Performance Analysis of Code-Domain NOMA in 5G Communication Systems

Today’s wireless communication networks transmit their signals based on the Orthogonal Multiple Access (OMA) principle. As the number of users increases, OMA based approaches may fail to meet the stringent requirements emerging in the 5th Generation of wireless communications for very high spectral efficiency and massive connectivity. Non-Orthogonal Multiple Access (NOMA) emerges as a solution to improve upon spectral efficiency and user capacity without sacrificing system performance. This paper aims to demonstrate the validity of NOMA as an optimal choice for 5G by comparing it with OMA. Three Code-Domain NOMA (CD-NOMA) schemes are examined and compared with an established OMA technique, Orthogonal Frequency Division Multiplexing (OFDM). The chosen schemes for CD-NOMA are: Low Density Spreading CDMA (LDS-CDMA), Low Density Spreading OFDM (LDS-OFDM), and Sparse Coding Multiple Access (SCMA). The performance of each scheme is evaluated by computing
its Bit error rate (BER) and Outage Probability (OP) and simulating them against different values of Signal-to-Noise-Ratio (SNR) over an AWGN channel. It is observed in this paper that, while having varying performance levels, every NOMA scheme outperforms OFDM, thereby proving NOMA to be a prime candidate for implementation in future 5G communication technologies.