CN206585546U - Tail biting folding coding system - Google Patents
Tail biting folding coding system Download PDFInfo
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- CN206585546U CN206585546U CN201621322677.8U CN201621322677U CN206585546U CN 206585546 U CN206585546 U CN 206585546U CN 201621322677 U CN201621322677 U CN 201621322677U CN 206585546 U CN206585546 U CN 206585546U
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Abstract
The utility model discloses a kind of tail biting folding coding system, including coder module and decoder module, the coder module receives data frame from data receiver module, data frame after encoded is transmitted to data logger module after being decoded by the decoder module, decoder module includes survivor memory unit, branch metric unit, comparing unit, controller unit, positive sequence decoding unit and backward decoding unit, the positive sequence decoding unit is connected by survivor memory unit with branch metric unit, branch metric unit is connected by comparing unit with the controller unit, the controller unit decodes delivery outlet with positive sequence respectively and the backward decoding unit is connected, the backward decoding unit is connected with backward decoding delivery outlet, the branch metric unit is used to find out the branched measurement value that optimal path is produced during positive sequence decoding unit is decoded.The utility model can reduce the bit error rate of data frame, improve systematic function, the stability of strengthening system.
Description
Technical field：
The utility model is related to a kind of decoding system, more particularly to a kind of tail biting folding coding system.
Background technology：
TD-LTE is the once leap of mobile communication standard technically, plays and holds in the development of GSM
The original state and done state of encoder are to determine before effect under opening, traditional convolutional encoding, tail biting convolutional encoding
That original state and done state are also all to determine and being information to be sent last six, this is also just determined before decoding
Do not know original state, it is stateful to attempt institute during decoding, then determines which path used finally according to metric, therefore can
To find out that tail biting folding coding is more much higher than traditional folding coding algorithm complex, and decoding difficulties increased.
Learnt according to literature search, the prior art of tail biting folding coding algorithm has：（1）Li little Wen, Luo Youbao exist《One
Plant the Viterbi decoding algorithms applied to LTE systems》（Referring to《Telecommunication science》7th phase in 2010）Proposed in one text
Improved circulation viterbi decoding algorithms, it is this to make use of a kind of thought that K+m algorithms are provided, i.e., only in the end weight of code block
During multiple sub-fraction, the first and last state of true form block may be identical, especially signal to noise ratio it is big in the case of, if now returned
Path first and last state of tracing back is identical, then it is correct to decode output, if backtracking path first and last state is differed, before path
The error rate of Lc state is maximum, it is therefore necessary to taken corrective action on the basis of K+m algorithms, finally will be wrong in path
State is replaced by mistake, it is ensured that the first and last state in path is identical, so as to improve the correctness of decoding；（2）Wang Jun exists《Tail biting is rolled up
The interpretation method and device of product code》（Referring to CN101969308 B）Proposed in one text from the cumulative metric of sequence to be decoded most
It is worth corresponding state point greatly to start to do traceback decoding, obtains the first decoding result, and judge the original state of the first decoding result
It is whether identical with end-state；If it is not the same, then since first decoding result in original state point traceback decoding, obtain
Second decoding result, and amount of bits inconsistent in the first decoding result and the second decoding result is compared with predetermined threshold
Compared with；According to comparative result output decoding result；（3）Wei Jing it is prosperous《The interpretation method and device of tail-biting convolutional code》（Referring to
CN101369817 B）The obtained sequence that repeatedly joined end to end afterwards to same transmission block is proposed in one text and carries out Wei Te
Than decoding, after the transmission block decoding of each in the sequence terminates, the maximum path obtained according to the decoding judges whether full
Sufficient output condition；When judgement meets output condition, using the maximum path as backtracking path, the decoding number of the sequence is exported
According to.
In LTE system, sub-block interleaving process is carried out before channel decoding, sub-block intertexture purpose is to be transmitted across information
Burst error discretization in journey, although can make burst error discretization by sub-block interleaving process, but still suffer from and entirely treat
Decoding information block error code skewness, i.e., the bit error rate skewness of half part before and after information sequence, and because can only be in the past
Decode successively backward, so the problems such as bit error rate is high can be caused.
