Showing papers by "Beijing University of Posts and Telecommunications published in 2008"
TL;DR: This communication shows that the basic ideas of UDP and LPP are identical, and UDP is just a simplified version of LPP on the assumption that the local density is uniform.
Abstract: In (Yang et al, 2007), UDP is proposed to address the limitation of LPP for the clustering and classification tasks In this communication, we show that the basic ideas of UDP and LPP are identical In particular, UDP is just a simplified version of LPP on the assumption that the local density is uniform
389 citations
TL;DR: In this paper, a quantum secure direct communication protocol with entanglement-type entangled states was proposed, and the security of the protocol was analyzed and proved to be secure in ideal conditions.
Abstract: In this paper, a quantum secure direct communication protocol with $\ensuremath{\chi}$-type entangled states ${\ensuremath{\mid}{\ensuremath{\chi}}^{00}⟩}_{3214}$ is proposed. We analyze the security of this protocol and prove that it is secure in ideal conditions. Then, an alternative way is presented to ensure the security of this protocol in a noisy channel. Moreover, this protocol utilizes quantum superdense coding to achieve a high intrinsic efficiency and source capacity. The practical implementation of this protocol is also discussed.
218 citations
01 Jun 2008
TL;DR: In this article, the existence of positive solutions to a second-order Sturm-Liouville boundary-value problem with impulsive effects was investigated, and the ideas involved differential inequalities and variational methods.
Abstract: In this paper, we investigate the existence of positive solutions to a second-order Sturm–Liouville boundary-value problem with impulsive effects. The ideas involve differential inequalities and variational methods.
185 citations
08 Dec 2008
TL;DR: A Spectrum-Tree base On-Demand routing protocol (STOD-RP) is proposed where a spectrum-tree is built in each spectrum band to address the cooperation between spectrum decision and route selection in an efficient way.
Abstract: A unique challenge for routing in cognitive radio networks is the collaboration between the route selection and spectrum decision. To solve this problem, in this paper a Spectrum-Tree base On-Demand routing protocol (STOD-RP) is proposed where a spectrum-tree is built in each spectrum band. The formation of the spectrum-tree addresses the cooperation between spectrum decision and route selection in an efficient way. In addition, a new route metric is proposed as well as a fast and efficient spectrum-adaptive route recovery method. Simulation results show that our proposed STOD-RP reduces the control overhead and shortens the average end-to-end delay significantly.
164 citations
TL;DR: Through tuning the birefringence fiber filter, the lasing wavelength can be accurately tuned in the free spectrum range of the in-line periodic filter.
Abstract: We have proposed and demonstrated a multiwavelength fiber laser based on nonlinear polarization rotation (NPR). The mechanism for stable room-temperature multiwavelength operation contributes to the ability of the intensity-dependent loss in NPR to effectively alleviate mode competition. In addition, through tuning the birefringence fiber filter, the lasing wavelength can be accurately tuned in the free spectrum range of the in-line periodic filter.
156 citations
TL;DR: A Comment on the Letter by [Sascha Gaertner et al., Phys. Rev. Lett. 100, 070504 (2008) is given in this article.
Abstract: A Comment on the Letter by [Sascha Gaertner et al., Phys. Rev. Lett. 100, 070504 (2008)]. The authors of the Letter offer a Reply.
146 citations
24 Oct 2008
TL;DR: An overview of the DRX cycle adjustable feature of the LTE power saving mechanism and further modeling the mechanism with bursty packet data traffic using a semi-Markov process show that LTE DRX achieves power saving gains over UMTS DRX at the price of prolonging wake-up delay.
Abstract: Long-term evolution (LTE) of the UMTS terrestrial radio access and radio access network is considered to ensure the competitiveness of 3GPP radio-access technology in a longer time frame. To minimize/optimize the user equipment (UE) power consumption, and further to support various services and large amount of data transmissions, a discontinuous reception (DRX) mechanism with adjustable DRX cycles has been adopted in LTE RRC_CONNECTED mode. In this paper, we take an overview of the DRX cycle adjustable feature of the LTE power saving mechanism and further modeling the mechanism with bursty packet data traffic using a semi-Markov process. The analytical results, which are validated against simulation experiments, show that LTE DRX achieves power saving gains over UMTS DRX at the price of prolonging wake-up delay. Based on the analytical model, effects of the DRX parameters on the power saving and wake-up delay performance are also investigated, and the results verify a trade-off relationship between the power saving and wake-up delay performance.
