CN103647734B - Channel for satellite mobile communication terminal is estimated and the method and device of equilibrium - Google Patents

Abstract

The invention provides a kind of channel for satellite mobile communication terminal to estimate and the method and device of equilibrium, relate to field of satellite mobile communication, including: the docking collection of letters number carries out channel estimation, utilize the result that channel is estimated, the docking collection of letters number equalizes, and the result of equilibrium is demodulated successively, is deinterleaved and Viterbi decoding, exports Viterbi decoding result, the method farther includes: encode Viterbi decoding result, obtains the bit sequence of coding；The bit sequence of coding is interleaved, obtains the bit sequence interweaved；The bit sequence interweaved is modulated, obtains modulation symbol sequence；Channel estimation is again carried out as the known symbol docking collection of letters number with modulation symbol sequence, export the result that two secondary channels are estimated, it carries out two secondary channel estimations by the docking collection of letters number and secondary equalizes, the channel making shorter training sequence is estimated more accurate, thus substantially increases the performance of adaptive equalization.

Description

For satellite mobile communication terminal channel estimate and equilibrium method and Device

Technical field

The present invention relates to field of satellite mobile communication, move in particular to for satellite The channel of communication terminal is estimated and the method and device of equilibrium.

Background technology

Along with the development of information communication industry, China's land mobile communication system has compared to be sent out Reach.But, owing to China is vast in territory, geographical environment is various, population distribution is uneven, ground Face mobile communication system cover only the area of China 30%, there remains the territory of 70% Area lacks Base communication guarantee.Satellite mobile communication system then can be effective by satellite Extend its coverage, so that can be accessed by user terminal public or special in the world Use communication network.Therefore, satellite mobile communication system is as an important set of ICT industry Become part, national information infrastructure construction, safeguard country unipolitics economic interests, Promote the aspects such as country's disaster prevention emergency ability and there is critical role.

In satellite mobile communication terminal, owing to the multipath effect of channel makes the signal that receives Overlap each other, form intersymbol interference.In order to make the terminal can correctly demodulated signal, it is necessary to Eliminate this intersymbol interference.Generally use channel to estimate and balancing technique processes.Due to The time variation of channel and randomness, need to use adaptive equalization, enable equalizer automatic The change of adaptive channel characteristic, wherein, the realization of the performance of adaptive equalization depends on channel The accuracy estimated.

Channel estimates that being generally basede on training sequence is carried out at present, and correlation technique is based on training sequence The method carrying out channel estimation is as follows: geostationary orbit satellite mobile communication system (GMR-1) TDMA (Time Division Multiple Access, time division multiple acess) is used Transmission means, data are transmitted in bursts, thus utilize burst in unique word, The training sequence y i.e. received, uses minimum variance estimate LS docking collection of letters X to carry out Channel is estimated, the impulse response h of the channel obtained, and is filtered h, is filtered As a result, then filter result is equalized, export equilibrium result, then equal to export Weighing apparatus result is demodulated, deinterleaves and Viterbi decoding, exports Viterbi decoding result.

But, for the system shorter to training sequence, the training sequence y that himself is shorter Channel is estimated not accurate enough, and then also have influence on the performance of adaptive equalization.

Summary of the invention

It is an object of the invention to provide the channel for satellite mobile communication terminal to estimate and equal The method and device of weighing apparatus, to solve above-mentioned problem.

Provide a kind of channel for satellite mobile communication terminal in an embodiment of the present invention The method estimated, including: the docking collection of letters number carries out channel estimation, utilizes the knot that channel is estimated Really, docking is collected mail and number is equalized, the result of equilibrium is demodulated successively, deinterleave and Viterbi decoding, exports Viterbi decoding result, and the method farther includes:

Viterbi decoding result is encoded, obtains the bit sequence of coding；

The bit sequence of coding is interleaved, obtains the bit sequence interweaved；

The bit sequence interweaved is modulated, obtains modulation symbol sequence；

Channel estimation is again carried out as the known symbol docking collection of letters number with modulation symbol sequence, Export the result that two secondary channels are estimated.

Further, coding includes: use convolutional code that Viterbi decoding result is carried out channel Coding；

Intertexture includes: the bit sequence of coding is carried out block interleaving；

Modulation includes: use QPSK signal QPSK to enter the bit sequence interweaved Row modulation.

Further, again carry out channel to estimate to include:

Use minimum variance estimate LS, described modulation symbol sequence is carried out two secondary channels and estimates Meter.

Additionally provide a kind of equal for satellite mobile communication terminal in an embodiment of the present invention The method of weighing apparatus, including:

The secondary that the method estimated according to the above-mentioned channel for satellite mobile communication terminal obtains The result that channel is estimated, the docking collection of letters number equalizes again；

Result after output secondary equilibrium.

