Wireless channel modeling plays a pivotal role in designing, analyzing, and optimizing wireless communication systems. Nevertheless, developing an effective channel modeling approach has been a long-standing challenge. This issue has been escalated due to denser network deployment, larger antenna arrays, and broader bandwidth in next-generation networks. To address this challenge, we put forth WRF-GS, a novel framework for channel modeling based on wireless radiation field (WRF) reconstruction using 3D Gaussian splatting (3D-GS). WRF-GS employs 3D Gaussian primitives and neural networks to capture the interactions between the environment and radio signals, enabling efficient WRF reconstruction and visualization of the propagation characteristics. The reconstructed WRF can then be used to synthesize the spatial spectrum for comprehensive wireless channel characterization. While WRF-GS demonstrates remarkable effectiveness, it faces limitations in capturing high-frequency signal variations caused by complex multipath effects. To overcome these limitations, we propose WRF-GS+, an enhanced framework that integrates electromagnetic wave physics into the neural network design. WRF-GS+ leverages deformable 3D Gaussians to model both static and dynamic components of the WRF, significantly improving its ability to characterize signal variations. In addition, WRF-GS+ accelerates the splatting process by simplifying the 3D-GS modeling operation and reducing sample complexity. Experimental results demonstrate that both WRF-GS and WRF-GS+ outperform baselines for spatial spectrum synthesis, including ray tracing and other deep-learning approaches. Notably, WRF-GS+ achieves state-of-the-art performance in the received signal strength indication (RSSI) and channel state information (CSI) prediction tasks, surpassing existing methods by more than 0.7 dB and 3.36 dB, respectively. The code is available at https://github.com/wenchaozheng/WRF-GSplus.

The upcoming IEEE 802.11be standard, termed WiFi 7, introduces multi-link operation (MLO), enabling devices to establish multiple simultaneous connections utilizing different frequencies and channels. While MLO has the potential to boost network throughput, optimizing channel allocation in WiFi 7 networks introduces many challenges. In this paper, we propose a best-arm identification-enabled Monte Carlo tree search (BAI-MCTS) algorithm for efficient channel allocation in WiFi 7 networks. Specifically, we first employ an efficient mechanism to calculate the network throughput by capturing the essential features of the CSMA protocol. We then formulate this channel allocation problem as a multi-armed bandit (MAB) problem. However, solving this MAB problem induces high sample complexity due to the large-arm space. To overcome this challenge, we introduce BAI-MCTS by combining the BAI and MCTS techniques. Notably, BAI-MCTS has a fast convergence rate and low sample complexity. Simulation results demonstrate that the proposed algorithm outperforms the baseline algorithms in terms of the convergence rate, which is about 42.40% faster than the UCT algorithm when reaching 95% of the optimal value.

WiFi networks have achieved remarkable success in enabling seamless communication and data exchange worldwide. The IEEE 802.11be standard, known as WiFi 7, introduces Multi-Link Operation (MLO), a groundbreaking feature that enables devices to establish multiple simultaneous connections across different bands and channels. While MLO promises substantial improvements in network throughput and latency reduction, it presents significant challenges in channel allocation, particularly in dense network environments. Current research has predominantly focused on performance analysis and throughput optimization within static WiFi 7 network configurations. In contrast, this paper addresses the dynamic channel allocation problem in dense WiFi 7 networks with MLO capabilities. We formulate this challenge as a combinatorial optimization problem, leveraging a novel network performance analysis mechanism. Given the inherent lack of prior network information, we model the problem within a Multi-Armed Bandit (MAB) framework to enable online learning of optimal channel allocations. Our proposed Best-Arm Identification-enabled Monte Carlo Tree Search (BAI-MCTS) algorithm includes rigorous theoretical analysis, providing upper bounds for both sample complexity and error probability. To further reduce sample complexity and enhance generalizability across diverse network scenarios, we put forth LLM-BAI-MCTS, an intelligent algorithm for the dynamic channel allocation problem by integrating the Large Language Model (LLM) into the BAI-MCTS algorithm. Numerical results demonstrate that the BAI-MCTS algorithm achieves a convergence rate approximately 50.44% faster than the state-of-the-art algorithms when reaching 98% of the optimal value. Notably, the convergence rate of the LLM-BAI-MCTS algorithm increases by over 63.32% in dense networks.

