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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 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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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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Uplink Grant-Free Pattern Division Multiple Access (GF-PDMA) for 5G Radio Access 被引量:12
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作者 Wanwei Tang Shaoli Kang +1 位作者 Bin Ren Xinwei Yue 《China Communications》 SCIE CSCD 2018年第4期153-163,共11页
Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-or... Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-orthogonal multiple access(NMA) can support more users for m MTC than orthogonal frequency division multiple access(OFDMA). Applying GF transmission in NMA system becomes an active topic recently. The in-depth study on applying GF transmission in pattern division multiple access(PDMA), a competitive candidate scheme of NMA, is investigated in this paper. The definition, latency and allocation of resource and transmission mechanism for GF-PDMA are discussed in detail. The link-level and system-level evaluations are provided to verify the analysis. The analysis and simulation results demonstrate that the proposed GF-PDMA has lower latency than grant based PDMA(GB-PDMA), possesses strong scalability to confront collision and provides almost 2.15 times gain over GF-OFDMA in terms of supporting the number of active users in the system. 展开更多
关键词 pattern division multiple access(PDMA) grant-free UPLINK massive machinetype communication (mMTC) 5G
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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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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 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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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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Space-division multiple access for CDMA multiuser underwater acoustic communications
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作者 Jingwei Yin Pengyu Du +1 位作者 Guang Yang Huanling Zhou 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第6期1184-1190,共7页
Time reversal mirror (TRM) can use the physical characteristics of the underwater acoustic (UWA) channel to focus on the desired user in multi-user UWA communication. The active average sound intensity (AASI) de... Time reversal mirror (TRM) can use the physical characteristics of the underwater acoustic (UWA) channel to focus on the desired user in multi-user UWA communication. The active average sound intensity (AASI) detector can estimate all azimuths of users with the same frequency band at the same time in order to achieve directional communication by vector combination. Space-division multiple access (SDMA) based on TRM combined with the AASI detector is proposed in this paper, which can make the capacity of the code division multiple access (CDMA) UWA system significantly increase. The simulation and lake test results show that the 7-user UWA multi-user system can achieve low bit error communication. 展开更多
关键词 underwater acoustic (UWA) communication space-division multiple access (SDMA) time reversal mirror (TRM) active average sound intensity (AASI) detector.
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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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Model division multiple access for semantic communications 被引量:7
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作者 Ping ZHANG Xiaodong XU +10 位作者 Chen DONG Kai NIU Haotai LIANG Zijian LIANG Xiaoqi QIN Mengying SUN Hao CHEN Nan MA Wenjun XU Guangyu WANG Xiaofeng TAO 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2023年第6期801-812,共12页
In a multi-user system,system resources should be allocated to different users.In traditional communication systems,system resources generally include time,frequency,space,and power,so multiple access technologies suc... In a multi-user system,system resources should be allocated to different users.In traditional communication systems,system resources generally include time,frequency,space,and power,so multiple access technologies such as time division multiple access(TDMA),frequency division multiple access(FDMA),space division multiple access(SDMA),code division multiple access(CDMA),and non-orthogonal multiple access(NOMA)are widely used.In semantic communication,which is considered a new paradigm of the next-generation communication system,we extract high-dimensional features from signal sources in a model-based artificial intelligence approach from a semantic perspective and construct a model information space for signal sources and channel features.From the high-dimensional semantic space,we excavate the shared and personalized information of semantic information and propose a novel multiple access technology,named model division multiple access(MDMA),which is based on the resource of the semantic domain.From the perspective of information theory,we prove that MDMA can attain more performance gains than traditional multiple access technologies.Simulation results show that MDMA saves more bandwidth resources than traditional multiple access technologies,and that MDMA has at least a 5-dB advantage over NOMA in the additive white Gaussian noise(AWGN)channel under the low signal-to-noise(SNR)condition. 展开更多
关键词 Model division multiple access(MDMA) Semantic communication multiple access
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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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Joint Non-Orthogonal Multiple Access (NOMA) & Walsh-Hadamard Transform: Enhancing the Receiver Performance 被引量:2
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作者 Muhammad Rehan Usman Arsla Khan +1 位作者 Muhammad Arslan Usman Soo young Shin 《China Communications》 SCIE CSCD 2018年第9期160-177,共18页
Non-orthogonal multiple access(NOMA) is a new access method to achieve high performance gains in terms of capacity and throughput, so it is currently under consideration as one of the candidates for fifth generation(5... Non-orthogonal multiple access(NOMA) is a new access method to achieve high performance gains in terms of capacity and throughput, so it is currently under consideration as one of the candidates for fifth generation(5 G) technologies. NOMA utilizes power domain in order to superimpose signals of multiple users in a single transmitted signal. This creates a lot of interference at the receive side. Although the use of successive interference cancellation(SIC) technique reduces the interference, but to further improve the receiver performance, in this paper, we have proposed a joint Walsh-Hadamard transform(WHT) and NOMA approach for achieving better performance gains than the conventional NOMA. WHT is a well-known code used in communication systems and is used as an orthogonal variable spreading factor(OVSF) in communication systems. Application of WHT to NOMA results in low bit error rate(BER) and high throughput performance for both low and high channel gain users. Further, it also reduces peak to average power ratio(PAPR) of the user signal. The results are discussed in terms of comparison between the conventionalNOMA and the proposed technique, which shows that it offers high performance gains in terms of low BER at different SNR levels, reduced PAPR, high user throughput performance and better spectral efficiency. 展开更多
关键词 Bit error rate (BER) non-orthogonal multiple access (NOMA) orthogonal frequency division multiplexing (OFDM) peak to average power ratio (PAPR) successive interference cancellation (SIC) throughput and Walsh-Hadamard transform (WHT).
