In this article, the peak to average power ratio (PAPR) performance of 8 quadrature amplitude modulation-orthogonal frequency division multiplexing (8QAM-OFDM) optical signals has been researched in broadband optical ...In this article, the peak to average power ratio (PAPR) performance of 8 quadrature amplitude modulation-orthogonal frequency division multiplexing (8QAM-OFDM) optical signals has been researched in broadband optical access system. The complementary cumulative distribution functions (CCDFs) are analyzed of two different 8QAM-OFDMsignals with 16, 32, 64, 128, 256, 512 sub- carriers by simulation. The simulation results show that, with the increase of the number of subcarrier, the PAPR value becomes higher. When the numbers of subcarrier are16 and 512, the PAPR of 8QAM-OFDM optical signals are smaller than 5.2 dB and 5.3 dB respectively. Hence, the number of sub-carriers should be chosen according to practical application.展开更多
正交频分复用(orthogonal frequency division multiplexing,OFDM)技术的关键之一是降低峰均包络功率比。通过把一种新的方形32QAM星座图表示为QPSK和8PSK的线性组合,利用QPSK和8PSK上的格雷序列,用编码方法构造了方形32QAM星座图上的...正交频分复用(orthogonal frequency division multiplexing,OFDM)技术的关键之一是降低峰均包络功率比。通过把一种新的方形32QAM星座图表示为QPSK和8PSK的线性组合,利用QPSK和8PSK上的格雷序列,用编码方法构造了方形32QAM星座图上的一组低峰均包络功率比的序列;证明了对于任意载子波数的32QAM-OFDM通信系统,当输入为新构造序列时,峰均包络功率比不大于4.17(6.2dB)。展开更多
The passive optical network WDM-PON is one of the most dominant performers of all communication systems, and provides sufficient broadband service. Providing enough data for the demands of today and the future, marks ...The passive optical network WDM-PON is one of the most dominant performers of all communication systems, and provides sufficient broadband service. Providing enough data for the demands of today and the future, marks this area as a critical topic for researchers. The first goal of this article is to study the performance of OFDM in a bidirectional WDM-PON by using QAM and BPSK modulation methods in the downstream link. The second goal is to build the upstream link with WBTW-SOA and show its ability to transmit the upstream signal with low equipment. Sending and receiving signals from the central office to the last mile, and opposite of the network up to 100 Km via a bidirectional single mode optical fiber (SMF) was successfully achieved.展开更多
In this paper, the downstream transmission performance of two types of 8QAM-OFDM optical signals in broadband optical access system has been analyzed. After modulation and coding, two types of 10 Gbit/s 8QAM-OFDM opti...In this paper, the downstream transmission performance of two types of 8QAM-OFDM optical signals in broadband optical access system has been analyzed. After modulation and coding, two types of 10 Gbit/s 8QAM-OFDM optical access signals are downstream transmitted over 1 km, 10 km, 20 km and 40 km single mode fibers (SMFs) and received successfully. Different transmission distances impact on the bit error rate (BER) of the received signal is analyzed by simulation, while the signal to noise ratio (SNR) is 20 dB. The results show that, while the transmission distance is shorter than 10 km, the BER values of two types of 8QAM-OFDM optical signals are smaller than 10?10. As the above optical access signals are transmitted over 40 km SMF, the BER value of the first type of 8QAM-OFDM signals is bigger than 10?6, and the BER of the other type of 8QAM-OFDM signals is smaller than 10?6.展开更多