Further, again carry out equilibrium to include:

Maximum likelihood sequence valuation MLSE, the docking collection of letters number is used again to equalize.

Further, the MLSE docking collection of letters number is used again to equalize, including:

The viterbi algorithm MVA improved, the docking collection of letters number is used again to equalize.

Further, the result after output secondary equilibrium, including:

Use the mode of soft output, the result after output secondary equilibrium.

Further, the result after using the mode of soft output, output secondary to equalize, specifically Including:

Use the VA algorithm VALPP of band likelihood preprocessor, the knot after output secondary equilibrium Really.

Provide a kind of channel for satellite mobile communication terminal in an embodiment of the present invention The device estimated, including:

Channel estimating unit, is used for docking the collection of letters number and carries out channel estimation, obtain channel Estimated result；

Balanced unit, estimates knot for the channel utilizing channel estimating unit to obtain Really, the docking collection of letters number equalizes, and is equalized result；

Decoding unit, the result of the equilibrium for obtaining balanced unit solves successively Adjust, deinterleave and Viterbi decoding, export Viterbi decoding result；This device also includes:

Coding unit, for encoding the output result of Viterbi decoding, is encoded Bit sequence；

Interleave unit, is interleaved for the bit sequence obtaining coding unit coding, To the bit sequence interweaved；

Modulating unit, is modulated for the bit sequence obtained that interweaves interleave unit, To modulation symbol sequence；

Secondary channel estimating unit, with modulation symbol sequence as the known symbol docking collection of letters number Carry out two secondary channel estimations, export the result that two secondary channels are estimated.

Additionally provide a kind of equal for satellite mobile communication terminal in an embodiment of the present invention The device of weighing apparatus, including:

Above-mentioned channel estimating apparatus, the result estimated for output two secondary channel；

Secondary balanced unit, for the result estimated according to two secondary channels, the docking collection of letters number is entered Row secondary equalizes；

Output unit, the result after exporting the equilibrium of secondary balanced unit.

The channel for satellite mobile communication terminal that the embodiment of the present invention provides is estimated and equal The method and device of weighing apparatus, it is possible to by the result of Viterbi decoding is encoded successively, hands over Knit, modulate, and carry out secondary letter with modulation symbol sequence as the known symbol docking collection of letters number Road is estimated, the result then estimated according to two secondary channels, and the docking collection of letters number carries out secondary equilibrium, And export the result after secondary equilibrium, with prior art, use the training sequence received Row y, docking collection of letters X carry out channel estimation, and the result estimating channel is carried out Equilibrium, owing to the training sequence y received is shorter, so that channel is estimated inaccurate Scheme compare, channel is estimated by secondary and equalizes by it so that shorter instruction The channel practicing sequences y is estimated more accurately, thus substantially increases the performance of adaptive equalization.

Accompanying drawing explanation

Fig. 1 shows the method flow that a kind of channel for satellite mobile communication terminal is estimated Figure；

Fig. 2 shows the method flow that a kind of channel for satellite mobile communication terminal is estimated Figure；

Fig. 3 shows the method flow that a kind of channel for satellite mobile communication terminal is estimated Figure；

Fig. 4 shows the method flow that a kind of channel for satellite mobile communication terminal is estimated Figure；

Fig. 5 shows the method flow that a kind of channel for satellite mobile communication terminal is estimated Figure；

Fig. 6 shows the method flow that a kind of channel for satellite mobile communication terminal is estimated Figure；

Fig. 7 shows the method flow diagram of a kind of equilibrium for satellite mobile communication terminal；

Fig. 8 shows the method flow diagram of a kind of equilibrium for satellite mobile communication terminal；

Fig. 9 shows the method flow diagram of a kind of equilibrium for satellite mobile communication terminal；

Figure 10 shows the method flow diagram using the output of MVA equalizer to receive signal；

MVA when Figure 11 shows a length of L=2 of disperse of satellite channel implements Process；

Figure 12 shows the method flow diagram of a kind of equilibrium for satellite mobile communication terminal；

Figure 13 shows the method flow diagram of a kind of equilibrium for satellite mobile communication terminal；

Figure 14 shows the method flow diagram using the soft output of VALPP algorithm to receive signal；

Figure 15 shows the method flow diagram of a kind of equilibrium for satellite mobile communication terminal；

Figure 16 shows the device of a kind of channel estimation for satellite mobile communication terminal Structural representation；

Figure 17 shows the structure of the device of a kind of equilibrium for satellite mobile communication terminal Schematic diagram；

Figure 18 shows the structure of the device of a kind of equilibrium for satellite mobile communication terminal Schematic diagram.

Detailed description of the invention

Below by specific embodiment and combine accompanying drawing and the present invention is done further in detail Describe.

