EAGER: Multiple Transmitter Chains to Minimize Exposure to Electromagnetic Radiation in Portable Devices

手机等便携式无线设备正在成为计算能力的强大设备，它们拥有多个处理器、大容量内存、触摸屏、摄像头和运动传感器，所有这些都与WiFi、蓝牙、3G和4G收发器相连。许多收发器可以同时传输，每次传输都会使用户暴露在一定程度的电磁辐射下。总的暴露可能是累积的。与此同时，随着新科学的出现以及公众对便携式无线设备的依赖程度越来越高，联邦通信委员会（FCC）等监管机构不断面临重新评估电磁辐射暴露阈值的挑战。本研究探讨了使用多个发射器，通常用于提高无线性能，作为减少暴露的工具。本研究：(i)评估便携式设备的暴露效应作为其发射器特性和发射器元件之间的时序和相位的函数；（ii）设计通信和约束编码技术，在不牺牲无线性能的同时最大限度地减少暴露；（iii）使用公认的暴露测试程序，如1.6 W/kg的SAR（比吸收率）限值，评估这些技术的成功程度。该研究在决定暴露的近场能量最小化和决定无线通信系统性能的远场能量最大化之间进行了权衡。

Portable wireless devices such as cell phones are becoming powerhouses of computational ability, with multiple processors, large amounts of memory, touch screens, cameras, and motion sensors all connected to WiFi, Bluetooth, 3G and 4G transceivers. Many of these transceivers can transmit concurrently, and each transmission exposes the user to some level of electromagnetic radiation. The total exposure is potentially cumulative. At the same time, regulatory agencies such as the Federal Communication Commission (FCC) are constantly being challenged to re-evaluate their thresholds for exposure to electromagnetic radiation as new science becomes available and as the public becomes more reliant on portable wireless devices. This research examines using multiple transmitters, commonly used to improve wireless performance, as a tool to minimize exposure. This research: (i) evaluates the exposure effects of a portable device as a function of its transmitter characteristics and the timing and phasing between transmitter elements; (ii) designs communication and constrained coding techniques that minimize exposure while not sacrificing wireless performance; (iii) evaluates the success of these techniques using accepted testing procedures for exposure such as the SAR (specific absorption rate) limit of 1.6 W/kg. The research characterizes the tradeoff between minimizing near-field energy, which determines exposure, and maximizing far-field energy, which determines wireless communication system performance.