Abstract— Recently, non-orthogonal multiple access (NOMA) has been developed as an alternative to orthogonal multiple access (OMA) to fulfill the need of connecting massive number of devices with high requirements of 5G wireless communication. In this work, two types of transmitter antenna selection (TAS) are employed – in down link NOMA amplify and forward cooperative relay system over Rayleigh fading channels – to enhance the bit error rate (BER) performance. The first TAS, which is based on maximum ratio combining at relay is applied on the first hop, and the second TAS with maximum likelihood and successive interference cancellation detection based on minimizing average BER at mobile end user is applied on second hop. The obtained results reveal that the proposed TAS schemes enhance the performance of NOMA cooperative relay system significantly compared to other TAS that were used as a reference in this work, namely antenna random selection scheme and equal gain combining of all antennas.