CN106130656B - Light ofdm signal coded modulation and demodulating system and method based on polarization code - Google Patents
Light ofdm signal coded modulation and demodulating system and method based on polarization code Download PDFInfo
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- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
- H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/25—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM]
- H03M13/251—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM] with block coding
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Abstract
The present invention proposes a kind of light ofdm signal coded modulation based on polarization code and demodulating system and method, the system comprises polarization code coding unit, high-order map unit, subcarrier mapping unit, takes pilot cell, OFDM modulation unit, light emitting and receiving unit, OFDM demodulation unit, subcarrier recovery unit, high-order de-mapping unit, polarization code decoding unit.User information is mapped to corresponding carriers by high order modulation after polarization code encodes, and realizes that frequency-region signal to the conversion of time-domain signal, is then modulated on channel and is transmitted after IFFT.Receiving end carries out FFT to signal, and sub-carrier signal restores, and restores original subscriber's signal after the soft demodulation of high-order and the SC decoding of polarization code, realizes the transmission of whole system.Polarization code and high order modulation and carrier wave mapping are combined by the present invention, can available frequency spectrum resource in flexible Application system, the introducing of high order modulation technique promotes the transmission rate of information, and the introducing of polarization code promotes the reliability that information is transmitted.
Description
Technical field
The invention belongs to technical field of photo communication, and in particular, to be a kind of by polarization code and light OFDM
The modulation-demo-demodulation method and corresponding system that (Orthogonal Frequency Division Multiple) signal combines, are used
Channel coding and high order modulation lifting system performance simultaneously.
Background technique
With the development of internet technology, data traffic constantly increases, and demand of the people to network bandwidth is increasing.One
Aspect causes the limited band resource of script more rare, and message transmission rate is on the other hand enabled to have exceeded prior art institute
The peak transfer rate of support.However traditional channel coding method is used alone or traditional high order modulation side is used alone
Formula can no longer meet the demand of these two aspects.And polarization code a kind of reaches letter by stringent mathematical proof as currently the only
The constructivity encoding scheme of road capacity, possesses lower computation complexity and higher performance.By by polarization code and light
The method that OFDM modulation method combines, can effectively solve limited neatly by modulates information to specific available subcarrier
Band resource problem.Simultaneously by the method for high order modulation, so that reducing signal under the premise of message transmission rate is constant
Detection, signal processing, decoding character rate, reduce the bit error rate of entire transmission process.I.e. in certain signal processing rate
Under, by high order modulation improve data transmission rate, while by and this high performance channel coding of polarization code combination,
Reduce the bit error rate.
By the retrieval to existing literature, the Erdal Arikan from Bilkent University in 2009
Publish thesis " Channel on the 7th phase of volume 55 of IEEE TRANSACTIONS ON INFORMATION THEORY
Polarization:A Method for Constructing Capacity-Achieving Codes for Symmetric
Binary-Input Memoryless Channels ", theory propose the construction and interpretation method of this pattern of polarization code,
But related articles only theoretically propose polarization code, there is no excessive further investigation is done in application field.
It finds by literature search again, comes from South Korea Pohang University of Science and Technology
(POSTECH) Dong-Min Shin et al. was in volume 16 the 6th in IEEE COMMUNICATIONS LETTERS in 2012
Publish thesis " Mapping Selection and Code Construction for 2m-ary Polar-Coded on phase
Modulation (the polarization code mapping selection and code construction of 2 m power are modulated) ".The author proposes a variety of based on polarization
The selection criterion of mapping ruler in the m-pam modulation of code.However entire modulating rule only completes the modulation on single carrier,
Limited frequency spectrum resource can not neatly be used.
Summary of the invention
For the problem that the band resource occurred in available data transmission is limited, message transmission rate is continuously improved, this hair
It is bright to propose a kind of light ofdm signal coded modulation based on polarization code and demodulating system and method, utilize polarization code in a frequency domain
The light OFDM modulation technique that channel coding technology is combined with high order modulation technique, can neatly by modulates information to it is specific can
On carrier wave, limited band resource can be made full use of and improve data under the premise of guaranteeing certain bit error rate
Transmission rate.
