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Journal of Beijing University of Posts and Telecommunications

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    • Several Hot Spots in the Field of Wireless Mobile Internet in 2005
    • SONG Dun-De
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 1-3. DOI:10.13190/jbupt.200502.1.songjd
    • Abstract ( 1176 )     HTML     　　
    • From the point of industry development, this paper proposes several hot spots in the research field of wireless mobile network. It is impossible to include all the problems in the filed of research, development and application. To the author's point of view, the wide band wireless network such as WiMAX, 3G, mobile the convergence of mobile and fixed network, CNGI will become the emphasis of the research, development and application and will achieve good results.
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    Papers

    • Performance Optimization of Internet Access in WCDMA
    • WANG Yue1, SONG Yong-Hua2, LIN Yong1, SHAN Xiu-Meng1
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 4-8. DOI:10.13190/jbupt.200502.4.wangy
    • Abstract ( 883 )     HTML     　　
    • This paper studies a proxybased scheme to improve the performance of Internet Access in WCDMA, and develops a queuing model for its analysis. By exploiting the relative delay tolerance of data service, new Scheme can reduce average response time while keeping high network utilization. Furthermore, analytical results show that the key factor affecting average response time is the number of parallel channels. Therefore we studied the channel configuration and performance optimization of such system, and developed an Adaptive Channel Adjustment Algorithm (ACAA) to support the system in a varying environment. Simulation results show that the ACAA can reduce average response time significantly on unknown and possible varying traffic conditions.
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    • The Mathematical Model of Designing Multi-Cavity FP Filter with Butterworth Filtering
    • QI Yongxing，CHEN Shuqiang，LIU Yuanan，GAO Zehua， QIAN Zongjue
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 16-20. DOI:10.13190/jbupt.200502.16.229
    • Abstract ( 1115 )     HTML     　　
    • Based on the power transmission and the properties of Butterworth filter, it achieves a class of FP filters with Butterworth filtering for multi-mirror FP filter. It constructs a mathematical model of several cavities FP filter to implement the Butterworth filtering, and attains their critical conditions. Further more, this paper foresees the mathematical relationships of parameters of mirrors in condition of more cavities, so simplifies the design of multi-cavity FP filters with high performance, and presents a practical method and solutions to design a FP filter with more cavities.
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    • A Revocable Anonymous ECash Scheme from Group Signatures
    • LI Mengdong1,YANG Yixian2,MA Chunguang2,CAI Manchun2
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 30-33. DOI:10.13190/jbupt.200502.30.limd
    • Abstract ( 1095 )     HTML     　　
    • A revocable anonymous ecash scheme from group signature added a one time tag was presented in this paper. In the scheme the bank acts as the group manager but just issues certificates, i.e. coins, to customers who become the group members when they withdraw coins from bank, and there is a trustee whose duty is revoking the anonymity of the coins. Ateniese et al's group signature scheme was used in the proposed scheme. Owing to the properties of the group signature scheme, the scheme can meet most demands of ecash schemes and have a high efficiency.
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    • The Evaluation of Poisson Based Packet Sampling Techniques
    • ZHANG Feng，LEI Zhenming
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 34-38. DOI:10.13190/jbupt.200502.34.zhangf
    • Abstract ( 972 )     HTML     　　
    • An event triggering packet sampling process based on Poisson distribution is proposed. Two types of Poisson sampling techniques in types of timer triggering and event triggering were evaluated on measurement precision in aspects of mean packet length, packet length distribution and whole traffic volume. It shows that event triggering Poisson sampling technique, with O (n) measurement overhead, performs better than time triggering one, and the sampling error of e Vent triggering Poisson sampling is only 1/2～1/3 of time triggering one. Event triggering Poisson sampling technique is more eligible for high speed network measurement environment to meet high precision requirement.
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    • An Improved User Authentication Scheme Using Smart Card
    • QIU Huimin,YANG Yixian,HU Zhengming
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 39-41. DOI:10.13190/jbupt.200502.39.qiuhm
    • Abstract ( 1043 )     HTML     　　
    • We present an improved remote user authentication scheme using smart card based on random number and time stamp. Our scheme has less computation and memory requirement, same communication load with above scheme. Furthermore, our scheme can avoid password guessing attack, replay attack, insider attack effectively, and realize user authentication indeed. More important, the previous generated password is secure even if the secret key of system is leaked or broken.
