<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presen...<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10<sup>-3</sup> for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting. </div>展开更多
针对移动终端接入用户和数据的特征难以准确判定,影响移动终端接入控制精准度的问题,提出一种基于EVM(Error Vector Magnitud)测量算法的接入控制技术。考虑到环境中噪声和其他干扰因素影响,以Qos(Quality of Srvice)条件为用户的初始...针对移动终端接入用户和数据的特征难以准确判定,影响移动终端接入控制精准度的问题,提出一种基于EVM(Error Vector Magnitud)测量算法的接入控制技术。考虑到环境中噪声和其他干扰因素影响,以Qos(Quality of Srvice)条件为用户的初始接入条件,计算满足该条件的用户或数据的特征,将特征值转换为权重因子作为接入控制参照。采用EVM测量算法计算终端信道内外信号间的差值,结合用户权重因子推导得到移动终端的接入门限,求解不同用户门限值与控制数值间递增和递减函数,按照函数的优先级顺序,实现移动终端接入的精准控制。实验数据证明,所提方法接入控制精准度高,控制后终端传输时延、阻塞率得到了明显的改善,数据到达率也有明显提升。展开更多
A zero-IF transmitter for Cognitive Radio(CR) application is presented.To effectively reduce the interference between Power Amplifier(PA) and Voltage Controlled Oscillator(VCO),two VCOs are adopted,one is 450 MHz and ...A zero-IF transmitter for Cognitive Radio(CR) application is presented.To effectively reduce the interference between Power Amplifier(PA) and Voltage Controlled Oscillator(VCO),two VCOs are adopted,one is 450 MHz and the other is from 1148 MHz to 1252 MHz with an 8 MHz step,so the frequency of them are different from the operational frequency of PA.The Local Oscillator(LO) of the modulator generated by mixing the signals of the two VCOs has a low phase noise of-82 dBc/Hz with an offset of 1 kHz.The measurement result of the transmitter shows that the Adjacent Channel Power Ratio(ACPR) is less than-47.5 dBc at 27 dBm output,and the Error Vector Magnitude(EVM) is less than 1.7%.展开更多
文摘<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10<sup>-3</sup> for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting. </div>
文摘针对移动终端接入用户和数据的特征难以准确判定,影响移动终端接入控制精准度的问题,提出一种基于EVM(Error Vector Magnitud)测量算法的接入控制技术。考虑到环境中噪声和其他干扰因素影响,以Qos(Quality of Srvice)条件为用户的初始接入条件,计算满足该条件的用户或数据的特征,将特征值转换为权重因子作为接入控制参照。采用EVM测量算法计算终端信道内外信号间的差值,结合用户权重因子推导得到移动终端的接入门限,求解不同用户门限值与控制数值间递增和递减函数,按照函数的优先级顺序,实现移动终端接入的精准控制。实验数据证明,所提方法接入控制精准度高,控制后终端传输时延、阻塞率得到了明显的改善,数据到达率也有明显提升。
基金Supported by the National High-Tech Project (No. 2009AA011801)National Natural Science Foundation of China (No. 60621002)
文摘A zero-IF transmitter for Cognitive Radio(CR) application is presented.To effectively reduce the interference between Power Amplifier(PA) and Voltage Controlled Oscillator(VCO),two VCOs are adopted,one is 450 MHz and the other is from 1148 MHz to 1252 MHz with an 8 MHz step,so the frequency of them are different from the operational frequency of PA.The Local Oscillator(LO) of the modulator generated by mixing the signals of the two VCOs has a low phase noise of-82 dBc/Hz with an offset of 1 kHz.The measurement result of the transmitter shows that the Adjacent Channel Power Ratio(ACPR) is less than-47.5 dBc at 27 dBm output,and the Error Vector Magnitude(EVM) is less than 1.7%.
