CN112312239B - Preamble design method and system for uplink burst mode in coherent PON - Google Patents
Preamble design method and system for uplink burst mode in coherent PON Download PDFInfo
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Abstract
The invention discloses a lead code design method and a lead code design system for an uplink burst mode in a coherent PON, which relate to the field of optical access networks, wherein the method comprises the steps of constructing a lead code structure, wherein the constructed lead code comprises a clock recovery sequence, a frame synchronization and ONU mark sequence and a channel estimation sequence; the OLT receives the DSP and performs clock recovery based on a clock recovery sequence; based on the sliding window, multiplying the symbol with the preset number at the front section by the synchronous sequence code, and then carrying out autocorrelation on the result with the symbol with the same preset number at the rear section to obtain a frame synchronization and synchronous head of an ONU mark sequence; based on frame synchronization and the number symbols set at the front section of the initial position of the ONU mark sequence, after multiplying the identifier of each ONU, the current ONU is identified by the maximum value obtained by self-correlation with the same preset number symbols at the rear section. The invention realizes the effective identification of the ONU by sharing the lead code for a plurality of DSP functions and identifying the ONU serial number in the lead code.
Description
Technical Field
The invention relates to the field of optical access networks, in particular to a lead code design method and a lead code design system for an uplink burst mode in a coherent PON.
Background
The bandwidth demand of optical access networks has increased dramatically in recent years driven by 5G mobile internet, cloud technology and high definition video streaming services. The demand that the transmission rate of PON (Passive Optical Network) reaches 25Gb/s, 50Gb/s and even 100Gb/s is also scheduled. Due to limited power budget and complex wavelength resource management, the direct alignment detection scheme using multi-channel multiplexing is challenging, and a single-wavelength TDM (Time-division multiplexing) coherent PON is an attractive solution. Due to high sensitivity and the advancement of DSP (Digital Signal processing), coherent PONs can provide higher access capacity and longer coverage. However, there still exist some challenges with this scheme, and one of the key issues is how to efficiently and reliably implement coherent detection of uplink burst mode.
The traditional point-to-point continuous mode coherent detection is mainly based on blind equalization or feedback equalization, and is not suitable for burst mode detection because the signal recovery needs a long acquisition time. For 100G TDM coherent PON uplink transmission, preamble design and burst mode signal processing performance are particularly important, and it is necessary to reduce preamble length and optimize and improve transmission efficiency. The preamble functions as a training sequence for clock recovery, burst frame synchronization, depolarisation multiplexing and channel estimation. For a conventional equalizer, if LMS (Least Mean Square) is used, it generally requires thousands of training sequence symbols to converge. However, if the MEM equalization scheme with pre-stored equalization coefficients is adopted, the convergence time can be greatly shortened, but for the uplink TDM transmission of the PON, in the case that data is not recovered, how to identify an ONU (Optical Network Unit) at an OLT (Optical line terminal) end is needed to solve, so as to use the pre-stored coefficients corresponding to the ONU.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method and a system for designing a preamble code of an uplink burst mode in a coherent PON.
In order to achieve the above object, the present invention provides a preamble design method for an uplink burst mode in a coherent PON, comprising the following steps:
constructing a lead code structure, wherein the constructed lead code comprises a clock recovery sequence, a frame synchronization and ONU mark sequence and a channel estimation sequence;
the OLT receives the DSP and performs clock recovery based on a clock recovery sequence;
based on the sliding window, multiplying the symbol with the preset number at the front section by the synchronous sequence code, and then carrying out autocorrelation on the result with the symbol with the same preset number at the rear section to obtain a frame synchronization and synchronous head of an ONU mark sequence;
based on frame synchronization and the number symbols set at the front section of the initial position of the ONU mark sequence, after multiplying the identifier of each ONU, the current ONU is identified by the maximum value obtained by self-correlation with the same preset number symbols at the rear section.