To achieve the above object, the invention adopts the following technical scheme:
First purpose according to the present invention, provides a kind of light ofdm signal coded modulation based on polarization code and demodulation is
System, the system comprises:
Polarization code coding unit, needed for being encoded into the user information for needing to transmit by the coding rule of polarization code
The code word of transmission；
High-order map unit carries out high-order mapping for the code word after encoding polarization code, is mapped on planisphere；
Signal after high-order maps is mapped on available subcarrier by subcarrier mapping unit in order；
Pilot cell is taken, takes pilot tone every a certain number of frequency domain ofdm signals according to Block-type pilot structure, is used for the later period
Channel estimation；
OFDM modulation unit carries out IFFT transformation, when the frequency domain ofdm signal that subcarrier mapping unit transmits is converted to
Domain ofdm signal is transmitted, and adds cyclic prefix CP before each time domain OFDM signal；
Light emitting and receiving unit, the time domain OFDM signal for sending OFDM modulation unit are modulated to light carrier,
It transmits in fiber medium, is received in receiving end with photodetector；
OFDM demodulation unit removes the cyclic prefix CP of each time domain OFDM signal, and carries out FFT to the data of removal CP
Operation, operation result are used for later period channel estimation；
Channel estimating unit is connected, for leading to the input terminal of the output end of OFDM demodulation unit, subcarrier recovery unit
The pilot tone X saved in transmitting terminal is crossed, and the frequency domain letter obtained after the taken pilot tone in receiving end is by transmission and respective handling
Number Y calculates frequency transfer function according to formula, is averaged, obtains to each frequency transfer function summation that each pilot tone calculates
As the estimated value of entire channel frequency transition function, the signal of transmitting terminal respective frequencies point is recovered thus according to formula
Value；
Subcarrier recovery unit, the frequency domain ofdm signal for restoring signal estimation unit are anti-by subcarrier maps rule
Push away the signal format after reverting to high-order mapping；
High-order de-mapping unit, for the frequency-region signal after restoring subcarrier by soft de-mapped at posterior probability sequence
Column, convenient for the decoding of subsequent polarization code；
Polarization code decoding unit, the posterior probability sequence for generating high-order de-mapping unit are produced by polarization code decoding
Raw original user's sequence, completes final transmission.
Preferably, the polarization code coding unit selects suitable polarization code coding code length N and code rate R, wherein code
The integral number power that long N is 2, and according to code length N and code rate R selection information channel and fixed bit channel.
Preferably, the high-order map unit maps the binary bit sequence that polarization code coding generates with high-order
Method be mapped to each point on respective constellation figure.
Preferably, the subcarrier mapping unit presses each data point of the frame data after high-order maps
Go on Sequential Mapping to different sub-carrier positions, specific mapping ruler is as follows: the frame data format after high-order mapping is
X1,X2,…XN/m, N is the code length of polarization code, and m is the order of high-order mapping, and available subcarrier is U in an ofdm signalp,
Up+1,…Uq, p is the start sequence number of available subcarrier, q be can subcarrier termination serial number, the sum of available subcarrier is q-p+
1, according to numeric order by X1It is mapped to U1, by X2It is mapped to U2, and so on；If available subcarrier number q-p+1 is less than a frame number
According to data length N/m, then the data of beginning are mapped in order on the available subcarrier of next ofdm signal；If available
Sub-carrier number q-p+1 is greater than the data length N/m of a frame data, then is mapped to the data after the mapping of next frame high-order in order
On remaining subcarrier；It, will be electric by the symmetrical mode of Hermitian conjugate if there is the case where complex data point after modulator approach modulation
Flat to correspond on subcarrier, the subcarrier corresponding position for the frequency range not used is 0.
Preferably, the OFDM modulation unit, including IFFT module and plus cyclic prefix CP module, IFFT module will be sub
The frequency-region signal that carrier wave map unit is sent is transformed to time-domain signal；Add cyclic prefix CP module before each time-domain signal plus follows
Ring prefix CP.
Preferably, the OFDM demodulation unit includes: removal cyclic prefix CP module and FFT module, FFT module by when
Domain ofdm signal reverts to frequency domain ofdm signal；Removal cyclic prefix CP module removes the cyclic prefix of each time domain OFDM signal
CP。
Preferably, the high-order de-mapping unit, according to Bayesian formula, calculate user information be 0 and 1 it is corresponding
Posterior probability sequence, the input as the decoding of rear class polarization code.
Second purpose according to the present invention provides a kind of light ofdm signal coded modulation based on polarization code and demodulation side
Method, comprising:
Polarization code coding step, needed for being encoded into the user information for needing to transmit by the coding rule of polarization code
The code word of transmission；
High-order mapping step carries out high-order mapping for the code word after encoding polarization code, is mapped on planisphere；
Signal after high-order maps is mapped on available subcarrier by subcarrier maps step；
Pilot tone step is taken, takes pilot tone every a certain number of frequency domain ofdm signals according to Block-type pilot structure, is used for the later period
Channel estimation；
OFDM modulation step carries out IFFT transformation, the frequency domain ofdm signal of subcarrier maps step is converted to time domain
Ofdm signal is transmitted, and adds cyclic prefix CP before each time domain OFDM signal；
Light emitting and receiving step, for the time domain OFDM signal of OFDM modulation step to be modulated to light carrier, in light
It transmits in minute matter, is received in receiving end with photodetector；
OFDM demodulation step removes the cyclic prefix CP of each time domain OFDM signal, and carries out FFT to the data of removal CP
Operation, operation result are used for later period channel estimation；
Channel estimation steps, by the pilot tone X saved in transmitting terminal, and the taken pilot tone in receiving end by transmission and
The frequency-region signal Y obtained after respective handling calculates frequency transfer function according to formula, and each summation calculated each pilot tone takes
It is average, the estimated value as entire channel frequency transition function is obtained, recovers the corresponding frequency of transmitting terminal thus according to formula
The signal value of rate point；
Subcarrier recovering step, after the frequency domain ofdm signal for restoring signal estimating step reverts to high-order mapping
Signal format；
Higher-order solutions mapping step, for the frequency-region signal after restoring subcarrier by soft de-mapped at posterior probability sequence
Column, convenient for the decoding of subsequent polarization code；
Polarization code decoding procedure, the posterior probability sequence for generating higher-order solutions mapping step are produced by polarization code decoding
Raw original user's sequence, completes final transmission.
