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Single-Waveguide Multiple-Pinching-Antenna Systems: OMA versus NOMA

Yanyu Cheng, Hao Li, Zhen Wang, Zhiguo Ding

Abstract

This paper investigates the performance of a pinching-antenna (PA) system with a signal waveguide and multiple pinching antennas to serve users distributed across multiple rooms. The performance of the system is evaluated through a comparative analysis under both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) schemes. Specifically, this paper derives closed-form expressions for the outage probability (OP) and ergodic rate (ER) in each scheme. Furthermore, asymptotic analyses are conducted to characterize the system behavior in the high signal-to-noise ratio (SNR) regime. Extensive Monte Carlo simulations are utilized to validate the accuracy of the analytical derivations. The comparative results can be summarized as follows: 1) in the downlink fixed-rate scenario, whether OMA or NOMA achieves better outage performance depends on system parameters, such as the number of users and power allocation coefficients; 2) in the uplink fixed-rate scenario, the outage performance of NOMA is inferior to that of OMA in the high-SNR regime, and the decay rate of the OP for NOMA users depends on the rate thresholds; and 3) for both uplink and downlink adaptive-rate scenarios, the rate performance comparison of the two schemes depends on system parameters in the low-SNR regime, whereas OMA generally outperforms NOMA in the high-SNR regime.

Single-Waveguide Multiple-Pinching-Antenna Systems: OMA versus NOMA

Abstract

This paper investigates the performance of a pinching-antenna (PA) system with a signal waveguide and multiple pinching antennas to serve users distributed across multiple rooms. The performance of the system is evaluated through a comparative analysis under both orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) schemes. Specifically, this paper derives closed-form expressions for the outage probability (OP) and ergodic rate (ER) in each scheme. Furthermore, asymptotic analyses are conducted to characterize the system behavior in the high signal-to-noise ratio (SNR) regime. Extensive Monte Carlo simulations are utilized to validate the accuracy of the analytical derivations. The comparative results can be summarized as follows: 1) in the downlink fixed-rate scenario, whether OMA or NOMA achieves better outage performance depends on system parameters, such as the number of users and power allocation coefficients; 2) in the uplink fixed-rate scenario, the outage performance of NOMA is inferior to that of OMA in the high-SNR regime, and the decay rate of the OP for NOMA users depends on the rate thresholds; and 3) for both uplink and downlink adaptive-rate scenarios, the rate performance comparison of the two schemes depends on system parameters in the low-SNR regime, whereas OMA generally outperforms NOMA in the high-SNR regime.

Paper Structure

This paper contains 39 sections, 16 theorems, 59 equations, 8 figures, 1 table.

Table of Contents

  1. Introduction
  2. Related Work
  3. Conventional Flexible Antenna Systems
  4. Pinching Antenna Systems
  5. Motivation and Contributions
  6. System Model
  7. Downlink
  8. OMA
  9. NOMA
  10. Uplink
  11. OMA
  12. NOMA
  13. Performance Analysis of Downlink Transmission
  14. OMA
  15. Distance Statistics
  16. ...and 24 more sections

Key Result

Lemma 1

Let $Z_1 = | \psi_{m}^{Pin} - \psi_m |^{2}$, where $\psi_m^{Pin} = [x_m, 0, d]$, $\psi_m = [x_m, y_m, 0]$, $\forall m$. Its PDF and CDF are given by and respectively. $\blacktriangleleft$$\blacktriangleleft$

Figures (8)

  • Figure 1: A pinching-antenna system with single waveguide and multiple pinching antennas.
  • Figure 2: Outage probability versus SNR for downlink OMA and NOMA systems. (a) illustrates the OMA system performance for $M=2$ and $M=5$, respectively. (b) illustrates the NOMA system in a two-user scenario.
  • Figure 3: Outage probability versus SNR for downlink OMA and NOMA systems. (a) and (b) illustrate case 1 and case 2 in \ref{['SubSection:downlink-NOMA-OP-compare']}, respectively.
  • Figure 4: Ergodic rate versus SNR in the downlink. (a) illustrates the OMA system performance for $M=2$ and $M=5$, respectively. (b) illustrates the NOMA system in a two-user scenario.
  • Figure 5: Ergodic rate versus SNR for downlink OMA and NOMA systems, where $M=2$.
  • ...and 3 more figures

Theorems & Definitions (32)

  • Lemma 1
  • Theorem 1
  • proof
  • Proposition 1
  • proof
  • Theorem 2
  • proof
  • Proposition 2
  • proof
  • Corollary 1
  • ...and 22 more