BackCom Assisted Hybrid NOMA Uplink Transmission for Ambient IoT

TL;DR

This paper focuses on the application of H-NOMA to ambient Internet of Things (IoT) with energy-constrained devices, where a new backscatter communication (BackCom) assisted H-NOMA uplink scheme is developed.

Abstract

Hybrid non-orthogonal multiple access (H-NOMA) has recently received significant attention as a general framework of multiple access, where both conventional orthogonal multiple access (OMA) and pure NOMA are its special cases. This paper focuses on the application of H-NOMA to ambient Internet of Things (IoT) with energy-constrained devices, where a new backscatter communication (BackCom) assisted H-NOMA uplink scheme is developed. Resource allocation for H-NOMA uplink transmission is also considered, where an overall power minimization problem is formulated. Insightful understandings for the key features of BackCom assisted H-NOMA and its difference from conventional H-NOMA are illustrated by developing analytical results for the two-user special case. For the general multi-user scenario, two algorithms, one based on the branch-bound (BB) principle and the other based on successive convex approximation (SCA), are developed to realize different tradeoffs between the system performance and complexity. The numerical results are also provided to verify the accuracy of the developed analytical results and demonstrate the performance gain of H-NOMA over OMA.

Figures (6)

• Figure 1: Overall power consumption required by the considered transmission schemes, where $M=2$, the noise power is set as $\sigma^2=10^{-8}$, and NPCU denotes nats per channel use.
• Figure 2: Overall power consumption required by the considered transmission schemes, where $M=2$, and the noise power is set as $\sigma^2=10^{-7}$.
• Figure 3: Probability of the five NOMA solutions to become the optimal solution, where the two pure NOMA solutions from Lemma \ref{['lemma3']}, denoted by P-NOMA Types I and II, respectively, and the three H-NOMA solutions from Lemma \ref{['lemma4']}, denoted by H-NOMA Types I II and III, respectively, are used. $M=2$, $\sigma^2=10^{-8}$, $r_u=2$ m, and $r_c=15$ m.
• Figure 4: Overall power consumption required by the considered transmission schemes in the multi-user scenario, where $R=4$ NPCU and the noise power is set as $\sigma^2=10^{-8}$.
• Figure 5: Overall power consumption required by the considered transmission schemes as a function of the target data rate, where $M=5$, the noise power is set as $\sigma^2=10^{-8}$, and $r_u=5$ m.

Theorems & Definitions (4)

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