CN101227633A - A device and method for optical label switching based on FSK/ASK quadrature modulation - Google Patents

Abstract

The invention discloses an information processing device, which is mainly used for information generation, transmission and reception of an IP-over-DWDM optical network, wherein the information processing device includes an edge router, a transmission module and a signal receiving part. The edge router realizes effectively carrying marks and loads mainly through a single distributed feedback laser and a Mach-Zehnder modulator. In addition, the invention discloses a corresponding information transmission method. Since the marker signal and the payload signal adopt the FSK/ASK orthogonal joint modulation method, it overcomes the disadvantage that the existing optical switching network can only carry the load signal, and the marker signal containing routing information can only be transmitted in the electrical switching network; at the same time, FSK It uses the same optical wavelength as the ASK signal, which effectively improves the utilization rate of network bandwidth resources.

Description

A device and method for optical label switching based on FSK/ASK quadrature modulation

technical field

The invention relates to the field of optical communication, in particular to a method and device for realizing optical label switching based on FSK/ASK quadrature modulation.

Background technique

With the rapid development of the Internet, the demand for network bandwidth continues to expand. From the perspective of transmission, the current communication network is an optical transmission network, but at the switching level of the communication network, whether it is line switching or packet switching, almost all are based on electrical switching. or routing technology. Due to the speed bottleneck limitation of electronic technology, the rate signal carried by the optical wavelength channel link needs to be rate matched at the switching node. The direct consequence of this is that the switching node becomes the bottleneck of the entire communication network, and a large number of optical/electrical interface adaptation and rate matching operations between the two subnets reduce the utilization of network resources, reduce network performance, and increase network costs. If the electrical switching subnet of the communication network can be transformed into an optical switching subnet, the problems caused by the coexistence of the optical transmission subnet and the electrical switching subnet will be solved, so that the data plane of the entire communication network can be seamlessly realized on the optical plane. Convergence, there is no doubt that the realization of optical switching should be the development trend of communication networks. Similar to the traditional electrical switching technology, the optical switching technology can be roughly divided into two categories: Optical Circuit Switching (OCS, Optical Circuit Switching) and Optical Packet Switching (OPS, Optical Packet Switching) from the switching system. In recent years, people have proposed a new optical switching technology——optical label switching technology. The basic idea is to directly realize the optical packet routing and forwarding functions of Multi-Protocol Labeled Switching (MPLS, Multi-Protocol Labeled Switching) at the optical layer. Although the research in this area has made some progress so far, it is still in the initial research stage, and there are still a lot of problems that have not been resolved, and further research is needed.

Contents of the invention

The technical problem to be solved by the present invention is: to overcome the problems of complex design and operation of the existing optical label switching network, low utilization rate of frequency resources, and relatively difficult implementation, and provide a new method of optical label switching, which makes its structure simple , It is easy to implement and has a high utilization rate of network bandwidth resources.

The optical label switching technical solution adopted in the present invention is:

First, the IP data packet information forms a frequency shift keying/amplitude shift keying (FSK/ASK, Frequency Shift Keying/Amplitude Shift Keying) quadrature joint modulation signal at the edge router:

The header information of the low-speed IP data packet performs direct intensity modulation on a single distributed feedback (DFB, Distributed Feed-back) laser to generate an FSK optical marking signal, and then enters the M-Z modulator.

The payload of the high-speed IP data packet is converted into a signal suitable for optical fiber transmission through relevant coding technology, and then input to the Mach-Zehnder Modulator (MZM, Mach-Zehnder Modulator).

The MZM in the edge router part is used to modulate the IP payload onto the FSK optical marker signal, realize the orthogonal joint modulation of FSK/ASK, and generate the FSK/ASK signal.

Then, the FSK/ASK quadrature signal passes through the transmission part of the system, and generates signal dispersion and introduces various noises:

Erbium Doped Fiber Amplifiers (EDFA, Erbium Doped Fiber Amplifiers), used to increase the FSK/ASK signal transmission power, or to amplify the weakened signal in optical fiber transmission.

Single-mode dispersion fiber (SMF, Single Mode Fiber) and dispersion compensation fiber (DCF, Dispersion Compensation Fiber), while providing long-distance transmission paths for signals, generate positive and negative signal dispersion respectively.

Finally, the transmitted and exchanged signal enters the receiving part of the IP header information (carried by the FSK optical signal) and IP payload (carried by the ASK optical signal) of the system, and the signal is demodulated:

First, the coupler divides the transmitted signal into two parts according to the power ratio, so that they enter the FSK signal receiver and the ASK signal receiver respectively.

