Advanced Physics-Based Propagation Models for Channel Characterization in a Wireless Network

9979376 Sarabandi在本提案中，解决了与应用于宽带、高数据速率无线系统的高保真度传播模型开发相关的基础科学问题。 重点放在发展新的方法，获得准确和有效的传播模型所需的字段计算。 发射器和接收器之间的电磁波通过其与其环境的相互作用经历诸如遮蔽、反射、衍射、衰减和多次散射的现象。 先进的、高速的、创新的无线系统的开发需要传播信道的准确知识及其对调制和编码方案、系统带宽、发射机功率和天线设计的影响。 目前的预测方法要么是启发式的，要么过于简单化（基于射线跟踪和简单的衍射模型），往往忽略了对无线电波传播有重大影响的物理现象。 考虑到这一点，提出了一个基于物理的传播预测方法的发展，重点是提供物理现象的基本理解和发展先进的分析和数值电磁（EM）模型。 具体而言，一些现实的典型的几何形状和通用的传播模型的传播块被认为是和详细的计划，用于获取衍射场及其统计准确和有效地提供。 传播问题将被分为三类或环境，每一类都有自己独特的特点，代表农村，城市和大气传播。 在每一个环境电磁散射和衍射现象将进行调查和适当的模型，代表各种环境特征，包括随机变化，将开发和集成。 在每个环境中，将采用分层方法，每一层代表准确预测所需的近似程度。 这些模型最终将与从地理信息系统或遥感技术获得的现有地形数据库结合起来，以产生一种高度准确和通用的预测工具。 对于给定的环境以及发射机和接收机配置，所提出的传播模型将提供平均场强（路径损耗估计）、信号衰落统计、空间去相关距离、频率去相关带宽、移动的平台的多普勒频谱以及信道的时间延迟响应。

9979376SarabandiIn this proposal the basic science issues related to the development of a high fidelity propagation model, for application in wideband, high data rate wireless systems, are addressed. The emphasis is placed on the development of new methodologies for obtaining accurate and efficient field calculations needed for the propagation model. The electromagnetic wave between a transmitter and a receiver, through its interaction with its environment, experiences phenomena such as shadowing, reflection, diffraction, attenuation and multiple scattering. Development of advanced, high speed, innovative wireless systems requires accurate knowledge of the propagation channel and its effects on modulation and coding schemes, system bandwidth, transmitter power and antenna design. Current methods of prediction are either heuristic or overly simplistic (based on ray-tracing and simple diffraction models) and tend to neglect physical phenomena which have a significant effect on radio wave propagation. With this in mind development of a physics-based approach to propagation prediction, with emphasis in providing the basic understanding of the physical phenomena and developing advanced analytical and numerical electromagnetic (EM) models, is proposed. Specifically, a number of realistic canonical geometries and generic propagation blocks for a propagation model are considered and detailed plans for acquiring the diffracted fields and its statistics accurately and efficiently are provided. The propagation problem will be divided into three categories or environments, each of which has its own unique characteristics representing rural, urban, and atmospheric propagation. Within each environment EM scattering and diffraction phenomenon will be investigated and appropriate models, representing various environmental features and including stochastic variations, will be developed and integrated. Within each environment a layered approach will be taken with each layer representing the degree of approximation necessary for accurate prediction. These models will eventually be integrated with existing terrain data bases obtained from geographical information systems (GSI) or remote sensing technology to produce a highly accurate and general prediction tool. For a given environment and transmitter and receiver configurations the proposed propagation model will provide mean-field strength (path loss estimate), signal fading statistics, spatial decorrelation distance, frequency decorrelation bandwidth, Doppler spectrum for mobile platforms, and the time delay response of the channel.***