共查询到20条相似文献,搜索用时 31 毫秒
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This paperpresents the performance evaluation of a portable digital radiophoneinfluencedby the operator's body in urban mobile environments, based on the EVM (errorvector magnitude) and BER (bit error rate) simulation. The type of digitalmodulation follows to the NADC-TDMA standard. A new probability densityfunction(pdf) is proposed to describe the statistic of the EVM in an AWGNchannelunder frequency non-selective slowly fading situation. The simulation combinesthe modified Doppler power spectrum (MDPS) method and a gray coding(/4-DQPSK modulation with square-root raised cosine (SRRC) shaping filter.The performance evaluation based on BER uses an ideal matched-filter-basedreceiver. The results show that the closer of the distance between theradiophone antenna and the operator's head, the poorer of the EVM and BERperformance. 相似文献
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可见光通信光正交频分复用系统符号分解技术抑制LED非线性失真研究 总被引:1,自引:0,他引:1
传统重复信号限幅(ISC)技术可以减小非线性LED光正交频分复用(O-OFDM)系统的非线性限幅噪声影响。但ISC系统需要多个LED同时发光,同步和硬件实现复杂,并且误码率(BER)随着信道增益差异的增大而变大。基于此,提出基于单个LED的O-OFDM符号分解串行传输系统,对O-OFDM符号进行限幅分解,然后串行组帧,最后输入到单个LED中。推导了系统理论信噪比表达式,并建立了蒙特卡罗误码率和误差矢量幅度(EVM)仿真模型。结果表明,随着符号分解次数增大,EVM和BER性能显著变好,但通信速率略有下降,并且直流偏置会影响EVM和BER性能。本系统实现简单,避免了信道增益差异引起的BER变差问题。 相似文献
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This paper presents a new implementation of a millimeter-wave heterodyne receiver based on six-port technology.The six-port model is implemented in Advanced Design System(ADS) using S-parameter measurements for realistic advanced simulation of a short-range 60 GHz wireless link.Millimeter-wave frequency conversion is performed using a six-port down-converter.The second frequency conversion is performed using conventional means because of low IF.A comparison between the proposed receiver and a conventional balanced millimeter-wave mixer shows that the proposed receiver improves conversion loss and I/Q phase stability over the local oscillator(LO) and RF power ranges.The results of demodulating a V-band quadrature phase-shift keying(QPSK) signal at a high data rate of 100 Mb/s-1 Gb/s are discussed.The results of a bit error rate(BER) and error vector magnitude(EVM) analysis prove that the proposed architecture can be successfully used for wireless link transmission up to 10 m. 相似文献
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Hai-Han Hsiao-Wen Cheng-Yuan Hai-Wei Hsuan-Wen Sheng-Sung Shah-Jye 《Optical Fiber Technology》2008,14(4):317-322
A full-duplex radio-over-fiber (ROF) transport system based on two modes injection-locked Fabry–Perot laser diode (FP LD) is proposed and demonstrated. Performances over a 40-km standard single-mode fiber (SMF) full-duplex transmission were investigated. Good performances of bit error rate (BER) and error vector magnitude (EVM) were obtained in our proposed systems. Since our proposed systems use only one FP LD as light source for both down-link and up-link transmissions, it reveals a prominent alternative with advantages in simplicity and cost. 相似文献
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EVM simulation and analysis in digital transmitter 总被引:1,自引:0,他引:1
The error vector magnitude (EVM) is extensively applied as a metric for digital transmitter signal quality compliance in modern communication systems. This article is focused on the effects of local oscillator (LO) phase noise and nonlinear distortion of power amplifier on EVM. This article contributes to below aspects. First, the relationships between EVM and two effects, LO phase noise and nonlinear distortion of power amplifier, are derived and expressed. Second, to simplify the expression, the third-order intermodulation distortion (IMD3) is used to calculate the EVM. Then, an expression for the EVM is derived based on the digital transmitter model that considers local oscillator phase noise and nonlinear distortion of power amplifier. Finally, the math formula of bit error rate (BER) versus EVM is given which can be easier and more useful to predict BER, according to analysis of the relationship between EVM and signal to noise rate (SNR), inspired by the works of Rishad, Md. Shahriar and AHM, 2006. Simulations are carried out to display the performance of EVM based on these relationships. 相似文献
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《Microwave Theory and Techniques》2009,57(3):582-588
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基于副载波复用的多输入单输出正交频分复用LED可见光通信系统 总被引:1,自引:0,他引:1
提出了一种基于副载波复用的新型的多输入单输出(MISO)正交频分复用可见光通信(OFDM-VLC)系统构架,并且实验验证了2×1和3×1的MISO OFDM-VLC系统传输。分别测量了2×1和3×1的实验系统的误差矢量幅度(EVM)随输入电压变化的曲线图,找出了两个系统各自的最佳偏置范围。在将输入电压设置在最佳偏置范围之内的情况下,改变传输距离,对2×1系统,给出了系统EVM性能变化的曲线图;对3×1系统,给出了系统EVM和误码率(BER)性能变化的曲线图。在没有任何均衡的情况下,两个系统的传输距离都可以长达140cm。 相似文献
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《Lightwave Technology, Journal of》2009,27(3):266-272