User transmits data in the present invention, is mapped to corresponding carriers by high order modulation appropriate after polarization code encodes,
Realize that frequency-region signal to the conversion of time-domain signal, is then modulated on corresponding channel and is transmitted after IFFT.Receiving end pair
Signal carries out FFT, and sub-carrier signal restores, and restores original subscriber's signal after the soft demodulation of high-order and the SC decoding of polarization code, realizes
The transmission of whole system.
Compared with prior art, the present invention have it is following the utility model has the advantages that
The invention proposes the technologies for combining polarization code with light ofdm signal coded modulation, and it is logical to efficiently solve light
The letter problem that system spectral resources are limited and message transmission rate is not high.Polarization code as it is a kind of can reach Shannon tolerance and
There is the channel coding algorithm of lower encoding and decoding complexity, reduce the bit error rate in message transmitting procedure, improves the reliable of system
Property.The introducing of high-order mapping improves the information content that single symbol carries, and improves the message transmission rate of optical communication system.Light
OFDM is modulated so that whole system has preferable mitigating frequency-selective fading and narrow-band characteristic.Can with flexible choice decay compared with
Small subcarrier carries out data transmission, while signal is concentrated in a narrow band signal, and it is limited effectively to solve frequency spectrum resource
Problem improves the band efficiency of system.
Detailed description of the invention
Upon reading the detailed description of non-limiting embodiments with reference to the following drawings, other feature of the invention,
Objects and advantages will become more apparent upon:
Fig. 1 is the functional block diagram of a preferred embodiment of the invention；
Fig. 2 is the subcarrier maps rule schema of a preferred embodiment of the invention；
Fig. 3 is specific mistake of the preferred embodiment of the invention by the emulation experiment by polarization code applied to light OFDM example
Rate curve.
Specific implementation method
The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field
Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field
For personnel, without departing from the inventive concept of the premise, several changes and improvements can also be made.These belong to the present invention
Protection scope.
As shown in Figure 1, a kind of light ofdm signal coded modulation and demodulating system based on polarization code, which is characterized in that institute
The system of stating includes:
Polarization code coding unit, needed for being encoded into the user information for needing to transmit by the coding rule of polarization code
The code word of transmission；
High-order map unit carries out high-order mapping for the code word after encoding polarization code, is mapped on planisphere；
Signal after high-order maps is mapped on available subcarrier by subcarrier mapping unit in order；
Pilot cell is taken, takes pilot tone every a certain number of frequency domain ofdm signals according to Block-type pilot structure, is used for the later period
Channel estimation；This operation is completed before IFFT；
OFDM modulation unit carries out IFFT transformation, when the frequency domain ofdm signal that subcarrier mapping unit transmits is converted to
Domain ofdm signal is transmitted, and adds cyclic prefix CP before each time domain OFDM signal；
Light emitting and receiving unit, the time domain OFDM signal for sending OFDM modulation unit are modulated to light carrier,
It transmits in fiber medium, is received in receiving end with photodetector；
OFDM demodulation unit removes the cyclic prefix CP of each time domain OFDM signal, and carries out FFT to the data of removal CP
Operation, operation result are used for later period channel estimation；
Channel estimating unit is connected, for leading to the input terminal of the output end of OFDM demodulation unit, subcarrier recovery unit
The pilot tone X saved in transmitting terminal is crossed, and the frequency domain letter obtained after the taken pilot tone in receiving end is by transmission and respective handling
Number Y calculates frequency transfer function according to formula, and each summation calculated each pilot tone is averaged, and is obtained as entire channel
The estimated value of frequency translation probability function recovers the signal value of transmitting terminal respective frequencies point thus according to formula；
Subcarrier recovery unit, the frequency domain ofdm signal for restoring signal estimation unit are anti-by subcarrier maps rule
Push away the signal format after reverting to high-order mapping；
High-order de-mapping unit, for the frequency-region signal after restoring subcarrier by soft de-mapped at posterior probability sequence
Column, convenient for the decoding of subsequent polarization code；
Polarization code decoding unit, the posterior probability sequence for generating high-order de-mapping unit are produced by polarization code decoding
Raw original user's sequence, completes final transmission.
The polarization code coding unit encodes two by generation user data and polarization code and forms.
The light emitting and receiving unit are by sending preceding modulation, fibre channel transmission, photodetector reception three parts group
At.
In Fig. 1, channel estimation is connected with the input terminal of the output end of OFDM demodulation unit, subcarrier recovery unit, utilizes
Pilot tone acquired by early period carries out channel estimation operation.
