A Low-Complexity Coding Scheme for NOMA

• Published in: IEEE systems journal Vol. 17; no. 3; pp. 4464 - 4473
• Main Authors: Abd-Alaziz, Wael, Jebur, Bilal A., Fakhrey, Harih, Mei, Zhen, Rabie, Khaled
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Binary phase shift keying; Bit error rate; Coding; Complexity; Complexity theory; Constructive interference; convolutional codes; Decoding; Encoding; Floating point arithmetic; Interference; low-complexity coding; Monte Carlo simulation; NOMA; Nonorthogonal multiple access; nonorthogonal multiple access (NOMA); Resource management; Waveforms; Working conditions
• ISSN: 1932-8184; 1937-9234
• DOI: 10.1109/JSYST.2023.3262174

This work focuses on exploiting the constructive interference among different users' data waveforms to introduce new coding and decoding techniques, which are specifically designed for nonorthogonal multiple access (NOMA) systems. In this article, a structured coding scheme is devised. In essence, the proposed technique focuses on finding a relationship between the sent users' data waveforms and then uses this relationship in the decoding process at the receiving destination. It is worth pointing out that the proposed coding and decoding techniques exhibit better performance and reduced the complexity compared with the conventional uncoded NOMA. The complexity order evaluation shows that the proposed scheme attains a reduction in the required number of the floating point operations of <inline-formula><tex-math notation="LaTeX">\text{5}</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">\text{6}\,N</tex-math></inline-formula> at the second and third users, respectively, compared with that of the uncoded NOMA. Moreover, we have derived a closed-form expression for the bit error rate, which is verified using the Monte Carlo simulation. To demonstrate the practicality of the proposed system, the obtained results are compared with those of the uncoded and convolutional coding NOMA systems. Finally, the performance of the proposed system outperformed the conventional systems by an average of 5 dB in the case of two users and an average of 15 dB in the case of three users in the same work environment.