基于混合储能和能量捕获的多接入信道容量建模与分析

Modeling and analysis of multiple access channel capacity based on hybrid energy storage and energy harvesting

能量捕获具有部署灵活和可持续供能的优点,已成为解决物联网中设备能量受限的有效途径之一。针对基于能量捕获的多接入信道,能量捕获技术存在能量来源不稳定、存储设备容量有限等因素,因此采用基于超级电容和电池的混合储能结构。根据其信道的特点和能量捕获的随机特性,引入节点能量约束关系,提出了一种呈指数型下降(ETD)的近似最优能量分配策略对平均吞吐量进行分析,推导其上下界及其常数差值。最后利用平均吞吐量和信道容量的关系求得近似信道容量。实验分析了捕获能量、储能容量以及节点数目对多接入信道容量的影响,同时实验结果表明,相比传统节点采用电池作为单一储能单元,采用混合储能结构可以有效地提高节点的捕获能量数值,使其在信号的发送上采用多进制的传输方式,进而增大多接入信道的容量。

Energy harvesting(EH)has been considered as a promising technology to solve the constrained energy problem in the devices of IoT with its advantages of flexible deployment and sustainable energy supply.For multiple access channel with energy harvesting,a hybrid energy storage structure model composed by super capacitor and battery was proposed for the devices of IoT.According to the peculiarities of medium access channel and energy harvesting system,an optimized energy allocation strategy with exponential-type decline(ETD)was presented,the upper and lower bounds of the average throughput were deduced,in particular,the gap of two bounds was derived to be a constant.The channel capacity was further obtained by utilizing the relationship between the average throughput and the channel capacity.In the simulations,the effect of harvested energy,storage capacity and the number of nodes on the channel capacity were analyzed respectively.Experiment results show that compared with the conventional wireless node with single battery storage,the proposed hybrid energy storage structure can improve the harvested energy value and increase the multiple access channel capacity by using adaptive modulation scheme when transmitting the signals.