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2004 Vol. 26, No. 1
Display Method:
2004, 26(1): 1-6.
Abstract:
Constrained by the price and technology, not only the wavelength converters laid in WDM network but also the Wavelength Per Fiber (WPF) is limited. But there are usually some spare fibers in links, so it is important to make full use of these fibers to lower the blocking probability in WDM networks. This paper proposes a sparse multifiber and wavelength assignment algorithm based on dynamic traffic service WDM-networks. The simulation results show that by assigning sparse multifiber, the blocking performance can be obtained with fewer number of WPF.
Constrained by the price and technology, not only the wavelength converters laid in WDM network but also the Wavelength Per Fiber (WPF) is limited. But there are usually some spare fibers in links, so it is important to make full use of these fibers to lower the blocking probability in WDM networks. This paper proposes a sparse multifiber and wavelength assignment algorithm based on dynamic traffic service WDM-networks. The simulation results show that by assigning sparse multifiber, the blocking performance can be obtained with fewer number of WPF.
2004, 26(1): 7-13.
Abstract:
Multicast is a preferred communication technique in multiple recipients and its importance is rapidly growing. The Internet Group Management: Protocol(IGMP) does not provide access control of the members. To provide communication confidentiality, traffic in secure multicast is encrypted with a session key known only by certified group members. Whenever there is a change in the group membership, the key has to be updated dynamically, thus key management is indicated as the sticking point in secure multicast rescarch. To be applicable to large scale multicast, hierarchical structure is introduced as a solution to the scalability problem of group key management. The paper addresses the logical key hierarchy and concentrates on the optimal structure problem of the key tree. A theoretical analysis is given in the paper with the result in correspondence with a previous experimental conclusion.
Multicast is a preferred communication technique in multiple recipients and its importance is rapidly growing. The Internet Group Management: Protocol(IGMP) does not provide access control of the members. To provide communication confidentiality, traffic in secure multicast is encrypted with a session key known only by certified group members. Whenever there is a change in the group membership, the key has to be updated dynamically, thus key management is indicated as the sticking point in secure multicast rescarch. To be applicable to large scale multicast, hierarchical structure is introduced as a solution to the scalability problem of group key management. The paper addresses the logical key hierarchy and concentrates on the optimal structure problem of the key tree. A theoretical analysis is given in the paper with the result in correspondence with a previous experimental conclusion.
2004, 26(1): 14-19.
Abstract:
The characteristics of the network management service access in the Telecommunication Management Network (TMN) arc analyzed. According to these characteristics, the Network Management Service Access Model(NMSAM) applying extensible Markup Lan-guage(XML) and Model-View-Controller (MVC) architecture is presented. The implementation of the NMSAM is also given.
The characteristics of the network management service access in the Telecommunication Management Network (TMN) arc analyzed. According to these characteristics, the Network Management Service Access Model(NMSAM) applying extensible Markup Lan-guage(XML) and Model-View-Controller (MVC) architecture is presented. The implementation of the NMSAM is also given.
2004, 26(1): 20-26.
Abstract:
This paper analyzes the feature of W-CDMA downlink OVSF code. A novel dynamic sequential allocation algorithm is presented according to code blocking ratio in the stochastic allocation. Low level codes are allocated firstly, and codes in the same level are allocated sequentially by order from low to high. The algorithm flow and system implemen-tation is specified. Finally, theoretical analysis and system simulation are presented. It is proved that it greatly reduces the code blocking probability and system overhead , which is valuable for engineering applications.
This paper analyzes the feature of W-CDMA downlink OVSF code. A novel dynamic sequential allocation algorithm is presented according to code blocking ratio in the stochastic allocation. Low level codes are allocated firstly, and codes in the same level are allocated sequentially by order from low to high. The algorithm flow and system implemen-tation is specified. Finally, theoretical analysis and system simulation are presented. It is proved that it greatly reduces the code blocking probability and system overhead , which is valuable for engineering applications.
2004, 26(1): 27-34.
