Performance of Alamouti STBC NOMA Signals in Rayleigh Fading Channels

In this study, a 3-user NOMA structure consisting of a single receiver and a single transmitter was used, using the Nonorthogonal Multiple Access (NOMA) technique developed for 5G, the new generation communication technology, and a 2x1 (2 Transmitting Antenna - 1 Receiving Antenna) structure with 3 users at different distances. ) The performances of the Alamouti Space-Time Block Coding (STBC) NOMA structure and the 2x2 (2 Transmitting Antennas-2 Receiving Antennas) Alamouti Space-Time Block Coding (STBC) NOMA structure with three users at different distances are compared in the Rayleigh Channel. Simulations were carried out in the MATLAB program depending on the Power variable (P). Quadrature Phase Shift Keying (QPSK) modulation method was used in the simulations. Performance analyzes were examined by comparing the graphs of changes in Bit Error Rate (BER) in the simulations performed. As a result of examining the graphics, it was concluded that 2x2 Alamouti STBC NOMA has better BER performance for each user (Near User, Middle User, Remote User) in Rayleigh Channel compared to 2x1 Alamouti STBC NOMA and the NOMA structure consisting of a single receiver and transmitter.