Research On Massive MIMO Precoding In Heterogeneous Networks

This paper mainly studies the improvement of the Massive MIMO(Multiple Input and Multiple Output) precoding methods in the heterogeneous networks. This paper proposes a hybrid precoding method for the Massive MIMO system, which combines the traditional linear precoding schemes. It also designs an SDN (Software Defined Network)aided heterogeneous network architecture and an interference-free hybrid precoding scheme for the heterogeneous network architecture.This paper introduces and summarizes the present research status of the Massive MIMO precoding technologies. In particular, among these precoding methods, this paper gives a detail expression of the hybrid precoding method which has a better application prospect. Therefore, this paper proposes a hybrid precoding scheme, which combines the traditionallinear precoding methods with the hybrid precoding concept. The proposedscheme can overcome the physical constraint in Massive MIMO system while maintaining considerable system performance and keep the corresponding linear precoding method's characteristics.This paper further studies the application of the proposed hybrid precoding method in the heterogeneous networks. To deal with enormous radio resource management problem in the network, this paper proposes an SDN aided heterogeneous network architecture to centrally manage and coordinate the network resource and user information. Based on the proposed network architecture, this paper further improves the Massive MIMO precoding scheme to reduce interference. By using the null-space method, the proposed precoding scheme maps the precoding matrix to the null-space of the victim user channel. In this way, the interference from low power nodes to the victim users will be eliminated and the inter-tier interference in the heterogeneous networks will be significantly alleviated.The proposed scheme can increase the user's quality of service and improve the system performance.