WO2013104184A1

WO2013104184A1 - Method, device and system for signal processing based on single carrier-frequency domain equalization(sc-fde)

Info

Publication number: WO2013104184A1
Application number: PCT/CN2012/079163
Authority: WO
Inventors: 高健; 易鸿
Original assignee: 中兴通讯股份有限公司
Priority date: 2012-01-09
Filing date: 2012-07-26
Publication date: 2013-07-18
Also published as: CN102447659B; CN102447659A

Abstract

A signal processing method based on single carrier-frequency domain equalization(SC-FDE), includes: an optical transmitter generating unique words(UW) sequence and a synchronous data block, providing a data frame with the unique words sequence, generating a superframe by the synchronous data block and the data frame, and transmitting the superframe as a base-band signal to an optical receiver. A signal processing system is based on SC-FDE. Said solution enable simplifying a process of an optical transmitter hardware device, reducing manufacturing cost of the optical transmitter, improving accuracy of time synchronization and reducing processing resources of channel estimation.

Description

Signal processing method, device and system based on single carrier frequency domain equalization

Technical field

The present invention relates to signal processing technologies in the field of optical fiber communication, and in particular, to a signal processing method, apparatus and system based on Single Carrier-Frequency Domain Equalization (SC-FDE). Background technique

In the signal transmission process of the optical fiber communication system, due to the dispersion and polarization mode dispersion (PMD) caused by high-rate transmission, the distortion and distortion of the transmission channel are caused, and the distortion and distortion of the transmission channel further cause the code. Inter-interference, inter-symbol interference is a major factor affecting the quality of communication in fiber-optic communication systems. Therefore, SC-FDE technology is used in fiber-optic communication systems to solve inter-symbol interference problems.

One method for solving the inter-symbol interference problem in the SC-FDE technology is a signal processing method for inserting a training sequence, which is specifically: The optical transmitter uses the training sequence as a unique word (UW, Unique Word) and the data to be transmitted (Data Forming a data frame, transmitting the modulated signal modulated by the data frame to the optical receiver; the optical receiver demodulating the received modulated signal to obtain the demodulated data frame, and then using the demodulated data frame The UW performs time synchronization, frequency offset estimation, and channel estimation.

The structure of the data frame is as shown in FIG. 1 , which is composed of two UWs and data before and after, and one UW is overlapped between each frame of data; the UW is a sequence of length M+2L, and the method for forming the UW is: First, a specific sequence of length M is generated, and the last L symbols in the specific sequence are copied, and a prefix is formed before being added to the sequence of length M, and the first L symbols in the specific sequence are copied and added to the sequence of length M. A suffix is formed to form a UW having a length of M+2L. The specific sequence of length M uses the constant envelope zero autocorrelation (CAZAC, Const Amplitude Zero Auto-Corelation) sequence as the optimal sequence. The time synchronization, the frequency offset estimation, and the channel estimation by using the UW in the demodulated data frame include: The current method for performing time synchronization is the Schmidl method, and the frequency offset estimation is based on time synchronization calculation, and the channel estimation is performed. In order to use the maximum likelihood estimation method. However, the above method of inserting the training sequence has the following problems:

1. The data frame composed of the CAZAC sequence needs to use a high-end digital-to-analog converter (DAC), and the high-end DAC has a complicated structure and high price;

Second, the Schmidl synchronization calculation method used by the above signal processing method for time synchronization, since the two UWs in the demodulated data frame are the same, there is a problem that the determined synchronization position is not accurate enough, and the Schmidl synchronization calculation method is related. The peak is not sharp enough;

3. The maximum likelihood estimation method used in the channel estimation of the above signal processing method requires a large number of matrices and inverse matrix operations, so the computational complexity is large, and thus the processing resources of the optical receiver are occupied.

It can be seen that the existing signal processing method for inserting the training sequence cannot simplify the optical transmitter hardware device and reduce the cost of the optical transmitter, and cannot guarantee the accuracy of the time synchronization, and the optical receiver is occupied by the channel estimation. Large processing resources.

Summary of the invention

In view of the above, an object of the present invention is to provide a SC-FDE-based signal processing method, apparatus, and system, which simplify the optical transmitter hardware device and reduce the cost of the optical transmitter, and improve the accuracy of time synchronization, and Reduce the processing resources used in channel estimation.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

The invention provides a signal processing method based on SC-FDE, the method comprises: generating a UW sequence and a synchronization data block by using an optical transmitter, forming a data frame by using a UW sequence, and forming a super frame by using the synchronization data block and the data frame, The super frame is sent to the optical receiver as a baseband signal.

The present invention provides a signal processing method based on SC-FDE, the method comprising: after receiving the baseband signal sent by the optical transmitter, the optical receiver performs sliding calculation on the received super frame by using the synchronous data block. Time synchronization, and then using the UW sequence for correlation calculation to obtain channel estimation values.

The present invention also provides an SC-FDE-based signal processing system, the system comprising: an optical transmitter and an optical receiver; The optical transmitter is configured to generate a UW sequence and a sync data block, use a UW sequence to form a data frame, use a sync block and a data frame to form a super frame, and send the super frame as a baseband signal to the optical receiver; the optical receiver It is set as follows: After receiving the baseband signal sent by the optical transmitter, the synchronized superblock is used for sliding calculation of the received superframe for time synchronization, and then the UW sequence is used for channel estimation.

