CN101729147A - Method and receiver for realizing phase synchronization of coherent light - Google Patents

Method and receiver for realizing phase synchronization of coherent light Download PDF

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Publication number
CN101729147A
CN101729147A CN200810171949A CN200810171949A CN101729147A CN 101729147 A CN101729147 A CN 101729147A CN 200810171949 A CN200810171949 A CN 200810171949A CN 200810171949 A CN200810171949 A CN 200810171949A CN 101729147 A CN101729147 A CN 101729147A
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described
signal
coherent light
phase error
phase
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CN200810171949A
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CN101729147B (en
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徐晓庚
乔耀军
杜晓
纪越峰
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华为技术有限公司
北京邮电大学
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Abstract

The embodiment of the invention discloses a method and a receiver for realizing phase synchronization of coherent light. The method comprises the following steps that analog/digital conversion of a signal acquired after frequency mixing of a received coherent light signal and a local oscillation signal is carried out and the converted frequency mixing signal comprises the frequency deviation and phase noise of the coherent light signal and the local oscillation signal; the phase error of the frequency mixing signal is extracted by means of logarithm and comprises the frequency deviation and the phase noise; and the phase error is removed from the frequency mixing signal. The method and the receiver extract the phase error acquired after frequency mixing of the received coherent light signal and the local oscillation signal by means of logarithm and then remove the extracted phase error from the frequency mixing signal, thereby realizing the phase synchronization of the received signal and the local oscillation signal, preventing the signal of a coherent communication system from generating phase ambiguity and increasing the accuracy of the phase synchronization and the demodulation efficiency of a receiving system.

Description

Phase locked method of a kind of realization coherent light and receiver

Technical field

The present invention relates to optical communication field, especially relate to phase locked method of a kind of realization coherent light and receiver.

Background technology

Along with growing continuously and fast of network bandwidth requirements in recent years, requirement to the single channel message transmission rate is more and more higher, therefore, possess the data capacity that promotes existing fiber, support the coherent light reception technique of advantages such as multiple modulation system, receiver sensitivity height to become the research focus of international optical communication field.Coherent light is meant that two bundle direction of vibration are identical, vibration frequency is identical, phase place is identical or phase difference keeps constant light, can produce interference in the zone that two bundle coherent lights meet.

The coherent light signal that the realization coherent optical communication need receive is identical with the local oscillation signal frequency and the phase place of receiver.But, (from 100KHz to 100MHz, do not wait) live width because the light that the present laser that uses sends generally has necessarily, thereby cause that certain phase error is arranged between received signal and the local oscillation signal.Therefore, adopt certain method to make the phase place of received signal and local oscillation signal become one of key technology of coherent optical communication synchronously, by numerous technical staff's broad research.

The method of available technology adopting phase estimation utilizes feed-forward to realize Phase synchronization.This method is specially:

Received signal is carried out analog/digital conversion (Analog-to-digital conversion, A/D conversion);

To promote biquadratic behind the signal that be converted to and the signal multiplication in last cycle;

Ask N length signals sum;

The argument of obtaining this signal is again divided by 4;

With the phase error in the phase error signal signal that elimination receives as feedback signal that obtains at last, thereby realize Phase synchronization.

In research and practice process to prior art, the present inventor finds that there is following problem in prior art:

Owing to adopt argument to carry out synchronously, can only detect the phase place of argument scope between [180 ° ,+180 °], when surpassing this scope, argument just can not solve well-determined phase place, can produce periodically many-valued problem, i.e. phase ambiguity, thus influence the demodulation efficient of receiving system.

Summary of the invention

The technical problem that the embodiment of the invention will solve provides phase locked method of a kind of realization coherent light and receiver, can avoid the coherent communication system signal to produce phase ambiguity, improves the demodulation efficient of Phase synchronization accuracy and receiving system.

For solving the problems of the technologies described above, embodiment provided by the present invention is achieved through the following technical solutions:

The phase locked method of a kind of realization coherent light:

The coherent light signal that receives and the signal after the local oscillation signal mixing are carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal; Utilize logarithm to extract the phase error of described mixed frequency signal, described phase error comprises described frequency shift (FS) and phase noise; From described mixed frequency signal, remove described phase error.

A kind of receiver comprises:

Converting unit is used for the coherent light signal that will receive and the signal after the local oscillation signal mixing and carries out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal; Extraction unit is used to utilize logarithm to extract the phase error of the mixed frequency signal after described converting unit is changed, and described phase error comprises described frequency shift (FS) and phase noise; Phasing unit is used for removing described phase error from described mixed frequency signal.