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    • A Novel TCP over Wireless Fading Channel and Its Steady State Throughput Model
    • YAO Ling，JI Hong，YUE Guangxin
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 42-45. DOI:10.13190/jbupt.200502.42.yaol
    • Abstract ( 1099 )     HTML     　　
    • We propose an improved wireless transport control protocol TCP_LD(TCP lose detection). Using bandwidth estimation, this scheme can distinguish the reason of packets errors, hence adopt appropriate congestion control mechanism. Based on the TCP throughput model of Padhye, an analytical model of TCP_LD steady state throughput is educed. The results show that our scheme is simple and effective for dealing with random packet loss, and can achieve significant throughput improvements without adversely affecting other concurrent TCP connections.
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    • Research on Self-Healing Routing Protocol in Ad hoc Networks
    • FENG Meiyu,CHENG Sheng,ZHANG Xu,DING Wei
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 46-49. DOI:10.13190/jbupt.200502.46.227
    • Abstract ( 1214 )     HTML     　　
    • A self-healing routing protocol based on Ad hoc on demand distance vector (SHAODV) is proposed to against node moving and communication breaking. In SHAODV, the connection admission control assures constructed route of long life. The link stability model can detect the stability of link for self-healing of unstable route locally. The selfhealed route can be optimized well by the optimization scheme. Simulation result shows that this model has low routing overhead and anti-breaking capability.
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    • Blind Channel Estimation Performance Analysis
    • SUN Weijun,ZOU Yongzhong,LI Daoben
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 50-53. DOI:10.13190/jbupt.200502.50.sunwj
    • Abstract ( 1268 )     HTML     　　
    • FIM(fisher information matrix) and CRB(cramer rao bound) for complex channel parameters estimation in Gaussian signal model and in deterministic signal model are analyzed separately in this paper. Furthermore, analysis of FIM and CRB for complex channel estimation is implemented when Gaussian noise power is assumed unknown. As for the singularity of FIM for blind channel estimation, CRBs under different constraints are analyzed. In the end, blind channel estimation algorithms are simulated and compared with CRB in deterministic signal model and in Gaussi an signal model separately.
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    • Mapping Human Hand Motion to Dexterous Robotic Hands
    • LIU Jie1，SUN Hanxu2，ZHANG Yuru3
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 54-58. DOI:10.13190/jbupt.200502.54.liuj
    • Abstract ( 970 )     HTML     　　
    • Describes the implementation of grasp planning for robotic dexterous hands. Human grasp strategy is learned through masterslave manipulation, A method of fingertip mapping is developed based on virtual fingers in cartesian space. Using the dataglove as human machine interface, joint angles are recorded and digit trajectories are computed using forward kinematics. The kinematics of movement of all digits is analyzed during grasp. The fingertip trajectories during grasp are recorded in Cartesian space. A virtual environment is developed to visualize the motion of the human hand and the robot hands. Visualization of the 3D workspace is accomplished. The mapping result is verified in the virtual environment, suggests that the mapping algorithm is correct.
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    • The Study of the Mapping of Call Concepts Between Parlay APIs and SIP
    • HAN Yanfeng,LU Meilian
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 58-62. DOI:10.13190/jbupt.200502.58.hanyf
    • Abstract ( 999 )     HTML     　　
    • The concepts related with call in parlay application programming interface(Parlay APIs) and session mitiation protocol(SIP) are analyzed and compared.A mapping relationship between the concepts of Call and Call Leg in Call Control service capability feature(SCF) of Parlay APIs and the concept of Dialog in SIP is given, including a mapping of related parameters of these concepts. Call concepts mapping models are proposed, in condition that SIP Server works at Proxy mode, B2BUA mode and 3rd Party controller mode. These models work as a precondition and base of mapping methods and parameters of Parlay APIs to operations and messages of SIP Server, perf orming a directing function for designing and developing Parlay Gateway in practical project of next generation of network(NGN).