Embodiments provide what a kind of channel for satellite mobile communication terminal was estimated Method, as it is shown in figure 1, include: the docking collection of letters number carries out channel estimation, utilizes channel to estimate The result of meter, the docking collection of letters number equalizes, and the result of equilibrium is demodulated successively, is solved Interweave and Viterbi decoding, export Viterbi decoding result, it is characterised in that the method is entered One step includes:

101, Viterbi decoding result is encoded, obtain the bit sequence of coding；

102, the bit sequence of coding is interleaved, obtains the bit sequence interweaved；

103, the bit sequence interweaved is modulated, obtains modulation symbol sequence；

104, again carry out channel with modulation symbol sequence as the known symbol docking collection of letters number to estimate Meter, exports the result that two secondary channels are estimated.

The side that the channel for satellite mobile communication terminal that the embodiment of the present invention provides is estimated Method and device, it is possible to by the result of Viterbi decoding is encoded successively, interweaves, adjusts System, and carry out two secondary channel estimations with modulation symbol sequence as the known symbol docking collection of letters number, Then the result estimated according to two secondary channels, the docking collection of letters number carries out secondary equilibrium, and exports Result after secondary equilibrium, with prior art, uses the training sequence y received, right Receive signal X and carry out channel estimation, and the result estimating channel equalizes, by It is shorter in the training sequence y received, so that channel estimates inaccurate scheme phase Ratio, channel is estimated by secondary and equalizes by it so that shorter training sequence y's Channel is estimated more accurate, thus substantially increases the performance of adaptive equalization.

Further, as in figure 2 it is shown, the embodiment of the present invention is docked the Viterbi of the collection of letters number Decoding result encodes, and specifically includes:

201, use convolutional code that the output result of Viterbi decoding is carried out chnnel coding, obtain The bit sequence of coding；

202, the bit sequence of coding is interleaved, obtains the bit sequence interweaved；

203, the bit sequence interweaved is modulated, obtains modulation symbol sequence；

204, again carry out channel with modulation symbol sequence as the known symbol docking collection of letters number to estimate Meter, exports the result that two secondary channels are estimated.

Wherein, it is preferred to use the output result of Viterbi decoding is carried out by 1/2 rate convolutional code Coding, it would however also be possible to employ 1/3 rate convolutional code and 1/4 rate convolutional code are to Viterbi decoding Output result encode.

Further, as it is shown on figure 3, bit sequence to described coding in the embodiment of the present invention Row are interleaved, and specifically include:

301, Viterbi decoding result is encoded, obtain the bit sequence of coding；

302, the bit sequence of coding is carried out block interleaving, obtain the bit sequence interweaved；

303, the bit sequence interweaved is modulated, obtains modulation symbol sequence；

304, again carry out channel with modulation symbol sequence as the known symbol docking collection of letters number to estimate Meter, exports the result that two secondary channels are estimated.

Concrete, it is also possible to interleaving modes such as intertextures between random interleaving, row.

Further, as shown in Figure 4, bit sequence to described intertexture in the embodiment of the present invention Row are modulated, and specifically include:

401, Viterbi decoding result is encoded, obtain the bit sequence of coding；

402, the bit sequence of coding is interleaved, obtains the bit sequence interweaved；

403, QPSK (Quadrature Phase Shift Keying, quaternary phase shift key are used Control signal) bit sequence interweaved is modulated, obtain modulation symbol sequence；

404, again carry out channel with modulation symbol sequence as the known symbol docking collection of letters number to estimate Meter, exports the result that two secondary channels are estimated.

Concrete, it would however also be possible to employ BPSK (Binary Phase Shift Keying, phase shift key Control), ASK (Amplitude Shift Keying, move keying modulation), FSK (Frequency-shift keying, shift keying modulation), and GFSK (Gauss Frequency Shift Keying, Gaussian Frequency Shift Keying) etc. the modulation system bit sequence to interweaving Row are modulated.Concrete, above-mentioned modulation system is all technological means commonly used in the trade, this This is not illustrated by inventive embodiments.

Further, as it is shown in figure 5, again carry out channel and estimate to include:

501, Viterbi decoding result is encoded, obtain the bit sequence of coding；

502, the bit sequence of coding is interleaved, obtains the bit sequence interweaved；

503, the bit sequence interweaved is modulated, obtains modulation symbol sequence；

504, minimum variance estimate LS is used, with modulation symbol sequence as known symbol pair Receive signal and carry out two secondary channel estimations, export the result that two secondary channels are estimated.

Concrete, use LS to carry out channel estimation, it is simply that to make mean square deviation minimum, i.e. following formula Minimum:

$\mathrm{\ϵ}=E\left\{(\hat{h}-h){(\hat{h}-h)}^H\right\}$

Wherein subscript H represents conjugate transpose.

