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Joint power control based on service factor for code division multiple access system
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作者 陈波 戎蒙恬 胡威 《Journal of Shanghai University(English Edition)》 CAS 2008年第5期414-418,共5页
An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex (TDD)-code division multiple access (CDMA) systems are analyzed. A ... An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex (TDD)-code division multiple access (CDMA) systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against link gain changes, and outperforms the reference algorithms. 展开更多
关键词 code division multiple access (cdma time division duplex (TDD) power control Markov process service factor
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BER Performance of Space-Time Coded MMSE DFE for Wideband Code Division Multiple Access (WCDMA)
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作者 Sanjay Kumar SHARMA S. Naseem AHMAD 《International Journal of Communications, Network and System Sciences》 2009年第4期276-282,共7页
In recent times, there has been growing interests in integration of voice, data and video traffic in wireless communication networks. With these growing interests, WCDMA has immerged as an attractive access technique.... In recent times, there has been growing interests in integration of voice, data and video traffic in wireless communication networks. With these growing interests, WCDMA has immerged as an attractive access technique. The performance of WCDMA system is deteriorated in presence of multipath fading environment. The paper presents space-time coded minimum mean square error (MMSE) Decision Feedback Equalizer (DFE) for wideband code division multiple access (WCDMA) in a frequency selective channel. The filter coefficients in MMSE DFE are optimized to suppress noise, intersymbol interference (ISI), and multiple access interference (MAI) with reasonable system complexity. For the above structure, we have presented the estimation of BER for a MMSE DFE using computer simulation experiments. The simulation includes the effects of additive white Gaussian noise, multipath fading and multiple access interference (MAI). Furthermore, the performance is compared with standard linear equalizer (LE) and RAKE receiver. Numerical and simulation results show that the MMSE DFE exhibits significant performance improvement over the standard linear equalizer (LE) and RAKE receiver. 展开更多
关键词 Decision Feedback EQUALIZER multiple access Interference (MAI) RAKE Receiver Transmit Diversity Wideband code-division multiple-access (Wcdma) Bit Error Rate (BER)
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A multiple copyright identification watermarking algorithm based on code division multiple access
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作者 张帆 li Jie +1 位作者 Su Yuting Zhang Chuntian 《High Technology Letters》 EI CAS 2008年第4期377-383,共7页
A multiple watermarking algorithm is presented according to the multiple accessing technique of the code division multiple access (CDMA) system. Multiple watermarks are embedded into digital images in the wavelet tr... A multiple watermarking algorithm is presented according to the multiple accessing technique of the code division multiple access (CDMA) system. Multiple watermarks are embedded into digital images in the wavelet transform domain. Each of the watermarks is embedded and extracted independently without impacts to each other. Multiple watermarks are convolution encoded and block interleaved, and the orthogonal Gold sequences are used to spread spectrum of the copyright messages. CDMA encoded water-mark messages are embedded into the wavelet sub-bands excluding the wavelet HH1 sub-bands. The embedment amplitude is decided by Watson' s perceptual model of wavelet transform domain, and the embedmeut position in the selected wavelet sub-bands is decided randomly by a pseudo-random noise (PN) sequence. As a blind watermm'king algorithm, watermarks are extracted without original image. The watermarking capacity of proposed algorithm is also discussed. When two watermarks are embedded in an image at the same time, the capacity is larger than the capacity when a single watermark is embedded, and is smaller than the sum of the capacity of two separately embedded watermarks. Experimental results show that the proposed algorithm improves the detection bits error rate (BER) observably, and the multiple watermarks have a preferable robustness and invisibility. 展开更多
关键词 code division multiple access (cdma WATERMARKING convolutional coding
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Analysis and Simulation for Capacity of Time Division-Synchronous Code Division Multiple Access System 被引量:1
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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) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2002年第4期91-97,共7页
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 interferenc... 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. 展开更多
关键词 code division multiple access PROBABILITY Resource allocation SIMULATION Time division multiple access
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A NEW DECODER OF SYNCHRONOUS OPTICAL CODE DIVISION MULTIPLE ACCESS SYSTEMS USING SEGMENTED CORRELATION