Mobile edge cloud (MEC) has emerged as a critical technology for enabling low-latency and real-time mobile device applications. However, an efficient resource allocation framework for improving the user experience in MEC with heterogeneous users is still missing, especially considering the recent sparks of AI-generated content applications. This paper proposes a double-closed-loop online resource allocation (DORA) framework for user experience improvement. This framework employs inner and outer loops to construct the optimal online allocation strategy and recommend a suitable strategy for different types of users, respectively. Based on the DORA framework, we put forth OR2A-HetU, an Online Resource Recommendation and Allocation algorithm for Heterogeneous Users, to solve this resource allocation problem. The OR2A-HetU algorithm proceeds sequentially and can converge to the optimal solution when the time horizon is sufficiently large. The numerical results show that the proposed algorithm outperforms the baseline algorithms, and the user complaint rate decreases from 48.8% to 27.5% when the available resources increase.

The rapid adoption of large language models (LLMs) presents new challenges for existing network architectures due to significant peak traffic and high communication uncertainty. Traditional wireless networks struggle to support efficiently, leading to intolerable response delays, disconnections, and resource wastage. To address these issues, we propose LLM-Slice, the first system to provide dedicated communication slices for LLMs within a wireless network environment. By creating LLM-specific network slices, LLM-Slice efficiently binds services with communication resources. Based on user equipment (UE) requests and a permissions database, the system registers specific slices to offer controllable LLM services, integrating a downlink resource control module to optimize response speed, enhance resource utilization, and reduce disconnections. By deploying and validating in a real UE-gNB-CN environment, numerical results demonstrate that LLM-Slice significantly improves response speed and resource efficiency, providing a novel solution for fast and controllable LLM access in wireless networks.

Location privacy protection (LPP) has become a key concern during mobile crowdsourcing (MCS) task allocation. Existing LPP mechanisms for MCS applications mainly focus on two-dimensional (2D) plane scenarios or directly apply 2D techniques into three-dimensional (3D) space scenarios, leaving the height dimension of 3D geolocation vulnerable to privacy breaches. To facilitate the LPP in 3D MCS, we propose a learning-based geo-perturbation mechanism using 3D geo-indistinguishability (3D-GI). In this mechanism, we first define an optimization objective to balance location privacy and MCS server profit, making it adaptable to different types of MCS applications. Then, we adopt the Asynchronous Advantage Actor-Critic (A3C) algorithm to design a reinforcement learning (RL)-based approach without knowing the accurate system and attack models. This approach enables us to derive the optimal perturbation policy in continuous policy space and accelerates the learning speed using asynchronous multi-thread training. Simulation results demonstrate that the proposed mechanism can better balance location privacy and server profit in 3D MCS applications compared to existing benchmarks.

Federated learning (FL) is an appealing paradigm for learning a global model among distributed clients while preserving data privacy. Driven by the demand for high-quality user experiences, evaluating the well-trained global model after the FL process is crucial. In this paper, we propose a closed-loop model analytics framework that allows for effective evaluation of the trained global model using clients' local data. To address the challenges posed by system and data heterogeneities in the FL process, we study agoal-directedclient selection problem based on the model analytics framework by selecting a subset of clients for the model training. This problem is formulated as a stochastic multi-armed bandit (SMAB) problem. We first put forth a quick initial upper confidence bound (Quick-Init UCB) algorithm to solve this SMAB problem under the federated analytics (FA) framework. Then, we further propose a belief propagation-based UCB (BP-UCB) algorithm under the democratized analytics (DA) framework. Moreover, we derive two regret upper bounds for the proposed algorithms, which increase logarithmically over the time horizon. The numerical results demonstrate that the proposed algorithms achieve nearly optimal performance, with a gap of less than 1.44% and 3.12% under the FA and DA frameworks, respectively.

