Interference is a limiting factor in the emerging dense low Earth orbit (LEO) networks. In the LEO network, the interference is spatially and temporally correlated. At narrow-beam LEO base stations (BSs), spatial interference can vary significantly, and multipath fading introduces temporal variation. While developing novel stochastic geometry analysis in a multibeam scenario, we explore spatio-temporal interference correlation in the LEO uplink. We derive a closed-form expression for the spatio-temporal interference correlation coefficient. As an application of the analysis, we show that the signal-to-interference ratio (SIR) entails significant spatial clustering. In this regard, we demonstrate that an appropriately designed grant-free random access scheme, particularly slotted ALOHA, can mitigate spatial SIR clustering over the beams while preserving average throughput. Furthermore, we propose a novel gamma distribution model for the interference power distribution and a Lomax distribution model for the SIR.
Grant-Free (GF) random access is promising for low Earth orbit satellite Internet due to its reduced access latency. However, existing schemes suffer from poor performance in massive connectivity scenarios. To address this challenge, we firstly propose an iterative residual feedb…
We investigate SIR distributions and order statistics of user equipments (UEs) at a typical low Earth orbit satellite base station (LEO BS) with narrow Gaussian antenna beams in the uplink. We analyze SIR distributions for the three strongest UEs under successive interference can…
As low Earth orbit (LEO) satellite communications take shape on a global scale, system-level evaluation has become essential for a rigorous understanding of their performance characteristics. Most existing studies have relied on a full-buffer assumption, which obscures the hetero…
Ambient Internet of Things (A-IoT) deployments impose stringent hardware constraints, including low-order modulations and simple transceiver architectures. We propose a tensor-based grant-free random access scheme for the initial access message (Msg1) tailored to these limitation…
Coherent free-space optical (FSO) communication is a promising solution for low Earth orbit (LEO) satellite downlink transmission. However, high orbital velocity introduces multi-GHz Doppler shifts that appear as a rapidly time-varying carrier frequency offset (CFO), which is a m…
Electroencephalography (EEG) is widely used to diagnose neurological conditions, but its analysis usually relies on either predefined spectral features or deep neural networks. Predefined features carry a strong bias, since they fix in advance what counts as informative, while de…