CN101938438B - Optical signal generating and receiving methods and devices and optical transmission system - Google Patents
Optical signal generating and receiving methods and devices and optical transmission system Download PDFInfo
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Abstract
The embodiment of the invention relates to the field of communication and particularly discloses an optical signal generating method, an optical signal receiving method, an optical signal generating device, an optical signal receiving device and an optical transmission system. The optical signal generation method comprises: coding data in a differential manner to obtain first differentially coded data; coding the first differentially coded data in a differential manner to obtain second differentially coded data; and performing phase modulation on an optical carrier by using the second differentially coded data to obtain a modulation optical signal. With the optical signal generating method and the optical signal receiving method of the invention, a complex frequency offset control circuit and a phase estimation module are saved, but data transmitted by a transmitting end can be well restored from the modulation optical signal when a receiving end receives the modulation optical signal.
Description
Technical field
The present invention relates to the communications field, relate in particular to method, device and the optical transmission system of a kind of light signal generating and reception.
Background technology
In recent years, highly sensitive owing to having advantages of, selectivity good, coherent optical communication technology is widely used in the arterial grid of large capacity, long distance.Coherent modulation and heterodyne Detection Technique in coherent optical communication, have mainly been utilized.So-called coherent modulation, the signal that will transmit in transmitting terminal utilization exactly changes relevant light frequency, phase place and amplitude, obtains flashlight; So-called Heterodyne detect, the local oscillator light and the flashlight that at receiving terminal, utilize local oscillator light source to produce exactly carry out mixing in frequency mixer, obtain the intermediate-freuqncy signal changing by identical rule with signal light frequency, phase place and amplitude; Intermediate-freuqncy signal just obtains baseband signal after entering demodulator demodulation.If the frequency of light carrier when control local oscillator light frequency makes it modulate with transmitting terminal is identical, the frequency of the difference frequency signal obtaining after mixing is zero, directly obtains baseband signal, and this detection mode is called homodyne detection.
In adopting the coherent optical communication system of phase-modulation, at transmitting terminal, utilize the phase place of the defeated baseband signal modulated optical carrier of tendency to develop, obtain flashlight, after receiving terminal adopts heterodyne detection method that flashlight is converted into intermediate-freuqncy signal, carry out again secondary demodulation and obtain baseband signal, or adopt the method for zero-difference detection that flashlight is converted into baseband signal.Figure 1A shows the structure of a kind of optical sender of the prior art, and laser produces the good light carrier of coherence, and the phase place that then modulator removes modulated optical carrier by the baseband signal of input obtains flashlight and sends.Figure 1B shows a kind of structure of optical receiver, it adopts the method for zero-difference detection that flashlight is converted into baseband signal, 90 degree frequency mixers carry out mixing by flashlight and local oscillator light, and then survey with the light signal that balance detection device 1 and the mixing of 2 pairs 90 degree frequency mixers of balance detector obtain, obtain I signal and the Q signal of analog baseband signal, wherein I signal and Q signal are two components of analog baseband signal, with analog to digital converter analog baseband signal, be converted to digital baseband signal again, phase calculation module is calculated the phase place of digital baseband signal, obtain phase signal, finally with decoder, phase signal is decoded and obtained data-signal.This receiver adopts the method for zero-difference detection, so require the light carrier of local oscillator light and transmitting terminal strictly synchronous, be Frequency Synchronization and Phase synchronization, but in reality, be difficult to accomplish this strict synchronous, in Figure 1B, need in phase estimating device, adopt complicated algorithm to estimate the phase place of digital baseband signal, and the result that estimation is obtained is done on average in averager, averager is given decoder by the result obtaining, in decoder, make the phase rotating of digital baseband signal, to eliminate the frequency difference of local oscillator light and transmitting terminal light carrier and the impact differing.
The present inventor finds in research process, in prior art, at least there are the following problems: the optical receiver of prior art, though can eliminate the frequency difference of local oscillator light and transmitting terminal light carrier and differ produced impact by complicated algorithm, but it cannot solve the phase fuzzy problem existing due to phase-modulation itself, cause making a mistake when decoding.
Summary of the invention
The embodiment of the present invention provides a kind of method of reseptance of light signal, comprising:
Receive local oscillator light and modulated light signal, and described modulated light signal and local oscillator light are carried out to mixing, obtain the light signal after mixing, wherein, it is resulting that described modulated light signal is that initial data is modulated onto on light carrier after twice differential coding;
Light signal after mixing is surveyed, obtained analog baseband signal;
Described analog baseband signal is carried out to analog-to-digital conversion, obtain digital baseband signal;
Phase place to described digital baseband signal is adjudicated, and the phase information inverse mapping that judgement is obtained is Bit data;
Described Bit data is carried out to differential decoding, obtain the first decoded data;
Described the first decoded data is carried out to differential decoding, obtain described initial data.
