To obtain good trade-offs between complexity and performance onpeak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM)using partial transmitting sequence (PTS) schemes, a trel...To obtain good trade-offs between complexity and performance onpeak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM)using partial transmitting sequence (PTS) schemes, a trellis structure based PTS factor searchmethod is proposed. The trellis search is with a variant constraint length L_C, 1 ≤ L_C ≤ V-1,where V is the number of PTS subblocks. The method is to decide a PTS factor by searching all thepossible paths obtained by varying L_C consecutive factors. The trellis search can be viewed as ageneral PTS factor search model. If L_C = V-1, it is a full search, and if L_C = 1, it is aniterative search. Using different constraint lengths, trellis factor search PTS exhibits differentPAPR reduction performances. A larger L_C results in a better performance and L_C = V-1 results inthe optimum. However, a larger L_C requires more computation. This helps to choose a good trade-offbetween complexity and performance.展开更多
This paper deals with channel estimation for orthogonal frequency-division multiplexing (OFDM) systems with transmit diversity. Space time coded OFDM systems, which can provide transmit diversity, require perfect chan...This paper deals with channel estimation for orthogonal frequency-division multiplexing (OFDM) systems with transmit diversity. Space time coded OFDM systems, which can provide transmit diversity, require perfect channel estimation to improve communication quality. In actual OFDM systems, training sequences are usually used for channel estimation. The authors propose a training based channel estimation strategy suitable for space time coded OFDM systems. This novel strategy provides enhanced performance, high spectrum efficiency and relatively low computation complexity.展开更多
Partial transmit sequence (PTS) is a promising technique for peak-to-average power ratio (PAPR) re-duction in orthogonal frequency division multiplexing (OFDM). While in optimal PTS, an exhaustive search for all combi...Partial transmit sequence (PTS) is a promising technique for peak-to-average power ratio (PAPR) re-duction in orthogonal frequency division multiplexing (OFDM). While in optimal PTS, an exhaustive search for all combinations of phase factor sequences is required, this results in huge computation. In this paper, by introducing the orthogonal design, a phase factor sequences algorithm is proposed. The algorithm uses orthogonal table to gen-erate phase factor sequences, and the regular PAPR computation result is then followed by the parameter estima-tion. The simulation result shows that the proposed algorithm reduces the computation notably and obtains a good PAPR performance approaching the optimal PTS.展开更多
In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship...In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio（PAPR）. Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.展开更多
针对在水下无线光通信(Underwater Wireless Optical Communication,UWOC)中使用直流偏置光正交频分复用(Direct Current Optical-Orthogonal Frequency Division Multiplexing,DCOOFDM)技术导致的峰均比(Peak-to-Average Power Ratio,P...针对在水下无线光通信(Underwater Wireless Optical Communication,UWOC)中使用直流偏置光正交频分复用(Direct Current Optical-Orthogonal Frequency Division Multiplexing,DCOOFDM)技术导致的峰均比(Peak-to-Average Power Ratio,PAPR)过高的问题,基于部分传输序列(Partial Transmit Sequence,PTS)方法,使用粒子群优化-遗传因子算法(Partial Swarm Optimization-Genetic Algorithm,PSO-GA)联合算法寻找最佳相位因子,以降低PAPR。仿真结果表明,使用联合算法寻找最佳相位因子,在互补累积分布函数(Complementary Cumulative Distribution Function,CCDF)为10-4时,可以使得系统的峰均比降低约3 dB。相较于传统PTS算法与限幅算法,PSO-GA算法在保证PAPR性能改善的前提下,没有牺牲误码率性能。展开更多
