Cheng Weiqing，Hu Yangyang, Yin Qiaofeng, Chen Jiajia
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60237-1
Abstract ( 966 ) PDF (365 KB)( 1047 )
To understand website complexity deeply, a web page complexity measurement system is developed. The system measures the complexity of a web page at two levels: transport-level and content-level, using a packet trace-based approach rather than server or client logs. Packet traces surpass others in the amount of information contained. Quantitative analyses show that different categories of web pages have different complexity characteristics. Experimental results show that a news web page usually loads much more elements at more accessing levels from much more web servers within diverse administrative domains over much more concurrent transmission control protocol (TCP) flows. About more than half of education pages each only involve a few logical servers, where most of elements of a web page are fetched only from one or two logical servers. The number of content types for web game traffic after login is usually least. The system can help web page designers to design more efficient web pages, and help researchers or Internet users to know communication details.
Zhang Yongtang， Fan Bo
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60238-3
Abstract ( 804 ) PDF (3050 KB)( 331 )
Layer 2 network technology is extending beyond its traditional local area implementation and finding wider acceptance in provider’s metropolitan area networks and large-scale cloud data center networks. This is mainly due to its plug-and-play capability and native mobility support. Many efforts have been put to increase the bisection bandwidth in layer 2 network, which has been constrained by the spanning tree protocol (STP) that layer 2 network uses for preventing looping. The recent trend is to incorporate layer 3’s routing approach into layer 2 network so that multiple paths can be used for forwarding traffic between any source-destination (S-D) node pair. Equal cost multipath (ECMP) is one such example. However, ECMP may still be limited in generating multiple paths due to its shortest path (lowest cost) requirement. In this paper, we consider a non-shortest-path routing approach, called equal preference multipath (EPMP) based on ordered semi group theory, which can generate more paths than ECMP. In EPMP routing, all the paths with different traditionally-defined costs, such as hops, bandwidth, etc., can be determined equally now and thus they become equal candidate paths. By the comparative tests with ECMP, EPMP routing not only generates more paths, provides 15% higher bisection bandwidth, but also identifies bottleneck links in a hierarchical network when different traffic patterns are applied. EPMP is more flexible in controlling the number and length of multipath generation. Simulation results indicate the effectiveness of the proposed algorithm. It is a good reference for non-blocking running of big datacenter networks.
Yang Jingmin1, Zhang Wenjie1, Zou Fumin2
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60239-5
Abstract ( 851 ) PDF (1219 KB)( 327 )
To understand the utilizability of TV white spaces (TVWS), a comprehensive overview of the outdoor and indoor network design over TVWS is given. The related challenges are analyzed. The potential approaches to overcoming these challenges are discussed. The open research issues are investigated. The result shows that: in the indoor scenario, the white space ratio is on average 18.4% higher than that in the outdoor scenario, which corresponds to 7.7 vacant TV channels. Both network design includes 7 key components: TV spectrum identification, access point (AP) discovery, AP association, spectrum allocation, band width adaptation, interface control and disruption handling. Due to building penetration loss, the indoor TVWS identification and AP placement should be carefully considered in the indoor scenario.
Shi Li1,Nie Min1, Yang Guang1,2, Pei Changxing3
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60240-1
Abstract ( 792 ) PDF (1083 KB)( 292 )
In order to study the relationship between the non-spherical atmospheric charged particles and satellite-ground quantum links attenuation. The relationship among the particle concentration, equivalent radius, charge density of the charged particle, the attenuation coefficient and entanglement of the satellite-ground quantum link can be established first according to the extinction cross section and spectral distribution function of the non-spherical atmospheric charged particles. The quantitative relationship between atmospheric visibility and communication fidelity of satellite-ground quantum link were analyzed then. Simulation results show that the ellipsoid, Chebyshev atmospheric charged particle influences on attenuation of the satellite-ground quantum link increase progressively. When the equivalent particle radius is 0.2 μm and the particle concentration is 50 μg/m3, the attenuation coefficient and entanglement of the satellite-ground quantum link is 9.21 dB/km, 11.46 dB/km and 0.453, 0.421 respectively; When the atmospheric visibility reduces from 8 km to 2 km, the communication fidelity of satellite-ground quantum link decreases from 0.52 to 0.08. It is shown that the non-spherical atmospheric charged particles and atmospheric visibility influence greatly on the performance of the satellite-ground quantum link communication system. Therefore, it is necessary to adjust the parameters of the quantum-satellite communication system according to the visibility values of the atmosphere and the shapes of the charged particles in the atmosphere to improve reliability of the satellite-ground quantum link.
