WO2015192601A1 - 光信号探测与解调装置及*** - Google Patents

光信号探测与解调装置及*** Download PDF

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Publication number
WO2015192601A1
WO2015192601A1 PCT/CN2014/092186 CN2014092186W WO2015192601A1 WO 2015192601 A1 WO2015192601 A1 WO 2015192601A1 CN 2014092186 W CN2014092186 W CN 2014092186W WO 2015192601 A1 WO2015192601 A1 WO 2015192601A1
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Prior art keywords
signal
polarization
optical
light source
modulator
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PCT/CN2014/092186
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English (en)
French (fr)
Inventor
苏婕
迟楠
黄新刚
陈必多
李明生
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中兴通讯股份有限公司
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Priority to EP14895391.2A priority Critical patent/EP3160062A4/en
Publication of WO2015192601A1 publication Critical patent/WO2015192601A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/66—Non-coherent receivers, e.g. using direct detection

Definitions

  • the present invention relates to the field of communications, and in particular to an optical signal detecting and demodulating apparatus and system.
  • the main technologies currently in diversity technology include space, frequency, time and polarization diversity.
  • the current main technical solutions include (1) maximum merging ratio scheme; (2) equal gain merging scheme; (3) selective merging scheme; and (4) switching merging scheme.
  • the above four merging schemes can obtain a plurality of mutually independent tributary signals at the receiving end of the system based on the diversity technique, and obtain the diversity gain through the corresponding merging algorithm, thereby realizing the improvement of the BER performance of the single receiving signal.
  • the maximum combining ratio scheme only needs to linearly process the received signal at the receiving end, and thus has the remarkable feature that the algorithm process is simple and easy to implement.
  • the ONU (Optical Network Unit) signal recovery technology for the Ultra-Dense WDM-PON is generally through direct detection or coherent detection.
  • the technical implementation, but directly detecting the shortcomings of poor performance of the received signal error rate and the coherent detection have the disadvantages of high cost and complicated system structure, therefore, there are certain limitations in practical applications.
  • the present invention provides an optical signal detection method for how to introduce polarization diversity and combining techniques into an ultra-dense WDM-PON system, and has a simple system structure, low cost, and can directly improve the performance of the received signal error rate. Demodulation devices and systems to solve at least the above problems.
  • an optical signal detecting and demodulating apparatus comprising: a tunable optical filter, a polarizing beam splitter, a first photodetector, a second photodetector, a maximum combining ratio module, and a demodulation module, wherein the tunable optical filter is configured to filter out a signal of one channel of the WDM-PON multi-channel of the wavelength division multiplexing passive optical network, to obtain a corresponding optical receiving signal of the channel;
  • the beam device is configured to perform polarization diversity on the light receiving signal, and divide the single light receiving signal into an X polarized light signal and a Y polarized light signal, respectively input to the first photodetector and the second photoelectric a controller; the first photodetector configured to convert the input optical signal into a first electrical signal; the second photodetector configured to convert the input optical signal into a second electrical signal;
  • the maximum combining ratio module is configured to perform weight distribution on the first electrical signal and the second electrical
  • the polarization beam splitter performs polarization diversity on the light receiving information in the following manner: the light receiving signal is divided into two mutually independent copies by a polarization diversity technique, wherein one copy is the X polarization The optical signal, the other copy is the Y-polarized light signal.
  • the maximum combining ratio module includes: an estimating module configured to perform channel estimation on the first electrical signal and the second electrical signal, respectively, to obtain a signal to noise ratio of the first electrical signal, and the a signal to noise ratio of the second electrical signal; the determining module configured to determine a weight assigned to the first electrical signal and the weight according to a signal to noise ratio of the first electrical signal and a signal to noise ratio of the second electrical signal a weight of the second electrical signal, wherein the higher the signal to noise ratio, the greater the weight of the allocation; the summation module is configured to set the weight according to the weight of the first electrical signal and the weight of the second electrical signal to the An electrical signal and the second electrical signal are weighted and summed to be combined into the weighted combined output signal.
  • an optical signal receiving apparatus comprising the above optical signal detecting and demodulating apparatus.
  • an ultra-dense wavelength division multiplexing passive optical network WDM-PON system comprising: the above optical signal receiving device, and light connected to the optical signal receiving device through an optical fiber Signal transmitting equipment.
  • the optical signal transmitting device includes: an orthogonal multi-carrier light source and a Polarization Division Multiplexing-Quadrature Phase Shift Keying (Polyization Division Multiplexing-Quadrature Phase Shift Keying) PDM-QPSK) Optical signal transmission module.
  • an orthogonal multi-carrier light source and a Polarization Division Multiplexing-Quadrature Phase Shift Keying (Polyization Division Multiplexing-Quadrature Phase Shift Keying) PDM-QPSK)
  • PDM-QPSK Polarization Division Multiplexing-Quadrature Phase Shift Keying
  • the orthogonal multi-carrier light source comprises: an external cavity laser, a radio frequency signal source, a DC signal source, two cascaded phase modulators, and an intensity modulator; wherein the external cavity laser is set to be a first one of the two phase modulators of the cascade provides an optical carrier signal; the RF signal source is configured to drive the two cascaded phase modulators and one of the intensity modulators to generate a multi-carrier light source having a uniform and flat frequency of the RF signal; the cascaded phase modulator is configured to generate a multi-carrier light source driven by the RF signal source; the intensity modulator is configured to generate the phase modulator The multi-carrier light source is planarized; the DC signal source is configured to provide a DC bias to the intensity modulator.
  • the intensity modulator planarizes the multi-carrier by planarizing a multi-carrier generated by the companion modulator by adjusting the DC offset and a radio frequency modulation coefficient of the intensity modulator deal with.
  • the ultra-dense PDM-QPSK optical signal transmitting module comprises: an optical add/drop multiplexer, a first polarization controller, a second polarization controller, a first electrical dual channel waveform generator, and a second electrical a dual channel waveform generator, a first in-phase quadrature (IQ) modulator, a second IQ modulator, a first polarization multiplexer, a second polarization multiplexer, and a wavelength selective switch;
  • the optical add/drop multiplexer is configured to divide the multi-carrier outputted by the orthogonal multi-carrier light source into an odd-numbered road light source and an even-numbered road light source, and input an odd-numbered road light source into the first polarization controller to connect an even number of paths
  • the light source is input to the second polarization controller;
  • the first polarization controller is configured to perform polarization control on the input odd-numbered light source, and output the polarization-maintained odd-channel light source to the first IQ modulator;
  • the performance of the bit error rate of the single receiving signal is improved by the polarization diversity technique and the maximum combining ratio algorithm, and the complicated structure of the system of the ordinary space, frequency and time diversity technology is overcome, and the structure of the ONU end of the system is further simplified. To achieve cost control.
  • FIG. 1 is a schematic structural diagram of an ultra-dense WDM-PON system according to an embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of an optical signal detecting and demodulating apparatus according to an embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of an optical signal transmitting apparatus according to an embodiment of the present invention.
  • FIG. 4 is a schematic structural diagram of an orthogonal multi-carrier light source according to an embodiment of the present invention.
