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Journal of Beijing University of Posts and Telecommunications

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  • SUMMARIZATION

    • Routing Algorithms in Mobile Ad hoc Networks
    • LIU Yuan-an, TANG Bi-hua, HU Yue-mei
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 1-7.
    • Abstract ( 278 )     HTML     　　
    • The fast development of Ad hoc networks in the past few years made it as a key part of the next generation network. This paper introduces various existing routing algorithms including multipath routing algorithmsin Ad hoc networks, such as the table-driven routing protocols and source-initiated on-demand routing algorithms, especially the source-initiated on-demandrouting. For the source-initiated on-demand routing, we analyze the time complexity, communication complexity, etc. Then we further do the investigation on QoS of Ad hoc networks, not only referring to the delay and the bandwidth, but also the stability of the link and routing, also including the power consumption.In the last part, we further introduce our research results on QoS routing algorithms.
    • References | Supplementary Material | Related Articles

    PAPERS

    • NGN: A Top-Down Vision
    • ZHONG Yi-xin
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 8-13.
    • Abstract ( 297 )     HTML     　　
    • The worldwide debate on Next Generation Network, NGNin brief, has been carried on for a couple of years and the major standardization organizations in the world like ITU-T and IETF have proposed number of recommendations in this regard in the past years. There have not yet been satisfactorycommon understandings achieved so far, however. In view of the strategic naturethat NGN possesses, it seems hardly possible to solve the problems if the debate is going on with a bottom-up approach. An attempt is therefore made in the paper to take a new vision, a top-down vision, for investigating the NGN issues,thus providing the Large-scaled Information Network System (LINS) as a candidate of the NGN solution to attract more concerns.
    • References | Supplementary Material | Related Articles
    • An Kind of (t, n)Threshold Secret Sharing
      Based on Lagrange Insert Value
    • DAI Yuan-Jun, MA Chun-Guang, YANG Yi-Xian
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 24-28.
    • Abstract ( 260 )     HTML     　　
    • By means of the intractability of Ellipse Curve Discrete Logarithm Problem (ECDLP), a (t, n) secret sharing threshold scheme based on Lagrange insert value is presented. Every participant is able to verify the share that hereceives and those other participants show, but the secret share isn't given away. This scheme can prevent adversaries from getting the shares and the participants cheating each other efficiently. The problem of renew shared secret, dynamic sub-secret allocation are properly treated in this scheme. An example of the scheme using the small number is given. The security of the scheme is analyzed in thefinal.
    • References | Supplementary Material | Related Articles
    • An AMC/HARQ Scheme Based on ACK Feedback
    • YANG Hong-wen, XIAO Xuan, GUO Wen-bin, YANG Da-cheng
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 29-33.
    • Abstract ( 240 )     HTML     　　
    • A novel adaptive AMC/HARQ scheme is proposed. The scheme makes use of ACK/NAK information to control the modulation/coding format, hence the C/I information feedback is no more required. The convergence and throughput performance in staticchannel is analyzed and the simulated performance for time varying fading channel is shown. The performance of the proposed scheme is comparable to the conventional C/I based AMC/HARQ where the C/I information known to the transmitter is not accurate. With the proposed scheme, the system design can be simplified and the reverse link capacity can be saved in case where the reverse link capacity isscarce.
    • References | Supplementary Material | Related Articles
    • Analysis of Performance of LDPC on Rician-Fading Channels
    • LIN Jia-ru, WU Wei-ling
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 48-53.
    • Abstract ( 248 )     HTML     　　
    • This paper analyzes and simulates the performance of low density parity check codes (LDPC) on Rician fading channels, and modifies BP decoding algorithm, provesthe symmetry and shows the stability conditions of the channels calculates theShannon limit of Rician channels. Using Visual C++ programming to simulate the performance, the result indicates that when code length N=3 072, coderate R=1/3, the distance with Shannon limit is about 2 dB. The performance of LDPC is also very effective on all kind of channels, including Rician channels.
    • References | Supplementary Material | Related Articles
    • Bandwidth Enhancement Techniques for Dif ferent Shapes of Single-Patch Single-Layer Microstrip Patch Antenna
    • ABDALLAH A. S. ,MO HAMM ED Y. E. ,LIU Y. A.
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 54-60.
    • Abstract ( 294 )     HTML     　　
    • Several techniques of ba ndw idth enhancement a re ado pted in this paper fo r dif ferent shapes o f single-lay er single-pa tch antenna. They are mainly: theprobe-fed square patch antenna with sho rting pins, a nd the pro be-fed rectang ular patch antenna wi th a pai r o f wide slit s ( E-sha ped pa tch ) . The a nalyses w ere ca rried out using method o f moments sof tw are packag e. It i s show n that the pro be-fesquare patch a ntenna can be made resonate a t th ree dif ferent f requencies o f 1. 83 GHz, 2. 16 GHz and 2. 74 GHz respectiv ely w ith a peak gain o f 9. 4 dB. The Eshaped pa tch is designed to resonate at tw o di fferent f requencies o f 2. 13 G Hz and 2. 5 GHz wi th ov erall impeda nce bandwidth of about 33. 33% ( return loss≤ - 10dB) wi th respect to a center f requency of 2. 4 GHz. The peak gain i s about 9. 25dB.
    • References | Supplementary Material | Related Articles
    • MPEG4 Video Traffic Model
    • LI Zheng, WU Wei-ling
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 66-71.
    • Abstract ( 240 )     HTML     　　
    • In this paper, two popular approaches are implemented and compared in modeling MPEG4 video traffic. One is the Markov modulated self-similar process model based on decomposition according to Scene complexity, the other is the structurallymodulated self-similar process. At the same time, the way to generate new wavelet coefficients in [2] has been improved in order to get more accurate second-order character.
    • References | Supplementary Material | Related Articles

