SC-FDMA系统中基于统计压扩的峰均功率比减小方法

为了减小单载波频分多址接入系统(SC-FDMA)的峰均功率比(PAPR),提出了基于统计压扩的新方法.该方法的原理是将SC-FDMA系统发射信号的统计特性和压扩技术结合起来.研究结果表明:新方法不但能将SC-FDMA系统的PAPR减小到2 dB左右,而且可以将系统的误码率降至原来的1/4,从而更好地满足LTE标准化的需求.     

X射线荧光光谱测定铅锑合金中9种元素

以铅锑合金作为光谱标样,用理论α系数及干扰曲线法进行基体效应和谱线重叠干扰的校正,建立了X射线荧光光谱测定铅锑合金中锑、锡、银、铜、铋、砷、锌、镉、镍9种元素的检测方法。用该方法测定铅锑标准样品,其测试结果与标准值基本相符,11次制样测定,各元素SD均小于0.05%。     

Blind channel estimation through redundant linear precoding for OFDM systems

A novel approach of blind channel estimation through redundant linear precoding for orthogonal fre-quency-division multiplexing （OFDM） is proposed. A redundant linear frequency-domain preceder is ap-plied to each pair of blocks before they enter the OFDM system. With the aid of the introduced structure, the frequency-selective channel can be identified at the receiver through auto-correlation operations, sin-gular value decomposition （SVD） and scalar ambiguity resolution. The proposed blind channel estimation method has low computation complexity and requires no prior statistical information of channel or noise. The redundant linear frequency-domain precoder is employed to identify the frequency-selective fading channels. And the proposed blind channel estimation method has high spectral efficiency because it re-quires no training sequence. Computer simulations have proved that this proposed blind channel estima- tion method can identify the frequency-selective channels perfectly and have a good performance.