WOS1 – Wireless, Optical and Satellite Networks
Wednesday, 3 June 2026, 8:30-10:00, room Sala 5 (1st floor)
Session Chair:David Larrabeiti (Universidad Carlos III de Madrid, ES)
Reinforcement Learning-Based Traffic Steering for TN-NTN Integrated DualSteer Systems
Jimin Jeon (Electronics and Telecommunications Research Institute (ETRI), Korea (South)); Sung Hyuk Byun, HyunKyung Yoo and Seokwon Jang (Electronics and Telecommunications Research Institute, Korea (South)); Namseok Ko (ETRI, Korea (South))
Integrating terrestrial networks (TN) with non-terrestrial networks (NTN) is a key enabler of ubiquitous 6G connectivity, yet exploiting both paths simultaneously remains challenging due to the disparity in latency and channel dynamics between the two access types. Leveraging the 3GPP Release 19 DualSteer architecture, in which user equipment (UE) maintains concurrent sessions on both TN and NTN, this paper proposes a reinforcement learning (RL)-based traffic steering method that dynamically selects the optimal downlink path. We formulate the multi-user steering problem as a Markov decision process and design a Deep Q-Network (DQN) agent whose reward function maximizes reliability-to-latency efficiency, jointly capturing packet loss rate (PLR) and round-trip time (RTT). Simulation results show that the proposed method reduces PLR by 79% relative to the 3GPP ATSSS Smallest Delay policy (Min-RTT) while achieving comparable performance to the computationally infeasible exhaustive search with up to 838 \times inference speedup, demonstrating that near-optimal reliability and latency are achievable in real time.
Non-Collocated Carrier Aggregation: A Unified L2 Architecture for 6G Multi-Node Connectivity
Norman Goris (Apple Inc, Germany); Ahmed Helmy (Apple Inc, USA); Amr Y. Mostafa (Apple Inc., Germany); Nil Zaev (Apple Technology Engineering B.V. & Co. KG, Germany); Hesham Elhelw (Apple Inc., Germany); Henning Sanneck (Apple Technology Engineering BV & Co KG, Germany); Ayman Naguib (Apple Inc., USA)
Multi-node spectrum aggregation is a prerequisite for future 6G heterogeneous networks to address the dichotomy of spectrum fragmentation and coverage-capacity balancing. However, current 5G architectures: Carrier Aggregation (CA) and Dual Connectivity (DC) exhibit fundamental structural limitations when applied to non-collocated deployments with non-ideal transport latencies of 5-20 ms. CA fails due to strict HARQ timing, while DC suffers from control plane complexity and the “split bearer” inefficiency, where design with node-specific Radio Link Control (RLC) entities limits the possibility to correct flow split decisions by cross-node ARQ retransmissions. This paper presents Non-Collocated Carrier Aggregation (NC-CA), a unified framework combining CA’s protocol simplicity with DC’s deployment flexibility. NC-CA introduces the Uplink Control Group (UCG) concept to allow decoupling of HARQ loops from transport latency. Unlike the DC Cell Group concept, UCG is visible only in lower layers of the stack (Physical Layer and lower MAC). Simulations demonstrate that NC-CA maintains parity with DC (within 3%) while achieving better robustness under suboptimal routing. The framework supports 20 ms transport latency, delivering a substantial (up to ~45%) throughput gain for cell-edge users compared to single-node connectivity.
A Dual-Regulated Cascaded Random Access for LEO Satellite Networks
Wonho Lee and Gosan Noh (Hanbat National University, Korea (South)); Seong Ho Chae (Tech University of Korea, Korea (South)); Inkyu Bang and Taehoon Kim (Hanbat National University, Korea (South))
To address the massive access congestion resulting from the proliferation of Low Earth Orbit (LEO) satellite networks, this paper proposes a Dual-Regulated Cascaded Random Access (DR-CRA) scheme. The proposed scheme integrates the conventional 3GPP two-step and four-step random access procedures into a unified framework, focusing on the joint control of each stage via two regulation policies. Specifically, by dynamically adjusting the access probabilities of both stages, the scheme mitigates the inter-procedure coupling effect where congestion propagates from the first stage to the second. We perform mathematical analysis and simulations regarding access success probability and average service time. The results demonstrate that the proposed scheme significantly improves access success probability and effectively reduces service delay compared to conventional schemes.
Dynamic Access Point Sleep Mode Optimization for Energy-Efficient Cell-Free MIMO Networks
Ala Eddine Nouali (CEA-Leti, Grenoble, France); Mattia Merluzzi and Jean-Baptiste Doré (CEA-Leti, France); Jean-Paul Jamont (Université Grenoble Alpes, France)
Cell-free networks are dimensioned to meet peak-hour traffic demands, potentially causing over-dimensioning and energy inefficiency during off-peak periods. Access Point (AP) sleep-mode (SM) mechanisms can help reducing energy consumption in the long-term, if careful adaptation to traffic demands is performed. This requires a dynamic optimization able to cope with time-varying system parameters such as data arrivals and wireless channels. In this paper, we propose a user-centric clustering process, followed by an online optimization of AP SMs, precoding and power allocation, to minimize the long-term average energy consumption under network stability constraints. Lyapunov stochastic optimization is used to decouple the long-term problem into a sequence of deterministic problems based on instantaneous observations. Being the per-slot problem still non-convex and combinatorial, the dynamic SM decision is determined via principled heuristics and whale optimization algorithms, all guaranteeing stability. Simulation results demonstrate the effectiveness of the proposed method, also compared to a prohibitively complex exhaustive search. Under the same network configuration, we show that the cellular implementation fails to maintain network stability, highlighting the superiority of cell-free architectures in providing high data rates while ensuring long-term queue stability, with just enough involvement of APs.
Spectrum Sharing Optimization in NTN-TN Networks
Sirine Ben Ati (Interdisciplinary Centre for Security, Reliability, and Trust (SnT), Luxembourg); Flor Ortiz (Luxembourg Institute of Science and Technology, Luxembourg); Eva Lagunas (University of Luxembourg, Luxembourg); Joel Grotz (SES, Luxembourg); Symeon Chatzinotas (University of Luxembourg, Luxembourg)
The integration of Non-Terrestrial Networks (NTN) with Terrestrial Networks (TN) is essential for ubiquitous sixth-generation (6G) connectivity, enabling seamless communication across different types of satellites, Unmanned Aerial Vehicles (UAVs), and terrestrial infrastructure. However, NTN-TN networks face critical challenges, including dynamic spectrum allocation, interference management, and energy-efficient processing in power-constrained environments. This paper proposes an NTN TN 6G coexistence scenario where TNs and a low earth orbit (LEO) satellite use the same C-band frequency. The goal is to maximize the total NTN capacity given a traffic demand map in order to determine the optimal resource blocks (RBs) allocation for NTN. To address this problem, an efficient iterative algorithm is implemented. Simulations show the efficacy of the suggested approach and offer important insights into how TN interference affects LEO beams.