On the basis of the technical proposal, the device comprises a shell,
the ONU identifier is a 128-bit binary sequence, and each ONU corresponds to a different ONU identifier;
the synchronization sequence code is a binary sequence of 256 bits, and each ONU adopts the same synchronization sequence code.
On the basis of the technical proposal, the device comprises a shell,
the OLT end receives the DSP and performs burst clock recovery by using 1024 random QPSK symbols forming a clock recovery sequence in the lead code;
the OLT end receives the DSP and performs frame synchronization, depolarization multiplexing, frequency offset estimation and ONU identification by using 512 QPSK symbols forming a frame synchronization and ONU mark sequence in the lead code;
and the OLT receives the DSP and performs channel equalization by using 128 random QPSK symbols forming a channel estimation sequence in the lead code.
On the basis of the technical proposal, the device comprises a shell,
calculating a depolarization multiplexing matrix and frequency offset by using 128 QPSK symbols forming a first part of a frame synchronization and ONU mark sequence;
identifying a current ONU by using 128 QPSK symbols constituting a second part of the frame synchronization and ONU marker sequence, wherein the second part is obtained based on a product of the first part and an ONU identifier;
and searching a synchronization head by using 256 QPSK symbols forming a third part of the frame synchronization and ONU marker sequence, wherein the third part is obtained based on the product of the first part and the second part which are combined and multiplied by a 256-length synchronization sequence code.
On the basis of the above technical solution, the synchronization header of the frame synchronization and the ONU tag sequence is obtained by multiplying the pre-set number symbol of the front segment by the sync sequence code and then by auto-correlating the pre-set number symbol of the rear segment with the sync sequence code based on the sliding window, wherein the formula used for auto-correlating the pre-set number symbol of the front segment by the sync sequence code is as follows:
wherein r is x,y Comprising r x And r y ，r x Received symbols representing X polarization, r y A received symbol representing Y polarization, a conjugate symbol, C x,y (m) represents the result of the autocorrelation multiplied by the synchronization sequence code, N represents the number 128, SYN represents the synchronization sequence code, m represents the mth symbol, and k represents k data from 0 to 2N-1 after the m symbols.
On the basis of the technical scheme, the number symbol is set at the front section based on the frame synchronization and the initial position of the ONU mark sequence, after the multiplication with the identifier of each ONU, the autocorrelation is carried out with the same preset number symbol at the rear section, and the obtained maximum value identifies the current ONU, wherein the number symbol is set at the front section based on the frame synchronization and the initial position of the ONU mark sequence, after the multiplication with the identifier of each ONU, the autocorrelation is carried out with the same preset number symbol at the rear section, and the used formula is as follows:
wherein p represents the serial number of the ONU, and p is a positive integer, ONUid [p] The identifier of the ONU with the serial number p is shown, h shows the frame synchronization and the initial position of the ONU mark sequence, U (p) shows the result of the autocorrelation of the first 128 symbols of the frame synchronization and the initial position of the ONU mark sequence multiplied by the identifier of the ONU with the serial number p and the latter 128 symbols, and N shows the number 128.
On the basis of the above technical solution, in the first part, a sign relationship between X polarization and Y polarization satisfies:
TY[2n]＝±TX[2n]
TY[2n+1]＝±j×TX[2n+1]
wherein, TY takes value 1, j, -1 or j randomly, j is complex unit, n is code element serial number.
On the basis of the above technical solution, while identifying the current ONU, the method further includes:
using the frame sync and the first part of the ONU mark sequence to perform a depolarization matrix [ a, B; -B, a ] by the formula:
r x ×(r y ) * ＝±(A 2 -B 2 ) When TY ± + -TX
r x ×(r y ) * ＝mj(A 2 -B 2 ) When TY is + -jTX
Wherein r is x Received symbols representing X polarization, r y The received symbol representing the Y polarization, indicates the conjugate symbol.