The embodiment of the present invention also provides a kind of method of reseptance of light signal, it is characterized in that, comprising:
Receive local oscillator light and modulated light signal, and described modulated light signal and local oscillator light are carried out to mixing, obtain the light signal after mixing, wherein, it is resulting that described modulated light signal is that initial data is modulated onto on light carrier after twice differential coding;
Light signal after mixing is surveyed, obtained analog baseband signal;
Described analog baseband signal is carried out to analog-to-digital conversion, obtain digital baseband signal;
The digital baseband signal that the conjugated signal time delay of Contemporary Digital baseband signal one is clapped to rear and next bat multiplies each other, and obtains the first baseband signal;
The first baseband signal that the conjugated signal time delay of current the first baseband signal one is clapped to rear and next bat multiplies each other, and obtains the second baseband signal;
Phase place to described the second baseband signal is adjudicated, and the phase information inverse mapping that judgement is obtained is described initial data.
The embodiment of the present invention also provides a kind of method of reseptance of light signal, comprising:
Receive local oscillator light and modulated light signal, and described modulated light signal and local oscillator light are carried out to mixing, obtain the light signal after mixing, wherein, it is resulting that described modulated light signal is that initial data is modulated onto on light carrier after twice differential coding;
Light signal after mixing is surveyed, obtained analog baseband signal;
Described analog baseband signal is carried out to analog-to-digital conversion, obtain digital baseband signal;
The phase place of calculating described digital baseband signal, obtains phase signal;
The phase signal that current phase signal time delay one is clapped to rear and next bat is done mould 2 π subtractions, obtains the first phase signal;
The first phase signal that current the first phase place signal lag one is clapped to rear and next bat is done mould 2 π subtractions, obtains the second phase signal.
Described the second phase signal is adjudicated, obtain described initial data.
The embodiment of the present invention also provides a kind of receiving system of light signal, comprising:
Frequency mixer, be used for receiving local oscillator light and modulated light signal, and described local oscillator light and described modulated light signal are carried out to mixing, obtain the light signal after mixing, wherein, to be that initial data is modulated onto on light carrier after twice differential coding resulting for described modulated light signal;
Detecting module, for the light signal after described mixing is surveyed, obtains analog baseband signal;
Analog to digital converter, for described analog baseband signal is carried out to analog-to-digital conversion, obtains digital baseband signal;
Judging module, adjudicates for the phase place to described digital baseband signal, and the phase information inverse mapping that judgement is obtained is Bit data;
The first differential decoding module, for described Bit data is carried out to differential decoding, obtains the first decoded data;
The second differential decoding module, for described the first decoded data is carried out to differential decoding, obtains described initial data.
The embodiment of the present invention also provides a kind of receiving system of light signal, comprising:
Frequency mixer, be used for receiving local oscillator light and modulated light signal, and described local oscillator light and described modulated light signal are carried out to mixing, obtain the light signal after mixing, wherein, to be that initial data is modulated onto on light carrier after twice differential coding resulting for described modulated light signal;
Detecting module, for the light signal after described mixing is surveyed, obtains analog baseband signal;
Analog-to-digital conversion module, for described analog baseband signal is carried out to analog-to-digital conversion, obtains digital baseband signal;
The first conjugate module, for calculating the conjugated signal of described digital baseband signal;
The first time delay module, for the conjugated signal time delay of described digital baseband signal one is clapped, obtains the first time delayed signal;
The first multiplier, for the digital baseband signal of described the first time delayed signal and described next bat of digital baseband signal is multiplied each other, obtains the first baseband signal;
The second conjugate module, for calculating the conjugated signal of described the first baseband signal;
The second time delay module, for the conjugated signal time delay of described the first baseband signal one is clapped, obtains the second time delayed signal;
The second multiplier, for the first baseband signal of described the second time delayed signal and described first next bat of baseband signal is multiplied each other, obtains the second baseband signal;
Judging module, for the phase place of described the second baseband signal is adjudicated, and the phase information inverse mapping that judgement is obtained is described initial data.
The embodiment of the present invention also provides a kind of receiving system of light signal, comprising:
Frequency mixer, be used for receiving local oscillator light and modulated light signal, and described local oscillator light and described modulated light signal are carried out to mixing, obtain the light signal after mixing, wherein, to be that initial data is modulated onto on light carrier after twice differential coding resulting for described modulated light signal;
Detecting module, for the light signal after described mixing is surveyed, obtains analog baseband signal;
Analog-to-digital conversion module, for described analog baseband signal is carried out to analog-to-digital conversion, obtains digital baseband signal;
Phase calculation module, for calculating the phase place of described digital baseband signal, obtains phase signal;
The first time delay module, for described phase signal time delay one is clapped, obtains the first time delayed signal;
The first subtracter, for the phase signal of described the first time delayed signal and described next bat of phase signal being done to mould 2 π subtractions, obtains the first phase signal;
The second time delay module, for described the first phase place signal lag one is clapped, obtains the second time delayed signal;
The second subtracter, for the first phase signal of described the second time delayed signal and described first next bat of phase signal is done to mould 2 π subtractions, obtains the second phase signal;
Judging module, for described the second phase signal is adjudicated, obtains described initial data.
The embodiment of the present invention also provides a kind of optical transmission system, comprises optical signal generation apparatus and above-mentioned any light signal receiving;
Described optical signal generation apparatus comprises:
The first differential coding module, for initial data is carried out to differential coding, obtains the first differential coding data;
The second differential coding module, for described the first differential coding data are carried out to differential coding, obtains the second differential coding;
Modulator, for according to the second differential coding data, light carrier being carried out to phase-modulation, obtains modulated light signal.