Restless multi-armed bandits (RMABs) have been widely utilized to address resource allocation problems with Markov reward processes (MRPs). Existing works often assume that the dynamics of MRPs are known prior, which makes the RMAB problem solvable from an optimization perspective. Nevertheless, an efficient learning-based solution for RMABs with unknown system dynamics remains an open problem. In this paper, we fill this gap by investigating a cooperative resource allocation problem with unknown system dynamics of MRPs. This problem can be modeled as a multi-agent online RMAB problem, where multiple agents collaboratively learn the system dynamics while maximizing their accumulated rewards. We devise a federated online RMAB framework to mitigate the communication overhead and data privacy issue by adopting the federated learning paradigm. Based on this framework, we put forth a Federated Thompson Sampling-enabled Whittle Index (FedTSWI) algorithm to solve this multi-agent online RMAB problem. The FedTSWI algorithm enjoys a high communication and computation efficiency, and a privacy guarantee. Moreover, we derive a regret upper bound for the FedTSWI algorithm. Finally, we demonstrate the effectiveness of the proposed algorithm on the case of online multi-user multi-channel access. Numerical results show that the proposed algorithm achieves a fast convergence rate of$\mathcal {O}(\sqrt{T\log (T)})$and better performance compared with baselines. More importantly, its sample complexity reduces sublinearly with the number of agents.

As the cloud is pushed to the edge of the network, resource allocation for user experience improvement in mobile edge clouds (MEC) is increasingly important and faces multiple challenges. This paper studies quality of experience (QoE)-oriented resource allocation in MEC while considering user diversity, limited resources, and the complex relationship between allocated resources and user experience. We introduce a closed-loop online resource allocation (CORA) framework to tackle this problem. It learns the objective function of resource allocation from the historical dataset and updates the learned model using the online testing results. Due to the learned objective model is typically non-convex and challenging to solve in real-time, we leverage the Lyapunov optimization to decouple the long-term average constraint and apply the prime-dual method to solve this decoupled resource allocation problem. Thereafter, we put forth a data-driven optimal online queue resource allocation (OOQRA) algorithm and a data-driven robust OQRA (ROQRA) algorithm for homogenous and heterogeneous user cases, respectively. Moreover, we provide a rigorous convergence analysis for the OOQRA algorithm. We conduct extensive experiments to evaluate the proposed algorithms using the synthesis and YouTube datasets. Numerical results validate the theoretical analysis and demonstrate that the user complaint rate is reduced by up to 100% and 18% in the synthesis and YouTube datasets, respectively.

Due to the harsh propagation environment, limited bandwidth, and constrained battery life, transmission efficiency is a crucial issue for underwater acoustic (UWA) communications. This paper studies the link adaptation problem of a single UWA link by jointly selecting the transmission frequency and data rate. Since the current UWA channel lacks a universal model, we formulate this joint selection problem as a model-based stochastic multi-armed bandit (SMAB) problem. Thereafter, we propose three algorithms to solve this model-based SMAB problem under the settings of the stationary channel, non-stationary channel, and large arm (i.e., frequency and rate pair) space. For the stationary channel, we propose a unimodal objective-based Thompson sampling (UO-TS) algorithm by exploiting the unimodal feature of the objective function. For the non-stationary channel, we put forth a hybrid change detection UO-TS (HCD-UO-TS) algorithm based on the features of the unimodal objective function and non-stationary channel. For the large arm space, we propose an iterative boundary-shrinking TS (IBS-TS) algorithm by using the logistic regression-based arm classification model. These algorithms are all model-based and have low complexity and a fast convergence rate. In addition, we derive an upper regret bound for the UO-TS algorithm. Numerical results show that the proposed algorithms outperform the state-of-the-art bandit algorithms and are not sensitive to the arm space.