Three virus-infected Carica papaya samples showing mosaic,leaf roll symptoms and three virus-infected Hibiscus rosa-sinensis samples showing chlorosis and distortion symptoms were collected in Danzhou of Hainan Provin...Three virus-infected Carica papaya samples showing mosaic,leaf roll symptoms and three virus-infected Hibiscus rosa-sinensis samples showing chlorosis and distortion symptoms were collected in Danzhou of Hainan Province.A pair of degenerate primers was designed according to the conserved sequence of CP gene and intergenic spacer of Whitefly-transmittal geminiviruses(WTGV),PCR product of expected size was amplified from six samples.The specific fragments were cloned and sequenced,and sequence analysis showed that PCR product had a geminiviral gene origin,which was demonstrated by BLAST.Partial DNA-A between P1 and H2 shared only 66% nucleotide sequence identity.Polygenie analysis with DNA-A of P1 and H2 from other 16 WTG,P1 was most closely related to LAYVV,H2 differed from those of other geminiviruses and constitute a new evolutionary branch.展开更多
为了降低多输入多输出正交频分复用(multiple input multiple output orthogonal frequency division multiplexing,MIMO-OFDM)系统中传统部分传输序列(partial transmit sequence,PTS)算法的计算复杂度,提出了联合时域和空间域信号处...为了降低多输入多输出正交频分复用(multiple input multiple output orthogonal frequency division multiplexing,MIMO-OFDM)系统中传统部分传输序列(partial transmit sequence,PTS)算法的计算复杂度,提出了联合时域和空间域信号处理的改进PTS算法。在时域信号处理部分,通过信号子块循环移位实现备选序列的增加;在空间域部分,利用天线间信号子块交换实现峰均功率比(peak to average power ratio,PAPR)抑制。同时在接收端,利用子块相位旋转引起的相位差异,本方法通过比较接收信号与星座点的距离,可以实现信号的盲检测,从而有效提高MIMO-OFDM系统的频谱利用率。仿真结果表明,提出的方法能有效地抑制MIMO-OFDM信号的PAPR,而且明显降低了传统PTS算法的计算复杂度,同时可获得跟传统PTS方法已知边带副信息时相似的比特误码率(bit error rate,BER)性能。展开更多
From the conserved regions of the reported nucleotide sequences of whitefly-transmitted geminiviruses (WTGV), a pair of degenerate primers was designed to anneal to the conserved sequence. The tomato samples infected ...From the conserved regions of the reported nucleotide sequences of whitefly-transmitted geminiviruses (WTGV), a pair of degenerate primers was designed to anneal to the conserved sequence. The tomato samples infected geminivirus-like from Guangdong were detected by PCR. The results showed that a 356bp specific fragment was amplified from the samples. The specific fragment was cloned and sequenced, and the sequence was compared with all nucleotide sequences in GenBank by Blast of NCBI. The result showed that the fragment belonged to Geminiviridae DNA. So the degenerate primers may be used to detect the WTGV from tomato in Guangdong. Moreover, both of the homology of the fragment between WTGV from tomato in Guangdong and the reported WTGV in the world and WTGV from tomato in Guangxi were under 82%. These results implied that the WTGV from tomato in Guangdong differed from the above-mentioned WTGV.展开更多
文摘To obtain good trade-offs between complexity and performance onpeak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM)using partial transmitting sequence (PTS) schemes, a trellis structure based PTS factor searchmethod is proposed. The trellis search is with a variant constraint length L_C, 1 ≤ L_C ≤ V-1,where V is the number of PTS subblocks. The method is to decide a PTS factor by searching all thepossible paths obtained by varying L_C consecutive factors. The trellis search can be viewed as ageneral PTS factor search model. If L_C = V-1, it is a full search, and if L_C = 1, it is aniterative search. Using different constraint lengths, trellis factor search PTS exhibits differentPAPR reduction performances. A larger L_C results in a better performance and L_C = V-1 results inthe optimum. However, a larger L_C requires more computation. This helps to choose a good trade-offbetween complexity and performance.
基金Project supported by the Hi-Tech Research and Development Pro-gram (863) of China (No. 2003AA123310) and the National Natural Science Foundation of China (No. 60332030)
文摘This paper deals with channel estimation for orthogonal frequency-division multiplexing (OFDM) systems with transmit diversity. Space time coded OFDM systems, which can provide transmit diversity, require perfect channel estimation to improve communication quality. In actual OFDM systems, training sequences are usually used for channel estimation. The authors propose a training based channel estimation strategy suitable for space time coded OFDM systems. This novel strategy provides enhanced performance, high spectrum efficiency and relatively low computation complexity.
基金Supported by Tianjin Natural Science Foundation (No. 043600611)Key Scientific and Technological Training Program of Tianjin (No. 043102911).