On the basis of the technical scheme, after the completion of the depolarization multiplexing, the frequency offset estimation and the ONU identification, the method further comprises the following steps:
extracting the self-adaptive filter coefficient calculated by the previous frame data from the register, and taking the extracted self-adaptive filter coefficient as an initial coefficient of the self-adaptive filter;
and adopting a CMA adaptive equalization algorithm, performing channel estimation by using a channel estimation sequence, and storing the coefficient of the current adaptive equalizer into a local corresponding register.
The invention provides a lead code design system for an uplink burst mode in a coherent PON, which comprises the following steps:
the system comprises a construction module, a channel estimation module and a clock recovery module, wherein the construction module is used for constructing a lead code structure, and the constructed lead code comprises a clock recovery sequence, a frame synchronization and ONU mark sequence and a channel estimation sequence;
the recovery module is used for performing clock recovery based on the clock recovery sequence when the OLT receives the DSP;
the calculation module is used for multiplying the symbol with the preset number at the front section by the synchronous sequence code based on the sliding window and then carrying out self-correlation on the result with the symbol with the preset number at the rear section to obtain a frame synchronization and an ONU mark sequence synchronization head;
and the identification module is used for setting number symbols on the front section of the frame synchronization and the initial position of the ONU marking sequence, multiplying the number symbols by the identifier of each ONU, then performing self-correlation on the number symbols which are the same as the preset number symbols on the rear section, and identifying the current ONU according to the obtained maximum value.
Compared with the prior art, the invention has the advantages that: by adopting the reconstructed lead code structure design and combining the equalization coefficient pre-storage method, the synchronization and equalization convergence time of the uplink transmission data of each ONU at the OLT receiving end is greatly reduced, the communication efficiency is effectively improved, and meanwhile, the serial number of the ONU is identified in the lead code by sharing the lead code for a plurality of DSP functions, so that the effective identification of the ONU is realized.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a flowchart of a preamble design method for an uplink burst mode in a coherent PON according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating the structure of the X polarization of the preamble in the embodiment of the present invention;
FIG. 3 is a diagram illustrating the structure of the Y polarization of the preamble in the embodiment of the present invention;
fig. 4 is a schematic structural diagram of a preamble design method for an uplink burst mode in a coherent PON according to an embodiment of the present invention.
Detailed Description
The embodiment of the invention provides a lead code design method for an uplink burst mode in a coherent PON, which adopts a reconstructed lead code structure design and combines a method of equalizing coefficient pre-storage, so that the synchronization and equalizing convergence time of uplink burst data of each ONU at an OLT receiving end is greatly reduced, and the communication efficiency is effectively improved. The embodiment of the invention correspondingly provides a lead code design system for the uplink burst mode in the coherent PON.
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, a preamble design method for an uplink burst mode in a coherent PON according to an embodiment of the present invention includes the following steps:
s1: and constructing a lead code structure, wherein the constructed lead code comprises a clock recovery sequence, a frame synchronization and ONU mark sequence and a channel estimation sequence.
In the embodiment of the present invention, the OLT receives the DSP, and performs burst clock recovery by using 1024 random QPSK symbols constituting a clock recovery sequence in the preamble, where the clock recovery sequence is composed of 1024 random QPSK (Quadrature Phase Shift Keying) symbols, and specifically, the clock recovery sequence may be composed of 1024 random QPSK symbols which are approximately uniformly distributed. And the OLT end receives the DSP and performs frame synchronization, depolarization multiplexing, frequency offset estimation and ONU identification by using 512 QPSK symbols forming a frame synchronization and ONU mark sequence in the lead code, wherein the frame synchronization and ONU mark sequence is formed by 512 QPSK symbols. The OLT receives the DSP, and performs channel equalization by using 128 random QPSK symbols forming a channel estimation sequence in the preamble, wherein the channel estimation sequence is formed by 128 random QPSK symbols.
