Research On Aperture-level Simultaneous Transmit And Receive Of Digital Array

At present,radio frequency can not work in the same band simultaneously because of strong self-interference.And simultaneous transmit and receive(STAR)is a rising technology to overcome this limitation by providing high transmit-receive isolation.Traditional STAR is mainly used in one or two pairs of antenna elements,but this paper focuses on large digital arrays,and providing some methods for achieving aperture level STAR technology.We mainly use method in spatial domain method.Firstly,we use linear digital beamforming(DBF)to mitigate self-interference.And we construct linear equations by minimizing coupling signal and maximizing gain in direction of interest,the solution of the equations used as weighting vector.This method has low computational complexity,but it is only suitable for linear power amplifier.Secondly,we use adaptive DBF and Lagrangian multiplier method.We take output power as objective function,and use constraints mentioned above to construct Lagrangian equation,and the weighting vector can be obtained in LCMV rule.The adaptive DBF can acquire optimal vector in different environment,but it needs prior information of input signal.Thirdly,we use phase-only DBF to achieve high isolation.The basic phase-only DBF uses phase-only constraint to construct equations.And another phase-only algorithm with the maximization of expected-direction gain can be operated by constructing Lagrangian function.Phase-only DBF is suitable for engineering application because it is suitable for saturation power amplifier.Finally,this paper uses adaptive digital cancellation to minimize the residual of the interference.We take the residual as reference signal,respectively obtaining the Wiener solution,solution from steepest descent method and solution from stochastic gradient descent method.The result shows that digital cancellation can effectively minimize residual of interference signal.