The present invention provides an optical transmitter comprising: a transmission signal processing module and an optical modulation module;

The sending signal processing module is configured to: generate a UW sequence and a sync data block, use a UW sequence to form a data frame, use a sync data block and a data frame to form a super frame, and send the super frame to the optical modulation module; the optical modulation module is set to: receive and send The super frame sent by the signal processing module is used as a baseband signal, and the baseband signal is modulated and sent to the optical receiver.

The present invention also provides an optical receiver, the optical receiver comprising: a receiving signal processing module and an optical demodulation module;

The optical demodulation module is configured to: receive a modulated signal sent by the optical transmitter, demodulate the modulated signal to obtain a baseband signal, and send the demodulated baseband signal to the received signal processing module;

The receiving signal processing module is configured to: after receiving the baseband signal sent by the optical demodulation module, perform time synchronization on the received superframe by using the synchronization data block, and then perform channel estimation by using the UW sequence.

BRIEF abstract

1 is a schematic structural diagram of a data frame in the prior art;

2 is a schematic diagram of a signal processing flow of an optical transmitter in a signal processing method based on SC-FDE according to the present invention;

3 is a schematic structural diagram of a synchronization data block generated in an optical transmitter according to the present invention;

4 is a schematic structural diagram of a super frame in an optical transmitter according to the present invention;

5 is a schematic diagram of a signal processing flow of an optical receiver in a signal processing method based on SC-FDE according to the present invention;

FIG. 6 is a schematic diagram of the composition of a signal processing system based on SC-FDE according to the present invention. Preferred embodiment of the invention

The basic idea of the embodiment of the present invention is: an optical transmitter generates a UW sequence and a synchronization data block, uses a UW sequence to form a data frame, uses a synchronization data block and a data frame to form a super frame, and transmits the super frame as a baseband signal to the optical receiving signal. After receiving the baseband signal, the optical receiver performs time synchronization on the received superframe by using a synchronization data block, and then performs correlation calculation using the UW sequence to obtain a channel estimation value.

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The signal processing flow of the optical transmitter in the SC-FDE based signal processing method proposed by the present invention is as shown in FIG. 2, and includes the following steps:

Step 101: The optical transmitter generates a UW sequence and a sync block, and uses the UW sequence and the to-be-sent

Data consists of a data frame, which consists of a sync block and multiple data frames.

Here, the generating UW sequence is: Using a binary sequence to form a UW sequence, the binary sequence can be selected according to the following conditions:

M ....+. k = 0

M-1

u(ri)u({n + k) mod ): 4-M ....... k=M/2; where, is the UW sequence, M is

0 else

The length of the UW sequence, Λ = Ο, Ι, ..., -Ι; u(n)e{+\,-\], « = 0,1,..., -1; The length of the sequence is 4. Multiple

The M/ ² _l and M-1 in the set are set to -1; the first half of the sequence is complementary to the second half:

u{ri) = -u{n+MI2, n = Q,..., MI2-2. The binary sequence is an existing sequence in the prior art, and is not mentioned here; the method of selecting a binary sequence according to the above conditions is prior art, and is not mentioned here;

The synchronous data block is composed of: a three-segment synchronization sequence of eight, B, and C. As shown in FIG. 3, the A-segment synchronization sequence is L bits long, and the B and C synchronization sequences are each N bits; wherein, A The L bit data of the synchronization sequence is a binary sequence ⁵ (") (n=N/2-L, ..., N/2-l); the B and C synchronization sequences are Sync(n) , Sync(n) = s (n)x(n) . where, for a binary sequence of length N, the condition for selecting ^x (" the binary sequence is the same as when the UW sequence is generated:

N + .. k = 0

N-\

^ χ(ή)χ((η + k) mod N): 4-N ....... k = N/2; the length of N, k = 0,\,...,N-\

0 else x(n)e{+\,-\}, n = 0 ...,N-\; The length of the x(«) sequence is a multiple of 4; the N/2-1 and Nth in -1 is set to -1;

The first half of the sequence is complementary to the second half: x(i) = -x(i + NI }, n = Q,..., NI2-2. The ") can be based on conditions

Selected. The component data frame is: adding the same two UWs of length M to the front and rear ends of the Data to form a data frame; the composition super frame is: adding the synchronization data block before multiple data frames, such as As shown in FIG. 4, the super frame includes a sync block and a plurality of data frames, and each data frame includes two UWs and a segment of Data. The plurality of the multiple frames are determined according to the number of subframes included in the super frame specified in the prior art.

In addition, since the optical signal generating device generates two baseband signals of different polarization states in the prior art, in the same manner as in the step 101, another UW sequence and a sync data block of the polarization state are generated in the same manner. The UW sequence and the Data to be transmitted constitute a data frame, and a synchronization block and a plurality of data frames form a super frame;

The UW sequence of the other polarization state may be a d-cycle of one UW sequence of two polarization states; the synchronization data block of the other polarization state and one of the two polarization states are synchronized data blocks. the same.

Step 102: The optical transmitter modulates the baseband signal composed of the super frame to become a modulated signal, and transmits the modulated signal to the optical receiver.

Here, the modulation is prior art, and the specific modulation process is not mentioned here. The baseband signal can be modulated using a Mach-Zehnder modulator.