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作者 Li Ou Wu Jiangxing Lan Julong(National Digital Switching System Engineering & Technology Research Center, Zhengzhou 450002) 《Journal of Electronics(China)》 2001年第2期135-139,共5页
A new segmented correlating decoder of synchronous optical CDMA using modified prime sequence codes is proposed. The performance of the proposed system is analyzed under the assumption of Poisson shot noise model for ... A new segmented correlating decoder of synchronous optical CDMA using modified prime sequence codes is proposed. The performance of the proposed system is analyzed under the assumption of Poisson shot noise model for the receiver photodetector. The decoder technique is shown to be more effective to improve the bit error probability performance than the method using an optical hard-limiter. 展开更多
关键词 SYNCHRONOUS optical cdma PRIME codeS multiple access system SEGMENTED CORRELATION
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Performance analysis of quantum access network using code division multiple access model
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作者 胡林曦 杨灿 何广强 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第6期37-41,共5页
A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of ... A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of the code. Recently,the chaotic phase shifters were proposed to guarantee the orthogonality by different chaotic signals and spread the spectral content of the quantum states. In this letter, we propose to implement the code division multiple access quantum network by using chaotic phase shifters and synchronization. Due to the orthogonality of the different chaotic phase shifter, every pair of users can faithfully transmit quantum information through a common channel and have little crosstalk between different users. Meanwhile, the broadband spectra of chaotic signals efficiently help the quantum states to defend against channel loss and noise. 展开更多
关键词 quantum access network chaotic phase shifter code division multiple access
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Reservation-based dynamic admission control scheme for wideband code division multiple access systems
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作者 A.Y.Al-nahari S.A.El-Dolil +1 位作者 M.I.Dessouky F.E.Abd El-Samie 《Journal of Central South University》 SCIE EI CAS 2012年第2期393-401,共9页
Call admission control (CAC) and resource reservation (RR) for mobile communication are two important factors that guarantee system efficiency and quality of service (QoS) required for different services in a very sca... Call admission control (CAC) and resource reservation (RR) for mobile communication are two important factors that guarantee system efficiency and quality of service (QoS) required for different services in a very scarce resource as the radio spectrum. A new scheme was proposed which extends the concepts of resource sharing and reservations for wideband code division multiple access (WCDMA) systems with a unique feature of soft capacity. Voice and data traffic were considered. The traffic is further classified into handoff and new requests. The reservation thresholds were dynamically adjusted according to the traffic pattern and mobility prediction in order to achieve the maximum channel utilization, while guaranteeing different QoS constraints. The performance of proposed scheme was evaluated using Markov models. New call blocking probability, handoff call dropping probability, and channel utilization were used as benchmarks for the proposed scheme. 展开更多
关键词 admission control resource reservation wideband code division multiple access resource utilization
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A passive optical network based on optical code division multiplexing and time division multiple access technology
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作者 张崇富 Qiu Kun 《High Technology Letters》 EI CAS 2007年第3期302-306,共5页
A passive optical network (PON) scheme based on optical code division multiplexing (OCDM) for the downstream traffics is proposed and analyzed in detail. In the PON, the downstream traffics are broadcasted by OCDM... A passive optical network (PON) scheme based on optical code division multiplexing (OCDM) for the downstream traffics is proposed and analyzed in detail. In the PON, the downstream traffics are broadcasted by OCDM technology to guarantee the security, while the upstream traffics pass through the same optical fiber by the common time division multiple access (TDMA) technology to decrease the cost. This schemes are denoted as OCDM/TDMA-PON, which can be applied to an optical access network (OAN) with full services on demand, such as Internet protocol, video on demand, tele-presence and high quality audio. The proposed OCDM/TDMA-PON scheme combines advantages of PON, TDMA, and OCDM technology. Simulation results indicate that the designed scheme improves the OAN performance, and enhances flexibility and scalability of the system. 展开更多
关键词 passive optical network (PON) optical code division multiplexing (OCDM) time division multiple access (TDMA) optical orthogonal code (OOC) optical line terminator (OLT) optical network units (ONU)