If x is for sending symbol sebolic addressing, h is actual channel impulse response, and w is that channel is white Noise, y for receiving symbol sebolic addressing, then has:

Y=x h+w

The LS of h estimates to be:

$\hat{h}={\left(x^{H}x\right)}^{-1}{x}^{H}y$

Concrete, it is possible to use the sequences y and the locally known training sequence that receive complete Channel is estimated.For GMR-1 system, if there is the unique of kilo byte the centre of each burst Word, they are that oneself knows for terminal, and have good autocorrelation performance.Cause This, the unique word in burst can be used to as locally known training sequence.Terminal is often received To a burst, it is possible to utilize the Unique word and locally known training sequence received Do relevant, obtain the impulse response of channel.

Channel estimate can first pass through receive sequences y carry out to known array X relevant transport Calculate, the most again the value obtained is usedIt is filtered.According to different channel rank Number, the dimension of X is the most different.If channel exponent number is N, a length of M of training sequence, then Have

$\underset{\‾}{\underset{\‾}{\hat{X}}}=\left[\begin{array}{cccc}x(N-1),& x(N-2),& \mathrm{...},& x\left(0\right)\\ x\left(N\right),& x(N-1),& \mathrm{...},& x\left(1\right)\\ \mathrm{...}& \mathrm{...}& & \mathrm{...}\\ x\left(M\right),& x(M-1),& \mathrm{...},& x(M-N+1)\end{array}\right]$

Wherein, x (0)～x (N) is training sequence.

It should be noted that MMSE (Minimum Mean Square can also be used Error, Minimum Mean Squared Error estimation), with modulation symbol sequence as known symbol to reception Signal carries out two secondary channel estimations, exports the result that two secondary channels are estimated.

It should be noted that combination in any and the technical scheme that formed in above-mentioned optimal way, Can be embodiments of the invention, such as shown in Fig. 6.

601, use convolutional code that the output result of Viterbi decoding is carried out chnnel coding, obtain The bit sequence of coding；

602, the bit sequence of coding is carried out block interleaving, obtain the bit sequence interweaved；

603, use QPSK that the bit sequence interweaved is modulated, obtain modulation symbol Sequence；

604, use LS, carry out as the known symbol docking collection of letters number with modulation symbol sequence Two secondary channels are estimated, export the result that two secondary channels are estimated.

Embodiments provide the side of a kind of equilibrium for satellite mobile communication terminal Method, as it is shown in fig. 7, comprises:

701, the result that two secondary channels obtained according to above-mentioned channel estimation methods are estimated, docking The collection of letters number equalizes again；

702, the result after the equilibrium of output secondary.

The side of the channel equalization for satellite mobile communication terminal that the embodiment of the present invention provides Method, it is possible to by the result of Viterbi decoding is encoded successively, interweaves, modulates, and Two secondary channel estimations are carried out, then as the known symbol docking collection of letters number with modulation symbol sequence The result estimated according to two secondary channels, the docking collection of letters number carries out secondary equilibrium, and exports secondary Result after equilibrium, with prior art, uses the training sequence y received, to reception Signal X carries out channel estimation, and the result estimating channel equalizes, owing to connecing The training sequence y received is shorter, so that channel estimates that inaccurate scheme is compared, Channel is estimated by secondary and equalizes by it so that the channel of shorter training sequence y It is more accurate to estimate, thus substantially increases the performance of adaptive equalization.

Further, as shown in Figure 8, again equalize, including:

801, MLSE (Maximum likelihood sequence estimate, maximum are used Likelihood sequence estimation), the docking collection of letters number equalizes again.

802, the result after the equilibrium of output secondary.

Concrete, it is possible to use the method docking collection of letters number of decision-feedback equalizes again.

Further, as it is shown in figure 9, use the MLSE docking collection of letters number again to equalize, Including:

901, MVA (melioratio VITERB arithmetic, the Viterbi of improvement are used Algorithm), the docking collection of letters number equalizes again.

902, the result after the equilibrium of output secondary.

Concrete, as shown in Figure 10: using MLSE to equalize, MLSE uses MVA Realize.Concrete, including: channel estimating unit 1001, matched filtering device 1002, phase Close device 1003 and MVA processor 1004.

