Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Performance Analysis of Flexible Duplex Inter-Satellite Links in LEO Networks

Yomali Lokugama, Charith Dissanayake, Saman Atapattu, Kandeepan Sithamparanathan

Abstract

This paper investigates energy-efficient inter-satellite communication in Low Earth Orbit (LEO) networks, where satellites exchange both buffered and newly generated data through half-duplex inter-satellite links (ISLs). Due to orbital motion and interference-prone directional asymmetry, the achievable ISL capacities in opposite directions vary dynamically, leading to inefficient utilization under conventional fixed or alternating duplex modes. To address this, we propose a Flexible Duplex (FlexD) scheme that adaptively selects the ISL transmission direction in each slot to maximize instantaneous end-to-end sky-to-ground throughput, jointly accounting for ISL quality, downlink conditions, and queue backlogs. A unified analytical framework is developed that transforms the bottleneck rate structure into an equivalent SINR domain, enabling closed-form derivations of throughput outage probability and energy efficiency under deterministic ISLs and Rician satellite-to-ground fading. The analysis reveals distinct operating regions governed by ISL and backlog constraints and provides tractable bounds for ergodic rate and energy efficiency. Numerical results confirm that FlexD achieves higher reliability and up to 30% improvement in energy efficiency compared with conventional half- and full-duplex schemes under realistic inter-satellite interference conditions.

Performance Analysis of Flexible Duplex Inter-Satellite Links in LEO Networks

Abstract

This paper investigates energy-efficient inter-satellite communication in Low Earth Orbit (LEO) networks, where satellites exchange both buffered and newly generated data through half-duplex inter-satellite links (ISLs). Due to orbital motion and interference-prone directional asymmetry, the achievable ISL capacities in opposite directions vary dynamically, leading to inefficient utilization under conventional fixed or alternating duplex modes. To address this, we propose a Flexible Duplex (FlexD) scheme that adaptively selects the ISL transmission direction in each slot to maximize instantaneous end-to-end sky-to-ground throughput, jointly accounting for ISL quality, downlink conditions, and queue backlogs. A unified analytical framework is developed that transforms the bottleneck rate structure into an equivalent SINR domain, enabling closed-form derivations of throughput outage probability and energy efficiency under deterministic ISLs and Rician satellite-to-ground fading. The analysis reveals distinct operating regions governed by ISL and backlog constraints and provides tractable bounds for ergodic rate and energy efficiency. Numerical results confirm that FlexD achieves higher reliability and up to 30% improvement in energy efficiency compared with conventional half- and full-duplex schemes under realistic inter-satellite interference conditions.
Paper Structure (20 sections, 2 theorems, 24 equations, 2 figures)

This paper contains 20 sections, 2 theorems, 24 equations, 2 figures.

Table of Contents

  1. Introduction
  2. System Model
  3. Constellation, Geographic Partition, and Time
  4. Communication Flows and the Two-Hop Delivery Problem
  5. Proposed Flexible Duplex (FlexD) for ISLs
  6. Directional ISL Asymmetry and Motivation
  7. FlexD Direction Selection
  8. SINR Analysis and Physical-Layer Model
  9. From Bottleneck Rates to SINR Equivalents
  10. Deterministic ISL Link SINR: $S_\ell\!\to\!S_k$
  11. Random Downlink SINR: $S_k\!\to\!U_\ell$
  12. FlexD System Performance Analysis
  13. Throughput Outage Probability
  14. Energy Efficiency (EE)
  15. Extension to NLoS, Multiuser, and Multihop Scenarios
  16. ...and 5 more sections

Key Result

Lemma 1

The system outage probability $P_{\mathrm{o}}=\Pr(\Gamma\le\zeta)$ is expressed as where $F_X(\cdot,\cdot)$ denotes the Rician CDF defined in eq:cdf_rice. The deterministic cut levels are and $\Omega_{\min}=\min(\Omega_{\ell},\Omega_{k})$, $\Omega_{\max}=\max(\Omega_{\ell},\Omega_{k})$.

Figures (2)

  • Figure 1: System architecture and motivation for the proposed FlexD scheme: (a) initial constellation configuration, (b) post-handover configuration, and (c) comparison of ISL capacities $C_{S_k\to S_\ell}$ and $C_{S_\ell\to S_k}$ under FlexD and conventional HD.
  • Figure 2: Performance comparison of FlexD with HD and FD baselines. (a) Lower outage via adaptive direction selection, (b) higher energy efficiency per unit power, and (c) robustness to dynamic channel and interference variations across slots.

Theorems & Definitions (6)

  • Remark 1: ISL Availability
  • Remark 2: Relation to SINR
  • Lemma 1: Throughput Outage Probability
  • Remark 3: Interpretation of Lemma 1 under No-Backlog Conditions
  • Lemma 2: Energy Efficiency
  • Remark 4: Energy-Efficiency Adaptability of FlexD