CN101834618B - Turbo decoding method and turbo decoder - Google Patents
Turbo decoding method and turbo decoder Download PDFInfo
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Abstract
The invention discloses a Turbo decoding method and a Turbo decoder for encoded signals with same initial states and final states. The Turbo decoding method comprises the following steps of: carrying out Turbo decoding cyclic iterative operation on encoded signals until an iterative terminal condition is satisfied to generate decoded signals, wherein carrying out forward recursive operation and backward recursive operation from initial forward state measurement (initial FSM) and initial backward state measurement (initial BSM) in each iterative operation process to obtain final FSM and final BSM; and setting the initial FSM and the initial BSM of the current iteration based on the final FSM and the final BSM obtained in the last recursive operation, wherein the initial FSM and the initial BSM are set into predetermined state measurement in the first recursive operation. According to the invention, the initial FSM and the initial BSM are simply determined in each recursive operation without introducing extra operation; thereby the Turbo decoding method and the Turbo decoder are beneficial to carrying out Turbo decoding.
Description
Technical field
Present invention relates in general to code signal is carried out method and the Turbo decoder of Turbo decoding.More especially, the present invention relates to the code signal with identical initial condition and end-state is carried out method and the Turbo decoder of Turbo decoding.
Background technology
Up to the present, wireless communication system has obtained swift and violent development.Original second generation mobile communication system, be global mobile communication (GSM) system constantly to technology evolution such as GPRS (GPRS), enhanced data rates for gsm evolution (EDGE), improved significantly the data transmission capabilities of system.Have more 3-G (Generation Three mobile communication system), the also one after another deployment in the scope of many countries and regions, the whole world such as the technology such as Wideband Code Division Multiple Access (WCDMA) (WCDMA), CDMA2000 of high transfer rate, begin to put it into commercial operation.In the cellular telecommunication art development, some other wireless access technology, for example WLAN (wireless local area network) (WLAN) and micro-wave access to global intercommunication (WiMAX) technology have also had fast development.In addition, strengthening projects such as (3GPP LTE+) towards the IEEE 802.16m technology of the 4th Generation Mobile Communication System and third generation partner program evolution technology (3GPP LTE), third generation partner program evolution technology has also begun to start and has entered development.
The Turbo decoder is an important devices of the physical layer of above-mentioned each communication system.In data communication service, the Turbo coding/decoding is most important channel coding/decoding method.The principle of Turbo encoder is relative with implementation method fixing, and the performance of Turbo decoder then can directly affect the performance of receiver.Turbo code is proposed 1993 by people such as C.Berrou the earliest.Wherein, realize the coding of large constraint length having the characteristic near random coded by the pseudo random interleaving of component code, and by adopting iterative decoding, can obtain the medium codec complexity, the error rate remains on the 1e-5 order of magnitude, thereby has approached shannon limit.Show through various researchs and simulation result, Turbo code is not only being resisted superior performance aspect the additive Gaussian noise, and have very strong anti-fading, an antijamming capability, its error-correcting performance is near shannon limit, this is so that Turbo code has in the communication system of reality very widely uses, wherein 3-G (Generation Three mobile communication system), such as International Mobile Telecommunication 2000 (IMT-2000) and IEEE 802.16e system all with Turbo code as one of standard channel of its transmitting high speed data.
All the time, in the process of Turbo coding, all initial condition and the end-state with encoder is preset as a certain known value, such as initial condition or end-state all are made as 0 state, is beneficial to the decoding of Turbo.A shortcoming of this way is must add the tail bit at the afterbody of information bit, with the control end-state.The adding of tail bit has reduced the spectrum efficiency of system.About the Turbo coding/decoding detailed process can (Wiley-IEEE Press publishes in September, 2002 referring to " the Turbo Coding; Turbo Equalisation and Space-TimeCoding for Transmission over Fading Channels " that for example shown by Lajos Ha and B.L.Yeap, ISBN number: 978-0-470-84726-8), just no longer described in detail at this.