Wu Zhijun,Cui Zihan, Wang Caiyun, Lei Jin
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60241-3
Abstract ( 783 ) PDF (1159 KB)( 257 )
Access control scheme is proposed for System Wide Information Management (SWIM) to address the problem of attribute revocation in practical applications. Based on the attribute based encryption (ABE), this scheme introduces the proxy re-encryption mechanism and key encrypting key (KEK) tree to realize fine-grained access control with attribute revocation. This paper defines the attributes according to the status quo of civil aviation. Compared with some other schemes proposed before, this scheme not only shortens the length of ciphertext (CT) and private key but also improves the efficiency of encryption and decryption. The scheme can resist collusion attacks and ensure the security of data in SWIM.
Ma Xin,Jing Xiaojun
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60242-5
Abstract ( 773 ) PDF (1559 KB)( 256 )
Gabor features have been shown to be effective for palm vein recognition. This paper presents a novel feature representation method, implementing the fusion of local Gabor histograms (FLGH), in order to improve the accuracy of palm vein recognition systems. A new local descriptor called local Gabor principal differences patterns (LGPDP) encodes the Gabor magnitude using the local maximum difference (LMD) operator. The corresponding Gabor phase patterns are encoded by local Gabor exclusive OR (XOR) patterns (LGXP). Fisher’s linear discriminant (FLD) method is then implemented to reduce the dimensionality of the feature representation. Low-dimensional Gabor magnitude and phase feature vectors are finally fused to enhance accuracy. Experimental results from Institute of Automation, Chinese Academy of sciences (CASIA) database show that the proposed FLGH method achieves better performance by utilizing score-level fusion. The equal error rate (EER) is 0.08%, which outperforms other conventional palm vein recognition methods (EER range from 2.87% to 0.16%), e.g., the Laplacian palm, minutiae feature, Hessian phase, Eigenvein, local invariant features, mutual foreground local binary patterns (LBP), and multi-sampling feature fusion methods.
Zheng Fengming, Li Shufang, Guo Zhimin, Wu Bo, Tian Shiming, Pan Mi
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60243-7
Abstract ( 997 ) PDF (1004 KB)( 580 )
Anomaly detection in smart grid is critical to enhance the reliability of power systems. Excessive manpower has to be involved in analyzing the measurement data collected from intelligent motoring devices while performance of anomaly detection is still not satisfactory. This is mainly because the inherent spatio-temporality and multi-dimensionality of the measurement data cannot be easily captured. In this paper, we propose an anomaly detection model based on encoder-decoder framework with recurrent neural network (RNN). In the model, an input time series is reconstructed and an anomaly can be detected by an unexpected high reconstruction error. Both Manhattan distance and the edit distance are used to evaluate the difference between an input time series and its reconstructed one. Finally, we validate the proposed model by using power demand data from University of California, Riverside (UCR) time series classification archive and IEEE 39 bus system simulation data. Results from the analysis demonstrate that the proposed encoder-decoder framework is able to successfully capture anomalies with a precision higher than 95%.
Zhou Qianneng, Zhu Ling, Li Hongjuan, Lin Jinzhao, Wang Liangcai, Luo W
The Journal of China Universities of Posts and Telecommunications, 2017, 24 (6). doi： 10.1016/S1005-8885(17)60244-9
Abstract ( 809 ) PDF (1086 KB)( 317 )
Novel high power supply rejection ratio (PSRR) high-order temperature-compensated subthreshold metal-oxide- semiconductor (MOS) bandgap reference (BGR) is proposed in Semiconductor Manufacturing International Corporation (SMIC) 0.13 μm complementary MOS (CMOS) process. By adopting subthreshold MOS field-effect transistors (MOSFETs) and the piecewise-curvature temperature-compensated technique, the output reference voltage’s temperature performance of the subthreshold MOS BGR is effectively improved. The subthreshold MOS BGR achieves high PSRR performance by adopting the technique of pre-regulator. Simulation results show that the temperature coefficient (TC) of the subthreshold MOS BGR is 1.38× /°C when temperature is changed from 40 °C to 125 °C with a power supply voltage of 1.2 V. The subthreshold MOS BGR achieves the PSRR of 104.54 dB, 104.54 dB, 104.5 dB, 101.82 dB and 79.92 dB at 10 Hz, 100 Hz, 1 kHz, 10 kHz and 100 kHz respectively.