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Analysis and Simulation for Capacity of Time division-Synchronous code division multiple access System

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Journal of Systems Engineering and Electronics 2002年第4期13卷 91-97页

作者： Sun Chengjun, Zhang Zhongzhao, Ba Yong2 & Cao Pengzhi (Communication Research ("enter, Harbin Institute of Technology, Harbin 150001, P. R. China Department of Electronic Engineering, Tsinghua University, Beijing 100084, P. R. China Research and Development division, Shanghai Bell Company Limited, Shanghai 200092, P. R. China) Communication Research Center Harbin Institute of Technology Harbin 150001 P. R. China Department ot Electronic Engineering Isinghua University Beijing 100084 P. R. China Research and Development division Shanghai Bell Company Lirmted Shanghai 200092 P. R. China

Capcity both in uplink and downlink of TD-SCDMA (time division-synchronous code division multiple access) system is studied in a multi-cell environment. The theoretical expressions of the mean of intercell interference in uplink and the mean of sum of power allocation in downlink are given, by which uplink and downlink capacity is analyzed. Furthermore, we give the simulation models for both uplink and downlink capacity. The results from theoretical analysis and simulation fit very well. In the end, the maximum number of users that TD-SCDMA system can serve for 12.2 k speech service is given.

关键词： code division multiple access Probability Resource allocation Simulation Time division multiple access

A New Performance Analysis Method of Optical code division multiple access Systems with An Optical Hard-Limiter

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The Journal of China Universities of Posts and Telecommunications 2001年第4期8卷 18-21页

作者： LI Xiao bin, ZHAO Xiao hui, GU Hai jun (Department of Telecommunication Engineering, Jilin University, Changchun 130012, P.R. China) Department of Telecommunication Engineering Jilin University Changchun 130012 P.R. China

A new performance analysis method of Optical code division multiple access ( OCDMA ) systems with an optical hard limiter is studied. The bit error probability of the OCDMA system is derived, and the numerical results of the system with and without an ideal optical hard limiter are analyzed respectively. The results show that although the derived expression is different from the one derived by J A Salehi , the numerical results are the same as those analyzed by J A Salehi, and the numerical result can be easily achieved in this expression.

关键词： optical fiber communication code division multiple access optical orthogonal codes optical hard limiter

Direct sequence code division multiple access based on multiwavelet packet transform

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Progress in Natural Science:Materials International 2001年第9期 77-82页

作者：陈俊丽焦李成杨新星 China Key Laboratory for Radar Signal Processing Xidian University Xi’ an 710071

A new code division multiple access of direct sequence based on multiwavelet packet transform is proposed, which can suppress multiple access interference effectively and improve the performance of system remarkably i... 详细信息

关键词： multiwavelet packet transform direct sequence code division multiple access interference muUipath delay.

Successive quadratic programming multiuser detector

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Journal of Systems Engineering and Electronics 2007年第1期18卷 8-13页

作者： Mu Xuewen Zhang Yaling Liu Sanyang Dept. of Applied Mathematics Xidian Univ. Xi'an 710071 E R. China Dept. of Computer Science and Technology Xi'an Univ. of Science and Technology Xi'an 710054 P. R. China

Based on the semidefinite programming relaxation of the CDMA maximum likelihood multiuser detection problem, a detection strategy by the successive quadratic programming algorithm is presented. Coupled with the randomized cut generation scheme, the suboptimal solution of the multiuser detection problem in obtained. Compared to the interior point methods previously reported based on semidefmite programming, simulations demonstrate that the successive quadratic programming algorithm often yields the similar BER performances of the multiuser detection problem. But the average CPU time of this approach is significantly reduced.

关键词： code division multiple access Multiuser detection Semidefinite programming Successive quadratic programming.

Exploration of multiple access Interference Suppression Based on Multi-user Detection

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Chinese Journal of Electronics 2019年第4期28卷 835-840页

作者： WU Tao JING Xiaojun Beijing University of Posts and Telecommunications

A multi-user detection algorithm for multiple access interference suppression combined with the minimum mean squared error and an artificial fish swarm algorithm is proposed. By taking advantage of the artificial fish swarm algorithm, the proposed algorithm can quickly converge to the optimal solution. The variation in the minimum mean squared error based test results is assigned to the artificial fish swarm algorithm, which is regarded as the initial state of artificial fish. The simulation results show that the proposed algorithm has a better multi-user capacity performance and lower bit-error rate than the minimum mean squared error detector.

