CN104901906A - Coherent optical communication channel estimation method and system - Google Patents

Abstract

The invention discloses a coherent optical communication channel estimation method. The method comprises the following steps: once a receiving end receives a frame of data, estimating the channel transfer function of a current frame according to a training sequence included in the current frame, using the estimated channel transfer function as initial estimation of the channel transfer function of the current frame, and saving the estimated channel transfer function; and reading the final estimation of the channel transfer function of a preview frame of the current frame, performing weighted average on the final estimation of the channel transfer function of the preview frame of the current frame and the initial estimation of the channel transfer function of the current frame if the final estimation of the channel transfer function of the preview frame is read, using the channel transfer function subjected to weighted average as the final estimation of the channel transfer function of the current frame, and saving the channel transfer function subjected to weighted average. Through adoption of the coherent optical communication channel estimation method, the transmission performance of a coherent optical communication system can be enhanced effectively under the situation of the same spectrum efficiency, or the training sequence overhead is reduced and the system efficiency is increased under the situation of certain system transmission performance requirement. The invention also discloses a coherent optical communication channel estimation system.

Description

A kind of coherent optical communication channel estimation methods and system

Technical field

The present invention relates to technical field of optical fiber communication, in particular a kind of coherent optical communication channel estimation methods and system.

Background technology

Along with the continuous progress of science and technology and the flourish of Internet industry, people are also more and more higher for the demand of communication quality and speed.Message volume to increase with exceeding the speed explosion type of Moore's Law, and form of service and demand are tending towards diversification, as cloud computing, high definition stream media, video conference etc.This communication system of giving the present age global undoubtedly and network bring larger challenge.Optical fiber communication, as the revolutionary character in modern communication networks and supportive technology, has not only become the most important thing in the research of the communications field, and becomes commercialization in communications industry, market-oriented focus and focus.

High speed optical fiber communication is using spectral efficient and anti-channel impairments ability as guarantee.Due to the fast development of Digital Signal Processing (DSP) technology, coherent optical communication technology accounts for obtain leading position gradually in various alternative solution, is able to extensive concern and research in optical fiber communication and network field.Coherent optical detection can extract the full detail of Received signal strength except intensity, and has better frequency selectivity and receiving sensitivity, and its receiving sensitivity is than direct-detection system height about 10 ~ 20dB.

As shown in Figure 1, coherent optical communication system is made up of radiating portion, fiber channel and receiving unit, wherein radiating portion comprises electric transmitter and RTO(Radio frequency-to-optical, radio frequency is to light) upconverter, receiving unit comprises OTR(Optical-to-radio frequency-to, and light is to radio frequency) low-converter and electric receiver.

At transmitter terminal, the electric transmitter of two covers produces the bit stream of two polarization directions (X polarization direction and Y polarization direction) respectively, then the baseband inphase road (I) and positive cross-channel (Q) signal that carry training sequence is produced by the Digital Signal Processing such as constellation mapping (DSP), I road signal and Q road signal export after digital to analog converter (DAC) conversion, the signal of telecommunication of two polarization directions carries out up-conversion by respective upconverter (light I/Q modulator), carry out conjunction by polarization beam combiner again to restraint, close the polarisation-multiplexed signal after bundle and send into fibre channel transmission.

At receiver end, the polarisation-multiplexed signal received is through optical filter filtering, filtered polarisation-multiplexed signal and local oscillator light carry out mixing by dual-polarization frequency mixer, signal after mixing carries out down-conversion by photoelectric detector, obtain I road and the Q roadbed charged signal of two polarization directions (X polarization direction and Y polarization direction), send into the analog to digital converter ADC of electric receiver, obtain digital signal and carry out Digital Signal Processing by electric receiver, after process, recover the bit stream of two polarization directions.

