Uncrewed aerial vehicles (UAVs) ad-hoc network is expected to play an important role in the integrated sensing and communication (ISAC) due to its flexible topology and low cost, enabling scalable connectivity. However, the Line of Sight and node mobility of UAVs lead to severe wireless interference and highly dynamic network topology, making the design of distributed medium access control protocols for large-scale UAV ad-hoc network a critical problem. Here, we propose H-SATMAC, a hybrid self-adaptive time-division multiple access-based MAC protocol for large-scale UAV ad-hoc networks. In order to jointly consider the transmission of the periodic and aperiodic packets, we design a hybrid channel resource scheduling method based on time slot groups. The consecutive free time slots in the group are used as the contention window for CSMA-based transmissions. We utilize a dynamic mapping of slot groups and the geohash coding system to avoid hidden terminal problem and load-balance multiple group resources. Besides, an enhanced time slot adjustment and adaptive frame length method is designed to achieve better channel utilization while avoiding channel collisions between nodes. We conduct theoretical analysis and extensive simulations to evaluate H-SATMAC. Simulation results show that H-SATMAC achieves 22% higher channel utilization and above 64% larger number of total reception packets than that of the reference protocol.

Recently, deep learning for hyperspectral image classification has been successfully applied, and some convolutional neural network (CNN)-based models already achieved attractive classification results. Since hyperspectral data is a spectral-spatial cube data that can generally be considered as sequential data along with the spectral dimension, CNN models perform poorly on such a sequential data. Unlike convolutional neural networks (CNNs) that mainly concern with local relationship models in images, transformer has been shown to be a powerful structure for qualifying sequential data. In the SA (self-attention) module of ViT, each token is updated through aggregating all token’s features based on the self-attention graph. Through this, tokens can exchange information sufficiently among each other which provides a powerful representation capability. However, as the layers become deeper, the transformer model suffers from network degradation. Therefore, in order to improve the layer-to-layer information exchange and alleviate the network degradation problem, we propose a Weighted Residual Self-attention Graph-based Transformer (RSAGformer) model for hyperspectral image classification with respect to the self-attention mechanism. It effectively solves the network degradation problem of deep transformer model by fusing the self-attention information between adjacent layers and extracts the information of data effectively. Extensive experiment evaluation with six public hyperspectral datasets shows that the RSAGformer yields competitive results for classification.

The integrity of real-time data streams has not been solved for a long time and has gradually become a difficult problem in the field of data security. Most of the current data integrity verification schemes are constructed using cryptographic algorithms with complex computation, which cannot be directly applied to real-time stream computing systems. Aiming at the above issue, this paper adopts the Carter–Wegman MAC method, pseudo-random function and symmetric cryptography mechanism to construct the Real-Time Data Integrity Verification scheme based on symmetric key in stream computing systems (RT-DIV), which converts a one-time MAC to a multiple-time MAC and retains the advantage of security performance. Then, a security analysis is given under the standard model. Finally, experiments and data analysis are conducted in a simulated environment, and the experimental results show that the RT-DIV scheme can effectively guarantee the integrity of real-time data streams. Furthermore, the RT-DIV scheme lays the foundation for the secure application of the stream computing system.

Data integrity is a prerequisite for ensuring data availability of IoT data and has received extensive attention in the field of IoT big data security. Stream computing systems are widely used in the field of IoT for real-time data acquisition and computing. However, the real-time, volatility, suddenness, and disorder of stream data make data integrity verification difficult. According to the survey, there is no mature and universal solution. To solve this issue, we constructed a data integrity verification algorithm scheme of the stream computing system (S-DIV) by utilizing homomorphic message authentication code and pseudo-random function security assumption. Furthermore, based on S-DIV, an external data integrity tracking and verification system is constructed to track and analyze the message data stream in real time. By verifying the data integrity of message during the whole life cycle, the problem of data corruption or data loss can be found in time, and error alarm and message recovery can be actively implemented. Then, we conduct the formal security analysis under the standard model and, finally, implement the S-DIV scheme in simulation environment. Experimental results show that the scheme can guarantee data integrity in an acceptable time without affecting the efficiency of the original system.