By technique scheme as can be seen, the phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing, from described mixed frequency signal, remove the phase error of being extracted again, thereby realize the synchronous of received signal and local oscillation signal phase place, can avoid the coherent communication system signal to produce phase ambiguity, improve the demodulation efficient of Phase synchronization accuracy and receiving system.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the method flow schematic diagram of the embodiment of the invention one;

Fig. 2 is the method flow schematic diagram of the embodiment of the invention two;

Fig. 3 is the method flow schematic diagram of the embodiment of the invention three;

Fig. 4 is the signal shunt schematic diagram of the embodiment of the invention three;

Fig. 5 is the parallel processing schematic diagram of three couples of signal boost M of embodiment of the invention power;

Fig. 6 is the structural representation of embodiment of the invention receiver;

Fig. 7 is another structural representation of embodiment of the invention receiver.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.

The embodiment of the invention is applicable to quaternary PSK (Quadrature Phase-Shift Keying, QPSK), M system phase-shift keying (M-ary Phase Shift Keying, M-ary PSK), the coherent demodulation system of M ary quadrature amplitude (M-ary Quadrature Amplitude Modulation, M-ary QAM) modulation type.

Embodiment one, describe in detail referring to Fig. 1, Fig. 1 is the method flow schematic diagram of present embodiment.

Step 101: the coherent light signal that receives and the signal after the local oscillation signal mixing are carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal.

The coherent light signal of transmitter emission behind receiver, is sent into 90 degree optical mixer units by Optical Fiber Transmission earlier usually, and local oscillation signal then is transfused to 90 degree optical mixer unit another port usually, and all the other two ports of frequency mixer can be set to 0, are about to its ground connection.After the mixing, usually the coherent light signal and the local oscillation signal that receive are imported balanced reciver respectively, then the output signal of balanced reciver is passed through filter respectively, and carrying out analog/digital conversion, the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal.

Coherent light signal and local oscillation signal are converted to figure pattern, are beneficial to follow-up computing.

Step 102: utilize logarithm to extract the phase error of described mixed frequency signal, described phase error comprises described frequency shift (FS) and phase noise.

Phase error refers to the error that exists between coherent light signal and the local oscillation signal can comprise frequency shift (FS) and phase noise etc.

To utilize logarithm to extract phase error between coherent light signal and the local oscillation signal through the mixed frequency signal of analog/digital conversion, logarithm can adopt natural logrithm, obviously, adopts other logarithms also not influence the realization of the embodiment of the invention.

The phase error that can extract coherent light signal according to natural logrithm is c k=lnA+j (4 Δ wkT s+ 4 Δ φ k), wherein, Δ w is the frequency shift (FS) of described coherent light signal and described local oscillation signal, and Δ φ is the phase noise of described coherent light signal and described local oscillation signal, and k represents k sampling period, and Ts refers to the sampling period, j is the unit of imaginary part in the plural number, A=s k 4, be a real number, S kRepresentative is in the information bit of k sampling instant, and information bit refers to that phase information institute is on the throne.

Utilize logarithm to extract phase error, then strengthened the large frequency-difference disposal ability, thereby avoided exceeding the argument scope in the prior art and the phase ambiguity that produces.

Step 103: from described mixed frequency signal, remove described phase error.

Removing described phase error can adopt multiplier to realize, with the phase error extracted and the mixed frequency signal elimination phase error that multiplies each other, promptly realized certainly, adopting other modes from described mixed frequency signal, to remove the realization that described phase error does not influence the embodiment of the invention yet synchronously.

Signal has synchronously been eliminated phase error, sends into follow-up equalizing circuit and data recovery circuit, carries out processing such as EDC (Electrical dispersion compensation), data recovery.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing, from described mixed frequency signal, remove the phase error of being extracted again, realize the synchronous of received signal and local oscillation signal phase place, can avoid the coherent communication system signal to produce phase ambiguity, improve the demodulation efficient of Phase synchronization accuracy and receiving system.

In the practical application, can carry out parallel processing to coherent light signal and local oscillation signal, second following examples describe the practical application flow process in detail.

Embodiment two, describe in detail referring to Fig. 2, Fig. 2 is the method flow schematic diagram of present embodiment.