  • FIG. 5 is a schematic structural diagram of an ultra-dense PDM-QPSK optical signal transmitting module according to an embodiment of the present invention.
  • the purpose of the embodiments of the present invention is to provide a signal detection and demodulation device (or module) based on a polarization diversity and maximum ratio combining (MRC) algorithm on an ONU end of an ultra-dense WDM-PON system, and keep the system structure as simple and low as possible. Under the premise of cost, the BER performance of the received signal of the system is improved by the maximum merging ratio algorithm.
  • MRC maximum ratio combining
  • an ultra-dense WDM-PON system is provided.
  • FIG. 1 is a schematic structural diagram of a WDM-PON system according to an embodiment of the present invention. As shown in FIG. 1, the system includes: an optical signal receiving device 2 and an optical signal transmitting device 4, wherein the optical signal receiving device 2 and the optical signal transmitting device 4 Connected by fiber 6 between.
  • the optical signal receiving device 2 may be an optical line terminal (OLT), and the optical signal transmitting device 4 may be an optical network unit (ONU).
  • OLT optical line terminal
  • ONU optical network unit
  • the optical signal receiving apparatus 2 includes an optical signal detecting and demodulating device (also referred to as an optical signal control demodulating module) 20, and is configured to detect the received optical signal. With demodulation.
  • the optical signal transmitting apparatus 4 includes an orthogonal multi-carrier light source 40 and an ultra-dense PDM-QPSK optical signal transmitting module 42. Do not describe each module below.
  • the optical signal detecting and demodulating apparatus 20 may include: a tunable optical filter ( Tunable Optical Filter (hereinafter referred to as TOF) 210, Polarizing Beam Splitter (hereinafter referred to as PBS) 220, Optoelectronic Detector (hereinafter referred to as PD) 230, and Second Photodetector (PD) 240 and Maximum merge ratio module 250 and demodulation module 260.
  • TOF tunable Optical Filter
  • PBS Polarizing Beam Splitter
  • PD Optoelectronic Detector
  • PD Second Photodetector
  • the tunable optical filter 210 is configured to filter out an optical signal of a certain channel of the WDM-PON multiple channel (that is, an optical signal sent from the optical signal transmitting device 4) to obtain a corresponding optical receiving signal of the channel.
  • the polarization beam splitter 220 is configured to perform polarization diversity on the light receiving signal, thereby dividing the single signal into two signals of X polarization and Y polarization, and the signals of the two polarization directions are respectively input to the first photodetector (PD) 230 and a second photodetector (PD) 240.
  • a first photodetector (PD) 230 and a second photodetector (PD) 240 are arranged to convert the input optical signal into an electrical signal; a maximum combining ratio module 250 is provided for the first photodetector (PD) 230 and The two electrical signals output by the two photodetectors 240 are weighted to obtain the light receiving The weighted combined output of the signal.
  • the demodulation module 260 is configured to demodulate the weighted combined output signal according to a modulation format adopted by the system transmitting end (ie, the optical signal transmitting device 4), and output the demodulated received signal.
  • the polarization beam splitter 220 may divide the received same optical signal from the optical signal transmitting device into two mutually independent copies by using a polarization diversity technique, and each copy corresponds to one A polarized light signal in the direction of polarization.
  • the polarized light signals in two directions ie, the X-polarized light signal and the Y-polarized light signal
  • the polarized light signals in two directions are obtained by means of a replica, and have a system similar to common diversity techniques such as spatial diversity and time diversity.
  • the maximum merge ratio module 250 may include: an estimation module configured to perform channel estimation on two electrical signals output by the first photodetector (PD) 230 and the second photodetector 240, respectively, to obtain two paths.
  • the signal to noise ratio of the electrical signal PD
  • the determining module is configured to determine the weight assigned to each electrical signal according to the signal to noise ratio of each electrical signal, wherein the higher the signal to noise ratio, the greater the weight assigned;
  • the summation module setting In order to weight the two electrical signals according to the weight of each electrical signal, the combined weighted combined output signals are combined.
  • the maximum merge ratio module 250 first performs channel estimation on the two mutually independent replicas received and determines the weight assigned to the replica according to the signal to noise ratio of the received signal.
  • the channel estimation determines that the signal to noise ratio of the received signal can be obtained by using ON-Off Keying (OOK) at the transmitting end, transmitting the training sequence, and calculating the ratio of the effective signal to the noise at the receiving end. Then, the two independent copies are weighted and summed according to the weights, combined into one output signal to obtain a diversity gain, and the bit error rate performance of the received signal is further improved on the basis of single channel reception.
  • OOK ON-Off Keying
  • the maximum merge ratio module 250 in this alternative embodiment is applicable to any modulation scheme, any branch fading distribution.
  • FIG. 3 is a schematic structural diagram of an optical signal transmitting apparatus according to an embodiment of the present invention.
  • the apparatus mainly includes an orthogonal multi-carrier light source 40 and an ultra-dense PDM-QPSK optical signal transmitting module 42.
  • the orthogonal multi-carrier light source 40 is configured to generate a flat multi-carrier
  • the ultra-dense PDM-QPSK optical signal transmitting module 42 is configured to process the multi-carrier input by the orthogonal multi-carrier light source 40 to generate and transmit an ultra-dense PDM-QPSK.
  • Optical signal Optical signal.
  • the orthogonal multi-carrier light source 40 includes an external cavity laser (ECL) 401 and a radio frequency signal.
  • ECL external cavity laser
  • PM phase modulators
  • the external cavity laser (ECL) 401 is configured to provide an optical carrier signal for a first one of the two phase modulators that are cascaded;
  • the RF signal source 402 is configured to drive two cascaded a phase modulator 404 and one of the intensity modulators 405, generating a multi-carrier light source that is consistent with the RF signal frequency spacing and flat;
  • two of the cascaded phase modulators 404 are arranged to be driven by the RF signal source Generating multiple carriers a light source;
  • the intensity modulator 405 is arranged to planarize a multi-carrier light source produced by the phase modulator;
  • the direct current signal source 403 is arranged to provide a DC bias to the intensity modulator 405.
  • the intensity modulator 405 planarizes the multi-carrier by flattening the multi-carrier generated by the companion modulator 404 by adjusting the DC offset and the RF modulation coefficient of the intensity modulator. deal with.
  • the radio frequency signal source 402 simultaneously drives the two cascaded phase modulators 404 and one of the intensity modulators 405 to generate a frequency interval consistent with the radio frequency signal.
  • Multi-carrier light source wherein the cascaded two phase modulators 404 are primarily used to generate multiple carriers, and the intensity modulator 405 is used to flatten them.
  • the number of multi-carrier sidebands generated by the phase modulator 404 is related to the modulation factor of the phase modulator (the ratio of the input RF driving voltage to the half-wave voltage), and thus, on the one hand, the amplitude value of the input RF signal can be adjusted, and the other Aspects can increase the modulation factor of the phase modulator by employing the two phase modulator cascades, thereby producing a sufficient number of orthogonal photo subcarriers.
  • the DC signal source 403 is primarily used to provide a DC bias to the intensity modulator 405.
  • the photon carrier flattening process can be achieved by adjusting the DC bias of the DC signal source 403 and the RF modulation factor of the intensity modulator 405.
