CN101119129A - Associated demodulation decoding device for wireless sensing network - Google Patents
Associated demodulation decoding device for wireless sensing network Download PDFInfo
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- CN101119129A CN101119129A CNA2007100706113A CN200710070611A CN101119129A CN 101119129 A CN101119129 A CN 101119129A CN A2007100706113 A CNA2007100706113 A CN A2007100706113A CN 200710070611 A CN200710070611 A CN 200710070611A CN 101119129 A CN101119129 A CN 101119129A
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Abstract
The invention discloses a combined demodulation decode device, comprising at least a demodulator, a surviving route searcher, a state transferring register array and a survive route searcher; wherein the demodulator is used for processing a base band signal which is demodulated first by a RF receive chain circuit, and then a signal I route sign and a Q signal I route sign are demodulated; the surviving route searcher processes the demodulated signs, compares the distance between the possible route and the signs and a shortest route is left as a survive route; the state transferring register array is used for memorizing the transferring state of the store route; and the survive route searcher backdates the survive route and then sends out the sequence. Compared with the traditional device, the invention eliminates the judgment of a demodulating part, thus avoiding the loss of the information and simplifying a demodulating process and decoding process.
Description
Technical field
The present invention relates to a kind of high speed image transmission system that is applicable to building dense city, relate in particular to wherein separate the mediation code translator.
Background technology
In wireless communication system, because the uncertainty of wireless channel simultaneously in order to increase the coverage of wireless network, needs to add channel encoding/decoding apparatus usually outside modulation.The existing mediation code translator structure of separating is seen Fig. 1, it all needs a matched filter to carry out correlation demodulation for I and the Q road that quadrature demodulation goes out, in the end also need to select corresponding decision method according to selected modulation system, the output of judgement also needs through a parallel serial conversion, and the data flow that converts serial to is sent into the decoder of back level.Wherein, described matched filter then is the frequency pilot sign by the front, estimates channel response, utilizes then that the channel estimate is corresponding to carry out matched filtering to the data symbol that receives, to eliminate the influence of channel to the data symbol; Described decision device is according to the modulation system that is adopted, and selects corresponding decision method.For QPSK, then directly with the output of matched filter result as judgement; For 16QAM, multiple mode is then arranged, be used with the decoding of level afterwards, what performance was best is the mode of full soft-decision output, its judgement mode can be represented by the formula:
b
1＝-4r
x+|r
x-2|+|r
x+2|
b
2＝-4+2|r
x|
b
3＝-4r
y+|r
y-2|+|r
y+2|
b
4＝-4+2|r
y|
Described viterbi decoder then is the structure according to the encoder for convolution codes of selecting for use, distance metric value between sequence that calculating rules out and all possible sequence, therefrom select a distance metric value minimum again, promptly the most similar to receiving sequence sequence is as the output of decoding.Wherein, described path distance metric can decompose on each branch road, for one of them branch road (d
I, 0, d
I, 1) the calculating formula of distance metric value be:
E(k，i)＝(b
l-d
i，0)
2+(b
l+1-d
i，l)
2＝b
l 2+b
l+1 2+d
i，0 2+d
i，1 2-2b
ld
i，0-2b
l+1d
i，1
Wherein, b
l 2+ b
L+1 2Be the public keys in all paths, therefore can save; In addition, because d
I, 0And d
I, 1Value be ± 1, d
I, 0 2+ d
I, 1 2Value constant be 2, also identical for all paths, therefore also can save.(k can abbreviation be ± 2 (b i) to E like this
l± b
L+1), two ± choose by d
I, 0, d
I, 1Positive and negative decision.
By top calculating formula as can be seen, the distance metric value is calculated is the distance of some points on the symbol that demodulates and the planisphere, the result who rules out is interim result wherein, still will form a symbol to several symbols that rule out in decoder, carry out the distance metric value and calculate.Because judgement the time inevitably can cause the loss of information, between distance metric value that calculates according to court verdict and the original metric error is arranged like this, this can cause the decline of systematic function.In addition, also caused increasing the weight of of system complexity repeatedly in the processing.
Summary of the invention
The object of the present invention is to provide a kind of joint demodulation code translator that is applied to separate in the wireless communication system mediation decoding joint operation.
