ISSN 
2003 Vol. 32, No. 3
2003, 32(3): 225-229.
Abstract:
In this paper, an overview of research on the IP over wavelength division multiplexing networks using optical path switching is presented. Three aspects of the design are emphasized. The first is the design of virtual topology, including protection design and reconfiguration algorithms. The second is on the algorithms for traffic grooming. An optical wavelength can provide huge bandwith, but the transmission rates of the services are usually much lower. Low rate services should be appropriately merged into the wavelengths in the network, which is called traffic grooming, to obtain good network performance and lower cost. The third is on the network survivability. Finally, problems for further research are discussed.
In this paper, an overview of research on the IP over wavelength division multiplexing networks using optical path switching is presented. Three aspects of the design are emphasized. The first is the design of virtual topology, including protection design and reconfiguration algorithms. The second is on the algorithms for traffic grooming. An optical wavelength can provide huge bandwith, but the transmission rates of the services are usually much lower. Low rate services should be appropriately merged into the wavelengths in the network, which is called traffic grooming, to obtain good network performance and lower cost. The third is on the network survivability. Finally, problems for further research are discussed.
2003, 32(3): 230-234.
Abstract:
In this paper, we described the existing problems in current network core equipments. From this point of view, we discussed the key requirements for the next generation core switch/router. We also mentioned several technologies will be used, such as optical backplane, very short range, broadband switch element and the structure of the switch networks.
In this paper, we described the existing problems in current network core equipments. From this point of view, we discussed the key requirements for the next generation core switch/router. We also mentioned several technologies will be used, such as optical backplane, very short range, broadband switch element and the structure of the switch networks.
2003, 32(3): 235-239.
Abstract:
The technology of HFC network is far and wide used in broadband access networks. In the HFC networks, full and precise network management is very important for ensuring the network operation, and also it is key of the network working steadily and high effectively. This paper describes a solution of HFC network managing system based upon SNMP, which includes network management platform system and workstation and proxy agent. Through general serial interface, the proxy agent can monitor local equipments, and through SNMP, the network management system exchanges information with the proxy agent, by which way it achieves remote management, and realizes HFC network's stability and high-efficiency.
The technology of HFC network is far and wide used in broadband access networks. In the HFC networks, full and precise network management is very important for ensuring the network operation, and also it is key of the network working steadily and high effectively. This paper describes a solution of HFC network managing system based upon SNMP, which includes network management platform system and workstation and proxy agent. Through general serial interface, the proxy agent can monitor local equipments, and through SNMP, the network management system exchanges information with the proxy agent, by which way it achieves remote management, and realizes HFC network's stability and high-efficiency.
2003, 32(3): 240-244.
Abstract:
A fiber-optic gyro is a kind of optical fiber sensor for the angular velocity. In this paper, the fundamental principle of fiber-optic gyro based on Sagnac effect is reviewed, and the integrated optical phase modulator, which is a key device of the gyro and is our main task in the work, are analysed. According to the yielded equations, the drive voltage and frequency bandwidth in modulation of fiber-optic gyro are calculated, and the calculation results can be contributed to a design of the modulator used in fiber-optic gyro.
A fiber-optic gyro is a kind of optical fiber sensor for the angular velocity. In this paper, the fundamental principle of fiber-optic gyro based on Sagnac effect is reviewed, and the integrated optical phase modulator, which is a key device of the gyro and is our main task in the work, are analysed. According to the yielded equations, the drive voltage and frequency bandwidth in modulation of fiber-optic gyro are calculated, and the calculation results can be contributed to a design of the modulator used in fiber-optic gyro.
2003, 32(3): 245-250.
Abstract:
This paper proposes an Adaptive Sub-Path Protection algorithm for multi-granularity traffic in WDM networks. The idea of ASPP is to partition each working path into several sub-paths, and to calculate their protection paths under shared risk link groups constraints respectively. Based on dynamic traffic with different load, the performance of ASPP has been investigated via simulations. The results show that ASPP can make the tradeoffs between the restoration utilization and recovery times.
