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广义时频二维扩频在加性白高斯噪声信道中的性能 总被引:12,自引:2,他引:10
该文提出了一种广义时频二维扩频的概念。在加性白高斯噪声信道中,给出了这种二维扩频通信方式的发射机、接收机工作原理,分析了二维扩频通信方式的误比特率,同时,给出了二维扩频通信方法的误比特率的仿真结果.结果表明,分析结果与仿真结果相近。 相似文献
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本文阐述了扩频通信的基本原理、四种常用工作方式及其工作特点 ,最后简要介绍了扩频通信技术的应用领域之一———CDMA。 相似文献
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Turbo码是一种具有接近Shannon编码理论极限性能的并行级连码。阐述了一种性能极为优越的低速率超正交Turbo码,它以带宽为代价,在高斯及衰落信道中的性能均优于普通的Tur-bo码,因此适用于扩频通信的CDMA系统。最后给出了仿真结果。 相似文献
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介绍了直接扩频通信技术的理论基础,并给出了一种直接扩频通信系统结构框图。选择m序列作为扩频码序列,QDPSK作为调制方式,采用VHDL语言在MAX+plusⅡ软件平台上实现了该系统发射模块信号仿真,仿真波形达到了预期的效果。 相似文献
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Transform domain communication system is an adaptive anti‐interference system that can dynamically generate interference‐orthogonal waveforms. As a spread spectrum system, its low spectrum efficiency limits potential practical applications. In TDCS, cyclic code shift keying is an orthogonal modulation, whose symbols can be regarded as scalars in different dimensions. However, the constellation is restricted by signal time‐bandwidth product. In this study, extending constellation is proven to be a valid approach to improve spectrum efficiency. The combinatory of multidimensional vectors is designed mathematically to increase the variety of the scalars with the minimum orthogonality damage. On the basis of the design, an efficient modulation scheme, namely, multidimensional parallel combinatory transform domain communication system, is proposed, whose fundamental modulation symbols can be represented by the combinatory of a series of cyclic code shift keying symbols with phase shift keying modulation. Compared with the existing methods, multidimensional parallel combinatory transform domain communication system can achieve a considerably higher spectrum efficiency. The bit error rate performance is also improved to various extents. Theoretical spectrum efficiency and bit error rate of the proposed method are derived for additive white Gaussian noise and typical multipath fading channels. System with different spectral conditions and channel estimation methods is also simulated and analyzed to confirm the practical usability. 相似文献
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Different modulation schemes supporting multiple data rates in a Direct Sequence Code Division Multiple Access (DS-CDMA) system are studied. Both AWGN and multipath Rayleigh fading channels are considered. It is shown that the multi processing-gain scheme and the multi-channel scheme have almost the same performance. However, the multi-channel scheme may have some advantages due to easier code design and multiuser receiver construction. The drawback though, is the need for linear amplifiers also in mobile terminals. A multi-modulation scheme is also possible, but the performance for the users with the high data rates are significantly worse than for the other schemes. Furthermore multi chip-rate, parallel combinatory spread spectrum (PC/SS), pulse position modulation (PPM) and variable duty cycle schemes are discussed briefly. 相似文献
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介绍通过计算机增强型并口EPP协议和CPLD实现DSP与计算机并口双向高速数据通信,并详细分析了计算机增强型并口的工作方式,给出了具体的实现方案。该设计实现了计算机和DSP之间的高速数据交换,已经应用到某实时图像处理系统的图像数据传输模块中,并具有一定的通用性,可以应用到其他的科研项目中。 相似文献
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根据数据链路层通信协议的一般格式,对串口监听工具截取的Power-One通信电源监控系统中的通信信息进行了逻辑推理和分析,破解了其通信协议的格式和各种通信命令。实验表明,破解结果正确无误。对于通信电源分布式监控系统通信协议的设计和实现,具有一定的借鉴意义。 相似文献
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Gifford D. Lucassen J. Berlin S. 《Selected Areas in Communications, IEEE Journal on》1985,3(3):457-467
A new type of information system is described that combines personal computers, broadcast data communication, and bidirectional communication. The system is designed to use broadcast communication whenever possible to deliver information to personal computers, which are used for data storage, indexing, and retrieval. This paper starts with an overview of the system, and then discuss the problem of reliable digital broadcast communication in some detail. A parameterized broadcast protocol is described, and we show how to choose protocol parameters based on observed channel error characteristics. A flexible encryption-based protection system is included in the protocol. We discuss the implementation of the system on contemporary personal computers. A broadcast system based on these ideas is now operating in Boston area homes. 相似文献
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多址接入控制协议是网络的重要组成部分,特别是在分布式网络中,它直接影响网络的性能。随着技术的发展,如何将物理层和多址接入层有效的结合起来,如何在接入时可以有效的利用资源,这些因素对网络性能上的提升具有重要意义和价值。本文研究了高通公司提出的Flash Lin Q通信系统,并且详细介绍了Flash Lin Q通信系统所采用的分布式调度协议,该协议是一种高效的并且有效利用空间资源的多址接入协议,相比于RTS/CTS机制的CSMA/CA机制的多址接入协议有较大的增益。协议可以在信号覆盖范围之内实现多条链路的并行传输,增加了网络的吞吐量,改善了网络的性能。 相似文献
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This paper proposes a simple assembly/disassembly part (ADP) for the signalling system no. 7 (SS7) protocol to reduce the signalling traffic loads in intelligent networks (IN) and personal communication service (PCS) networks. The ADP combines two or more messages with the same destinations into a single message, thereby reducing signalling traffic without affecting SS7 protocol operations. The numerical results show that the proposed method can reduce traffic among signalling points 9∼17%. 相似文献