Utility model content：
Technical problem to be solved in the utility model is：The deficiencies in the prior art are overcome effectively to be carried there is provided one kind
High decoding performance, reduces the tail biting folding coding system of the bit error rate.
The utility model is for the technical solution adopted for solving the technical problem：
A kind of tail biting folding coding system, including coder module and decoder module, the coder module is from data
Receiver module receive data frame, it is encoded after data frame by the decoder module decode after be transmitted to data logger
Module, the decoder module includes survivor memory unit, branch metric unit, comparing unit, controller unit, positive sequence
Decoding unit and backward decoding unit, the positive sequence decoding unit pass through the survivor memory unit and the branch metric
Unit is connected, and the branch metric unit is connected by comparing unit with the controller unit, the controller unit difference
Delivery outlet is decoded with positive sequence and the backward decoding unit is connected, and the backward decoding unit is connected with backward decoding delivery outlet.
The survivor memory unit is used to choose optimal decoding path, and the branch metric unit is used to find out just
The branched measurement value that optimal path is produced during the decoding of sequence decoding unit.
The comparing unit compares two branched measurement values of optimal path generation, the controller unit using comparator
The comparative result control selections positive sequence produced according to comparing unit decodes delivery outlet or selects backward to translate by backward decoding unit
Code delivery outlet.
The decoder module decodes delivery outlet by the positive sequence or the backward decodes delivery outlet by the number after decoding
The data logger module is transferred to according to frame, the positive sequence that the positive sequence decoding unit is used for data frame is decoded, and the backward is translated
The backward that code unit is used for data frame is decoded, and positive sequence decoding is that the data to decode frame that will be received is arranged in order, and backward is translated
Code is that the data to decode frame that will be received is arranged in reverse order.
The decoder module uses Viterbi decoders, and the coder module is using the FPGA's of Xilinx companies
Convolution coder.
Folding coding comprises the following steps in tail biting folding coding system：
（1）Receive data frame and carry out positive sequence decoding simultaneously；
（2）Draw metric：The process decoded according to positive sequence, find out the corresponding metric state_pm of optimal path (q,
K/2) and metric state_pm (q, K), wherein metric state_pm (q, k) be 1 to k all path metric value add up it
With；
（3）Judge and export decoding result：If 2 times of metric state_pm (q, K/2) are more than metric state_pm
(q, K), then decoded using positive sequence, and positive sequence decoding is used as decoding result from positive sequence decoding delivery outlet output；If metric state_
2 times of pm (q, K/2) be not more than metric state_pm (q, K), then using backward decode, backward decoding as decoding result from
Backward decoding delivery outlet output.
In step（3）In backward decoding be that the data to decode frame that will be received is arranged in reverse order, then decode again；It is inverse
Sequence decoding detailed process is as follows：
A. the data of a data frame have been received first, whole data frame tandem has been overturned, i.e. (i)=d (K+1-i),
I=1,2 ... ..., K；
B. decoding the 1st is started according to maximum likelihood algorithm, it is assumed that end state is q, travels through 64 kinds of states, passes through state
Q releases 1bit information, i.e., primary to send K of data frame.
C. according to the 1bit information that draws, extrapolate second state, i.e., it is primary to send K-1 of data frame, according to this
The method of sample is decoded successively, and until the K+Ld moment, wherein Ld represents tail biting convolutional encoding dicision depth.
D. optimal path state_sequence (q, K+Ld) is selected according to metric state_pm (q, K+Ld), if this
When the moment state of t=K moment and t=0 as then decoding output, otherwise, then carry out step d and continue to decode, decode until t=(K+
Lc+Ld) mod K moment, wherein Lc is correction depth.
E. optimal branched measurement value state_pm (q, K+Lc+Ld) is found out from t=(K+Lc+Ld) mod K moment, is opened
Begin to recall from the moment of t=(K+Lc+Ld) mod K to t=0, the corresponding status switch of this paths be state_sequence (q,
K+Lc+Ld), 1 to K+Lc value is translated, by the 1st, 2 ..., Lc value K+1, K+2 ..., K+Lc value are replaced, and are then exported
The preceding K value replaced, that is, the final output result decoded.