At the receiver end of coherent optical communication system, Digital Signal Processing mainly comprises: the compensation of receiver front end nonideal characteristic, Nonlinear Transformation in Frequency Offset Estimation and compensation, channel estimation and equalization, carrier phase recovery etc.Wherein, channel estimation and equalization is a very important part, and effect the impact that the amplitude of signal and phase place cause is eliminated or part elimination, channel so that carrier phase recovery subsequently and judgement to.Current coherent optical communication channel estimation and equalization method be mainly divided into based on the blind equalization of constant modulus algorithm and based on data-aided non-blind estimate with balanced.Compare blind equalization, a part of expense is introduced with balanced passing through based on data-aided non-blind estimate, also be, transmitting terminal periodically inserts the known sequence of receiving terminal (also known as training sequence) in time-domain data blocks, receiving terminal utilizes this training sequence to obtain channel transfer functions, carry out time domain or frequency domain equalization to the data received again, implementation method is comparatively simple.

As shown in Figure 2, existing is generally periodically add training sequence in transmitting terminal data block based on data-aided coherent optical communication channel estimation technique, each frame comprises one section of training sequence (training sequence is generally positioned at frame head), every section of training sequence is for the channel information of the data block after estimating this section of training sequence, before next section of training sequence, in order to obtain channel information accurately, every section of training sequence needs to comprise multiple training sequence and does the average of channel information, add overhead, reduce the spectrum efficiency of system.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of coherent optical communication channel estimation methods and system, effectively can improve the transmission performance of coherent optical communication system when spectrum efficiency is identical, or reduce training sequence expense, raising system effectiveness when system transfers performance requirement is certain.

In order to solve the problems of the technologies described above, the invention provides a kind of coherent optical communication channel estimation methods, the method comprises:

Receiving terminal often receives frame data, the training sequence comprised according to present frame estimates the channel transfer functions of present frame, the channel transfer functions estimated is preserved as the initial estimation of the channel transfer functions of present frame;

Read the final estimation of the channel transfer functions of the former frame of present frame, as read, then the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, the channel transfer functions after weighted average is preserved as the final estimation of the channel transfer functions of present frame.

Further, the method also comprises following feature:

The initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprises:

The final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\α}}_i){\hat{H}}_{i-1}\left(k\right)+{\mathrm{\α}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

Further, the method also comprises following feature:

The initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprises:

According to m frequency of the final estimation of the channel transfer functions of the former frame of current i-th frame phase value, and m frequency of the initial estimation of the channel transfer functions of current i-th frame phase value, estimate the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ik (), obtains θ _ithe estimated value of (k) n is the sum of frequency;

According to the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ithe estimated value of (k) phase rotating is carried out in the final estimation of the channel transfer functions of the former frame of current i-th frame, makes the phase place of the corresponding frequency of the initial estimation of the channel transfer functions of current i-th frame of phase alignment of each frequency of the channel transfer functions of the former frame of postrotational current i-th frame;

The initial estimation of the final estimation of the channel transfer functions of the former frame of current i-th frame through phase alignment and the channel transfer functions of current i-th frame is weighted on average, obtains the final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)e^{j{\widehat{\mathrm{\&theta;}}}_i\left(k\right)}+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

Further, the method also comprises following feature:

Also comprise: the weight coefficient α that the initial estimation of the channel transfer functions of current i-th frame is set according to following rule _i: accelerate the speed of following the trail of channel variation as needed, then increase the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i; As needs improve antimierophonic performance, then reduce the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i.

Further, the method also comprises following feature:

Also comprise: the final estimation of reading the channel transfer functions of the former frame of present frame, as do not read, then using the final estimation of the initial estimation of the channel transfer functions of described present frame as the channel transfer functions of described present frame.

In order to solve the problems of the technologies described above, present invention also offers a kind of coherent optical communication channel estimation system, this system comprises:

Initial estimation and preserve module, often receive frame data for receiving terminal, the training sequence comprised according to present frame estimates the channel transfer functions of present frame, the channel transfer functions estimated is preserved as the initial estimation of the channel transfer functions of present frame;

Final estimation and preservation module, for reading the final estimation of the channel transfer functions of the former frame of present frame, as read, then the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, the channel transfer functions after weighted average is preserved as the final estimation of the channel transfer functions of present frame.