144 citations
TL;DR: From the perspective of information theory and cryptography, the security of two quantum dialogue protocols and a bidirectional quantum secure direct communication (QSDC) protocol was analyzed, and it was pointed out that the transmitted information would be partly leaked out in them.
Abstract: From the perspective of information theory and cryptography, the security of two quantum dialogue protocols and a bidirectional quantum secure direct communication (QSDC) protocol was analyzed, and it was pointed out that the transmitted information would be partly leaked out in them. That is, any eavesdropper can elicit some information about the secrets from the public annunciations of the legal users. This phenomenon should have been strictly forbidden in a quantum secure communication. In fact, this problem exists in quite a few recent proposals and, therefore, it deserves more research attention in the following related study.
138 citations
TL;DR: The simulation results on web service selection with global QoS constraints have shown that prematurity was overcomed effectively, and convergence and stability of genetic algorithm were improved greatly.
138 citations
19 May 2008
TL;DR: The proof to the optimality of sorted subcarrier pairing for AF and DF relaying without diversity is provided, which, combined with optimal power allocation, can offer further performance gain.
Abstract: We consider a two-hop relaying network in which orthogonal frequency division multiplexing (OFDM) is employed for the source-to-destination, the source-to-relay and the relay- to-destination links. Amplify-and-forward (AF) and decode-and- forward (DF) policies are both discussed with or without two-hop diversity, respectively, for the relaying network with a sum-power constraint. An unified approach is used for optimal power allocation in the four different relaying scenarios. First, equivalent channel gains are developed for any given subcarrier pair in each scenario, and then optimal power allocation can be obtained by applying the classic water-filling method. Moreover, we provide the proof to the optimality of sorted subcarrier pairing for AF and DF relaying without diversity, which, combined with optimal power allocation, can offer further performance gain.
127 citations
TL;DR: In this article, the authors analyze the security of two quantum dialogue protocols and a bidirectional quantum secure direct communication (QSDC) protocol, and point out that the transmitted information would be partly leaked out in them.
Abstract: From the perspective of information theory and cryptography, we analyze the security of two quantum dialogue protocols and a bidirectional quantum secure direct communication (QSDC) protocol, and point out that the transmitted information would be partly leaked out in them. That is, any eavesdropper can elicit some information about the secrets from the public annunciations of the legal users. This phenomenon should have been strictly forbidden in a quantum secure communication. In fact, this problem exists in quite a few recent proposals and, therefore, it deserves more research attention in the following related study.
TL;DR: From both theoretical and simulation results, the study shows that in multiuser PMP TAS/MRC systems an diversity order equals to the product of the number of transmit antennas, number of receive antennas and number of users; what's more, users plays a key role in the system performance and can be viewed as equivalent "virtual" transmit antennas.
Abstract: In this paper, a framework is presented to analyze the performance of multiuser diversity (MUD) in multiuser point-to-multipoint (PMP) MIMO systems with antenna selection. Based on this framework, the tight closed-form expressions of outage capacity and average symbol error rate are derived for the multiuser transmit antenna selection with maximal-ratio combining (TAS/MRC) system, by which we show how and with what characteristics antenna selection gains, MIMO antenna configurations and fading gains impact on the system performance, with an emphasis on the study of multiuser diversity influence. From both theoretical and simulation results, our study shows that in multiuser PMP TAS/MRC systems an diversity order equals to the product of the number of transmit antennas, number of receive antennas and number of users can be achieved; what's more, users plays a key role in the system performance and can be viewed as equivalent "virtual" transmit antennas, which is the source of the multiuser diversity inherent exists in the multiuser system. This kind of diversity can be efficiently extracted in the design of multiantenna systems.