In the embodiment of the invention, the frame synchronization and ONU mark sequence comprises a first part, a second part and a third part, wherein the first part comprises 128 QPSK symbols, the second part comprises 128 QPSK symbols, and the third part comprises 256 QPSK symbols. The calculation of the matrix and frequency offset for the de-polarization multiplexing is performed using 128 QPSK symbols forming the first part of the frame synchronization and ONU tag sequence, which can be defined as S x/y In the first section, the sign relationship of the X-polarization and the Y-polarization satisfies:
TY[2n]＝±TX[2n]
TY[2n+1]＝±j×TX[2n+1]
wherein, TY takes value 1, j, -1 or j randomly, j is complex unit, n is code element serial number.
Using 128 QPSK symbols forming the second part of the frame synchronization and ONU mark sequence to identify the current ONU, the second part is obtained based on the product of the first part and the ONU identifier, namely the second part can be expressed as Sx/y ONUid [p] P represents the serial number of ONU, and p is a positive integer, ONUid [p] Indicating the identifier of the ONU with sequence number p. Using 256 QPSK symbols forming the third part of frame synchronization and ONU mark sequence to search the synchronization head, the third part is obtained based on the product of the first part and the second part which are combined and multiplied by the 256 length synchronization sequence code, the third part can be expressed as [ sx/y, sx/y ONUid [p] ]SYN. So the frame synchronization and ONU tag sequences for both polarizations can be expressed as: [ Sx, Sx ONUid [ ] [p] ,[Sx,Sx*ONUid [p] ]*SYN]And [ Sy, Sy ONUid [p] ,[Sy,Sy*ONUid [p] ]*SYN]For the preamble, the structure diagram of the X polarization is shown in fig. 2, the structure diagram of the Y polarization is shown in fig. 3, where a1 represents a clock recovery sequence, a2 represents a frame synchronization and ONU flag sequence, and A3 represents a channel estimation sequence.
S2: the OLT receives the DSP and performs clock recovery based on a clock recovery sequence;
s3: based on a sliding window, multiplying a front-section preset number symbol by a synchronous sequence code, and then performing autocorrelation on a result of the front-section preset number symbol to obtain a frame synchronization and an ONU mark sequence synchronization head;
in the embodiment of the present invention, based on the sliding window, the frame synchronization and the synchronization header of the ONU tag sequence are obtained by multiplying the pre-determined number symbol of the front segment by the synchronization sequence code, and then performing autocorrelation on the pre-determined number symbol of the rear segment, where the formula used for autocorrelation on the pre-determined number symbol of the front segment by the synchronization sequence code is as follows:
wherein r is x,y Comprising r x And r y ，r x Represents X biasReceived sign of vibration, r y A received symbol representing Y polarization, a conjugate symbol, C x,y (m) represents the result of the autocorrelation multiplied by the synchronization sequence code, N represents the number 128, SYN represents the synchronization sequence code, m represents the mth symbol, and k represents k data from 0 to 2N-1 after the m symbols.
That is, using a sliding window, taking m as a starting point, multiplying 256 symbols at the front section by a synchronization sequence code, and then performing autocorrelation on the result with 256 symbols at the rear section, thereby finding the position of a synchronization header for obtaining frame synchronization and an ONU mark sequence with respect to the maximum value.
S4: based on frame synchronization and the number symbols set at the front section of the initial position of the ONU mark sequence, after multiplying the identifier of each ONU, the current ONU is identified by the maximum value obtained by self-correlation with the same preset number symbols at the rear section. In the embodiment of the invention, the ONU identifier is a 128-bit binary sequence, and each ONU corresponds to a different ONU identifier; the synchronization sequence code is a binary sequence of 256 bits, and the synchronization sequence code of each ONU is the same.
