CIF: Medium: Modeling, Analysis, and Code Design for Portable Wireless Device Transmitters Subject to an Electromagnetic Exposure Constraint

全球销售的便携式无线设备有数十亿台，它们每天都在使用，因为它们能够通过将处理能力、触摸屏、相机和运动传感器与多个无线电集成在一起来提供连接，其中许多无线电可以同时运行。在人体附近使用的便携式无线设备具有发射功率限制，这在很大程度上是由一种名为比吸收率(SAR)的电磁暴露形式的监管限制决定的。SAR以每公斤瓦特为单位测量，是人体吸收电磁能量的速率的衡量标准。今天销售的许多便携式无线设备工作在可接受的人类SAR极限附近。这项研究考察了在受合成孔径雷达约束的情况下，如何对便携式无线设备上的多个发射机进行建模、分析和使用。这项工作着眼于如何对约束进行建模，以及如何实现受约束的多个天线的可靠性和高数据速率优势。由于便携式设备通常很小，发射机将在物理上彼此接近并进行电磁耦合。因此，这项研究需要在三个不同的领域进行混合工作：(I)多发射机的电磁学和近场暴露建模，(Ii)近场SAR约束下的无线通信系统远场信息理论性能评估，(Iii)优化性能的SAR码的设计。编码性能将通过模拟和实验室评估来确定，用于近场合成孔径雷达和远场误码率测量的微波设备。

Portable wireless devices sold around the world number in the billions, andthey are used daily because of their ability to provide connectivity byintegrating processing power, touch screens, cameras, and motion sensorswith multiple radios, many of which can run simultaneously. Portablewireless devices used in close proximity to the human body have transmitterpower constraints that are dictated largely by regulatory limits on a formof electromagnetic exposure called ``specific absorption rate'' (SAR).SAR, measured in Watts per kilogram, is a measure of the rate ofelectromagnetic energy absorption by the body. Many portable wirelessdevices sold today operate near the accepted human SAR limit. Thisresearch examines how multiple transmitters on a portable wireless devicecan be modeled, analyzed, and used while subject to a SAR constraint. Thework looks at how to model the constraint, and how to realize thereliability and high data-rate advantages of multiple antennas subject tothe constraint.Because portable devices are generally small, transmitters will bephysically close to one another and couple electromagnetically. Hence, theresearch requires a blended effort in three distinct areas: (i)electromagnetics and near-field exposure modeling with multipletransmitters, (ii) wireless communication system far-fieldinformation-theoretic performance evaluation with a near-field SARconstraint, (iii) the design of SAR codes for optimum performance. Codeperformance will be determined by simulation and by laboratory evaluationwith microwave equipment for near-field SAR and far-field error-ratemeasurements.