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The intensity modulation and direct detection (IM/DD) passive optical network (PON) has been demonstrated as a cost-effective solution for a long-reach (\(>\!80\,\hbox {km}\)) access system because it can be easily installed and maintained with low cost and complexity. Meanwhile, orthogonal frequency division multiplexing (OFDM) has been widely used in PONs due to its high spectral efficiency and strong resistance to dispersion impairments. So, the IM/DD OFDM-PON emerged. The power efficiency has attracted great research interests in IM/DD OFDM-PONs. The previous works achieved power savings from the perspective of MAC-layer or hardware-level optimization, but they neglected designing appropriative algorithms, and the long-reach transmission performance cannot be guaranteed. In this paper, we propose an improved Hughes-Hartogs algorithm (IHHA) to adjust the number of bits and power level allocated for each subcarrier, with the objective to minimize the electrical transmitting power of all subcarriers. The OFDM signal is generated according to the bit/power allocation result of IHHA, and we conduct extensive simulations to verify the long-reach transmission performance of our system. Simulation results show that our system has high power efficiency by using IHHA, and bit error rate satisfies the forward error correction limitation after 100 km single-mode fiber transmission. 相似文献
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提出了一种结合 MBE(多带激励 )模型和 LPC(线性预测编码 )模型的 1 .8kbps声码器 .在这种声码器中 ,采用 LPC特征参数来代表语音帧的频谱 ,利用 LPC残差进行基音提取和多带清浊音判决 ,采用 MBE模型合成语音 ,并在高频浊音带的语音合成中混以清音 .在定点 Mo-torola DSP560 0 2 EVM上 ,可以在 1 .8kbps的码率下对语音进行实时的编解码处理 ,具有存储量和计算量较小的特点 .其合成语音质量超过了 LPC- 1 0 e. 相似文献
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Trung-Hien Nguyen Pascal Scalart Mathilde Gay Laurent Bramerie Christophe Peucheret Fausto Gomez-Agis Olivier Sentieys Jean-Claude Simon Michel Joindot 《Photonic Network Communications》2018,36(3):326-337
We report on a simple alternative method for the compensation of quadrature imbalance in optical quadrature phase-shift-keying (QPSK) coherent systems. By introducing a new metric, the phase imbalance can be determined and compensated. The proposed method is theoretically and numerically analyzed. In particular, it is shown that the method exhibits a small bias of estimated phase imbalance value. Thanks to its deterministic property, this bias can be simply compensated by incorporating at the receiver a phase rotator (or phase shift) whose value can be determined based on an analytical analysis. Moreover, the algorithm is also experimentally validated through bit-error-rate and error vector magnitude (EVM) measurements. A good agreement on the performance of the proposed method with that of the Gram–Schmidt orthogonalization procedure is shown in a 20-Gbit/s optical QPSK experiment. The robustness of both methods was verified with up to \(30^\circ \) phase imbalance by comparing the signal with and without phase imbalance compensation. A 10% reduction in EVM is achieved with our method for a high phase imbalance of \(30^\circ \), while the implementation complexity can be reduced owing to the suppression of the use of square-root operators. 相似文献
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Yong-Duck Chung Kwang-Seong Choi Jae-Sik Sim Hyun-Kyu Yu Jeha Kim 《Lightwave Technology, Journal of》2007,25(11):3407-3412
We developed an analog optical system-on-package (SoP) transmitter for a 60-GHz-band radio-over-fiber (RoF) link. The SoP transmitter consisted of an electroabsorption modulator, radio frequency amplifiers, and a bandpass filter. The 60-GHz RoF wireless link was prepared to measure the performance of the SoP transmitter. The transmission characteristics of 64-quadrature amplitude modulation (64-QAM) data of the 60-GHz RoF wireless link, including the SoP transmitter, were investigated by measuring the error vector magnitude (EVM) and signal-to-noise ratio (SNR) with a baseband frequency. The EVM of the 60-GHz RoF wireless link was between 2.25% and 2.80%, and the SNR was between 27.36 and 29.31 dB from 140 and 770 MHz, at input baseband power of -9 dBm. The noise figure had the minimum of 8.44 dB at 500 MHz. We successfully transmitted digital community antenna television (CATV) system signals through the 60-GHz RoF wireless link, including the SoP transmitter. Digital CATV signals of 86 channels could be transmitted through the 60-GHz RoF wireless link, and the total throughput was found to be 2.61 Gb/s. 相似文献
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《Lightwave Technology, Journal of》2009,27(10):1340-1346
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《Lightwave Technology, Journal of》2009,27(10):1279-1285
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基于直流光注入直调DFB-LD的可调光毫米波信号产生技术 总被引:2,自引:2,他引:0
提出了一种基于直流光注入直接调制分布反馈式半导体激光器(DFB-LD)的载波可调的光毫米波生成方案,利用直接调制DFB-LD的输出瞬态波长随驱动电流增大而蓝移的特点,将直流光注入至直调DFB-LD的0码波长附近注入锁定。锁定的直调激光器在1码时输出的蓝移波长与原注入波长相位相干,再通过光电探测器将拍频信号转换为调制的光毫米波信号。实验重点讨论了40GHz光毫米波的产生,同时完成了30、40、50和60GHz光毫米波的可调谐性实验。本文的方案结构简单,无需外调制器和微波本振,载波可调并可产生高至60GHz光毫米波信号,可作为光/无线混合接入中成本节省的光上变频方案。 相似文献
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《Lightwave Technology, Journal of》2009,27(19):4221-4227
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《Solid-State Circuits, IEEE Journal of》2009,44(8):2114-2125