This paper proposes an Adaptive Sub-Path Protection algorithm for multi-granularity traffic in WDM networks. The idea of ASPP is to partition each working path into several sub-paths, and to calculate their protection paths under shared risk link groups constraints respectively. Based on dynamic traffic with different load, the performance of ASPP has been investigated via simulations. The results show that ASPP can make the tradeoffs between the restoration utilization and recovery times.
2003, 32(3): 251-255.
Abstract:
The progress, fundamental principles and system structures of fiber optical code-division multiple-access(OCDMA) are introduced. Spreading sequences used in fibe OCDMA are investigated, also we summarize the schemes used to reduce multiple access interference, and several new receiver structures are given. Finally, some main techniques are proposed.
The progress, fundamental principles and system structures of fiber optical code-division multiple-access(OCDMA) are introduced. Spreading sequences used in fibe OCDMA are investigated, also we summarize the schemes used to reduce multiple access interference, and several new receiver structures are given. Finally, some main techniques are proposed.
2003, 32(3): 256-260.
Abstract:
Traffic grooming, which can effectively use lightpaths to transmit traffic streams, i.e., to multiplex many low-rate traffic streams into one lightpath to transmit, is gotten more and more research. In this paper, for a WDM grooming mesh network, with the constraints on the number of transceivers per node and wavelength continuity, adaptive routing and wavelength assignment problem is investigated, and some adaptive traffic-grooming algorithms are proposed. simulations show that joint routing algorithm performs better than others.
Traffic grooming, which can effectively use lightpaths to transmit traffic streams, i.e., to multiplex many low-rate traffic streams into one lightpath to transmit, is gotten more and more research. In this paper, for a WDM grooming mesh network, with the constraints on the number of transceivers per node and wavelength continuity, adaptive routing and wavelength assignment problem is investigated, and some adaptive traffic-grooming algorithms are proposed. simulations show that joint routing algorithm performs better than others.
2003, 32(3): 261-263.
Abstract:
In this paper, a signal demodulation method by software for high sensitivity fiber optic sensor of magnetic field is introduced. The measure pricision of the sensor is 1 nT, the minimun detectable field per unit bandwidth is 2.86×10-10 T/Hz1/2 and the dynamic range is 60 dB for the sensor. This work is very useful for detecting weak magnetic field technology and the research of interferential fiber optic sensors.
In this paper, a signal demodulation method by software for high sensitivity fiber optic sensor of magnetic field is introduced. The measure pricision of the sensor is 1 nT, the minimun detectable field per unit bandwidth is 2.86×10-10 T/Hz1/2 and the dynamic range is 60 dB for the sensor. This work is very useful for detecting weak magnetic field technology and the research of interferential fiber optic sensors.
2003, 32(3): 264-266.
Abstract:
The structure for broad-band integrated optical waveguide amplifier with thin-film filter is designed, and three structure, single path, round path and multi-path, are given, the advantage and shortcoming of different structures is compared, the advantage of single path structure is simple, shortcoming of which is lower total gain, whereas round path structure has higher gain, and fabrication of which is complex, multi-path structure is obtained with combination of the advantage of above two structures. It is shown that multi-path broad-band integrated optical amplifier structure is the best.
The structure for broad-band integrated optical waveguide amplifier with thin-film filter is designed, and three structure, single path, round path and multi-path, are given, the advantage and shortcoming of different structures is compared, the advantage of single path structure is simple, shortcoming of which is lower total gain, whereas round path structure has higher gain, and fabrication of which is complex, multi-path structure is obtained with combination of the advantage of above two structures. It is shown that multi-path broad-band integrated optical amplifier structure is the best.
2003, 32(3): 267-271.
Abstract:
The shortest path problem with complex constraints is described, and the application of deviation algorithm, a kind of k shortest paths algorithms, to this problem is introduced. The factors that affect the efficiency of the algorithm are analyzed, and an enhancement to the algorithm is proposed to improve the efficiency. Simulation results show that this enhancement is very efficient.
