Symbiotic NOMA: A Mutualism Communication Paradigm Toward Green Massive Access

In this letter, we propose a symbiotic non-orthogonal multiple access (NOMA) mutually reinforcing paradigm for green massive access to better meet the diverse and challenging requirements of Internet-of-Things. In particular, the backscatter device (BD) utilizes the same spectrum resources of the legacy users for reflection while providing beneficial multipath to enhance the performance of legacy transmission. We aim to jointly optimize the active/receive beamforming vectors and reflection coefficients to maximize the weighted sum rate, proving that there is no need to design a dedicated beam for BD via the developed analytical results. Simulation results validate the superiority of the symbiotic NOMA scheme.