Research On Intelligent Reflecting Surface Aided Communication Optimization Problem

With the rapid development of wireless communication,people's expectations for the wireless communication technology are rising continuously.The fifth generation of mobile communication,which is still being widely deployed at present,has met people's requirements for the communication with high rate and low delay to a great extent.However,this generation of mobile communication has some shortcomings such as the high hardware cost,high power consumption and high complexity,which not only brings about many inconveniences to the deployment,operation and maintenance of the operators,but also enormously makes the users' cost performance experience worse.In view of this,in the process of studying the next generation of mobile communication,the academia puts forward the concept of Intelligent Reflecting Surface(IRS)and applies it to the wireless communication system to solve these problems.IRS is a kind of plane integrated with a large number of low-cost,low-loss and reconfigurable passive reflecting antenna elements,which can intelligently configure signal propagation and improve the spectrum efficiency and energy efficiency of wireless networks.Specifically,after the user's position is known,the reflection phase of the signal is calculated by using an optimization algorithm to improve the power received by the user.In this paper,we innovatively propose a wireless communication system with dual IRS in a small indoor environment.When the direct link between the base station and the user is unavailable,the system uses two IRS in cooperation to enhance the signal power received by the user.The phase shift matrix of the two IRS are regarded as the variables to optimize,and the signal power received by the user is maximized.The system is modeled as a non-convex network optimization problem that is simulated by an Interior Point Optimization(IPOPT)solver,and the performance of the system is compared with that of the model without cooperation.The comparison results show that the model with cooperation has better enhancement effect than the model without cooperation in the indoor small-scale environment.