In one embodiment, the polarization code coding unit selects suitable polarization code coding code length N and code rate R, and
According to code length N and code rate R selection information channel and fixed bit channel, the integral number power that wherein code length N is 2, such as 512,
1024,2048 etc.；The method of selection channel can be Pasteur's parametric method, Gaussian approximation or degree distribution.
In one embodiment, the high-order map unit, the binary bit sequence that polarization code coding is generated are high
Rank mapping method be mapped on each point of respective constellation figure, wherein the high-order mapping method selected can be QPSK, 4PAM,
The methods of 4QAM, 16QAM, 64QAM etc..
In one embodiment, the subcarrier mapping unit, by each number of a symbol after high order modulation
Strong point is mapped to different sub-carrier positions up in order, if occurring the case where complex data point (ratio after modulator approach modulation
Such as the modulator approach of 16QAM etc), level is corresponded on subcarrier by Hermitian conjugate symmetrical mode, is not used
The subcarrier corresponding position of frequency range is 0.
In one embodiment, the OFDM modulation unit, including IFFT module and plus cyclic prefix CP (Cyclic
The frequency-region signal that subcarrier mapping unit is sent is transformed to time-domain signal by Prefix) module, IFFT module；Add cyclic prefix CP
Module adds cyclic prefix CP before each time-domain signal.
In one embodiment, the light emitting and receiving unit include the light load that serial signal is modulated to corresponding frequencies
On wave, injection fibre is transmitted, and receiving end is detected by photoelectric detector and received.Optical modulator used can use intensity
Modulation system, such as Mach increase Dare (MZM, Mach-Zehnder modulator) modulator or reactance modulation system, than
As directly modulated laser (DML, direct modulation laser).
In one embodiment, the OFDM demodulation unit includes: removal cyclic prefix CP module and FFT module, FFT mould
Time domain OFDM signal is reverted to frequency domain ofdm signal by block；Removal cyclic prefix CP module removes following for each time domain OFDM signal
Ring prefix CP.
In one embodiment, the channel estimating unit, by the pilot tone X saved in transmitting terminal, and in receiving end
Taken pilot tone calculates frequency transfer function according to formula, to each by the frequency-region signal Y obtained after transmission and respective handling
Each summation that pilot tone calculates is averaged, and obtains the estimated value as entire channel frequency transition function.It is possible thereby to root
The signal value of transmitting terminal respective frequencies point is recovered according to formula.
According to the mapping ruler in transmitting terminal subcarrier mapping unit, polarization code coding and the number after high order modulation are reverted to
According to format.
In one embodiment, the high-order de-mapping unit, according to Bayesian formula, calculating user information is 0 and 1
Corresponding posterior probability sequence, as rear class polarization code decoding input.
In one embodiment, the polarization code decoding unit, according to the posterior probability sequence of input and known pole
Change the channel information (channel set of transmission fixed bit sequence and information bit sequence) in code cataloged procedure, it can be using string
Row offsets decoding SC method, can also be using improved SC interpretation methods such as SCL decodings, or uses BP, other decodings such as LP
Method, to improve the accuracy rate of decoding.
It is corresponding with above system, a kind of light ofdm signal coded modulation and demodulation method based on polarization code, including such as
Lower step:
Polarization code coding step, needed for being encoded into the user information for needing to transmit by the coding rule of polarization code
The code word of transmission；
High-order mapping step carries out high-order mapping for the code word after encoding polarization code, is mapped on planisphere；
Signal after high-order maps is mapped on available subcarrier by subcarrier maps step；
Pilot tone step is taken, takes pilot tone every a certain number of frequency domain ofdm signals according to Block-type pilot structure, is used for the later period
Channel estimation.
OFDM modulation step carries out IFFT transformation, the frequency domain ofdm signal of subcarrier maps step is converted to time domain
Ofdm signal is transmitted, and adds cyclic prefix CP before each time domain OFDM signal；
Light emitting and receiving step, for the time domain OFDM signal of OFDM modulation step to be modulated to light carrier, in light
It transmits in minute matter, is received in receiving end with photodetector；
OFDM demodulation step removes the cyclic prefix CP of each time domain OFDM signal, and carries out FFT to the data of removal CP
Operation, operation result are used for later period channel estimation；
Channel estimation steps, by the pilot tone X saved in transmitting terminal, and the taken pilot tone in receiving end by transmission and
The frequency-region signal Y obtained after respective handling calculates frequency transfer function according to formula, and each summation calculated each pilot tone takes
It is average, the estimated value as entire channel frequency transition function is obtained, recovers the corresponding frequency of transmitting terminal thus according to formula
The signal value of rate point；
Subcarrier recovering step, after the frequency domain ofdm signal for restoring signal estimating step reverts to high-order mapping
Signal format；
Higher-order solutions mapping step, for the frequency-region signal after restoring subcarrier by soft de-mapped at posterior probability sequence
Column, convenient for the decoding of subsequent polarization code；
Polarization code decoding procedure, the posterior probability sequence for generating higher-order solutions mapping step are produced by polarization code decoding
Raw original user's sequence, completes final transmission.