Step 201: the coherent light signal that receives and the signal after the local oscillation signal mixing are carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal.

After the mixing, usually the coherent light signal and the local oscillation signal that receive are imported balanced reciver respectively, then the output signal of balanced reciver is passed through filter respectively, and carrying out analog/digital conversion, the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal.

Step 202: described mixed frequency signal is divided into two-way, one road input time delay device, the one tunnel utilizes logarithm to extract the phase error between the coherent light signal and local oscillation signal in the described mixed frequency signal.

Can mixed frequency signal be divided into two-way by power averaging by signal shunt, every road all comprises the complete information of coherent light signal and local oscillation signal; So that after in road mixed frequency signal from the two-way shunt, extracting described phase error, from the mixed frequency signal of another road time-delay, remove described phase error.

Utilize logarithm to extract the phase error of coherent light signal to the mixed frequency signal through analog/digital conversion, described logarithm can adopt natural logrithm, obviously, adopts other logarithms also not influence the realization of the embodiment of the invention.

Step 203: the phase error that is extracted is removed from the mixed frequency signal after the time-delay.

Removing described phase error can adopt multiplier to realize, the mixed frequency signal elimination phase error that multiplies each other after the phase error of Ti Quing and the time-delay just, realize certainly, adopting other modes to realize from mixed frequency signal, removing the realization that described phase error does not influence the embodiment of the invention yet synchronously.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing, from described mixed frequency signal, remove the phase error of being extracted again, realize the synchronous of received signal and local oscillation signal phase place, can avoid the coherent communication system signal to produce phase ambiguity, improve the Phase synchronization accuracy; And mixed frequency signal is divided into two-way, adopts parallel processing to carry out feed-forward and eliminate phase error, improve Synchronous Processing speed.

In the practical application, also need coherent light information is removed the processing of interference, three of following examples describe the practical application flow process in detail.

Embodiment three, describe in detail referring to Fig. 3, Fig. 3 is the method flow schematic diagram of present embodiment.

Step 301: the coherent light signal that receives and the signal after the local oscillation signal mixing are carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal.

After the mixing, usually the coherent light signal and the local oscillation signal that receive are imported balanced reciver respectively, then the output signal of balanced reciver is passed through filter respectively, and carrying out analog/digital conversion, the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal.If the coherent light signal that receives is Local oscillation signal is Wherein, m (t) is a noise signal, ω SBe the frequency of coherent light signal, It is the first phase of coherent light signal; ω LBe the frequency of local oscillation signal, Be the first phase of local oscillation signal, Ts refers to the sampling period, and k represents k sampling period, and j is the unit of imaginary part in the plural number.

Can 90 ° of desirable devices that Optical Hybrid is photomixing (ripple) device, wherein the coupler transfer function is: If the input signal of 90 ° of Optical Hybrid is respectively E 11, E 12, E 21, E 22, be output as E 33, E 34, E 43, E 44, E wherein 12, E 21Be zero, and Then have:

E → 33 E → 34 = 1 2 E → 22 - 1 2 E → 11 j 1 2 E → 22 + j 1 2 E → 11

E → 43 E → 44 = j 1 2 E → 22 - 1 2 E → 11 - 1 2 E → 22 + j 1 2 E → 11

Thereby can draw coherent light signal I, local oscillation signal Q is respectively

I = | E → 34 | 2 - | E → 33 | 2 = | j 1 2 E → 22 + j 1 2 E → 11 | 2 - | 1 2 E → 22 - 1 2 E → 11 | 2

= ( j 1 2 E → 22 + j 1 2 E → 11 ) ( j 1 2 E → 22 + j 1 2 E → 11 ) * - ( 1 2 E → 22 - 1 2 E → 11 ) ( 1 2 E → 22 - 1 2 E → 11 ) *

= ( j 1 2 E → 22 + j 1 2 E → 11 ) ( - j 1 2 E → 22 * - j 1 2 E → 11 * ) - ( 1 2 E → 22 - 1 2 E → 11 ) ( 1 2 E → 22 * - 1 2 E → 11 * )

= 1 4 ( | E → 22 | 2 + E → 22 E → 11 * + E → 11 E → 22 * + | E → 11 | 2 )

- 1 4 ( | E → 22 | 2 - E → 22 E → 11 * - E → 11 E → 22 * + | E → 11 | 2 )

= 1 2 ( E → 22 E → 11 * + E → 11 E → 22 * )