F. it is the above-mentioned information first and last translated is out of position, complete backward decoding.
Positive beneficial effect of the present utility model is：
If the 1st, in the utility model 2 times of metric state_pm (q, K/2) be more than state_pm (q, K), then finally translate
Code result is decoded using positive sequence, because now positive sequence decoding is better than backward performance；Otherwise backward decoding is carried out, because now exporting
Backward decoding is better than using positive sequence performance as decoding result, this by the way of positive sequence decoding and backward decoding are combined,
The bit error rate of block of information can be effectively reduced, decoding efficiency is improved.
2nd, the utility model can improve the performance of whole system, the stability of strengthening system, in addition the inventive method energy
Next generation mobile communication field is enough efficiently applied to, is that next-generation mobile communications are done according to LTE and LTE-A consensus standard
Technological reserve, with good practicality and economy.
Brief description of the drawings：
Fig. 1 is the structure connection signal block diagram of the utility model tail biting folding coding system；
Fig. 2 is decoder module inner structure connection signal block diagram in Fig. 1；
Fig. 3 is to decode schematic flow sheet in the utility model tail biting folding coding system decoder.
Embodiment：
The utility model is further explained and explanation with specific embodiment below in conjunction with the accompanying drawings：
Referring to Fig. 1, Fig. 2 and Fig. 3：In figure, 1- data receiver modules, 2- coder modules, 3- decoder modules, 4- numbers
According to follower module, 3-1- positive sequence decoding units, 3-2- survivor memory units, 3-3- branch metric units, 3-4- compares
Unit, 3-5- controller units, 3-6- positive sequences decoding delivery outlet, 3-7- backward decoding units, 3-8- backwards decoding delivery outlet.
Embodiment：A kind of tail biting folding coding system, including coder module 2 and decoder module 3, coder module 2
From data receiver module 1 receive data frame, be encoded after data frame decoded by decoder module 3 after to be transmitted to data defeated
Go out device module 4, decoder module 3 includes survivor memory unit 3-2, branch metric unit 3-3, comparing unit 3-4, control
Device unit 3-5, positive sequence decoding unit 3-1 and backward decoding unit 3-7, positive sequence decoding unit 3-1 store single by survivor path
First 3-2 is connected with branch metric unit 3-3, and branch metric unit 3-3 is connected by comparing unit 3-4 with controller unit 3-5,
Controller unit 3-5 respectively with positive sequence decoding delivery outlet 3-6 and backward decoding unit 3-7 be connected, backward decoding unit 3-7 with it is inverse
Sequence decodes delivery outlet 3-8 connections.
Survivor memory unit 3-2 is used to choose optimal decoding path, and branch metric unit 3-3 is used to find out positive sequence
The branched measurement value that optimal path is produced during decoding unit 3-1 decodings.
Comparing unit 3-4 compares two branched measurement values of optimal path generation, controller unit 3-5 roots using comparator
According to the comparing unit 3-4 comparative result control selections positive sequence decoding delivery outlet 3-6 produced or by backward decoding unit 3-7 selections
Backward decoding delivery outlet 3-8.
Decoder module 3 decodes delivery outlet 3-6 by positive sequence or backward decodes delivery outlet 3-8 and passes the data frame after decoding
Data logger module 4 is defeated by, the positive sequence that positive sequence decoding unit 3-1 is used for data frame is decoded, and backward decoding unit 3-7 is used to count
Decoded according to the backward of frame, positive sequence decoding is that the data to decode frame that will be received is arranged in order, backward decoding is to receive
Data to decode frame be arranged in reverse order.
Decoder module 3 uses Viterbi decoders, and coder module 2 is compiled using the FPGA of Xilinx companies convolution
Code device.
Folding coding comprises the following steps in tail biting folding coding system：
（1）Receive data frame and carry out positive sequence decoding simultaneously；
（2）Draw metric：The process decoded according to positive sequence, find out the corresponding metric state_pm of optimal path (q,
K/2) and metric state_pm (q, K), wherein metric state_pm (q, k) be 1 to k all path metric value add up it
With；
（3）Judge and export decoding result：If 2 times of metric state_pm (q, K/2) are more than metric state_pm
(q, K), then decoded using positive sequence, and positive sequence decoding is used as decoding result from positive sequence decoding delivery outlet 3-6 outputs；If metric
2 times of state_pm (q, K/2) are not more than metric state_pm (q, K), then are decoded using backward, and backward decoding is used as decoding
As a result from backward decoding delivery outlet 3-8 outputs.