In the embodiment of the present invention, the data of needs transmission are carried out to differential coding twice, then by the data after twice differential coding, go the phase place of modulated optical carrier, the phase information of the modulated light signal finally obtaining is not the data that direct correspondence will be transmitted, but the data that the phase information of modulated light signal obtains after the twice differential decoding data that just correspondence is transmitted, therefore make receiving terminal adopt local oscillator light and modulated light signal to carry out the digital baseband signal obtaining after the processing such as mixing, need to carry out twice differential decoding and just can recover the data that transmitting terminal transmits, the process of twice decoding not only can be eliminated the asynchronous phase fuzzy problem causing of phase place due to local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency due to local oscillator light and transmitting terminal light carrier, make the realization of receiving terminal receiving system simple.
Accompanying drawing explanation
Accompanying drawing described herein is used to provide a further understanding of the present invention, forms the application's a part, does not form limitation of the invention.
Figure 1A shows the structural representation of optical sender in prior art;
Figure 1B shows the structural representation of optical receiver in prior art;
Fig. 2 shows the structural representation of optical signal generation apparatus in the embodiment of the present invention;
Fig. 3 A shows the structural representation of differential encoder in the embodiment of the present invention;
Fig. 3 B shows the structural representation of differential decoder in the embodiment of the present invention;
Fig. 4 shows the first structural representation of light signal receiving in the embodiment of the present invention;
Fig. 5 shows the second structural representation of light signal receiving in the embodiment of the present invention;
Fig. 6 shows the 3rd structural representation of light signal receiving in the embodiment of the present invention;
Fig. 7 shows the schematic flow sheet of light signal generating method in the embodiment of the present invention;
Fig. 8 shows the first pass schematic diagram of light signal method of reseptance in the embodiment of the present invention;
Fig. 9 shows the second schematic flow sheet of light signal method of reseptance in the embodiment of the present invention;
Figure 10 shows the 3rd schematic flow sheet of light signal method of reseptance in the embodiment of the present invention.
Embodiment
For the ease of persons skilled in the art, understand and realize the present invention, now describing by reference to the accompanying drawings embodiments of the invention.At this, schematic description and description of the present invention is used for explaining the present invention, but not as a limitation of the invention.
Below in conjunction with drawings and Examples, technical scheme of the present invention is described.
The embodiment of the present invention provides a kind of generation device of light signal, and its structure as shown in Figure 2, comprising: 201, the second differential coding unit 202, the first differential coding unit, modulator 203.
The first 201 pairs of differential coding unit data are carried out differential coding, obtain the first differential coding data, and then carry out differential coding by 202 pairs of the second differential coding unit the first differential coding data, obtain the second differential coding data, modulator 203 use the second differential coding data are carried out phase-modulation to light carrier, obtain modulated light signal.The generation device of the light signal of the embodiment of the present invention can further include the laser for generation of light carrier.
Phase-modulation is to utilize the out of phase of carrier wave to characterize the data message of input, for a M=2
k(K=1,2,3 ...) phase-modulation of system, it is exactly by the M kind phase place of carrier wave, to characterize the data message of input, every K position Bit data is mapped to a phase place of carrier wave when modulating.Wherein, K position Bit data has represented a symbol of M system; The K position occupied time span of Bit data is referred to as symbol period, and each symbol period is referred to as a bat; The M kind phase place of carrier wave is referred to as main value phase place.
In the embodiment of the present invention, modulator 203 is by the second differential coding data of input, the phase place of light carrier to be modulated, and it can adopt BPSK, QPSK, 8PSK modulator etc.In the present embodiment, for adopting which kind of modulator not do concrete restriction, as long as the modulator adopting has the function of phase-modulation.
The first differential coding unit in the embodiment of the present invention and the second coding unit all can adopt the differential encoder of structure shown in Fig. 3 A to realize.Shown in Fig. 3 A, the encoder of structure comprises adder and delay unit.Delay unit is by the current output Y of adder
[N]the input X with next bat is delivered in adder in time delay one after clapping
[N+1]do the addition of mould M, obtain the output Y of next bat
[N+1],
the addition that represents mould M.Wherein, M is the system number of the phase-modulation that adopts of modulator, if the phase-modulation of 4 systems that phase-modulator adopts, the M is here just 4; The addition of mould M refers to two numbers is added, then the result of addition obtained to the process of remainder divided by M; Inputing or outputing of each bat is all symbols for M system, i.e. the input of each bat is (as X
[N+1]) are all K position Bit datas, the output of each bat is (as Y
[N+1]) be also K position Bit data.For example, current output Y
[N]be two Bit datas (10), the input X of next bat
[N+1]be two Bit datas (11), they done the addition of mould 4, be equivalent to (2+3) divided by 4, obtain remainder 1, the output Y of next bat
[N+1]be two Bit datas (01).
In the prior art, differential coding is a kind of common technology, therefore the first differential coding unit in the present embodiment is except adopting the differential encoder of structure shown in Fig. 3 A, can also adopt existing various differential encoder, and the present embodiment is not limited.