Add the tail bit for fear of the afterbody at information bit, in IEEE 802.16e standard, adopted the Turbo decoding scheme of duobinary system circular recursion system convolution (double-binary circular recursivesystematic convolutional, DBCRSC) coding.In this scheme, the initial condition of code signal and end-state equate, but are not pre-set value.Therefore, receiver needs at first to determine initial condition and end-state in the process of computing of decoding.For example, in the Turbo decoder and Turbo coding/decoding method that in U.S. Patent Application Publication US2008/0273631A1, proposes, in the each time interative computation process of carrying out the Turbo decoding, respectively some part of total code block (comprising payload piece and filling block) of the DBCRSC code signal that receives is carried out forward recursive and backward recursive, thereby calculate the forward state metric (FSM) of estimation and the backward state measurement (BSM) of estimating, then utilize respectively estimated FSM and BSM that the remainder of total code block is carried out forward recursive and backward recursive.That is to say, in the each time interative computation of Turbo decoding, all need in advance the part of receive data to be processed, calculate initial condition tolerance and the end-state tolerance of forward recursive and backward recursive.Yet such method is neither optimum solution has been brought again extra operand.
Therefore, in the each time interative computation process of Turbo decoding, how to utilize better initial condition and the end-state of code signal to equate this characteristic, determine each time initial condition tolerance and the end-state tolerance of interative computation with less operand, thereby be beneficial to the execution of Turbo decoding, remain one of problem demanding prompt solution.
Summary of the invention
Provided hereinafter about brief overview of the present invention, in order to basic comprehension about some aspect of the present invention is provided.Should be appreciated that this general introduction is not about exhaustive general introduction of the present invention.It is not that intention is determined key of the present invention or pith, neither be intended to limit scope of the present invention.Its purpose only is that the form of simplifying provides some concept, with this as the in greater detail preorder of discussing after a while.
In order to solve the problems referred to above of prior art, an object of the present invention is to provide a kind of method and Turbo decoder for the code signal with identical initial condition and end-state being carried out the Turbo decoding, its initial condition and end-state that takes full advantage of code signal equates this characteristic, and can obtain better performance by the decoding algorithm that makes along with interative computation in the situation of not introducing extra operand.
To achieve these goals, according to an aspect of the present invention, a kind of method for the code signal with identical initial condition and end-state being carried out the Turbo decoding is provided, it may further comprise the steps: described code signal is carried out the loop iteration computing of Turbo decoding, until satisfy stopping criterion for iteration, with the generating solution coded signal, wherein, in the each time interative computation process of Turbo decoding, carry out forward recursive computing and backward recursive computing from forward direction initial condition tolerance and backward initial condition tolerance respectively, obtain thus forward direction end-state tolerance and backward end-state tolerance, in the first time of Turbo decoding interative computation, forward direction initial condition tolerance and backward initial condition tolerance are set to predetermined state tolerance, and in the n+1 time interative computation of Turbo decoding, forward direction initial condition tolerance and backward initial condition tolerance are based on that the forward direction end-state tolerance that obtains in the n time interative computation and backward end-state are measured and setting, and wherein n is natural number.
According to another aspect of the present invention, a kind of Turbo decoder for the code signal with identical initial condition and end-state being carried out the Turbo decoding also is provided, it comprises: at least one decoder module, be used at least one component code of described code signal is carried out the loop iteration computing of Turbo decoding, until satisfy stopping criterion for iteration, with the generating solution coded signal, wherein in the each time interative computation process of Turbo decoding, carry out forward recursive computing and backward recursive computing from forward direction initial condition tolerance and the backward initial condition tolerance of described at least one component code respectively, obtain thus forward direction end-state tolerance and the backward end-state tolerance of described at least one component code, wherein, described Turbo decoder further comprises: at least one forward-backward algorithm initial condition setting device, be used for arranging forward direction initial condition tolerance and the backward initial condition tolerance of described at least one component code, and provide it to described at least one decoder module, wherein, in the first time of Turbo decoding interative computation, forward direction initial condition tolerance and the backward initial condition tolerance of described at least one component code are set to predetermined state tolerance, and in the n+1 time interative computation of Turbo decoding, forward direction end-state that the forward direction initial condition of described at least one component code tolerance and backward initial condition tolerance are based on described at least one component code that obtains in the n time interative computation is measured and backward end-state measures to arrange, and wherein n is natural number.
Wherein, described forward direction initial condition tolerance comprises probability or the logarithm probability likelihood ratio of each possibility initial condition of described code signal, and described backward initial condition tolerance comprises probability or the logarithm probability likelihood ratio of each possibility end-state of described code signal.