= Re ( E → 22 E → 11 * )

Q = | E → 43 | 2 - | E → 44 | 2 = | j 1 2 E → 22 - 1 2 E → 11 | 2 - | 1 2 E → 22 + j 1 2 E → 11 | 2

= ( j 1 2 E → 22 - 1 2 E → 11 ) ( j 1 2 E → 22 - 1 2 E → 11 ) * - ( - 1 2 E → 22 + j 1 2 E → 11 ) ( - 1 2 E → 22 + j 1 2 E → 11 ) *

= ( j 1 2 E → 22 - 1 2 E → 11 ) ( - j 1 2 E → 22 * - 1 2 E → 11 * ) - ( - 1 2 E → 22 + j 1 2 E → 11 ) ( - 1 2 E → 22 * - j 1 2 E → 11 * )

= 1 4 ( | E → 22 | 2 - j E → 22 E → 11 * + j E → 11 E → 22 * + | E → 11 | 2 )

- 1 4 ( | E → 22 | 2 + j E → 22 E → 11 * - j E → 11 E → 22 * + | E → 11 | 2 )

= 1 2 ( - j E → 22 E → 11 * + j E → 11 E → 22 * )

= Im ( E → 22 E → 11 * )

Thereby can obtain:

Wherein, Δ ω=ω SL, represent the frequency shift (FS) of described coherent light signal and described local oscillation signal, Represent the phase noise of described coherent light signal and described local oscillation signal, m (t) represents noise signal, and j is the unit of imaginary part in the plural number.

After the A/D variation, following formula can be changed into Each parameter meaning is the same.

Step 302: described mixed frequency signal is divided into A, B two-way, A road input time delay device, the B road utilizes logarithm to extract the phase error of described mixed frequency signal.

Can signal be divided into A, B two-way by power averaging by signal shunt, every road all comprises the complete information of coherent light signal and local oscillation signal.Referring to Fig. 4, Fig. 4 is the signal shunt schematic diagram of present embodiment.

Utilize logarithm to extract the phase error of coherent light signal to coherent light signal and local oscillation signal through analog/digital conversion, logarithm can adopt natural logrithm, obviously, adopts other logarithms also not influence the realization of the embodiment of the invention.

If a k=I k+ jQ k, be output as after the signal shunt shunt

Step 303: the processing of B road signal being removed interference.

The processing of remove disturbing can comprise the influence of removing information bit and remove noise effect etc., specifically processing can for: at first it is asked the M power, then averaged; Perhaps can for: will promote described signal behind the M power divided by M.

The value difference of M when using the different modulating form, M gets 4 when using the QPSK modulation format, and M gets 4 integral multiple when using M-ary PSK modulation format.With the QPSK modulation format is example, can obtain:

b k=<(a k) 4>

=<[s k?exp(jΔwkT s+jΔφ k)+m(kT s)] 4>

=<s k 4exp(j4ΔwkT s+j4Δφ k)>

+<4s k 3exp(j3ΔwkT s+j3Δφ k)m(kT s)>

+<6s k 2exp(j2ΔwkT s+j2Δφ k)m 2(kT s)>

+<4s kexp(jΔwkT s+jΔφ k)m 3(kT s)>

+<m 4(kT s)>

Because m k(kT s) be white Gaussian noise, so can ignore for its high-order term.Thereby obtain:

b k=<s k 4exp(j4ΔwkT s+j4Δφ k)>

+<4s k 3exp(j3ΔwkT s+j3Δφ k)m(kT s)>

In addition, can learn that second mean value in the following formula is zero, thereby can obtain: b according to the statistical property of signal k=<s k 4Exp (j4 Δ wT s+ j4 Δ φ k), wherein, A=s k 4, be a real number, S kRepresentative is in the information bit of k sampling instant, and information bit refers to that phase information institute is on the throne, and other each parameter meanings are the same.

Ask the M power can take binding signal splitter and multiplier to wait to B road signal and realize,, multiply each other then as earlier along separate routes with signal, along separate routes, multiply each other again again, can realize the quadruplicate purpose of signal boost, can adopt parallel processing technique, to improve the reaction speed and the disposal ability of system.Concrete grammar can be as shown in Figure 5, and Fig. 5 is the parallel processing schematic diagram to signal boost M power.

Step 304: utilize logarithm to extract phase error to B road signal.