In the described optical signal generation apparatus of a specific embodiment, what modulator adopted is qpsk modulator, and what the first coding unit and the second coding unit adopted is all differential encoders of structure shown in Fig. 3 A.The concrete example that this optical signal generation apparatus produces light signal is as follows:
If desired the data of transmission are " 01111011000111 ", the first differential coding unit carries out differential coding to it, the the first differential coding data that obtain are " 01001001011001 ", and then with the second differential coding unit, it is carried out to differential coding, the the second differential coding data that obtain are " 01011100011100 ", then qpsk modulator is modulated the phase place of light carrier by the second differential coding data, the phase place that is light carrier by above-mentioned the second differential coding data-mapping, be respectively: 3 π/4, 3 π/4, 7 π/4, π/4, 3 π/4, 7 π/4, π/4.
It should be noted that, the mapping relations that above-mentioned qpsk modulator adopts are: set of signals { 00,01,10,11} is mapped as set { π/4,3 π/4 of 4 kinds of phase places compositions of light carrier, 5 π/4,7 π/4}, in another embodiment, qpsk modulator can also adopt following mapping relations: by set of signals { 00,01,10,11} is mapped as the set { 0 of 4 kinds of phase places compositions of light carrier, pi/2,3 pi/2s, π }.
In the present embodiment, the data of needs transmission are carried out to differential coding twice, then by the data after twice differential coding, go the phase place of modulated optical carrier, the phase information of the modulated light signal finally obtaining is not the data that direct correspondence will be transmitted, but the data that the phase information of modulated light signal obtains after the twice differential decoding data that just correspondence is transmitted, therefore make receiving terminal adopt local oscillator light and modulated light signal to carry out the digital baseband signal obtaining after the processing such as mixing, need to carry out twice differential decoding and just can recover the data that transmitting terminal transmits, the process of twice decoding not only can be eliminated the asynchronous phase fuzzy problem causing of phase place due to local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency due to local oscillator light and transmitting terminal light carrier, make the realization of receiving terminal receiving system simple.
The embodiment of the present invention also provides a kind of receiving system of light signal, the modulated light signal producing for receive the optical signal generation apparatus of structure shown in Fig. 2 at receiving terminal, and this modulated light signal is processed to the data that recover transmission, its structure as shown in Figure 4, comprising: frequency mixer 401, detecting module 402, analog to digital converter 403, judging module 404, the first differential decoding module 405, the second differential decoding module 406.
After 402 pairs of mixing of detecting module, obtain light signal and survey, obtain two components of analog baseband signal: I signal and Q signal, analog baseband signal can be expressed as: I+jQ.In the present embodiment, detecting module 402 can be comprised of balance detection device 1 and balance detector 2, and the light signal of two balance detection devices after to mixing carries out balance detection, obtains respectively I signal and and the Q signal of analog baseband signal.
The analog baseband signal that analog to digital converter 403 obtains detecting module 402 carries out analog-to-digital conversion, obtains digital baseband signal.Digital signal base-band signal is complex signal, has two components to be respectively I
ksignal and Q
ksignal, complex signal can be expressed as: I
k+ jQ
k.
The phase place of 404 pairs of digital baseband signals of judging module is adjudicated, and the phase information inverse mapping that judgement is obtained is Bit data.Concrete, the phase place of 404 pairs of digital baseband signals of judging module is adjudicated, and the modulation system then adopting according to transmitting terminal, carries out inverse mapping the phase information obtaining.For example, what at transmitting terminal, adopt is QPSK modulation system, the mapping relations that adopt are: set of signals 00,01,10,11} is mapped to phase sets { π/4 of carrier wave, 3 π/4,5 π/4,7 π/4}, herein, 404 of judging module are according to this mapping relations of QPSK modulation system, the phase information inverse mapping that judgement is obtained is Bit data: phase place π/4 inverse mapping is Bit data 00, phase place 3 π/4 inverse mappings are Bit data 01, and phase place 5 π/4 inverse mappings are Bit data 10, and phase place 7 π/4 inverse mappings are Bit data 11.
The Bit data that the first 405 pairs of differential decoding modules judging module 403 obtains carries out differential decoding, obtains the first decoded data.Second 406 pairs of differential decoding modules the first decoded data carries out differential decoding, obtains initial data, and the initial data that the second differential decoding module 406 obtains is the data of transmitting terminal transmission.The first differential decoding unit and the second decoding unit can adopt the differential decoder of structure shown in Fig. 3 B, also can adopt differential decoder of the prior art.Differential decoder shown in Fig. 3 B comprises a delay unit and subtracter, delay unit is delivered in subtracter and is done mould M subtraction with the input of next bat after current input time delay one is clapped, obtain the output of next bat, wherein, mould M subtraction is the inverse operation of mould M addition, mould M subtraction refers to that the result that two numbers are subtracted each other obtains remainder divided by M, specific practice is to subtract each other result that rear judgement subtracts each other whether between 0～M, if not, after the result of subtracting each other adds M as the result of the subtraction of mould M, if the result of subtracting each other is between 0～M, using the result of subtracting each other directly as the result of the subtraction of mould M, M is the system number of the phase-modulation that in transmitting terminal, modulator adopts, if phase-modulator adopts the phase-modulation of 4 systems, the M is here just 4, inputing or outputing of each bat is all symbols for M system, i.e. the input of each bat is all K position Bit datas, and the output of each bat is also K position Bit data.For example, current two Bit datas (11) that are input as, next bat be input as two Bit datas (01), they are done the subtraction of mould 4, be equivalent to 2-3+4, obtain 3, next bat is output as two Bit datas (11).