Concrete, MVA equalizer is applicable to the linear unreasonably by having additive Gaussian noise Think the signal of bandwidth efficient channel.If the overall response of channel h (t) represents, then the letter received Number can be expressed as:

$y\left(t\right)=\underset{k}{\Σ}{I}_{k}h(t-kT)+w\left(t\right)$

W (t) is additive white Gaussian noise.Wherein, w (t) includes modulated filter, channel rings Should, launch and receiving filter impact all-pass system whole recovering pulse response.Coupling filter Ripple device 1002 is followed by a sampler working in character rate 1/T, then uses MVA Equalizer carries out sequence estimation, obtains estimated value

Concrete, the output of matched filtering device 1002 can be expressed as:

$\begin{array}{c}{r}_n=r\left(nT\right)=\[I_n\⊗h\left(n\right)+w\left(n\right)\]\⊗h^{*}(-n)\\ =I_n\⊗\left(h\right(n)\⊗h^{*}(-n\left)\right)+w\left(n\right)\⊗h^{*}(-n)\\ =I_n\⊗x\left(n\right)+v\left(n\right)\\ =\underset{k}{\Σ}{I}_k{x}_{n-k}+v\left(n\right)\end{array}$

Wherein { x (n) } is the matched filtering device 1002 response to { h (n) }:

$x_n=\underset{k}{\Σ}{h}_k^{*}{h}_{k+n}$

Can be seen that { x (n) } is also the auto-correlation of channel response { h (n) }.

{ v (n) } is the response after channel additive white Gaussian noise passes through matched filtering device 1002, It is expressed as:

$v_n=\underset{k}{\Σ}{w}_k{h}_{k-n}^{*}$

Actual realization when, matched filtering device 1002 is channel estimating unit 1001 The channel estimation value obtainedFrom the point of view of the process that channel is estimated,Also it is to include tune The overall response function of wave filter processed, channel response, transmitting and receiving filter etc..

Wherein, MVA particularly as follows:

When transmission sequence is { I_n, when observation interval is the longest, maximum likelihood function p[y(t)∈M|{I_n] logarithm and following formula in J₁({I_n) be directly proportional,

$\begin{array}{c}{J}_1\left(\right\{I_n\left\}\right)=-{\∫}_{-\mathrm{\∞}}^{\mathrm{\∞}}{|y\left(t\right)-\underset{n}{\Σ}{I}_{n}h(t-nT)|}^{2}dt\\ =-{\∫}_{-\mathrm{\∞}}^{\mathrm{\∞}}{\left|y\left(t\right)\right|}^{2}dt+2\mathrm{Re}\underset{n}{\Σ}\[{I^{*}}_n{\∫}_{-\mathrm{\∞}}^{\mathrm{\∞}}y\left(t\right)h^{*}(t-nT)dt\]-\underset{n}{\Σ}\underset{m}{\Σ}{I}_n^{*}{I}_m{\∫}_{-\mathrm{\∞}}^{\mathrm{\∞}}{h}^{*}(t-nT)h(t-mT)dt.\end{array}$

Wherein | y (t) |²Integration and { I_nUnrelated, it is convenient to omit, and by { r_nAnd { x_nIn substitution Formula has:

$J_1\left(\right\{I_n\left\}\right)=2\mathrm{Re}\underset{n}{\Σ}\left({I^{*}}_n{r}_n\right)-\underset{n}{\Σ}\underset{m}{\Σ}{I}_n^{*}{I}_m{x}_{n-m}.$

{r_nIt is the output of matched filtering device, { x_nIt is channel autocorroelation function, channel can be passed through Estimated value is tried to achieve.Visible sequence { r_nContain all relevant { I_nRelevant information, be therefore {I_nAbundant statistics, travel through all possible { I_nInput combination, make the sequence that tolerance is maximum It is exactly possible maximum sequence to occur, therefore by { r_nLinear process just can complete right Send symbol { I_nEstimation.

But it is the longest generally to send sequence, calculates all possible transmission combined sequence J₁({I_n), the amount of calculation selecting the sequence corresponding to maximum is the biggest, from realizing coming up Say it is impossible, it is therefore desirable to find a kind of method of Dynamic Recurrent to realize, i.e. use The VITERBI algorithm of deconvolution completes { I_nSearch.

This search procedure can be regarded as the state estimation of Discrete Time Finite status system and asks Topic, therefore can be by the linear filter being viewed as having L+1 tap of channel equivalence, letter The a length of L of road disperse, i.e. channel output at any one time is by L currently and before New incoming symbol is determined.

At moment k, state vector is: S_k={ I_k-1,I_k-2,....,I_k-L}

If glossary of symbols dimension is M, then system has M^LIndividual state.Therefore this channel is permissible Equally with there being M^LThe grid chart of individual state describes.Due to sequence { I_kAnd { S_kReflect one by one Penetrating, maximum-likelihood sequence estimation also may be defined as search sequence { S_kSo that J ({ S_k) maximum. Each state in each moment may be shifted by some in previous moment M state, It is likely to transfer to some of subsequent time state equally.In grid chart, adjacent moment State be referred to as branch, branch end to end composition transfer path.Each branch has oneself Measure, path tolerance for composition path each branch tolerance and, measure the biggest, point The probability that branch path occurs is bigger.Having the path that maximum measures is i.e. most preferably estimating of sequence Meter.