Secondly, in the FSK signal receiver part, the signal first passes through a narrow-band optical filter (OBPF, OpticalBandpass Filter), and by selecting an appropriate filter bandwidth, a peak point in the FSK signal is filtered out, leaving another single-frequency signal information; Then through the photoelectric detector, the single-frequency optical signal is converted into an electrical signal, and the small signal is amplified through the preamplifier; finally, the IP header information is demodulated through the filtering and shaping effect of the low-pass filter (LPF, Low PassFilter). come out.

Similarly, in the ASK signal receiver part, the signal signal from the coupler first passes through a narrowband optical filter to filter out the noise introduced by the orthogonal signal in the channel; The ASK signal is converted into an electrical signal, and the small signal is amplified through the preamplifier; finally, the IP payload is demodulated through the filtering and shaping function of the low-pass filter.

The beneficial effect of the present invention is that the FSK and ASK signals are essentially the same optical wavelength signal, so there is no additional frequency resource consumption, and the network bandwidth resource utilization rate is high. In addition, the modulation and demodulation system is simple in structure, easy to implement, and has practical operability.

Description of drawings

FIG. 1 is a structural diagram of an edge router of the present invention. It consists of a signal generator, a DFB tunable laser, an M-Z modulator (MZM), and a Gaussian filter.

Fig. 2 is a schematic diagram of a new optical marking system model based on FSK/ASK quadrature modulation of the present invention. The transmission part is composed of erbium-doped fiber amplifier (EDFA), single-mode fiber (SMF), dispersion compensation fiber (DCF); the receiver part is composed of coupler (Coupler), optical bandpass filter (OBPF), photodetector, Composition of amplifier and low-pass filter (LPF);

Fig. 3 is the spectrum diagram of the FSK light mark signal modulated by the DFB laser among the present invention;

Fig. 4 is the time-domain diagram of the IP packet net load Payload without any modulation among the present invention;

Fig. 5 is the time-domain diagram of the signal after the FSK/ASK quadrature modulation of the Label and Payload signals in the present invention;

Fig. 6 is a spectrum diagram of the signal after passing through the FSK receiver in the present invention.

Fig. 7 is the eye pattern of signal through ASK receiver among the present invention;

Fig. 8 is the eye diagram of signal through FSK receiver in the present invention

Detailed ways

Below according to accompanying drawing and example the present invention will be described in further detail:

The edge router shown in Figure 1 first collects, buffers and forwards error correction (FEC, Forward Error Correction) for the IP data packets from the access network, and then converts the header information (Label) and payload of the IP data packets (Payload) for separation.

The header information Label of the low-speed IP data packet, the present invention takes 155Mb/s as an example, carries out direct intensity modulation to the DFB laser, and determines a wavelength λ ₀ as the operating wavelength of the laser according to the network operation status, and the present invention uses the center frequency point f ₀ Taking 193.10THz as an example, the chirp effect of the laser is used to generate frequency modulation, that is, to generate the FSK optical marking signal FSK Label. This process needs to select an appropriate frequency difference Δf, and the present invention takes the frequency difference Δf as 20 GHz as an example. Figure 3 is its modulation spectrum diagram. The FSK Label then enters the optical signal input end of the MZ modulator.

As for the payload Payload of the high-speed IP data packet, the present invention takes 10Gb/s as an example, and FIG. 4 is a time domain diagram thereof. First, it is converted into a signal format suitable for optical fiber transmission through relevant coding technology, and then input to the arm of the M-Z modulator, that is, the electrical signal control end of the M-Z modulator.

In the MZM part in Figure 1, the payload Payload of the high-speed IP data packet input to the electrical signal control terminal is modulated to the input low-speed FSK optical label signal FSK Label through external modulation technology, and the light intensity is modulated, that is, ASK modulation. In this way, the FSK/ASK quadrature joint modulation of the signal is realized, and the FSK/ASK quadrature signal is generated. Fig. 5 is a time domain diagram of FSK/ASK quadrature modulation. At the same time, the edge router determines the route for the orthogonal joint signal according to the IP header information Label, and transmits it to a suitable core router for switching, and the core router part is omitted here. The extinction ratio of MZM in this part will greatly affect the performance of the system, and it is necessary to select the appropriate extinction ratio of MZM according to the system requirements.

Figure 1 shows the edge router module in Figure 2 . The FSK/ASK quadrature-modulated optical packet marking signal formed here then enters the transmission module as shown in Figure 2, which includes:

Erbium-doped fiber amplifier (EDFA), one of which is located behind the edge router, is used to increase the transmission power of FSK/ASK signals, so that the transmission distance in the optical fiber is long enough; the other is located in the transmission path or in front of the signal receiver, used to enhance The energy attenuated by a signal during optical fiber transmission.

