Multi-User OFDM-SNM is proposed in this paper for serving multiple users by dedicating the subcarriers used for implementing SNM to serve a far user, whereas the remaining subcarriers, which are used to be inactive in conventional OFDM-SNM, are used to send data for a near user.
Orthogonal Frequency Division Multiplexing with Subcarrier Number Modulation (OFDM-SNM) has recently been proposed as an effective transmission method that can transmit additional data bits by exploiting the number of subcarriers in each subblock. This results in an improved performance in terms of spectral efficiency and reliability. However, one of the main drawbacks of OFDM-SNM is that not all the available subcarriers are deployed to transmit data, as some of these subcarriers remain inactive. In order to eliminate this problem and make use of all the available subcarriers, Multi-User OFDM-SNM is proposed in this paper for serving multiple users by dedicating the subcarriers used for implementing SNM to serve a far user, whereas the remaining subcarriers are used to send data for a near user. In this paper, the concept of multi-user OFDM-SNM is established on the basis of conventional OFDM over a Rayleigh fading channel. The validity of the system is proven by exhibiting both theoretical analysis and computer simulations. The obtained results show that the proposed multi-user OFDM-SNM is a strong candidate for the future 6G and beyond technologies and it can satisfy the requirements of multi-user cases of future wireless systems demanding higher reliability and better spectral efficiency.
Keywords: OFDM, OFDM-SNM, subcarrier number modulation, wireless communication, 5G, 6G, multi-user, future wireless networks.