Non Orthogonal Multiple Access with Energy Harvesting Using Reconfigurable Intelligent Surfaces for Rayleigh Channels

In this paper, we derive the throughput of non orthogonal multiple access (NOMA) through reconfigurable intelligent surfaces (RIS) with energy harvesting. The transmitter harvests energy using the radio frequency (RF) signal received from another node N. Node N can be any node transmitting RF signals. The harvested energy is used to transmit data to N NOMA users using RIS. RIS is placed between the transmitter and users. Different sets of reflectors are dedicated to different users. Each user receives all reflections over RIS with the same phase. We also optimize harvesting duration and power allocation coefficients to maximize the total throughput. We suggest the use of two RIS: the first RIS improves the energy harvesting process and is placed between node N and transmitter T. The second RIS is placed between T and users so that reflections have a null phase at all NOMA users. The derived results are valid for Rayleigh fading channels where the transmitter harvests energy using the received RF signals. We derive the throughput at weak and strong users as well as the total throughput of NOMA systems using RIS with energy harvesting. In this paper, we derive the packet error probability and total throughput for NOMA using RIS with energy harvesting using RF signals. When there are two users and 16QAM modulation is used and for a throughput of 3.5 bit/s/Hz, the use of R= 512 , 256 , 128 , 64 , 32 , 16 , 8 reflectors offers 69 dB, 62.8 dB, 57 dB, 50.9 dB, 45 dB, 38.5 dB, 31.8 dB gain with respect to the absence of RIS (Mondal et al. in Wirel Pers Commun, 2021; Le and Kong in Wirel Pers Commun 116:3577–3597, 2021).