Further, this system also comprises following feature:

Final estimation and preservation module, initial estimation for the final estimation of the channel transfer functions of the former frame by described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprising:

The final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

Further, this system also comprises following feature:

Final estimation and preservation module, initial estimation for the final estimation of the channel transfer functions of the former frame by described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprising:

According to m frequency of the final estimation of the channel transfer functions of the former frame of current i-th frame phase value, and m frequency of the initial estimation of the channel transfer functions of current i-th frame phase value, estimate the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ik (), obtains θ _ithe estimated value of (k) n is the sum of frequency;

According to the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ithe estimated value of (k) phase rotating is carried out in the final estimation of the channel transfer functions of the former frame of current i-th frame, makes the phase place of the corresponding frequency of the initial estimation of the channel transfer functions of current i-th frame of phase alignment of each frequency of the channel transfer functions of the former frame of postrotational current i-th frame;

The initial estimation of the final estimation of the channel transfer functions of the former frame of current i-th frame through phase alignment and the channel transfer functions of current i-th frame is weighted on average, obtains the final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)e^{j{\widehat{\mathrm{\&theta;}}}_i\left(k\right)}+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

Further, this system also comprises following feature:

This system also comprises:

Module is set, for arranging the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame according to following rule _i: accelerate the speed of following the trail of channel variation as needed, then increase the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i; As needs improve antimierophonic performance, then reduce the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i.

Further, this system also comprises following feature:

Final estimation and preservation module, for reading the final estimation of the channel transfer functions of the former frame of present frame, as do not read, then using the final estimation of the initial estimation of the channel transfer functions of described present frame as the channel transfer functions of described present frame.

Compared with prior art, a kind of coherent optical communication channel estimation methods provided by the invention and system, the correlation of interframe channel before and after utilizing, on the method basis of existing channel estimating, by the average weighted digital channel process of interframe, effectively can improve the transmission performance of coherent optical communication system when spectrum efficiency is identical, or reduce training sequence expense, raising system effectiveness when system transfers performance requirement is certain.

Accompanying drawing explanation

Fig. 1 is the structural representation of coherent optical communication system of the prior art.

Fig. 2 is the schematic diagram estimating channel based on training sequence of the prior art.

Fig. 3 is the flow chart of a kind of coherent optical communication channel estimation methods of the embodiment of the present invention.

Fig. 4 is the schematic diagram estimating channel based on training sequence of the embodiment of the present invention.

Fig. 5 is the structural representation of a kind of coherent optical communication channel estimation system of the embodiment of the present invention.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly understand, hereinafter will be described in detail to embodiments of the invention by reference to the accompanying drawings.It should be noted that, when not conflicting, the embodiment in the application and the feature in embodiment can combination in any mutually.

As shown in Figure 3, embodiments provide a kind of coherent optical communication channel estimation methods, the method comprises:

S10, receiving terminal often receives frame data, the training sequence comprised according to present frame estimates the channel transfer functions of present frame, the channel transfer functions estimated is preserved as the initial estimation of the channel transfer functions of present frame;

S20, read the final estimation of the channel transfer functions of the former frame of present frame, as read, then the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, the channel transfer functions after weighted average is preserved as the final estimation of the channel transfer functions of present frame.

The method can also comprise following feature:

Wherein, according to the channel transfer functions of the training sequence estimation present frame that present frame comprises, comprising: according to the channel transfer functions of the training sequence employing Least Square Method present frame that present frame comprises.Wherein, estimate that the method for channel transfer functions is except adopting least square method, can also adopt other methods of estimation of the prior art.

In existing conventional method, in coherent optical communication digital receiver, the training sequence through ADC sampling can be expressed as following formula (1) after discrete Fourier transform (DFT) transforms to frequency domain:

Y _i(k)=H _i(k)X _i(k)+N _i(k)； （1）

Wherein i represents the i-th frame, and k represents a kth frequency, k=1,2 ..., N _dFT; Y _ik () represents the i-th frame received, H _ik () represents the transfer function of the i-th frame, X _ik () represents the i-th frame sent, N _ik () represents the interchannel noise of the i-th frame.