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A time domain multiple-CFOs and CIRs estimation algorithm over wireless multimedia sensor networks
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作者 姜建 《High Technology Letters》 EI CAS 2009年第3期294-300,共7页
Channel parameters estimation in an orthogonal for the receiver station is a multi-dimensional (MD) frequency division multiple access (OFDMA) system optimization problem, because every user node has a separate lo... Channel parameters estimation in an orthogonal for the receiver station is a multi-dimensional (MD) frequency division multiple access (OFDMA) system optimization problem, because every user node has a separate local oscillator and every transmitter to receiver link has individual carrier frequency offset (CFO) and channel impulse response (CIR) parameters. In order to reduce the computational complexity for MD optimization, a time domain CFOs and CIRs estimation algorithm over the OFDMA based wireless multimedia sensor networks (WMSN) is proposed in this paper. In this algorithm, the receiver station can decouple the signal from every node by correlation based on specially designed training sequences, so that the MD optimization problem is simplified to an 1-D optimal problem. It is proved that the multiple CFOs can be identified from the correlation result using the phase shift of the consecutive training se- quences. Based on the CFOs estimation result, the CIRs can then he estimated according to the minimum mean square error (MMSE) criterion. The theoretic analysis and simulation results show that the proposed algorithm can effectively decouple the signal from different user nodes and the bit error rate (BER) per- formance curves are close to the ideal estimation when the user number is not large. 展开更多
关键词 wireless multimedia sensor networks (WMSN) orthogonal frequency division multiple access (OFDMA) multiple carrier frequency offsets (CFOs) multiple channel impulse responses (CIRs) minimum mean square error (MMSE)
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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 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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不相关多子集零相关区序列集的构造
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作者 崔莉 许成谦 《系统工程与电子技术》 EI CSCD 北大核心 2024年第10期3577-3585,共9页
在多小区环境下的准同步码分多址(quasi-synchronous code-division multiple-access,QS-CDMA)系统中,不相关多子集零相关区(zero correlation zone,ZCZ)序列集不仅可以消除一定时延内来自相同小区的信号干扰,而且可以完全消除来自相邻... 在多小区环境下的准同步码分多址(quasi-synchronous code-division multiple-access,QS-CDMA)系统中,不相关多子集零相关区(zero correlation zone,ZCZ)序列集不仅可以消除一定时延内来自相同小区的信号干扰,而且可以完全消除来自相邻小区的信号干扰。针对如何基于仿酉矩阵构造多子集ZCZ序列集的问题,设计了两种构造方法。具体地,通过构造具有一定特性的多个初始矩阵,再结合仿酉矩阵,进而利用不同的初始矩阵产生不同的ZCZ序列集,且序列集间互不相关。所提方法的核心是多个初始矩阵的设计,方法1通过对离散傅里叶变换(discrete Fourier transform,DFT)矩阵进行分块与叠加实现,方法2利用已有的不相关多子集ZCZ序列集实现。由两种方法得到的构造结果,其参数趋近于最优,为解决多小区环境下的干扰抑制问题提供了新的序列设计方法。 展开更多
关键词 准同步码分多址系统 零相关区 多子集零相关区序列集 仿酉矩阵
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面向用户需求的低轨卫星资源分配算法
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作者 陈发堂 黄淼 金宇峰 《计算机应用》 CSCD 北大核心 2024年第4期1242-1247,共6页
低轨(LEO)卫星多波束通信场景下,传统固定资源分配算法无法满足不同用户对信道容量的差异需求。以适应用户需求分配为主要目标,建立联合信道分配、带宽分配和功率分配的最小供需差优化模型,并引入图样分割多址接入技术(PDMA)提升信道资... 低轨(LEO)卫星多波束通信场景下,传统固定资源分配算法无法满足不同用户对信道容量的差异需求。以适应用户需求分配为主要目标,建立联合信道分配、带宽分配和功率分配的最小供需差优化模型,并引入图样分割多址接入技术(PDMA)提升信道资源的利用率。针对该模型的非凸特性,通过Q-learning算法学习资源分配最优策略为每个用户分配适合的信道容量,并引入奖励阈值进一步改进算法,加快算法的收敛,且使算法达到收敛时供需差异更小。仿真结果表明,改进后的算法收敛速度约是改进前的3.33倍:改进算法能满足更大的用户需求,比改进前Qlearning算法提升14%,是传统固定算法的2.14倍。 展开更多
关键词 低轨卫星 多波束 资源分配 强化学习 图样分割多址接入
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