13 Jan 2008
TL;DR: A new collaborative filtering approach TBCF (Tag-based Collaborative Filtering) based on the semantic distance among tags assigned by different users to improve the effectiveness of neighbor selection, which has significant improvement against the traditional cosine-based recommendation method while leveraging user input not explicitly targeting the recommendation system.
Abstract: Considering the natural tendency of people to follow direct or indirect cues of other people's activities, collaborative filtering-based recommender systems often predict the utility of an item for a particular user according to previous ratings by other similar users. Consequently, effective searching for the most related neighbors is critical for the success of the recommendations. In recent years, collaborative tagging systems with social bookmarking as their key component from the suite of Web 2.0 technologies allow users to freely bookmark and assign semantic descriptions to various shared resources on the web. While the list of favorite web pages indicates the interests or taste of each user, the assigned tags can further provide useful hints about what a user thinks of the pages.In this paper, we propose a new collaborative filtering approach TBCF (Tag-based Collaborative Filtering) based on the semantic distance among tags assigned by different users to improve the effectiveness of neighbor selection. That is, two users could be considered similar not only if they rated the items similarly, but also if they have similar cognitions over these items. We tested TBCF on real-life datasets, and the experimental results show that our approach has significant improvement against the traditional cosine-based recommendation method while leveraging user input not explicitly targeting the recommendation system.
TL;DR: This work proposes the use of statistical parameters of VAG signals, including the form factor involving the variance of the signal and its derivatives, skewness, kurtosis, and entropy, to classify V AG signals as normal or abnormal.
Abstract: Externally detected vibroarthrographic (VAG) signals bear diagnostic information related to the roughness, softening, breakdown, or the state of lubrication of the articular cartilage surfaces of the knee joint. Analysis of VAG signals could provide quantitative indices for noninvasive diagnosis of articular cartilage breakdown and staging of osteoarthritis. We propose the use of statistical parameters of VAG signals, including the form factor involving the variance of the signal and its derivatives, skewness, kurtosis, and entropy, to classify VAG signals as normal or abnormal. With a database of 89 VAG signals, screening efficiency of up to 0.82 was achieved, in terms of the area under the receiver operating characteristics curve, using a neural network classifier based on radial basis functions.
20 Dec 2008
TL;DR: It is revealed in this paper that the form of the transforms and the parameters chosen in his implementation weaken the many-to-one property, which results in the possible recovery of original minutiae from one transformed template.
Abstract: Cancelable biometrics may be a good approach to address the security and privacy concerns on biometric authentication. It uses some parameterized transforms to convert an original biometric template into a new version for authentication. The security of cancelable biometrics lies on noninvertibility of the transformed template, that is, the transforms should be noninvertible so that the original template can not be recovered. One way to achieve the noninvertibilty is through the use of many-to-one transforms. The idea of Ratha?s scheme of generating fingerprint templates just depends on this. However, it is revealed in this paper that the form of the transforms and the parameters chosen in his implementation weaken the many-to-one property. This results in the possible recovery of original minutiae from one transformed template.
TL;DR: A scheme of multiparty quantum secret sharing of classical messages (QSSCM) is proposed based on single photons and local unitary operations, where only the sender and one of the agents are required to store photons.
TL;DR: It is shown that quantum teleportation can be employed to weaken the role of the order-rearrangement encryption at least in a certain circumstance.
Abstract: The quantum secure direct communication (QSDC) protocol with a random basis and order is analysed and an effective attack, i.e. teleportation attack, is presented. An eavesdropper can obtain half of the transmitted secret bits with the help of this special attack. It is shown that quantum teleportation can be employed to weaken the role of the order-rearrangement encryption at least in a certain circumstance. Meanwhile, a possible improvement on this protocol is proposed, which makes it secure against this kind of attack.
TL;DR: The soliton interaction is investigated based on solving the higher-order nonlinear Schrödinger equation with the effects of third-order dispersion, self-steepening, and stimulated Raman scattering and using Hirota's bilinear method the analytic one-, two-, and three-soliton solutions are obtained.
