A conference system is provided for connection in a digital audio signal transmission system, for receiving N encoded audio signals from N conferees, wherein N is a positive integer greater than or equal to three. Since the feedback mechanism based on the codebook is employed in the collaborative MIMO system in the present invention to enable the BS to obtain the precoding information, the present invention can be used to the both TDD mode and FDD mode. The invention further provides an electronic device to implement the method.