The signal processing flow of the optical receiver in the SC-FDE based signal processing method proposed by the present invention is as shown in the figure As shown in 5, the following steps are included:

Step 201: After receiving the modulated signal sent by the optical transmitter, the optical receiver demodulates the modulated signal to obtain a baseband signal.

Here, the demodulation is prior art, and the specific demodulation process is not mentioned here;

The demodulation to obtain a baseband signal can be expressed as:

L-1

∑ (A! (k)s, (n - k) + } ₂ (k)s ₂ (n - A: "

r(w) : ■■ w(n) + exp(j(Amr _s n)

L-1

r ₂ (n)

∑ (^2i ( ^k ) ^s i (n - k) + h ₂₂ (k)s ₂ (n - k)) where represents the baseband signal demodulated by the optical receiver; and respectively represents the optical receiver solution The two polarization states of the baseband signal are obtained; the carrier frequency deviation is the analog-to-digital converter (ADC, Analog-Digital-Convertor) sampling time interval frequency; ^w (") is Gaussian white noise; W is the impulse response function The expression, which is prior art, is not mentioned here; and represents the baseband signals of the two polarization states generated by the optical transmitter respectively. Step 202: The optical receiver performs sliding calculation on the demodulated baseband signal. Synchronize.

Here, the time synchronization for performing the sliding calculation on the received super frame includes: the optical receiver starts to read data of a length greater than 2N from any one of the demodulated baseband signals of the two polarization states as synchronization. Calculating a signal; performing a slip calculation on the synchronous calculation signal read by using the length N generated by itself; the demodulated baseband signal data corresponding to the maximum value in the result of the sliding calculation is a time synchronization position;

The time synchronization position is a frame header position of the demodulated baseband signal, that is, a frame header of the baseband signal can be found by determining a position of the time synchronization;

The maximum value in the result of the sliding calculation is: if the baseband signal whose length is greater than 2N is not calculated, the baseband having a length greater than 2N is read again from the baseband signal read this time. The signal is determined until the maximum value of the slip calculation result is obtained; wherein, the maximum value may be determined according to whether the result of the sliding calculation is greater than a preset threshold value, for example, the threshold value may be preset to be 0.9;

N represents the length of the B or C synchronization sequence in the isochronous data block; the binary sequence used to generate the isochronous data block for the optical transmitter, the same method used by the optical transmitter in the optical receiver to generate the sequence, The degree is the same as in the optical transmitter, which is N;

The slip calculation can include the following calculation steps:

P _x (m)^ ∑ ^(k)x(k + N 12)r _x (m + k)r^ (m + k + N/2) ,

k

P» ^ x(k)x(k + N/2)r ₂ (m + k)r^(m + k + N/2);

k

Ί ,

M _{Λ /Ί} (m) = \Ρ ¹ )\ + 1^ ² (^)1

R) ^) ; The time synchronization position is the data m with the largest value of ( ^∞ ), which can be expressed as: d = arg max(M(m)) Step 203: The optical receiver performs the synchronized baseband signal The frequency deviation estimation eliminates the frequency deviation based on the frequency deviation estimation result, and obtains the baseband signal after eliminating the frequency deviation.

Here, the frequency deviation estimation may be: using the length N generated in step 202 to perform correlation calculation on data having a length greater than 2N read from the frame header position of the synchronized baseband signal, and bring in different frequencies. Performing calculations, and obtaining the frequency offset value corresponding to the maximum value in the result is the finally obtained frequency deviation estimation value;

Wherein, the correlation calculation can use a formula:

r(N- k)r" (N + k)x(N - k)x(N + k) , .

Ti \r(Nk)r (N + k)\ . =- argmax{|0( )| ² }

The frequency offset value corresponding to the maximum value may be expressed as: 2 ^JJ ·, the eliminating the frequency deviation according to the frequency deviation estimation result is a prior art, and may include: using the calculated frequency deviation estimation value to the received synchronized The baseband signal is frequency-adjusted to obtain a frequency-adjusted baseband signal.

Further, if the user needs a more accurate frequency deviation estimation, the user may set a The baseband signal after the frequency deviation is subjected to the second frequency deviation estimation, and then the frequency deviation is eliminated according to the frequency deviation estimation result, and the baseband signal after the frequency deviation is eliminated is obtained.

Wherein, the second frequency deviation estimation uses a formula:

Bring in different frequencies for calculation, and then

N

f =― argmax{|0( )| }

The maximum value in the result is calculated using the formula 2 ⁵ / ^{11 to} calculate the second frequency deviation estimate.

Step 204: The optical receiver performs channel estimation on the baseband signal after eliminating the frequency offset ₍ here, the baseband signal after canceling the carrier frequency deviation may be expressed as:

1=0

w(ri) +

1=0 w = 0,l,... 1 The channel estimation includes: the optical receiver generates a UW sequence of length M according to the manner in which the optical transmitter generates the UW sequence, and utilizes the UW sequence generated by itself and eliminates The baseband signal after the carrier frequency deviation is correlated and the channel estimation result is obtained;

Wherein, the correlation calculation can use the following formula:

-1 -1 -1 L-1

^r _x (n + k)u (k) = ^w _l (n + k)u + (l)u _x (n + kl) +J ₂ (l)u ₂ (n + k- l)]u _x (k) , k 0 k Q k 0 0

