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

9979376 sarabandii在本提案中讨论了与开发用于宽带、高数据速率无线系统的高保真传播模型相关的基础科学问题。重点是发展新的方法，以获得传播模型所需的准确和有效的现场计算。发射器和接收器之间的电磁波，通过与环境的相互作用，经历了阴影、反射、衍射、衰减和多重散射等现象。开发先进、高速、创新的无线系统需要准确了解传播信道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（基于射线追踪和简单的衍射模型），往往忽视对无线电波传播有重大影响的物理现象。考虑到这一点，提出了一种基于物理的传播预测方法，重点是提供对物理现象的基本理解，并开发先进的分析和数值电磁（EM）模型。具体地说，考虑了一些现实的正则几何形状和传播模型的一般传播块，并提供了准确有效地获取衍射场及其统计信息的详细计划。传播问题将被分为三类或环境，每一类或环境都有自己独特的特征，分别代表农村、城市和大气传播。在每个环境中，将研究EM散射和衍射现象，并开发和集成适当的模型，代表各种环境特征，包括随机变化。在每个环境中，将采用分层方法，每一层表示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（GSI）或遥感技术获得的现有地形数据库相结合，以产生高度准确和普遍的预测工具。对于给定的环境和发射器和接收器配置，所提出的传播模型将提供平均场强度（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、移动平台的多普勒频谱和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.***