Comments on SIC design for SISO NOMA Systems over Doubly Selective Channels.

Abstract

<p>Non-orthogonal multiple access principle applied in power domain (power-domain NOMA) enhances spectrum efficiency and connectivity of mobile communication systems through sharing between Orthogonal Multiple Access (OMA) and other multiple users. It is the almost main current trend for research and standards for 5G and beyond. Spectrum sharing generates multi-users interference (Multiple Access Interference, MAI) which destroys orthogonality in OMA systems. Meanwhile the so-called Successive Interference Cancellation (SIC) techniques are used to suppress MAI and the Cognitive Radio (CR) principle (CR-NOMA) for decoding order for multiple users inspired effective SIC algorithms. The CR-NOMA principle is applied in the present material as well, but with significant changes for SIC design as for Doubly Selective channels. Due to the above reasons, two original SIC design methods are proposed hereafter following the CR-NOMA principle. Regarding to it the OMA signal (primary user) is decoded first using a Chaos-based quasi-optimum Extended Kalman Filter (EKF). The set of “secondary users” (multiusers) are proposed to be decoded secondly by the following two different methods:</p> <p>- Chaos-based EKF filters or , </p> <p>- Sequential <i>m</i> hypothesis testing.</p> <p> The proposed approach for SIC design is rather simple, fast and accurate for practical implementation.</p>

The Incoherent Approach Might Be Opportunistic for the 6G Wireless Dense Networks Design? Theoretic View

“…The SIC design has been thoroughly investigated and developed (see [1], [35], etc. ), is mainly based on the utilization of the SIC, SICT information, as it was already mentioned above (see section I); the low feasibility of an accurate user identification provoked therefore doubts regarding the application of the Power NOMA in MIMO transmission systems, particularly in Double Selective channels.…”

“…It might be achieved through the application of sequential m-hypothesis testing algorithms. As it was known for a long time, they are characterized by reduced processing times (see [35], [36] and references therein). The latter is detailed in [13], [35] and is omitted in the following.…”

“…It was also mentioned in [13], [35] that, for evaluation of the influence of the classification errors on the final noise immunity of the NOMA transmission system, the methodology of the Chernoff Upper bounds might be successfully applied together with the so-called minimum Kullback-Leibler distance between Gaussian hypothesis in Double Selective channels for the scenarios of significant difference between them. Finally, it was shown, that the classification error is much less than the Error Probabilityerr P of the system and it might be neglected [13].…”