DOA估计:古典与现代方法探索

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"Classical and Modern DOA Estimation" 本书《Classical and Modern DOA Estimation》是2009年由Elsevier出版的一部专注于方向-of-arrival (DOA)估计技术的专业文献,它集合了在Elsevier数据上发表的相关论文,为读者提供了丰富的DOA估计算法和理论知识。DOA估计是信号处理领域的一个关键问题,特别是在无线通信、雷达系统和声学传感器网络中,用于确定信号源相对于接收阵列的方向。 DOA估计算法主要包括经典方法和现代方法。经典方法通常涉及数学统计和矩阵理论,如最大似然(ML)估计、最小二乘(LS)估计和音乐算法(MUSIC)。这些方法基于阵列信号处理,利用多通道接收信号之间的相位差来确定信号源的方向。例如,最大似然估计通过寻找最可能产生观测数据的信号源方向来估计DOA,而音乐算法则利用特征值分解来识别噪声子空间,从而估计信号源的方向。 现代DOA估计技术则涵盖了更广泛的领域,包括阵列信号处理的高级理论、机器学习和人工智能算法。例如,基于稀疏表示的DOA估计利用信号的稀疏特性来提高估计精度,这在噪声环境复杂的情况下特别有效。此外,现代方法还包括利用神经网络和深度学习的方法,通过训练模型来直接预测DOA,这种方法可以自动学习信号特性和阵列配置的复杂关系,进一步提升DOA估计的性能。 书中可能还探讨了阵列几何结构的影响,如线性阵列、圆阵列和随机分布阵列等,以及各种阵列处理技术,如波束形成、自适应滤波和空间谱估计。每种阵列结构都有其特定的优势和适用场景,如线性阵列适用于平面波入射,而圆阵列可以提供全方位的覆盖。 除了理论分析外,本书可能还包含实际应用案例和实验结果,以展示不同DOA估计方法在真实世界情境中的表现。这有助于读者理解如何选择合适的DOA估计技术,并将其应用于实际系统设计中。 此外,版权信息提醒读者,本书内容受到严格保护,未经许可不得复制或传播。如果需要使用其中的内容,应事先获得出版社的授权。读者可以通过Elsevier的官方网站获取权限申请相关信息。 《Classical and Modern DOA Estimation》是了解和深入研究DOA估计技术的重要参考资料,无论对于学术研究者还是工程实践者,都能从中获益良多。

Please revise the paper:Accurate determination of bathymetric data in the shallow water zone over time and space is of increasing significance for navigation safety, monitoring of sea-level uplift, coastal areas management, and marine transportation. Satellite-derived bathymetry (SDB) is widely accepted as an effective alternative to conventional acoustics measurements over coastal areas with high spatial and temporal resolution combined with extensive repetitive coverage. Numerous empirical SDB approaches in previous works are unsuitable for precision bathymetry mapping in various scenarios, owing to the assumption of homogeneous bottom over the whole region, as well as the limitations of constructing global mapping relationships between water depth and blue-green reflectance takes no account of various confounding factors of radiance attenuation such as turbidity. To address the assumption failure of uniform bottom conditions and imperfect consideration of influence factors on the performance of the SDB model, this work proposes a bottom-type adaptive-based SDB approach (BA-SDB) to obtain accurate depth estimation over different sediments. The bottom type can be adaptively segmented by clustering based on bottom reflectance. For each sediment category, a PSO-LightGBM algorithm for depth derivation considering multiple influencing factors is driven to adaptively select the optimal influence factors and model parameters simultaneously. Water turbidity features beyond the traditional impact factors are incorporated in these regression models. Compared with log-ratio, multi-band and classical machine learning methods, the new approach produced the most accurate results with RMSE value is 0.85 m, in terms of different sediments and water depths combined with in-situ observations of airborne laser bathymetry and multi-beam echo sounder.

2023-02-18 上传

Unlike the classical encryption schemes,keys are dispensable in certain PLS technigues, known as the keyless secure strat egy. Sophisticated signal processing techniques such as arti- ficial noise, beamforming,and diversitycan be developed to ensure the secrecy of the MC networks.In the Alice-Bob-Eve model, Alice is the legitimate transmitter, whose intended target is the legitimate receiver Bob,while Eve is the eavesdropper that intercepts the information from Alice to Bob.The secrecy performance is quantified via information leakagei.ethe dif ference of the mutual information between the Alice-Bob and Alice-Eve links. The upper bound of the information leakage is called secrecy capacity realized by a specific distribution of the input symbols, namely,capacity-achieving distribution.The secrecy performance of the diffusion-based MC system with concentration shift keying(CSK)is analyzed from an informa- tion-theoretical point of view,providing two paramount secrecy metrics, i.e., secrecy capacity and secure distance[13].How ever, only the estimation of lower bound secrecy capacity is derived as both links attain their channel capacity.The secrecy capacity highly depends on the system parameters such as the average signal energy,diffusion coefficientand reception duration. Moreover, the distance between the transmitter and the eavesdropper is also an important aspect of secrecy per- formance. For both amplitude and energy detection schemes secure distance is proposed as a secret metricover which the eavesdropper is incapable of signal recovery. Despite the case with CSK,the results of the secure metrics vary with the modulation type(e.g.pulse position,spacetype) and reception mechanism(e.g.passive,partially absorbingper fectly absorbing).For ease of understanding,Figure 3 depicts the modulation types and the corresponding CIRs with different reception mechanisms. Novel signa processing techniques and the biochemical channel properties can further assist the secrecy enhancement in the MC system.The molecular beam forming that avoids information disclosure can be realized via the flow generated in the channel.Besidesnew dimensions of diversity, such as the aforementioned molecular diversity of ionic compounds, can beexploited. Note that the feasibility of these methods can be validated by the derived secrecy metrics.

2023-06-13 上传