According to criterion of least squares, channel estimating is carried out to the i-th frame, the channel transfer functions of the i-th frame estimated shown in (2):

${\tilde{H}}_i=\frac{Y_i\left(k\right)}{X_i\left(k\right)},k=\mathrm{1,2},...,N_{\mathrm{DFT}}---\left(2\right)$

Wherein, N _dFTbe the sum of frequency, also, receiving terminal carries out counting of above-mentioned DFT computing.

Preferably, read the final estimation of the channel transfer functions of the former frame of present frame, as do not read (such as, present frame is the first frame received), then using the final estimation of the initial estimation of the channel transfer functions of described present frame as the channel transfer functions of described present frame.

Preferably, as shown in Figure 4, the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprises:

The final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right)---\left(3\right)$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency, k=1, and 2 ..., N _dFT; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1,1-α _ifor the weight of the final estimation of the channel transfer functions of the former frame of current i-th frame; I>=2;

Wherein, the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _iarrange according to following rule: accelerate the speed of following the trail of channel variation as needed, then increase the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i; As needs improve antimierophonic performance, then reduce the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i;

Preferably, the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _ivalue as shown in the formula shown in (4):

$\left\{\begin{array}{cc}{\mathrm{\&alpha;}}_i=1/i,& i\&le;t\\ {\mathrm{\&alpha;}}_i=1/t,& i>t\end{array}\right.---\left(4\right)$

Also namely, the frame number as current i-th frame is less than or equal to threshold value t, t>1, then the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _ifor 1/i, the frame number as current i-th frame is greater than threshold value t, then the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _ifor 1/t;

Preferably, consider that the carrier wave start-phase of receiving terminal reception consecutive frame is different with clock synchronous point, therefore, the former frame of current i-th frame and the channel transfer functions of current i-th frame have phase difference θ _i(k); Ideally, θ _ik () is the linear function of frequency k, therefore, least square method can be adopted phase difference θ _ik () is estimated;

Therefore, in order to improve the accuracy of estimation further, the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprising:

According to m frequency of the final estimation of the channel transfer functions of the former frame of current i-th frame phase value, and m frequency of the initial estimation of the channel transfer functions of current i-th frame phase value, estimate the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ik (), obtains θ _ithe estimated value of (k) n _dFTit is the sum of frequency;

According to the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ithe estimated value of (k) phase rotating is carried out in the final estimation of the channel transfer functions of the former frame of current i-th frame, makes the phase place of the corresponding frequency of the initial estimation of the channel transfer functions of current i-th frame of phase alignment of each frequency of the channel transfer functions of the former frame of postrotational current i-th frame;

The initial estimation of the final estimation of the channel transfer functions of the former frame of current i-th frame through phase alignment and the channel transfer functions of current i-th frame is weighted on average, obtains the final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)e^{j{\widehat{\mathrm{\&theta;}}}_i\left(k\right)}+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right)---\left(5\right)$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency, k=1, and 2 ..., N _dFT; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1,1-α _ifor the weight of the final estimation of the channel transfer functions of the former frame of current i-th frame; I>=2.

Wherein, coherent optical communication system can be: coherent light OFDM(Orthogonal Frequency Division Multiplexing, orthogonal frequency division multiplexi) system, coherent light single carrier frequency domain equalization (CO-SCFDE) system or coherent light single carrier frequency division multiplexing (CO-SCFDM) system etc.

In each frame data, the way of multiple training sequence is inserted relative to transmitting terminal in prior art, after adopting method of the present invention, when transmitting terminal inserts training sequence in each frame, the number of training sequence can be reduced, and receiving terminal still can be protected to the accuracy of channel estimating.Therefore, the present invention effectively can reduce training sequence expense, improve system effectiveness when system transfers performance requirement is certain.

As shown in Figure 5, embodiments provide a kind of coherent optical communication channel estimation system, this system comprises:

Initial estimation and preserve module, often receive frame data for receiving terminal, the training sequence comprised according to present frame estimates the channel transfer functions of present frame, the channel transfer functions estimated is preserved as the initial estimation of the channel transfer functions of present frame;

Final estimation and preservation module, for reading the final estimation of the channel transfer functions of the former frame of present frame, as read, then the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, the channel transfer functions after weighted average is preserved as the final estimation of the channel transfer functions of present frame.

