On Outage Analysis of OTFS Based LEO-Satellite Systems With HAPS Relaying

TL;DR

This paper investigates the use of OTFS waveform and HAPS relaying to improve communication reliability in LEO satellite systems, deriving outage probability expressions and demonstrating performance gains through simulations.

Contribution

It introduces a novel outage analysis for OTFS-based LEO satellite systems with HAPS relaying, including closed-form outage probability expressions under practical fading models.

Findings

Outage probability decreases with higher OTFS order.

Increasing transmit antennas improves system reliability.

HAPS relaying effectively mitigates Doppler and path loss effects.

Abstract

This paper presents an Orthogonal Time Frequency Space (OTFS) waveform application along with a high altitude platform station (HAPS) relaying for remedying severe Doppler effects in non-terrestrial networks (NTNs). Taking practical challenges into consideration, HAPS is exploited as a decode and forward relay node to mitigate the high path loss between a satellite and a base station (BS). In addition, a maximum ratio transmission scheme with multiple antennas at the LEO-satellite is utilized to maximize Signal-to-Noise Ratio (SNR). A shadowed Rician fading model is employed for the channel realization between the LEO-satellite and the HAPS while Nakagami-m is used between the HAPS and the BS. We derive the closed-form expression of the outage probability (OP) for the end-to-end system. The theoretical and simulation results demonstrate that the OP can significantly decrease when the OTFS order and the number of transmit antennas increase.