The invention has the advantages that, in Turbo coding/decoding method according to the present invention and Turbo decoder, taken into full account and utilized initial condition and the end-state of code signal to equate this characteristic, measure (also can referred to as final BSM) based on the forward direction end-state tolerance that in the upper once interative computation of Turbo decoding, obtains (also can referred to as final FSM) and backward end-state, be arranged on forward direction initial condition tolerance in the last time interative computation of Turbo decoding (also can referred to as initial FSM) and backward initial condition and measure (also can referred to as initial BSM), therefore do not need to carry out extra computing and obtain forward direction initial condition tolerance and backward initial condition tolerance, and along with the carrying out of the interative computation of Turbo decoding, the initial condition tolerance of forward recursive and backward recursive and the calculating of end-state tolerance are more and more accurate, thereby so that decoding algorithm can be obtained better performance.
By below in conjunction with the detailed description of accompanying drawing to most preferred embodiment of the present invention, these and other advantage of the present invention will be more obvious.
Description of drawings
The present invention can by with reference to hereinafter by reference to the accompanying drawings given description be better understood, wherein in institute's drawings attached, used same or analogous Reference numeral to represent identical or similar parts.Described accompanying drawing comprises in this manual and forms the part of this specification together with following detailed description, and is used for further illustrating the preferred embodiments of the present invention and explains principle and advantage of the present invention.In the accompanying drawings:
Fig. 1 shows the indicative flowchart that carries out the method for Turbo decoding according to the code signal to having identical initial condition and end-state of the embodiment of the invention;
Fig. 2 shows the schematic block diagram that carries out the Turbo decoder of Turbo decoding according to the code signal to having identical initial condition and end-state of the embodiment of the invention; And
Fig. 3 shows according to IEEE 802.16e standard, utilizes as shown in Figure 1 Turbo coding/decoding method and/or the performance curve that the signal of DBCRSC coding is carried out the Turbo decoding of Turbo decoder as shown in Figure 2.
It will be appreciated by those skilled in the art that in the accompanying drawing element only for simple and clear for the purpose of and illustrate, and not necessarily draw in proportion.For example, the size of some element may have been amplified with respect to other elements in the accompanying drawing, in order to help to improve the understanding to the embodiment of the invention.
Embodiment
In connection with accompanying drawing example embodiment of the present invention is described hereinafter.For clarity and conciseness, all features of actual execution mode are not described in specification.Yet, should understand, in the process of any this practical embodiments of exploitation, must make a lot of decisions specific to execution mode, in order to realize developer's objectives, for example, meet those restrictive conditions with system and traffic aided, and these restrictive conditions may change to some extent along with the difference of execution mode.In addition, might be very complicated and time-consuming although will also be appreciated that development, concerning the those skilled in the art that have benefited from present disclosure, this development only is routine task.
At this, what also need to illustrate a bit is, for fear of having blured the present invention because of unnecessary details, only show in the accompanying drawings with according to the closely-related device structure of the solution of the present invention and/or treatment step, and omitted other details little with relation of the present invention.
Fig. 1 shows and according to the embodiment of the invention code signal with identical initial condition and end-state (for example, the signal of DBCRSC coding) is carried out the indicative flowchart of the method 100 of Turbo decoding.
As shown in Figure 1, Turbo coding/decoding method 100 is initialized as 1 by the iterations i with the Turbo decoding in step S110 begins, and whether for the first time the interative computation of the Turbo decoding that then judgement will be carried out in step S120 interative computation.
If in step S120, determine to carry out the interative computation first time of Turbo decoding, then the processing of method 100 proceeds to step S130, with forward direction initial condition tolerance (namely therein, initial FSM) and backward initial condition tolerance (that is, initial BSM) be set to respectively predetermined state and measure.
In an example of Turbo coding/decoding method 100, described initial FSM comprises probability or the logarithm probability likelihood ratio of each possibility initial condition of described code signal, and described initial BSM comprises probability or the logarithm probability likelihood ratio of each possibility end-state of described code signal; And in the first time of Turbo decoding interative computation, described initial FSM and initial BSM are set up respectively as follows: probability or the logarithm probability likelihood ratio of each possibility initial condition of described code signal are set up equal, each of described code signal may end-state probability or logarithm probability likelihood ratio be set to equate, and all equal a certain predetermined value (for example 0).Wherein, described probability and logarithm probability likelihood ratio are one to one, and can mutually calculate.Yet, should be understood that principle of the present invention is not limited only to this.For example, in the first time of Turbo decoding interative computation, each that can code signal may initial condition and each may end-state probability or other arbitrary values that logarithm probability likelihood ratio is set to non-zero.
