The authors propose a technique that is capable of doubling the spectral efficiency per area and per device by modulating a recently developed multiple access design called multi-user auxiliary signal superposition transmission through a transmission technique called OFDM-SPM
The world of today is characterized by a very huge inter-connectivity of data-hungry devices. This imposes on wireless system designers not only developing techniques that are spectrally efficient at the area level where many users are served with the same resources simultaneously but also developing techniques that are spectrally efficient at the device level as well. For addressing this problem, we propose in this paper a technique that is capable of doubling the spectral efficiency per area and per device by modulating a recently developed multiple access design called multi-user auxiliary signal superposition transmission (MU-AS-ST) through a multi-dimensional OFDM technique termed OFDM with subcarrier power modulation (OFDM-SPM). This integration results in the technique proposed in this paper and yields, with doubling the spectral efficiency, merits such as robust security, low complexity, and enhanced transmission reliability.
Keywords: OFDM, OFDM-SNM, subcarrier number modulation, wireless communication, 5G, 6G, multi-user, future wireless networks.
 I. F. Akyildiz, A. Kak and S. Nie, "6G and Beyond: The Future of Wireless Communications Systems," in IEEE Access, vol. 8, pp. 133995-134030, 2020, doi: 10.1109/ACCESS.2020.3010896.
 S. M. R. Islam, N. Avazov, O. A. Dobre and K. Kwak, "Power-Domain Non-Orthogonal Multiple Access (NOMA) in 5G Systems: Potentials and Challenges," in IEEE Communications Surveys & Tutorials, vol. 19, no. 2, pp. 721-742, Second quarter 2017, doi: 10.1109/COMST.2016.2621116.
 J. Zeng et al., "Investigation on Evolving Single-Carrier NOMA Into Multi-Carrier NOMA in 5G," in IEEE Access, vol. 6, pp. 48268-48288, 2018, doi: 10.1109/ACCESS.2018.2868093.
 M. M. ¸Sahin and H. Arslan, "Waveform-Domain NOMA: The Future of Multiple Access," 2020 IEEE International Conference on CommunicationsWorkshops (ICCWorkshops), 2020, pp. 1-6, doi: 10.1109/ICCWorkshops49005.2020.9145077.
 Mesleh, R, Haas, H, Ahn, CW & Yun, S 2006, Spatial Modulation – A New Low Complexity Spectral Efficiency Enhancing Technique. in IEEE International Conference on Communication and Networking in China (CHINACOM). pp. 1-5.
 R. Abu-alhiga and H. Haas, "Subcarrier-index modulation OFDM," in 2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, Sep. 2009, pp. 177–181.
 E. Basar, Ümit Aygölü, E. Panayirci, and H. V. Poor, "Orthogonal frequency division multiplexing with index modulation, "2012 IEEE Global Communications Conference (GLOBECOM), pp. 4741–4746, 2012.
 M. Jaradat, J. M. Hamamreh, and H. Arslan, "OFDM with subcarrier number modulation," IEEE Wireless Communications Letters, vol. 7, no. 6, pp. 914–917, Dec 2018.
 A. Jaradat, J. M. Hamamreh and H. Arslan, "Orthogonal Frequency Division Multiplexing With Subcarrier Gap Modulation," 2020 IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications, 2020, pp. 1-6, doi: 10.1109/PIMRC48278.2020.9217187.
 A. Jaradat, J. Hamamreh, and H. Arslan, "Modulation options for OFDM-based waveforms: Classification, comparison, and future directions, "IEEE Access, vol. 7, pp. 17 263–17 278, 2019.
 Hamamreh, J. M., Abewa, M., & Lemayian, J. P. (2020). New Non-Orthogonal Transmission Schemes for Achieving Highly Efficient, Reliable, and Secure Multi-User Communications. RS Open Journal on Innovative Communication Technologies, 1(2). https://doi.org/10.46470/03d8ffbd.324cc0fb
 Lemayian, J. P., & Hamamreh, J. M. (2020). A Novel Small-Scale Non-orthogonal Communication Technique Using Auxiliary Signal Superposition with Enhanced Security for Future Wireless Networks. RS Open Journal on Innovative Communication Technologies, 1(2). https://doi.org/10.46470/03d8ffbd.86b0d106
 J. P. Lemayian and J. M. Hamamreh, "Novel Small-Scale NOMA Communication Technique Using Auxiliary Signal Superposition," 2020 International Conference on UK-China Emerging Technologies (UCET), 2020, pp. 1-4, doi: 10.1109/UCET51115.2020.9205475.
 Zia, M. F., & Hamamreh, J. M. (2020). An Advanced Non-Orthogonal Multiple Access Security Technique for Future Wireless Communication Networks. RS Open Journal on Innovative Communication Technologies, 1(2). https://doi.org/10.46470/03d8ffbd.19888ce7
 Zia, M. F., Furqan, H. M., & Hamamreh, J. M. (2021). Multi-cell, Multiuser, and Multi-carrier Secure Communication Using Non-Orthogonal Signals’ Superposition with Dual-Transmission for IoT in 6G and Beyond. RS Open Journal on Innovative Communication Technologies, 2(3). https://doi.org/10.46470/03d8ffbd.08b7bd1d
 Abewa, M., & Hamamreh, J. M. (2021). Multi-User Auxiliary Signal Superposition Transmission (MU-AS-ST) for Secure and Low-Complexity Multiple Access Communications. RS Open Journal on Innovative Communication Technologies, 2(4). https://doi.org/10.46470/03d8ffbd.92a40b85
 Abewa, M., & Hamamreh, J. M. (2021). NC-OFDM-SPM: A Two-Dimensional Non-Coherent Modulation Scheme for Achieving the Coherent Performance of OFDM along with Sending an Additional Datastream. RS Open Journal on Innovative Communication Technologies, 2(3). https://doi.org/10.46470/03d8ffbd.a97a5236
 Hamamreh JM, Hajar A, Abewa M. Orthogonal frequency division multiplexing with subcarrier power modulation for doubling the spectral efficiency of 6G and beyond networks. Trans Emerging Tel Tech.2020;31:e3921. https://doi.org/10.1002/ett.3921