Research On Information Freshness Of Energy Constrained Wireless Sensor Networks For B5G/6G

In pursuit of the noble vision of “One thought creates the universe,all things follow the heart”,the development of B5G/6G technology is being comprehensively promoted.These cutting-edge technologies have enabled the explosive emergence of internet of things(Io T)devices,resulting in the skyrocketing cost of network energy consumption.For wireless nodes or devices that are not suitable for battery deployment or frequent battery replacement,insufficient power will result in the monitoring terminal receiving outdated status updates,and endangers the reliability and stability of the entire Io T system.On the one hand,energy harvesting(EH)not only prolongs the lifespan of energy-limited Io T devices,it is also consistent with the ”carbon peaking and carbon neutrality”.On the other hand,from the perspective of monitoring terminals,the age of information(Ao I)accurately quantifies the freshness of status updates.Therefore,thesis explores the application of Ao I in energy-limited wireless sensor networks.The main research topics are as follows:(1)The thesis proposes a novel Io T model that utilizes both radio frequency(RF)and non-RF EH to overcome the unpredictability of natural energy sources.The network consists of three interdependent subnetworks: sensor state updating,cellular backhaul,and energy harvesting and transmission.The energy harvesting and transmission network collects energy from natural resources and transmits it to the sensors.For the proposed network,firstly,a Markov chain with discrete energy states for the energy station is constructed,along with the corresponding transition matrix,to obtain the steady-state probability of energy transfer at the energy station and the statistical description of complete sensor charging.Secondly,the mathematical formulas for average and peak Ao I are derived by analyzing the cellular backhaul and energy harvesting and transmission subnetworks separately.Finally,the impact of system parameters on Ao I is analyzed from the perspectives of the energy harvesting and transmission subnetwork,the cellular backhaul subnetwork,and the sensor state updating subnetwork.Simulation show that the proposed sensor network outperforms traditional sensor networks that rely solely on natural energy sources.(2)The thesis proposes a wireless sensor network that utilizes relay assistance for energy supply,to overcome energy and coverage limitations of sensors,while maintaining the freshness of status updates through short packet communication.For the proposed network,firstly,the end-to-end packet transmission error probability is obtained by analyzing the end-to-end approximate signal-to-noise ratio.Secondly,by jointly considering the outdated channel state information and EH,a statistical description of the sensor full charging time and the state update transmission interval is obtained,and a mathematical expression for the average Ao I of the network is derived.Finally,a trade-off model between Ao I and energy efficiency is established.Simulation results verify that the conventional automatic retransmission request scheme outperforms the truncated automatic retransmission request scheme in the considered model.