Backscatter-NOMA - An Integrated System of Cellular and Internet-of-Things Networks.

Non-orthogonal multiple access (NOMA) is envisioned to be a key technology to enhance the spectrum efficiency for SG cellular networks. Meanwhile, ambient backscatter communication (AmBC) is considered as a promising solution to Internet-of-Things (IoT), due to its high spectrum- and power-efficiency. In this paper, we are interested in an integrated system of cellular and IoT networks, and propose a backscatter-NOMA system, which incorporates a downlink NOMA system with backscatter devices. In this system, the base station (BS) transmits information to two cellular users according to the NOMA protocol, while a backscatter device transmits its information over the BS signals to one cellular user using passive radio technology. We derive the closed-form expressions of the outage probabilities and analyze the diversity orders of all relevant transmissions in the proposed system. Finally, we provide numerical results to verify the theoretical analysis.