In order to exploit the capability of the peak-to-average power ratio（PAPR）reduction afforded by the partial transmit sequences （PTS）approach in orthogonal frequency division multiplexing（OFDM）systems, subblock ...In order to exploit the capability of the peak-to-average power ratio（PAPR）reduction afforded by the partial transmit sequences （PTS）approach in orthogonal frequency division multiplexing（OFDM）systems, subblock partition schemes for the PTS approach are studied. The motivation is to establish the relationship between the subblock partition and the capability of PAPR reduction through the periodic autocorrelation functions （ACFs）of partial transmit sequences and the periodic cross-correlation functions（CCFs）of signal candidates.Let Q represent the variation of the square magnitudes of ACFs.It is found that the lower the Q-value is, the better PAPR performance can be achieved, which is introduced as a design criterion for subblock partition.Based on this criterion, four common partition methods are compared and an efficient partition strategy is proposed. It is shown that structured partition schemes with low computational complexity have a large Q-value, leading to a poor PAPR performance.The new strategy can be regarded as a trade-off between PAPR performance and computational complexity.The simulation results show that the strategy can achieve an optimal performance with a relatively low complexity and, moreover,does not increase the amount of side information.展开更多
In this article, an inter-antenna inter-subblock shifting and inversion （IASSI） scheme is proposed to reduce the peak-to-average power ratio （PAPR） in multi-input multioutput orthogonal frequency division multiple...In this article, an inter-antenna inter-subblock shifting and inversion （IASSI） scheme is proposed to reduce the peak-to-average power ratio （PAPR） in multi-input multioutput orthogonal frequency division multiplexing （MIMO- OFDM） systems. It exploits multiple antennas and subblocks to provide additional degrees of freedom to benefit the system. To reduce the implementation complexity of the proposed scheme, two simple suboptimal schemes are further presented based on the minimum current maximum criterion; one adopts sequential search and the other employs random binary grouping. The simulation results exhibit the effectiveness of these proposed schemes.展开更多
通过对不同参数下CLAHE算法处理结果得到的图像熵曲线和主观质量的观察来确定最佳的图像CLAHE处理参数选择.采用平均强度、图像熵和均方根对比度来对图像结果分析.大雾图像和动物图像处理结果表明CLAHE优于直方图均衡化算法(HE),信息熵...通过对不同参数下CLAHE算法处理结果得到的图像熵曲线和主观质量的观察来确定最佳的图像CLAHE处理参数选择.采用平均强度、图像熵和均方根对比度来对图像结果分析.大雾图像和动物图像处理结果表明CLAHE优于直方图均衡化算法(HE),信息熵分别为7.37 vs 6.96和6.69 vs 5.5;同时CLAHE算法还避免了因灰度聚集的过暗区域拉伸造成图像细节丢失的问题.不同类型图像分析表明用图像熵来确定CLAHE参数的方法能获得较好的图像处理效果,用较低对比度改变了图像.展开更多
文摘In order to exploit the capability of the peak-to-average power ratio（PAPR）reduction afforded by the partial transmit sequences （PTS）approach in orthogonal frequency division multiplexing（OFDM）systems, subblock partition schemes for the PTS approach are studied. The motivation is to establish the relationship between the subblock partition and the capability of PAPR reduction through the periodic autocorrelation functions （ACFs）of partial transmit sequences and the periodic cross-correlation functions（CCFs）of signal candidates.Let Q represent the variation of the square magnitudes of ACFs.It is found that the lower the Q-value is, the better PAPR performance can be achieved, which is introduced as a design criterion for subblock partition.Based on this criterion, four common partition methods are compared and an efficient partition strategy is proposed. It is shown that structured partition schemes with low computational complexity have a large Q-value, leading to a poor PAPR performance.The new strategy can be regarded as a trade-off between PAPR performance and computational complexity.The simulation results show that the strategy can achieve an optimal performance with a relatively low complexity and, moreover,does not increase the amount of side information.
基金the National Natural Science Foundation of China（NSFC 60496312）；the Hi-Tech Research and Development Program of China（2006AA01Z260）；KDDI company of Japan.
文摘In this article, an inter-antenna inter-subblock shifting and inversion （IASSI） scheme is proposed to reduce the peak-to-average power ratio （PAPR） in multi-input multioutput orthogonal frequency division multiplexing （MIMO- OFDM） systems. It exploits multiple antennas and subblocks to provide additional degrees of freedom to benefit the system. To reduce the implementation complexity of the proposed scheme, two simple suboptimal schemes are further presented based on the minimum current maximum criterion; one adopts sequential search and the other employs random binary grouping. The simulation results exhibit the effectiveness of these proposed schemes.
文摘通过对不同参数下CLAHE算法处理结果得到的图像熵曲线和主观质量的观察来确定最佳的图像CLAHE处理参数选择.采用平均强度、图像熵和均方根对比度来对图像结果分析.大雾图像和动物图像处理结果表明CLAHE优于直方图均衡化算法(HE),信息熵分别为7.37 vs 6.96和6.69 vs 5.5;同时CLAHE算法还避免了因灰度聚集的过暗区域拉伸造成图像细节丢失的问题.不同类型图像分析表明用图像熵来确定CLAHE参数的方法能获得较好的图像处理效果,用较低对比度改变了图像.
