Non-orthogonal multiple access relaying for device-to-device communication

Recently, non-orthogonal multiple access (NOMA) has gained a great deal of attention due to its ability to simultaneously transmit multiple streams. Device-to-device (D2D) relaying can increase the spectral efficiency via direct communication between two devices, and extends coverage by relaying signals from the base station. In this letter, we propose applying the NOMA technique for D2D relay where D2D relaying and D2D communication can be done simultaneously in the power domain. The proposed scheme can achieve higher spectral efficiency, and its performance is evaluated through extensive simulations in multiple-cell environments, compared with conventional D2D relay schemes.