Receiver's Multi-Antenna Coupling Cancellation Based on Guided Multi-level Search

In order to achieve higher bit rates and gain diversity, recent trends in communication industry include the use of multiple antennas in transmitter and at the receiver. At the same time the terminals are getting smaller incrementing the level of electronic interferences in their interior. In this contribution, the signal distortion known as RF front-end antenna coupling is analyzed. The coupling between antennas is modeled with polynomials limited to third order nonlinear behavior. Nonlinear software decoupling module, located at the output of analog-to-digital (AD) converter, is proposed for coupling cancellation. Inside the module, signal enhancement is achieved with the approximation of inverse nonlinear coupling function with the polynomial of 9th degree. The inverse function is obtained using guided multilevel search approximation method. The proposed coupling cancellation algorithm is analyzed under different system conditions showing excellent coupling cancellation characteristics.