The technology pair of the above-mentioned light ofdm signal coded modulation based on polarization code and each step specific implementation of demodulation method
Each unit technology of light ofdm signal coded modulation and demodulating system of the Ying Yu based on polarization code, repeats no more again.
Embodiment in detail below is provided according to the above method and system:
In one embodiment, polarization code is selected to encode code length N=512, polarization code code rate R=0.5.Polarization code is believed when encoding
The mode that road is selected selects Pasteur's parametric method, and initial probability of erasure is 0.5.Ofdm signal one shares 512 subcarriers, wherein can
Data subcarrier is 120.The points of IFFT and FFT are 512 points.The order of QAM high-order mapping is 16.Optical fiber transmission
Length is 50Km.
The information bit for needing to transmit is generated by user first, then polarization code coding, warp are carried out by polarization code coding unit
Polarization code encodes the latter symbol and is made of the information bit of 512 0 or 1.
Polarization code sign after each coding is carried out to the high-order mapping of 16QAM, mapping mode selects gray mappings, so that
If the mistake of only one most bit when being finally judged as consecutive points in demodulation, as much as possible the reduction bit error rate.Each symbol
Number it is the data point of 128 plural forms after 16QAM high order modulation, is referred to as a user information symbol.
User symbol after high-order maps is mapped in available frequency sub-carrier.Here Hermitian conjugate pair is used
The mapping mode of title, it is therefore an objective to so that the signal after postmenstruation IFFT is real number.It, will according to the mapping mode of data to subcarrier
Each data point of a user information symbol after high-order mapping is mapped to different sub-carrier positions up in order.At this
In embodiment, specific mapping ruler is as follows: due to now with 512 subcarriers, but the son that can be used for transmission information carries
Wave number amount is 120 therein.The 1st subcarrier and the 257th subcarrier known to the symmetrical mapping mode of Hermitian conjugate
The data of upper storage are zero, and the data stored on remaining sub-carriers claim respectively about the 257th subcarrier conjugate pair.Therefore by the
First complex data point of one user information symbol is stored in the position of the 256th subcarrier, the position of the 258th subcarrier
The conjugate form for storing the complex data point is set, and so on, since available subcarrier only has 120, remove most intermediate
257th subcarrier needs to put zero, and the sub-carrier number that complementary energy puts data shares 119, therefore from the 256th subcarrier to
138 subcarriers store corresponding complex data point, and the 258th to the 376th subcarrier stores the conjugate form of data.Remaining
The subcarrier corresponding position for not transmitting information is zero.Thereby produce the OFDM frequency domain symbol for there are 512 subcarriers to constitute.
Since a user information symbol is made of 128 complex data points, and an OFDM frequency domain symbol has only used 119 here
Data point, remaining 9 complex datas point with regard to being put into next OFDM frequency domain symbol naturally.And next OFDM frequency domain symbol
In remaining available subcarrier continue to store the complex data point of next user information symbol.It, can according to above-mentioned mapping ruler
S OFDM frequency domain symbol is obtained, wherein each OFDM frequency domain symbol includes 512 subcarrier datas, effective data subcarrier
Size for the 138th to the 256th, S is determined by the quantity of user information symbol.
It takes an OFDM frequency domain symbol to save every 20 S OFDM frequency domain symbol of above-mentioned generation to believe as pilot tone
Number, it is used as receiving end channel estimation.Specific rules are to take the 1st, 21,41,61 ... etc. to be used as pilot signal.
The IFFT transformation that S OFDM frequency domain symbol of above-mentioned generation is made to 512 points, is changed into S OFDM for frequency-region signal
Time-domain symbol, to could be transmitted in actual communication system.
The information intersymbol interference as caused by dispersion and inter-carrier interference in transmission process in order to prevent, it is necessary to each
Cyclic prefix CP is added before OFDM time-domain symbol, it is assumed herein that the length of CP is the 25% of OFDM time-domain symbol length.Therefore real
128 time domain sampling points at each OFDM time-domain symbol end can be taken out by applying in example is put into the front, so that 512 of script
OFDM time-domain symbol becomes 640 OFDM time-domain symbols.
Parallel/serial conversion is carried out to signal, i.e., above-mentioned S 640 OFDM time-domain symbols joins end to end, becomes containing
There is the time-domain signal of S*640 sampled point.
Since in systems in practice, the initial position of receiving end signal is unknown, it is therefore necessary to before the signal of transmitting terminal
Clock synchronizing sequence is added in face, and 0, the 1 bit m-sequence that length is 127 is added herein.In order to the signal amplitude that actually sends
On be consistent, will be added clock synchronizing sequence each bit multiplied by OFDM time-domain signal sampled point maximum value.
The OFDM time-domain sampling signal containing S*640+127 time domain sampling point is thereby produced, wherein preceding the 127 of signal
A sampled point is clock synchronizing sequence, does not carry any information.Every 640 sampled points are one group since the 128th sampled point,
It is an OFDM time-domain symbol.Wherein preceding 128 sampled points are the cyclic prefix being added in each 640 OFDM time-domain signals.