Abstract: The soliton interaction is investigated based on solving the higher-order nonlinear Schr\"odinger equation with the effects of third-order dispersion, self-steepening, and stimulated Raman scattering. By using Hirota's bilinear method, the analytic one-, two-, and three-soliton solutions of this model are obtained. According to those solutions, the relevant properties and features of physical and optical interest are illustrated. The results of this paper will be valuable to the study of signal amplification and pulse compression.
TL;DR: In this article, a Wilkinson power divider operating at a frequency and its first harmonic with unequal power dividers ratio was presented, where four groups of 1/6 wavelength transmission lines with different characteristic impedances are needed to match all ports.
Abstract: This letter presents a Wilkinson power divider operating at a frequency and its first harmonic with unequal power divider ratio. To obtain the unequal property, four groups of 1/6 wavelength transmission lines with different characteristic impedances are needed to match all ports. Theoretically, closed-form equations for the design are derived based on transmission line theory. Experimental results have indicated that all the features of this novel power divider can be fulfilled at f 0 and 2f 0 simultaneously.
TL;DR: Using W state, which is much more robust than GHZ state, the efficient quantum circuit is constructed to implement the QSDC by means of primitive operations in quantum computation.
Abstract: Utilizing W state, which is much more robust than GHZ state, we propose a protocol for three-party controlled quantum secure direct communication (QSDC). The feature of this protocol is that the sender encodes the secret message directly on a sequence of particle states and faithfully transmits them to an arbitrary one of two receivers without revealing any information to a potential eavesdropper. On the other hand, we construct the efficient quantum circuit to implement the QSDC by means of primitive operations in quantum computation.
TL;DR: It is found that noise and time delay may induce or enhance synchronization and change firing patterns of coupled neurons, and the idea and methods of nonlinear dynamics are of great significance in exploration of dynamic processes and physiological functions of nervous systems.
Abstract: Recent advances in the experimental and theoretical study of dynamics of neuronal electrical firing activities are reviewed. Firstly, some experimental phenomena of neuronal irregular firing patterns, especially chaotic and stochastic firing patterns, are presented, and practical nonlinear time analysis methods are introduced to distinguish deterministic and stochastic mechanism in time series. Secondly, the dynamics of electrical firing activities in a single neuron is concerned, namely, fast–slow dynamics analysis for classification and mechanism of various bursting patterns, one- or two-parameter bifurcation analysis for transitions of firing patterns, and stochastic dynamics of firing activities (stochastic and coherence resonances, integer multiple and other firing patterns induced by noise, etc.). Thirdly, different types of synchronization of coupled neurons with electrical and chemical synapses are discussed. As noise and time delay are inevitable in nervous systems, it is found that noise and time delay may induce or enhance synchronization and change firing patterns of coupled neurons. Noise-induced resonance and spatiotemporal patterns in coupled neuronal networks are also demonstrated. Finally, some prospects are presented for future research. In consequence, the idea and methods of nonlinear dynamics are of great significance in exploration of dynamic processes and physiological functions of nervous systems.
TL;DR: In this paper, a new scheme to generate an optical millimeter wave with octupling of the local oscillator via a nested LiNbO3 Mach-Zehnder modulator (MZM) is proposed and implemented by numerical simulation.
Abstract: What we believe to be a new scheme to generate an optical millimeter wave with octupling of the local oscillator via a nested LiNbO3 Mach-Zehnder modulator (MZM) is proposed and implemented by numerical simulation. Since the response frequency of the modulator and the local frequency are largely reduced, the bandwidth requirement of the transmitter to the optical and electrical components is reduced greatly. Then, the parameters of the nested modulator are analyzed theoretically, and we find that both the extinction ratio of the MZM and the phase imbalance between its two arms have influence on the performance of the generated optical millimeter wave.
25 Mar 2008
TL;DR: A novel approach to signal classification combining spectral correlation analysis and support vector machine (SVM) is introduced, which is more effective in the case of low SNR and limited training numbers.