In the embodiment of the invention, the number symbols are set at the front section of the initial position of the frame synchronization and ONU marking sequence, after the multiplication with the identifier of each ONU, the autocorrelation is carried out with the same preset number symbols at the rear section, and the obtained maximum value identifies the current ONU, wherein, the number symbols are set at the front section of the initial position of the frame synchronization and ONU marking sequence, after the multiplication with the identifier of each ONU, the autocorrelation is carried out with the same preset number symbols at the rear section, and the used formula is as follows:
wherein p represents the serial number of the ONU, and p is a positive integer, ONUid [p] The identifier of the ONU with the serial number p is shown, h shows the frame synchronization and the initial position of the ONU mark sequence, U (p) shows the result of the autocorrelation of the first 128 symbols of the frame synchronization and the initial position of the ONU mark sequence multiplied by the identifier of the ONU with the serial number p and the latter 128 symbols, and N shows the number 128.
That is, after finding the synchronization header, according to the frame synchronization and after multiplying the first 128 symbols of the start position of the ONU tag sequence by the ONU identifier, the autocorrelation result is performed with the last 128 symbols, and the maximum value is found out to obtain the current received ONU serial number.
In the embodiment of the present invention, while identifying the current ONU, the method further includes:
using the frame sync and the first part of the ONU mark sequence to perform a depolarization matrix [ a, B; -B, a ] by the formula:
r x ×(r y ) * ＝±(A 2 -B 2 ) When TY ± + -TX
r x ×(r y ) * ＝mj(A 2 -B 2 ) When TY is + -jTX
Wherein r is x Received symbols representing X polarization, r y The received symbol representing the Y polarization, indicates the conjugate symbol.
After the completion of the polarization demultiplexing, the frequency offset estimation and the ONU identification, the method further comprises the following steps:
extracting the self-adaptive filter coefficient calculated by the previous frame data from the register, and taking the extracted self-adaptive filter coefficient as an initial coefficient of the self-adaptive filter;
and adopting a CMA adaptive equalization algorithm, performing channel estimation by using a channel estimation sequence, and storing the coefficient of the current adaptive equalizer into a local corresponding register. Namely, a CMA adaptive equalization algorithm is adopted, and a channel estimation sequence is used for channel estimation, and the payload processing is started after 128 symbols of the channel estimation sequence.
According to the lead code design method provided by the embodiment of the invention, the lead code frame synchronization and the ONU mark sequence simultaneously complete a plurality of DSP functions of knowing polarization matrix calculation, frequency deviation calculation, head finding, positioning of the ONU and the like, the lead code efficiency is greatly improved, and the lead code length is reduced. Compared with the mode of firstly demultiplexing and then finding the synchronous head, the method can greatly shorten the time of synchronization. Meanwhile, the identification sequence in the frame synchronization and ONU mark sequence extracts the locally pre-stored equalization coefficient corresponding to the ONU, and is directly used for the subsequent adaptive equalization calculation, thereby greatly shortening the convergence time of the adaptive equalizer. Lead code length is reduced by sharing the lead code for a plurality of DSP functions, identifying ONU serial numbers in the lead code and pre-storing equalization coefficients, and transmission efficiency in a burst mode is improved.
The preamble design method for the uplink burst mode in the coherent PON, provided by the embodiment of the invention, adopts a reconstructed preamble structure design and combines an equalization coefficient pre-storage method, so that the synchronization and equalization convergence time of uplink transmission data of each ONU at an OLT receiving end is greatly reduced, the communication efficiency is effectively improved, meanwhile, the preamble is shared by a plurality of DSP functions, the ONU serial number is identified in the preamble, and the equalization coefficient pre-storage method is used for reducing the length of the preamble and improving the transmission efficiency.
Referring to fig. 4, an embodiment of the present invention further provides a preamble design system for an upstream burst mode in a coherent PON, which includes a construction module, a recovery module, a calculation module, and an identification module.
