提出了一种适用于3GPP长期演进(Long Term Evolution,LTE)系统上行链路的信道估计算法。为了降低抑制噪声过程中信道能量的损失,该算法对最小二乘(Least Square,LS)算法的时域结果采用从中间向两端搜索的方式进行能量检测。仿真结果表明,该算法与LS算法、传统的基于DFT的估计算法、线性最小均方误差(Linear Minimum Mean Square Error,LMMSE)算法及负指数LMMSE算法相比,性能良好,且易于实现,具有很好的实用性。
该文提出了一种基于不等长时隙的射频识别(Radio Frequency Identification,RFID)动态帧时隙ALOHA(Dynamic Framed-Slotted ALOHA,DFSA)防碰撞算法。算法考虑到大量碰撞时隙和空闲时隙对系统效率的影响,采用帧内时隙长度不等的优化策略,由时隙优化参数和未读标签数确定帧长,通过优化的切比雪夫不等式法进行标签估计,并基于马尔科夫链分析标签识别过程,来实现读取周期的控制。分析和仿真结果表明,该算法比时隙优化前的DFSA算法效率更高,平均识别时间更短,标签数估计比下限值法、Schoute法和碰撞率法更准确。
By using the variational Lyapunov method and Razumikhin technique, the stability criteria in terms of two measures for impulsive delay differential systems are established. The known results are generalized and improved. An example is worked out to illustrate the advantages of the theorems.
Kai En LIU1,2, Guo Wei YANG3 1. School of Mathematics, Qingdao University, Shandong 266071, P. R. China
