Telecommunications
Physics-Informed Neural Networks for MIMO Beam Map and Environment Reconstruction
Chen, Wangqian, Chen, Junting, Cui, Shuguang
As communication networks evolve towards greater complexity (e.g., 6G and beyond), a deep understanding of the wireless environment becomes increasingly crucial. When explicit knowledge of the environment is unavailable, geometry-aware feature extraction from channel state information (CSI) emerges as a pivotal methodology to bridge physical-layer measurements with network intelligence. This paper proposes to explore the received signal strength (RSS) data, without explicit 3D environment knowledge, to jointly construct the radio beam map and environmental geometry for a multiple-input multiple-output (MIMO) system. Unlike existing methods that only learn blockage structures, we propose an oriented virtual obstacle model that captures the geometric features of both blockage and reflection. Reflective zones are formulated to identify relevant reflected paths according to the geometry relation of the environment. We derive an analytical expression for the reflective zone and further analyze its geometric characteristics to develop a reformulation that is more compatible with deep learning representations. A physics-informed deep learning framework that incorporates the reflective-zone-based geometry model is proposed to learn the blockage, reflection, and scattering components, along with the beam pattern, which leverages physics prior knowledge to enhance network transferability. Numerical experiments demonstrate that, in addition to reconstructing the blockage and reflection geometry, the proposed model can construct a more accurate MIMO beam map with a 32%-48% accuracy improvement.
Better Together: Leveraging Multiple Digital Twins for Deployment Optimization of Airborne Base Stations
Belgiovine, Mauro, Dick, Chris, Chowdhury, Kaushik
Abstract--Airborne Base Stations (ABSs) allow for flexible geographical allocation of network resources with dynamically changing load as well as rapid deployment of alternate connectivity solutions during natural disasters. Since the radio infrastructure is carried by unmanned aerial vehicles (UA Vs) with limited flight time, it is important to establish the best location for the ABS without exhaustive field trials. This paper proposes a digital twin (DT)-guided approach to achieve this goal through the following key contributions: (i) Implementation of an interactive software bridge between two open-source DTs such that the same scene is evaluated with high fidelity across NVIDIA's Sionna and Aerial Omniverse Digital Twin (AODT), highlighting the unique features of each of these platforms for this allocation problem, (ii) Design of a back-propagation-based algorithm in Sionna for rapidly converging on the physical location of the UA Vs, orientation of the antennas and transmit power to ensure efficient coverage across the swarm of the UA Vs, and (iii) numerical evaluation in AODT for large network scenarios (50 UEs, 10 ABS) that identifies the environmental conditions in which there is agreement or divergence of performance results between these twins. Finally, (iv) we propose a resilience mechanism to provide consistent coverage to mission-critical devices and demonstrate a use case for bi-directional flow of information between the two DTs. Unmanned Aerial V ehicle (UA V)-mounted Base Stations, or Airborne Base Stations (ABSs), have gained significant attention as a complement to ground-based cellular networks [1]. As UA Vs become more accessible, their ability to navigate 3-dimensional (3D) space provides flexibility in adapting to dynamic network demands [2], [3], enabling line-of-sight links to mission-critical units [4] and enhancing user tracking [5]. However, ABS-enabled connectivity introduces challenges such as collision avoidance, coordinated coverage, and optimal placement, considering limited flight times of 20 to 100 minutes [6]. These challenges are highly dependent on the RF propagation environment, making prior channel knowledge essential for effective network planning. Motivation for Digital Twins: Optimal placement of Base Stations (BSs) is traditionally handled by telecom operators relying on domain knowledge and best practices. Digital Twins (DTs) and, specifically, Digital Twins for Networking (DTNs) [7], have emerged as strategic tools for network simulation, performance analysis, and "what-if" scenarios.
Learning Decentralized Routing Policies via Graph Attention-based Multi-Agent Reinforcement Learning in Lunar Delay-Tolerant Networks
Lozano-Cuadra, Federico, Soret, Beatriz, Net, Marc Sanchez, Cauligi, Abhishek, Rossi, Federico
Abstract-- We present a fully decentralized routing framework for multi-robot exploration missions operating under the constraints of a Lunar Delay-T olerant Network (LDTN). In this setting, autonomous rovers must relay collected data to a lander under intermittent connectivity and unknown mobility patterns. We formulate the problem as a Partially Observable Markov Decision Problem (POMDP) and propose a Graph Attention-based Multi-Agent Reinforcement Learning (GA T - MARL) policy that performs Centralized Training, Decentralized Execution (CTDE). Our method relies only on local observations and does not require global topology updates or packet replication, unlike classical approaches such as shortest path and controlled flooding-based algorithms. Through Monte Carlo simulations in randomized exploration environments, GA T -MARL provides higher delivery rates, no duplications, and fewer packet losses, and is able to leverage short-term mobility forecasts; offering a scalable solution for future space robotic systems for planetary exploration, as demonstrated by successful generalization to larger rover teams. The renewed interest in planetary and lunar surface exploration has accelerated the development of autonomous multi-robot systems.