The present invention will solve is existingly to separate separating of being in harmonious proportion that code translator exists and be in harmonious proportion the decoded operation complexity, separates the timing judgement and easily causes information loss, causes separating the problem of decoding performance difference of being in harmonious proportion.
To achieve the above object, the present invention comprises that at least demodulator, survivor path searcher, state transitions register array, survivor path recall device; Demodulator is used for the baseband signal that radio frequency reception link demodulates is handled, and demodulates signal I, Q two-way symbol; The survivor path searcher is handled the symbol that demodulates, the distance between it and all possible path relatively, and keep a path that distance is the shortest as survivor path; The state transitions register array is used for the store path transfering state; Survivor path is recalled device survivor path is recalled, and declares the transmission sequence.
The present invention does not distinguish the processing of separating mediation decoding, promptly remove the decision process of carrying out in the demodulator, and in decoder, directly calculate Euclidean distance between the point on demodulation result and the planisphere as the metric in path, and from all possible paths, seek out a path the most close, can avoid like this separating the information loss that timing causes, also simplify the processing of understanding mediation decoding simultaneously.
Description of drawings
Fig. 1 is the modular structure figure of existing joint demodulation code translator.
Fig. 2 is a structured flowchart of the present invention.
Fig. 3 is a survivor path searcher structure chart.
Fig. 4 is the acs unit cut-away view.
Fig. 5 is a state transitions register array work schematic diagram.
Embodiment
The invention will be further described below in conjunction with drawings and Examples.
As Fig. 2, Fig. 3 and shown in Figure 4, the present invention comprises that at least demodulator, survivor path searcher, state transitions register array, survivor path recall device.The survivor path searcher is made up of two groups of path metric value registers group and acs unit.Two groups of path metric value registers group are path metric value registers group 1, path metric value registers group 2.
Described demodulator with equilibrium after and the I of line output, the data of Q two-way, convert to I road symbol preceding, Q road symbol after serial data stream output, send into follow-up processing module as the demodulation result of data and handle.In the survivor path searcher, path metric value registers group 1 is used to store each state point at sometime path metric value, and path metric value registers group 2 is used to be stored in the new path metric value that the path metric value that carries out once each branch road on the basis of path metric value registers group 1 calculates and adds up and obtain after relatively selecting.
The length of path metric value registers group 1 or path metric value registers group 2 is by the decision of the constraint length of selected convolution coder, and the present invention is that 7 convolution coder is the example explanation with constraint length.For constraint length is 7 convolution coder, and the length of path metric value registers group 1 or path metric value registers group 2 is 64.The figure place of register is by the I of demodulator output, the figure place of Q data symbol and the length decision in path in path metric value registers group 1 or the path metric value registers group 2.In decoder of the present invention, the compute depth in path is 40, and the figure place of I, Q data symbol is 8, and the figure place of each register needs 16 like this.
Acs unit shifts and is treated to a basic processing unit with the path of two states, the soft-decision data that its receiving demodulation device is sent into, metric based on storage in the path metric value registers group 1, calculating demodulates the distance between data and two the possible paths, and selects the less path of metric as keeping branch road.For the length of registers group is 64 decoder, needs 32 acs units to handle.Each acs unit structure is identical, includes 4 path distance calculators, 4 path metric value accumulators, two path metric values relatively selector and and path selector.4 path distance calculators are respectively path distance calculator i0, path distance calculator j0, path distance calculator i1 and path distance calculator j1.4 path metric value accumulators are respectively path metric value accumulator i0, path metric value accumulator i1, path metric value accumulator j0 and path metric value accumulator j1, and two path metric value comparison selectors are respectively path metric value, and relatively selector k, path metric value compare selector 1.The path distance calculator is mapped to certain constellation point with the correspondence code radical of current branch road according to selected modulation system, and obtains the output symbol calculating Euclidean distance between the two of current demodulator; The metric of the corresponding state of storage carries out addition in Euclidean distance that the path metric value accumulator calculates the path distance calculator and the path metric value registers group 1, obtains the new metric of this branch road; Path metric value comparison selector compares the new metric in path that two associated path metric value accumulator computes go out, and select the less path of path metric value as surviving path, export the metric of the less road warp of this metric, deposit path metric value registers group 2 in, provide a surviving path index signal simultaneously, point out to have selected any paths as surviving path; Path selector is used to select the less path of metric as survivor path.Described state transitions register array is that each node that branch road is shifted in the path is provided with a register, and the path metric value that is used to note this node correspondence is the reservation branch road indication information of selector output relatively; Described survivor path recall in device and the common viterbi decoder to recall device identical, from all surviving paths, select the path of a paths metric minimum as survivor path, and recall, rule out each code word of this path correspondence, calculate Euclidean distance between the two.