Next, as shown in Figure 1, in step S140, carry out forward recursive computing and backward recursive computing from forward direction initial condition tolerance and backward initial condition tolerance respectively, obtain thus the forward direction end-state tolerance of interative computation last time (namely, final FSM) and backward end-state tolerance (that is, finally BSM).At this, process in the process of forward recursive computing and backward recursive computing and the existing Turbo decoding is identical, for example, can be referring to " Turbo Coding; Turbo Equalisation and Space-Time Coding for Transmission over FadingChannels " of above mentioning etc., therefore, for specification for purpose of brevity, just no longer the detailed process of forward recursive computing and backward recursive computing has been described in detail at this.
Then, in step S150, will in step S140, obtain when the forward direction end-state tolerance of interative computation last time and after store to end-state tolerance so that in the next iteration computing.
Next, the handling process of method 100 proceeds to step S160, judges whether to satisfy predetermined stopping criterion for iteration.At this, described predetermined stopping criterion for iteration can be such as having reached predetermined iterations etc.Yet principle of the present invention is not limited only to this, and those skilled in the art can set stopping criterion for iteration fully according to actual needs.For example, under some specific occasion, also stopping criterion for iteration can be set as follows: each time interative computation result is carried out cyclic redundancy check (CRC) (namely, CRC check), if verification is passed through, then stop the interative computation process, and if verification is not passed through, then proceed next iteration, until reach predetermined iterations.
If in step S160, determine also not satisfy stopping criterion for iteration, then in step S170, iterations i added 1, namely, i=i+1, then handling process turns back to step S120, judges whether the current iteration that will carry out is the interative computation first time of Turbo decoding.
When determining that in step S120 the current interative computation that will carry out is not that first time of Turbo decoding is during interative computation, handling process proceeds to step S180, based on the forward direction end-state tolerance of storing, in upper once interative computation, obtain and rear to end-state tolerance, last time forward direction initial condition tolerance and the backward initial condition tolerance of interative computation are set.
For example, in an example of method 100, can with in upper once interative computation, obtain rear to end-state tolerance and forward direction end-state tolerance be set to respectively when the forward direction initial condition tolerance of interative computation last time with after measure to initial condition; Perhaps, also forward direction end-state tolerance and the backward end-state tolerance that obtains in the last interative computation can be set to respectively last time forward direction initial condition tolerance and the backward initial condition tolerance of interative computation.In this example, described forward direction initial condition tolerance can comprise probability or the logarithm probability likelihood ratio of each possibility initial condition of described code signal, and described backward initial condition tolerance can comprise probability or the logarithm probability likelihood ratio of each possibility end-state of described code signal, wherein, described probability and logarithm probability likelihood ratio are one to one, and can mutually calculate.
In another example of method 100, can in upper once interative computation, obtain rear to end-state tolerance and forward direction end-state tolerance be weighted summation and the state measurement that obtains be set to when the forward direction initial condition tolerance of interative computation last time with after measure to initial condition.
For example, suppose that described code signal is preset with four kinds of possible initial conditions and corresponding four kinds of possible end-state with it when being begun to encode by encoder, wherein, the logarithm probability likelihood ratio of four kinds of possible initial conditions is represented as respectively α
1, α
2, α
3, α
4, the logarithm probability likelihood ratio of four kinds of possible end-state is represented as respectively β
1, β
2, β
3, β
4, the forward direction end-state tolerance that obtains in upper once interative computation and rear tolerance to end-state are represented as respectively: { β
1, β
2, β
3, β
4, and { α
1, α
2, α
3, α
4, then can be according to equation γ
i=a
iα
i+ b
iβ
i(a wherein
iAnd b
iBe weight, i=1,2,3,4) described forward direction end-state tolerance and backward end-state tolerance are weighted summation, and with resulting state measurement { γ
1, γ
2, γ
3, γ
4The forward direction initial condition tolerance and the backward initial condition that are set to interative computation last time measure.Wherein, those skilled in the art can arrange different weight a as required
iAnd b
iFor example, under additive white Gaussian noise (AWGN) channel condition, can think that the confidence level of the forward direction end-state tolerance that obtains through recursive operation and backward end-state tolerance is equal, like this can be with a
iAnd b
iAll be set to 0.5.Certainly, also can they be set to other value as required.