  • FIG. 5 is a schematic structural diagram of an ultra-dense PDM-QPSK optical signal transmitting module according to an embodiment of the present invention.
  • the ultra-dense PDM-QPSK optical signal transmitting module 42 mainly includes: an optical add/drop multiplexer (Inter Leaver (hereinafter referred to as IL) 421, a first polarization controller (Polarization Controller, hereinafter referred to as PC) 422, a second polarization controller 423, a first electric two-channel waveform generator 424, and a second electric two-channel waveform generator 430, a first IQ modulator 425, a second IQ modulator 426, a first polarization multiplexer (Polar-MUX) 427, a second polarization multiplexer 428, and a wavelength selective switch 429.
  • IL optical add/drop multiplexer
  • PC Polarization Controller
  • the optical add/drop multiplexer 421 is configured to divide the multi-carrier outputted by the orthogonal multi-carrier light source into an odd-numbered road light source and an even-numbered road light source, and input an odd-numbered road light source into the first polarization controller 422.
  • the first polarization controller 422 is configured to perform polarization control on the input odd-numbered light sources, and output the polarization-maintained odd-numbered light sources to the first IQ modulator 425;
  • the second vibration controller 423 is configured to perform polarization control on the input even-numbered light source, and output a polarization-maintained even-path light source to the second IQ modulator 426;
  • the first IQ modulator 425 is set to be external The modulation mode modulates the input polarization-maintained odd-path light source to generate a first QPSK signal;
  • the second IQ modulator 426 is configured to modulate the input polarization-maintained even-path light source by external modulation to generate a second QPSK signal;
  • the first electrical dual channel waveform generator 424 configured to generate an electrical signal that drives the first IQ modulator 425;
  • the second electrical dual channel waveform generator 430 Arranging to generate an electrical signal that drives the second IQ modulator 426;
  • the orthogonal multi-carrier light source multi-carrier light source is a comb spectrum light source.
  • the comb-like spectral light source is divided into upper and lower parity by a 1:1 optical add/drop multiplexer, and the odd-numbered roads (1, 3, .. 9, 11) and the even-numbered roads (2, 4, respectively) ..., 10)
  • the wavelength passes through one of the polarization controllers to output an odd-numbered path and an even-numbered path light wave.
  • the polarization-maintained odd-numbered and even-path optical waves independently generate QPSK signals via one of the IQ modulators by external modulation.
  • the two electrical signals that drive the two upper and lower IQ modulators are each generated by one of the electrical two-channel waveform generators.
  • the upper and lower parity QPSK signals respectively generate a PDM-QPSK signal through one of the polarization multiplexers.
  • the WSS described by a two-input port is used to optically filter the odd and even channels respectively to generate an ultra-dense PDM-QPSK signal formed by Quadrature Binary (QDB) spectrum. Since the spacing between the odd and even channels is sufficiently wide, there is basically no crosstalk between channels, which can be regarded as an independent channel. Such filtering is actually equivalent to the effect of the respective filtering of each channel.
  • QDB Quadrature Binary
  • the ultra-dense PDM-QPSK optical signal output by the ultra-dense PDM-QPSK optical signal transmitting module 42 is transmitted to the optical signal detecting and demodulating module via the optical fiber 3, wherein the optical fiber can be used by a standard single mode fiber-28 (SMF) -28) Composition.
  • SMF single mode fiber-28
  • the embodiment of the present invention provides a signal detection and demodulation module based on a polarization diversity and maximum combining ratio algorithm, and applies the signal detection and demodulation module to an ONU end of an ultra-dense WDM-PON system.
  • the signal detecting and demodulating module not only further improves the bit error rate performance of the single receiving signal through the polarization diversity technique and the maximum combining ratio algorithm, but also overcomes the complexity of the system structure of the common space, frequency and time diversity technology, so that The structure of the system ONU is further simplified to achieve cost control.
  • the signal detecting and demodulating module of the embodiment has the characteristics of being suitable for any modulation mode and arbitrary branch fading distribution, and thus has broad application prospects in practical systems.
  • the embodiment of the invention further provides an ultra-dense WDM-PON system based on a signal detection and demodulation module based on polarization diversity and maximum combining ratio algorithm, and the system transmitting end adopts orthogonal multi-carrier based on phase modulator and intensity modulator cascade.
  • the light source generates orthogonal multi-carrier
  • the ultra-dense PDM-QPSK optical signal generation module is used to generate the ultra-dense PDM-QPSK modulated signal
  • the receiving end uses the signal detection and demodulation module based on the polarization diversity and maximum combining ratio algorithm to realize data recovery.
  • the orthogonal multi-carrier light source may include: an external cavity laser, a sinusoidal RF signal source. , phase modulator, electrical amplifier, phase shifter, intensity modulator, and DC signal source.
  • the sinusoidal radio frequency signal source generates a radio frequency signal, wherein one radio frequency signal drives the first one of the phase modulators through one of the electric amplifiers; and the other two radio frequency signals respectively pass one of the phase shifts
  • one of the electrical amplifiers sequentially drives the second of the phase modulator and the intensity modulator.
  • the intensity modulator employs a Mach-Zehnder modulator.
  • the phase shifter is mainly used to adjust the phase mismatch of the input RF signals of different branches.
  • the function of the electrical amplifier is to adjust the amplitude of the RF drive voltage driving the phase modulator and the intensity modulator.
  • the optical signal output by the external cavity laser is input to the first phase modulator for optical modulation, and the output of the first phase modulator is as shown in the formula (1), and V ⁇ is the phase modulator.
  • V rf is the RF drive voltage
  • E in is the incident electric field strength
  • E out is the output electric field strength
  • f s is the sinusoidal RF signal frequency.
  • the output of the first phase modulator is again input as an input signal to the second of the phase modulators, forming a cascade of two phase modulators.
  • the output of the second phase modulator is as shown in equation (2).
  • E out (t) E in (t)exp( ⁇ R 1 sin(2 ⁇ f s t))exp(2 ⁇ R 2 sin(2 ⁇ f s t))
  • the effect of the cascade of the two phase modulators can be considered as a single phase modulator, but the phase modulation factor is increased, solving the problem that the amplitude of a single RF input is not large enough.
  • the modulation factor R1 or R2 is proportional to the radio frequency drive voltage Vrf , preferably by means of which the amplitude of the radio frequency drive voltage driving the two cascaded phase modulators is driven to produce more Light sideband.
  • the frequency spacing between each sideband of the multi-carrier light source is consistent with the signal frequency of the orthogonal radio frequency signal source.
  • the intensity modulator provides a DC bias using one of the DC signal sources.
  • a flat photonic carrier is generated by adjusting the DC bias and the RF modulation factor of the intensity modulator.
  • the ultra-dense PDM-QPSK optical signal transmission module mainly includes: an orthogonal multi-carrier light source, Optical add/drop multiplexer, polarization controller, electrical dual channel waveform generator, IQ modulator, polarization multiplexer, and wavelength selective switch.
  • the optical add/drop multiplexer is divided into two parts by orthogonal multi-carrier input, and the frequency interval between the odd or even path wavelengths is thereby increased to twice the frequency of the radio frequency driving signal.