Abstract: Spectrum sensing is one of the most challenging functions in cognitive radio system. Detection of the presence of signals and distinction of the type of signals in a particular frequency band are critical for cognitive radios to adapt to the radio environment. In this paper, a novel approach to signal classification combining spectral correlation analysis and support vector machine (SVM) is introduced. Four spectral coherence characteristic parameters are chosen via spectral correlation analysis. By utilizing a nonlinear SVM, a significant amount of calculation is performed offline, thus the computational complexity is reduced. Simulations indicate that the overall success rate is above 92.8% with data length of 1000 when SNR is equal to 4 dB. Compared to the existing methods including the classifiers based on binary decision tree (BDT) and multilayer linear perceptron network (MLPN), the proposed approach is more effective in the case of low SNR and limited training numbers.
TL;DR: An improved version of this protocol is given so that it can resist this attack of an eavesdropper utilizing a special property of GHZ states to elicit all or part of the transmitted secrets.
Abstract: We analyse the security of a quantum secure direct communication (QSDC) protocol and find that an eavesdropper can utilize a special property of GHZ states to elicit all or part of the transmitted secrets without being detected. The particular attack strategy is presented in detail. We give an improved version of this protocol so that it can resist this attack.
TL;DR: By using Hirota's bilinear method and symbolic computation, solutions for a variable-coefficient nonlinear Schrödinger equation are obtained theoretically and according to those solutions, the relevant properties and features of physical and optical interest are illustrated.
Abstract: By using Hirota's bilinear method and symbolic computation, solutions for a variable-coefficient nonlinear Schr\"odinger equation are obtained theoretically. It is found that the type of the solutions changes with the different choices of the group-velocity dispersion coefficient ${\ensuremath{\beta}}_{2}(z)$. According to those solutions, the relevant properties and features of physical and optical interest are illustrated. In addition, an effective technique for controlling the shape of the pulses is presented. The results of this paper will be valuable to the study of the future development of ultrahigh rate and long-distance optical communication systems.
TL;DR: In this article, the multisoliton solutions in terms of double Wronskian determinant are presented for a generalized variable-coefficient nonlinear Schrodinger equation, which appears in space and laboratory plasmas, arterial mechanics, fluid dynamics, optical communications and so on.
TL;DR: In this paper, the authors analyzed the relationships between variables in the TAM models and found that most of the relationships in the classical TAM are significant, but the stabilities of these relationships differ.
TL;DR: It is shown the first agent and the last agent can obtain all the secret without introducing any error in Zhang's et al. multiparty QSSCM scheme by a special attack with quantum teleportation.
TL;DR: A novel controlled quantum secure direct communication (QSDC) with quantum encryption under the supervision and help of the third side, the sender and the receiver can securely share the private quantum entanglement keys used to encrypt and decrypt the secret message.
Abstract: Utilizing a partially entangled GHZ state, we propose a novel controlled quantum secure direct communication (QSDC) with quantum encryption. Under the supervision and help of the third side, the sender and the receiver can securely share the private quantum entanglement keys used to encrypt and decrypt the secret message. According to the results of checking the eavesdropping on decoy photons, communicators can decide whether the quantum keys are reused in the next round. Not only will eavesdropping inevitably disturb the states of the decoy photons and be detected, but arbitrary transmission errors can also be corrected.
19 May 2008
TL;DR: Extensive simulations under different scenarios using OPNET verified that cmpSCTP can effectively enhance transmission efficiency and highlighted the superiority of cmp sCTP against the other SCTP's extension implementations under performance indexes such as throughput, handover latency, packet delay, and packet loss.
Abstract: This paper introduced cmpSCTP, a transport layer solution for concurrent multi-path transfer that modifies the standard Stream Control Transmission Protocol (SCTP). The cmpSCTP aims at exploiting SCTP's multi-homing capability by selecting several best paths among multiple available network interfaces to improve data transfer rate to the same multi-homed device. Through the use of path monitoring and packet allotment techniques, cmpSCTP tries to transmit given amount of packets at corresponding path as its ability. At the same time, cmpSCTP updates the transmission strategy based on the real-time information of all of paths. Using cmpSCTP's flexible path management capability, we may switch the flow between multiple paths automatically to realize seamless path handover. Extensive simulations under different scenarios using OPNET verified that cmpSCTP can effectively enhance transmission efficiency and highlighted the superiority of cmpSCTP against the other SCTP's extension implementations under performance indexes such as throughput, handover latency, packet delay, and packet loss.