Abstract:
A Coherent Delay-Locked Loop(CDLL) is proposed based on interpolation and integrate/dump filter for PN code tracking in DS-CDMA systems. The performance of the CDLL is investigated under AWGN and multi-user environments, and closed-form expres-sions for the timing adjustment error probability, steady-state timing squared root error, probability and Mean Time to Lose Lock (MTLL) are derived by employing appropriate Markov chain models. Finally, some numerical results are presented and analysis shows that those results also perform well in single path fading environment. The delay-locked loop is applied to the development of WCDMA BTS and WCDMA MT.
A Coherent Delay-Locked Loop(CDLL) is proposed based on interpolation and integrate/dump filter for PN code tracking in DS-CDMA systems. The performance of the CDLL is investigated under AWGN and multi-user environments, and closed-form expres-sions for the timing adjustment error probability, steady-state timing squared root error, probability and Mean Time to Lose Lock (MTLL) are derived by employing appropriate Markov chain models. Finally, some numerical results are presented and analysis shows that those results also perform well in single path fading environment. The delay-locked loop is applied to the development of WCDMA BTS and WCDMA MT.
2004, 26(1): 35-40.
Abstract:
This paper first proposes the prototype algorithm of an improved distributed power control (IDPC). In this algorithm, mobile units adjust their transmitter powers ac-cording to not only their power levels at last iterative step but also the largest and second smallest eigenvalues of the link gain matrix at current time instant. As for the prototype algorithm, link gains for all mobile units must be measured and large burden may be brought in at base stations. For this reason, the prototype algorithm is developed further in a dis-tributed way and thus lead to IDPC algorithm, in which both the positive receiver noise and constrained transmitter power are also considered. As a result, with IDPC algorithm, the CIRs are balanced quickly and a superior outage performance to other algorithms is reached.
This paper first proposes the prototype algorithm of an improved distributed power control (IDPC). In this algorithm, mobile units adjust their transmitter powers ac-cording to not only their power levels at last iterative step but also the largest and second smallest eigenvalues of the link gain matrix at current time instant. As for the prototype algorithm, link gains for all mobile units must be measured and large burden may be brought in at base stations. For this reason, the prototype algorithm is developed further in a dis-tributed way and thus lead to IDPC algorithm, in which both the positive receiver noise and constrained transmitter power are also considered. As a result, with IDPC algorithm, the CIRs are balanced quickly and a superior outage performance to other algorithms is reached.
2004, 26(1): 41-46.
Abstract:
In this paper, two location algorithms, i.e. Chan and Taylor series expansion methods, are analyzed and a cooperative location method based on Chan and Taylor algorithms is proposed. The performance of the cooperative location method is simulated under different channel environments, and the results show that the cooperative location method can significantly improve the location accuracy under bad channel environments.
In this paper, two location algorithms, i.e. Chan and Taylor series expansion methods, are analyzed and a cooperative location method based on Chan and Taylor algorithms is proposed. The performance of the cooperative location method is simulated under different channel environments, and the results show that the cooperative location method can significantly improve the location accuracy under bad channel environments.
2004, 26(1): 47-52.
Abstract:
A simple transmit diversity technique assumes that channel does not change over two symbol period of time. Therefore, this technique is not suitable for time varying channels. This paper modifies the transmit diversity technique to accommodate time varying channel (mobile multipath channel). Simulation results show that the proposed modification works well in fast varying channel.
A simple transmit diversity technique assumes that channel does not change over two symbol period of time. Therefore, this technique is not suitable for time varying channels. This paper modifies the transmit diversity technique to accommodate time varying channel (mobile multipath channel). Simulation results show that the proposed modification works well in fast varying channel.
2004, 26(1): 53-59.
Abstract:
The Crosspower Spectrum Phase (CSP) technique is a well known time delay estimation method. A relatively precise time delay estimation can be achieved by using it in the environment of weak noise and medium reverberation. The performance degrades sharply in the environment of low SNR and strong reverberation. The modified CSP algorithm is proposed in order to improve the performance of CSP. The weighting function of the proposed CSP method changes with the variation of SNR, and the time delay of arrival is accomplished via a weighted function of frames of CSP. Computer simulation results indicate that the proposed method will give satisfactory value of time delay estimation even in the environment of low SNR and strong reverberation.