  • the odd and even path wavelengths are passed through one of the polarization controllers to output polarization-controlled odd and even path wavelengths.
  • the odd-numbered and even-path wavelengths of the polarization-maintained QPSK signals are independently generated by one of the IQ modulators by external modulation.
  • the upper and lower parity QPSK signals respectively generate a PDM-QPSK signal through one of the polarization multiplexers.
  • the WSS of the two input ports is used to optically filter the odd and even channels respectively to generate a QDB spectrum shaped ultra-dense PDM-QPSK signal. Since the spacing between the odd and even channels is sufficiently wide, there is basically no crosstalk between channels, which can be regarded as an independent channel. Such filtering is actually equivalent to the effect of the respective filtering of each channel.
  • This embodiment is an implementation manner of the signal detection and demodulation module based on the polarization diversity and maximum combining ratio algorithm shown in FIG. 2.
  • the signal detection and demodulation module mainly includes: tunable light. Filter, polarization beam splitter, photodetector, maximum combining ratio module and demodulation module.
  • the ultra-dense PDM-QPSK optical signal is transmitted via the standard single-mode fiber-28 as the received signal light input to the signal detection and demodulation module based on the polarization diversity and maximum combining ratio algorithm.
  • the light receiving signal is subjected to polarization diversity by the polarization beam splitter, thereby dividing the single optical signal into two X-polarized and Y-polarized optical signals.
  • the two optical signals of different polarization directions respectively convert the optical signal into an electrical signal through one of the photodetectors.
  • the maximum combining ratio module performs weight distribution for the two input electrical signals, obtains a weighted combined output of the optical receiving signals to obtain a diversity gain, and further improves the bit error rate performance of the received signal based on the single receiving.
  • the weight distribution process mainly performs channel estimation on two independent receiving signals, and assigns a high weight to a branch with a high signal to noise ratio according to a signal to noise ratio of the received signal, and assigns a low weight to a branch with a low signal to noise ratio.
  • the determining the signal to noise ratio of the received signal by channel estimation can be obtained by using the on-off keying modulation (OOK) at the transmitting end, transmitting the training sequence, and calculating the ratio of the effective signal to the noise at the receiving end.
  • OOK on-off keying modulation
  • the demodulation module demodulates the weighted combined output signal according to a modulation format adopted by the system transmitting end, and outputs the demodulated received signal.
  • This embodiment is an implementation manner of the ultra-dense WDM-PON system of the signal detection and demodulation module based on the polarization diversity and maximum combining ratio algorithm shown in FIG. 1.
  • the ultra-dense WDM-PON downlink signal of this embodiment is used.
  • the direction includes: sequential connected orthogonal multi-carrier light source, ultra-dense PDM-QPSK optical signal transmitting module, optical fiber link and signal detection and demodulation module based on polarization diversity and maximum combining ratio algorithm.
  • the orthogonal multi-carrier light source, the ultra-dense PDM-QPSK optical signal transmitting module, and the signal detecting and demodulating module based on the polarization diversity and maximum combining ratio algorithm in this embodiment may adopt the implementations of the first, second and third embodiments respectively