In this paper, the performance of a 60 GHz radio over fiber(Ro F) system with 4/16/64 quadrature amplitude modulation(QAM) orthogonal frequency division multiplexing(OFDM) downstream signals is studied. Delivery of 10...In this paper, the performance of a 60 GHz radio over fiber(Ro F) system with 4/16/64 quadrature amplitude modulation(QAM) orthogonal frequency division multiplexing(OFDM) downstream signals is studied. Delivery of 10 Gbit/s M-ary QAM(MQAM) OFDM signals through the 20-km-long single-mode fiber(SMF) is complicated in terms of intensity modulation and direct detection(IM/DD). Using self-homodyne method, the beating of two independent light waves generating the millimeter-wave at the photodetector can be down-converted to baseband in the electrical domain. Meanwhile, three kinds of sub-carrier arrangement schemes are compared and discussed, and the simulation results show that lower peak-to-average power ratio(PAPR) can be obtained adopting the adjacent scheme. At bit error rate(BER) of 10^(-3), the receiver sensitivity using 4QAM-OFDM sub-carrier signal is almost enhanced by 4 dB and 9 dB compared with those of 16 QAM-OFDM signal and 64 QAM-OFDM signal.展开更多
包络线跟踪电源相较于传统恒压供电大大提高了功放效率,但对硬件要求更高且会产生较高的额外时延。针对以上问题本文提出了一种基于BP神经网络的射频信号包络线的数据预测方案,用于提前生成控制开关变换器的基准信号。首先,基带数据经...包络线跟踪电源相较于传统恒压供电大大提高了功放效率,但对硬件要求更高且会产生较高的额外时延。针对以上问题本文提出了一种基于BP神经网络的射频信号包络线的数据预测方案,用于提前生成控制开关变换器的基准信号。首先,基带数据经正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术生成射频信号的包络线数据。其次,将处理好的数据用于训练包络线跟踪电源的预测模型。最后,改变OFDM调制的子载波数以及选取不同正交振幅调制方式(Quadrature Amplitude Modulation,QAM)分别训练网络。在12子载波下,分别选取16QAM~512QAM之间的6种映射方式进行仿真实验:512QAM在最佳隐含层节点16下训练得到的均方根误差值(Root Mean Squared Error,RMSE)为0.3143;在映射方式为16QAM,64QAM映射方式下,分别选取12、28、52子载波进行仿真,52子载波64QAM映射下的RMSE值最大为0.1752。预测结果中RMSE值均较小,满足预测误差的要求,且预测结果图中包络线与实际包络线拟合效果很好。通过对BP网络预测模型与传统调制模型浮点运算次数的计算,求取52子载波映射方式为64QAM的信号包络,计算次数节省率可以达到49.40%。展开更多
与基于复数域空间正交条件的传统正交频分复用系统(OFDM with Cyclic Prefix,CP-OFDM)有所不同,基于交错正交调制的正交频分复用系统(OFDM/Offset QAM,OFDM/OQAM)满足实数域空间严格正交条件。因此在多径衰落信道条件下,CP-OFDM系统中...与基于复数域空间正交条件的传统正交频分复用系统(OFDM with Cyclic Prefix,CP-OFDM)有所不同,基于交错正交调制的正交频分复用系统(OFDM/Offset QAM,OFDM/OQAM)满足实数域空间严格正交条件。因此在多径衰落信道条件下,CP-OFDM系统中的信道估计方法会导致OFDM/OQAM系统严重的字符间干扰和载波间干扰。该文结合OFDM/OQAM系统结构特点,提出了一种基于迭代信道估计和信号检测算法。该算法通过信道估计器和接收到的信号互相交换信息,消除导频序列中的字符间干扰和载波间干扰,提高信道估计和信号检测的准确度。仿真分析结果表明,经过一定次数迭代处理后,OFDM/OQAM迭代信道估计性能趋近于理想信道估计性能。展开更多
在现有的电力线通信系统(Power Line Communication,PLC)中,正交频分复用(Orthogonal Frequency Divi-sion Multiplex,OFDM)由于能够有效地消除电力线系统中的脉冲噪声干扰、多径时延干扰和群时延干扰,已成为一种主要的技术手段。OFDM...在现有的电力线通信系统(Power Line Communication,PLC)中,正交频分复用(Orthogonal Frequency Divi-sion Multiplex,OFDM)由于能够有效地消除电力线系统中的脉冲噪声干扰、多径时延干扰和群时延干扰,已成为一种主要的技术手段。OFDM技术尽管具有上述优点,但却存在高峰值功率、循环前缀导致的频谱利用率受限等问题。相应地,与OFDM具有不同设计思路的、基于成形滤波器的广义频分复用系统(Generalized Frequency Division Multi-plex,GFDM)也就成为当前研究的热点。GFDM通过设计适合信道时延的成形滤波器,利用其时频聚焦性,可兼有抵抗字符间干扰(Inter Symbol Interference,ISI)和载波间干扰(Inter Carriers Interference,ICI)的能力,并可获得更高的频谱效率(无须循环前缀)。展开更多