In another example of method 100, can in upper once interative computation, obtain rear measure to be weighted to end-state tolerance and forward direction end-state multiply each other, and product carried out normalization, the state measurement that then obtains thus is set to that last time forward direction initial condition tolerance and the backward initial condition of interative computation are measured.
For example, suppose that described code signal is preset with four kinds of possible initial conditions and corresponding four kinds of possible end-state with it when being begun to encode by encoder, wherein, the probability of four kinds of possible initial conditions is represented as respectively α
1, α
2, α
3, α
4, the probability of four kinds of possible end-state is represented as β
1, β
2, β
3, β
4, the forward direction end-state tolerance that obtains in upper once interative computation and rear tolerance to end-state are represented as respectively: { β
1, β
2, β
3, β
4, and { α
1, α
2, α
3, α
4, then can be according to following equation computing mode tolerance { γ
1, γ
2, γ
3, γ
4}:
And with the state measurement { γ that calculates
1, γ
2, γ
3, γ
4The forward direction initial condition tolerance and the backward initial condition that are set to interative computation last time measure.Wherein, those skilled in the art can arrange different weight a as required
iAnd b
i, and i=1,2,3,4, j=1,2,3,4.
Refer again to Fig. 1, in step S180, be provided with when the forward direction initial condition tolerance of interative computation last time and after after initial condition tolerance, in step S140, carry out forward recursive and backward recursive, and repeat the processing of each step described above, thereby code signal is carried out the loop iteration computing of Turbo decoding, until determine to have satisfied stopping criterion for iteration in step S160, the handling process of method 100 just finishes in step S190, thereby finally can obtain decoded signal.
Fig. 2 shows the schematic block diagram that carries out the Turbo decoder 200 of Turbo decoding according to the code signal to having identical initial condition and end-state of the embodiment of the invention.In Turbo decoder 200 shown in Figure 2, can carry out the 1 described Turbo coding/decoding method with reference to figure.
As shown in Figure 2, Turbo decoder 200 comprises that at least one decoder module (there is shown two decoder module 210A and 210B, but principle of the present invention is not limited to this), be used at least one component code of described code signal is carried out the loop iteration computing of Turbo decoding, until satisfy stopping criterion for iteration, to generate the decoded signal of described component code.Wherein, in the each time interative computation process of Turbo decoding, carry out forward recursive computing and backward recursive computing from forward direction initial condition tolerance and the backward initial condition tolerance of described at least one component code respectively, obtain thus forward direction end-state tolerance and the backward end-state tolerance of described at least one component code.Wherein, described at least one decoder module is the soft soft soft decoder module that goes out that enters.
In Turbo decoder 200 as shown in Figure 2, decoder module 210A and 210B, sum unit 220A and 220B, interleaver 230, deinterleaver 240, the function of corresponding component identical with operating process (its detail can referring to for example " Turbo Coding; TurboEqualisation and Space-Time Coding for Transmission over FadingChannels " and U.S. Patent Application Publication US2008/0273631A1 etc.) in the function of hard decision unit 250 and deinterleaver 260 and specific operation process and the existing Turbo decoder, and these parts are not the focus places that the present invention pays close attention to, therefore, for specification for purpose of brevity, just no longer these parts have been specifically described at this.
As shown in Figure 2, different from existing Turbo decoder is, Turbo decoder 200 comprises that also at least one forward-backward algorithm initial condition setting device (there is shown two forward-backward algorithm initial condition setting device 270A and 270B, but principle of the present invention is not limited to this), for forward direction initial condition tolerance and the backward initial condition tolerance of each time at least one component code described in the interative computation that is arranged on the Turbo decoding, and provide it to described at least one decoder module.In the first time of Turbo decoding interative computation, described at least one forward-backward algorithm initial condition setting device can described at least one component code forward direction initial condition tolerance and backward initial condition tolerance be set to predetermined state and measure, and in the inferior interative computation of n+1 (wherein n is natural number) of Turbo decoding, described at least one forward-backward algorithm initial condition setting device can be based on the forward direction end-state of described at least one component code that obtains in the n time interative computation tolerance and rear to end-state tolerance, and forward direction initial condition tolerance and backward initial condition that described at least one component code is set are measured.In view of above measuring and be described how forward direction initial condition tolerance in the interative computation each time and backward initial condition are set with reference to flow chart shown in Figure 1, therefore, for fear of unnecessary repetition, described in detail with regard to the function to described at least one forward-backward algorithm initial condition setting device no longer at this.