Single-mode dispersion fiber (SMF) is used to provide a long-distance transmission path for the input signal while generating positive dispersion of the signal.

Dispersion Compensating Fiber (DCF), used to provide a long-distance transmission path for the signal, and properly compensate the positive dispersion generated by the signal passing through the SMF. Among them, DCF can be placed before or after SMF or mixed with SMF.

The transmitted and exchanged FSK/ASK orthogonal signal enters the receiving module of IP header information and IP payload as shown in Figure 2:

The coupler is used to divide the transmitted FSK/ASK quadrature signal into two parts according to the power ratio, one part enters the FSK signal receiver, and the other part enters the ASK signal receiver.

The FSK signal receiver is used to receive the signal from the coupler, and separate the optical mark signal part in the orthogonal signal, detect, amplify, filter and judge the FSK signal, and demodulate the mark signal, that is, the part of the IP data packet header information. The signals entering the FSK signal receiver go through:

The narrow-band optical filter (OBPF), selects the appropriate filter bandwidth, and is used to filter out a peak point f ₁ in the FSK signal, leaving the single-frequency f ₂ signal information. Fig. 6 is a spectrum diagram of the signal after passing through the FSK narrow-band optical filter.

The photoelectric detector (PIN) and the preamplifier receive the output of the narrow-band optical filter and directly detect the signal strength of the orthogonal optical signal, that is, convert the FSK signal into an electrical signal, thereby demodulating the IP header information, and then This weak electrical signal is amplified.

The low-pass filter receives the photoelectric detection and the output of the preamplifier, and shapes the header information signal of the IP data packet to reduce the bit error rate of the header information signal.

The ASK signal receiver is used to receive the signal from the coupler, separate the optical payload information part in the orthogonal signal, detect, amplify, filter and judge the ASK signal, and demodulate the payload information. The signals entering the ASK signal receiver go through:

The narrow-band optical filter (OBPF) selects the appropriate filter bandwidth to filter out the noise introduced by the quadrature signal in the channel.

The photoelectric detector (PIN) and the preamplifier receive the output of the narrow-band optical filter and directly detect the signal strength of the orthogonal optical signal, that is, convert the ASK signal into an electrical signal, thereby demodulating the IP payload, and then the This weak electrical signal is amplified.

The low-pass filter receives the photoelectric detection and the output of the preamplifier, and shapes the IP data payload information signal to reduce the bit error rate of the payload information.

In summary, the present invention marks optical information based on FSK/ASK orthogonal modulation, so that FSK and ASK signals belong to the same optical wavelength signal, saving a lot of network frequency resources. The program is more practical and operable.

In a word, the above descriptions are only preferred embodiments of the present invention, and are not only used to limit the protection scope of the present invention. Several equivalent deformations and substitutions can be made, and these equivalent deformations and substitutions should also be regarded as the protection scope of the present invention.

Claims (8)

1. information processing and transmission equipment are used for generation, transmission and the demodulation of FSK/ASK quadrature associating modulated light signal, it is characterized in that, comprising:

Edge router, be used for the IP packet from Access Network compile, buffering and forward error correction, and the header of IP packet separated with net load.The header of the IP packet signal that serves as a mark then it is carried out the FSK modulation, and net load at a high speed carries out the ASK modulation by the control light intensity, realizes the quadrature modulation with header;

Signal transmission line is used to transmit the orthogonal optical signal that described edge router produces;

Signal receiver is used to separate the FSK/ASK orthogonal optical signal that described edge router produces, the signal transmission line transmission comes, and respectively fsk signal and ASK signal is detected, amplifies and adjudicate, and demodulates marking signal and net load;

2. described information processing according to claim 1 and transmission equipment is characterized in that, described edge router comprises:

Signal generator, be used for the IP packet from Access Network compile, buffering and forward error correction, and the header of IP packet separated with net load, produce the label information and the net load at a high speed of relative low speed;

Single distributed feedback laser is used for the low speed marking signal of input is carried out the FSK modulation.The IP header packet information signal that serves as a mark, drive a little bias current and directly modulate single distributed feedback laser, utilize the sign indicating number frequency of two spectral shifts of generation of warbling of laser, and determine the operation wavelength of some wavelength X as laser according to the operating position of network medium wavelength resource;

Mach-Zehnder modulators is used to realize that the quadrature of marking signal and net load unites modulation.The flag F SK signal of modulated low speed enters Mach-Zehnder modulators, and payload signal at a high speed enters the signal of telecommunication control end of Mach-Zehnder modulators, produce the ASK signal by intensity modulated, realize that the quadrature of FSK/ASK signal is united modulation the input fsk signal.