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    • LSP's Delay and Congestion Based Distributed Adaptive
    • FENG Chunyan,ZHANG Chen,ZENG Zhimin,DING Wei
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 63-67. DOI:10.13190/jbupt.200502.63.226
    • Abstract ( 988 )     HTML     　　
    • A distributed adaptive traffic engineering algorithm HDCA（heuristic delay and congestion based algorithm of traffic engineering）for the MPLS（multiprotocol label switching）network is proposed in this paper. This algorithm is based on the LSP's (label switching path) delay and congestion. A mathematical model of the whole network traffic optimization was established,and HDCA algorithm was designed in terms of the mathematical model's hierarchie s. In this algorithm, tabu search and nonlinear changes of parameters were adopted to achieve excellent realtime performance, fast convergence speed, high stability, little running time and little network overhead. The simulation analysis shows that the HDCA algorithm fits to the traffic optimizing in the bone network.
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    • Capacity Comparison of CDMA and TDMA in Vector Broadcast Channel
    • ZHAO Shaogang，XIAO Zhengrong，WU Weiling
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 68-71. DOI:10.13190/jbupt.200502.68.zhaoshg
    • Abstract ( 1086 )     HTML     　　
    • The sumrate capacity of slow fading vector broadcast channel in code division multiple access (CDMA) system and time division multiple access (TDMA) system are thoroughly researched. The base station can only transmit to one user at a time in TDMA system. However, in CDMA system, the base station can send data to all the users at the same time. The TDMA system can achieves the sumrate capacity if the base station has only one transmit antenna, but it is suboptimal when the base station has multiple antennas. By a detailedanalysis, an upper bound of sumrate capacity in CDMA system and a lower bound of sumrate capacity in TDMA system are derived respectively. According to these two bounds, the sum rate capacity ratio of CDMA to TDMA at most can achieve the minimum of M and K. Here M is the number of the transmit antennas and K is the number of the users in this vector broadcast channel.
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    Reports

    • Design and Implementation of CAMEL Based SMS Control Function
    • HUANG Jun fei,LIAO Jianxin
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 72-75. DOI:10.13190/jbupt.200502.72.228
    • Abstract ( 1147 )     HTML     　　
    • A new short message service (SMS) control function proposed by europe telecommunication standardization institute (ETSI) in customized application for mobile nework enhanced logic (CAMEL) Phase 3 and CAMEL Phase 4 helps to solve the service trigger problems of the short message peer to peer (SMPP) based SMS control function solution used now. The design and implementation of the whole solution, SMS SCF call control model (SCSM) automaton, and new service independent block (SIBs) are presented in detail as the extension of service control point (SCP) funtions. The service capability of CAMEL based solution is explained by SMS prepaid service as example.
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    • An Improved Authentication Protocol of TETRA
    • LI Hui1,YANG Zhu2,YANG Yixian1
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 76-79. DOI:10.13190/jbupt.200502.76.lih
    • Abstract ( 916 )     HTML     　　
    • An authentication protocol for TETRA with authentication algorithm running in HLR instead of VLR is presented in this paper. The proposed protocol can effectively avoid the generation of an open attack for known text once the communication security between VLR and HLR can not be guaranteed.It is good for roaming between networks, meets the requirements for the independence of the authentication algorithm. The proposed protocol can improve the security of actual digital trunked system.
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    • The Tracking Range of CFO Tracking Algorithm Based on Signal Reconstruction for OFDM
    • ZHENG Laibo1,2,HU Jiandong1
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 80-83. DOI:10.13190/jbupt.200502.80.zhenglb
    • Abstract ( 1046 )     HTML     　　
    • The tracking range of a carrier frequency offset (CFO) tracking algorithm for orthogonal frequency division multiplexing (OFDM) systems based on timedomain received signal reconstruction was investigated deeply. It is found that the tracking range of this algorithm is not fixed. Analyses show the decision error is the main factor that affects the timedomain signal re construction accuracy and the tracking range, while the decision error is affected by subcarrier modulation scheme, subcarrier number, additive white Gaussin noise and channel estimate error, so dose the tracking range. We find that subcarrier modulation scheme and subcarrier number are main factors that affect the tracking range. The tracking range at different carrier numbers applying BPSK and 16QAM modulation scheme respectively on subcarriers are determined by simulation.
