A DFRC (
radar-communication integration)
system solves the problem of spectrum congestion caused by increase of
wireless application requirements, but in an actual environment, a
wireless transmission environment is very complex, functions of
radar and communication can be affected, and the DFRC
system can be applied to a
wireless communication
system, so that the DFRC system can be applied to a wireless communication system, and the DFRC system can be applied to the wireless communication system. The invention researches a joint design method for forming a DFRC transmitted waveform and an RIS reflected wave beam by taking a Cramer-Rao bound for minimizing
radar parameter
estimation as a criterion and taking a
signal to interference plus
noise ratio demand of a communication user under a symbol-level
precoding system as a constraint. According to the invention, the proposed joint design problem is described as a non-convex
optimization problem with the non-convex objective function and the constant modulus constraint. According to the method, multiple variables are decoupled under an alternating optimization framework, and a transmitted waveform optimization sub-problem and an RIS
reflection coefficient optimization sub-problem are solved respectively. According to the method, an auxiliary variable is introduced, a non-convex problem is converted into a convex problem on the basis of Scherr relaxation, and then effective solving is conducted through an existing convex optimization method; according to the method, a fractional part in a target function is processed through an auxiliary variable and Scherr complementary
processing, the fractional part is converted into a differential convex function form, and then iterative solution is carried out through a successive convex
approximation algorithm in combination with a penalty method.The numerical experiment result shows that the
radar detection parameter
estimation performance is improved while the communication performance is guaranteed through the
algorithm.