The Crosspower Spectrum Phase (CSP) technique is a well known time delay estimation method. A relatively precise time delay estimation can be achieved by using it in the environment of weak noise and medium reverberation. The performance degrades sharply in the environment of low SNR and strong reverberation. The modified CSP algorithm is proposed in order to improve the performance of CSP. The weighting function of the proposed CSP method changes with the variation of SNR, and the time delay of arrival is accomplished via a weighted function of frames of CSP. Computer simulation results indicate that the proposed method will give satisfactory value of time delay estimation even in the environment of low SNR and strong reverberation.
2004, 26(1): 60-64.
Abstract:
By exploiting wavelet packet transform to analyze signals both in time and frequency space, this paper researches the statistic property of non-Gaussian stationary noise and its signal structure. The results of classic optimum detector arc extended to the condition where the distribution of background noise is non-Gaussian and a new signal detection algorithm in non-Gaussian background noise is given. The simulated result justifies this method.
By exploiting wavelet packet transform to analyze signals both in time and frequency space, this paper researches the statistic property of non-Gaussian stationary noise and its signal structure. The results of classic optimum detector arc extended to the condition where the distribution of background noise is non-Gaussian and a new signal detection algorithm in non-Gaussian background noise is given. The simulated result justifies this method.
2004, 26(1): 65-71.
Abstract:
Rijndael was selected as the AES. The best-known attack against Rijndael is still the one presented by the designers called Square attack. Square attack is a chosen plaintext attack. In this paper a new kind of attack called Inverse Square attack is presented which is a kind of chosen cipher text attack and better than Square attack. It also shows that if only inverse the moving direction of RotByte transformation of key schedule, the complexity of the attack will be 2~8-factor bellow the complexity of Square attack.
Rijndael was selected as the AES. The best-known attack against Rijndael is still the one presented by the designers called Square attack. Square attack is a chosen plaintext attack. In this paper a new kind of attack called Inverse Square attack is presented which is a kind of chosen cipher text attack and better than Square attack. It also shows that if only inverse the moving direction of RotByte transformation of key schedule, the complexity of the attack will be 2~8-factor bellow the complexity of Square attack.
2004, 26(1): 72-76.
Abstract:
The composite attack on sequence cipher is developed and forward feedback network is analyzed by the composition of correlation attack and inversion attack, both theory and experimental results show its complexity. Finally, comparison with normal attack is given.
The composite attack on sequence cipher is developed and forward feedback network is analyzed by the composition of correlation attack and inversion attack, both theory and experimental results show its complexity. Finally, comparison with normal attack is given.
2004, 26(1): 77-81.
Abstract:
An anti-jamming space-time adaptive processor rank-reduced by Multistage Nested Winner Filter(MSNWF) is presented in this paper. Such processor can overcome the need of freedom degrees in traditional array processing while maintains the computa-tional complexity requirements at a low level. Simulations proved such a processor can provide more freedom degrees under janimering senario and the ability to identify interfer-ences in a multidimensional spectrum at the AOA-frequency coordinates. Simulations also proved a low rank (D=10) is enough for the MSNWF space-time processor to approximate its full rank performance.
An anti-jamming space-time adaptive processor rank-reduced by Multistage Nested Winner Filter(MSNWF) is presented in this paper. Such processor can overcome the need of freedom degrees in traditional array processing while maintains the computa-tional complexity requirements at a low level. Simulations proved such a processor can provide more freedom degrees under janimering senario and the ability to identify interfer-ences in a multidimensional spectrum at the AOA-frequency coordinates. Simulations also proved a low rank (D=10) is enough for the MSNWF space-time processor to approximate its full rank performance.
2004, 26(1): 82-88.
Abstract:
A novel algorithm is proposed based on the genetic theory, which has global optimum searching characteristic. Meanwhile, considering its computational cost, decimal code, not binary one is used in operation of the operators. Moreover, a modified adaptive weights training algorithm is also used to resolve the weights fluctuant problem in stable range. Numerical simulations demonstrate that tlie genetic algorithm can converge at the global extremum quickly, and that weights estimation with the modified adaptive weights training algorithm have a more stable range, and the filtering performance has been improved obviously.
