Reconfigurable smart surface assisted joint optimization method for spectrum efficiency and energy efficiency of multi-user MISO downlink wireless communication

Abstract

The invention discloses a reconfigurable intelligent surface-assisted multi-user MISO downlink wireless communication energy efficiency and spectrum efficiency joint optimization method, which comprises the following steps: in the multi-user MISO downlink transmission, a base station sends a signal to the reconfigurable intelligent surface, which can Reconstruct the path to the user after reflection from the smart surface, as well as the path directly from the base station to the user; based on the joint optimization of energy efficiency and spectrum efficiency as a criterion, the precoding matrix of the base station and the reflection coefficient matrix of the reconfigurable smart surface are jointly optimized; the energy efficiency The goal of joint spectral efficiency optimization is to maximize the weighted sum of system energy efficiency and spectral efficiency under the constraints of base station transmission power; the present invention realizes base station side precoding matrix and RIS through alternate optimization, Quadratic transformation, WMMSE transformation and convex optimization algorithm Joint optimization of reflection coefficient matrices. The invention has low algorithm complexity, can effectively improve the energy efficiency and spectrum efficiency of multi-user MISO downlink communication, and realize the balance between the two.

Description

technical field [0001] The invention belongs to the communication field, and in particular relates to a method for joint optimization of spectrum efficiency and energy efficiency of multi-user MISO downlink wireless communication aided by a reconfigurable intelligent surface. Background technique [0002] A reconfigurable intelligent surface (Reconfigurable Intelligent Surface, RIS) is an artificial radio structure with low cost components. RIS can be programmed to redirect incoming radio frequency waves in specific directions, making it possible to control radio wave propagation in wireless communications at relatively low cost. Since the environment is usually considered as an uncontrollable factor in wireless communication, RIS, which can be continuously reprogrammed, can adapt to the time-varying wireless communication environment more easily than traditional devices to have better performance. [0003] In the research of RIS-assisted wireless communication, both spectr...

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Problems solved by technology

For the optimization problem of maximizing the weighted sum of energy efficiency and spectral efficiency, since the objective function is non-convex, and the constraint of RIS reflection coefficient is also non-convex, it is usually difficult to solve

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