The shortest path problem with complex constraints is described, and the application of deviation algorithm, a kind of k shortest paths algorithms, to this problem is introduced. The factors that affect the efficiency of the algorithm are analyzed, and an enhancement to the algorithm is proposed to improve the efficiency. Simulation results show that this enhancement is very efficient.
2003, 32(3): 272-275.
Abstract:
In this paper, based on the characteristics of packet switching fabrics, performance of direct interconnection network have been analyzed in term of throughput, latency, routing algorithm and deadlock free. The research shows that ideal throughput is inversely proportional to the fabric scale. In the switch fabric employing direct interconnection networks, source routing algorithm and shortest path are more suitable in packet switching fabric. Furthermore, deadlock recovery mechanism has better utilization of resource.
In this paper, based on the characteristics of packet switching fabrics, performance of direct interconnection network have been analyzed in term of throughput, latency, routing algorithm and deadlock free. The research shows that ideal throughput is inversely proportional to the fabric scale. In the switch fabric employing direct interconnection networks, source routing algorithm and shortest path are more suitable in packet switching fabric. Furthermore, deadlock recovery mechanism has better utilization of resource.
2003, 32(3): 276-279.
Abstract:
In the paper, we analyse the problem of fiber delay lines output contention, when the bursts are delayed by fiber delay lines, and the bursts lost rate affected by the problem. The solution by introducing the tunable wavelength converter are presented and simulation results are given.
In the paper, we analyse the problem of fiber delay lines output contention, when the bursts are delayed by fiber delay lines, and the bursts lost rate affected by the problem. The solution by introducing the tunable wavelength converter are presented and simulation results are given.
2003, 32(3): 280-284.
Abstract:
This paper outlines the limitation of some currently schemes of defending SYN-Flood in traditional networks, and presents an active network based SYN-Flood defense mechanism, which takes advantage of the active network's dynamic environment. In additon, we analyze the performance of our scheme via simulation experiments and compare it with the firewall based mechanism. The experiments show that active network based mechanism provides better capability for SYN-Flood defending.
This paper outlines the limitation of some currently schemes of defending SYN-Flood in traditional networks, and presents an active network based SYN-Flood defense mechanism, which takes advantage of the active network's dynamic environment. In additon, we analyze the performance of our scheme via simulation experiments and compare it with the firewall based mechanism. The experiments show that active network based mechanism provides better capability for SYN-Flood defending.
2003, 32(3): 285-288.
Abstract:
In this paper, we put forward a scheme of realizing the source model to test the performance of switch fabric, and this it includes two kinds of source models. One, with the address happening suddenly, has balanced traffic and is used for designing the size of the buffer memory that the switch fabric needs. Another has non-balanced traffic and is used to verify the performance of the arbitration algorithm of the switch fabric. Simulation shows that this source model has satisfied the need of testing the performance of switch fabric and is useful for the research of switch fabric.
In this paper, we put forward a scheme of realizing the source model to test the performance of switch fabric, and this it includes two kinds of source models. One, with the address happening suddenly, has balanced traffic and is used for designing the size of the buffer memory that the switch fabric needs. Another has non-balanced traffic and is used to verify the performance of the arbitration algorithm of the switch fabric. Simulation shows that this source model has satisfied the need of testing the performance of switch fabric and is useful for the research of switch fabric.
2003, 32(3): 289-292.
Abstract:
Optical burst switching technique has gained considerable interest for the reason that it merges the merits of optical packet switching technique and optical circuit technique. But as far as we know, there is no research about the burst queue schemes in an optical burst switching edge node. The functional architecture of optical burst switching network edge node is briefly introduced in this paper, and the function of each part is analyzed in brief. We then present three burst queue schemes:centralized queue scheme, mixed queue scheme and individual queue scheme. Theoretical analysis and simulation results demonstrate that the centralized queue scheme is the best.
