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NOMA Design with Power-Outage Tradeoff for Two-User Systems

Zeyu Sun, Yindi Jing, Xinwei Yu

TL;DR

The results show that the average required transmit power grows logarithmically in the reciprocal of the ACC threshold and a non-zero threshold is necessary for finite average transmit power.

Abstract

This letter proposes a modified non-orthogonal multiple-access (NOMA) scheme for systems with a multi-antenna base station (BS) and two single-antenna users, where NOMA transmissions are conducted only when the absolute correlation coefficient (CC) between the user channels exceeds a threshold and the BS uses matched-filter (MF) precoding along the user with the stronger average channel gain. We derive the average minimal transmit power to guarantee the signal-to-interference-plus-noise-ratio (SINR) levels of both users. Our results show that the average minimal power grows logarithmically in the reciprocal of the CC threshold and a non-zero threshold is necessary for the modified NOMA scheme to have finite average minimal transmit power. Further, for the massive MIMO scenario, we derive the scaling laws of the average transmit power and outage probability with respect to the antenna numbers, as well as their tradeoff law. Simulation results are shown to validate our theoretical results.

NOMA Design with Power-Outage Tradeoff for Two-User Systems

TL;DR

The results show that the average required transmit power grows logarithmically in the reciprocal of the ACC threshold and a non-zero threshold is necessary for finite average transmit power.

Abstract

This letter proposes a modified non-orthogonal multiple-access (NOMA) scheme for systems with a multi-antenna base station (BS) and two single-antenna users, where NOMA transmissions are conducted only when the absolute correlation coefficient (CC) between the user channels exceeds a threshold and the BS uses matched-filter (MF) precoding along the user with the stronger average channel gain. We derive the average minimal transmit power to guarantee the signal-to-interference-plus-noise-ratio (SINR) levels of both users. Our results show that the average minimal power grows logarithmically in the reciprocal of the CC threshold and a non-zero threshold is necessary for the modified NOMA scheme to have finite average minimal transmit power. Further, for the massive MIMO scenario, we derive the scaling laws of the average transmit power and outage probability with respect to the antenna numbers, as well as their tradeoff law. Simulation results are shown to validate our theoretical results.

Paper Structure

This paper contains 8 sections, 5 theorems, 31 equations, 3 figures.

Table of Contents

  1. Introduction
  2. NOMA scheme with Correlation Threshold
  3. Average Minimal Transmit Power with SINR Guarantee
  4. Numerical Result
  5. Conclusion
  6. Proof of Theorem \ref{['thm-1']}
  7. Proof of Corollary \ref{['lemma-1']}
  8. Proof of Corollary \ref{['col-4']}

Key Result

Theorem 1

Define where $F(\cdot,\cdot;\cdot;\cdot)$ is the hypergeometric function and $\rho_{th}$ is the CC threshold. The average minimal transmit power for CB-NOMA to guarantee SINR levels of both users, $\gamma_1$ and $\gamma_2$, has the following lower and upper bounds:

Figures (3)

  • Figure 1: Average minimal power versus $\rho_{th}^2$ where $M=8$ and $16$, $\beta_1=0$dB, $\beta_2=-10$dB, $\gamma_1=10$dB, $\gamma_2=0$dB.
  • Figure 2: Average minimal power versus $M$ where $\rho_{th}^2=0.02$ and $0.005$, $\beta_1=0$dB, $\beta_2=-10$dB, $\gamma_1=10$dB, $\gamma_2=0$dB.
  • Figure 3: Average minimal power versus $M$ where $\rho_{th}^2=1/M^{\tau}$, $\beta_1=0$dB, $\beta_2=-10$dB, $\gamma_1=10$dB, $\gamma_2=0$dB

Theorems & Definitions (5)

  • Theorem 1
  • Corollary 1
  • Corollary 2
  • Corollary 3
  • Corollary 4