This system also can comprise following feature:

Preferably, final estimation and preservation module, initial estimation for the final estimation of the channel transfer functions of the former frame by described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprising:

The final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

Preferably, consider that the carrier wave start-phase of receiving terminal reception consecutive frame is different with clock synchronous point, therefore, the former frame of current i-th frame and the channel transfer functions of current i-th frame have phase difference θ _i(k); Ideally, θ _ik () is the linear function of frequency k, therefore, least square method can be adopted phase difference θ _ik () is estimated;

Therefore, in order to improve the accuracy of estimation further, final estimation and preservation module, initial estimation for the final estimation of the channel transfer functions of the former frame by described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprising:

According to m frequency of the final estimation of the channel transfer functions of the former frame of current i-th frame phase value, and m frequency of the initial estimation of the channel transfer functions of current i-th frame phase value, estimate the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ik (), obtains θ _ithe estimated value of (k) n is the sum of frequency;

According to the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ithe estimated value of (k) phase rotating is carried out in the final estimation of the channel transfer functions of the former frame of current i-th frame, makes the phase place of the corresponding frequency of the initial estimation of the channel transfer functions of current i-th frame of phase alignment of each frequency of the channel transfer functions of the former frame of postrotational current i-th frame;

The initial estimation of the final estimation of the channel transfer functions of the former frame of current i-th frame through phase alignment and the channel transfer functions of current i-th frame is weighted on average, obtains the final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)e^{j{\widehat{\mathrm{\&theta;}}}_i\left(k\right)}+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

Preferably, described system also comprises and arranges module:

Described module is set, for arranging the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame according to following rule _i: accelerate the speed of following the trail of channel variation as needed, then increase the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i; As needs improve antimierophonic performance, then reduce the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i.

Preferably, final estimation and preservation module, for reading the final estimation of the channel transfer functions of the former frame of present frame, as do not read, then using the final estimation of the initial estimation of the channel transfer functions of described present frame as the channel transfer functions of described present frame.

A kind of coherent optical communication channel estimation methods that above-described embodiment provides and system, the correlation of interframe channel before and after utilizing, on the method basis of existing channel estimating, by the average weighted digital channel process of interframe, effectively can improve the transmission performance of coherent optical communication system when spectrum efficiency is identical, or reduce training sequence expense, raising system effectiveness when system transfers performance requirement is certain.

The all or part of step that one of ordinary skill in the art will appreciate that in said method is carried out instruction related hardware by program and is completed, and described program can be stored in computer-readable recording medium, as read-only memory, disk or CD etc.Alternatively, all or part of step of above-described embodiment also can use one or more integrated circuit to realize, and correspondingly, each module/unit in above-described embodiment can adopt the form of hardware to realize, and the form of software function module also can be adopted to realize.The present invention is not restricted to the combination of the hardware and software of any particular form.

It should be noted that; the present invention also can have other various embodiments; when not deviating from the present invention's spirit and essence thereof; those of ordinary skill in the art can make various corresponding change and distortion according to the present invention, but these change accordingly and are out of shape the protection range that all should belong to the claim appended by the present invention.

Claims (10)

1. a coherent optical communication channel estimation methods, the method comprises:

Receiving terminal often receives frame data, the training sequence comprised according to present frame estimates the channel transfer functions of present frame, the channel transfer functions estimated is preserved as the initial estimation of the channel transfer functions of present frame;

Read the final estimation of the channel transfer functions of the former frame of present frame, as read, then the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, the channel transfer functions after weighted average is preserved as the final estimation of the channel transfer functions of present frame.