关键词： multiple access interference suppression Minimum mean squared error Artificial fish swarm algorithm Multi-user detection algorithm code division multiple access

An underwater acoustic direct sequence spread spectrum communication system using dual spread spectrum code

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Frontiers of Information Technology & Electronic Engineering 2018年第8期19卷 972-983页

作者： Lan-jun LIU Jian-fen LI Lin ZHOU Peng ZHAI Hao ZHAO Jiu-cai JIN Zhi-chao LV College of Engineering Ocean University of China The First Institute of Oceanography State Oceanic Administration College of Underwater Acoustic Engineering Harbin Engineering University

With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access(CDMA) based underwater networks, a direct sequence spread spectrum based underwater acoustic communication system using dual spread spectrum code is proposed. To solve the contradictions between the information data rate and the accuracy of Doppler estimation, channel estimation, and frame synchronization, a data frame structure based on dual spread spectrum code is designed. A long spread spectrum code is used as the training sequence, which can be used for data frame detection and synchronization, Doppler estimation, and channel estimation. A short spread spectrum code is used to modulate the effective information data. A delay cross-correlation algorithm is used for Doppler estimation, and a correlation algorithm is used for channel estimation. For underwater networking, each user is assigned a different pair of spread spectrum codes. Simulation results show that the system has a good anti-multipath, anti-interference, and anti-Doppler performance, the bit error rate can be smaller than 10^(-6) when the signal-to-noise ratio is larger than-10 dB, the data rate can be as high as 355 bits/s, and the system can be used in the downlink of CDMA based networks.

关键词： Underwater acoustic communication Direct sequence spread spectrum Doppler estimation and compensation Channel estimation and equalization Gold code Single carrier code division multiple access

Incoherent broadband optical pulse generation using an optical gate

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Chinese Optics Letters 2008年第9期6卷 638-639页

作者：陈彪江琼 Centre for Optical and Electromagnetic Research Zhejiang University

In two-dimensional （2D） time-spreading/wavelength-hopping optical code division multiple access （OCDMA） systems, employing less coherent broadband optical pulse sources allows lower electrical operating rate and better system performance. An optical gate based scheme for generating weakly coherent （approximately incoherent） broadband optical pulses was proposed and experimentally demonstrated. In this scheme, the terahertz optical asymmetric demultiplexer, together with a coherent narrowband control pulse source, turns an incoherent broadband continuous-wave （CW） light source into the required pulse source.

关键词： code division multiple access Electromagnetic waves Gates (transistor) Laser pulses Light Light pulse generators Light sources Lighting Telecommunication systems

Hybrid WDMA/OCDM system with the capability of encoding multiple wavelength channels by employing one encoder and one corresponding optical code

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Chinese Optics Letters 2010年第8期8卷 745-748页

作者：陈荷肖石林朱敏史杰毕美华 State Key Lab of Advanced Optical Communication Systems and Networks Department of Electronic EngineeringShanghai Jiao Tong University School of Information Science and Engineering Xinjiang University

A hybrid wavelength division multiple access （WDMA）/optical code division multiplexing （OCDM） system is proposed, where the optical code is not the same as the address of every optical network unit （ONU）; rather, the code is a virtual fiber of hybrid passive optical network （PON）. To our knowledge, this is the first report analyzing a single encoder/decoder with a single corresponding optical code being exploited to encode/decode multiple wavelength signals simultaneously. This system enables OCDM to become transparent to ONU so that the existing wavelength division multiplexing （WDM） PON can be upgraded. Thus, redesigning the optical line terminal and ONU can be easily accomplished, and greatly decreasing the number of encoder/decoder becomes possible. In experiment, we only employ two encoder/decoder pairs to combine two WDM-PONs in one fiber. Simulation results confirm the feasibility of the proposed system.

关键词： code division multiple access Encoding (symbols) Fiber optic networks multiplexing equipment Optical communication Wavelength division multiplexing

Optimum Transmitter Power Control in WCDMA Cellular Systems

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Journal of Systems Engineering and Electronics 2002年第1期13卷 80-86页

作者： Qiu Ling & Zhu Jinkang PCN&SS Lab., University of Science and Technology of China, Hefei 230027, P.R. China PCN&SS Lab. University of Science and Technology of China Hefei 230027 P.R. China

Power control is an important technique in WCDMA mobile systems for both increasing system capacity and guaranteeing the required QoS (time delay and wireless link transmission quality) of multimedia services. The optimum power control for narrow band CDMA cellular systems is a problem of single threshold optimization. Because these systems have only one type of traffic and have the same QoS requirement. However, WCDMA mobile system should provide multimedia services and different types of traffic have different QoS requirements. Thus, the power control in WCDMA mobile systems isn't a problem of single threshold optimizing, but turns into the optimizing problem of multi-threshold. We analyze the power control problem in WCDMA cellular mobile systems and propose the optimum transmitter power control algorithm. Three criteria to optimize transmitter power levels of multi-thresholds based on grading the priority orders of multimedia services are proposed. Simulation results show that the proposed algorithms are more effective than conventional algorithms and can provide better performance for WCDMA cellular mobile systems.

关键词： Cellular radio systems code division multiple access Mobile telecommunication systems Multimedia systems Optimization Quality of service