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Performance Analysis of Multiple User Optical Code Division Multiple Access
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作者 Himanshu Monga R. S. Kaler 《Optics and Photonics Journal》 2014年第2期21-25,共5页
In this paper, we discuss and analyze an optical code division multiple access for multiple user system. Media access control implementation has been considered. For fulfilling the huge need of bandwidth services, tec... In this paper, we discuss and analyze an optical code division multiple access for multiple user system. Media access control implementation has been considered. For fulfilling the huge need of bandwidth services, technology tends to move to optical networks and three major optical systems come into existence. Code division of the optical network is most used and real concept interacted with users up to this time. Optical code division multiple access provides complete spectrum to each and every user for the time of accessing the channel. In the paper, we have proposed network architecture with optical encoder and decoder along with optical code translator which is supporting multiple user systems. We integrate the code translator with encoding and decoding of optical code to use the optical network at full extent and present the simulation validation results of 6 Gb/s 3-hop transmission by use of proposed architecture. Further, we have implemented experimentation with 6 users 3 Gb/s optical code division multiple access network. Through simulation structure, it is shown that the combination of encoding with EDFA in multiple user environment system provides improvement in bit error rate and also improves the multiple access interference. With increase of users in the network, MAI value increases and our proposed scheme controls interference in the network. 展开更多
关键词 OPTICAL code division multiple access Strong INTERFERENCE Weak INTERFERENCE Bit Error Rate OPTICAL Encoding Laser DIODE Source multiple access INTERFERENCE
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A Low Complexity VCS Method for PAPR Reduction in Multicarrier Code Division Multiple Access
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作者 Si-Si Liu Yue Xiao Qing-Song Wen Shao-Qian Li 《Journal of Electronic Science and Technology of China》 2007年第2期102-106,共5页
This paper investigates a peak to average power ratio (PAPR) reduction method in multicarrier code division multiple access (MC-CDMA) system. Variable code sets (VCS), a spreading codes selection scheme, can imp... This paper investigates a peak to average power ratio (PAPR) reduction method in multicarrier code division multiple access (MC-CDMA) system. Variable code sets (VCS), a spreading codes selection scheme, can improve the PAPR property of the MC-CDMA signals, but this technique requires an exhaustive search over the combinations of spreading code sets. It is observed that when the number of active users increases, the search complexity will increase exponentially. Based on this fact, we propose a low complexity VCS (LC-VCS) method to reduce the computational complexity. The basic idea of LC-VCS is to derive new signals using the relationship between candidature signals. Simulation results show that the proposed approach can reduce PAPR with lower comtational pucomplexity. In addition, it can be blindly received without any side information. 展开更多
关键词 Low complexity variable code sets multicarrier code division multiple access (MC-cdma) peak to average power ratio variable code sets.
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Hybrid Deep Learning-Based Adaptive Multiple Access Schemes Underwater Wireless Networks
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作者 D.Anitha R.A.Karthika 《Intelligent Automation & Soft Computing》 SCIE 2023年第2期2463-2477,共15页
Achieving sound communication systems in Under Water Acoustic(UWA)environment remains challenging for researchers.The communication scheme is complex since these acoustic channels exhibit uneven characteristics such a... Achieving sound communication systems in Under Water Acoustic(UWA)environment remains challenging for researchers.The communication scheme is complex since these acoustic channels exhibit uneven characteristics such as long propagation delay and irregular Doppler shifts.The development of machine and deep learning algorithms has reduced the burden of achieving reli-able and good communication schemes in the underwater acoustic environment.This paper proposes a novel intelligent selection method between the different modulation schemes such as Code Division Multiple Access(CDMA),Time Divi-sion Multiple Access(TDMA),and Orthogonal Frequency Division Multiplexing(OFDM)techniques using the hybrid combination of the convolutional neural net-works(CNN)and ensemble single feedforward layers(SFL).The convolutional neural networks are used for channel feature extraction,and boosted ensembled feedforward layers are used for modulation selection based on the CNN outputs.The extensive experimentation is carried out and compared with other hybrid learning models and conventional methods.Simulation results demonstrate that the performance of the proposed hybrid learning model has achieved nearly 98%accuracy and a 30%increase in BER performance which outperformed the other learning models in achieving the communication schemes under dynamic underwater environments. 展开更多
