A study of transfer function estimation error and a practical multibeam antenna system with precoding interference cancellation

Beyond IMT-2000, systems must use high ability interference canceling technology to achieve high speed and high capacity transmission. This paper proposes a kind of precoding technology that, in a practical manner, can completely cancel downlink interference in the same space and the same frequency band. The concept of this technology is to multiply the transmitting signal by the inverse matrix of the space transfer functions matrix sent by each mobile station. Its high interference cancellation performance is evaluated by considering the error in estimating the transfer function. A new scheme is proposed that is extremely practical because it eliminates the need to measure the delay. A fully implemented system is described.