Radio simultaneously localization and mapping (SLAM) is indispensable for a wide range of wireless applications owing to its ability to provide both location and mapping information. Traditional radio SLAM systems use fixed-aperture antennas with invariant beamwidths, which cannot adapt to the varying requirements for beam gain and coverage in complex environments. In this paper, we propose an aperture-changeable reconfigurable holographic surface (RHS)-assisted SLAM system. By deactivating different numbers of RHS elements, the equivalent antenna aperture is changeable, leading to adaptive beamwidths across detection directions. However, the RHS should follow the leakage power constraint, which stipulates that the total radiated power of RHS elements cannot exceed the input power. Its impact on the elements’ radiated power makes the optimization of RHS equivalent aperture challenging. To address this issue, we formulate a detection probability maximization problem and then adopt a two-step decomposition method to solve it. In the first step, we relax the leakage power constraint to obtain a relaxed solution. In the second step, we refine the relaxed solution by incorporating the leakage power constraint. We analyze the impact of RHS equivalent aperture and leakage power constraint on the SLAM system and evaluate the complexity of the proposed algorithm. Simulation results demonstrate that the proposed SLAM system can effectively reduce agent localization error compared with benchmark schemes.

Long-term time series forecasting (LTSF) seeks to make accurate long-term predictions by leveraging extensive historical data, which is crucial for solving scientific and engineering challenges. Traditional transformer-based methods process historical segments individually, leading to a limited view that overlooks distant dependencies within the entire time series. In this paper, we introduce the Segment-Recurrent Transformer (SRTrans), designed to provide a more comprehensive understanding of historical time series dynamics. By incorporating segment-level recurrence into the Transformer, our model enhances inter-segment information flow, capturing longer-term and global dependencies. We also propose a multi-scale adaptive fusion module that efficiently integrates diverse patterns using a variable-scale chunking mechanism and a weight-mixing strategy. Additionally, our spectrum purge operation improves data preprocessing by extracting significant long-term patterns from the frequency domain. Extensive experiments on eight real-world datasets demonstrate SRTrans’s effectiveness in accuracy and efficiency, offering a promising new solution for LTSF tasks.

Transformer with self-attention was initially crafted to model language sequences, where discrete tokens (i.e., words) showcase high semantic density. However, when applied to time series token inputs (i.e., datapoints) with weak-density semantics and temporal redundancy, it faces challenges as these time-domain tokens impede its ability to capture the intricate latent properties of time series dynamics. While time-frequency transformation presents a viable solution by bringing forth a new space with heightened expressive power, existing approaches fall short of fully exploiting its potential. In response to these limitations, we propose a general-purpose transformer-based model, named Scattering Transformer, for multivariate time series forecasting and self-supervised representation learning. It is based on two innovative components: i) scattering self-attention mechanism incorporating wavelet key/value and standard query to unify the learning of cross-domain relationships between the time and wavelet domains; and ii) stochastic scaling positional encoding scheme that relies solely on order information, emulating longer sequence positions to generalize up to ultra-long horizon case. Extensive experiments on eight real-world benchmarks show the potential of our Scattering Transformer as a robust and versatile solution, showcasing its quadruple efficacy of non-stationary forecasting, ultra-long horizons forecasting, representation learning, and reduction in time and space complexity.

As a crucial facilitator of future autonomous driving applications, wireless simultaneous localization and mapping (SLAM) has drawn growing attention recently. However, the accuracy of existing wireless SLAM schemes is limited because the antenna gain is constrained given the cost budget due to the expensive hardware components such as phase arrays. To address this issue, we propose a reconfigurable holographic surface (RHS)-aided SLAM system in this paper. The RHS is a novel type of low-cost antenna that can cut down the hardware cost by replacing phased arrays in conventional SLAM systems. However, compared with a phased array where the phase shifts of parallel-fed signals are adjusted, the RHS exhibits a different radiation model because its amplitude-controlled radiation elements are series-fed by surface waves, implying that traditional schemes cannot be applied directly. To address this challenge, we propose an RHS-aided beam steering method for sensing the surrounding environment and design the corresponding SLAM algorithm. Simulation results show that the proposed scheme can achieve more than there times the localization accuracy that traditional wireless SLAM with the same cost achieves.

