In this paper, we propose a novel cooperative roadside unit (RSU) broadcast approach that can effectively enhance the vehicles’ packet-reception rates of the messages broadcast cooperatively by nearby RSUs. To enable message-aggregation among RSUs, we propose a new vehicular-message format based on the software-defined multiplexing code which can aggregate multiple messages without any need of packet form. To facilitate our proposed new cooperative scheme, RSUs must be organized into clusters. We formulate this RSU clustering problem as a graph partitioning problem, which aims to make individual cluster sizes as close to each other as possible. Furthermore, we design a new heuristic algorithm to efficiently solve this problem. This heuristic algorithm is also compared with the random clustering and minimum-degree clustering schemes in terms of the modified Gini index. The theoretical analysis of our proposed cooperative RSU broadcast scheme is also conducted to guarantee that our proposed new cooperative RSU-broadcast approach can improve the packet reception rate. Furthermore, we simulate the vehicular environment with the simulation tools SUMO and NS-3 as benchmarks. The simulation demonstrates that our proposed new cooperative RSU-broadcast system will increase the packet reception rate and the number of successfully received packets over the conventional non-cooperative broadcast system.

Image mosaic is a prevalent technique to conceal critical content in images. However, conventional mosaic techniques cannot be recovered using a small-sized key, as they require retransmission of the original images for perfect recovery. In this work, we propose a novel, computationally efficient, and effective recoverable image-mosaic technique. A key advantage of our proposed image-mosaic scheme is its robust performance across a range of adjustable key lengths. Our technique effectively conceals original information even with a small-sized key of only a few bits. To evaluate its performance, we introduce a new image-similarity metric based on the magnitude of the discrete cosine transform (DCT). This metric exhibits several advantageous mathematical properties, including the ability to quantify the perceptibility of major content in mosaicked images, invariance under image reflections and 180-degree rotations, and insensitivity to small translations. Finally, numerical experiments demonstrate that our method outperforms existing recoverable image-mosaic techniques and performs consistent across varying key lengths. We also compare the run-times required by our proposed new scheme with those required by other existing recoverable image-mosaic methods and the state-of-the-art image-encryption methods to exhibit the computational efficiency of our proposed new scheme.