Logarithm is an example with the natural logrithm, then has: c k=lnA+j (4 Δ wkT s+ 4 Δ φ k), wherein each parameter meaning is ditto described.

This step can be by FPGA look-up table (Look-up Table LUT) realizes.Because of designing the look-up table of much scales, and select processing speed and the phase locked precision that step-length can influence system of searching how long for use, and for example the scale of look-up table is big more, and it is more little to search step-length, phase locked precision is just high more, but the processing speed of system can descend.Therefore, the scale of look-up table and search step-length and can compromise according to actual conditions and choose, but do not influence the realization of the embodiment of the invention.

Relatively low or system requires in the relatively low system Phase synchronization in system's speed, as the 10G system, perhaps channel condition is preferably in the 40G system (system all smaller as newly-built various damages), also can be to the output summation of N phase error, and then it is averaged, to improve accuracy.

Step 305: the imaginary part of extracting phase error.

Extract imaginary part and obtain d k=Im (c k)/4=Δ wkT s+ Δ φ k

Step 306: it is on the index of exponential function at the end that phase error is adjusted to e.

The phase error f that extracts k=exp -1(j Δ wkT s+ j Δ φ k).

Step 307: the phase error that is extracted is removed from the A road signal after the time-delay, realize the synchronous of coherent light signal and local oscillation signal.

After removing the phase error in the coherent light signal, then coherent light signal and local oscillation signal have been carried out synchronously.

Removing described phase error can adopt multiplier to realize, with the phase error extracted and the mixed frequency signal elimination phase error that multiplies each other, realize certainly, adopting other modes to realize from mixed frequency signal, removing the realization that described phase error does not influence the embodiment of the invention yet synchronously.

The delay time of A road delayer should equal the summation of step 303 signal processing time to the step 306, and its input signal is Output signal is R is the sampling period of time-delay.

In the embodiment of the invention, when adopting multiplier, input signal is respectively A road signal F with B road signal k=exp -1(j Δ wkT s+ j Δ φ k), be output as g k=s k(nT s), each parameter meaning is with aforementioned.

Can pass through DSP (Digital Signal Processor to step 303 to the step 306 that the road signal that extracts phase error is handled, digital signal processor) or FPGA (Field-ProgrammableGate Array, programmable gate array) realize, thus can integrated difficulty and the system's implementation complexity of mitigation system.

And, to the enforcement of step 306, all can use filter to carry out filtering in step 303, the influence of the noise component(s) in the erasure signal as much as possible, thereby the signal to noise ratio of raising system.Can adopt some present main flow filters to realize filter function.Certainly, under the bigger situation of channel signal to noise ratio, filter can omit according to actual conditions.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing, from described mixed frequency signal, remove the phase error of being extracted again, realize the synchronous of received signal and local oscillation signal phase place, can avoid the coherent communication system signal to produce phase ambiguity, improve the Phase synchronization accuracy; And mixed frequency signal is divided into two-way, adopts parallel processing to carry out feed-forward and eliminate phase error, improve Synchronous Processing speed; And mixed frequency signal removed the processing of interference, further improve the demodulation efficient of phase locked accuracy and receiving system.

Need to prove, for aforesaid each method embodiment, for simple description, so it all is expressed as a series of combination of actions, but those skilled in the art should know, the present invention is not subjected to the restriction of described sequence of movement, because according to the present invention, some step can adopt other orders or carry out simultaneously.Secondly, those skilled in the art also should know, the embodiment described in the specification all belongs to preferred embodiment, and related action and module might not be that the present invention is necessary.

In the above-described embodiments, the description of each embodiment is all emphasized particularly on different fields, do not have the part that describes in detail among certain embodiment, can be referring to the associated description of other embodiment.

More than provide a kind of realization coherent light phase locked method, the embodiment of the invention also provides a kind of receiver.

A kind of receiver 500, referring to Fig. 6, Fig. 6 is the structural representation of embodiment of the invention receiver, comprising:

Converting unit 501 is used for the coherent light signal that will receive and the signal after the local oscillation signal mixing and carries out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal; Coherent light signal and local oscillation signal are converted to figure pattern, are beneficial to follow-up computing.

Extraction unit 502 is used to utilize logarithm to extract the phase error of the mixing after described converting unit 501 is changed; Phase error refers to the error between coherent light signal and the local oscillation signal, can comprise frequency shift (FS) and phase noise etc., and logarithm can adopt natural logrithm, obviously, adopts other logarithms also not influence the realization of the embodiment of the invention.

