Comparative Study for Channel Pairing in NOMA OFDM- CDMA System

Orthogonal Multiple Access such as OFDM technique became inadequate scheme since it provides limited spectral efficiency and limited number of users. In addition to Orthogonal Multiple Access (OMA), Non-Orthogonal Multiple Access (NOMA) technique is applied in 5th generation of mobile communications that enhances both spectral efficiency and capacity with high Quality of Service (QoS). In this paper, three techniques were combined NOMA, OFDM, and CDMA in order to have optimal system performance in the presence of worst fading channel situations; fast frequency selective Rayleigh multi-path fading channel. The main contribution of this paper is the novel channel pairing technique introduced to PD-NOMA (Power Domain- NOMA) techniques denoted by Optimal Channel Pairing technique. This proposed pairing technique will be compared at the end of this paper, using MTALB Code simulation with two old paring techniques in PD-NOMA system, which are random pairing and orthogonal pairing.