^r _x (n + k)u (k) = ^w _l (n + k)u + (l)u _x (n + kl) +J ₂ (l)u ₂ (n + k- l)]u ₂ (k) k 0 k 0 k 0 0

r ₂ (n + k)u (k) = w ₂ (n + k)u (k) + [h _2l (l)u _x (n + kl) +// ₂₂ (l) ₂ (nk_ /) ]/* (k) k 0 k 0 k 0 0

r ₂ (n + k)u (k) = w ₂ (n + k)u (k) + ^ ^ [h _2l (l)u _} (n + kl) +// ₂₂ (l) ₂ (nk— /)] / * (k) k 0 k 0 k 0 0 where, the UW sequence generated by the optical receiver, the length is M; If the cyclic shift d of the UW sequence in one polarization state relative to the UW sequence in the other polarization state satisfies ≤ ^{t < M/2} _ (- D then:

^u^n + k- l)u _x two 0, w≠ /, w, /two 0, 1,..., - 1

Two

Z^O + H)^) 2 0,", / 2 0,1,..., - 1

^u ₂ (n + k- l)u _x (k) = 0, ^/two 0,1,..., -1

^u ₂ (n + k- l)u (k) = 0, w≠ /, / = 0, 1,..., - 1

Let h〗 = [ ... Α(Ζ_1), /3⁄4 ₂ (0),...,/3⁄4 ₂ (-1)] ^Γ ,

h ₂ =[/; ₂₁ (0),...,/; ₂₁ (Zl),/; ₂₂ (0X...,/; ₂₂ (Zl) ,

i + L- l)u ₂ (k)

Ύ2 (k + L- l)u ₂ (k)

w, = ∑ ^ (k * (k), ...^w^k + L- l)u _x (k Z w _x (k)u ₂ (k ...^w^k + L- l) u ₂ (k)

w _n = ∑ ^ ₂ (k)u _x (k\ ...^w^k + L- l)u _x (k\ Z w ₂ (k)u ₂ (k\ ...^w^k + L- l)u ₂ (k) is available: h, (y, -w,), h ₇ =—(y ₉ -w ₇ ) ;

¹ M ^{l 2} M ^2> where ^h i represents the channel impulse response function of the two polarization states, and y, y ₂ represents the results of the correlation calculation between the baseband signals of the two polarization states and the UW sequence, and _Wl and w ₂ represent two Noise in one polarization state;

When _Wl and ^ are zero in the above formula, the obtained ^ is corresponding to the two polarization states respectively. The channel estimate can be expressed as: = ^.

M,

As shown in FIG. 6, the present invention provides an SC-FDE-based signal processing system, which includes: an optical transmitter 21 and an optical receiver 22;

The optical transmitter 21 is configured to generate a UW sequence and a sync data block, use a UW sequence to form a data frame, use a sync block and a data frame to form a super frame, and send the super frame as a baseband signal to the optical receiver 22;

The optical receiver 22 is configured to receive the baseband signal sent by the optical transmitter 21, perform time synchronization on the received superframe by using a synchronization data block, and perform channel estimation by using the UW sequence.

The optical transmitter 21 is specifically configured to use a binary sequence to form a UW sequence, and the binary sequence can be selected according to the following conditions:

M . +. k = 0

-1

u(n)u((n + k) mod ): 4-M ....... k=M/2; where, is a UW sequence, M is 0 0 else

The length of the UW sequence, Λ = Ο, Ι, ..., -Ι; u(n)e{+\,-\], « = 0,1,..., -1;

The length of the sequence is a multiple of 4;

The M/ ² _l and M-1th in the setting are set to -1;

The first half of the sequence is complementary to the second half:

u{ri) = -u{n+MI2, n = Q,..., MI2-2.

The optical transmitter 21 is specifically configured to generate a binary sequence of L symbol lengths as an A-synchronous sequence when generating a sync data block, and generate a binary sequence of length N 3⁄4^ (synchronized as B and C) Sequence

Where = is a binary sequence of length N, and the conditions of the selected binary sequence are the same as those for generating the UW sequence: N +..... k = 0

W-1

x(ri)x({n + k) mod N) = 4-N ....... k = N/2; the length of N is, k = 0,\,...,N-\

0 else

x(n)e{+\,-\}, n = 0 ...,N-\;

The length of the x(«) sequence is a multiple of 4;

The N/2-1th and N-1th settings in the middle are set to -1;

The first half of the sequence is complementary to the second half: x(i) = -x( i + N 12,, n = Q, ..., Ν 12-2 can be based on conditions

Selected. The optical transmitter 21 is specifically configured to add the same two UWs of length M to the front and rear ends of the Data to form a data frame; and add the synchronization data block to form a super frame before the multiple data frames.

The optical transmitter 21 is specifically configured to generate two baseband signals of different polarization states according to the prior art, so that while generating one super frame, another UW sequence and synchronization data of another polarization state are generated in the same manner. Block, using a UW sequence and the data to be transmitted to form a data frame, using one sync block and a plurality of data frames to form a super frame; wherein the other polarization state UW sequence may be UW of the other of the two polarization states The cyclic shift of the sequence; the sync block of the other polarization state is identical to one of the two polarization states.

The optical transmitter 21 is further configured to use the super frame as a baseband signal, modulate the baseband signal, and send the signal to the optical receiver 22. Correspondingly, the optical receiver 22 is further configured to receive the optical transmitter. The modulated signal sent from 21 demodulates the modulated signal to obtain a baseband signal.

