Current Issue

• • 2003, Vol. 26 No. 1 Published date:28 January 2004 Last issue Next issue

  SUMMARIZATION

  • Key Technologies Towards Next Generation of Network
  • YANG Fang-chun
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 1-8.
  • Abstract ( 336 )     HTML     　　
  • Next generation of network(NGN) is similar to many aspects of intelligent network(IN) principles, but it works better than IN due to different implementation technologies. Through comparisons between the architectures and goals of NGN and IN, five major drawbacks appeared in current IN technology are analyzed. Thenseveral key technologies on open API, service generation methodology and network evolution that need to be concerned and further investigated for NGN are proposed, especially regarding how to inherit the invested IN to build NGN architecture.
  • References | Supplementary Material | Related Articles

  PAPERS

  • Performance Analysis of 2D-Rake Receiver in a Nakagami Fading Channel with Arbitrary Parameters
  • LU Jing-yang, XUE Qiang, WU Wei-ling
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 9-13.
  • Abstract ( 224 )     HTML     　　
  • Based on beam-forming and conventional Rake technology, 2D-Rake receiver is composed of antennas array, time-delay, beamforming, coherent demodulation,despread, and maximum rate combing (MRC). In Nakagami fading channel with arbitrary parameter, the bit error rate (BER) of 2D-Rake receiver is investigated for single cell coherent DS-CDMA system. Theoretic analysis and numerical results indicate that 2D-Rake receiver can achieve the space-temporal gain from independent multipath component, and its BER get an advantage over the conventionalRake receivers or the multi-antenna receiver. The number of users supported bythe system is also increased in a great deal.
  • References | Supplementary Material | Related Articles

  • A Segmentation Method of Cursive Handwritten Digit String Based on Limited Dynamic Programming
  • LIU Gang, WEI Feng, WU Ming, ZHANG Hong-gang, GUO Jun
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 14-18.
  • Abstract ( 271 )     HTML     　　
  • We analyze the difficulty of segmenting cursive handwriting digit string, propose a segmentation method based on limited dynamic programming, and research intothe searching space, searching method, and cost function during segmentation. We applied this method to segment handwriting count that is cursive and crabbed,and get satisfactory results.
  • References | Supplementary Material | Related Articles

  • A SE-CMA Based Adaptive Multiuser Detection
  • XU E Qiang ,　JIAN G Xiao-bing ,　WU Wei-ling
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 19-22.
  • Abstract ( 317 )     HTML     　　
  • A multiuser detection structure is proposed which can be used in multi-path channel. This algorithm is based on SE-CMA(sign error constant modulo algorithm).Experiences and simulations show that the approach converges fast and has a goodperformance, so it is a good adaptive multiuser detection.
  • References | Supplementary Material | Related Articles

  • The Impact of Channel Correlation Variation on the Performance of Multiple Input-Multiple Output Systems
  • FU Jing-xing, 　YANG Da-cheng, 　CHANG Yong-y u
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 23-26.
  • Abstract ( 242 )     HTML     　　
  • The performance of multiple input-multiple output (MIMO) system with channel correlation fluctuation is studied. The simulation results indicate that the performance of MIMO systems in the flat fading environment is primarily relied on correlation variation caused by the different displacements of the antennas and thedifferent distributions of local scattering.
  • References | Supplementary Material | Related Articles

  • Simulation Analysis of Two Max C/I Scheduling Algorithms Applied to HSDPA
  • CUI Chun-feng, DU Lei, JI Yang, ZHANG Ping
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 27-31.
  • Abstract ( 278 )     HTML     　　
  • HSDPA is the solution to the high speed downlink packet services in UMTS. The max C/I scheduling is one of its scheduling algorithms. Two different scheduling algorithms, thorough max C/I and retransmission priority max C/I, were simulated, andthe relation curve of the maximum number of retransmission and FER was obtained. When the maximum number of retransmission is low the performance of thorough max C/I is better than retransmission priority max C/I, and when maximum number of retransmissionis high the performance of retransmission priority max C/I is better than thorough max C/I. The cause of the simulation results was also analyzed.
  • References | Supplementary Material | Related Articles

  • A New Wavelength Assignment Algorithm in WDM Optical Network
  • CHENG Xiao-fei, 　JIN Wen-yan, 　WAN G Yong, 　GU Wan-yi
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 32-36.
  • Abstract ( 275 )     HTML     　　
  • A new wavelength assignment in multi-wavelength, fixed routing WDM network is presented. Performance of different algorithms are analyzed and simulated in ring, mesh and CERNET_{_}like network topologies. Blocking probabilities are evaluated. Simulation results show that the new wavelength assignment reduces the blocking probability and improves the network performances.
  • References | Supplementary Material | Related Articles