Phasing unit 503 is used for removing the described phase error that extraction unit 502 extracts from described mixed frequency signal.

Described receiver can also comprise that except above-mentioned converting unit 501, extraction unit 502, phasing unit 503 referring to Fig. 7, Fig. 7 is another structural representation of embodiment of the invention receiver:

Remove interference units 504, be used for before extraction unit 502 utilizes logarithm to extract the phase error of mixed frequency signal, the signal that has carried out analog/digital conversion is removed to disturb handle, can comprise following subelement:

M power unit 505, the mixed frequency signal that is used for converting unit was changed promotes the M power, and described M is 4 integral multiple;

Mean value unit 506 is used for the mixed frequency signal that M power unit 505 promotes the M power is averaged.

Perhaps, remove interference units 504 and can comprise following subelement:

M power unit 505, the mixed frequency signal that is used for converting unit was changed promotes the M power, and described M is 4 integral multiple;

Ask merchant unit 507, be used for M power unit 505 is promoted the mixed frequency signal of M power divided by M.

Described influence and the The noise that interference units 504 can be removed information bit, the accuracy of raising receiving system processing signals removed.

Described receiver can also comprise:

Branching unit, be used for before the mixed frequency signal that has carried out analog/digital conversion being removed the interference processing except that interference units, mixed frequency signal after the converting unit conversion is divided into two-way, one road input time delay device, the one tunnel utilizes logarithm to extract the phase error of described mixed frequency signal.

Removing phase error can adopt multiplier to realize, with the elimination phase error that multiplies each other of the mixed frequency signal after the phase error extracted and the time-delay, realize certainly, adopting other modes to realize from mixed frequency signal, removing the realization that described phase error does not influence the embodiment of the invention yet synchronously.

The phase error of signal after coherent light signal that the embodiment of the invention is utilized logarithm to extract to receive and the local oscillation signal mixing, from described mixed frequency signal, remove the phase error of being extracted again, realize the synchronous of received signal and local oscillation signal phase place, can avoid the coherent communication system signal to produce phase ambiguity, improve the Phase synchronization accuracy; And mixed frequency signal is divided into two-way, adopts parallel processing to carry out feed-forward and eliminate phase error, improve Synchronous Processing speed; And mixed frequency signal removed the processing of interference, further improve the demodulation efficient of phase locked accuracy and receiving system.

One of ordinary skill in the art will appreciate that, realize all or part of flow process in the foregoing description method, be to instruct relevant hardware to finish by computer program, described program can be stored in the computer read/write memory medium, this program can comprise the flow process as the embodiment of above-mentioned each side method when carrying out.Wherein, described storage medium can be magnetic disc, CD, read-only storage memory body (Read-OnlyMemory, ROM) or at random store memory body (Random Access Memory, RAM) etc.

More than phase locked method of a kind of realization coherent light and receiver that the embodiment of the invention provided are described in detail, used specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (13)