Fig. 3 shows according to IEEE 802.16e standard, utilizes as shown in Figure 1 Turbo coding/decoding method and/or the performance curve that the signal of DBCRSC coding is carried out the Turbo decoding of Turbo decoder as shown in Figure 2.
In Fig. 3, altogether show 11 bunches of curves, wherein every cluster curve table has shown the decoding performance corresponding to a kind of modulation coding mode, and comprising 8 curves in every cluster curve, it has represented respectively the decoding performance in the first time to the of Turbo decoding eight interative computations from right to left.In Fig. 3, the corresponding modulating coded system that 11 bunches of Curves from left to right represent is respectively:
(1) QPSK (Quadrature Phase Shift Keying) modulation, 1/2 code check repeats coding 6 times;
(2) QPSK modulation, 1/2 code check repeats coding 4 times;
(3) QPSK modulation, 1/2 code check repeats coding 2 times;
(4) QPSK modulation, 1/2 code check, not repeated encoding;
(5) QPSK modulation, 3/4 code check, not repeated encoding;
(6) 16QAM (hexadecimal quadrature amplitude modulation) modulation, 1/2 code check, not repeated encoding;
(7) 16QAM modulation, 3/4 code check, not repeated encoding;
(8) 64QAM modulation (60 quaternary quadrature amplitude modulation), 1/2 code check, not repeated encoding;
(9) 64QAM modulation, 2/3 code check, not repeated encoding;
(10) 64QAM modulation, 3/4 code check, not repeated encoding;
(11) 64QAM modulation, 5/6 code check, not repeated encoding.
From decoding performance curve shown in Figure 3, be not difficult to find out, increase along with the interative computation number of times of Turbo decoding, BLER (Block Error Rate) reduces day by day in the identical situation of SINR (Signal to Interference plus Noise Ratio), perhaps SINR reduces day by day in the identical situation of BLER, that is to say, along with the carrying out of the interative computation of Turbo decoding, the Turbo decoding algorithm can be obtained better performance.
By above to finding out according to the Turbo coding/decoding method of the embodiment of the invention and the description of Turbo decoder, the initial condition and the end-state that have taken into full account code signal in the interative computation of Turbo decoding equate this characteristic, based on the forward direction end-state tolerance (final FSM) that in upper once interative computation, obtains and backward end-state tolerance (final BSM) last time forward direction initial condition tolerance (initial FSM) and the backward initial condition tolerance (initial BSM) of interative computation are set, do not need as in the prior art, to introduce extra operand and estimate initial FSM and initial BSM, and along with the carrying out of interative computation, the calculating of initial condition tolerance and end-state tolerance is more and more accurate, thereby so that decoding algorithm can be obtained better performance.
In addition, obviously, also can realize in the mode that is stored in the computer executable program in the various machine-readable storage mediums according to each operating process of said method of the present invention.
And, purpose of the present invention also can realize by following manner: the storage medium that will store above-mentioned executable program code offers system or equipment directly or indirectly, and the said procedure code is read and carried out to the computer in this system or equipment or CPU (CPU).At this moment, as long as this system or equipment have the function of executive program, then embodiments of the present invention are not limited to program, and this program also can be form arbitrarily, for example, the program carried out of target program, interpreter or the shell script that offers operating system etc.
Above-mentioned these machinable mediums include but not limited to: various memories and memory cell, semiconductor equipment, disk cell be light, magnetic and magneto optical disk for example, and other is suitable for the medium of the information of storing etc.
In addition, computer is by being connected to the corresponding website on the internet, and will download and be installed in the computer according to computer program code of the present invention, then carries out this program, also can realize the present invention.
