Implementing federated learning (FL) over wireless networks faces critical research challenges, such as high communication costs, inevitable communication latency, and significant energy consumption for model transmission and training, primarily caused by device heterogeneity and unpredictable dynamic channel conditions. This paper proposes Graph-based Resource Optimization with Compression for FL (GROC-FL), a unified framework that jointly coordinates wireless resource allocation and collaborative model compression. By leveraging Graph Neural Networks (GNNs) to model wireless topology and Deep Reinforcement Learning (DRL) to optimize communication and computation resources together with a globally consistent sparse update mechanism, GROC-FL minimizes the overall energy consumption of clients over wireless networks. In order to address the intrinsic topology dependence of wireless FL, we develop a graph-augmented DRL agent based on a graph convolutional network (GCN) that captures resource competition and network topology. We further develop a collaborative model compression module, termed Federated Parameter Negotiation (FPN), which enables clients to negotiate a global sparse mask and further reduce energy consumption during FL training. Experimental results demonstrate that GROC-FL outperforms the baselines in energy consumption, training performance, and client fairness.

In this paper, we propose a hybrid simultaneous wireless information and power transfer (SWIPT)–enabled multiple-input multiple-output (MIMO) architecture, where the base station (BS) uses a conventional radio-frequency (RF) transmitter for downlink transmission and a Rydberg atomic quantum receiver (RAQR) for receiving uplink signals from Internet of Things (IoT) devices. To fully exploit this integration, we jointly design the transmission scheme and the power-splitting strategy to maximize the weighted sum rate, which leads to a non-convex problem. To address this challenge, we first derive closed-form lower bounds on the uplink achievable rates for maximum ratio combining (MRC) and zero-forcing (ZF), as well as on the downlink rate and harvested energy for maximum ratio transmission (MRT) and ZF precoding. Building upon these bounds, we propose an iterative algorithm relying on the best monomial approximation and geometric programming (GP) to solve the non-convex problem. Finally, simulations validate the tightness of our derived lower bounds and demonstrate the superiority of the proposed algorithm over benchmark schemes. Importantly, by integrating RAQR with SWIPT-enabled MIMO, the BS can reliably detect weak uplink signals from IoT devices powered only by harvested energy, enabling battery-free IoT networks.

In this paper, we investigate a cell-free massive multiple-input and multiple-output (MIMO)-enabled integration communication, computation, and sensing (ICCS) system, aiming to minimize the maximum overall latency to guarantee the stringent sensing requirements. We consider a two-tier offloading framework, where each multi-antenna terminal can optionally offload its local tasks to either multiple mobile-edge servers for distributed computation or the cloud server for centralized computation. The above offloading problem is formulated as a mixed-integer programming and non-convex problem, which can be decomposed into three sub-problems, namely, distributed offloading decision, beamforming design, and execution scheduling mechanism. First, the continuous relaxation and penalty-based techniques are applied to tackle the distributed offloading strategy. Then, the weighted minimum mean square error (WMMSE) and successive convex approximation (SCA)-based lower bound are utilized to design the integrated communication and sensing (ISAC) beamforming. Finally, the other resources can be judiciously scheduled to minimize the maximum latency. A rigorous convergence analysis and numerical results substantiate the effectiveness of our method. Furthermore, simulation results demonstrate the benefits of multi-point cooperation in cell-free massive MIMO-enabled ICCS and reveal the trade-off between the number of involved APs and the resulting latency, highlighting the inherent interplay among communication, sensing, and computation.

As a fundamental task for intelligent robots, visual SLAM has made significant progress in recent years. However, robust SLAM in weakly textured environments remains a challenging task. In this paper, we present a novel visual Robust SLAM for Weak-Textured environments (RWT-SLAM) to address this problem. Unlike existing methods that use detector-based deep networks for interest point detection, we propose extracting distinctive features from a detector-free based network, namely LoFTR, to avoid the difficulty of manual annotations of feature points in weakly textured images. We generate multi-level feature vectors from LoFTR to form dense descriptors for each pixel in the input image. A keypoint localization component is then proposed to measure the saliency of the descriptors and select the distinctive pixels as keypoints. We integrate this new keypoint into the popular ORB-SLAM framework and compare it with the state-of-the-art methods. Extensive experiments on popular TUM RGB-D, OpenLORIS-Scene, as well as our own dataset are carried out. The results demonstrate the superior performance of our method in weakly textured environments.