FormulaAlgorithm can Recursive Implementation according to the following formula

$\begin{array}{c}{J}_k\left(S_k\right)=\max \{J_{k-1}\left(S_{k-1}\right)+\mathrm{Re}\[I_k^{*}(2r_k-x_0{I}_k-2\underset{m=1}{\overset{L}{\Σ}}{x}_m{I}_{k-m})\]\}\\ =\max \{J_{k-1}\left(S_{k-1}\right)+B_k(S_k;S_{k-1})\}\end{array}---1.1$

$B_k(S_k;S_{k-1})=2\mathrm{Re}\[I_k^{*}(r_k-\underset{m=1}{\overset{L}{\Σ}}{x}_m{I}_{k-m})\]---1.2$

This completes the derivation of branch metric in algorithm.When specifically calculating, we are also Eliminate coefficient 2, so can reduce the multiplying of each branch metric.

Concrete, as shown in figure 11, it is assumed that L is the length of equalizer, it is contemplated that satellite The MVA that the characteristic of channel is introduced here as a example by L=2 implements process.This In simple in order to illustrate, it is assumed that assemble of symbol be two-dimentional, assemble of symbol be 1 ,-1}, when During L=2, sign condition is as shown in table 1:

Table 1

Realization is divided into two processes of forward and backward:

Forward process: in the frame structure of normal burst, protection bit and tail bit ordinary circumstance Being 0, such original state can confirm that as S1, from original state, based on formula 1.2 Engraving when calculating each, the branch metric arriving next state Sj is m1, m2, and corresponding Tolerance Mk-1 of two survivor paths, 2j, Mk-1,2j+1, both be separately summed, Selecting the greater from two accumulated values, the survival as this state is measured, i.e. Mk, J=max (Mk-1,2j+m1, Mk-1,2j+1+m2), this path is referred to as survivor path, right The symbol sebolic addressing answered is referred to as survivor sequence, and another paths is referred to as contended path.Local with one Opening two-dimensional table and be saved in the survivor path of each moment each state corresponding, contended path exists It is deleted after having calculated.Along with constantly carrying out of forward process, generate this form.Above Process can be with " add one ratio one choosing ".

Reverse procedure: in the L moment, we obtain the survivor path that 2L-1 is different, it Corresponding to maximum in is exactly Maximum likelihood sequence, according to survivor path form forward Backtracking, it is possible to obtain an estimate symbol

Further, as shown in figure 12, the result after the equilibrium of output secondary includes:

1201, the result estimated according to above-mentioned two secondary channels, the docking collection of letters number is carried out all again Weighing apparatus.

1202, use the mode of soft output, the result after output secondary equilibrium, be used for improving The decoding performance of outer level, thus improve the performance of whole system.

Concrete, in satellite mobile communication terminal, there is the Viterbi decoding of two-stage cascade, Wherein the equalizing for MLSE of internal Viterbi decoding, outside being used for carries out forward error correction. Such level is associated with two shortcomings, and one is: if interior level exists continuous print burst error, meeting Have a strong impact on the performance of outer level, and satellite channel under the conditions of, this burst error is not Evitable；Two is the information of the Viterbi decoding offer of the external level of hard decision result of interior level Measure insufficient, make the performance of outer level be affected.For the first point, add between two-stage Interleaving block can make continuous mistake become single error, such that it is able to improve outer level Viterbi The performance of decoding.For second point, if interior level output soft decision information, then could be one Determining to improve in degree the performance of outer level, so-called soft output refers to that equalizer not only exports judgement symbol Number sequence, gives the reliability information on this symbol, so can improve the decoding of outer level Performance, thus improve the performance of whole system.Wherein, it would however also be possible to employ the mode of hard output.

Further, as shown in figure 13, the mode of soft output, output secondary equilibrium are used After result, specifically include:

1301, the result estimated according to two secondary channels, the docking collection of letters number equalizes again.

1302, use VALPP (viterbi algorithm likelyhood post proccessing, VA algorithm with likelihood preprocessor), the result after output secondary equilibrium, outside being used for improving The decoding performance of level, thus improve the performance of whole system.

Sequence judgement and reliability letter can separately be carried out by VALPP.VALPP can be general Include for: first (the most arbitrarily decode with VA (viterbi algorithm, viterbi algorithm) Device/demodulator) produce hard decision sequence, by this judgement sequence and reliability information need to be produced In code element and the produced sequence sets of some code element neighbouring upset is respectively as likelihood function The difference conduct of input, the likelihood value taking judgement sequence and the upset sequence with maximum likelihood value Reliability information in this code element.

VALPP structure as shown in figure 14, including matched filtering device 1002, MVA process Device 1004, outer level Viterbi decoding 1403 and likelihood preprocessor (LPP) 1404；

Concrete, the proposition of VALPP is mainly based upon following 2 reasons: first, optimum Sequence is the most only by some state, and this optimal sequence is one section of time delay After can be obtained by.So, if introduce time delay when calculating soft output, in judgement sequence Under the conditions of acquired, reliability information only need to be carried out in judgement code element.So VALPP has higher efficiency..