This paper considers a mobile edge cloud (MEC) system where several distributed users collaboratively learn a global model by exploiting the over-the-air computing (AirComp) aided federated learning (FL) mechanism. Previous works focus on the FL training process, ignoring the generalization ability of the trained global model. To overcome this, we propose a novel AirComp-aided FL and federated analytics (FL&FA) framework to improve the generalization ability by making full use of user data and opinions. We first formulate this problem as an online user selection problem. Then, we further model it as a stochastic multi-armed bandit (SMAB) framework, where arms are the decentralized users and rewards are user opinions in FA. To tackle the decentralized feature among users, we put forth a belief propagation-based upper confidence bound (BP-UCB) algorithm to solve this SMAB problem. In addition, we derive an upper regret bound for the BP-UCB algorithm, which increases logarithmically over time. Simulation results demonstrate that the proposed algorithm is close to the optimal solution by less than 3.0% and has a fast convergence rate among existing methods.

This paper considers a resource allocation problem where several Internet-of-Things (IoT) devices send data to a base station (BS) with or without the help of the reconfigurable intelligent surface (RIS) assisted cellular network. The objective is to maximize the sum rate of all IoT devices by finding the optimal RIS and spreading factor (SF) for each device. Since these IoT devices lack prior information of the RISs or the channel state information (CSI), a distributed resource allocation framework with low complexity and learning features is required to achieve this goal. Therefore, we model this problem as a two-stage multi-player multi-armed bandit (MPMAB) framework to learn the optimal RIS and SF sequentially. Then, we put forth an exploration and exploitation boosting (E2Boost) algorithm to solve this two-stage MPMAB problem by combining the$\epsilon $-greedy algorithm, Thompson sampling (TS) algorithm, and non-cooperation game method. We derive an upper regret bound for the proposed algorithm, i.e.,$\mathcal {O}(\log ^{1+\delta }_{2} T)$, increasing logarithmically with the time horizon$T$. Numerical results show that the E2Boost algorithm has the best performance among the existing methods and exhibits a fast convergence rate. More importantly, the proposed algorithm is not sensitive to the number of combinations of the RISs and SFs thanks to the two-stage allocation mechanism, which can benefit the high-density networks.

Age-of-information (AoI) based minimization problems have been widely considered in Internet-of-Things (IoT) networks with the settings of multi-source single-channel systems and multi-source multi-channel systems. Most existing works are limited to either the case of identical multi-channel or independent sources. In this paper, we study this problem under the identical and non-identical multi-channel, as well as the correlated sources setting. This correlation defines the case when updating a source’s AoI; others correlated to this one will also reveal partial information. To tackle this AoI-based minimization problem, we formulate it as a correlated restless multi-armed bandit (CRMAB) problem. By decoupling the CRMAB problem into$N$independent single-armed bandit problems, we derive the closed-form expressions of the generalized Whittle index (GWI) and the generalized partial Whittle index (GPWI) under the identical channel and the non-identical channel settings, respectively. Then, we put forth the GWI-based and GPWI-based scheduling policies to solve this AoI-based minimization problem. In addition, we provide two lower numerical performance bounds for the proposed policies by solving the relaxed Lagrange problem of the decoupled CRMAB. Numerical results show that the proposed policies can achieve these lower bounds and outperform the state-of-the-art scheduling policies. Compared with the case of independent sources, the performance of the proposed policies in the case of correlated sources improves significantly, especially in high-density networks.

