In this paper, cooperative non-orthogonal multiple access (NOMA) helps device-to-device (D2D) communication in the downlink. In particular, we investigate relay selection scheme as best channel condition for dedicated users where a different data transmission demand on each user. In particular, the outage probability of both users is investigated, and several impacts on system performance are presented. By simulation implementation, the proposed D2D-NOMA system introduces expected performance on reasonable selected parameters in the moderate signal to noise ratio regime.

D2D, NOMA, relay selection.