The construction module is used for constructing a lead code structure, and the constructed lead code comprises a clock recovery sequence, a frame synchronization and ONU marking sequence and a channel estimation sequence; the recovery module is used for performing clock recovery based on the clock recovery sequence when the OLT receives the DSP; the calculation module is used for multiplying the symbol with the preset number at the front section by the synchronous sequence code based on the sliding window and then carrying out self-correlation on the result with the symbol with the preset number at the rear section to obtain a frame synchronization and synchronous head of an ONU mark sequence; the identification module is used for setting number symbols on the basis of frame synchronization and the front section of the initial position of the ONU marking sequence, multiplying the number symbols by the identifiers of all the ONUs, then carrying out self-correlation on the number symbols which are the same as the preset number symbols on the rear section, and identifying the current ONU according to the obtained maximum value.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Claims (10)
1. A preamble design method for an uplink burst mode in a coherent PON, comprising the steps of:
constructing a lead code structure, wherein the constructed lead code comprises a clock recovery sequence, a frame synchronization and ONU mark sequence and a channel estimation sequence;
the OLT receives the DSP and performs clock recovery based on a clock recovery sequence;
based on the sliding window, multiplying the symbol with the preset number at the front section by the synchronous sequence code, and then carrying out autocorrelation on the result with the symbol with the same preset number at the rear section to obtain a frame synchronization and synchronous head of an ONU mark sequence;
based on frame synchronization and the number symbols set at the front section of the initial position of the ONU mark sequence, after multiplying the identifier of each ONU, the current ONU is identified by the maximum value obtained by self-correlation with the same preset number symbols at the rear section.
2. The method of claim 1, wherein the preamble design method for uplink burst mode in a coherent PON comprises:
the ONU identifier is a 128-bit binary sequence, and each ONU corresponds to a different ONU identifier;
the synchronization sequence code is a 256-bit binary sequence, and each ONU adopts the same synchronization sequence code.
3. A preamble design method for an uplink burst mode in a coherent PON as claimed in claim 2 wherein:
the OLT end receives the DSP and performs burst clock recovery by using 1024 random QPSK symbols forming a clock recovery sequence in the lead code;
the OLT end receives the DSP and performs frame synchronization, depolarization multiplexing, frequency offset estimation and ONU identification by using 512 QPSK symbols forming a frame synchronization and ONU mark sequence in the lead code;
and the OLT receives the DSP and performs channel equalization by using 128 random QPSK symbols forming a channel estimation sequence in the lead code.
4. A preamble design method for an uplink burst mode in a coherent PON as claimed in claim 3 wherein:
calculating a depolarization multiplexing matrix and frequency offset by using 128 QPSK symbols forming a first part of a frame synchronization and ONU mark sequence;
identifying a current ONU by using 128 QPSK symbols constituting a second part of the frame synchronization and ONU marker sequence, wherein the second part is obtained based on a product of the first part and an ONU identifier;
and searching a synchronization head by using 256 QPSK symbols forming a third part of the frame synchronization and ONU marker sequence, wherein the third part is obtained based on the product of the first part and the second part which are combined and multiplied by a 256-length synchronization sequence code.
5. The method as claimed in claim 4, wherein the sliding window based synchronization header of the frame synchronization and the ONU mark sequence is obtained by multiplying the synchronization sequence code by a pre-determined number of symbols in the front segment and then by auto-correlating with a pre-determined number of symbols in the back segment, wherein the formula used for auto-correlating with the pre-determined number of symbols in the back segment after multiplying the synchronization sequence code by the pre-determined number of symbols in the front segment is as follows:
wherein r is x,y Comprising r x And r y ，r x Received symbols representing X polarization, r y A received symbol representing Y polarization, a conjugate symbol, C x,y (m) represents the result of the autocorrelation multiplied by the synchronization sequence code, N represents the number 128, SYN represents the synchronization sequence code, m represents the mth symbol, and k represents k data from 0 to 2N-1 after the m symbols.