This article studies the network-level throughput of a full-duplex (FD)-enabled CSMA network, considering the link's transmit power (TP) control, carrier-sensing threshold (CST) adjustment, and logarithm access intensity (LAI) adaptation. With the FD technique, a transmitter-receiver pair can transmit and receive simultaneously in the same frequency band. We aim to find the best combination of TP, CST, and LAI for each link to maximize the FD-CSMA network throughput. However, adjusting each link's TP and CST will change the network's carrier-sensing relation or contention graph, consequently leading to a computationally intractable network optimization problem. On the other hand, it is difficult to jointly optimize these three parameters in a fully distributed network. To overcome these, we first decompose this network optimization problem into two subproblems: 1) a joint control and scheduling problem in the transport- and media access control (MAC)-layer and 2) a parameter selection problem in the PHY-layer. Then, the multiplayer multiarmed bandit (MPMAB) framework has been introduced to address this problem by solving the two subproblems alternately. We put forth a fully distributed algorithm, named the stochastic and adversarial optimal FD-CSMA (SAO-FD-CSMA) algorithm, to solve the MPMAB problem by taking advantage of the optimization tool and the bandit theory. The numerical results show that the proposed algorithm outperforms the state-of-the-art bandit algorithms and can improve the network throughput by 43% compared with the random selection method.

Due to limited acoustic bandwidth and constrained battery life, transmission efficiency is a crucial issue in underwater acoustic communication (UAC). This paper studies the problem of joint frequency and transmission rate selection of a single link in UAC so as to maximize the link's average throughput. To handle this problem, we first describe this problem as a traditional optimization form and show the challenges located in solving it. Then we resort to the online learning theory by modeling this problem as a multi-armed bandit (MAB) framework. Through taking full advantage of the unimodality feature of the problem structure, we propose an algorithm called UOTS (unimodal objective based Thompson sampling algorithm) to solve this MAB problem. A finite-time analysis of the upper regret bound has been derived for the proposed algorithm. Several numerical results are also provided to verify the proposed algorithm and demonstrate that UOTS outperforms the current state-of-the-art algorithms. It is interesting that the performance loss of UOTS does not depend on the number of available pairs of frequency and rate, which can be much useful in the practical implementation.

This paper investigates the network-level throughput of a full-duplex (FD) enabled CSMA network, considering transmit power (TP) control and carrier-sensing threshold (CST) adjustment. With the FD technique, a transmitter-receiver pair can transmit and receive simultaneously in the same frequency band. The motivation is to find an optimal combination of TP and CST for each link so as to maximize the network throughput. The challenge is that adjusting each link's TP and CST will change the network's carrier-sensing relation and interference relation, which consequently leads to a computationally intractable network optimization problem. To overcome the complexity challenge, we model this network throughput maximum problem within a multi-player multi-armed bandit (MP-MAB) framework, in which the players are the FD-enabled links and the arms are the combinations of TP and CST. The proposed framework can also be viewed as an adversarial MP-MAB due to the hostile contention among links. Furthermore, we propose a refined Exponential-weight algorithm for Exploration and Exploitation (Exp3) to solve this adversarial MP-MAB problem. The refined Exp3 algorithm proceeds in epochs and starts with some prior knowledge. The numerical results show that the proposed method can improve the network throughput by more than 42%, compared with the random selection method. Meanwhile, the proposed algorithm exhibits a fast convergence rate in random network scenario.

Cooperative spectrum sensing has been studied to combat the hidden terminal problem by exploiting the spatial diversity in cognitive radio (CR) networks. This paper concerns blind cooperative spectrum sensing with soft fusion, where thea prioriknowledge of channels and primary signals is unavailable, and soft information is transmitted from each secondary user (SU) to a fusion center for detection. We first introduce the Quade test to design a blind detector. Then, a new detector with both lower computational complexity and lower overhead is derived, where only the estimated power and the variance of the instantaneous power at each SU are required at the fusion center. The analytical expressions for the detection performance, in terms of false-alarm probability and detection probability, are derived for the proposed detector. Simulation results are provided to validate the theoretical analyses and demonstrate the superior performance of proposed detector compared to the state-of-the-art detectors. It is also shown that, with the increase of the number of hidden terminals in the CR, the proposed detector can maintain high detection performance while the conventional detectors exhibit rapid performance degradation.