The Transmission system used herein is the optical transmission system of carrier wavelength 1550nm, rate of information throughput 10Gbit/
S, the fiber lengths used is 50Km.It is corresponding by generating the serial time domain sampled signal of above-mentioned generation by MZM modulation
Optical signal, the optical fiber transmission by 50Km length generate suitable optical power for receiving by optical attenuator.In receiving end benefit
The optical signal received electric signal is converted to photodetector to store.
Since transmitting terminal is the time-domain sampling signal for cycling through a succession of OFDM, the data that receiving end receives
It is circulation, the initial position of signal is unknown.Therefore the clock synchronizing sequence joined the data received and early period is made
The convolution algorithm of cyclic shift, according to the property of clock synchronizing sequence itself it is found that when peak value occurs in convolution algorithm result, just
It is the convolution algorithm result of clock synchronizing sequence and itself.Therefore, in a series of cyclic shift convolution algorithm results of acquirement
Peak value at can be determined that it is added clock synchronizing sequence, it be backward signal initial position.
Since the original position of signal, taking the S*640 data points received is that transmitted OFDM time domain is adopted
Sample sequence recovers each OFDM time-domain symbol before sending then again with 640 data points for one group of carry out serial/parallel conversion.
According to front plus each ofdm signal of cyclic prefix effective information position be the 129th to the 640th altogether 512
A data point, preceding 128 data points are added cyclic prefix CP.Therefore effective 512 sampled points are made at 512 points respectively
FFT transform recovers the frequency-region signal of OFDM a series of.
Since, into MZM modulation, optical fiber transmission is crossed, optical attenuator controls power and photodetector in signals transmission
It is received, the frequency characteristic of entire channel is not a horizontal straight line, i.e., the amplitude-frequency characteristic H of each frequency point is not
With, therefore channel estimation must be just carried out to recover original signal.By the pilot tone X saved in transmitting terminal, and connecing
The taken pilot tone of receiving end calculates frequency transfer function according to formula by the frequency-region signal Y obtained after transmission and respective handling, right
Each frequency transfer function summation that each pilot tone calculates is averaged, and obtains estimating as entire channel frequency transition function
Evaluation.It is possible thereby to recover the signal value of transmitting terminal respective frequencies point according to formula.Thus the S of transmitting terminal transmission has been recovered
The frequency domain symbol of a OFDM.
According to the mapping relations of Primary Stage Data to subcarrier, user information symbol is recovered from the frequency domain symbol of S OFDM
Number.Each user information symbol contains 128 complex data points.
The user information symbol recovered is subjected to the soft demodulation of 16QAM, when exporting each user's bit transfer 0 and 1 after
Test probability.Specific each user information symbol contains 128 complex data points, includes 512 bits of user data.Therefore
What is exported after the soft demodulation of 16QAM is that the posterior probability that 512 user's bits are 0 and the posteriority that 512 user's bits are 1 are general
Rate.
By above-mentioned posterior probability sequence inputting to polarization code decoding unit, the SCL decoding of polarization code, searching route number are carried out
L takes 1,2,4, so that receiving end be made to obtain the original user data bit of transmitting terminal transmission.Specific ber curve is shown in Fig. 3.
The introducing of the bit error rate of whole system when Fig. 3 also compared being not added polarization code simultaneously, comparison discovery polarization code is largely dropped
The low bit error rate of whole system, improves system performance.
Above-described embodiment is had as follows using light ofdm signal coded modulation and demodulating system and method based on polarization code
Advantage:
1. polarization code is as a kind of channel coding algorithm that can reach Shannon tolerance and have lower encoding and decoding complexity, drop
The bit error rate in low message transmitting procedure, improves the reliability of system.
2. the introducing of high-order mapping improves the information content that single symbol carries, the data transmission of optical communication system is improved
Rate.
3. smooth OFDM modulation is so that whole system has preferable mitigating frequency-selective fading and narrow-band characteristic.It can spirit
The lesser subcarrier of selection decaying living carries out data transmission, while signal is concentrated in a narrow band signal, effectively solves frequency
The limited problem of spectrum resource, improves the band efficiency of system.
Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned
Particular implementation, those skilled in the art can make a variety of changes or modify within the scope of the claims, this not shadow
Ring substantive content of the invention.
