A multi-user access scheme for throughput enhancement in UDN with NOMA

Abstract

Ultra Dense network (UDN) is considered as one of the promising and efficient communication solution for high throughput and large connection numbers scenarios. Due to the densification of the users perspective and massive-access opportunities, how to optimize the multiple users access in UDN is an important and complicated problem. The traditional multi-user access schemes may be no longer suitable. Thus, in this paper, we investigate the multi-user access issue with densely-deployed access points (APs) in UDN. Moreover, to further enhance the system throughput and meet the high rate demands of users, the non-orthogonal multiple access (NOMA) is introduced into UDN. Considering the network densification and newly incorporated technological features, we formulate the multi-user access and corresponding resource allocation problem as an optimization problem to enhance the system throughput. To solve it with low-computation complexity, this complex problem is divided into two sub phases, APs association and resource allocation. First, we propose a matching algorithm to assign proper APs and resource blocks (RBs) to the multiple users. According to the channel state information and data rate requirement, a stable matching among the sets of APs, users and RBs is formed after a limited number of iterations. Then, we allocate the transmit power for associated APs based on NOMA by utilizing the differ convex (DC) programming. Numerical results show that the proposed scheme achieves a better performance compared with exiting schemes.