Abstract: In order to apply the non-orthogonal multiple access (NOMA) technology more extensively, this paper proposes an uplink NOMA system based on dynamic users. In the traditional NOMA system, the accurate distance between the user and the BS was fed back to the user. However, if the BS feeds back the specific distance in real time in the system with dynamic users, the overhead will be excessive. Therefore, it is assumed that the BS only feeds back the statistical characteristics of the distance which is used by the user to determine the transmit power in the subsequent information transmission. The outage performance of the proposed system is theoretically analyzed and the expression of the outage probability is derived. Simulations verify the accuracy of the theoretical results and show that using statistical characteristics or using specific distance to determine the transmit power can obtain almost the same outage performance if the boundary values of a user's area are not much different.