The optical receiver 22 is specifically configured to start reading data of a length greater than 2 任意 from any one of the baseband signals of the two polarization states obtained by demodulation as a synchronization calculation signal; Sliding calculation is performed on the synchronous calculation signal read above; the demodulated baseband signal data corresponding to the maximum value in the result of the sliding calculation is a time synchronization position; wherein Ν indicates a B or C synchronization sequence in the synchronization data block Length; for light transmitter 21 The binary sequence used in generating the sync data block is generated by the optical receiver 22 using the same method as the optical transmitter 21, and the length is the same as N in the optical transmitter 21;

The slip calculation can include the following calculation steps:

P _x (m)^ ∑ ^(k)x(k + N 12)r _x (m + k)r^ (m + k + N/2) ,

k

P» ^ x(k)x(k + N/2)r ₂ (m + k)r^(m + k + N/2);

k

R _x (m)^ ^ \r _x (m + k + N I2) R^m二^ \r (m + k + N 12)

k k ,

M _{Λ /ΊΊ} (m) = \Ρ ¹ )\ + 1^ ² (^)1

R) ^) ; The position of the time synchronization is the data m with the largest value of ( ^∞ ), which can be expressed as: d = arg max(M(m)) The optical receiver 22 is also used for synchronization. The baseband signal is subjected to frequency offset estimation, and the frequency deviation is eliminated according to the frequency deviation estimation result, and the baseband signal after the frequency deviation is eliminated is obtained.

The optical receiver 22 is specifically configured to perform correlation calculation on a data length of N greater than 2N from a frame header position of the synchronized baseband signal by using a length N generated by itself. Calculated by entering different frequencies, the frequency offset value corresponding to the maximum value in the result is the finally obtained frequency deviation estimation value;

Wherein, the correlation calculation can use a formula:

^ r(N- k)r" (N + k)x(N - k)x(N + k) , .

Ti \r(Nk)r (N + k)\ . =- argmax{|0( )| ² }

The frequency offset value corresponding to the maximum value can be expressed as: 2, ..., / represents the frequency deviation value.

Further, if the user needs a more accurate frequency deviation estimation, the second frequency deviation estimation is performed on the baseband signal after the frequency deviation is cancelled once, and then the frequency deviation estimation result is performed according to the frequency deviation. Eliminate the frequency deviation and obtain the baseband signal after eliminating the frequency deviation ₍

Wherein, the second frequency deviation estimation uses a formula:

Bring in different frequencies for calculation, and then

N

f =― argmax{|0( )| }

The maximum value in the result is calculated by using the formula 2 ⁵ / ^{11 to} calculate the second frequency deviation to estimate the optical receiver 22, specifically for performing channel estimation on the baseband signal after eliminating the carrier frequency deviation;

The baseband signal after canceling the carrier frequency deviation can be expressed as:

/))

w(ri) +

r ₂ (n)

Φ Φ ₂ (l)s, ("_/) + h ₂₂ (l)s ₂ (n - /))

w = 0, l, ... 1 The optical receiver 22 is specifically configured to generate a UW sequence of length M according to the manner in which the optical transmitter 21 generates the UW sequence, using the UW sequence generated by itself and canceling the carrier frequency. The baseband signal after the deviation is correlated and the channel estimation result is obtained;

Wherein, the correlation calculation can use the following formula:

^r _x (n + k)u (k) = ^w _l (n + k)u + (l)u _x (n + kl) +J ₂ (l)u ₂ (n + k- l)]u _x (k)

^r _x (n + k)u (k) = ^w _l (n + k)u + (l)u _x (n + kl) +J ₂ (l)u ₂ (n + k- l)]u ₂ (k) r ₂ (n + k)u (k) = w ₂ (n + k)u (k) + [h _2l (l)u _x (n + kl) +// ₂₂ (l) ₂ ( Nk_ /)]/* (k)

^ r ₂ (n + k)u (k) = w ₂ (n + k)u (k) + ^ ^ [h _2l (l)u _} (n + kl) +// ₂₂ (l) ₂ (nk — /)]/* (k)

Wherein, the UW sequence generated by the optical receiver 22 has a length of M;

If the UW sequence in one polarization state is relative to the UW sequence in the other polarization state Cyclic shift d HL≤d<M/2H

^u^n + k- l)u _x (A) two 0, w≠ /, w, /two 0, 1,..., - 1

Z^O + H)^) 2 0,", / 2 0,1,..., - 1

,

Let h〗 = [ ..., /^_ι), /3⁄4 ₂ (ο),...,/^-ι)] ^Γ ,

h ₂ i + L- l)u ₂ (k) y ₂ (k + L- l)u ₂ (k)

w, = ∑ ^ (k)u _x (k), ...^w^k + L- l)u _x (k Z w _x (k)u ₂ (k ...^w^k + L- l)u ₂ (k)

w _n = ∑ ^ ₂ (k)u _x (k\ ...^w^k + L- l)u _x (k\ Z w ₂ (k)u ₂ (k\ ...^w^k + L- l)u ₂ (k) where ^h i represents the channel impulse response function of the two polarization states, and y, y ₂ represent the results of the correlation calculation between the baseband signals of the two polarization states and the UW sequence, _Wl , w ₂ Representing noise in two polarization states; when _Wl and ^ are zero in the above formula, the obtained ^h i , which is the channel estimation corresponding to the two polarization states, can be expressed as: h ^{l =} ^"( ^y " ^Wl )

The channel corresponding to the two polarization states is estimated to be: 丄 ii ₂ = ^ y ₂ .