At last, also need to prove, in this article, only be used for an entity or operation are made a distinction with another entity or operation such as relational terms left and right, first and second etc., and not necessarily require or hint and have the relation of any this reality or sequentially between these entities or the operation.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thereby not only comprise those key elements so that comprise process, method, article or the equipment of a series of key elements, but also comprise other key elements of clearly not listing, or also be included as the intrinsic key element of this process, method, article or equipment.Do not having in the situation of more restrictions, the key element that is limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment that comprises described key element and also have other identical element.
Although more than describe by reference to the accompanying drawings embodiments of the invention in detail, should be understood that execution mode described above just is used for explanation the present invention, and be not construed as limiting the invention.For a person skilled in the art, can make various changes and modifications above-mentioned execution mode and do not deviate from the spirit and scope of the invention.Therefore, scope of the present invention is only limited by appended claim and equivalents thereof.
Claims (19)
1. one kind is used for the code signal with identical initial condition and end-state is carried out the method that Turbo decodes, may further comprise the steps: described code signal is carried out the loop iteration computing of Turbo decoding, until satisfy stopping criterion for iteration, with the generating solution coded signal, wherein
In the each time interative computation process of Turbo decoding, carry out forward recursive computing and backward recursive computing from forward direction initial condition tolerance and backward initial condition tolerance respectively, obtain thus forward direction end-state tolerance and backward end-state tolerance,
In the first time of Turbo decoding interative computation, forward direction initial condition tolerance and backward initial condition tolerance are set to predetermined state and measure, and
In the n+1 time interative computation of Turbo decoding, forward direction initial condition tolerance and backward initial condition tolerance are based on that the forward direction end-state that obtains in the n time interative computation is measured and backward end-state is measured and setting, and wherein n is natural number.
2. method according to claim 1, wherein, described forward direction initial condition tolerance comprises probability or the logarithm probability likelihood ratio of each possibility initial condition of described code signal, and described backward initial condition tolerance comprises probability or the logarithm probability likelihood ratio of each possibility end-state of described code signal.
3. method according to claim 2, wherein, forward direction initial condition tolerance and rear being set to initial condition tolerance in the process that predetermined state measures, probability or the logarithm probability likelihood ratio of each possibility initial condition of described code signal are set to predetermined value, and probability or the logarithm probability likelihood ratio of each possibility end-state of described code signal are set to described predetermined value.
4. any one described method in 3 according to claim 1, wherein, the tolerance of the forward direction initial condition in the n+1 time interative computation of Turbo decoding and rear tolerance to initial condition are respectively obtain in the n time interative computation rear to end-state tolerance and forward direction end-state tolerance.
5. any one described method in 3 according to claim 1, wherein, the tolerance of the forward direction initial condition in the n+1 time interative computation of Turbo decoding and rear tolerance to initial condition are respectively that the forward direction end-state that obtains in the n time interative computation is measured and measured to end-state afterwards.
6. any one described method in 3 according to claim 1, wherein, the tolerance of the forward direction initial condition in the n+1 time interative computation of Turbo decoding and rear tolerance to initial condition are by forward direction end-state tolerance and rear the tolerance to end-state that obtains in the n time interative computation is weighted the state measurement that summation obtains.
7. any one described method in 3 according to claim 1, wherein, the tolerance of the forward direction initial condition in the n+1 time interative computation of Turbo decoding and rear to initial condition tolerance be by the forward direction end-state that obtains in the n time interative computation is measured and rear measure to be weighted to end-state multiply each other and product carried out the state measurement that normalization obtains.
8. any one described method in 3 according to claim 1, wherein, described code signal is duobinary system circular recursion system convolutional coded signal.
9. method according to claim 4, wherein, described code signal is duobinary system circular recursion system convolutional coded signal.
10. method according to claim 5, wherein, described code signal is duobinary system circular recursion system convolutional coded signal.
11. method according to claim 6, wherein, described code signal is duobinary system circular recursion system convolutional coded signal.
12. method according to claim 7, wherein, described code signal is duobinary system circular recursion system convolutional coded signal.