The light signal receiving that the embodiment of the present invention provides, due to the digital baseband signal obtaining is carried out to differential decoding twice, therefore not only can eliminate the asynchronous phase fuzzy problem causing of phase place between local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency between local oscillator light and transmitting terminal light carrier, and the light signal receiving that the embodiment of the present invention provides does not need frequency deviation control circuit and phase estimation module, but still can guarantee the receptivity of light signal receiving.
The embodiment of the present invention also provides a kind of receiving system of light signal, the modulated light signal producing for receive the optical signal generation apparatus of structure shown in Fig. 2 at receiving terminal, and this modulated light signal is processed and recovered the data that transmitting terminal transmits, its structure as shown in Figure 5, comprising: frequency mixer 501, detecting module 502, analog to digital converter 503, the first conjugation computing unit 504, the first delay unit 505, the first multiplier 506, the second conjugation computing unit 507, the second delay unit 508, the second multiplier 509, judging module 510.Wherein, frequency mixer 501, detecting module 502, analog to digital converter 503 are identical respectively with frequency mixer 401, detecting module 402, analog to digital converter 403 in Fig. 4 shown device, repeat no more here.
The first conjugation computing unit 504, for calculating the conjugated signal of the digital baseband signal that analog to digital converter 503 obtains, obtains the first conjugated signal.The digital baseband signal that analog to digital converter obtains can be expressed as: I
k+ jQ
k, calculate its conjugated signal, obtain the first conjugated signal, be expressed as: I
k-jQ
k.It should be noted that, the Algebraic Expression form that above-mentioned representation is complex signal, can also represent above-mentioned complex signal by exponential form, as above-mentioned digital baseband signal is expressed as
the first conjugated signal is expressed as
wherein, A
kthe amplitude of representative digit baseband signal
the phase place of representative digit baseband signal.
The first delay unit 505 is by the first conjugated signal
time delay one is input in the first multiplier 506 digital baseband signal with next bat after clapping
multiply each other, obtain the first baseband signal
expression formula from the first baseband signal, can find out that the digital baseband signal that the conjugated signal time delay of Contemporary Digital baseband signal one is clapped to rear and next bat multiplies each other, be actually the phase place having realized the digital baseband signal of front and back two bats and subtract each other, realized first difference decoding.
The second conjugation computing unit 507 calculates the conjugated signal of the first baseband signal, obtains the second conjugated signal.The second delay unit 508 is input in the second multiplier 509 and multiplies each other with the first baseband signal of next bat after the second current conjugated signal time delay one is clapped, and obtains the second baseband signal.
The phase place of 510 pairs of the second baseband signals of judging module is adjudicated, and the phase information inverse mapping that judgement is obtained is initial data.The initial data that now decision unit obtains is the data of transmitting terminal transmission.Associated description in other embodiment of specific works process REFERENCE TO RELATED of judging module.
The light signal receiving that the embodiment of the present invention provides, due to the digital baseband signal obtaining is carried out to differential decoding twice, therefore not only can eliminate the asynchronous phase fuzzy problem causing of phase place between local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency between local oscillator light and transmitting terminal light carrier, and the light signal receiving that the embodiment of the present invention provides does not need frequency deviation control circuit and phase estimation module, but still can guarantee the receptivity of light signal receiving.
The embodiment of the present invention also provides a kind of receiving system of light signal, the modulated light signal producing for receive the optical signal generation apparatus of structure shown in Fig. 2 at receiving terminal, and this modulated light signal is processed and recovered the data that transmitting terminal transmits, its structure as shown in Figure 6, comprising: frequency mixer 601, detecting module 602, analog to digital converter 603, phase calculation module 604, the first delay unit 605, the first subtracter 606, the second delay unit 607, the second subtracter 608, judging module 609.Wherein, frequency mixer 601, detecting module 602, analog to digital converter 603 are identical respectively with frequency mixer 401, detecting module 402, analog to digital converter 403 in Fig. 4 shown device, repeat no more here.
The phase place of the digital baseband signal that phase calculation module 604 calculating analog to digital converters 603 obtain, obtains phase signal.The first delay unit 605 is input to the subtraction of being mould 2 π in the first subtracter 606 with the phase signal of next bat after current phase signal time delay one is clapped, and obtains the first phase signal.The second delay unit 607 is input to the subtraction of being mould 2 π in the second subtracter 608 with the first phase signal of next bat after the first current phase place signal lag one is clapped, and obtains the second phase signal.609 pairs of the second phase signals of judging module are adjudicated, and obtain initial data.Because the second phase place code book body is exactly phase information, therefore the process that 609 pairs of the second phase signals of judging module are adjudicated, be actually the process of identification phase place, and then the modulation system adopting when generating modulated light signal according to transmitting terminal, the phase place of identification is carried out to inverse mapping, obtain initial data, the initial data that judging module 609 finally obtains is the data of transmitting terminal transmission.