M, M, the optical transmitter 21 includes: a transmission signal processing module 211 and a light modulation module 212; The signal processing module 211 is configured to generate a UW sequence and a synchronization data block, use a UW sequence to form a data frame, and use the synchronization data block and the data frame to form a super frame, and send the super frame to the optical modulation module 212;

The optical modulation module 212 is configured to receive the super frame sent by the transmission signal processing module 211 as a baseband signal, modulate the baseband signal, and send the signal to the optical receiver 22

The transmit signal processing module 211 is specifically configured to use a binary sequence to form a UW sequence, and the binary sequence can be selected according to the following conditions:

1 = 0

-1

^ u(n)u((n + k) mod ) = .k=M/2; where is the UW sequence, M is 0

Else

The length of the UW sequence, Λ = Ο, Ι, ..., -Ι;

u(n)e{+\,-\], « = 0,1,..., -1;

The length of the sequence is a multiple of 4;

The M/ ² _l and M-1th in the setting are set to -1;

The first half of the sequence is complementary to the second half:

u{ri) = -u{n+MI2, n = Q,..., MI2-2. The transmission signal processing module 211 is specifically configured to generate a binary sequence ⁵ (") of L symbol lengths as an A synchronization sequence when generating a synchronization data block, and generate a binary sequence of length N as a B and C synchronization sequence. ;

Where = is a binary sequence of length N, and the conditions of the selected binary sequence are the same as those for generating the UW sequence:

N + .. k = 0

N-\

^ χ(ή)χ((η + k) mod N) = 4-N ....... k = N/2; the length of N, k = 0,\,...,N-\ 0 0 else

x(n)e{+\,-\}, n = 0 ...,N-\;

The length of the x(«) sequence is a multiple of 4; The N/2-1 and Nl in the setting are set to -1;

The first half of the sequence is complementary to the second half: x( i) =—x( i + N 12,, n = Q, ..., Ν 12-2 can be based on conditions

Selected. The sending signal processing module 211 is specifically configured to add the same two UWs of length M to the front and rear ends of the Data to form a data frame; and add the synchronization data block to form a super frame before the plurality of data frames.

The transmit signal processing module 211 is specifically configured to generate baseband signals of two different polarization states according to the prior art, so that while generating one super frame, the UW sequence and synchronization of another polarization state are generated in the same manner. a data block, comprising a UW sequence and a data to be transmitted to form a data frame, and a synchronization data block and a plurality of data frames to form a super frame; wherein the another polarization state UW sequence may be the other of the two polarization states D-cycle shift of the UW sequence.

The optical receiver 22 includes: a receiving signal processing module 221 and an optical demodulation module 222;

The optical demodulation module 222 is configured to receive the modulated signal sent by the optical transmitter 21, demodulate the modulated signal to obtain a baseband signal, and send the demodulated baseband signal to the received signal processing module 221;

The receiving signal processing module 221 is configured to receive the baseband signal sent by the optical demodulation module 222, perform time synchronization on the received superframe by using a synchronization data block, and perform channel estimation by using the UW sequence.

The receiving signal processing module 221 is specifically configured to start reading data of a length greater than 2Ν from any one of the two baseband signals obtained by demodulation as a synchronous calculation signal; Performing a slip calculation on the synchronous calculation signal read above; the demodulated baseband signal data corresponding to the maximum value in the result of the sliding calculation is a time synchronization position;

Where Ν denotes the length of the B or C synchronization sequence in the isochronous data block; for the optical transmitter 21 The binary sequence used to generate the isochronous data block is generated by the optical receiver 22 in the same manner as the optical transmitter 21, and the length is the same as that in the optical transmitter 21.

The received signal processing module 221 is further configured to perform frequency offset estimation on the synchronized baseband signal, eliminate frequency offset based on the frequency offset estimation result, and obtain a baseband signal after eliminating the frequency offset.

The receiving signal processing module 221 is specifically configured to perform correlation calculation by using data of a length N greater than 2N read from a frame header position of the synchronized baseband signal by using a length N generated by itself. The frequency is calculated by different frequencies, and the frequency offset corresponding to the maximum value in the result is the finally obtained frequency deviation estimation value;

Further, if the user needs more accurate frequency deviation estimation, the second frequency deviation estimation may be performed on the baseband signal after the frequency deviation is eliminated, and the frequency deviation is eliminated according to the frequency deviation estimation result, and the frequency deviation is obtained after the frequency deviation is obtained. Baseband signal;

Wherein the second frequency deviation estimate is used in the formula:

Φ( )

Bring different frequencies into the calculation, and then get the knot = argmax{| 0( ) | ² }

The maximum value in the fruit is calculated using the formula 2 ⁵ / ^{11 to} calculate the second frequency deviation estimate. The receiving signal processing module 221 is specifically configured to perform channel estimation on the baseband signal after eliminating the carrier frequency deviation after eliminating the carrier frequency deviation according to the result of the frequency offset estimation.

