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针对正交频分复用(OFDM)系统的高峰均功率比问题,介绍了一种改进的载波保留(TR)方法,该算法应用时域核函数构造时域核函数矩阵并进行缩放参数优化,迭代过程复杂度低且性能良好.设计了一种简化的OFDM发射机方案以验证该算法在实际系统中的有效性,给出了在FPGA上实现该方案的整体架构及关键模块.硬件测试结果表明该OFDM发射机的峰均比得到了有效抑制,验证了该TR算法的正确性,证明其有较好的应用前景. 相似文献
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基于FPGA的实时光OFDM发射机的研究 总被引:4,自引:4,他引:0
基于Xilinx现场可编程门阵列(FPGA)实时产生正交频分复用(OFDM)信号,其中包括伪随机二进制序列发生器(PRBS)实现、完全并行运算反傅里叶变换(IFFT)技术的应用以及数模转换(DAC)接口电路的设计等,OFDM电信号解调后的星座图具有较好的收敛性,相应的误差矢量幅度(EVM)为4.42%。当发射机与接收端存在采样频率偏差时,各子载数据产生不同的相位旋转,系统误比特率(BER)显著升高,采样频率同步后系统性能得到明显改善。通过搭建强度调制直接检测光OFDM(O-OFDM)实验系统,传输200km标准单模光纤(SSMF)后,在接收端对O-OFDM信号进行了离线处理,与背靠背(BTB)传输相比,光功率代价小于0.6dB,实验结果表明,所设计的O-OFDM发射机具有较好的性能。 相似文献
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主要讨论了OFDM(正交频分复用)系统中使用数字中频的优点、在发射机和接收机中的实现方案.重点叙述了数字中频中两个关键模块NcO(数控振荡器)和成型滤波器在FPGA(现场可编程门阵列)中的设计.在NCO的设计过程中采用有效、简便的方法一查表法;成型滤波器使用了固定系数的有限冲击响应滤波器.介绍了使用分布式运算法和CSD(典范带符号)方法设计成型滤波器的原理,分析了数字量化误差. 相似文献
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设计了一种基于IFFT/FFT的高效OFDM调制解调器,实现数模同播音频广播系统中数字音频信号的OFDM调制解调,包括发射机中用于形成OFDM符号的时域与频域交织模块、OFDM调制模块和接收机中OFDM解调模块、时域与频域解交织模块。通过对IFFT/FFT算法的改进,该OFDM调制解调器中数据的输入顺序和输出顺序相同,不需要进行顺序输人逆序输出,并且可以把现有基2的幂次方的FFT变换扩展到任意点,实现适用于任意点的IFT/FFT,简化了IFFT/FFT模块本身和交织/解交织的资源消耗,巧妙地节省了系统所需的资源。 相似文献
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本文介绍了一个DAB(Digital Audio Broadcasting)原型发射机数字基带部分的设计与实现,包括复接器、信道编码器和OFDM调制器.它的内部功能和外部特性完全符合ETS 300 401和其他相关标准,支持多种业务类型,具有方便的用户接口.它的I/O接口和核心部件采用基于通用内部接口的模块化设计,可根据用户需要灵活配置.同现有的发射机产品相比,具有成本低,易于调试,可灵活配置等特点. 相似文献
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OFDM系统设计及其Matlab实现 总被引:4,自引:4,他引:0
文章对OFDM系统调制与解调技术进行了解析,得到了OFDM符号的一般表达式,给出了OFDM系统参数设计公式和加窗技术的原理及基于IFFT/FFT实现的OFDM系统模型,阐述了运用IDFT和DFT实现OFDM系统的根源所在;对Turbo码-OFDM系统进行了Matlab仿真,并根据特性曲线得出了相关结论. 相似文献
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基于OFDM技术的中压电力线通信中降峰平比设计 总被引:1,自引:0,他引:1
正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统的一个主要缺点是峰值功率与平均功率比过高,即峰值平均功率比(Peak to Average Power Ratio,PAPR)问题。这要求系统内的一些部件需要较大的线性动态范围,以避免信号失真引起传输信号的频谱扩散及带内失真引起的误码率增加,从而增加系统实现的难度和成本。本文从工程实现复杂度与资源使用情况的综合考虑,提出了一种基于OFDM技术的中压电力线通信芯片中降低峰平比的设计。该设计方法资源耗费小,能有效地降低峰平比,而且易于实现。 相似文献
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OFDM技术在GSM语音信道中的应用 总被引:1,自引:0,他引:1
远距离数据传输以及数据传输的保密性向来是人们比较关注的问题,使用语音信道传输数据信息是一种可选的方案。利用GSM信道,结合OFDM技术,将电脑、手机、A/D、D/A组成一个系统,可以实现一种远距离数据传输平台。针对OFDM技术特点,实现了GSM语音信道OFDM调制解调系统,经过多次实验测试,平均误码率曲线表明设计达到了最初的设计要求,在话音保密数据通信及其他数据传输上有较好的应用前景。 相似文献
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基于无线局域网(Wireless Local Area Networks,WLAN)的正交频分复用(Orthogonal Frequency DivisionMultiplexing,OFDM)信号,提出了一种低成本、小体积的接收机设计方案。采用零中频下变频技术,简化了接收机电路结构,并且通过对影响接收性能关键技术指标的分析,证明该设计能够满足OFDM信号接收解调要求。介绍了一种宽带全直流耦合驱动电路的设计方法,为下变频电路和采样电路间的提供可靠连接,解决含直流宽带信号传输中普遍存在的直流漂移和增益稳定问题。通过实际测试结果验证了接收方案的正确性和工程实用性。 相似文献
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An efficient space-frequency coded OFDM system for broadband wireless communications 总被引:1,自引:0,他引:1