A novel algorithm is proposed based on the genetic theory, which has global optimum searching characteristic. Meanwhile, considering its computational cost, decimal code, not binary one is used in operation of the operators. Moreover, a modified adaptive weights training algorithm is also used to resolve the weights fluctuant problem in stable range. Numerical simulations demonstrate that tlie genetic algorithm can converge at the global extremum quickly, and that weights estimation with the modified adaptive weights training algorithm have a more stable range, and the filtering performance has been improved obviously.
2004, 26(1): 89-94.
Abstract:
The condition number of sensitivity matrix is a key factor that influences the performance of InSAR calibration. On the basis of InSAR calibration theory, basic principles of locating calibrators are proposed, and constraints of locating calibrators are also derived. Under the theory of condition number minimization, an algorithm of locating calibrators is presented to minimize the sensitivity matrix condition number. Theoretic analyses and computing results show that the algorithm is efficient.
The condition number of sensitivity matrix is a key factor that influences the performance of InSAR calibration. On the basis of InSAR calibration theory, basic principles of locating calibrators are proposed, and constraints of locating calibrators are also derived. Under the theory of condition number minimization, an algorithm of locating calibrators is presented to minimize the sensitivity matrix condition number. Theoretic analyses and computing results show that the algorithm is efficient.
2004, 26(1): 95-99.
Abstract:
From the difference of imaging geometry between spaceborne SAR, and airborne SAR, traditional formula computing the azimuth resolution of airborne SAR working on spotlight mode will bring big errors if it is used for spaceborne SAR. In this paper, the new formula of the azimuth resolution for spaceborne spotlight SAR. is presented, and the data simulation results validate the validity of the new method.
From the difference of imaging geometry between spaceborne SAR, and airborne SAR, traditional formula computing the azimuth resolution of airborne SAR working on spotlight mode will bring big errors if it is used for spaceborne SAR. In this paper, the new formula of the azimuth resolution for spaceborne spotlight SAR. is presented, and the data simulation results validate the validity of the new method.
2004, 26(1): 100-106.
Abstract:
The high stability of frequency sources is the foundation to the phase synchronization of the Bistatic Synthetic Aperture Radar (BiSAR) system. This paper analyzcs the influence of various frequence instabilities of sources in transmitter and receiver to the BiSAR imaging, and demonstrates the requirement to the source stability. The computer simulation results of BiSAR imaging with four types of frequency instabilities are presented.
The high stability of frequency sources is the foundation to the phase synchronization of the Bistatic Synthetic Aperture Radar (BiSAR) system. This paper analyzcs the influence of various frequence instabilities of sources in transmitter and receiver to the BiSAR imaging, and demonstrates the requirement to the source stability. The computer simulation results of BiSAR imaging with four types of frequency instabilities are presented.
2004, 26(1): 107-111.
Abstract:
For spaceborne Synthetic Aperture Radar (SAR), Dopplcr property is one of the most important factors for azimuth performance. In this paper, the elliptic orbit is applied. The Doppler centroid frequency and Doppler frequency rate are evaluated in different orbit angle with the affection of attitude error considered. And the comparison with circular orbit is given. Finally, yaw steering is discussed.
For spaceborne Synthetic Aperture Radar (SAR), Dopplcr property is one of the most important factors for azimuth performance. In this paper, the elliptic orbit is applied. The Doppler centroid frequency and Doppler frequency rate are evaluated in different orbit angle with the affection of attitude error considered. And the comparison with circular orbit is given. Finally, yaw steering is discussed.
2004, 26(1): 112-117.
Abstract:
According to the requirements of engineering design for High-Frequency Surface Wave Radar (HF-SWR), at first, a small broadband transmitting antenna is optimized based on the theory of log periodic antennas. Then, based on the end-fire array theory, a small broadband twin-whip antenna with big forward to backward ratio is designed. And six twin-whip antennas are used as the fundrnental element to form 12 side plane array system. The working principle of 12 side array and the log periodic antennas are analyzed, and calculating result is given in this paper. A practical broadband antenna system for HF-SWR is designed.
