The demand for wireless communication services is increasing in last few years at very fast rate. Safeguarding, distribution and communicating data is of prime concern in future wireless communication systems. So, high rate of data is one of the essential qualities for upcoming wireless systems. However, while transmitting the signal to receiver, there is arbitrarily delayed, scattered and diffracted signal due to fading in the signal. This deterioration in signal quality leads to serious degradation within link signal to noise (SNR). In this paper, we obtain expression for probability density function (PDF) of outage probability. We also obtained the novel expression for the capacity analysis of Full duplex (FD) non-orthogonal multiple access (NOMA) under adaptive policies namely constant power with optimal rate adaptation (ORA). Finally, computer simulations are done for the verification of accuracy of the analytical results.