  • the uplink signal direction of the ultra-dense WDM-PON system can be exactly the same as that of the ordinary WDM-PON system, and the uplink modulated optical signal will be generated by the amplitude modulation at the ONU end, and the direct detection is implemented at the OLT end. Detection and demodulation of uplink signals.
  • the maximum combining ratio module in the third embodiment can be implemented by using the corresponding experimental equipment, or can be implemented in the form of a software function module.
  • the embodiment of the present invention provides a novel signal detection and demodulation module based on polarization diversity and maximum combining ratio algorithm, and the signal detection and The demodulation module is applied to the ONU end of an ultra-dense WDM-PON system.
  • the novel signal detection and demodulation module not only achieves further improvement of the bit error rate performance of the single receiving signal through the polarization diversity technique and the maximum combining ratio algorithm, but also overcomes the complexity of the system structure of the common space, frequency and time diversity technology, The structure of the system ONU is further simplified to achieve cost control.
  • the signal detecting and demodulating module proposed by the present invention further It has the characteristics of any modulation mode and arbitrary branch fading distribution, and thus has broad application prospects in practical systems.
  • modules or steps of the present invention described above can be implemented by a general-purpose computing device that can be centralized on a single computing device or distributed across a network of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein.
  • the steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps thereof are fabricated as a single integrated circuit module.
  • the invention is not limited to any specific combination of hardware and software.
  • the performance of the bit error rate of the single receiving signal is improved by the polarization diversity technique and the maximum combining ratio algorithm, and the system complexity of the conventional space, frequency and time diversity technology is overcome, and the system is made.
  • the structure of the ONU side is further simplified to achieve cost control.

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Abstract

本发明公开了一种光信号探测与解调装置及***。该装置包括：可调谐光滤波器、偏振分束器、第一光电探测器、第二光电探测器、最大合并比模块和解调模块，可调谐光滤波器设置为滤出WDM-PON多信道中的一信道的信号，得到该信道的光接收信号；偏振分束器设置为对光接收信号进行偏振分集，将单路光接收信号分为X偏振光信号和Y偏振光信号；第一光电探测器设置为将X偏振光信号转换为第一电信号；第二光电探测器设置为将Y偏振光信号转换为第二电信号；最大合并比模块，设置为将第一电信号和第二电信号进行权重分配，得到光接收信号的加权合并输出信号；解调模块设置为根据***发射端采用的调制格式对加权合并输出信号进行解调，输出解调后的接收信号。

Description

光信号探测与解调装置及*** 技术领域
本发明涉及通信领域，具体而言，涉及一种光信号探测与解调装置及***。
背景技术
目前在分集技术方面的主要技术包括空间、频率、时间和极化分集四类。而在合并技术方面，目前主要技术方案包括(1)最大合并比方案；(2)等增益合并方案；(3)选择式合并方案；(4)切换合并方案等。上述四种合并方案均能基于分集技术在***接收端获得若干相互独立的支路信号，并通过相应的合并算法来获得分集增益，实现对单路接收信号误码率性能的改善。然而，最大合并比方案在接收端只需对接收信号做线性处理，因而具有算法过程简单、易实现的显著特点。另外，针对超密集WDM-PON(Wavelength Division Multiplexing-Passive Optical Network，波分复用无源光网络)的ONU(Optical Network Unit，光网络单元)端信号恢复技术一般通过直接探测或相干探测两类技术实现，但直接探测具有接收信号误码率性能不佳的缺点而相干探测则具有高成本且***结构复杂的不足，因此，在实际应用方面均存在一定局限性。
相关技术中，针对如何将偏振分集与合并技术引入超密集WDM-PON***中，并且***结构简单、成本低且能够对直接探测接收信号误码率性能进行改善的问题，目前尚未提出有效的解决方案。
发明内容
针对如何将偏振分集与合并技术引入超密集WDM-PON***中，并且***结构简单、成本低且能够对直接探测接收信号误码率性能进行改善的问题，本发明提供了一种光信号探测与解调装置及***，以至少解决上述问题。
根据本发明的一个实施例，提供了一种光信号探测与解调装置，包括：可调谐光滤波器、偏振分束器、第一光电探测器、第二光电探测器、最大合并比模块和解调模块，其中，所述可调谐光滤波器设置为滤出波分复用无源光网络WDM-PON多信道中的一信道的信号，得到该信道相应的光接收信号；所述偏振分束器设置为对所述光接收信号进行偏振分集，将单路所述光接收信号分为X偏振光信号和Y偏振光信号，分别输入到所述第一光电探测器和所述第二光电控制器；所述第一光电探测器设置为将输入的光信号转换为第一电信号；所述第二光电探测器设置为将输入的光信号转换为 第二电信号；所述最大合并比模块，设置为将所述第一电信号和所述第二电信号进行权重分配，得到所述光接收信号的加权合并输出信号；所述解调模块设置为根据***发射端采用的调制格式对所述加权合并输出信号进行解调，输出解调后的接收信号。