According to the requirements of engineering design for High-Frequency Surface Wave Radar (HF-SWR), at first, a small broadband transmitting antenna is optimized based on the theory of log periodic antennas. Then, based on the end-fire array theory, a small broadband twin-whip antenna with big forward to backward ratio is designed. And six twin-whip antennas are used as the fundrnental element to form 12 side plane array system. The working principle of 12 side array and the log periodic antennas are analyzed, and calculating result is given in this paper. A practical broadband antenna system for HF-SWR is designed.
2004, 26(1): 118-123.
Abstract:
In this paper, a new dielectric layer PBG structures in waveguide is introduced, and numerical analysis to its stop-band characteristic is finished. The design of PBG structures and the effect of the size of period, the number of periods, the size of unit etc. are presented. And the conclusion is presented too. It is easy to design and manufacture waveguide filter using dielectric layer PBG structures.
In this paper, a new dielectric layer PBG structures in waveguide is introduced, and numerical analysis to its stop-band characteristic is finished. The design of PBG structures and the effect of the size of period, the number of periods, the size of unit etc. are presented. And the conclusion is presented too. It is easy to design and manufacture waveguide filter using dielectric layer PBG structures.
2004, 26(1): 124-130.
Abstract:
A multiple phase partial scan design method that breaks critical cycles using a combination of valid circuit state information and conflict analysis is proposed. It is quite cost-effective to obtain circuit state information via logic simulation, therefore, circuit state information is iteratively updated after a given number of partial scan flip-fiops being selected. When all critical cycles in the circuit are broken, our method turns to the con-flict resolution process using an intensive conflict-analysis-based testability measure conflict rather than reducing the sequential depth. The proposed method tries to eliminate the con-flicts and uses a conflict-analysis-based testability measure conflict. Sufficient experimental results are presented to validate the method.
A multiple phase partial scan design method that breaks critical cycles using a combination of valid circuit state information and conflict analysis is proposed. It is quite cost-effective to obtain circuit state information via logic simulation, therefore, circuit state information is iteratively updated after a given number of partial scan flip-fiops being selected. When all critical cycles in the circuit are broken, our method turns to the con-flict resolution process using an intensive conflict-analysis-based testability measure conflict rather than reducing the sequential depth. The proposed method tries to eliminate the con-flicts and uses a conflict-analysis-based testability measure conflict. Sufficient experimental results are presented to validate the method.
2004, 26(1): 131-136.
Abstract:
On the basis of the introduction of the integrated-service access system, this paper introduces a new kind of scheduling scheme called priority-based parameter self-adapting round-robin I/O scheduling, and the implementation of this scheme in integrated-service access system is presented. The performances of several scheduling schemes are tested and compared in this paper.
On the basis of the introduction of the integrated-service access system, this paper introduces a new kind of scheduling scheme called priority-based parameter self-adapting round-robin I/O scheduling, and the implementation of this scheme in integrated-service access system is presented. The performances of several scheduling schemes are tested and compared in this paper.
2004, 26(1): 137-141.
Abstract:
The chaos generation neural network based on the excellent learning ability and synaptic weight database are built to generate many chaotic spread-spectrum sequences trained by the modified back-propagation algorithm with various discrete chaotic time series. The chaotic sequences are very easily generated by changing weights of neural network model, and their number is large. The computer simulation results show that the output chaotic sequences have good correlation property, balance property and linear complexity, therefore they are good candidates for the optimal encrypting code and the spread spectrum code.
The chaos generation neural network based on the excellent learning ability and synaptic weight database are built to generate many chaotic spread-spectrum sequences trained by the modified back-propagation algorithm with various discrete chaotic time series. The chaotic sequences are very easily generated by changing weights of neural network model, and their number is large. The computer simulation results show that the output chaotic sequences have good correlation property, balance property and linear complexity, therefore they are good candidates for the optimal encrypting code and the spread spectrum code.
2004, 26(1): 142-145.
Abstract:
In this paper, a controlling chaos method of the orbit space compression is proposed for a Chaotic Neural Network(CNN). The computer simulation of the chaotic behaviors of the CNN proves that each pattern can be controlled using the orbit space compression. Starting from any initial state the CNN can converge in a stored pattern or its inverse pattern, which has the smallest Hamming distance with the initial state. The controlling method of the orbit space compression shows clear physical meaning and can be easily carried out.