Claims (8)
1. a kind of light ofdm signal coded modulation and demodulating system based on polarization code, which is characterized in that the system comprises:
Polarization code coding unit, for the user information for needing to transmit to be encoded into required transmission by the coding rule of polarization code
Code word；
High-order map unit carries out high-order mapping for the code word after encoding polarization code, is mapped on planisphere；
Signal after high-order maps is mapped on available subcarrier by subcarrier mapping unit in order；
Pilot cell is taken, takes pilot tone every a certain number of frequency domain ofdm signals according to Block-type pilot structure, is used for later period channel
Estimation；
OFDM modulation unit carries out IFFT transformation, and the frequency domain ofdm signal that subcarrier mapping unit transmits is converted to time domain
Ofdm signal is transmitted, and adds cyclic prefix CP before each time domain OFDM signal；
Light emitting and receiving unit, the time domain OFDM signal for sending OFDM modulation unit is modulated to light carrier, in light
It transmits in minute matter, is received in receiving end with photodetector；
OFDM demodulation unit removes the cyclic prefix CP of each time domain OFDM signal, and carries out FFT fortune to the data of removal CP
It calculates, operation result is used for later period channel estimation；
Channel estimating unit is connected with the input terminal of the output end of OFDM demodulation unit, subcarrier recovery unit, for by
The pilot tone X that transmitting terminal saves, and the frequency-region signal Y obtained after the taken pilot tone in receiving end is by transmission and respective handling,
Frequency transfer function is calculated according to formula, each frequency transfer function summation that each pilot tone calculates is averaged, conduct is obtained
The estimated value of entire channel frequency transition function, the signal value of transmitting terminal respective frequencies point is recovered thus according to formula；
Subcarrier recovery unit, frequency domain ofdm signal for restoring signal estimation unit by subcarrier maps rule it is counter push away it is extensive
Signal format after being mapped again at high-order；
High-order de-mapping unit, for the frequency-region signal after restoring subcarrier by soft de-mapped at posterior probability sequence, just
In the decoding of subsequent polarization code；
Polarization code decoding unit, the posterior probability sequence for generating high-order de-mapping unit generate former by polarization code decoding
User's sequence of beginning, completes final transmission.
2. the light ofdm signal coded modulation and demodulating system according to claim 1 based on polarization code, which is characterized in that
The polarization code coding unit selects suitable polarization code coding code length N and code rate R, the integer that wherein code length N is 2
Power, and according to code length N and code rate R selection information channel and fixed bit channel.
3. the light ofdm signal coded modulation and demodulating system according to claim 1 based on polarization code, which is characterized in that
The binary bit sequence that polarization code coding generates is mapped to accordingly by the high-order map unit with the method that high-order maps
Each point on planisphere.
4. the light ofdm signal coded modulation and demodulating system according to claim 1 based on polarization code, which is characterized in that
Each data point of a frame data after high-order maps is mapped to different by the subcarrier mapping unit in order
Sub-carrier positions get on, and specific mapping ruler is as follows: the frame data format after high-order mapping is X1,X2,…XN/m, N is pole
Change the code length of code, m is the order of high-order mapping, and available subcarrier is U in an ofdm signalp,Up+1,…Uq, p is available son
The start sequence number of carrier wave, q are the termination serial number of available subcarrier, and the sum of available subcarrier is q-p+1, according to numeric order
By X1It is mapped to U1, by X2It is mapped to U2, and so on；If available subcarrier number q-p+1 is less than the data length N/ of a frame data
The data of beginning are then mapped on the available subcarrier of next ofdm signal by m in order；If available subcarrier number q-p+1
Greater than the data length N/m of a frame data, then the data after the mapping of next frame high-order are mapped in order on remaining subcarrier；
If there is the case where complex data point after modulator approach modulation, level is corresponded to by subcarrier by the symmetrical mode of Hermitian conjugate
On, the subcarrier corresponding position for the frequency range not used is 0.
5. the light ofdm signal coded modulation and demodulating system according to claim 1 based on polarization code, which is characterized in that
The OFDM modulation unit, including IFFT module and plus cyclic prefix CP module, IFFT module sends out subcarrier mapping unit
The frequency-region signal sent is transformed to time-domain signal；Add cyclic prefix CP module before each time-domain signal plus cyclic prefix CP.
6. the light ofdm signal coded modulation and demodulating system according to claim 1 based on polarization code, which is characterized in that
The OFDM demodulation unit includes: that removal cyclic prefix CP module and FFT module, FFT module restore time domain OFDM signal
At frequency domain ofdm signal；Removal cyclic prefix CP module removes the cyclic prefix CP of each time domain OFDM signal.
7. the light ofdm signal coded modulation and demodulating system according to claim 1 based on polarization code, which is characterized in that
The high-order de-mapping unit calculates the corresponding posterior probability sequence that user information is 0 and 1 according to Bayesian formula, makees
For the input of rear class polarization code decoding.
8. a kind of light ofdm signal coded modulation and demodulation based on polarization code using any one of the claim 1-7 system
Method characterized by comprising
Polarization code coding step, for the user information for needing to transmit to be encoded into required transmission by the coding rule of polarization code
Code word；
High-order mapping step carries out high-order mapping for the code word after encoding polarization code, is mapped on planisphere；
Signal after high-order maps is mapped on available subcarrier by subcarrier maps step；
Pilot tone step is taken, takes pilot tone every a certain number of frequency domain ofdm signals according to Block-type pilot structure, is used for later period channel
Estimation；
OFDM modulation step carries out IFFT transformation, and the frequency domain ofdm signal of subcarrier maps step is converted to time domain OFDM letter
It number is transmitted, and before each time domain OFDM signal plus cyclic prefix CP；
Light emitting and receiving step are situated between for the time domain OFDM signal of OFDM modulation step to be modulated to light carrier in optical fiber
It transmits in matter, is received in receiving end with photodetector；
OFDM demodulation step removes the cyclic prefix CP of each time domain OFDM signal, and carries out FFT fortune to the data of removal CP
It calculates, operation result is used for later period channel estimation；
Channel estimation steps pass through transmission and corresponding by the pilot tone X saved in transmitting terminal, and in the taken pilot tone in receiving end
The frequency-region signal Y obtained after processing calculates frequency transfer function according to formula, and each summation calculated each pilot tone is made even
, the estimated value as entire channel frequency transition function is obtained, recovers transmitting terminal respective frequencies thus according to formula
The signal value of point；
Subcarrier recovering step, the frequency domain ofdm signal for restoring signal estimating step revert to the signal after high-order mapping
Format；
Higher-order solutions mapping step, for the frequency-region signal after restoring subcarrier by soft de-mapped at posterior probability sequence, just
In the decoding of subsequent polarization code；
Polarization code decoding procedure, the posterior probability sequence for generating higher-order solutions mapping step generate former by polarization code decoding
User's sequence of beginning, completes final transmission.