Concrete demodulation coding process of the present invention is: in the survivor path searcher, the output of demodulator is admitted in each acs unit.Described path distance calculator i0 obtains the demodulation result d (k) of input and (k, i0) (k i0) calculates Dui Ying constellation point p, obtains their Euclidean distance with the pairing code word c of a last branch road of state i
E(k，i0)＝(d(k)-p(k，i0))
2＝d(k)
2-2d(k)p(k，i0)+p(k，i0)
2
Two square operations and a multiplication operations and two add operations are mutually arranged in the superincumbent distance calculation formula.Wherein the quadratic term of d (k) is the public keys in all paths, therefore can save in the calculating of path metric value.P (k, i0) be certain some projection on x axle or y axle on the planisphere, its value is artificial the setting when modulation, so convenience in order to calculate, we are with the value Q (8 of each point on the planisphere, 3) form is represented, multiplying each other in the distance calculation formula can be resolved into twice displacement and added last addition like this, thereby avoided multiplying; Simultaneously, for last p on distance calculation formula the right (k, i0) square have only two kinds of possible values, therefore can calculate in advance, be stored in two registers, (k, value i0) directly uses the value substitution formula in the corresponding registers to calculate according to p again.Through above-mentioned simplification, the once calculating of top distance calculation formula only needs twice addition and 3 displacements to realize.Described path distance calculator i0 and path distance calculator i1 calculate respectively on state i, encoder input 0 and the result who obtained in 1 o'clock and the distance metric value of current demand signal sequence; Described path distance calculator j0 and path distance calculator j1 calculate respectively on state j, encoder input 0 and the result who obtained in 1 o'clock and the distance metric value of current demand signal sequence.
Described path metric value accumulator i0 links to each other with path distance calculator i0, he reads the path metric value of the i that gets the hang of that stores in the Sati register, and the result of calculation of path distance calculator i0 is added on this metric, thereby calculate the path total metric of input 0 on the basis of state i.Accordingly, described path metric value accumulator i1 and path metric value accumulator j0, the path of input 0 on the basis of the path of input 1 and state j on the path metric value accumulator j1 difference computing mode i basis, the total metric in the path of input 1 on the basis of state j.
Described path metric value relatively selector k links to each other with path metric value accumulator i0, path metric value accumulator j0, the size of the path metric value that two accumulator of comparison are calculated, select the less path of metric as surviving path, and this metric write the satm register, export a reservation branch road index signal simultaneously, to indicate two paths that link to each other with state m, which path is a surviving path, when surviving path is when state i comes, this index signal is 0, when surviving path is when state j comes, this index signal is 1.Same, described path metric value is selector 1 and path metric value accumulator i1 relatively, and path metric value accumulator j1 links to each other, and selects a surviving path for state 1, writes among the satn, and exports a reservation branch road index signal.
Described state transitions register array is used to write down each state, the state transitions relation on each node in path.It calculates with path metric value and links to each other with the comparison selector that adds up, path metric value is calculated and the comparison selector that adds up in the reservation branch road index signal of path metric value comparison selector write in the register of correspondence in the register array.With constraint length is that 7 convolution code is an example, has 64 states, and path is 40, and the bit wide of register only needs 1, and the register space that needs of this array is 40*64bit like this.
Described survivor path is recalled the metric registers group of device inquiry end-state, the metric of each register in the comparand register group, find out the state of metric metric minimum, the reservation branch road index signal of mark in the register of the inquiry corresponding state from the state transitions register array again, judge the state of a node on the path that enters this state thus, reciprocal thus, go ahead from the terminal point in path and to review, finally solve the most close coded sequence of this sequence, realize decoding judgement restituted signal.