In step（3）In backward decoding be that the data to decode frame that will be received is arranged in reverse order, then decode again；It is inverse
Sequence decoding detailed process is as follows：
A. the data of a data frame have been received first, whole data frame tandem has been overturned, i.e. (i)=d (K+1-i),
I=1,2 ... ..., K；
B. decoding the 1st is started according to maximum likelihood algorithm, it is assumed that end state is q, travels through 64 kinds of states, passes through state
Q releases 1bit information, i.e., primary to send K of data frame.
C. according to the 1bit information that draws, extrapolate second state, i.e., it is primary to send K-1 of data frame, according to this
The method of sample is decoded successively, and until the K+Ld moment, wherein Ld represents tail biting convolutional encoding dicision depth.
D. optimal path state_sequence (q, K+Ld) is selected according to metric state_pm (q, K+Ld), if this
When the moment state of t=K moment and t=0 as then decoding output, otherwise, then carry out step d and continue to decode, decode until t=(K+
Lc+Ld) mod K moment, wherein Lc is correction depth.
E. optimal branched measurement value state_pm (q, K+Lc+Ld) is found out from t=(K+Lc+Ld) mod K moment, is opened
Begin to recall from the moment of t=(K+Lc+Ld) mod K to t=0, the corresponding status switch of this paths be state_sequence (q,
K+Lc+Ld), 1 to K+Lc value is translated, by the 1st, 2 ..., Lc value K+1, K+2 ..., K+Lc value are replaced, and are then exported
The preceding K value replaced, that is, the final output result decoded.
F. it is the above-mentioned information first and last translated is out of position, complete backward decoding.
System reception data enter row decoding when receiving during work, find out the corresponding metric state_pm of optimal path
(q, K/2) and metric state_pm (q, K), if 2 times of metric state_pm (q, K/2) are more than state_pm (q, K),
Then final decoding result is decoded using positive sequence；Otherwise backward decoding is carried out, final decoding result is decoded using backward.
It is described above, only it is preferred embodiments of the present utility model, does not make any formal to the utility model
Limitation, it is every according to technical spirit of the present utility model above example is made it is any it is simple modification, equivalent variations with
Modification, still falls within the protection domain of technical solutions of the utility model.
Claims (4)
1. a kind of tail biting folding coding system, including coder module and decoder module, it is characterized in that：The coder module
From data receiver module receive data frame, it is encoded after data frame by the decoder module decode after be transmitted to data
Follower module, the decoder module includes survivor memory unit, branch metric unit, comparing unit, controller list
Member, positive sequence decoding unit and backward decoding unit, the positive sequence decoding unit by the survivor memory unit with it is described
Branch metric unit is connected, and the branch metric unit is connected by comparing unit with the controller unit, the controller
Unit decodes delivery outlet with positive sequence respectively and the backward decoding unit is connected, and the backward decoding unit is decoded with backward and exported
Mouth connection, the decoder module uses Viterbi decoders, and the coder module uses the FPGA of Xilinx companies volume
Product encoder.
2. tail biting folding coding system according to claim 1, it is characterized in that：The survivor memory unit is used to select
Optimal decoding path is taken, the branch metric unit is used to find out what optimal path during positive sequence decoding unit is decoded was produced
Branched measurement value.
3. tail biting folding coding system according to claim 1, it is characterized in that：The comparing unit is compared using comparator
Two branched measurement values that optimal path is produced, the comparative result control selections that the controller unit is produced according to comparing unit
Positive sequence decodes delivery outlet or selects backward to decode delivery outlet by backward decoding unit.
4. tail biting folding coding system according to claim 1, it is characterized in that：The decoder module passes through the positive sequence
Decode delivery outlet or the backward decoding delivery outlet by the data frame transfer after decoding give the data logger module, it is described just
The positive sequence that sequence decoding unit is used for data frame is decoded, and the backward that the backward decoding unit is used for data frame is decoded, positive sequence decoding
It is that the data to decode frame that will be received is arranged in order, backward decoding is that the data to decode frame that will be received is arranged in reverse order
Row.
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