Research On Optimal Resources Allocation Of Backscatter Communication System In Complex Environment

With the development of the Internet of things technology,large-scale equipment will consume spectrum resources and energy,cognitive radio powered by ambient radio frequency signals is an effective solution.In this network,the secondary transmitter harvests energy from ambient signals to transmit data to the secondary receiver without causing harmful interference to the primary user.This protocol is called ”Harvest Then Transmit”(HTT),but the performance of the network depends on the energy that can be harvested and the activity of the primary channel.To solve this problem,the ambient backscatter communication technology is introduced,which can reflect the primary signal and modulate its own information.The secondary receiver uses the corresponding mechanism to demodulate,ensuring the communication performance of the secondary network when the primary channel is active.However,the HTT mode and the backscatter mode cannot be carried out simultaneously.In order to find the optimal transmission strategy for the secondary transmitter,it’s necessary to balance the time of HTT mode or backscatter mode to achieve the optimal system performance.In addition,in practical scenarios,it is necessary to consider the impact of external interference,busy period of authorized channels,and ambient radio freqency signals on the performance of secondary system This thesis studies the models of maximizing transmission rate and energy efficiency of secondary systems under complex environment,and conducts theoretical analysis and simulation verification.The main contents are as follows:1.Introduce the spectrum sharing mode of cognitive radio,the ambient backscatter communication and the non-linear energy harvesting model,which will lay a theoretical basis for the subsequent construction of optimal resource allocation models under different scenarios.2.When there is interference in the secondary system with fixed backscatter rate under overlay mode,a model aiming at maximizing its transmission rate is proposed to study the time allocation scheme and distribution characteristics,and simulate the maximum transmission rate of the system under different interference power.3.The problem of maximizing the transmission rate of secondary systems with the introduction of ambient backscatter communication and non-linear energy harvesting models are presented,and the corresponding resource allocation schemes are obtained in the overlay and underlay scenarios,respectively.4.Establish the optimal energy efficiency model for the secondary system with both backscatter and HTT modes in overlay and underlay scenarios,and the algorithms based on Dinkelbach’s method are proposed,respectively.The simulation verifies that the algorithms can converge quickly.