In sum, joint demodulation code translator of the present invention, simplified the work of demodulator, in demodulator, removed judging module, and improved path distance calculator in the survivor path searcher, and avoided the information dropout that in the demodulation judging process, causes, make the sequence of decoding judgement output with to receive information sequence the most approaching, simultaneously on the complexity of handling, the present invention is close with traditional demodulator decorder processing complexity.
Claims (5)
1. joint demodulation code translator that is applied to wireless sense network is characterized in that this device comprises that at least demodulator, survivor path searcher, state transitions register array, survivor path recall device; Demodulator is used for the baseband signal that radio frequency reception link demodulates is handled, and demodulates signal I, Q two-way symbol; The survivor path searcher is handled the symbol that demodulates, the distance between it and all possible path relatively, and keep a path that distance is the shortest as survivor path; The state transitions register array is used for the store path transfering state; Survivor path is recalled device survivor path is recalled, and declares the transmission sequence.
2. a kind of joint demodulation code translator that is applied to wireless sense network as claimed in claim 1 is characterized in that described survivor path searcher comprises path metric value registers group and the acs unit that links to each other with the path metric value registers group.
3. a kind of joint demodulation code translator that is applied to wireless sense network as claimed in claim 2 is characterized in that described acs unit comprises path distance calculator, path metric accumulator, path relatively selector and path selector; The path distance calculator is used to calculate the current Euclidean distance between symbol and the particular constellation point that demodulates; The path metric accumulator is used to calculate the entire path metric; Path relatively selector is used for two path metric values that point to same state of comparison, and selects the less path of a paths metric as surviving path; Path selector is used to select the less path of metric as survivor path.
4. a kind of joint demodulation code translator that is applied to wireless sense network as claimed in claim 3 is characterized in that the directly I to demodulating of described path distance calculator, and a plurality of information bits that comprise in the Q two-way symbol are made the as a whole distance calculation of carrying out.
5. a kind of joint demodulation code translator that is applied to wireless sense network as claimed in claim 1, it is characterized in that described demodulator only carries out the demodulation to data, saved the function that data are adjudicated, done a plurality of information bits that comprise in I, the Q two-way symbol as a whole.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101350634B (en) * | 2008-03-05 | 2012-08-15 | 中国科学院嘉兴无线传感网工程中心 | Method for modulating short-wave communication frequency-sweeping head of wireless sensing network |
| CN103346860A (en) * | 2013-06-21 | 2013-10-09 | 安徽华东光电技术研究所 | Decoding unit of wireless transmission system and decoding method thereof |
| CN104468043A (en) * | 2014-12-04 | 2015-03-25 | 福建京奥通信技术有限公司 | Quick pbch convolutional code decoding device and method applied to lte |
-
2007
- 2007-08-30 CN CNA2007100706113A patent/CN101119129A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101350634B (en) * | 2008-03-05 | 2012-08-15 | 中国科学院嘉兴无线传感网工程中心 | Method for modulating short-wave communication frequency-sweeping head of wireless sensing network |
| CN103346860A (en) * | 2013-06-21 | 2013-10-09 | 安徽华东光电技术研究所 | Decoding unit of wireless transmission system and decoding method thereof |
| CN103346860B (en) * | 2013-06-21 | 2016-04-27 | 安徽华东光电技术研究所 | A kind of decoding unit of wireless transmitting system and interpretation method thereof |
| CN104468043A (en) * | 2014-12-04 | 2015-03-25 | 福建京奥通信技术有限公司 | Quick pbch convolutional code decoding device and method applied to lte |
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Owner name: CAS JIAXING WIRELESS SENSOR NETWORK ENGINEERING CE Free format text: FORMER OWNER: CAS JIAXING CENTER MICROSYSTEMS INTITUTE BRANCH CENTER Effective date: 20100129 |
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Effective date of registration: 20100129 Address after: 2, building 1, No. 778 Asia Pacific Road, Nanhu District, Zhejiang, Jiaxing Province, China: 314000 Applicant after: Jiaxing Wireless Sensor Network Engineering Center, Chinese Academy of Sciences Address before: A, building four, block JRC, Asia Pacific Road, Nanhu District, Zhejiang City, Jiaxing Province, China: 314000 Applicant before: Microsystem Inst. Branch Center, Jiaxing Center, CAS |
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Open date: 20080206 |