The light signal receiving that the embodiment of the present invention provides, due to the digital baseband signal obtaining is carried out to differential decoding twice, therefore not only can eliminate the asynchronous phase fuzzy problem causing of phase place between local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency between local oscillator light and transmitting terminal light carrier, and the light signal receiving that the embodiment of the present invention provides does not need frequency deviation control circuit and phase estimation module, but still can guarantee the receptivity of light signal receiving.
The embodiment of the present invention also provides a kind of optical transmission system, comprises any light signal receiving in structure shown in the optical signal generation apparatus of structure shown in Fig. 2 and Fig. 4, Fig. 5, Fig. 6.In this optical transmission system, at transmitting terminal, utilize the optical signal device of structure shown in Fig. 2 that the data of needs transmission are carried out to differential coding twice, then by the data after twice differential coding, light carrier is carried out to phase-modulation, obtain modulated light signal, modulated light signal is coupled in optical fiber, to receiving terminal, transmits; At receiving terminal, in Fig. 4, Fig. 5, Fig. 6, the light signal receiving of any one structure receives the modulated light signal transmitting in optical fiber, then modulated light signal is converted into digital baseband signal, then digital baseband signal is carried out to differential decoding twice, obtain the data of transmitting terminal transmission.
The optical transmission system that the embodiment of the present invention provides, carries out differential coding at transmitting terminal twice by the data of needs transmission, and then by the data after twice differential coding, light carrier is carried out to phase-modulation; At receiving terminal, digital baseband signal is carried out to twice differential decoding and recover the data that transmitting terminal transmits, make the light signal receiving of receiving terminal not need frequency deviation control circuit and phase estimation module, but still can be so that whole system keeps a good error performance.
The invention provides a kind of method that produces light signal, by its method flow as shown in Figure 7, comprising:
Step S701: data are carried out to differential coding, obtain differential coding data for the first time.
Step S702: the first differential coding data are carried out to differential coding, obtain the second differential coding data.
Step S703: by the second differential coding data, light carrier is carried out to phase-modulation, obtain modulated light signal.
In the present embodiment, the data of needs transmission are carried out to differential coding twice, then by the data after twice differential coding, go the phase place of modulated optical carrier, the phase information of the modulated light signal finally obtaining is not the data that direct correspondence will be transmitted, but the data that the phase information of modulated light signal obtains after the twice differential decoding data that just correspondence is transmitted, therefore make receiving terminal adopt local oscillator light and modulated light signal to carry out the digital baseband signal obtaining after the processing such as mixing, need to carry out twice differential decoding and just can recover the data that transmitting terminal transmits, the process of twice decoding not only can be eliminated the asynchronous phase fuzzy problem causing of phase place due to local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency due to local oscillator light and transmitting terminal light carrier, make the realization of receiving terminal receiving system simple.
The embodiment of the present invention also provides a kind of method of reseptance of light signal, adopts the modulated light signal that shown in Fig. 7, method produces, and after processing, recover the data of transmitting terminal transmission for receiving, and its method flow schematic diagram as shown in Figure 8, comprising:
Step S801: receive local oscillator light and modulated light signal, and modulated light signal and local oscillator light are carried out to mixing, obtain the light signal after mixing.
Local oscillator is only produced by the local laser of receiving terminal, and modulated light signal is to adopt method shown in Fig. 7 to produce.
Step S802: the light signal after mixing is surveyed, obtained analog baseband signal.
Concrete, the light signal of the method that can adopt balance detection after to mixing surveyed, and obtains respectively two components of analog baseband signal: I signal and Q signal, and analog baseband signal can be expressed as: I+jQ.
Step S803: analog baseband signal is carried out to analog-to-digital conversion, obtain digital baseband signal.
The I signal of the analog baseband signal that previous step is obtained and Q signal convert respectively digital signal to, obtain two component: I of digital baseband signal
ksignal and Q
ksignal, digital baseband signal can be expressed as: I
k+ jQ
k.
Step S804: the phase place to digital baseband signal is adjudicated, and the phase information inverse mapping that judgement is obtained is Bit data.
Because local oscillator light frequency, phase place are difficult to frequency, the Phase synchronization with the light carrier of transmitting terminal, causing the phase place of the digital baseband signal that obtains is not to concentrate in main value phase place, but be dispersed near main value phase place, when the phase place of digital baseband signal is adjudicated, by its phase place judgement, be immediate main value phase place.For example: modulated light signal is to adopt QPSK modulation to generate, four kinds of phase places utilizing are respectively: π/4,3 π/4,5 π/4,7 π/4, and the phase place of the digital baseband signal in a certain moment obtaining at receiving terminal is 47 °, and the above-mentioned four kinds of main value phase places of this phase value are compared, π/4th, its immediate main value phase place, the phase place judgement of digital baseband signal that should be is constantly π/4.Then the modulation system adopting according to transmitting terminal, by phase information inverse mapping obtained above, it is Bit data, the modulation system adopting as transmitting terminal is QPSK modulation system, the mapping relations of its utilization are: set of signals 00,01,10,11} is mapped as phase sets { π/4,3 π/4,5 π/4,7 π/4}, according to this mapping relations of QPSK modulation system, the phase information that judgement is obtained is carried out inverse mapping, as being Bit data 00 by phase place π/4 inverse mapping of above-mentioned judgement.