Large Multimodal Models-Empowered Task-Oriented Autonomous Communications: Design Methodology and Implementation Challenges
Yang, Hyun Jong, Kim, Hyunsoo, Noh, Hyeonho, Kim, Seungnyun, Shim, Byonghyo
Notice: This work has been submitted to the IEEE for possible publication. Abstract--Large language models (LLMs) and large multi-modal models (LMMs) have achieved unprecedented breakthrough, showcasing remarkable capabilities in natural language understanding, generation, and complex reasoning. This transformative potential has positioned them as key enablers for 6G autonomous communications among machines, vehicles, and humanoids. In this article, we provide an overview of task-oriented autonomous communications with LLMs/LMMs, focusing on multimodal sensing integration, adaptive reconfiguration, and prompt/fine-tuning strategies for wireless tasks. We demonstrate the framework through three case studies: LMM-based traffic control, LLM-based robot scheduling, and LMM-based environment-aware channel estimation. From experimental results, we show that the proposed LLM/LMM-aided autonomous systems significantly outperform conventional and discriminative deep learning (DL) model-based techniques, maintaining robustness under dynamic objectives, varying input parameters, and heterogeneous multimodal conditions where conventional static optimization degrades. Driven by the huge success of ChatGPT, large language models (LLMs) have gained widespread attention, reshaping various fields by solving problems with zero-shot or few-shot prompting. Recently, large multimodal models (LMMs) extend this capability by embracing various modalities such as images, videos, and audio. These models can handle changing objectives and input variations using diverse multimodal observations.
ixi-GEN: Efficient Industrial sLLMs through Domain Adaptive Continual Pretraining
Kim, Seonwu, Na, Yohan, Kim, Kihun, Cho, Hanhee, Lim, Geun, Kim, Mintae, Park, Seongik, Kim, Ki Hyun, Han, Youngsub, Jeon, Byoung-Ki
The emergence of open-source large language models (LLMs) has expanded opportunities for enterprise applications; however, many organizations still lack the infrastructure to deploy and maintain large-scale models. As a result, small LLMs (sLLMs) have become a practical alternative despite inherent performance limitations. While Domain Adaptive Continual Pretraining (DACP) has been explored for domain adaptation, its utility in commercial settings remains under-examined. In this study, we validate the effectiveness of a DACP-based recipe across diverse foundation models and service domains, producing DACP-applied sLLMs (ixi-GEN). Through extensive experiments and real-world evaluations, we demonstrate that ixi-GEN models achieve substantial gains in target-domain performance while preserving general capabilities, offering a cost-efficient and scalable solution for enterprise-level deployment.
Bridging Earth and Space: A Survey on HAPS for Non-Terrestrial Networks
Svistunov, G., Akhtarshenas, A., López-Pérez, D., Giordani, M., Geraci, G., Yanikomeroglu, H.
HAPS are emerging as key enablers in the evolution of 6G wireless networks, bridging terrestrial and non-terrestrial infrastructures. Operating in the stratosphere, HAPS can provide wide-area coverage, low-latency, energy-efficient broadband communications with flexible deployment options for diverse applications. This survey delivers a comprehensive overview of HAPS use cases, technologies, and integration strategies within the 6G ecosystem. The roles of HAPS in extending connectivity to underserved regions, supporting dynamic backhauling, enabling massive IoT, and delivering reliable low-latency communications for autonomous and immersive services are discussed. The paper reviews state-of-the-art architectures for terrestrial and non-terrestrial network integration, highlights recent field trials. Furthermore, key enabling technologies such as channel modeling, AI-driven resource allocation, interference control, mobility management, and energy-efficient communications are examined. The paper also outlines open research challenges. By addressing existing gaps in the literature, this survey positions HAPS as a foundational component of globally integrated, resilient, and sustainable 6G networks.
SoftBank seeks to sell about 2 billion of bonds amid AI push
SoftBank has raised at least $24 billion in loans and bonds so far in 2025 and is seeking to raise more in the overseas bond market. SoftBank Group is returning to the overseas bond market for the second time this year amid an aggressive fundraising push for artificial intelligence, led by its bet on OpenAI. The Japanese technology investment giant is looking to raise about $1.5 billion to $2 billion in the dollar debt market, and about €500 million ($580 million) from euro-denominated notes, according to people familiar with the matter. A spokesperson for SoftBank said the bond deal size hasn't been finalized, declining to comment further. With a heavy emphasis on new AI investments, SoftBank's billionaire founder Masayoshi Son has pledged as much as $500 billion for a project known as Stargate and announced a planned $30 billion stake in OpenAI earlier this year.