The receiving signal processing module 221 is specifically configured to generate a UW sequence of length M according to the manner in which the optical transmitter 21 generates the UW sequence, and use the UW sequence generated by itself to perform correlation calculation with the baseband signal after eliminating the carrier frequency deviation. Channel estimation result.

The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Industrial Applicability The SC-FDE-based signal processing method, device and system provided by the embodiments of the present invention have The following advantages and features are available: The UW sequence generated by the optical transmitter uses a binary sequence. Since the binary sequence is simpler than the CAZAC sequence, it is not necessary to use a high-end and complex DAC in the optical transmitter, thereby simplifying optical signaling. Machine hardware equipment and reduce the cost of optical transmitters.

In addition, the embodiment of the present invention performs time synchronization on the received superframe by using the synchronization data block generated by itself in the optical receiver, since the synchronization data block has only one in one super frame, thus, compared with the existing method. It is more accurate to synchronize with two identical UW sequences per data frame; and the use of sliding calculation can avoid the problem that Schmidl synchronous calculation of the correlation peak is not sharp enough, and the sliding calculation is more accurate than the Schmidl synchronization calculation;

In the optical receiver of the embodiment of the invention, the correlation calculation is used to obtain the channel estimation value, and the correlation calculation can be compared with the maximum likelihood estimation method used in the existing method, and the correlation calculation does not need to perform the inverse matrix operation, and has a small amount of calculation and occupation. The advantage of less resources.

Claims

Claim

A signal processing method based on single carrier frequency domain equalization SC-FDE, the method comprising: the optical transmitter generates a unique word UW sequence and a synchronization data block, and the UW sequence is used to form a data frame, and the synchronization data block and the data frame are used. The super frame is formed, and the super frame is sent as a baseband signal to the optical receiver.

2. The method according to claim 1, wherein the generating the UW sequence comprises: forming a UW sequence using the binary sequence, and selecting the binary sequence according to the following conditions:

M ....+. k = 0

-1

^ u(n)u((n + k) mod ) = 4-M ....... k=M/2; where is the UW sequence, M is 0

0 else

Length of the UW sequence, 4 = 0,1,..., M-1; u(n)e{+\,-\], « = 0,1,..., -1; length of the sequence Is a multiple of 4;

The M/ ² _l and M-1th in the setting are set to -1;

The first half of the UW sequence is complementary to the second half:

u{ri) = -u{n+MI2, n = Q,..., MI2-2.

3. The method according to claim 1, wherein the synchronous data block is:

It consists of three-segment BC three-sequence synchronization sequence. The A-segment synchronization sequence is L bits long, and the B and C synchronization sequences are each N bits long. The L-bit data of the A-synchronization sequence is a binary sequence (n=N/2). -L, N/2-1); The synchronization sequence of B and C is " ^c ( , Sync(n) = s (η)χ( ) ^ is a binary sequence of length Ν, the condition of the selected binary sequence and The conditions for selecting a binary sequence are the same when generating a UW sequence;

[s(n) = s(n + N 12) « = 0,1,..., N/2-1 where ") can be based on the condition (") ⁼ s(W_") « = 1, 2,..., N/2-1 selected.

4. The method according to claim 1, wherein, after the superframe is sent as a baseband signal to the optical receiver, the method further comprises: the optical receiver receiving the baseband signal sent by the optical transmitter Then, using the synchronous data block to perform sliding calculation on the received super frame for sliding calculation, and then performing correlation calculation using the UW sequence to obtain the channel estimation value.

5. The method according to claim 4, wherein the performing time synchronization on the received superframe by using the synchronization data block comprises:

The optical receiver separately reads the two baseband signals of the two polarization states, and the length of the baseband signals is greater than that of the synchronous data block.

Data of the sum of the lengths of the C synchronization sequences;

Performing a sliding calculation on the read partial baseband signal data by using a sequence generated by itself that is the same length as the length of the B or C synchronization sequence in the isochronous data block and the binary sequence used by the optical transmitter to generate the isochronous data block;

The demodulated baseband signal data corresponding to the maximum value in the result of the slip calculation is the time synchronization position.

The method according to claim 4, wherein before the obtaining the channel estimation value by using the UW sequence, the method further comprises: performing, by the optical receiver, frequency offset estimation on the time-synchronized baseband signal; The result of the deviation estimation eliminates the carrier frequency deviation and performs channel estimation on the baseband signal after eliminating the carrier frequency deviation.

7. The method according to claim 6, wherein the performing channel estimation on the baseband signal after canceling the carrier frequency deviation comprises: the optical receiver generating the UW of length M according to the manner in which the optical transmitter generates the UW sequence. The sequence uses the UW sequence generated by itself to perform correlation calculation with the baseband signal after eliminating the carrier frequency deviation, and obtains the channel estimation result.

8. A signal processing method based on SC-FDE, the method comprising:

After receiving the baseband signal from the optical transmitter, the optical receiver performs time synchronization on the received superframe by using the synchronization data block, and then uses the UW sequence to perform correlation calculation to obtain the channel estimation value.

9. The method according to claim 8, wherein before the optical receiver receives the baseband signal sent by the optical transmitter, the method further comprises: the optical transmitter generating the UW sequence and the synchronization data block, The UW sequence is used to form a data frame, the sync block and the data frame are used to form a super frame, and the super frame is sent as a baseband signal to the optical receiver.