Step S805: Bit data is carried out to differential decoding, obtain the first decoded data.
Step S806: the first decoded data is carried out to differential decoding, obtain initial data.Initial data in the present embodiment refers to the data of transmitting terminal transmission.
The process of the differential decoding in step S805 and step S806, the associated description of other embodiment of REFERENCE TO RELATED, repeats no more here.
The light signal method of reseptance that the embodiment of the present invention provides, due to the digital baseband signal obtaining is carried out to differential decoding twice, therefore not only can eliminate the asynchronous phase fuzzy problem causing of phase place between local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency between local oscillator light and transmitting terminal light carrier, and the light signal method of reseptance that the embodiment of the present invention provides does not need local oscillator light to carry out frequency deviation control and phase estimation, but still can guarantee that the data that finally recover have the lower error rate.
The embodiment of the present invention also provides a kind of method of reseptance of light signal, adopts the modulated light signal that shown in Fig. 7, method produces, and after processing, recover the data of transmitting terminal transmission for receiving, and its method flow schematic diagram as shown in Figure 9.Wherein, step S901, S902, S903 are identical respectively with step S801, S802, S803 in method shown in Fig. 8, are no longer described in detail here.
Step S904: the digital baseband signal that the conjugated signal time delay of Contemporary Digital baseband signal one is clapped to rear and next bat multiplies each other, and obtains the first baseband signal.
In this step, the digital baseband signal that the conjugated signal time delay of Contemporary Digital baseband signal one is clapped to rear and next bat multiplies each other, in fact be equivalent to the phase place of the digital baseband signal of front and back two bats (or former and later two constantly) to subtract each other, be also equivalent to realize first difference decoding.It should be noted that, the first baseband signal in this step is still complex signal.
Step S905: the first baseband signal that the conjugated signal time delay of current the first baseband signal one is clapped to rear and next bat multiplies each other, and obtains the second baseband signal.
Step S906: the phase place to the second baseband signal is adjudicated, and the phase information inverse mapping that judgement is obtained is initial data, this initial data is the data of transmitting terminal transmission.Concrete, the phase place of the second baseband signal is adjudicated, obtain phase information, the modulation system of then taking when generating modulated light signal according to transmitting terminal, is Bit data by phase information inverse mapping.What take as transmitting terminal is the phase modulation method of M system, by the phase information inverse mapping of the second baseband signal of each bat, is K Bit data, wherein, and M=2
k(K=1,2,3 ...).
The light signal method of reseptance that the embodiment of the present invention provides, due to the digital baseband signal obtaining is carried out to differential decoding twice, therefore not only can eliminate the asynchronous phase fuzzy problem causing of phase place between local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency between local oscillator light and transmitting terminal light carrier, and the light signal method of reseptance that the embodiment of the present invention provides do not need to local oscillator light carry out that frequency deviation is controlled and and phase estimation, but still can guarantee that the data that finally recover have the lower error rate.
The embodiment of the present invention also provides a kind of method of reseptance of light signal, adopts the modulated light signal that shown in Fig. 7, method produces, and after processing, recover the data of transmitting terminal transmission for receiving, and its method flow schematic diagram as shown in figure 10.Wherein, step S1001, S1002, S1003 are identical respectively with step S801, S802, S803 in method shown in Fig. 8, are no longer described in detail here.
Step S1004: calculate the phase place of digital baseband signal, obtain phase signal.
In this step, concrete can adopt Arg() function calculates the phase place of digital baseband signal, obtains phase signal.
Step S1005: the phase signal that current phase signal time delay one is clapped to rear and next bat is done mould 2 π subtractions, obtains the first phase signal.
The subtraction of mould mould 2 π in this step is similar to the subtraction of mould M, the phase signal that rear and next bat are clapped in current phase signal time delay one subtracts each other, if the result of subtracting each other is not within the scope of 0～2 π, the result of subtracting each other is added or is deducted the value that obtains after n 2 π as the result of mould 2 π subtractions, wherein, the result that the value of n must make to subtract each other adds or deduct the value obtaining after n 2 π must be within 0～2 π; If the result of subtracting each other within the scope of 0～2 π, the result using this result as mould 2 π subtractions.
Step S1006: the phase signal that the phase delay of current first signal one is clapped to rear and next bat is done mould 2 π subtractions, obtains the second phase signal.
Step S1007: the second phase signal is adjudicated, obtain initial data.
The second phase place code book body is exactly phase information, in this step, the second phase signal is adjudicated, be actually the process of identification phase place, and then the modulation system adopting when generating modulated light signal according to transmitting terminal, the phase place of identification is carried out to inverse mapping, obtain initial data.The initial data obtaining in this step is the data of transmitting terminal transmission.