13. Turbo decoder that is used for the code signal with identical initial condition and end-state is carried out the Turbo decoding, comprise: at least one decoder module, be used at least one component code of described code signal is carried out the loop iteration computing of Turbo decoding, until satisfy stopping criterion for iteration, with the generating solution coded signal, wherein in the each time interative computation process of Turbo decoding, carry out forward recursive computing and backward recursive computing from forward direction initial condition tolerance and the backward initial condition tolerance of described at least one component code respectively, obtain thus forward direction end-state tolerance and the backward end-state tolerance of described at least one component code, wherein, described Turbo decoder further comprises:
At least one forward-backward algorithm initial condition setting device for forward direction initial condition tolerance and the backward initial condition tolerance of each time at least one component code described in the interative computation that is arranged on the Turbo decoding, and provides it to described at least one decoder module,
Wherein, in the first time of Turbo decoding interative computation, forward direction initial condition tolerance and the backward initial condition tolerance of described at least one component code are set to predetermined state tolerance, and in the n+1 time interative computation of Turbo decoding, forward direction end-state that the forward direction initial condition of described at least one component code tolerance and backward initial condition tolerance are based on described at least one component code that obtains in the n time interative computation is measured and backward end-state measures to arrange, and wherein n is natural number.
14. Turbo decoder according to claim 13, wherein, described forward direction initial condition tolerance comprises probability or the logarithm probability likelihood ratio of each possibility initial condition of described code signal, and described backward initial condition tolerance comprises probability or the logarithm probability likelihood ratio of each possibility end-state of described code signal.
15. Turbo decoder according to claim 14, wherein, in the first time of Turbo decoding interative computation, probability or the logarithm probability likelihood ratio of each possibility initial condition of the described code signal of described at least one forward-backward algorithm initial condition setting device are set to equal predetermined value, and probability or the logarithm probability likelihood ratio of each possibility end-state of described code signal are set to equal described predetermined value.
16. any one described Turbo decoder in 15 according to claim 13, wherein, in the n+1 time interative computation of Turbo decoding, the rear of described at least one component code that described at least one forward-backward algorithm initial condition setting device will obtain in the n time interative computation is set to respectively the forward direction initial condition tolerance of described at least one component code and measures to initial condition afterwards to end-state tolerance and forward direction end-state tolerance, and provides it to described at least one decoder module.
17. any one described Turbo decoder in 15 according to claim 13, wherein, in the n+1 time interative computation of Turbo decoding, the forward direction end-state of described at least one component code that described at least one forward-backward algorithm initial condition setting device will obtain in the n time interative computation tolerance and be set to respectively the forward direction initial condition tolerance of described at least one component code and measure to initial condition afterwards to end-state tolerance afterwards, and provide it to described at least one decoder module.
18. any one described Turbo decoder in 15 according to claim 13, wherein, in the n+1 time interative computation of Turbo decoding, described at least one forward-backward algorithm initial condition setting device is by to the forward direction end-state tolerance of described at least one component code of obtaining in the n time interative computation with being weighted state measurement that summation obtains to end-state tolerance and being set to the forward direction initial condition tolerance of described at least one component code and measuring to initial condition afterwards afterwards, and provides it to described at least one decoder module.
19. any one described Turbo decoder in 15 according to claim 13, wherein, in the n+1 time interative computation of Turbo decoding, described forward-backward algorithm initial condition setting device by to the forward direction end-state tolerance of described at least one component code of in the n time interative computation, obtaining and rear be weighted to multiply each other and product is carried out state measurement that normalization obtains to end-state tolerance be set to the forward direction initial condition tolerance of described at least one component code and measure to initial condition afterwards, and provide it to described at least one decoder module.
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| CN112202456B (en) * | 2020-10-24 | 2022-04-29 | 青岛鼎信通讯股份有限公司 | Turbo decoding method for broadband power line carrier communication |
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| CN1374758A (en) * | 2002-01-30 | 2002-10-16 | 信息产业部电信传输研究所 | Method of preventing state variable overflow in turbo code decoder |
| US20060010362A1 (en) * | 2004-07-09 | 2006-01-12 | Samsung Electronics Co., Ltd. | Method of finding a last state in tail-biting for turbo encoder and apparatus using the same |
| CN1725647A (en) * | 2004-07-21 | 2006-01-25 | 富士通株式会社 | Communicator and wireless communication system |
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| US20060010362A1 (en) * | 2004-07-09 | 2006-01-12 | Samsung Electronics Co., Ltd. | Method of finding a last state in tail-biting for turbo encoder and apparatus using the same |
| CN1725647A (en) * | 2004-07-21 | 2006-01-25 | 富士通株式会社 | Communicator and wireless communication system |
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