10. The method according to claim 9, wherein the generating the UW sequence comprises: forming a UW sequence using a binary sequence, and selecting the binary sequence according to the following conditions:

M ....+. k = 0

-1

^ u(n)u((n + k) mod ) = 4-M ....... k=M/2; where is the UW sequence, M is 0

0 else

The M/ ² _l and M-1th in the setting are set to -1;

The first half of the UW sequence is complementary to the second half:

u{ri) = -u{n+MI2, n = Q,..., MI2-2.

11. The method according to claim 9, wherein the synchronous data block is:

It consists of a three-segment synchronization sequence of B C. The A-sequence synchronization sequence is L bits long, and the B and C synchronization sequences are each N bits long. The L-bit data of the A-synchronization sequence is a binary sequence.

(n=N/2-L,...,N/2-l ); The B and C synchronization sequence is " ^c ( , ync(n) = s(n)x(n) ^ is the length N The sequence of the binary sequence, the condition for selecting the binary sequence is the same as the condition for selecting the binary sequence when generating the UW sequence;

[s(n) = s(n + N 12) « = 0,1,..., N/2-1 where ") can be based on the condition (") = s(W_") « = 1, 2,..., N/2-1 selected.

The method according to claim 8, wherein the synchronizing the received superframe by using the synchronization data block to perform time synchronization includes:

The optical receiver respectively reads data of a length of the baseband signals of the two polarization states greater than a sum of lengths of the B and C synchronization sequences in the synchronization data block;

Using the length generated by itself to transmit the length of the B or C synchronization sequence in the isochronous data block The sequence of the same binary sequence used in generating the synchronous data block performs sliding calculation on the read partial baseband signal data;

13. The method according to claim 8, wherein, before the obtaining the channel estimation value by using the UW sequence for correlation calculation, the method further comprises: performing, by the optical receiver, frequency offset estimation on the time-synchronized baseband signal; The result of the deviation estimation eliminates the carrier frequency deviation and performs channel estimation on the baseband signal after eliminating the carrier frequency deviation.

The method according to claim 8, wherein the performing channel estimation on the baseband signal after canceling the carrier frequency deviation comprises: the optical receiver generating the UW of length M according to the manner in which the optical transmitter generates the UW sequence. The sequence uses the UW sequence generated by itself to perform correlation calculation with the baseband signal after eliminating the carrier frequency deviation, and obtains the channel estimation result.

15. A signal processing system based on SC-FDE, the system comprising: an optical transmitter and an optical receiver; wherein

The optical transmitter is configured to generate a UW sequence and a sync data block, use a UW sequence to form a data frame, use a sync block and a data frame to form a super frame, and send the super frame as a baseband signal to the optical receiver; the optical receiver It is set as follows: After receiving the baseband signal sent by the optical transmitter, the synchronized superblock is used for sliding calculation of the received superframe for time synchronization, and then the UW sequence is used for channel estimation.

16. An optical transmitter, the optical transmitter comprising: a signal processing module and a light modulation module; wherein

17. The optical transmitter according to claim 16, wherein The transmit signal processing module is configured to: form a UW sequence using a binary sequence, and select a binary sequence according to the following conditions:

M ....+. k = 0

-1

^ u(n)u((n + k) mod ) = 4-M ....... k=M/2; where is the UW sequence, M is two 0

0 else

The M/ ² _l and M-1th in the setting are set to -1;

The first half of the UW sequence is complementary to the second half:

u{ri) = -u{n+MI2, n = Q,..., MI2-2.

18. The optical transmitter according to claim 16, wherein

The sending signal processing module is configured to: consist of eight, B, and C three-sequence synchronization sequences, the A-segment synchronization sequence is L bits long, and the B and C synchronization sequences are each N bits long; wherein, the L-bits of the A-synchronization sequence The data is a binary sequence of ⁵ (") (11=^2,...^/2-1); the B and C synchronization sequences are

Sync(n) = s(n)x(n) , χ(η) is a binary sequence of length _Ν , and the condition of the selected binary sequence is the same as the condition for selecting the binary sequence when generating the UW sequence;

19. An optical receiver, the optical receiver comprising: a receiving signal processing module and an optical demodulation module; wherein

20. The optical receiver according to claim 19, wherein

The receiving signal processing module is configured to: respectively read data of a length of the baseband signals of the two polarization states greater than a sum of lengths of the B and C synchronization sequences in the synchronization data block; use the length generated by itself as the synchronization data block B or The sequence of the same sequence as the binary sequence used by the optical transmitter to generate the isochronous data block is subjected to a sliding calculation of the read partial baseband signal data; the maximum value in the result of the sliding calculation corresponds to the demodulation The baseband signal data is the position of time synchronization.

21. The optical receiver according to claim 20, wherein

The receiving signal processing module is configured to: perform frequency offset estimation on the time-synchronized baseband signal; cancel carrier frequency deviation according to the result of the frequency offset estimation, and perform channel estimation on the baseband signal after canceling the carrier frequency deviation.

22. The optical receiver according to claim 21, wherein

The receiving signal processing module is configured to: generate a UW sequence of length M according to a manner in which the optical transmitter generates a UW sequence, and perform a correlation calculation by using a UW sequence generated by itself and a baseband signal that cancels a carrier frequency deviation to obtain a channel estimation result. .