文摘Partial transmit sequence (PTS) is a promising technique for peak-to-average power ratio (PAPR) re-duction in orthogonal frequency division multiplexing (OFDM). While in optimal PTS, an exhaustive search for all combinations of phase factor sequences is required, this results in huge computation. In this paper, by introducing the orthogonal design, a phase factor sequences algorithm is proposed. The algorithm uses orthogonal table to gen-erate phase factor sequences, and the regular PAPR computation result is then followed by the parameter estima-tion. The simulation result shows that the proposed algorithm reduces the computation notably and obtains a good PAPR performance approaching the optimal PTS.
基金supported by the National Natural Science Foundation of China(6167309361370152)the Science and Technology Project of Shenyang(F16-205-1-01)
文摘In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio（PAPR）. Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.
文摘针对在水下无线光通信(Underwater Wireless Optical Communication,UWOC)中使用直流偏置光正交频分复用(Direct Current Optical-Orthogonal Frequency Division Multiplexing,DCOOFDM)技术导致的峰均比(Peak-to-Average Power Ratio,PAPR)过高的问题,基于部分传输序列(Partial Transmit Sequence,PTS)方法,使用粒子群优化-遗传因子算法(Partial Swarm Optimization-Genetic Algorithm,PSO-GA)联合算法寻找最佳相位因子,以降低PAPR。仿真结果表明,使用联合算法寻找最佳相位因子,在互补累积分布函数(Complementary Cumulative Distribution Function,CCDF)为10-4时,可以使得系统的峰均比降低约3 dB。相较于传统PTS算法与限幅算法,PSO-GA算法在保证PAPR性能改善的前提下,没有牺牲误码率性能。
文摘Three virus-infected Carica papaya samples showing mosaic,leaf roll symptoms and three virus-infected Hibiscus rosa-sinensis samples showing chlorosis and distortion symptoms were collected in Danzhou of Hainan Province.A pair of degenerate primers was designed according to the conserved sequence of CP gene and intergenic spacer of Whitefly-transmittal geminiviruses(WTGV),PCR product of expected size was amplified from six samples.The specific fragments were cloned and sequenced,and sequence analysis showed that PCR product had a geminiviral gene origin,which was demonstrated by BLAST.Partial DNA-A between P1 and H2 shared only 66% nucleotide sequence identity.Polygenie analysis with DNA-A of P1 and H2 from other 16 WTG,P1 was most closely related to LAYVV,H2 differed from those of other geminiviruses and constitute a new evolutionary branch.
文摘为了降低多输入多输出正交频分复用(multiple input multiple output orthogonal frequency division multiplexing,MIMO-OFDM)系统中传统部分传输序列(partial transmit sequence,PTS)算法的计算复杂度,提出了联合时域和空间域信号处理的改进PTS算法。在时域信号处理部分,通过信号子块循环移位实现备选序列的增加;在空间域部分,利用天线间信号子块交换实现峰均功率比(peak to average power ratio,PAPR)抑制。同时在接收端,利用子块相位旋转引起的相位差异,本方法通过比较接收信号与星座点的距离,可以实现信号的盲检测,从而有效提高MIMO-OFDM系统的频谱利用率。仿真结果表明,提出的方法能有效地抑制MIMO-OFDM信号的PAPR,而且明显降低了传统PTS算法的计算复杂度,同时可获得跟传统PTS方法已知边带副信息时相似的比特误码率(bit error rate,BER)性能。
文摘From the conserved regions of the reported nucleotide sequences of whitefly-transmitted geminiviruses (WTGV), a pair of degenerate primers was designed to anneal to the conserved sequence. The tomato samples infected geminivirus-like from Guangdong were detected by PCR. The results showed that a 356bp specific fragment was amplified from the samples. The specific fragment was cloned and sequenced, and the sequence was compared with all nucleotide sequences in GenBank by Blast of NCBI. The result showed that the fragment belonged to Geminiviridae DNA. So the degenerate primers may be used to detect the WTGV from tomato in Guangdong. Moreover, both of the homology of the fragment between WTGV from tomato in Guangdong and the reported WTGV in the world and WTGV from tomato in Guangxi were under 82%. These results implied that the WTGV from tomato in Guangdong differed from the above-mentioned WTGV.