We propose an efficient space-frequency coded orthogonal frequency-division multiplexing (OFDM) system for high-speed transmission over wireless links. The analytical expression for the pairwise probability of the proposed space-frequency coded OFDM system is derived in slow, space- and frequency-selective fading channels. The design criteria of trellis codes used in the proposed system are then developed and discussed. It is shown that the proposed space-frequency coded OFDM can efficiently achieve the full diversity provided by the fading channel with low trellis complexity, while for traditional space-frequency coded OFDM systems, we need to design space-time trellis codes with high trellis complexity to exploit the maximum achievable diversity order. The capacity properties of space-frequency coded OFDM over multipath fading channels are also studied. Numerical results are provided to demonstrate the significant performance improvement obtained by the proposed space-frequency coded OFDM scheme, as well as the excellent outage capacity properties. 相似文献
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研究基于IEEE 802.16d OFDM系统的FPGA实现。首先探讨了基于802.16d的OFDM系统FPGA设计的构架。然后采用VHDL硬件描述语言实现了发送端和接收端各个模块。最后选用了Altera公司CycloneⅡ系列的EP2C35F484C6芯片,在QuartusⅡ软件环境下对VHDL代码进行了综合。 相似文献
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Reza Mohseni Abbas Sheikhi Mohammad Ali Masnadi-Shirazi 《AEUE-International Journal of Electronics and Communications》2010,64(11):999-1008
Orthogonal frequency division multiplexing (OFDM) radar signals have been introduced for high range resolution radars. These signals have prominent properties such as favorable ambiguity function, high bandwidth efficiency, and possibility of use in dual mode radar/communication systems. But the large amplitude fluctuations of the OFDM signal make it susceptible to system nonlinearities. To alleviate this problem, constant envelope OFDM (CE-OFDM) signal has been introduced which combines orthogonal frequency division multiplexing and phase modulation or frequency modulation. Although several works have been reported on OFDM radar signal design, there is no a systematic approach for designing CE-OFDM signals for radar applications. In this paper we will focus on CE-OFDM signal design for radar applications. Two different methods for designing a CE-OFDM signal with favorable ambiguity functions are introduced. The first one is based on modulating a complementary set of sequences on different sub-carriers while the second is based on using a proper single carrier coded signal and then extracting its most similar multicarrier OFDM or CE-OFDM coded signal. 相似文献
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FPGA Synthesis of VHDL OFDM System 总被引:1,自引:0,他引:1
M. A. Mohamed 《Wireless Personal Communications》2013,70(4):1885-1909
This paper presents a novel Field Programmable Gate Array (FPGA) technique to gain approach in the problem of OFDM system implementation. The actual and next communication schemes tend to use OFDM systems in order to provide high baud rates, less intercarrier interference (IC), and less intersymbol interference (ISI). Some examples are IEEE-802.11, IEEE-802.15, IEEE-802.16, 3GPP, MC-CDMA, digital video broadcasting (DVB), wireless USB, and/or wireless firewire among others. Trying to provide a solution to the new devices emerging, slow standard adoption, poor spectrum use, etc. This work presents an FPGA design; validation, and implementation of an OFDM modulator for IEEE-802.16e using a high level design tool, also reports the resources requirements for the presented system. The proposed design is synthesized using high level design tools. The design flow is optimized for fast prototyping which is implemented on the latest generation of FPGA chips. Such an FPGA implementation has the added advantage to modify for changes and improved system performance, e.g. reducing propagation delay. 相似文献