On AI Verification in Open RAN
Soundrarajan, Rahul, Fiandrino, Claudio, Polese, Michele, D'Oro, Salvatore, Bonati, Leonardo, Melodia, Tommaso
Open RAN introduces a flexible, cloud-based architecture for the Radio Access Network (RAN), enabling Artificial Intelligence (AI)/Machine Learning (ML)-driven automation across heterogeneous, multi-vendor deployments. While EXplainable Artificial Intelligence (XAI) helps mitigate the opacity of AI models, explainability alone does not guarantee reliable network operations. In this article, we propose a lightweight verification approach based on interpretable models to validate the behavior of Deep Reinforcement Learning (DRL) agents for RAN slicing and scheduling in Open RAN. Specifically, we use Decision Tree (DT)-based verifiers to perform near-real-time consistency checks at runtime, which would be otherwise unfeasible with computationally expensive state-of-the-art verifiers. We analyze the landscape of XAI and AI verification, propose a scalable architectural integration, and demonstrate feasibility with a DT-based slice-verifier. We also outline future challenges to ensure trustworthy AI adoption in Open RAN.
Accelerating Frontier MoE Training with 3D Integrated Optics
Bernadskiy, Mikhail, Carson, Peter, Graham, Thomas, Groves, Taylor, Lee, Ho John, Yeh, Eric
--The unabated growth in AI workload demands is driving the need for concerted advances in compute, memory, and interconnect performance. As traditional semiconductor scaling slows, high-speed interconnects have emerged as the new scaling engine, enabling the creation of larger logical GPUs by linking many GPUs into a single, low-latency, high-bandwidth compute domain. While initial scale-up fabrics leveraged copper interconnects for their power and cost advantages, the maximum reach of passive electrical interconnects (approximately 1 meter) effectively limits the scale-up domain to within a single rack. The advent of 3D-stacked optics and logic offers a transformative, power-efficient scale-up solution for connecting hundreds of GPU packages (thousands of GPUs) across multiple data center racks. This work explores the design tradeoffs of scale-up technologies and demonstrates how frontier LLMs necessitate novel photonic solutions to achieve aggressive power and performance targets. We model the benefits of 3D CPO (Passage) enabled GPUs and switches within the scale-up domain when training Frontier Mixture of Experts (MoE) models exceeding one trillion parameters. Our results show that the substantial increases in bandwidth and radix enabled by 3D CPO allow for an 8X increase in scale-up capability. The race to build larger, more sophisticated AI models is pushing the limits of existing infrastructure. At the chip and package level, GPUs are constrained by shoreline, yields and power. These challenges have led to the development of large high-bandwidth, low-latency scale-up pods. These pods effectively combine hundreds of GPUs into a single logical GPU to facilitate a variety of parallelism strategies (e.g. Approaches like Mixture of Experts (MoE) [1] have pushed scale-up networks to their limits due to copper reach (1 meter), which constrains the number of GPUs that can be connected within a single network hop. With MoEs, an ensemble of specialized sub-networks work together through sparse activations to increase model capacity without significantly increasing computational requirements. The output of the selected experts are combined to create the final result.
A Primer on Kolmogorov-Arnold Networks (KANs) for Probabilistic Time Series Forecasting
Vaca-Rubio, Cristian J., Pereira, Roberto, Blanco, Luis, Zeydan, Engin, Caus, Màrius
This work introduces Probabilistic Kolmogorov-Arnold Network (P-KAN), a novel probabilistic extension of Kolmogorov-Arnold Networks (KANs) for time series forecasting. By replacing scalar weights with spline-based functional connections and directly parameterizing predictive distributions, P-KANs offer expressive yet parameter-efficient models capable of capturing nonlinear and heavy-tailed dynamics. We evaluate P-KANs on satellite traffic forecasting, where uncertainty-aware predictions enable dynamic thresholding for resource allocation. Results show that P-KANs consistently outperform Multi Layer Perceptron (MLP) baselines in both accuracy and calibration, achieving superior efficiency-risk trade-offs while using significantly fewer parameters. We build up P-KANs on two distributions, namely Gaussian and Student-t distributions. The Gaussian variant provides robust, conservative forecasts suitable for safety-critical scenarios, whereas the Student-t variant yields sharper distributions that improve efficiency under stable demand. These findings establish P-KANs as a powerful framework for probabilistic forecasting with direct applicability to satellite communications and other resource-constrained domains.