在多径衰落信道中,基于交错正交幅度调制的正交频分复用(OFDM with Offset QAM,OFDM/OQAM)系统使用迫零均衡器进行信号检测时,不能完全消除信道复数特性和滤波器实数正交特性引入的时域符号间干扰和频域子载波间干扰,及信道估计误差导...在多径衰落信道中,基于交错正交幅度调制的正交频分复用(OFDM with Offset QAM,OFDM/OQAM)系统使用迫零均衡器进行信号检测时,不能完全消除信道复数特性和滤波器实数正交特性引入的时域符号间干扰和频域子载波间干扰,及信道估计误差导致的误码率性能损失。该文利用对数据初始判决并重构相邻载波及符号间干扰的思想,通过分析采用迫零均衡信号检测时的残余干扰与信道估计误差干扰,提出了一种基于并行干扰抵消和迫零均衡器结合的OFDM/OQAM信号检测方法,并在IEEE 802.22技术标准的两种典型多径衰落信道中进行了计算机仿真与比较研究。仿真结果表明,与基于迫零均衡的检测方法相比,基于并行干扰抵消的迭代信号检测方法在误码率为1%时,可获得1 dB至2 dB的性能提升。展开更多
文摘In this article, the peak to average power ratio (PAPR) performance of 8 quadrature amplitude modulation-orthogonal frequency division multiplexing (8QAM-OFDM) optical signals has been researched in broadband optical access system. The complementary cumulative distribution functions (CCDFs) are analyzed of two different 8QAM-OFDMsignals with 16, 32, 64, 128, 256, 512 sub- carriers by simulation. The simulation results show that, with the increase of the number of subcarrier, the PAPR value becomes higher. When the numbers of subcarrier are16 and 512, the PAPR of 8QAM-OFDM optical signals are smaller than 5.2 dB and 5.3 dB respectively. Hence, the number of sub-carriers should be chosen according to practical application.
文摘正交频分复用(orthogonal frequency division multiplexing,OFDM)技术的关键之一是降低峰均包络功率比。通过把一种新的方形32QAM星座图表示为QPSK和8PSK的线性组合,利用QPSK和8PSK上的格雷序列,用编码方法构造了方形32QAM星座图上的一组低峰均包络功率比的序列;证明了对于任意载子波数的32QAM-OFDM通信系统,当输入为新构造序列时,峰均包络功率比不大于4.17(6.2dB)。
文摘The passive optical network WDM-PON is one of the most dominant performers of all communication systems, and provides sufficient broadband service. Providing enough data for the demands of today and the future, marks this area as a critical topic for researchers. The first goal of this article is to study the performance of OFDM in a bidirectional WDM-PON by using QAM and BPSK modulation methods in the downstream link. The second goal is to build the upstream link with WBTW-SOA and show its ability to transmit the upstream signal with low equipment. Sending and receiving signals from the central office to the last mile, and opposite of the network up to 100 Km via a bidirectional single mode optical fiber (SMF) was successfully achieved.
文摘In this paper, the downstream transmission performance of two types of 8QAM-OFDM optical signals in broadband optical access system has been analyzed. After modulation and coding, two types of 10 Gbit/s 8QAM-OFDM optical access signals are downstream transmitted over 1 km, 10 km, 20 km and 40 km single mode fibers (SMFs) and received successfully. Different transmission distances impact on the bit error rate (BER) of the received signal is analyzed by simulation, while the signal to noise ratio (SNR) is 20 dB. The results show that, while the transmission distance is shorter than 10 km, the BER values of two types of 8QAM-OFDM optical signals are smaller than 10?10. As the above optical access signals are transmitted over 40 km SMF, the BER value of the first type of 8QAM-OFDM signals is bigger than 10?6, and the BER of the other type of 8QAM-OFDM signals is smaller than 10?6.
