  In this paper, a non-orthogonal multiple access (NOMA) system with partial
channel state information (CSI) for downlink and uplink transmission in mobile
scenarios is considered, i.e., users are deployed randomly and will move
casually around the base station (BS). In this case, the channel gain of each
user varies over time, which has an influence on the performance of
conventional NOMA. An analytical framework is developed to evaluate the impact
of position estimation deviation in terms of decoding order error probability,
average sum rate and outage probability. Based on the framework, dynamic power
allocation (DPA) for downlink NOMA and dynamic power control (DPC) for uplink
NOMA are put forward to optimize the outage performance with user distance
information. It has been shown that the performance of NOMA relies on accurate
user position information. To this end, two algorithms based on position
filtering are proposed to improve the accuracy of user position. Monte Carlo
simulation is presented to demonstrate the improvement of spectrum efficiency
and outage performance. Simulation results verify the accuracy of the proposed
analytical framework.
