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An Efficient Routing in Urban Vehicular Ad Hoc Networks
Xu Liya,Deng Anyuan,Gao Guangyong,Yang Wenzhong,Cheng Yong 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.8
VANET is a highly mobile wireless ad hoc network that is targeted to support road safety, traffic monitoring and other applications. The node communication is easy to break due to the high mobility of vehicles and the road layout. In this paper, we propose an efficient routing based on static node assistance. The static nodes are fixed in each intersection. Each static node stores information of other static nodes in path. The routing takes static nodes as backbone nodes and vehicles as relay nodes between static nodes. The static nodes are selected dynamically and sequentially, and they are chosen according to the delay that packets are forwarded from the current static node to the candidate one. The vehicular relay selection between two static nodes considers the link stability as the parameter. Simulation results show performance improvement comparing with performance of other existing routing approaches.
Reversible Watermarking with Adaptive Embedding Threshold Matrix
( Guangyong Gao ),( Yun-qing Shi ),( Xingming Sun ),( Caixue Zhou ),( Zongmin Cui ),( Liya Xu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.9
In this paper, a new reversible watermarking algorithm with adaptive embedding threshold matrix is proposed. Firstly, to avoid the overflow and underflow, two flexible thresholds, TL and TR, are applied to preprocess the image histogram with least histogram shift cost. Secondly, for achieving an optimal or near optimal tradeoff between the embedding capacity and imperceptibility, the embedding threshold matrix, composed of the embedding thresholds of all blocks, is determined adaptively by the combination between the composite chaos and the average energy of Integer Wavelet Transform (IWT) block. As a non-liner system with good randomness, the composite chaos is suitable to search the optimal embedding thresholds. Meanwhile, the average energy of IWT block is calculated to adjust the block embedding capacity, and more data are embedded into those IWT blocks with larger average energy. The experimental results demonstrate that compared with the state-of-the-art reversible watermarking schemes, the proposed scheme has better performance for the tradeoff between the embedding capacity and imperceptibility.