The basic step that VALPP realizes is as follows: estimate maximum likelihood sequence first with MVA RowThen the calculating of authentic communication is carried out.Use formula 2.1 calculates

$J\left(\right\{{\hat{I}}_k\left\}\right)=2\mathrm{Re}\underset{k}{\Σ}\left({{\hat{I}}_k}^{*}{r}_k\right)-\underset{k}{\Σ}\underset{m}{\Σ}{{\hat{I}}_k}^{*}{\hat{I}}_m{x}_{k-m}---2.1$

At each moment k, in window (k-D, k+D) interior turnover codes unit, find and replace sequence RowMeet in all replaceable sequences it and there is measuring of maximum(also use Formula 2.1 calculates), calculate the authentic communication in this moment

As D=0, the most only overturning the code element in k moment, authentic communication is reduced to:

$L\left(k\right)=4\mathrm{Re}\left(\widehat{I_k^{*}}\right(y_k-\underset{m\≠0}{\overset{4}{\underset{m=-4}{\Σ}}}{x}_m\widehat{I_{k-m}}\left)\right)--2.2$

I.e. need not calculate the measurement value of whole sequence, and in only needing to utilize (k-4, k+4) Sequence by the calculating of equation 2 above .2, i.e. can obtain engraving when calculating k the reliability of code element Information.

By above-mentioned analysis, it has been found that after this band the algorithm structure of level processor due to The output module of VA module and reliability information can separate so that this algorithm can obtain To promote.

Then it is soft demodulated, then according to block interleaving to the signal after second time equilibrium Structure, deinterleaves accordingly the Soft Inform ation after demodulation and finally carries out Viterbi decoding, Thus carried out estimating accurately to channel.

It should be noted that combination in any and the technical scheme that formed in above-mentioned optimal way, Can be embodiments of the invention, such as shown in Figure 15.

1501, using MVA, the docking collection of letters number equalizes again.

1502, VALPP is used, the result after output secondary equilibrium.

Embodiments provide a kind of dress estimated for satellite mobile communication terminal channel Put, as shown in figure 16, including: 1605, balanced unit of a channel estimating unit 1606, decoding unit 1607；Wherein

Channel estimating unit 1605, is used for docking the collection of letters number and carries out channel estimation, obtain Channel estimation results；

Balanced unit 1606, for utilizing channel estimating unit 1605 to obtain Channel estimation results, the docking collection of letters number equalizes, and is equalized result；

Decoding unit 1607, the result of the equilibrium for balanced unit 1606 is obtained It is demodulated successively, deinterleaves and Viterbi decoding, export Viterbi decoding result；This dress Put and also include: coding unit 1601, interleave unit 1602, modulating unit 1603 and two Secondary channel estimation unit 1604, wherein: as shown in figure 17,

Coding unit 1601, is carried out for docking the output result of the Viterbi decoding of the collection of letters number Coding, obtains the bit sequence of coding.

Interleave unit 1602, enters for the bit sequence obtaining coding unit 1601 coding Row interweaves, and obtains the bit sequence interweaved.

Modulating unit 1603, enters for the bit sequence obtained that interweaves interleave unit 1602 Row modulation, obtains modulation symbol sequence.

Secondary channel estimating unit 1604, obtains symbol sebolic addressing with modulating unit 1603 modulation Carry out two secondary channel estimations as the known symbol docking collection of letters number, export what two secondary channels were estimated Result.

The dress that the channel for satellite mobile communication terminal that the embodiment of the present invention provides is estimated Put, it is possible to by the result of Viterbi decoding is encoded successively, interweaves, modulates, and Two secondary channel estimations are carried out, then as the known symbol docking collection of letters number with modulation symbol sequence The result estimated according to two secondary channels, the docking collection of letters number carries out secondary equilibrium, and exports secondary Result after equilibrium, with prior art, uses the training sequence y received, to reception Signal X carries out channel estimation, and the result estimating channel equalizes, owing to connecing The training sequence y received is shorter, so that channel estimates that inaccurate scheme is compared, Channel is estimated by secondary and equalizes by it so that the channel of shorter training sequence y It is more accurate to estimate, thus substantially increases the performance of adaptive equalization.

Embodiments provide the dress of a kind of equilibrium for satellite mobile communication terminal Put, as shown in figure 18, including: channel estimating apparatus, it is used for exporting described two secondary channels and estimates The result of meter and secondary balanced unit 1701 and output unit 1702, wherein

Secondary balanced unit 1701, for the result estimated according to two secondary channels, docking is collected mail Number carry out secondary equilibrium.

Output unit 1702, the result after exporting secondary balanced unit 1701 equilibrium.

