sequences; The time domain sequences of exporting after the intercepting IFFT conversion is promptly got the partial sequence in a plurality of identical sequences in this time domain sequences.

6, channel estimating emitter according to claim 1 is characterized in that, described partial sequence is the preceding N ' point data of described time domain sequences, and described N ' point is that the length of pilot blocks, described N are the integral multiple of N '.

7, channel estimating launching technique according to claim 5 is characterized in that, the described method that frequency-domain pilot sequence is mapped on the respective sub is:

Its insertion method is, at first calculates the shared number of sub carrier wave of each sub-band, and counting for IFFT is that N, sub-band number are the system of M, and the shared number of sub carrier wave of each sub-band is N/M, then, calculates the pilot tone initial frequency position P of m sub-frequency bands _M0, and P _M0=m * N/M, the subcarrier sequence number of calculating the pilot frequency sequence of m sub-frequency bands at last is P _MInd=P _M0+ D * d, d=0,1 ..., N _m-1, wherein D is a pilot interval, N _m(M * D) is the required number of pilots of m sub-frequency bands to=N/.

According to the described channel estimating launching technique of claim 7, it is characterized in that 8, described pilot interval D depends on the subcarrier bandwidth that channel coherence bandwidth and IFFT transfer pair are answered, preferably, pilot interval D value is 2 integer power power.

9, channel estimating emitter according to claim 8 is characterized in that, for adopting N _TThe system of individual transmitting antenna, described pilot interval is at least 2N _T, promptly every 2N _T-1 subcarrier inserts 1 pilot value, all the other subcarrier zero insertions.

10, channel estimating emitter according to claim 9 is characterized in that, described pilot interval is N _TIntegral multiple.

11, a kind of channel estimating launching technique is characterized in that, at first, generates a parallel frequency-domain pilot sequence; Frequency-domain pilot sequence is mapped on the corresponding subcarrier, and for the subcarrier transmission 0 that does not have the pilot tone mapping, the parallel frequency-domain pilot sequence of input is transformed into corresponding N like this ' the some frequency-domain pilot sequence, described N ' point equals pilot block length; The N ' point sequence through mapping to input carries out N ' some IFFT conversion, generates N ' some time domain pilot sequence.

12, channel estimating launching technique according to claim 11 is characterized in that, the described method that frequency-domain pilot sequence is mapped on the respective sub is:

Its insertion method is, at first calculates the shared number of sub carrier wave of each sub-band, and counting for IFFT is that N ', sub-band number are the system of M, and the shared number of sub carrier wave of each sub-band is N '/M; Then, calculate the pilot tone initial frequency position P of m sub-frequency bands _M0, and P _M0=m * N '/M; The subcarrier sequence number of calculating the pilot frequency sequence of m sub-frequency bands at last is P _MInd=P _M0+ D ' * d, d=0,1 ..., N _m-1, wherein D ' is a pilot interval, N _m=N '/(M * D ') is the required number of pilots of m sub-frequency bands.

13, channel estimating launching technique according to claim 12 is characterized in that, described pilot interval D depends on the subcarrier bandwidth that channel coherence bandwidth and IFFT transfer pair are answered, and preferably, pilot interval D value is 2 integer power power.

14, channel estimating emitter according to claim 12 is characterized in that, for adopting N _TThe system of individual transmitting antenna, pilot interval is at least N _T, promptly every N _T-1 subcarrier inserts 1 pilot value, all the other subcarrier zero insertions.

15, a kind of channel estimating method of reseptance comprises the steps: that the time domain pilot sequence that will receive repeats cascade, constitutes the sequence that N is ordered; Sequence to input is carried out the FFT conversion that N is ordered, and output sequence is the frequency domain sequence that N is ordered; According to the pilot frequency mapping method in the transmitting terminal pilot frequency sequence generating apparatus, on corresponding subcarrier, from the sequence of N point FFT conversion output, extract pilot tone signal through channel fading; From the process pilot tone signal of channel fading that extracts, estimate the frequency response of corresponding pilot tone point according to the pilot transmitted signal; From the channel frequency response of the pilot tone point estimated, estimate the channel frequency response of all the other subcarriers between the pilot tone point by interpolation.

16, channel estimating method of reseptance according to claim 15 is characterized in that, described pilot extraction method is: the channel frequency response of all the other subcarriers between the pilot tone point can be directly according to the pilot interval D interpolation of transmitting terminal.

17, a kind of channel estimating method of reseptance comprises: the time domain pilot sequence to input is carried out N ' FFT conversion, and output sequence is N ' a frequency domain sequence; According to the pilot frequency mapping method in the transmitting terminal pilot frequency sequence generating apparatus, on corresponding subcarrier, from the sequence of N ' some FFT conversion output, extract pilot tone signal through channel fading; From the process pilot tone signal of channel fading that extracts, estimate the frequency response of corresponding pilot tone point according to the pilot transmitted signal; From the channel frequency response of the pilot tone point estimated, estimate the channel frequency response of all the other subcarriers between the pilot tone point by interpolation.

18, channel estimating method of reseptance according to claim 17, it is characterized in that, described pilot tone extracting method is: the channel frequency response of all the other subcarriers between the pilot tone point must be according to L times of interpolation, the wherein L=N/N ' of the pilot interval D ' of transmitting terminal.

19, channel estimating method of reseptance according to claim 17 is characterized in that, the method that the frequency of the corresponding pilot tone point of described estimation is rung rate is to adopt the least-squares estimation algorithm.

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