Massive connectivity, high mobility, high data rates, ultra-reliable, and low latency applications are all requirements for future wireless networks (5G and beyond). The ultimate barrier to achieving high capacity and low latency is the channel. All the previous generations of cellular technology only adapt to the channel but have no control over it, due to which there is significant performance loss. Recent studies reveal that the Intelligent Reflecting Surface (IRS) is the best possible solution to have good control over the channel by intentionally modifying the phases of the incident signal, thereby mitigating channel ill-effects and thus improving the reliability of the system. As a result, IRS is proposed as a viable candidate for future wireless environments. By enabling several users to use the same radio resources, Non-Orthogonal Multiple Access (NOMA) gains high spectral efficiency and offers massive connectivity. The main objective of the proposed work is to analyze the Bit Error Rate (BER) performance of IRS and Relay-Assisted NOMA systems with Interference Cancellation at the relay node. The obtained simulation results indicate that the BER performance of the overall system is improved and Far User (FU) performance is significantly improved by the interference cancellation at the relay node.