    REPORTS

    • A Novel Channel Coding and Modulation Scheme Adopted
      in the Digital Television Terrestrial Broadcasting
    • HAN Meng, MEN Ai-dong, PAN Chang-yong, YANG Zhi-xing
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 72-73.
    • Abstract ( 257 )     HTML     　　
    • A new channel coding and modulation scheme adopted in Digital Television Terrestrial Broadcasting (DTTB) is presented, in which multilevel Block Product Code (BPC) is for the first time introduced to replace the serially concatenated codingarchitectures to improve spectrum efficiency and a multi-resolution 64QAM constellation is used for hierarchical modulation to offer three tiers of services within one DTTB channel. In the receiver, an iterative turbo decoding algorithm based on MAX-LOG-MAP criterion is adopted to achieve robust reception. Simulation shows that the bit SNR of High Priority stream is about 7 dB at the Thresholdof Visibility, which is competent for services requiring high reliability. TheMedium and Low Priority streams can support fixed outdoor reception.
    • References | Supplementary Material | Related Articles
    • DNA Computing and Data Encryption Standards
    • YOU Lin, WEN Qiao-yan, YANG Yi-xian
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 77-83.
    • Abstract ( 258 )     HTML     　　
    • DNA computing is just a series of bio-operations on DNA strands by some specialenzymes. After the bio-operations on DNA strands and the Adleman's DNA algorithm for solving Directed Hamiltonian Path Problem were introduced, we discuss indetail the Boneh's method for attacking DES by DNA computing and point out the time cost can be reduced about a half by making use of a complementarity of DES algorithm. Finally, the possibility of attacking AES by a method similar to Boneh's is analyzed.
    • References | Supplementary Material | Related Articles
    • An Agent-Based VHE System in NGN
    • HU Xiao-juan, SU Sen, GUO Le-shen, CHEN Jun-liang
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 93-97.
    • Abstract ( 255 )     HTML     　　
    • the VHE is an important concept of 3G. In this paper, an agent-based VHE service platform is proposed according to this concept. For the first time, the VHE service platform is implemented by a group of finely granular agents. Furthermore,some policies are proposed to optimize the implementation of VHE service platform.
    • References | Supplementary Material | Related Articles
    • Measurements of In-Building Penetration Loss at 2. 4 GHz
    • MO HAMM ED Y. E. ,　ABDALLA H A. S. ,　LIU Y. A.
    • Journal of Beijing University of Posts and Telecommunications. 2004, 27(2): 98-102.
    • Abstract ( 259 )     HTML     　　
    • The potential implementatio n o f wi reless radio local area netw orks and perso nal communication services inside building requi re a tho roug h understanding o f sig nal pro paga tion in a building. In thi s paper an in-building penet ra tion lo ssmeasurement s at 2. 4 GHz ( the ISM band) hav e been presented fo r materials used in indo or env iro nment s. To o btain the data, measurement s w ere perfo rmed a t 160 MHz bandw idth centered in 2. 4 GHz using v ecto r netw ork ana lyzer. These measurements may aid in the dev elopment o f future in-building w ireless netw o rks in this band.
    • References | Supplementary Material | Related Articles

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