  • A Distributed QoS Unicast Routing Algorithm Based on Delay Constraint
  • KONG Ling-shan, DING Wei
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 37-40.
  • Abstract ( 244 )     HTML     　　
  • A distributed QoS heuristic algorithm based on unicast routing by applying the concept of the cost and delay-bounded is proposed. This algorithm can generate therouting path that is subject to a sub-optimal network cost under the conditionof delay constraint, with a relatively low message complexity. And it needs no information stored in media router during the path setup. Simulations have been done to show the efficiency of the algorithm proposed.
  • References | Supplementary Material | Related Articles

  • Analysis of Interpolation Algorithms in Piloted Channel Estimation for OFDM Systems
  • KUANG Yu-jun, YUE Guang-xin
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 41-45.
  • Abstract ( 298 )     HTML     　　
  • In wired and w ireless OFDM systems, the channel response is obtained by interpolat ion of a piloted coar se est imat ion. Several interpolat ion algo rithms for PSAM OFDM systems ar e discussed; perfo rmance of an FFT -based inter polat ion is evaluated. Finally, some sug gest ions ar e pro posed.
  • References | Supplementary Material | Related Articles

  • Performance Analysis for CPICH Acquisition in WCDMA
  • N IU Kai,　WU Wei-ling
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 46-49.
  • Abstract ( 342 )     HTML     　　
  • The acquisition of CPICH (common pilot channel) provides the primary scramblingcode of one base station which is the third step of cell search algorithm in WCDMA systems. By modeling the acquisition process, this paper gives the theoretical formula for the detection probability, missing probability and alarm probability in the case of MAI under the single path Rician fading channel. What's more,we analyze the threshold setting rules and detection probability curve.
  • References | Supplementary Material | Related Articles

  • Scalable Reliable Multicast Protocal Using Active FEC
  • YANG Jian, WANG Wen-dong, FAN Rui, CHENG Shi-duan
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 50-54.
  • Abstract ( 270 )     HTML     　　
  • The problem of localizing the repair packets when packets are lost during multicast is studied. A new protocol which combines the advantage of FEC and active network technology is presented. In this proposal, repair packets can only reach the receivers that need them and thus the consumption of network bandwidth and receivers' computing capability is reduced. The overhead of this proposal is alsovery small.
  • References | Supplementary Material | Related Articles

  REPORTS

  • Architecture of Network Management System for Multi-Technology Network
  • ZHAN Zhi-qiang, MENG Luo-ming, QIU Xue-song
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 55-59.
  • Abstract ( 279 )     HTML     　　
  • From the netw ork manag ement v iew , relat ionships betw een dif ferent dedicated netw or ks in mult i-technolo gy netw or k are analy zed. A conclusion is given, w hich relationships of netw o rk manag ement systems of dif ferent dedicated netw orks are designed as associated relat io nships is pr efer able. Based on relationships discussed, ar chitecture of netw ork management sy stem for mul titechnolo gy netwo rk is pr esented. T he system const ruct ion and the management interface in the ar chitecture are discussed. Some pivotal implementing technologies of the netw ork manag ement system for mult i-technolo gy netw ork are int roduced.
  • References | Supplementary Material | Related Articles

  • The Performance Analysis of a Receiver with CombingMultistage Parallel Interference Cancellation and Antenna Array
  • LIANG Shuang-chun ,　WEI Hui-min ,　WU Wei-ling
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 60-63.
  • Abstract ( 266 )     HTML     　　
  • A new CDMA receiver that combining multistage parallel interference cancellationas an multiuser detection method and antenna array is given. According to MMSEcriterion, the weights can be found by adaptive algorithms, that is used to combing the soft-decision output user data after multistage parallel interference cancellation processing and antenna array receiving.The computer simulation result is given, it explains the good performance of this receiver to resist multipath effect.
  • References | Supplementary Material | Related Articles

  • A Novel Method of Inverting Signal Spectrum for Software Radio System
  • ZHANG Yu-liang, 　WU Wei-ling, 　TIAN Bao-yu
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 64-68.
  • Abstract ( 384 )     HTML     　　
  • While the direct band-pass sampling method for multiple discontinuous narrow-band radio signals can ease up the A/D bottleneck in a software radio system, thespectrum of some of signal may be inverted. The impact of the inverseplacement of spectrum for signals with different modulation modes is analyzed,then the method to invert radio signal spectrum is given. An implementation method with low computation complexity(number of computation needed per unit time) is given based on multi-rate digital signal processing theory.
  • References | Supplementary Material | Related Articles