The light signal method of reseptance that the embodiment of the present invention provides, due to the digital baseband signal obtaining is carried out to differential decoding twice, therefore not only can eliminate the asynchronous phase fuzzy problem causing of phase place between local oscillator light and transmitting terminal light carrier, can also further eliminate the asynchronous phase fuzzy problem causing of frequency between local oscillator light and transmitting terminal light carrier, and the light signal method of reseptance that the embodiment of the present invention provides do not need to local oscillator light carry out that frequency deviation is controlled and and phase estimation, but still can guarantee that the data that finally recover have the lower error rate.
The above; be only the present invention's embodiment preferably, but protection scope of the present invention is not limited to this, is anyly familiar with in technical scope that those skilled in the art disclose in the present invention; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claims.
Claims (3)
1. a method of reseptance for light signal, is characterized in that, comprising:
Receive local oscillator light and modulated light signal, and described modulated light signal and local oscillator light are carried out to mixing, obtain the light signal after mixing, wherein, described modulated light signal is that initial data is modulated onto on light carrier resulting through phase-modulation again after twice differential coding;
Light signal after mixing is surveyed, obtained analog baseband signal;
Described analog baseband signal is carried out to analog-to-digital conversion, obtain digital baseband signal;
The digital baseband signal that the conjugated signal time delay of Contemporary Digital baseband signal one is clapped to rear and next bat multiplies each other, and obtains the first baseband signal;
The first baseband signal that the conjugated signal time delay of current the first baseband signal one is clapped to rear and next bat multiplies each other, and obtains the second baseband signal;
Phase place to described the second baseband signal is adjudicated, and the phase information inverse mapping that judgement is obtained is described initial data.
2. a light signal receiving, is characterized in that, comprising:
Frequency mixer, be used for receiving local oscillator light and modulated light signal, and described local oscillator light and described modulated light signal are carried out to mixing, obtain the light signal after mixing, wherein, described modulated light signal is that initial data is modulated onto on light carrier resulting through phase-modulation again after twice differential coding;
Detecting module, for the light signal after described mixing is surveyed, obtains analog baseband signal;
Analog-to-digital conversion module, for described analog baseband signal is carried out to analog-to-digital conversion, obtains digital baseband signal;
The first conjugate module, for calculating the conjugated signal of described digital baseband signal;
The first time delay module, for the conjugated signal time delay of described digital baseband signal one is clapped, obtains the first time delayed signal;
The first multiplier, for the digital baseband signal of described the first time delayed signal and described next bat of digital baseband signal is multiplied each other, obtains the first baseband signal;
The second conjugate module, for calculating the conjugated signal of described the first baseband signal;
The second time delay module, for the conjugated signal time delay of described the first baseband signal one is clapped, obtains the second time delayed signal;
The second multiplier, for the first baseband signal of described the second time delayed signal and described first next bat of baseband signal is multiplied each other, obtains the second baseband signal;
Judging module, for the phase place of described the second baseband signal is adjudicated, and the phase information inverse mapping that judgement is obtained is initial data.
3. an optical transmission system, is characterized in that, comprising:
Optical signal generation apparatus and light signal receiving claimed in claim 2;
Described optical signal generation apparatus comprises:
The first differential coding module, for initial data is carried out to differential coding, obtains the first differential coding data;
The second differential coding module, for described the first differential coding data are carried out to differential coding, obtains the second differential coding;
Modulator, for according to the second differential coding data, light carrier being carried out to phase-modulation, obtains modulated light signal.
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| US8718160B2 (en) | 2011-09-16 | 2014-05-06 | Beijing University Of Posts And Telecommunications | Multi-carrrier optical communication method and system based on DAPSK |
| CN103199940B (en) * | 2012-12-04 | 2016-06-01 | 华中科技大学 | A kind of method of SOQPSK modulation realizing light and system |
| WO2014205737A1 (en) * | 2013-06-27 | 2014-12-31 | 华为技术有限公司 | Signaling processing method and apparatus, and signal receiver |
| BR112016018210B1 (en) | 2014-02-07 | 2023-11-21 | Danmarks Tekniske Universitet | METHOD FOR DECODING A CODED OPTICAL SIGNAL, METHOD FOR TRANSMITTING AN OPTICAL SIGNAL, DETECTOR SYSTEM FOR DECODING A COMBINED AM AND FM CODED OPTICAL SIGNAL, AND OPTICAL COMMUNICATION SYSTEM |
| CN105610517B (en) * | 2014-11-14 | 2018-05-08 | 中兴通讯股份有限公司 | The iteration post-equalization of coherent optical heterodyne communicatio |
| US10142041B2 (en) | 2015-08-11 | 2018-11-27 | Telefonaktiebolaget Lm Ericsson (Publ) | Homodyne receiver calibration |
| CN105680980A (en) * | 2016-02-29 | 2016-06-15 | 成都乐维斯科技有限公司 | Coherent light digital communication method applied to field of optical communication processing |
| CN113810116B (en) | 2017-09-01 | 2023-02-03 | 华为技术有限公司 | Optical signal transmission system and optical signal transmission method |
| EP3866425B1 (en) * | 2018-11-29 | 2023-04-12 | Nippon Telegraph And Telephone Corporation | Reception device, reception method, and program |
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