Optical burst switching technique has gained considerable interest for the reason that it merges the merits of optical packet switching technique and optical circuit technique. But as far as we know, there is no research about the burst queue schemes in an optical burst switching edge node. The functional architecture of optical burst switching network edge node is briefly introduced in this paper, and the function of each part is analyzed in brief. We then present three burst queue schemes:centralized queue scheme, mixed queue scheme and individual queue scheme. Theoretical analysis and simulation results demonstrate that the centralized queue scheme is the best.
2003, 32(3): 293-295.
Abstract:
In this paper, binary exponential backoff which is a collision resolution algorithm of DOCSIS is studied, and a novel algorithm is presented. Setting up a simulation model of these two algorithms, the result of simulation indicate that backward binary exponential backoff has lower access delay than binary exponential backoff.
In this paper, binary exponential backoff which is a collision resolution algorithm of DOCSIS is studied, and a novel algorithm is presented. Setting up a simulation model of these two algorithms, the result of simulation indicate that backward binary exponential backoff has lower access delay than binary exponential backoff.
2003, 32(3): 296-299.
Abstract:
The theory and mathematical analysis of multiwavelengh backward-pumped fiber Raman amplifier are presented, and an effective optimizing method including a improved genetic algorithm and a shooting method is presented to optimize the pump lights. By numerical simulation, 80 nm bandwidth Raman gain rippled less than 1 dB is attained, and the average on-off gain is 5.93 dB.
The theory and mathematical analysis of multiwavelengh backward-pumped fiber Raman amplifier are presented, and an effective optimizing method including a improved genetic algorithm and a shooting method is presented to optimize the pump lights. By numerical simulation, 80 nm bandwidth Raman gain rippled less than 1 dB is attained, and the average on-off gain is 5.93 dB.
2003, 32(3): 300-303,308.
Abstract:
A novel resonant-interferometric fiber optical gyroscope is proposed in the paper, the formula of optical intensity transmittance of the RIFOG's is deduced,the sensitivity of the rotation of the REFOG, RFOG and the RIFOG is compared.The system scheme of the RIFOG is designed, and as shown by the theoretical analysis, the system with 3-meter-length of polarization maintaining fiber ring-resonator and optical amplifier in it can get theoretical resolution better than 22o/h.
A novel resonant-interferometric fiber optical gyroscope is proposed in the paper, the formula of optical intensity transmittance of the RIFOG's is deduced,the sensitivity of the rotation of the REFOG, RFOG and the RIFOG is compared.The system scheme of the RIFOG is designed, and as shown by the theoretical analysis, the system with 3-meter-length of polarization maintaining fiber ring-resonator and optical amplifier in it can get theoretical resolution better than 22o/h.
2003, 32(3): 304-308.
Abstract:
The paper has studied the performance of OCDMA system with spectrum-phase en/decoder. The analysis of impact on error of code position for OCDMA system, Gained the formula of BER of system under the case. The numerical result demonstrates the control of luminous power、structure of en/decoder and choice of code sequence, which are key to OCDMA system.
The paper has studied the performance of OCDMA system with spectrum-phase en/decoder. The analysis of impact on error of code position for OCDMA system, Gained the formula of BER of system under the case. The numerical result demonstrates the control of luminous power、structure of en/decoder and choice of code sequence, which are key to OCDMA system.
2003, 32(3): 309-312.
Abstract:
The Mach-Zehnder traveling wave LiNbO3 optical modulator with thicker electrodes and relatively thicker SiO2 buffer layer have been analysed using conformal mapping, taking into account the dependence of the modulation characteristics on the thickness of electrodes and buffer layer at the same device. The relation between the parameters and the modulation characteristics, such as effective index, characteristic impedance, half-wavelength voltage and conductor loss, have been obtained to select the proper thickness of the electrodes and buffer layer to optimize the performance of the modulator. By using the calculation results, the velocity matching and impedance matching are achieved approximately to realize the broadband modulation.