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    • A Simple Method to Calculate the Resonance Frequency
    • XIAN Jinlong,WANG Shengxuan,GAO Yougang
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 84-86. DOI:10.13190/jbupt.200502.84.xianjl
    • Abstract ( 937 )     HTML     　　
    • A simple semi analytical method is presented.It calculates the resonance frequency in asymmetric transverse electromagnetic cell by estimating the resonance frequencies of equal inhomogeneous transmission line with open circuit and short circuit at end. The moment method was used to calculate the capacitance of crosssection, then characteristic impedance along line was obtained. The numerical results were obtained in a table by solving the combined equation of transmission line impedance transfer equation and terminal input impedance expression in gas capacitance.
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    • An Iterative Algorithm of Signal Detection Based on CFAR
    • BAI Jian,YANG Yafei,XU Yinghui,YANG Yu,YANG Yixian
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 87-90. DOI:10.13190/jbupt.200502.87.baij
    • Abstract ( 994 )     HTML     　　
    • An iterative algorithm based on constant false alarm rate(CFAR) in signal detection fields is presented in this paper. This algorithm can estimate the statistical characteristic of intermediate frequency noise. It extracts signal from noise by analyzing statistical characteristic. It is easy to obtain the parameter of signal such as signal counts, bandwidth, carrier frequency after pure signal is extracted. This algorithm has been proved to be a simple and well self-adaptive method by MATLAB simulation.
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    • Research of H.323 Protocol over NAT Gateway
    • HOU Xizhu,MA Yue,CHEN Linan
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 91-94. DOI:10.13190/jbupt.200502.91.houxzh
    • Abstract ( 981 )     HTML     　　
    • Some efficient solutions for making H.323 call through network address translation(NAT) gateway are proposed in this paper. The H.323 protocol packets are unmodified from the source to the destination in endto end network. However, the port and IP address of these packets will be modified when they pass through the NAT gateway. The modified packets address cannot match the calling address in the H.323 protocol packets. This will result the H.323 call abnormal. We present some efficient methods to solve this problem by extending the ALG (application layer gateway) model.
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    • Extending Parlay API in Security domain
    • LI Kai，YANG Fangchun
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 95-100. DOI:10.13190/jbupt.200502.95.lik
    • Abstract ( 984 )     HTML     　　
    • A new service develop interface NGSSAPI(next generation security service appacation programming interface) is proposed in this paper. It is a standard, opened, scalable and user oriented interface according to the open service access(OSA). It can accelerate the new service developing process through supplying NGN's security service feature set to service developer. It can be used to create security service alone, or cooperate with Parlay's other service interface to develop more complicated service. This interface will prompt NGN's security development greatly.
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    • A Practical OneTimePadLike Block Cipher Scheme
    • ZHANG Yuan，FENG Dengguo
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 101-104. DOI:10.13190/jbupt.200502.101.zhangya
    • Abstract ( 1151 )     HTML     　　
    • A concrete symmetric cipher scheme SCB, which can be easily implemented in both software and hardware, is presented. It combines the superiorities of both block and stream ciphers. From the viewpoint of one single block encryption, SCB is a kind of reiterative block cipher. However, the attackers will have to face with a onetimepad like cipher scheme if they do not carry through an exhaustive key search attack.
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    • A Novel OFDM Timing Synchronization Algorithm in Multipath Fading Channel
    • ZHANG Jie，CAI Peng，ZHANG Ping
    • Journal of Beijing University of Posts and Telecommunications. 2005, 28(2): 105-108. DOI:10.13190/jbupt.200502.105.zhangj
    • Abstract ( 1069 )     HTML     　　
    • This paper proposes a novel training symbolbased orthogonal fraquency division multiplexing (OFDM) timing synchronization algorithm. This algorithm analyzes the problem of discrete fourier transform (DFT) window timing with error away from cyclic prefix in multipath fading channel where the first path is not the strongest one. In this case the intersymbol interference (ISI) is resulted by the multipaths arriving at the receiver ahead of the strongest path. This new timing algorithm can easily separate different paths and find the strongest one. Considering the fact that the duration of the first path in deep fading will not last for a long time, Alpha filter is applied in timing metric to achieve averaging effect. Moreover search window and threshold are introduced to easily find out the first path at any situation with low complexity and high timing correct probability. This novel timing algorithm is very suitable for wireless multipath environments.
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