1. realize the phase locked method of coherent light for one kind, it is characterized in that:
The coherent light signal that receives and the signal after the local oscillation signal mixing are carried out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal;
Utilize logarithm to extract the phase error of described mixed frequency signal, described phase error comprises described frequency shift (FS) and phase noise;
From described mixed frequency signal, remove described phase error.
2. the phase locked method of realization coherent light according to claim 1 is characterized in that, described phase error by logarithm extraction mixed frequency signal is specially:
Extract the phase error of mixed frequency signal by natural logrithm.
3. the phase locked method of realization coherent light according to claim 2 is characterized in that, described phase error by natural logrithm extraction mixed frequency signal is specially:
Extract the phase error c of mixed frequency signal according to natural logrithm k=ln A+j (4 Δ wkT s+ 4 Δ φ k), wherein, Δ w is the frequency shift (FS) of described coherent light signal and described local oscillation signal, and Δ φ is the phase noise of described coherent light signal and described local oscillation signal, and k represents k sampling period, and Ts refers to the sampling period, j is the unit of imaginary part in the plural number, A=s k 4, be a real number, S kRepresentative is in the information bit of k sampling instant.
4. the phase locked method of realization coherent light according to claim 1 is characterized in that, also comprises before the described phase error of utilizing logarithm to extract described coherent light signal:
The described coherent light signal of the process analog/digital conversion that receives is removed the processing of interference.
5. the phase locked method of realization coherent light according to claim 4 is characterized in that, the described processing that the coherent light signal that receives is removed interference is specially:
Coherent light signal is promoted the M power;
Divided by M, described M is 4 integral multiple with the described signal behind the lifting M power.
6. the phase locked method of realization coherent light according to claim 4 is characterized in that, the described processing that the coherent light signal that receives is removed interference is specially:
Coherent light signal is promoted the M power;
To the described signal averaged behind the lifting M power, described M is 4 integral multiple.
7. according to claim 5 or the phase locked method of 6 described realization coherent lights, it is characterized in that described M value is 4 when using the quaternary PSK modulation format.
8. according to the phase locked method of each described realization coherent light of claim 1 to 6, it is characterized in that, before the described phase error of utilizing logarithm to extract described coherent light signal, also comprise:
Will through comprising of analog/digital conversion described coherent light signal and local oscillation signal signal carry out the shunt parallel processing; Correspondingly,
Describedly from described mixed frequency signal, remove described phase error and be specially:
The described phase error that to obtain from one road mixed frequency signal of described shunt is removed from another road mixed frequency signal.
9. according to the phase locked method of each described realization coherent light of claim 1 to 6, it is characterized in that, described utilize the phase error that logarithm extracts described coherent light signal after, also comprise before from described mixed frequency signal, removing described phase error:
Extract the imaginary part of described phase error;
Regulate described imaginary part to being on the index of exponential function at the end with e.
10. a receiver is characterized in that, comprising:
Converting unit is used for the coherent light signal that will receive and the signal after the local oscillation signal mixing and carries out analog/digital conversion, and the mixed frequency signal after the conversion comprises the frequency shift (FS) and the phase noise of described coherent light signal and described local oscillation signal;
Extraction unit is used to utilize logarithm to extract the phase error of the mixed frequency signal after described converting unit is changed, and described phase error comprises described frequency shift (FS) and phase noise;
Phasing unit is used for removing described phase error from described mixed frequency signal.
11. receiver according to claim 10 is characterized in that, also comprises:
Remove interference units, be used for before described extraction unit utilizes logarithm to extract the phase error of mixed frequency signal, the signal that has carried out analog/digital conversion is removed to disturb handle.
12. receiver according to claim 11 is characterized in that, the described interference units of removing specifically comprises:
M power unit, the mixed frequency signal that is used for described converting unit was changed promotes the M power, and described M is 4 integral multiple;
The mean value unit is used for the mixed frequency signal of described M power unit lifting M power is averaged.
13. receiver according to claim 11 is characterized in that, the described interference units of removing specifically comprises:
M power unit, the mixed frequency signal that is used for described converting unit was changed promotes the M power, and described M is 4 integral multiple;
Ask the merchant unit, be used for described M power unit is promoted the mixed frequency signal of M power divided by M.
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Cited By (3)

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CN102647381A (en) * 2012-03-22 2012-08-22 中兴通讯股份有限公司 Method and device for elevating frequency deviation in MPSK (Mary Phase Shift Keying) coherent light communication system
WO2013107165A1 (en) * 2012-01-16 2013-07-25 中兴通讯股份有限公司 Deflection detection method and system for output signals of coherent optical receiver
CN107409000A (en) * 2015-04-10 2017-11-28 华为技术有限公司 A kind of coherent source offset estimation and the coherent receiver of compensation, method and system

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CN1004463B (en) * 1987-07-10 1989-06-07 东南大学 Heterodyne coherent-light communication method
CN1497546A (en) * 2002-10-23 2004-05-19 松下电器产业株式会社 Coherent light source and its driving method
JP4531740B2 (en) * 2006-12-15 2010-08-25 富士通株式会社 Coherent optical receiver

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Publication number Priority date Publication date Assignee Title
WO2013107165A1 (en) * 2012-01-16 2013-07-25 中兴通讯股份有限公司 Deflection detection method and system for output signals of coherent optical receiver
CN102647381A (en) * 2012-03-22 2012-08-22 中兴通讯股份有限公司 Method and device for elevating frequency deviation in MPSK (Mary Phase Shift Keying) coherent light communication system
CN107409000A (en) * 2015-04-10 2017-11-28 华为技术有限公司 A kind of coherent source offset estimation and the coherent receiver of compensation, method and system
CN107409000B (en) * 2015-04-10 2019-05-28 华为技术有限公司 A kind of coherent receiver, the method and system of coherent source offset estimation and compensation

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