A high accuracy frequency synchronization method is proposed for the 3rd generation partnership project （3GPP） long term evolution advanced （LTE-A） downlink receiver in time division duplexing （TDD） mode. In general, cyclic prefix （CP） correlation based fractional frequency offset （FFO） estimation method and primary synchronization signal （PSS） differential correlation based integer frequency offset （IFO） estimation method are applied for LTE-A frequency synchronization. However, the polarity of CP based FFO estimation result may get reversed when system FFO is closer to the edge of frequency estimation range on account of noise interference; PSS based IFO estimation has performance degradation in low signal noise ratio （SNR）. We propose polarity detection aided CP based FFO estimation and frequency domain enhanced differential correlation based IFO estimation to obtain higher accuracy of frequency synchronization. Computer simulation shows that the proposed method greatly outperforms the conventional methods, especially in low SNR scenario.
在无线传感器网络(wireless sensor network,WSN)中P,如何解决漏斗效应、有效平衡节点的能量分布,是延长网络生存时间的关键问题.针对漏斗效应提出一种基于低功耗自适应集簇分层型(1ow energy adaptive clusteringhierarchy,LEACH)协议的改进簇首控制算法(cluster control based on LEACH,CC-LEACH),通过sink辅助选择簇首分布.仿真证明,这种新型簇首选择机制能更好地进行能量均衡,延长网络生命周期.