3. information processing according to claim 1 and transmission equipment is characterized in that, described FSK/ASK quadrature associating modulated light signal transmission line comprises:

Erbium-doped fiber amplifier is used to improve FSK/ASK orthogonal optical signal transmission power, perhaps is amplified in the signal that has weakened in the Optical Fiber Transmission;

The single mode dispersive optical fiber is used for providing long Distance Transmission path to signal;

Dispersion compensating fiber is used for providing long Distance Transmission path to signal, and compensation simultaneously is because the optical dispersion that the single mode dispersive optical fiber produces.

4. information processing according to claim 1 and transmission equipment is characterized in that, described receiver section comprises:

Coupler is used for the signal that will the send ratio separated into two parts in power, makes it enter fsk signal receiver and ASK signal receiver respectively;

Fsk signal receiver is used to receive the signal from coupler, and isolates the optical label signal part in the orthogonal signalling, to fsk signal detect, amplification, filtering and judgement, demodulate marking signal, i.e. the header of IP packet;

The ASK signal receiver is used for direct quadrature signal and carries out intensity detection, amplification, filtering and judgement, demodulates net load.

5. information processing according to claim 4 and transmission equipment is characterized in that, described fsk signal receiver comprises:

Narrow-band optical filter is used for a peak point of filtering orthogonal signalling frequency spectrum, stays another single frequency signal information;

Photoelectric detector and preposition electric amplifier, the single-frequency optical signals that is used for being produced by narrow-band optical filter is converted into the signal of telecommunication, and the demodulation of IP header is come out, and then the faint signal of telecommunication is amplified;

Low pass filter receives the output of Photoelectric Detection and preposition electric amplifier, and IP data packet head information signal is carried out shaping, reduces the error rate of header signal;

Described ASK signal receiver comprises:

Narrow-band optical filter is used for the noise that the filtering orthogonal signalling are introduced at channel;

Photoelectric detector and preposition electric amplifier receive the output of described narrow-band optical filter, and the signal strength signal intensity of direct detection orthogonal optical signal, are about to the ASK signal and are converted into the signal of telecommunication, thereby the demodulation of IP net load is come out, and then that this is the faint signal of telecommunication amplifies;

Low pass filter receives the output of Photoelectric Detection and preposition electric amplifier, is used for the net load signal of demodulation is carried out shaping, reduces the error rate of net load signal.

6. an information processing method that is applied to information processing according to claim 1 and transmission equipment is applied to generation, transmission and the reception of information, it is characterized in that, comprising:

The generation step of FSK/ASK united orthogonal light signal:

The IP packet that a Access Network transmits at first converges at the edge router signal generator, cushions and forward error correction, and its header is separated with net load, produces the marking signal and the net load signal at a high speed of low speed;

The marking signal of b low speed is realized the FSK modulation by the FSK modulator, afterwards signal is input to the light signal input of Mach-Zehnder modulators;

C net load signal at a high speed is input to the signal of telecommunication control end of Mach-Zehnder modulators, realizes the associating light modulation of FSK/ASK by the luminous intensity of control input marking signal, and signal is input to transmission line;

The transmitting step of FSK/ASK united orthogonal light signal:

D FSK/ASK quadrature allied signal is by the amplification of fiber amplifier, and passes through the transmission of positive dispersion fiber and negative dispersion optical fiber respectively, and the optical receiver part that arrives another edge router after wavelength Conversion and the route;

The reception and the demodulation step of FSK/ASK united orthogonal light signal:

E FSK/ASK orthogonal signalling are separated coupled apparatus by a light, in the ratio of power the light signal separated into two parts are entered fsk signal receiver and ASK signal receiver respectively;

The f orthogonal signalling form simple signal by optical narrow pass band filters, by photoelectric detector this single-frequency optical signals are converted into the signal of telecommunication, and demodulate fsk signal by the filter shape device;

G is with the demodulating process of step f, and orthogonal signalling are by optical narrow pass band filters filtering noise signal and form simple signal, demodulate the ASK signal by photoelectric detector and filter shape device.

7. information processing method according to claim 6, it is characterized in that, step b, signal is directly modulated single distributed feedback laser by a little bias current, utilize the chirp of laser to produce two spectrum sign indicating number frequencies, and determine the centre wavelength of some wavelength X as laser according to the operating position of network wavelength resource with suitable deviant.

8. according to right 6,7 described information processing methods, it is characterized in that fsk signal and ASK signal are in same signal frequency, and adopt the form on road altogether.The every router of orthogonal signalling only can be realized the high speed routing forwarding of payload information by the optical label signal that extracts and handle low speed.

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