In this paper, we study terahertz (THz) simultaneous wireless information and power transfer (SWIPT) for future micro-scale 6G Internet-of-Things (IoT) networks. Since Schottky diodes are not efficient for THz energy harvesting (EH), we propose resonant tunneling diodes (RTDs) for EH at the IoT receiver (RX). As the electrical properties of RTDs are different from those of Schottky diodes, we develop a novel closed-form EH model for RTD-based RXs. In particular, we model the dependency of the instantaneous RX output power on the instantaneous received power by a non-linear piecewise function, whose parameters are adjusted to fit circuit simulation results. Furthermore, since coherent information detection is challenging at THz frequencies, we employ unipolar amplitude shift keying (ASK) modulation at the transmitter (TX) and utilize the RTD-based EH circuit at the RX to extract both information and energy from the received signal. We formulate an optimization problem to maximize the mutual information between the TX and RX signals subject to constraints on the peak amplitude of the transmitted signal and the required average harvested power at the RX. Moreover, we determine a feasibility condition for the formulated problem and, for high and low required average harvested powers, we derive the achievable information rate numerically and in closed form, respectively. Our simulation results highlight a tradeoff between the information rate and the average harvested power. Finally, we show that this tradeoff is determined by the peak amplitude of the transmitted signal and the maximum instantaneous harvested power for low and high received signal powers, respectively.

翻译：本文研究了适用于未来微型6G物联网（IoT）网络的太赫兹（THz）同步无线信息和功率传输（SWIPT）技术。由于肖特基二极管在太赫兹能量收集（EH）中效率较低，我们提出在物联网接收端（RX）采用谐振隧穿二极管（RTD）进行能量收集。鉴于RTD与肖特基二极管的电学特性存在差异，我们为基于RTD的接收端开发了一种新型闭式能量收集模型。具体而言，我们通过非线性分段函数建立瞬时接收功率与瞬时输出功率之间的依赖关系，并通过调整函数参数拟合电路仿真结果。此外，针对太赫兹频段相干信息检测的困难，我们在发射端（TX）采用单极性幅度键控（ASK）调制，并利用接收端的基于RTD的能量收集电路从接收信号中同时提取信息与能量。我们建立了一个优化问题，在满足发射信号峰值幅度约束和接收端所需平均收集功率的前提下，最大化发射端与接收端信号之间的互信息。同时，我们确定了该问题的可行性条件，并针对高/低所需平均收集功率场景，分别通过数值计算和闭式推导得出可达信息速率。仿真结果显示信息速率与平均收集功率之间存在权衡关系。最终表明，在低接收信号功率条件下该权衡由发射信号峰值幅度决定，而在高接收信号功率条件下则由最大瞬时收集功率决定。