Double Differential Modulation-Based Non-Orthogonal Multiple Access

This letter presents a non-orthogonal multiple access approach for a near-far user scenario through a novel double differential (DD) modulation-based scheme. With the help of DD modulation, the requirement of channel state information for decoding and interference cancellation is eliminated. Also, in the presence of carrier frequency offset, the proposed scheme demonstrates a robust performance. Through rigorous theoretical analysis, we derive closed-form expressions for the error rates of both users, enabling the design of an optimized power allocation strategy. Surprisingly, allocating more power to the far user not only enhances its performance but also improves interference cancellation for the near user. Simulations validate our findings, showing significant performance gains as compared to existing methods.