The dress of the channel equalization for satellite mobile communication terminal that the embodiment of the present invention provides Put, it is possible to by the result of Viterbi decoding is encoded successively, interweaves, modulates, and Two secondary channel estimations are carried out, then as the known symbol docking collection of letters number with modulation symbol sequence The result estimated according to two secondary channels, the docking collection of letters number carries out secondary equilibrium, and exports secondary Result after equilibrium, with prior art, uses the training sequence y received, to reception Signal X carries out channel estimation, and the result estimating channel equalizes, owing to connecing The training sequence y received is shorter, so that channel estimates that inaccurate scheme is compared, Channel is estimated by secondary and equalizes by it so that the channel of shorter training sequence y It is more accurate to estimate, thus substantially increases the performance of adaptive equalization.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, For a person skilled in the art, the present invention can have various modifications and variations.All Within the spirit and principles in the present invention, any modification, equivalent substitution and improvement etc. made, Should be included within the scope of the present invention.

Claims (9)

1. the method estimated for the channel of satellite mobile communication terminal, including: right Receive signal and carry out channel estimation, utilize the result that channel is estimated, described reception signal is entered Row equilibrium, is demodulated successively the result of equilibrium, deinterleaves and Viterbi decoding, output Viterbi decoding result, it is characterised in that the method farther includes:

Described Viterbi decoding result is encoded, obtains the bit sequence of coding；

The bit sequence of described coding is interleaved, obtains the bit sequence interweaved；

The bit sequence of described intertexture is modulated, obtains modulation symbol sequence；

As known symbol, described reception signal is carried out channel again with modulation symbol sequence to estimate Meter, exports the result that two secondary channels are estimated；

Wherein, described coding includes: use convolutional code to carry out described Viterbi decoding result Chnnel coding；

Described intertexture includes: the bit sequence of described coding is carried out block interleaving；

Described modulation includes: use the QPSK signal QPSK ratio to described intertexture Special sequence is modulated.

Method the most according to claim 1, it is characterised in that described again carry out Channel is estimated to include:

Use minimum variance estimate LS, described modulation symbol sequence is carried out two secondary channels and estimates Meter.

3. the method for the equilibrium of satellite mobile communication terminal, it is characterised in that Including:

Obtain according to the channel estimation methods described in claim any one of claim 1～2 Two secondary channels estimate result, described reception signal is equalized again；

Result after output secondary equilibrium.

Method the most according to claim 3, it is characterised in that described again carry out Equilibrium includes:

Use Maximum likelihood sequence valuation MLSE, described reception signal is equalized again.

Method the most according to claim 4, it is characterised in that described employing MLSE Described reception signal is equalized again, including:

Use the viterbi algorithm MVA improved, described reception signal is equalized again.

Method the most according to claim 3, it is characterised in that described output secondary Result after equilibrium, including:

Use the mode of soft output, export the result after the equilibrium of described secondary.

Method the most according to claim 6, it is characterised in that described employing is soft defeated The mode gone out, exports the result after the equilibrium of described secondary, specifically includes:

Use the VA algorithm VALPP of band likelihood preprocessor, after exporting the equilibrium of described secondary Result.

8. the device estimated for the channel of satellite mobile communication terminal, including:

Channel estimating unit, is used for docking the collection of letters number and carries out channel estimation, obtain channel Estimated result；

Balanced unit, for the described letter utilizing a described channel estimating unit to obtain Road estimated result, equalizes described reception signal, is equalized result；

Decoding unit, for depending on the result of the described equilibrium that a described balanced unit obtains Secondary it is demodulated, deinterleaves and Viterbi decoding, export Viterbi decoding result；

It is characterized in that, this device also includes:

Coding unit, for encoding the output result of Viterbi decoding, is encoded Bit sequence；Described coding includes: use convolutional code to enter described Viterbi decoding result Row chnnel coding；

Interleave unit, is interleaved for the bit sequence obtaining described coding unit coding, Obtain the bit sequence interweaved；Described intertexture includes: carry out the bit sequence of described coding Block interleaving；

Modulating unit, is modulated for the bit sequence obtained that interweaves described interleave unit, Obtain modulation symbol sequence；Described modulation includes: use QPSK signal QPSK The bit sequence of described intertexture is modulated；

Secondary channel estimating unit, with modulation symbol sequence as known symbol to described reception Signal carries out two secondary channel estimations, exports the result that two secondary channels are estimated.

9. the device for the equilibrium of satellite mobile communication terminal, it is characterised in that Including:

Channel estimating apparatus described in claim 8, is used for exporting described two secondary channels and estimates Result；

Secondary balanced unit, for the result estimated according to described two secondary channels, docking is collected mail Number carry out secondary equilibrium；

Output unit, the result after exporting the equilibrium of described secondary balanced unit.