6. The method of claim 4, wherein the current ONU is identified based on a maximum value obtained by multiplying a predetermined number of symbols before the frame synchronization and ONU mark sequence start position by an identifier of each ONU and then auto-correlating the predetermined number of symbols with a subsequent segment, and wherein the predetermined number of symbols before the frame synchronization and ONU mark sequence start position is multiplied by an identifier of each ONU and then auto-correlating the predetermined number of symbols with a subsequent segment, and the formula used is:
wherein p represents the serial number of the ONU, and p is a positive integer, ONUid [p] Denotes the ONU identifier with serial number p, h denotes the frame synchronization and the ONU mark sequence start position, U (p) denotes the result of the autocorrelation of the first 128 symbols multiplied by the ONU identifier with serial number p, N denotes the number 128, r denotes the number x Denotes a received symbol of X polarization, k denotes k data from 0 to 2N-1 after m symbols, and m denotes an m-th symbol.
7. The preamble design method for an upstream burst mode in a coherent PON according to claim 4, wherein in the first part, a sign relation of X-polarization and Y-polarization satisfies:
TY[2n]＝±TX[2n]
TY[2n+1]＝±j×TX[2n+1]
wherein, TY takes value 1, j, -1 or j randomly, j is complex unit, n is code element serial number.
8. The method of preamble design for an upstream burst mode in a coherent PON of claim 7, wherein identifying the current ONU is performed while further comprising:
using the frame sync and the first part of the ONU mark sequence to perform a depolarization matrix [ a, B; -B, a ] by the formula:
r x ×(r y ) * ＝±(A 2 -B 2 ) When TY ± + -TX
r x ×(r y ) * ＝mj(A 2 -B 2 ) When TY is + -jTX
Wherein r is x Received symbols representing the X polarization, r y The received symbol representing the Y polarization, the conjugate symbol, a and B represent the parameters in the polarization matrix.
9. The method of claim 8, wherein after the de-polarization multiplexing, the frequency offset estimation, and the ONU identification are completed, the method further comprising:
extracting the self-adaptive filter coefficient calculated by the previous frame data from the register, and taking the extracted self-adaptive filter coefficient as an initial coefficient of the self-adaptive filter;
and adopting a CMA adaptive equalization algorithm, performing channel estimation by using a channel estimation sequence, and storing the coefficient of the current adaptive equalizer into a local corresponding register.
10. A preamble design system for an upstream burst mode in a coherent PON, comprising:
the system comprises a construction module, a channel estimation module and a clock recovery module, wherein the construction module is used for constructing a lead code structure, and the constructed lead code comprises a clock recovery sequence, a frame synchronization and ONU mark sequence and a channel estimation sequence;
the recovery module is used for performing clock recovery based on the clock recovery sequence when the OLT receives the DSP;
the calculation module is used for multiplying the symbol with the preset number at the front section by the synchronous sequence code based on the sliding window and then carrying out self-correlation on the result with the symbol with the preset number at the rear section to obtain a frame synchronization and an ONU mark sequence synchronization head;
and the identification module is used for identifying the current ONU based on the maximum value obtained by multiplying the number symbol set at the front section of the frame synchronization and the initial position of the ONU marker sequence by the identifier of each ONU and then performing autocorrelation on the same number symbol set at the rear section.
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| CN111371522A (en) * | 2018-12-25 | 2020-07-03 | 中兴通讯股份有限公司 | Burst clock synchronization method, burst frame transmission method, burst clock synchronization device, burst frame transmission device, equipment and storage medium |
| WO2020142726A1 (en) * | 2019-01-04 | 2020-07-09 | Futurewei Technologies, Inc. | Passive optical network (pon) synchronization and clock recovery |
| WO2020197013A1 (en) * | 2019-03-27 | 2020-10-01 | (주)자람테크놀로지 | Multi-level optical receiving device and method with improved burst mode clock and data recovery performance |
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| WO2020142726A1 (en) * | 2019-01-04 | 2020-07-09 | Futurewei Technologies, Inc. | Passive optical network (pon) synchronization and clock recovery |
| WO2020197013A1 (en) * | 2019-03-27 | 2020-10-01 | (주)자람테크놀로지 | Multi-level optical receiving device and method with improved burst mode clock and data recovery performance |
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