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Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106788724A (en) * | 2016-12-09 | 2017-05-31 | 暨南大学 | A kind of visible light communication system and its implementation based on polarization code |
| CN107070822B (en) * | 2017-05-11 | 2019-07-23 | 安徽大学 | A kind of polarization code frequency pilot sign choosing method |
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| CN107682121B (en) * | 2017-10-16 | 2021-04-27 | 中国科学院微电子研究所 | Coding method and device |
| CN109756438B (en) * | 2019-02-01 | 2021-06-29 | 华侨大学 | OOFDM method and system based on LDPC coding probability shaping mapping |
| CN111600679B (en) * | 2020-02-24 | 2021-11-02 | 北京交通大学 | Optical communication system based on polarization interleaving |
| CN113746768B (en) * | 2021-09-16 | 2024-03-01 | 厦门纵行信息科技有限公司 | Low-power consumption frequency point index modulation method, transmitter and receiver thereof |
| CN113992305A (en) * | 2021-12-28 | 2022-01-28 | 南京信息工程大学 | Pilot insertion method, optical communication method, readable storage medium, and computing device |
| CN114978838B (en) * | 2022-05-11 | 2024-05-14 | 华中科技大学 | Anti-harmonic interference polar code modulation method |
| CN114978314B (en) * | 2022-05-24 | 2023-05-16 | 福建工程学院 | Visible light communication transmission method combining incoherent frequency-time coding with DCO-OFDM |
| CN115102616A (en) * | 2022-05-29 | 2022-09-23 | 复旦大学 | Underwater wireless green light communication transmission system based on plastic optical fiber extension communication link |
| CN115549861B (en) * | 2022-09-20 | 2023-05-09 | 广东工业大学 | Bit interleaving method and device based on visible light communication |
| CN115296750B (en) * | 2022-09-28 | 2023-01-17 | 鹏城实验室 | Underwater acoustic communication system for constructing polarization code based on Gaussian approximation improvement method |
| CN115314124B (en) * | 2022-09-28 | 2023-01-10 | 鹏城实验室 | Polar code construction method, system and device |
| CN118101075B (en) * | 2024-04-24 | 2024-07-05 | 紫金山实验室 | OFDM modulation method, device, equipment, medium and product based on mixed constellation shaping |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101043485A (en) * | 2006-03-22 | 2007-09-26 | 松下电器产业株式会社 | Transmission method, reception method and equipment and communication system |
| CN101119178A (en) * | 2006-08-01 | 2008-02-06 | 华为技术有限公司 | Signal transmitting, receiving method and signal transmitting device |
| CN101394392A (en) * | 2008-11-12 | 2009-03-25 | 北京邮电大学 | Signal diversifying method for OFDM system |
| CN103023618A (en) * | 2013-01-11 | 2013-04-03 | 北京邮电大学 | Random code length polar encoding method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8184993B2 (en) * | 2009-02-25 | 2012-05-22 | Nec Laboratories America, Inc. | Polarization mode dispersion (PMD) compensation in polarization multiplexed coded orthogonal frequency division multiplexing (OFDM) systems |
-
2016
- 2016-06-16 CN CN201610430660.2A patent/CN106130656B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101043485A (en) * | 2006-03-22 | 2007-09-26 | 松下电器产业株式会社 | Transmission method, reception method and equipment and communication system |
| CN101119178A (en) * | 2006-08-01 | 2008-02-06 | 华为技术有限公司 | Signal transmitting, receiving method and signal transmitting device |
| CN101394392A (en) * | 2008-11-12 | 2009-03-25 | 北京邮电大学 | Signal diversifying method for OFDM system |
| CN103023618A (en) * | 2013-01-11 | 2013-04-03 | 北京邮电大学 | Random code length polar encoding method |
Non-Patent Citations (2)
| Title |
|---|
| Mapping Selection and Code Construction for 2m-ary Polar-Coded Modulation;Dong-Min Shin等;《IEEE COMMUNICATIONS LETTERS》;20120417;第16卷(第6期);第1-4页 |
| Polar码在OFDM系统中应用研究;郑芝芳等;《电子测试》;20120701(第4（2012）期);第1-4页 |
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