In this paper, to tackle the blockage issue in massive multiple-input-multiple-output (mMIMO) systems, a reconfigurable intelligent surface (RIS) is seamlessly deployed to support devices with ultra-reliable and low-latency communications (URLLC). The transmission power of the base station and the phase shifts of the RIS are jointly devised to maximize the weighted sum rate while considering the spatially correlation and channel estimation errors. Firstly, the relationship between the channel estimation error and spatially correlated RIS’s elements is revealed by using the linear minimum mean square error. Secondly, based on the maximum-ratio transmission precoding, a tight lower bound of the rate under short packet transmission is derived. Finally, the NP-hard problem is decomposed into two optimization problems, where the transmission power is obtained by geometric programming and phase shifts are designed by using gradient ascent method. Besides, we have rigorously proved that the proposed algorithm can rapidly converge to a sub-optimal solution with low complexity. Simulation results confirm the tightness between the analytic results and Monte Carlo simulations. Furthermore, the two-timescale scheme provides a practical solution for the short packet transmission.

In this paper, the reconfigurable intelligent surface (RIS)-aided massive multiple-input-multiple-output (mMIMO) system with ultra-reliability and low latency communications (URLLC) is investigated. Specifically, the spatial correlation and imperfect channel estate information (CSI) are considered, where the phase shifts of the RIS and the transmission power of the base station (BS) are jointly optimized to maximize the weighted sum rate. Firstly, the aggregated channel is estimated relying on the linear minimum mean square error (LMMSE) method, and the normalized mean square error (NMSE) is analyzed. Secondly, the lower bound for the achievable data rate is derived for maximum-ratio transmission (MRT). Finally, the non-convex problem is separated into two optimization problems. Then, based on the statistical CSI, geometric programming and gradient descent are adopted to optimize the transmission power of the BS and the phase shifts of the RIS, respectively. Simulation results confirm the accuracy of the analytic results and the superiority of our proposed algorithm.

Resource allocation is conceived for cell-free (CF) massive multi-input multi-output (MIMO)-aided ultra-reliable and low latency communication (URLLC) systems. Specifically, to support multiple devices with limited pilot overhead, pilot reuse among the users is considered, where we formulate a joint pilot length and pilot allocation strategy for maximizing the number of devices admitted. Then, the pilot power and transmit power are jointly optimized while simultaneously satisfying the devices’ decoding error probability, latency, and data rate requirements. Firstly, we derive the lower bounds (LBs) of ergodic data rate under finite channel blocklength (FCBL). Then, we propose a novel pilot assignment algorithm for maximizing the number of devices admitted. Based on the pilot allocation pattern advocated, the weighted sum rate (WSR) is maximized by jointly optimizing the pilot power and payload power. To tackle the resultant NP-hard problem, the original optimization problem is first simplified by sophisticated mathematical transformations, and then approximations are found for transforming the original problems into a series of subproblems in geometric programming (GP) forms that can be readily solved. Simulation results demonstrate that the proposed pilot allocation strategy is capable of significantly increasing the number of admitted devices and the proposed power allocation achieves substantial WSR performance gain.

Smart factories need to support the simultaneous communication of multiple industrial Internet-of-Things (IIoT) devices with ultra-reliability and low-latency communication (URLLC). Meanwhile, short packet transmission for IIoT applications incurs performance loss compared to traditional long packet transmission for human-to-human communications. On the other hand, cell-free massive multiple-input and multiple-output (CF mMIMO) technology can provide uniform services for all devices by deploying distributed access points (APs). In this paper, we adopt CF mMIMO to support URLLC in a smart factory. Specifically, we first derive the lower bound (LB) on achievable uplink data rate under the finite blocklength (FBL) with imperfect channel state information (CSI) for both maximum-ratio combining (MRC) and full-pilot zero-forcing (FZF) decoders. The derived LB rates based on the MRC case have the same trends as the ergodic rate, while LB rates using the FZF decoder tightly match the ergodic rates, which means that resource allocation can be performed based on the LB data rate rather the exact ergodic data rate under FBL. The log-function method and successive convex approximation (SCA) are then used to approximately transform the non-convex weighted sum rate problem into a series of geometric program (GP) problems, and an iterative algorithm is proposed to jointly optimize the pilot and payload power allocation. Simulation results demonstrate that CF mMIMO significantly improves the average weighted sum rate (AWSR) compared to centralized mMIMO. An interesting observation is that increasing the number of devices improves the AWSR for CF mMIMO whilst the AWSR remains relatively constant for centralized mMIMO.