  We consider uplink power control in wireless communication when massive users
compete over the channel resources. In Part I, we have formulated massive
transmission power control contest in a mean-field game framework. In this
part, our goal is to investigate whether the power-domain non-orthogonal
multiple access (NOMA) protocol can regulate the non-cooperative channel access
behaviors, i.e., steering the competition among the non-cooperative users in a
direction with improved efficiency and fairness. It is compared with the CDMA
protocol, which drives each user to fiercely compete against the population,
hence the efficiency of channel usage is sacrificed. The existence and
uniqueness of an equilibrium strategy under CDMA and NOMA have already been
characterized in Part I. In this paper, we adopt the social welfare of the
population as the performance metric, which is defined as the expectation of
utility over the distribution of different types of channel users. It is shown
that under the corresponding equilibrium strategies, NOMA outperforms CDMA in
the social welfare achieved, which is illustrated through simulation with
different unit price for power consumption. Moreover, it can be observed from
numerical results that NOMA can improve the fairness of the achieved data rates
among different users.