可选地，所述偏振分束器按照以下方式对所述光接收信息进行偏振分集：通过偏振分集技术将所述光接收信号分为两个相互独立的副本，其中一个副本为所述X偏振光信号，另一个副本为所述Y偏振光信号。
可选地，所述最大合并比模块包括：估计模块，设置为分别对所述第一电信号和所述第二电信号进行信道估计，得到所述第一电信号的信噪比和所述第二电信号的信噪比；确定模块，设置为根据所述第一电信号的信噪比和所述第二电信号的信噪比确定分配给所述第一电信号的权重和所述第二电信号的权重，其中，信噪比越高，分配的权重越大；求和模块，设置为按照所述第一电信号的权重和所述第二电信号的权重，对所述第一电信号和所述第二电信号进行加权求和，合并为所述加权合并输出信号。
根据本发明的另一个实施例，提供了一种光信号接收设备，包括上述光信号探测与解调装置。
根据本发明的又一个实施例，提供了一种超密集波分复用无源光网络WDM-PON***，包括：上述的光信号接收设备，以及通过光纤与所述光信号接收设备连接的光信号发射设备。
可选地，所述光信号发射设备包括：正交多载波光源以及与所述正交多载波光源连接的超密集偏振复用差分相移键控(Polarization Division Multiplexing-Quadrature Phase Shift Keying，简称为PDM-QPSK)光信号发射模块。
可选地，所述正交多载波光源包括：外腔激光器，射频信号源，直流信号源，级联的两个相位调制器，以及强度调制器；其中，所述外腔激光器设置为为所述级联的两个相位调制器中的第一个相位调制器提供光载波信号；所述射频信号源设置为驱动两个级联的所述相位调制器和一个所述强度调制器，产生与射频信号频率间隔一致且平坦的多载波光源；级联的所述相位调制器设置为在所述射频信号源的驱动下产生多载波光源；所述强度调制器设置为将所述相位调制器产生的多载波光源平坦化；所述直流信号源设置为所述强度调制器提供直流偏置。
可选地，所述强度调制器通过以下方式使所述多载波平坦化：通过调节所述直流偏置与所述强度调制器的射频调制系数对所述相伴调制器产生的多载波进行平坦化处理。
可选地，所述超密集PDM-QPSK光信号发射模块包括：光分插复用器、第一偏振控制器、第二偏振控制器、第一电的双信道波形发生器、第二电的双信道波形发生器、第一同相正交(In-phase Quadrature，简称为IQ)调制器、第二IQ调制器、第一偏振复用器、第二偏振复用器和波长选择开关；其中，所述光分插复用器，设置为将所述正交多载波光源输出的多载波分为奇数路光源和偶数路光源，将奇数路光源输入所述第一偏振控制器，将偶数路光源输入第二偏振控制器；所述第一偏振控制器设置为对输入的奇数路光源进行偏振控制，输出偏振保持的奇数路光源至所述第一IQ调制器；所述第二偏振控制器，设置为对输入的偶数路光源进行偏振控制，输出偏振保持的偶数路光源至所述第二IQ调制器；所述第一IQ调制器，设置为采用外调制的方式对输入的偏振保持的奇数路光源进行调制，产生第一QPSK信号；所述第二IQ调制器，设置为采用外调制的方式对输入的偏振保持的偶数路光源进行调制，产生第二QPSK信号；所述第一电的双信道波形发生器，设置为产生驱动所述第一IQ调制器的电信号；所述第二电的双信道波形发生器，设置为产生驱动所述第二IQ调制器的电信号；所述第一偏振复用器，设置为对所述第一QPSK信号进行处理，生成第一PDM-QPSK信号；所述第二偏振复用器，设置为对所述第二QPSK信号进行处理，生成第二PDM-QPSK信号；所述波长选择开关，设置为分别对所述第一PDM-QPSK信号和所述第二PDM-QPSK信号进行光滤波产生经正交二进制频谱成形的超密集PDM-QPSK光信号。
通过本发明，通过偏振分集技术和最大合并比算法实现对单路接收信号误码率性能的进行提升，克服了普通空间、频率及时间分集技术***结构复杂的不足，使得***ONU端的结构进一步简化，实现成本控制。
附图说明
此处所说明的附图用来提供对本发明的进一步理解，构成本申请的一部分，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。在附图中：
图1是根据本发明实施例的超密集波分WDM-PON***的结构示意图；
图2是根据本发明实施例的光信号探测与解调装置的结构示意图；
图3是根据本发明实施例的光信号发射设备的结构示意图；
图4是根据本发明实施例的正交多载波光源的结构示意图；
图5是根据本发明实施例超密集PDM-QPSK光信号发射模块的结构示意图。
具体实施方式
下文中将参考附图并结合实施例来详细说明本发明。需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。
本发明实施例的目的在于在超密集WDM-PON***的ONU端提供基于偏振分集与最大比合并(MRC)算法的信号探测与解调装置(或模块)，在尽可能保持***结构简单、低成本的前提下，通过最大合并比算法提升***接收信号的误码率性能。
根据本发明实施例，提供了一种超密集WDM-PON***。
图1为根据本发明实施例的WDM-PON***的结构示意图，如图1所示，该***包括：光信号接收设备2和光信号发射设备4，其中，光信号接收设备2和光信号发射设备4之间通过光纤6连接。
其中，光信号接收设备2可以是光线路终端(optical line terminal，OLT)，光信号发射设备4可以是光网络单元(Optical Network Unit，ONU)。
如图1所示，在本发明实施例中，光信号接收设备2包括光信号探测与解调装置(也可以称为光信号控制解调模块)20，设置为对接收到的光信号进行探测与解调。光信号发射设备4包括：正交多载波光源40及超密集PDM-QPSK光信号发射模块42。下面别对各个模块进行描述。
图2为根据本发明实施例的光信号探测与解调装置的结构示意图，如图2所示，在本发明实施例中，光信号探测与解调装置20可以包括：可调谐光滤波器(Tunable Optical Filter，以下简称TOF)210、偏振分束器(Polarizing Beam Splitter，以下简称PBS)220、第一光电探测器(Optoelectronic detector,以下简称PD)230、第二光电探测器(PD)240和最大合并比模块250及解调模块260。
其中，所述可调谐光滤波器210设置为滤出WDM-PON多信道中的某一信道的光信号(即从光信号发射设备4发送来的光信号)，得到该信道相应的光接收信号。所述偏振分束器220设置为对所述光接收信号进行偏振分集，从而将单路信号分为X偏振和Y偏振两路信号，所述两个偏振方向的信号分别输入第一光电探测器(PD)230和第二光电探测器(PD)240。第一光电探测器(PD)230和第二光电探测器(PD)240通设置为将输入光信号转换为电信号；最大合并比模块250设置为对第一光电探测器(PD)230和第二光电探测器240输出的两路电信号进行权重分配，得到所述光接收 信号的加权合并输出。所述解调模块260设置为根据***发射端(即光信号发射设备4)采用的调制格式对加权合并输出的信号进行解调，输出解调的接收信号。
可选地，在本发明实施例中，所述偏振分束器220可以通过偏振分集技术将接收的来自光信号发射设备的同一发射光信号分为两个相互独立的副本，每个副本对应一个偏振方向的偏振光信号。采用该可选实施方式，通过副本的方式得到两个方向的偏振光信号(即所述X偏振光信号和所述Y偏振光信号)，相比空间分集、时间分集等常见的分集技术具有***结构简单的优势。
可选地，所述最大合并比模块250可以包括：估计模块，设置为分别对第一光电探测器(PD)230和第二光电探测器240输出的两路电信号进行信道估计，得到两路电信号的信噪比；确定模块，设置为根据各路电信号的信噪比确定分配给各路电信号的权重，其中，信噪比越高，分配的权重越大；求和模块，设置为按照各路电信号的权重，对两路电信号进行加权求和，合并为所述加权合并输出信号。在该可选实施方式中，最大合并比模块250首先分别对接收到的两个相互独立的副本进行信道估计并根据接收信号的信噪比确定分配给该副本的权重，信噪比越高，分配的权重越大。所述信道估计确定接收信号信噪比可通过在发射端采用通断键控调制(ON-Off Keying，以下简称OOK)，发送训练序列，计算接收端的有效信号与噪声的比例来获得。接着对所述两个独立的副本按所述权重进行加权求和，合并为一路输出信号以获得分集增益，在单路接收的基础上进一步改善接收信号的误码率性能。该可选实施方式中的最大合并比模块250适用于任何调制方式、任意支路衰落分布。
图3为根据本发明实施例的光信号发射设备的结构示意图，如图3所示，该设备主要包括正交多载波光源40和超密集PDM-QPSK光信号发射模块42。其中，正交多载波光源40设置为产生平坦的多载波，超密集PDM-QPSK光信号发射模块42设置为对正交多载波光源40输入的多载波进行处理，生成并发射超密集PDM-QPSK光信号。