  • A Rapid DOA Estimating Algorithm
  • ZHAI Ming-yue, LIU Yuan-an
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 69-72.
  • Abstract ( 253 )     HTML     　　
  • Based o n the property of coherent signal source, a ra pid DO A estimating alg orithm emplo ying FFT has been proposed. Compa rison wi th MU SIC algo ri thm is perfo rmed by computer simula tion. The result has show ed tha t the proposed alg orithm i s feasible, especially in the low SN R env iro nment or in real time si tuatio ns.
  • References | Supplementary Material | Related Articles

  • The Analysis of Fiber Nonlinear Effects
  • WANG Jian-quan, GU Wan-yi
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 73-77.
  • Abstract ( 275 )     HTML     　　
  • A synthet ical equat ion about o pt ical fiber nonlinear effect s in WDMt ransmission system is propo sed. A supplementary split-step Fourier metho d to so lve the equat ion is proposed too. T he equat io n and the solving method can be used to analyze and compar e among f iber nonlinear effect s, w hile it avails to simulate and analyze performance o f WDM t ransmission system.
  • References | Supplementary Material | Related Articles

  • A New CMA-Based Blind Adaptive Multiuser Detection
  • ZHANG Hao-liang, DUAN Lian, XUE Qiang, WU Wei-ling
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 78-81.
  • Abstract ( 281 )     HTML     　　
  • A new difference-based CMA is proposed. Simulation indicates thatin all test situations, e.g. Additive white gaussian noise (AWGN) channel and multipath environment, this algorithm is very robust for any value of starting vectors and modulus, and has some practical value.
  • References | Supplementary Material | Related Articles

  • Comparison of the Soft Output Algorithms for High Order Modulation
  • HE Yan-feng, YANG Hong-wen, GUO Wen-bin
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 82-85.
  • Abstract ( 412 )     HTML     　　
  • Since soft input is necessary for Turbo decoder, thedemodulator located before the decoder should offer the soft output. The commonly used soft output demodulating-algorithms, log-MAP and its approximation max-log-MAP are described. The simulation showed that the performance differenceof the two algorithms for the same decoding error rate is within 0.1 dB , butthe complexity of log-MAP is much higher. The combination of max-log-MAP demodulator and log-MAP Turbo decoder can achieve the almost optimal performance with reduced complexity of hardware implementation.
  • References | Supplementary Material | Related Articles

  • A New 2D Rake Receiver Based on Sampling Matrix and RLS-Kalman Algorithm
  • Y AN Zhi-gang,　WU Wei-ling
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 86-90.
  • Abstract ( 298 )     HTML     　　
  • A novel 2D Rake receiver based o n sampling mat rix and RLS-Kalman alg orithm w as proposed in the li tera ture. In ev ery i tera tion step, the input data of 2D Rake i s a mat rix , which w ere formed by N ( spread facto r) samplings. The ada ptiv e alg o ri thm used in 2D Rake comes f rom the time-v arying system t racking idea, and w as modified to acco rd w ith input mat rix. The new 2D Rake is propi tio us to integ rate wi th multiuser detectio n techno logy because the st ructure of spread sig nal w as reserv ed in 2D Rake output.
  • References | Supplementary Material | Related Articles

  • The Synchronization Principle and Realization Techniqueof Base Station Subsystem in CDMA
  • GAO Wen-chang,LUO Hong,ZHAI Wen-jun,SUN Yan,YANG Qin
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 91-94.
  • Abstract ( 279 )     HTML     　　
  • By discussing and comparing the principle and realization technology for two synchronous method (master-slave synchronous and pseudo-synchronous) between CDMAdigital PLMN and PSTN, it makes a conclusion that by adopting high quality reference clock from GPS, pseudo-synchronous method can coordinate the two reference clocks of BSS and realize transport synchronization without adding any cost. This method can simplify BSS design.
  • References | Supplementary Material | Related Articles

  • A Novel Hybrid ARQ Scheme for OFDM Systems
  • XING Xiao-gang, YANG Hong-wen, GUO Wen-bin
  • Journal of Beijing University of Posts and Telecommunications. 2003, 26(1): 95-98.
  • Abstract ( 256 )     HTML     　　
  • A novel Hybrid ARQ scheme for orthogonal frequency division multiplexing (OFDM)systems is proposed. The scheme exploits the property of high level modulation that the performance of different bits mapped to the same modulation symbol is different, and the property of the multi-path channel that the fading between anypair of OFDM subcarriers is independent, provided that the frequency interval is wider than channel's coherent bandwidth. In the retransmission of one data packet, the bit level interleaving mode is changed,so that the transmission orderis changed, and the packet is maximum ratio combined at the bit level.
  • References | Supplementary Material | Related Articles