压缩传感：水声信道估计中的过完备字典优化设计

Compressed Sensing (CS) offers a method to solve the channel estimation problems for an underwater acoustic system, based on the existence of a sparse representation of the treated signal and an overcomplete dictionary with a set of non-orthogonal bases. In this paper, we proposed a new approach to optimize dictionaries by decreasing the average measure of the mutual coherence of the effective dictionary. A fixed link between the average mutual coherence and the CS performance is indicated by designing three factors : operating bandwidth, the number of pilot subcarriers, and coherence bandwidth. Both the Orthogonal Matching Pursuit (OMP) and the Basis Pursuit De-Noising (BPDN) are compared to the Dantzig Selector (DS) for different Signal Noise Ratio (SNR) and shown to benefit from the newly designed dictionary. Numerical simulations and experimental data of an OFDM receiver are used to evaluate the proposed method in comparison with the conventional Least-Square (LS) estimator. The results show that the dictionary with a better condition considerably improves the performance of the channel estimation.     

“信号与系统”课程分级式案例教学模式

摘要：为了充分践行新工科教育教学理念,电气类专业课“信号与系统”课程建设需要从课程内部知识点间强关联出发,并与工程实践配合。针对该问题,对基于知识图谱与分级式复杂工程案例的“信号与系统”课程教学模式进行了研究,并开发同步大作业案例平台,将“信号与系统”课程中知识点谱系、教学案例、教学平台与工程问题深度融合。通过教学实践表明,该教学模式可以提高学生的高阶思维和创新思维能力,并对课程建设提供有力支撑。     

基于压缩感知的超宽带信道估计方法的研究

压缩感知(Compressed Sensing, CS)理论可以从较少的观测样本中恢复稀疏信号。针对超宽带(Ultra- WideBand, UWB)信道的稀疏特性,将压缩感知理论应用于UWB系统的信道估计中,能够有效地降低系统的采样速率。该文针对UWB信道的特点对过完备字典库和观测矩阵进行设计,提出了一种滤波矩阵估计算法。然后,分别利用丹茨格选择器(Dantzig Selector, DS),基追踪降噪(Basis Pursuit De-Noising, BPDN)算法和正交匹配跟踪(Orthogonal Matching Pursuit, OMP)算法实现信号检测,进一步给出UWB信道估计中CS重建算法的选择建议。基于IEEE 802.15.4a信道模型的仿真结果表明,该算法同随机观测算法的检测结果相比,能够在较低的采样速率下获得更好的误码率性能。     

“互联网+多层次”视角下“信号与系统”课程案例教学模式研究

在“互联网+”和学科建设工程化的背景下,针对培养具有工程实践能力、团队合作精神和创新素质人才的目标,对“信号与系统”课程进行多层次的探索性改革,构建了“互联网+多层次”案例教学模式。文章结合超星学习通平台和案例设计,全面提升该课程的教学效果,并给出多层次评价体系。实践结果表明,该教学模式能在增加学生参与度和学习兴趣的同时,使课程目标达成度有明显提高。