关键词 code division multiple access time division multiple access convolutional neural networks feedforward layers
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Frameworks of Non-Orthogonal Multiple Access Techniques in Cognitive Radio Communication Systems 被引量:3
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作者 Prabhat Thakur Alok Kumar +2 位作者 S Pandit G Singh S N Satashia 《China Communications》 SCIE CSCD 2019年第6期129-149,共21页
Recently,the increasing demand of radio spectrum for the next generation communication systems due to the explosive growth of applications appetite for bandwidths has led to the problem of spectrum scarcity.The potent... Recently,the increasing demand of radio spectrum for the next generation communication systems due to the explosive growth of applications appetite for bandwidths has led to the problem of spectrum scarcity.The potential approaches among the proposed solutions to resolve this issue are well explored cognitive radio(CR)technology and recently introduced non-orthogonal multiple access(NOMA)techniques.Both the techniques are employed for efficient spectrum utilization and assure the significant improvement in the spectral efficiency.Further,the significant improvement in spectral efficiency can be achieved by combining both the techniques.Since the CR is well-explored technique as compared to that of the NOMA in the field of communication,therefore it is worth and wise to implement this technique over the CR.In this article,we have presented the frameworks of NOMA implementation over CR as well as the feasibility of proposed frameworks.Further,the differences between proposed CR-NOMA and conventional CR frameworks are discussed.Finally,the potential issues regarding the implementation of CR-NOMA are explored. 展开更多
关键词 cognitive radio channel state information non-orthogonal multiple access power division multiple access superposition-coding successive-interference-cancellation
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SAC-OCDMA系统三分支信号检测方案
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作者 陈富军 《光通信技术》 北大核心 2024年第1期66-70,共5页
为了解决三分支信号检测(TBSD)方案的上界表达式不精确的问题,提出了一种频谱-振幅编码光码分多址(SAC-OCDMA)系统TBSD方案,建立了一个严谨的数学模型,并对该方案进行了数值评估和仿真。仿真结果表明,该方案在传输速率为500 Mb/s、1 Gb/... 为了解决三分支信号检测(TBSD)方案的上界表达式不精确的问题,提出了一种频谱-振幅编码光码分多址(SAC-OCDMA)系统TBSD方案,建立了一个严谨的数学模型,并对该方案进行了数值评估和仿真。仿真结果表明,该方案在传输速率为500 Mb/s、1 Gb/s时能够完全消除多用户干扰(MUI),而在传输速率为5 Gb/s时则可以消除大部分MUI,证明了数学模型的精确性。 展开更多
关键词 光码分多址系统 多用户干扰 信号检测 三分支信号检测
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IMPROVING THE CAPACITY OF MULTI-CODE MULTIMEDIA CDMA SYSTEM 被引量:1
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作者 Pan Su Liu Shengmei 《Journal of Electronics(China)》 2007年第4期557-559,共3页
A novel method for improving the capacity of multi-code multimedia Code Division Mul- tiple Access (CDMA) systems is proposed. By factitiously improving the transmission bit rate of the call, the number of the orthogo... A novel method for improving the capacity of multi-code multimedia Code Division Mul- tiple Access (CDMA) systems is proposed. By factitiously improving the transmission bit rate of the call, the number of the orthogonal codes used by a user is increased which leads to the decreasing of the interference. Simulation results shows that the proposed scheme results in better throughput than traditional multi-code CDMA systems. 展开更多
关键词 Capacity MULTIMEDIA code division multiple access (cdma
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A Novel Optical Code Division Multiple Access Ring Network System for LAN 被引量:1
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作者 WANGYu-Bao GAOYi-Ran MAWen-hua WUJian LINJin-Tong 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2004年第3期5-9,共5页
In this paper the impact factors on the optical fiber LAN network with ring topology are considered. The couple ratio, the self-ring effect, the Multiple-Access Interference (MAI), and the channel noises are the main ... In this paper the impact factors on the optical fiber LAN network with ring topology are considered. The couple ratio, the self-ring effect, the Multiple-Access Interference (MAI), and the channel noises are the main factors degrading the system performance. We develop a systematic method that employs the smallest p multiplication method to analyze the optimization of the ring network. The results show that choosing an optimal couple ratio and power control will enhance the system performance dramatically. In addition, the “self-ring” interference and MAI can be suppressed by power control to some extent. 展开更多
关键词 ring network OPTIMIZATION power control optical code division multiple access
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A Random Multi-Access Method for Data Services in CDMA Cellular System
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作者 李振 尤肖虎 《Journal of Southeast University(English Edition)》 EI CAS 1997年第2期8-12,共5页
ARandomMultiAccessMethodforDataServicesinCDMACelularSystemLiZhen(李振)YouXiaohu(尤肖虎)(NationalMobileCommunicat... ARandomMultiAccessMethodforDataServicesinCDMACelularSystemLiZhen(李振)YouXiaohu(尤肖虎)(NationalMobileCommunicationsResearchLabor... 展开更多