图4为根据本发明实施例的正交多载波光源的结构示意图，如图4所示，所述正交多载波光源40包括：外腔激光器(External Cavity Laser，以下简称ECL)401、射频信号源402、直流信号源403、以及级联的两个相位调制器(Phase Modulator，以下简称PM)404、和强度调制器405。
其中，所述外腔激光器(ECL)401设置为为级联的两个相位调制器中的第一个相位调制器提供光载波信号；所述射频信号源402设置为驱动两个级联的所述相位调制器404和一个所述强度调制器405，产生与射频信号频率间隔一致且平坦的多载波光源；级联的两个所述相位调制器404设置为在所述射频信号源的驱动下产生多载波 光源；所述强度调制器405设置为将所述相位调制器产生的多载波光源平坦化；所述直流信号源403设置为为所述强度调制器405提供直流偏置。
可选地，所述强度调制器405通过以下方式使所述多载波：通过调节所述直流偏置与所述强度调制器的射频调制系数对所述相伴调制器404产生的多载波进行平坦化处理。
在本发明实施例的可选实施方式中，所述射频信号源402同时驱动所述两个级联的相位调制器404和一个所述强度调制器405，产生与射频信号频率间隔一致且平坦的多载波光源。其中所述级联的两个相位调制器404主要用于产生多载波，而所述强度调制器405则用于使之平坦化。相位调制器404产生的多载波边带数与所述相位调制器的调制系数(输入射频驱动电压与半波电压的比值)有关，因此，一方面可以通过调节输入射频信号的幅度值，另一方面通过采用所述两个相位调制器级联的方式能增大所述相位调制器的调制系数，从而产生数量足够多的正交光子载波。所述直流信号源403主要用于为强度调制器405提供直流偏置。通过调节所述直流信号源403的直流偏置与强度调制器405的射频调制系数能实现对产生光子载波平坦化处理。
图5为根据本发明实施例的超密集PDM-QPSK光信号发射模块的结构示意图，如图5所示，该超密集PDM-QPSK光信号发射模块42主要包括：光分插复用器(Inter Leaver，以下简称IL)421、第一偏振控制器(Polarization Controller，以下简称PC)422、第二偏振控制器423、第一电的双信道波形发生器424、第二电的双信道波形发生器430、第一IQ调制器425、第二IQ调制器426、第一偏振复用器(Polarization Multiplexing,以下简称PoL-MUX)427、第二偏振复用器428和波长选择开关429。
其中，所述光分插复用器421，设置为将所述正交多载波光源输出的多载波分为奇数路光源和偶数路光源，将奇数路光源输入所述第一偏振控制器422，将偶数路光源输入第二偏振控制器423；所述第一偏振控制器422设置为对输入的奇数路光源进行偏振控制，输出偏振保持的奇数路光源至所述第一IQ调制器425；所述第二振控制器423，设置为对输入的偶数路光源进行偏振控制，输出偏振保持的偶数路光源至所述第二IQ调制器426；所述第一IQ调制器425，设置为采用外调制的方式对输入的偏振保持的奇数路光源进行调制，产生第一QPSK信号；所述第二IQ调制器426，设置为采用外调制的方式对输入的偏振保持的偶数路光源进行调制，产生第二QPSK信号；所述第一电的双信道波形发生器424，设置为产生驱动所述第一IQ调制器425的电信号；所述第二电的双信道波形发生器430设置为产生驱动所述第二IQ调制器426的电信号；所述第一偏振复用器427，设置为对所述第一QPSK信号进行处理，生成第一PDM-QPSK信号；所述第二偏振复用器428，设置为对所述第二QPSK信号进行 处理，生成第二PDM-QPSK信号；所述波长选择开关429，设置为分别对所述第一QPSK信号和所述第二QPSK信号进行光滤波产生经正交二进制频谱成形的超密集PDM-QPSK光信号。
在本发明实施例的一个可选实施方式中，所述正交多载波光源多载波光源，即梳状谱光源。所述梳状谱光源经过一个所述1:1的光分插复用器分为上下奇偶两路，分别将奇数路(1,3,..9,11)和偶数路(2,4,…,10)波长经过一个所述偏振控制器输出偏振保持的奇数路和偶数路光波。所述偏振保持的奇数路和偶数路光波分别通过外调制的方式经一个所述IQ调制器独立产生QPSK信号。驱动上下两个所述IQ调制器的两路电信号分别由一个所述电的双信道波形发生器产生。接着上下奇偶两路QPSK信号分别通过一个所述偏振复用器产生PDM-QPSK信号。最后采用一个两输入口所述的WSS对奇数和偶数信道分别进行光滤波产生经正交二进制(Quadrature Binary，以下简称QDB)频谱成形的超密集PDM-QPSK信号。由于奇数和偶数信道的间隔足够宽，因此基本上信道间无串扰，可以视为独立信道。这样滤波实际上等效于每个信道各自滤波的效果。
超密集PDM-QPSK光信号发射模块42输出的所述超密集PDM-QPSK光信号经光纤3传输至所述光信号探测与解调模块，其中所述光纤可以由标准单模光纤-28(SMF-28)组成。
如上所述，本发明实施例提供了一种基于偏振分集与最大合并比算法的信号探测与解调模块，并将该信号探测与解调模块应用于一个超密集WDM-PON***ONU端。所述信号探测与解调模块不仅通过偏振分集技术和最大合并比算法实现对单路接收信号误码率性能的进一步提升，还克服了普通空间、频率及时间分集技术***结构复杂的不足，使得***ONU端的结构进一步简化，实现成本控制。此外本实施例的所述信号探测与解调模块还具有适用于任何调制方式、任意支路衰落分布的特点，因而在实际***的具有广阔的应用前景。
本发明实施例还提供了一个基于偏振分集与最大合并比算法的信号探测与解调模块的超密集WDM-PON***，***发射端采用基于相位调制器与强度调制器级联的正交多载波光源产生正交多载波，采用超密集PDM-QPSK光信号生成模块生成超密集PDM-QPSK调制信号；接收端采用基于偏振分集与最大合并比算法的信号探测与解调模块实现数据恢复。
下面通过具体实施例对本发明实施例提供的技术方案进行说明。
实施例一
本实施例为图4所示的频率锁定且功率平坦的正交多载波光源的一种实施方式，如图4所示，所述正交多载波光源可以包括：外腔激光器、正弦射频信号源、相位调制器、电放大器、相移器、强度调制器以及直流信号源。
在本实施例中，首先，所述正弦射频信号源生成射频信号，其中一路射频信号通过一个所述电放大器驱动第一个所述相位调制器；另两路射频信号分别通过一个所述相移器和一个所述电放大器依次驱动第二个所述相位调制器和所述强度调制器。优选地，所述强度调制器采用马赫曾德尔调制器。所述相移器主要用于调节不同支路输入射频信号的相位失配。所述电放大器的作用是对驱动所述相位调制器与强度调制器的射频驱动电压幅度进行调节。
接着，所述外腔激光器输出的光信号输入第一个所述相位调制器进行光调制，且第一个所述相位调制器的输出如式(1)所示，Vπ为相位调制器的半波电压，Vrf为射频驱动电压，R1＝Vrf/Vπ表示调制系数，Ein为入射电场强度，Eout为输出电场强度,fs为正弦射频信号频率。
Figure PCTCN2014092186-appb-000001
其次第一个所述相位调制器的输出再次作为输入信号输入到第二个所述相位调制器，形成两个相位调制器的级联。第二个所述相位调制器的输出如式(2)所示，
Eout(t)＝Ein(t)exp(πR1sin(2πfst))exp(2πR2sin(2πfst))
＝Ein(t)exp(π(R1+R2)sin(2πfst))
＝Ein(t)exp(πRNsin(2πfst))       (2)
其中RN＝R1+R2，因此两个所述相位调制器级联的效果可以视为单个相位调制器，但是相位调制系数增大了，解决单个射频输入幅度不够大的问题。此外如上所示，调制系数R1或R2与射频驱动电压Vrf成正比，优选地，通过所述电放大器调节驱动所述两个级联的相位调制器的射频驱动电压的幅度从而产生更多的光边带。所述多载波光源各边带间的频率间隔与所述正交射频信号源的信号频率一致。
最后，将所述两个级联的相位调制器中的第二相位调制器输出再输入所述强度调制器实现对产生光子载波的平坦化处理。所述强度调制器采用一个所述直流信号源提供直流偏置。优选地，通过调节所述强度调制器的直流偏置和射频调制系数从而产生平坦的光子载波。
实施例二
本实施例为图5所示的超密集PDM-QPSK光信号发射模块的一种实施方式，如图5所示，所述超密集PDM-QPSK光信号发射模块主要包括：正交多载波光源、光分插复用器、偏振控制器、电的双信道波形发生器、IQ调制器、偏振复用器，以及波长选择开关。
首先由正交多载波输入所述光分插复用器分为奇偶两部分，所述的奇数或偶数路波长间的频率间隔将由此增加到射频驱动信号频率的两倍。
其次所述将奇数和偶数路波长经过一个所述偏振控制器输出偏振保持的奇数路和偶数路波长。
再次所述偏振保持的奇数路和偶数路波长分别通过外调制的方式经一个所述IQ调制器独立产生QPSK信号。通过两个所述电的双信道波形发生器产生两路电信号驱动上下两个所述IQ调制器，
接着上下奇偶两路QPSK信号分别通过一个所述偏振复用器产生PDM-QPSK信号。