In this paper, a controlling chaos method of the orbit space compression is proposed for a Chaotic Neural Network(CNN). The computer simulation of the chaotic behaviors of the CNN proves that each pattern can be controlled using the orbit space compression. Starting from any initial state the CNN can converge in a stored pattern or its inverse pattern, which has the smallest Hamming distance with the initial state. The controlling method of the orbit space compression shows clear physical meaning and can be easily carried out.
2004, 26(1): 146-150.
Abstract:
The linearly constrained adaptive beamformer is hypersensitive to the amplitude and phase errors of antenna array when the signal-to-noise ratio exceeds a certain threshold. Even if the array imperfections are slight, the beamformer suppresses the desired signals as if they are interference signals. In this paper, a robust adaptive beamformer in the presence of array imperfections is presented by improving the block matrix of the generalized side lobe canceller. Since this method is based on the structure of the generalize side lobe canceller, it is convenient to use its partial adaptive processing to reduce the computation load.
The linearly constrained adaptive beamformer is hypersensitive to the amplitude and phase errors of antenna array when the signal-to-noise ratio exceeds a certain threshold. Even if the array imperfections are slight, the beamformer suppresses the desired signals as if they are interference signals. In this paper, a robust adaptive beamformer in the presence of array imperfections is presented by improving the block matrix of the generalized side lobe canceller. Since this method is based on the structure of the generalize side lobe canceller, it is convenient to use its partial adaptive processing to reduce the computation load.
2004, 26(1): 151-156.
Abstract:
The Matching Pursuit(MP) algorithms display good performance of recurring the orthonormal sparse structure of signals, but the signal decomposition process widely ex-hibits pre-echo artifact and local mismatch, so HRP algorithm was proposed by S. Jaggi, et al. to acquire more exact inner structure of signals. Unfortunely HRP algorithm is followed by more huge operation cost. The fast HRP algorithm is advanced at wavelet domain by tak-ing advantage of wavelet multiresolution decomposition, and a parallel algorithm framework is used to further reduce operation time. Theory and simulation trials indicate that HRP algorithm at wavelet domain not only reduces HRP operation cost greatly, but also improves the effect of the wavelet analysis, thus it is a promising technique applied in adaptive signal decomposition and feature extraction.
The Matching Pursuit(MP) algorithms display good performance of recurring the orthonormal sparse structure of signals, but the signal decomposition process widely ex-hibits pre-echo artifact and local mismatch, so HRP algorithm was proposed by S. Jaggi, et al. to acquire more exact inner structure of signals. Unfortunely HRP algorithm is followed by more huge operation cost. The fast HRP algorithm is advanced at wavelet domain by tak-ing advantage of wavelet multiresolution decomposition, and a parallel algorithm framework is used to further reduce operation time. Theory and simulation trials indicate that HRP algorithm at wavelet domain not only reduces HRP operation cost greatly, but also improves the effect of the wavelet analysis, thus it is a promising technique applied in adaptive signal decomposition and feature extraction.
2004, 26(1): 157-162.
Abstract:
The cluster micro-satellite Synthetic Aperture Radar(SAR) system is an inno-vative SAR system brought forward recently. In the cluster micro-satellite system, tech-nology of cross-track interferometic SAR imaging processing is studied. The influence of the rotating of the cluster micro-satellite on the baseline and the interferometric phase is analyzed. The corrected formula of the baseline and the interferometric phase are derived. By computer simulation, the errors between corrected and uncorrected height measurement are compared. The analysis results verify the correction of the formula and the necessity to correct the baseline and the phase.
The cluster micro-satellite Synthetic Aperture Radar(SAR) system is an inno-vative SAR system brought forward recently. In the cluster micro-satellite system, tech-nology of cross-track interferometic SAR imaging processing is studied. The influence of the rotating of the cluster micro-satellite on the baseline and the interferometric phase is analyzed. The corrected formula of the baseline and the interferometric phase are derived. By computer simulation, the errors between corrected and uncorrected height measurement are compared. The analysis results verify the correction of the formula and the necessity to correct the baseline and the phase.