2. the method for claim 1, is characterized in that:

The initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprises:

The final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

3. the method for claim 1, is characterized in that:

The initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprises:

According to m frequency of the final estimation of the channel transfer functions of the former frame of current i-th frame phase value, and m frequency of the initial estimation of the channel transfer functions of current i-th frame phase value, estimate the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ik (), obtains θ _ithe estimated value of (k) n is the sum of frequency;

According to the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ithe estimated value of (k) phase rotating is carried out in the final estimation of the channel transfer functions of the former frame of current i-th frame, makes the phase place of the corresponding frequency of the initial estimation of the channel transfer functions of current i-th frame of phase alignment of each frequency of the channel transfer functions of the former frame of postrotational current i-th frame;

The initial estimation of the final estimation of the channel transfer functions of the former frame of current i-th frame through phase alignment and the channel transfer functions of current i-th frame is weighted on average, obtains the final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)e^{j{\widehat{\mathrm{\&theta;}}}_i\left(k\right)}+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

4. the method for claim 1, is characterized in that, also comprises:

The weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame is set according to following rule _i: accelerate the speed of following the trail of channel variation as needed, then increase the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i; As needs improve antimierophonic performance, then reduce the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i.

5. the method for claim 1, is characterized in that, also comprises:

Read the final estimation of the channel transfer functions of the former frame of present frame, as do not read, then using the final estimation of the initial estimation of the channel transfer functions of described present frame as the channel transfer functions of described present frame.

6. a coherent optical communication channel estimation system, this system comprises:

Initial estimation and preserve module, often receive frame data for receiving terminal, the training sequence comprised according to present frame estimates the channel transfer functions of present frame, the channel transfer functions estimated is preserved as the initial estimation of the channel transfer functions of present frame;

Final estimation and preservation module, for reading the final estimation of the channel transfer functions of the former frame of present frame, as read, then the initial estimation of the final estimation of the channel transfer functions of the former frame of described present frame and the channel transfer functions of present frame is weighted on average, the channel transfer functions after weighted average is preserved as the final estimation of the channel transfer functions of present frame.

7. system as claimed in claim 6, is characterized in that:

Final estimation and preservation module, initial estimation for the final estimation of the channel transfer functions of the former frame by described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprising:

The final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

8. system as claimed in claim 6, is characterized in that:

Final estimation and preservation module, initial estimation for the final estimation of the channel transfer functions of the former frame by described present frame and the channel transfer functions of present frame is weighted on average, using the final estimation of the channel transfer functions after weighted average as the channel transfer functions of present frame, comprising:

According to m frequency of the final estimation of the channel transfer functions of the former frame of current i-th frame phase value, and m frequency of the initial estimation of the channel transfer functions of current i-th frame phase value, estimate the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ik (), obtains θ _ithe estimated value of (k) n is the sum of frequency;

According to the phase difference θ of the channel transfer functions of the former frame of current i-th frame and the channel transfer functions of current i-th frame _ithe estimated value of (k) phase rotating is carried out in the final estimation of the channel transfer functions of the former frame of current i-th frame, makes the phase place of the corresponding frequency of the initial estimation of the channel transfer functions of current i-th frame of phase alignment of each frequency of the channel transfer functions of the former frame of postrotational current i-th frame;

The initial estimation of the final estimation of the channel transfer functions of the former frame of current i-th frame through phase alignment and the channel transfer functions of current i-th frame is weighted on average, obtains the final estimation of the channel transfer functions of current i-th frame for:

${\hat{H}}_i\left(k\right)=(1-{\mathrm{\&alpha;}}_i){\hat{H}}_{i-1}\left(k\right)e^{j{\widehat{\mathrm{\&theta;}}}_i\left(k\right)}+{\mathrm{\&alpha;}}_i{\tilde{H}}_i\left(k\right);$

Wherein, the final estimation of the channel transfer functions of the former frame of current i-th frame, it is the initial estimation of the channel transfer functions of current i-th frame; K represents frequency; α _ifor the weight coefficient of the initial estimation of the channel transfer functions of current i-th frame, 0< α _i≤ 1; I>=2.

9. system as claimed in claim 6, is characterized in that, also comprise:

Module is set, for arranging the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame according to following rule _i: accelerate the speed of following the trail of channel variation as needed, then increase the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i; As needs improve antimierophonic performance, then reduce the weight coefficient α of the initial estimation of the channel transfer functions of current i-th frame _i.

10. system as claimed in claim 6, is characterized in that:

Final estimation and preservation module, for reading the final estimation of the channel transfer functions of the former frame of present frame, as do not read, then using the final estimation of the initial estimation of the channel transfer functions of described present frame as the channel transfer functions of described present frame.