关键词 multiple access code division multi access mobile communication
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A New Performance Analysis Method of Optical Code Division Multiple Access Systems with An Optical Hard-Limiter
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作者 LI Xiao bin, ZHAO Xiao hui, GU Hai jun (Department of Telecommunication Engineering, Jilin University, Changchun 130012, P.R. China) 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2001年第4期18-21,共4页
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 ... 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. 展开更多
关键词 optical fiber communication code division multiple access optical orthogonal codes optical hard limiter
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Modeling and Simulation of CDMA Codes in Scilab
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作者 Mouhamed Fadel Diagana Serigne Bira Gueye 《International Journal of Communications, Network and System Sciences》 2015年第7期274-281,共8页
Prior to hardware implementation, simulation is an important step in the study of systems such as Direct Sequence Code Division Multiple Access (DS-CDMA). A useful technique is presented, allowing to model and simulat... Prior to hardware implementation, simulation is an important step in the study of systems such as Direct Sequence Code Division Multiple Access (DS-CDMA). A useful technique is presented, allowing to model and simulate Linear Feedback Shift Register (LFSR) for CDMA. It uses the Scilab package and its modeling tool for dynamical systems Xcos. PN-Generators are designed for the quadrature-phase modulation and the Gold Code Generator for Global Positioning System (GPS). This study gives a great flexibility in the conception of LFSR and the analysis of Maximum Length Sequences (MLS) used by spread spectrum systems. Interesting results have been obtained, which allow the verification of generated sequences and their exploitation by signal processing tools. 展开更多
关键词 code division multiple access (cdma) Linear Feedback Shift Register (LFSR) Maximum Length SEQUENCE (MLS) SPREAD-SPECTRUM SCILAB Xcos Direct SEQUENCE Spread Spectrum (DSSS)
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CONVOLUTIONAL CODED DS/CDMA WITH TWO SETS OF ORTHOGONAL SPREADING SEQUENCES AND ITERATIVE DETECTION
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作者 Wei Yimin Yi Xiaoxin Shen Yuehong(Nanjing Institute of Communication Engineering, Nanjing 210016) 《Journal of Electronics(China)》 2002年第3期276-279,共4页
In this letter a convolutional coded Direct-Sequence Code-Division Multiple Ac-cess(DS/CDMA) concept is introduced. The number of the users it can accommodate is greater than the spreading factor N. Each of the availa... In this letter a convolutional coded Direct-Sequence Code-Division Multiple Ac-cess(DS/CDMA) concept is introduced. The number of the users it can accommodate is greater than the spreading factor N. Each of the available orthogonal spreading sequences of length N is assigned to one of the first N users which employ a common Pseudo-Noise (PN) scrambling sequence. When the number of users K exceeds N, say K= N + M with M < N, the M additional users reuse M of those orthogonal spreading sequences but in combination with another PN scrambling sequence. An iterative multistage detection technique aided by Viterbi decoding is used to cancel the interference between the two sets of users when K > N. The proposed technique thus accommodates N users without any mutual interference and a number of additional users almost without signal-to-noise ratio penalty. 展开更多
关键词 coded cdma Cell capacity multiple access
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CLOSED-FORM SPACE-TIME CHANNEL BLIND ESTIMATION FOR SPACE-TIME CODED MC-CDMA SYTEMS WITH UNIFORM LINEAR ARRAY
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作者 Zeng Yanxing Yin Qinye Luo Ming Zhang Jianguo 《Journal of Electronics(China)》 2006年第3期321-327,共7页
This paper proposes a closed-form joint space-time channel and Direction Of Arrival (DOA) blind estimation algorithm for space-thne coded Multi-Carrier Code Division Multiple Access (MC-CDMA) systems equipped with... This paper proposes a closed-form joint space-time channel and Direction Of Arrival (DOA) blind estimation algorithm for space-thne coded Multi-Carrier Code Division Multiple Access (MC-CDMA) systems equipped with a Uniform Linear Array (ULA) at the base station in frequency-selective fading environments. The algorithm uses an ESPRIT-like method to separate multiple co-channel users with different impinging DOAs. As a result, the DOAs for multiple users are obtained. In particular, a set of signal subspaces, every one of which is spanned by the space-time vector channels of an individual user, are also obtained. From these signal subspaces, the space-time channels of multiple users are estimated using the subspace method. Computer simulations illustrate both the validity and the overall performance of the proposed scheme. 展开更多
关键词 Multi-Carrier code division multiple Space-time channel Antenna array Direction Of Arrival access (MC-cdma) Space-Time Coding (STC) (DOA)
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