The Mach-Zehnder traveling wave LiNbO3 optical modulator with thicker electrodes and relatively thicker SiO2 buffer layer have been analysed using conformal mapping, taking into account the dependence of the modulation characteristics on the thickness of electrodes and buffer layer at the same device. The relation between the parameters and the modulation characteristics, such as effective index, characteristic impedance, half-wavelength voltage and conductor loss, have been obtained to select the proper thickness of the electrodes and buffer layer to optimize the performance of the modulator. By using the calculation results, the velocity matching and impedance matching are achieved approximately to realize the broadband modulation.
2003, 32(3): 313-316.
Abstract:
This paper introduces the properties of optical power budget in TDRSS's laser communication links. For various condition of different transmission distance and divergence angle, the attenuation in space is studied in detail. According to the requirement of TDRS system, the transmitting power is also specified in the paper.
This paper introduces the properties of optical power budget in TDRSS's laser communication links. For various condition of different transmission distance and divergence angle, the attenuation in space is studied in detail. According to the requirement of TDRS system, the transmitting power is also specified in the paper.
2003, 32(3): 317-320,327.
Abstract:
This paper discussed the implementation of MIL-STD-1553/1773 bus controller in three aspects:the definition of message list storage data structure, the organiszation of the shared memory space, and the designing of the control procedure. These three aspects can be summed up into the design of the memory management unit, a core block of the bus controller's blocking design. Bus controllers applying this design will be able to process multiple messages automatically.
This paper discussed the implementation of MIL-STD-1553/1773 bus controller in three aspects:the definition of message list storage data structure, the organiszation of the shared memory space, and the designing of the control procedure. These three aspects can be summed up into the design of the memory management unit, a core block of the bus controller's blocking design. Bus controllers applying this design will be able to process multiple messages automatically.
2003, 32(3): 321-323.
Abstract:
The analysis of interdigital transducer is important in surface acoustic wave. We usually used δ function model before. Based on the basic charge distribution function, in this thesis we obtain the frequency curve of interdigital transducer in collinear acoustic-optical apparatus.
The analysis of interdigital transducer is important in surface acoustic wave. We usually used δ function model before. Based on the basic charge distribution function, in this thesis we obtain the frequency curve of interdigital transducer in collinear acoustic-optical apparatus.
2003, 32(3): 324-327.
Abstract:
This paper presents a VHDL project of Manchester encoder with FPGA implementation and releases VHDL source code of some important modules. Using QuartusⅡ2.1 of Altera company, the project has been synthesized and fitted to device APEX20KE series with speed. The result of timing simulation is accord with theory. And the timing analysis shows the data rate can be up to 22.5 Mbps.
This paper presents a VHDL project of Manchester encoder with FPGA implementation and releases VHDL source code of some important modules. Using QuartusⅡ2.1 of Altera company, the project has been synthesized and fitted to device APEX20KE series with speed. The result of timing simulation is accord with theory. And the timing analysis shows the data rate can be up to 22.5 Mbps.
2003, 32(3): 328-330.
Abstract:
The principle of distributed optical-fiber temperature sensor, based on Raman scatter and Brillouin scatter, is discussed by this paper, which adopts the frequency analytical method. The analytical method can overcome the shortcoming of the traditional temporal analytical method, which needs high-speed sample circuit. Furthermore the analytical method has broke a new path to enhance the spatial resolution of sensors. At the same time, a high spatial resolution optical-fiber sensor based on model coupling is discussed by this paper. Finally the comparison of several optical-fiber sensors are presented.
The principle of distributed optical-fiber temperature sensor, based on Raman scatter and Brillouin scatter, is discussed by this paper, which adopts the frequency analytical method. The analytical method can overcome the shortcoming of the traditional temporal analytical method, which needs high-speed sample circuit. Furthermore the analytical method has broke a new path to enhance the spatial resolution of sensors. At the same time, a high spatial resolution optical-fiber sensor based on model coupling is discussed by this paper. Finally the comparison of several optical-fiber sensors are presented.