基金supported by the National Natural Science Foundation of China(No.61107064)the Bayu Scholars Founding,the Chongqing University Innovation Team Founding(No.KJTD201320)+3 种基金the Chongqing Science and Technology Commission Foundation(Nos.cstc2014jcyj A40046,cstc2016jcyj A1233 and cstc2016jcyj A0246)the Chongqing 2011 Collaborative Innovation Center Project(Chongqing Education Department(2016)No.40)the Chongqing Graduate Scientific Research Innovation Project(Nos.CYS15225 and CYS16225)the Science and Technology Special Funds in Wanzhou District
文摘In this paper, the performance of a 60 GHz radio over fiber(Ro F) system with 4/16/64 quadrature amplitude modulation(QAM) orthogonal frequency division multiplexing(OFDM) downstream signals is studied. Delivery of 10 Gbit/s M-ary QAM(MQAM) OFDM signals through the 20-km-long single-mode fiber(SMF) is complicated in terms of intensity modulation and direct detection(IM/DD). Using self-homodyne method, the beating of two independent light waves generating the millimeter-wave at the photodetector can be down-converted to baseband in the electrical domain. Meanwhile, three kinds of sub-carrier arrangement schemes are compared and discussed, and the simulation results show that lower peak-to-average power ratio(PAPR) can be obtained adopting the adjacent scheme. At bit error rate(BER) of 10^(-3), the receiver sensitivity using 4QAM-OFDM sub-carrier signal is almost enhanced by 4 dB and 9 dB compared with those of 16 QAM-OFDM signal and 64 QAM-OFDM signal.
文摘包络线跟踪电源相较于传统恒压供电大大提高了功放效率,但对硬件要求更高且会产生较高的额外时延。针对以上问题本文提出了一种基于BP神经网络的射频信号包络线的数据预测方案,用于提前生成控制开关变换器的基准信号。首先,基带数据经正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术生成射频信号的包络线数据。其次,将处理好的数据用于训练包络线跟踪电源的预测模型。最后,改变OFDM调制的子载波数以及选取不同正交振幅调制方式(Quadrature Amplitude Modulation,QAM)分别训练网络。在12子载波下,分别选取16QAM~512QAM之间的6种映射方式进行仿真实验:512QAM在最佳隐含层节点16下训练得到的均方根误差值(Root Mean Squared Error,RMSE)为0.3143;在映射方式为16QAM,64QAM映射方式下,分别选取12、28、52子载波进行仿真,52子载波64QAM映射下的RMSE值最大为0.1752。预测结果中RMSE值均较小,满足预测误差的要求,且预测结果图中包络线与实际包络线拟合效果很好。通过对BP网络预测模型与传统调制模型浮点运算次数的计算,求取52子载波映射方式为64QAM的信号包络,计算次数节省率可以达到49.40%。
文摘与基于复数域空间正交条件的传统正交频分复用系统(OFDM with Cyclic Prefix,CP-OFDM)有所不同,基于交错正交调制的正交频分复用系统(OFDM/Offset QAM,OFDM/OQAM)满足实数域空间严格正交条件。因此在多径衰落信道条件下,CP-OFDM系统中的信道估计方法会导致OFDM/OQAM系统严重的字符间干扰和载波间干扰。该文结合OFDM/OQAM系统结构特点,提出了一种基于迭代信道估计和信号检测算法。该算法通过信道估计器和接收到的信号互相交换信息,消除导频序列中的字符间干扰和载波间干扰,提高信道估计和信号检测的准确度。仿真分析结果表明,经过一定次数迭代处理后,OFDM/OQAM迭代信道估计性能趋近于理想信道估计性能。
文摘在现有的电力线通信系统(Power Line Communication,PLC)中,正交频分复用(Orthogonal Frequency Divi-sion Multiplex,OFDM)由于能够有效地消除电力线系统中的脉冲噪声干扰、多径时延干扰和群时延干扰,已成为一种主要的技术手段。OFDM技术尽管具有上述优点,但却存在高峰值功率、循环前缀导致的频谱利用率受限等问题。相应地,与OFDM具有不同设计思路的、基于成形滤波器的广义频分复用系统(Generalized Frequency Division Multi-plex,GFDM)也就成为当前研究的热点。GFDM通过设计适合信道时延的成形滤波器,利用其时频聚焦性,可兼有抵抗字符间干扰(Inter Symbol Interference,ISI)和载波间干扰(Inter Carriers Interference,ICI)的能力,并可获得更高的频谱效率(无须循环前缀)。