最后采用一个所述两输入口的WSS对奇数和偶数信道分别进行光滤波产生QDB频谱成形的超密集PDM-QPSK信号。由于奇数和偶数信道的间隔足够宽，因此基本上信道间无串扰，可以视为独立信道。这样滤波实际上等效于每个信道各自滤波的效果。
实施例三
本实施例为图2所示的基于偏振分集与最大合并比算法的信号探测与解调模块的一种实施方式，如图2所示，所述信号探测与解调模块主要包括：可调谐光滤波器,偏振分束器，光电探测器,最大合并比模块以及解调模块。
首先超密集PDM-QPSK光信号经由标准单模光纤-28传输作为接收信号光输入所述基于偏振分集与最大合并比算法的信号探测与解调模块。
其次，通过所述可调谐光滤波器滤出超密集WDM-PON多信道中的某一信道，得到该信道相应的光接收信号。
再次，通过所述偏振分束器对所述光接收信号进行偏振分集，从而将单路光信号分为X偏振和Y偏振两路光信号。
接着，所述两路不同偏振方向的光信号分别通过一个所述光电探测器将光信号转换为电信号。
随后，所述最大合并比模块将为两路输入电信号进行权重分配，得到所述光接收信号的加权合并输出以获得分集增益，在单路接收的基础上进一步改善接收信号的误码率性能。所述权重分配过程主要通过对两路独立的接收信号进行信道估计，根据接收信号信噪比为信噪比高的支路分配高权重，为信噪比低的支路分配低权重实现。所述通过信道估计确定接收信号信噪比可通过在发射端采用通断键控调制(OOK)，发送训练序列，计算接收端的有效信号与噪声的比例来获得。
最后所述解调模块对所述加权合并输出信号根据***发射端采用的调制格式进行解调，输出解调的接收信号。
实施例四
本实施例为图1所示的基于偏振分集与最大合并比算法的信号探测与解调模块的超密集WDM-PON***的一种实施方式，本实施例的所述超密集WDM-PON下行信号方向包括：顺序连接的正交多载波光源，超密集PDM-QPSK光信号发射模块，光纤链路及基于偏振分集与最大合并比算法的信号探测与解调模块。
本实施例中的正交多载波光源、超密集PDM-QPSK光信号发射模块、及基于偏振分集与最大合并比算法的信号探测与解调模块可以分别采用第一、二、三实施例的实施方式，相关技术细节可以参见上述实施例，为了减少重复，这里不再赘述。需要特别提及的是，对于所述超密集WDM-PON***上行信号方向可以与普通WDM-PON***完全相同，在ONU端将采用幅度调制产生上行发射光信号在OLT端将通过直接探测实现对上行信号的探测与解调。
本领域普通技术人员可以理解上述实施例中的除实施例三中的最大合并比模块外均可采用相应的实验器材实现，也可以采用软件功能模块的形式实现。
从以上的描述中，可以看出，本发明实现了如下技术效果：本发明实施例提供了一种新型的基于偏振分集与最大合并比算法的信号探测与解调模块，并将该信号探测与解调模块应用于一个超密集WDM-PON***ONU端。该新型信号探测与解调模块不仅通过偏振分集技术和最大合并比算法实现对单路接收信号误码率性能的进一步提升，还克服了普通空间，频率，时间分集技术***结构复杂的不足，使得***ONU端的结构进一步简化，实现成本控制。此外本发明提出的所述信号探测与解调模块还 具有适用于任何调制方式、任意支路衰落分布的特点，因而在实际***的具有广阔的应用前景。
显然，本领域的技术人员应该明白，上述的本发明的各模块或各步骤可以用通用的计算装置来实现，它们可以集中在单个的计算装置上，或者分布在多个计算装置所组成的网络上，可选地，它们可以用计算装置可执行的程序代码来实现，从而，可以将它们存储在存储装置中由计算装置来执行，并且在某些情况下，可以以不同于此处的顺序执行所示出或描述的步骤，或者将它们分别制作成各个集成电路模块，或者将它们中的多个模块或步骤制作成单个集成电路模块来实现。这样，本发明不限制于任何特定的硬件和软件结合。
以上所述仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。
工业实用性
基于本发明提供的上述技术方案，通过偏振分集技术和最大合并比算法实现对单路接收信号误码率性能的进行提升，克服了普通空间、频率及时间分集技术***结构复杂的不足，使得***ONU端的结构进一步简化，实现成本控制。

Claims (9)

  1. 一种光信号探测与解调装置，包括：可调谐光滤波器、偏振分束器、第一光电探测器、第二光电探测器、最大合并比模块和解调模块，其中，
    所述可调谐光滤波器设置为滤出波分复用无源光网络WDM-PON多信道中的一信道的信号，得到该信道相应的光接收信号；
    所述偏振分束器设置为对所述光接收信号进行偏振分集，将单路所述光接收信号分为X偏振光信号和Y偏振光信号，分别输入到所述第一光电探测器和所述第二光电控制器；
    所述第一光电探测器设置为将输入的光信号转换为第一电信号；
    所述第二光电探测器设置为将输入的光信号转换为第二电信号；
    所述最大合并比模块，设置为将所述第一电信号和所述第二电信号进行权重分配，得到所述光接收信号的加权合并输出信号；
    所述解调模块设置为根据***发射端采用的调制格式对所述加权合并输出信号进行解调，输出解调后的接收信号。
  2. 根据权利要求1所述的装置，其中，所述偏振分束器按照以下方式对所述光接收信息进行偏振分集：通过偏振分集技术将所述光接收信号分为两个相互独立的副本，其中一个副本为所述X偏振光信号，另一个副本为所述Y偏振光信号。
  3. 根据权利要求1所述的装置，其中，所述最大合并比模块包括：
    估计模块，设置为分别对所述第一电信号和所述第二电信号进行信道估计，得到所述第一电信号的信噪比和所述第二电信号的信噪比；
    确定模块，设置为根据所述第一电信号的信噪比和所述第二电信号的信噪比确定分配给所述第一电信号的权重和所述第二电信号的权重，其中，信噪比越高，分配的权重越大；
    求和模块，设置为按照所述第一电信号的权重和所述第二电信号的权重，对所述第一电信号和所述第二电信号进行加权求和，合并为所述加权合并输出信号。
  4. 一种光信号接收设备，包括权利要求1至3中任一项所述光信号探测与解调装置。
  5. 一种超密集波分复用无源光网络WDM-PON***，包括：权利要求4所述的光信号接收设备，以及通过光纤与所述光信号接收设备连接的光信号发射设备。
  6. 根据权利要求5所述的***，其中，所述光信号发射设备包括：正交多载波光源以及与所述正交多载波光源连接的超密集偏振复用差分相移键控PDM-QPSK光信号发射模块。
  7. 根据权利要求6所述的***，其中，所述正交多载波光源包括：外腔激光器，射频信号源，直流信号源，级联的两个相位调制器，以及强度调制器；
    所述外腔激光器设置为为所述级联的两个相位调制器中的第一个相位调制器提供光载波信号；
    所述射频信号源设置为驱动两个级联的所述相位调制器和一个所述强度调制器，产生与射频信号频率间隔一致且平坦的多载波光源；
    级联的所述相位调制器设置为在所述射频信号源的驱动下产生多载波光源；
    所述强度调制器设置为将所述相位调制器产生的多载波光源平坦化；
    所述直流信号源设置为为所述强度调制器提供直流偏置。
  8. 根据权利要求7所述的***，其中，所述强度调制器通过以下方式使所述多载波平坦化：通过调节所述直流偏置与所述强度调制器的射频调制系数对所述相伴调制器产生的多载波进行平坦化处理。
  9. 根据权利要求6所述的***，其中，所述超密集PDM-QPSK光信号发射模块包括：光分插复用器、第一偏振控制器、第二偏振控制器、第一电的双信道波形发生器、第二电的双信道波形发生器、第一IQ调制器、第二IQ调制器、第一偏振复用器、第二偏振复用器和波长选择开关；其中，
    所述光分插复用器，设置为将所述正交多载波光源输出的多载波分为奇数路光源和偶数路光源，将奇数路光源输入所述第一偏振控制器，将偶数路光源输入第二偏振控制器；
    所述第一偏振控制器，设置为对输入的奇数路光源进行偏振控制，输出偏振保持的奇数路光源至所述第一IQ调制器；
    所述第二偏振控制器，设置为对输入的偶数路光源进行偏振控制，输出偏振保持的偶数路光源至所述第二IQ调制器；
    所述第一IQ调制器，设置为采用外调制的方式对输入的偏振保持的奇数路光源进行调制，产生第一QPSK信号；
    所述第二IQ调制器，设置为采用外调制的方式对输入的偏振保持的偶数路光源进行调制，产生第二QPSK信号；
    所述第一电的双信道波形发生器，设置为产生驱动所述第一IQ调制器的电信号；
    所述第二电的双信道波形发生器，设置为产生驱动所述第二IQ调制器的电信号；
    所述第一偏振复用器，设置为对所述第一QPSK信号进行处理，生成第一PDM-QPSK信号；
    所述第二偏振复用器，设置为对所述第二QPSK信号进行处理，生成第二PDM-QPSK信号；
    所述波长选择开关，设置为分别对所述第一PDM-QPSK信号和所述第二PDM-QPSK信号进行光滤波产生经正交二进制频谱成形的超密集PDM-QPSK光信号。
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