2003, 32(3): 331-333.
Abstract:
The collinear surface acoustic wave properties that determine the induced grating parameters have been investigated using a rigorous modeling of the surface acouseic wave propagation in multiplayer. The guided-to-leaky mode conversion by the induced diffraction grating from surface acouseic wave is analyzed using a generalized multimode formulation of the coupled mode theory. Mode conversion efficiency has been calculated as functions of acoustic frequency, interaction length, guiding layer thickness, and acoustic drive power density.
The collinear surface acoustic wave properties that determine the induced grating parameters have been investigated using a rigorous modeling of the surface acouseic wave propagation in multiplayer. The guided-to-leaky mode conversion by the induced diffraction grating from surface acouseic wave is analyzed using a generalized multimode formulation of the coupled mode theory. Mode conversion efficiency has been calculated as functions of acoustic frequency, interaction length, guiding layer thickness, and acoustic drive power density.
2003, 32(3): 334-336.
Abstract:
In time-amplitude encoding and frequency hopping/time-spreading OCDM system, OMAI is the main factory witch affecting the BER and number of users.This paper is about how to decrease OMAI in these two system with technologies of improving code series, managing Dispersion,selecting line-code and proper using hard-limiter.
In time-amplitude encoding and frequency hopping/time-spreading OCDM system, OMAI is the main factory witch affecting the BER and number of users.This paper is about how to decrease OMAI in these two system with technologies of improving code series, managing Dispersion,selecting line-code and proper using hard-limiter.
2003, 32(3): 337-339.
Abstract:
This paper introduces the applications of optical devices in coarse wavelength division multiplexing system, comparing with that of dense wavelength division multiplexing system, obtains the advantages over coarse wavelength division multiplexing system, points out the RD direction further of coarse wavelength division multiplexing device at last.
This paper introduces the applications of optical devices in coarse wavelength division multiplexing system, comparing with that of dense wavelength division multiplexing system, obtains the advantages over coarse wavelength division multiplexing system, points out the RD direction further of coarse wavelength division multiplexing device at last.
2003, 32(3): 340-342.
Abstract:
The image will be distorted when we take the object's picture with CCD at long range because of atmosphere turbulence. We can't availably recognize and monitor long distance object for this reason. This article explained the theory of atmosphere turbulence and the main affection to image caused by atmosphere turbulence. The solution was given to correct image distortion. The effect of the solution is proved by experiment.
The image will be distorted when we take the object's picture with CCD at long range because of atmosphere turbulence. We can't availably recognize and monitor long distance object for this reason. This article explained the theory of atmosphere turbulence and the main affection to image caused by atmosphere turbulence. The solution was given to correct image distortion. The effect of the solution is proved by experiment.
2003, 32(3): 343-345.
Abstract:
In this paper, the transform approximation method is introduced, which gains Laplace transforms of heavy-tailed distributions approximately. It overcomes the difficulties in analyzing queue waiting time of heavy-tailed distribution sources, which haven't the Laplace transforms. It can be referred in practical design of the buffers of network queue.
In this paper, the transform approximation method is introduced, which gains Laplace transforms of heavy-tailed distributions approximately. It overcomes the difficulties in analyzing queue waiting time of heavy-tailed distribution sources, which haven't the Laplace transforms. It can be referred in practical design of the buffers of network queue.
2003, 32(3): 346-348.
Abstract:
We propose a new dynamic bandwidth allocation algorithm, which is based on grant-request method, for ethernet-passive optical network upstream multiple access scheme. It offers low latency and high bandwidth efficiency. Simulation results confirm its excellent performance.
We propose a new dynamic bandwidth allocation algorithm, which is based on grant-request method, for ethernet-passive optical network upstream multiple access scheme. It offers low latency and high bandwidth efficiency. Simulation results confirm its excellent performance.