Received signal strength (RSS) fingerprint map is one of the most widely-used indoor localization approaches, but it often relies on multiple access points (AP) for data collection and suffers from frequent data updates due to dynamic wireless environments. In this work, we implement a reconfigurable-intelligent-surface (RIS) assisted indoor localization system named Meta2Locate to tackle the above issues using only one AP. In the proposed system, we deploy our self-designed RIS at 5.5GHz in an indoor environment, which can customize the propagation channels between the AP and the target. For the changing propagation environment, we design a mean maximum discrepancy weighted meta-learning approach to train a model that maps the RSS fingerprint to the location of the user, and it only needs a few data for the model update.

Edge computing has been viewed as a powerful technology to realize the vision of network services. However, due to the limited capabilities and insufficient security systems, edge computing is vulnerable to distributed denial of service (DDoS) attacks which may exhaust the resources of edge servers with excessive requests and degrade their service capabilities. Setting detection thresholds for DDoS detection indicators can effectively prevent DDoS attacks, but existing thresholding methods fail to update detection thresholds in time to guarantee the detection performance whenever the system settings vary. In this paper, we propose a multi-dimensional thresholding method against DDoS attacks in edge computing. We design three detection indicators based on the behavior features of DDoS attackers. By solving a threshold optimization problem, we obtain closed-form solutions and numerical solutions of the optimal detection thresholds, which adapt to dynamic system settings. Simulations show that the proposed thresholding method has a superior detection performance in terms of both the accuracy and robustness.

Wireless simultaneous localization and mapping (SLAM) has attracted much attention as a promising technique to empower location based services. However, the accuracy of traditional wireless SLAM systems is limited as the wireless signals are easily disturbed by the uncontrollable radio environments. To mitigate this issue, in this paper, we propose a MetaSLAM system where multiple reconfigurable intelligent surfaces (RISs) are deployed to customize the wireless environments. To be specific, through adjusting the phase shifts of these RISs, the strength of reflected signals can be enhanced in order to resist the variance of radio environments. However, it is challenging to coordinate multiple RISs and optimize their phase shifts especially when their locations are unknown to the agent. In order to address these challenges, we formulate a MetaSLAM optimization problem, and design a two-stage optimization algorithm based on the genetic and particle filter algorithms to solve the formulated problem. Analysis of the complexity and the positioning error bound of the proposed SLAM system are provided. Simulation results show that compared with the benchmark schemes, the positioning error obtained by the MetaSLAM system is reduced by at least 31%.

Multi-label image classification (MLIC) is a more challenging task compared with single-label image classification due to multiple concepts targets, and complex visual relationships should be formulated. Convolutional Neural Network (CNN) and Visual Transformer (ViT) have shown superior performance in local and global feature representations, respectively. However, the interactions between local and global features are neglected in current works. To further formulate the critical interactions, this paper designs a Unified Feature Interaction (UFI) framework, aiming to integrate the selected local features with global features based on CNN and ViT, simultaneously. The proposed UFI includes two key modules: Class-Related Feature Selection (CRFS) and Feature Interaction Attention (FIA) modules. Specifically, according to the activation map, CRFS selects target regions by the preliminary calculation of predicted scores. FIA enables the significant local-global feature interaction based on the selected target regions and whole image. We initially attempted to interact with local and global features for multi-label image classification. UFI provides a stable improvement over the baseline and produces a new state-of-the-art result on MS-COCO and VOC2007.

Indoor wireless simultaneous localization and mapping (SLAM) is considered as a promising technique to provide positioning services in future 6G systems. However, the accuracy of traditional wireless SLAM system heavily relies on the quality of propagation paths, which is limited by the uncontrollable wireless environment. In this paper, we propose a novel SLAM system assisted by a reconfigurable intelligent surface (RIS) to address this issue. By configuring the phase shifts of the RIS, the strength of received signals can be enhanced to resist the disturbance of noise. However, the selection of phase shifts heavily influences the localization and mapping phase, which makes the design very challenging. To tackle this challenge, we formulate the RIS-assisted indoor SLAM optimization problem and design an error minimization algorithm for it. Simulations show that the RIS assisted SLAM system can decrease the positioning error by at least 31% compared with benchmark schemes.