This chapter considers coexistence between the nonorthogonal multiplexing access (NOMA) device‐to‐device (D2D) downlink system and the uplink cellular system extending the centralized models developed in literature. D2D communications can potentially facilitate peer‐to‐peer services. Considering the potentials of D2D and NOMA, it is essential to explore whether NOMA can be combined with D2D communication systems to maximize efficiency. The chapter proposes an effective subchannel allocation and user pairing method to mitigate the interference from cellular users to D2D users. It outlines the total transmit power consumption of the D2D users subject to the subchannel assignment and power control constraints. The chapter proposes a pairing method that aims at minimizing the total transmit power of the D2D transmitter devices. Numerical results demonstrate the important roles of pairing methods and subchannel assignment in reducing the total transmit power of the network that serves both D2D devices and cellular users.