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Cooperative spectrum sensing in cognitive radio systems with limited sensing ability
Hui HUANG, Zhao-yang ZHANG, Peng CHENG, Ai-ping HUANG, Pei-liang QIU
Front. Inform. Technol. Electron. Eng., 2010, 11(3): 175-186.
https://doi.org/10.1631/jzus.C0910027
In cognitive radio systems, the design of spectrum sensing has to face the challenges of radio sensitivity and wide-band frequency agility. It is difficult for a single cognitive user to achieve timely and accurate wide-band spectrum sensing because of hardware limitations. However, cooperation among cognitive users may provide a way to do so. In this paper, we consider such a cooperative wide-band spectrum sensing problem with each of the cognitive users able to imperfectly sense only a small portion of spectrum at a time. The goal is to maximize the average throughput of the cognitive network, given the primary network’s collision probability thresholds in each spectrum sub-band. The solution answers the essential questions: to what extent should each cognitive user cooperate with others and which part of the spectrum should the user choose to sense? An exhaustive search is used to find the optimal solution and a heuristic cooperative sensing algorithm is proposed to simplify the computational complexity. Inspired by this optimization problem, two practical cooperative sensing strategies are then presented for the centralized and distributed cognitive network respectively. Simulation results are given to demonstrate the promising performance of our proposed algorithm and strategies.
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Automatic inspection of LED indicators on automobile meters based on a seeded region growing algorithm
Hong ZHOU, Hai-er XU, Pei-qi HE, Zhi-bai SONG, Chen-ge GENG
Front. Inform. Technol. Electron. Eng., 2010, 11(3): 199-205.
https://doi.org/10.1631/jzus.C0910144
Light emitting diode (LED) indicators used on automobile meters are essential for safe driving and few errors can be tolerated. The current manual inspection approach can achieve only 95% accuracy rate in weeding out errors occurring in the production process. It is imperative to improve the accuracy of the inspection process to better achieve the goal of safe driving. This paper proposes an automatic inspection method for LED indicators for use on automobile meters. Firstly, red-green-blue (RGB) color images of LED indicators are acquired and converted into R, G, and B intensity images. A seeded region growing (SRG) algorithm, which selects seeds automatically based on Otsu’s method, is then used to extract the LED indicator regions. Finally, a region matching process based on the seed and three area parameters of each region is applied to inspect the LED indicators one by one to locate any errors. Experiments on standard automobile meters showed that the inspection accuracy rate of this method was up to 99.52% and the inspection speed was faster compared with the manual method. Thus, the new method shows good prospects for practical application.
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A secure threshold Paillier proxy signature scheme
Pei-yih TING, Xiao-wei HUANG, Jun-hui WU, Chia-huei HSEU
Front. Inform. Technol. Electron. Eng., 2010, 11(3): 206-213.
https://doi.org/10.1631/jzus.C0910493
As e-commerce applications and the underlying public key infrastructure have become more popular over time, many digital mechanisms emulating traditional business activities have been developed and deployed. To build a full-fledged secure digital world, secure implementations of more commercial activity primitives are required. In this paper, we present a secure proxy signature scheme and its threshold version based on the homomorphic Paillier cryptosystem, which can be used in many e-commerce applications such as e-voting, e-bidding/auction, and privacy-preserving data mining. These two schemes are existentially unforgeable against chosen-message attacks and chosen-warrant attacks in the random oracle model. Although it is based on factoring, the threshold Paillier proxy scheme operates without requiring any trusted dealer or combiner. Thus, these two schemes are practical for integration in modularized secure multi-party protocols.
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7 articles
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