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In this paper, we propose a novel DWT-based fragile watermarking scheme by exploiting the characteristics of the human visual system (HVS). Multi-resolution tamper detection and image fusion are applied to watermark detection and accurate tamper region location. To distinguish between incidental and malicious modifications, some effective rules are presented. Mathematical morphology operations are...
The nickel ore slurry sloshing in a rolling partially loaded prismatic cargo hold with a longitudinal baffle is investigated. A numerical model based on the volume of fluid (VOF) method and the non-Newtonian Herschel-Bulkley and Bingham equations is proposed to study the dynamic behavior of nickel ore slurry sloshing. The numerical model is solved by using the finite volume approximations and the...
In this paper, we consider the buffer-aided multi-relay MIMO-OFDM networks and propose a joint space-time-frequency subchannel pairing scheme, in which subchannels of the source to relay links and relay to the destination links are paired in time, frequency, and space domain (TPFPSP) simultaneously. TPFPSP scheme can increase the equivalent channel gains between source and destination. We derive new...
Energy-efficiency, high data rates and secure communications are essential requirements of the future wireless networks. In this paper, we develop a framework to study the energy efficiency for enhancing physical layer security (PLS) in large-scale random cognitive radio networks (CRNs) considering the node spatial distribution, wireless propagation medium and aggregate network interference. Using...
We analyze the impact of channel estimation errors on amplify-and-forward (AF) cooperative communication systems over Nakagami-m fading channels. We derive exact closed-form expression of the average symbol error rate (SER) with channel estimation errors by using the moment-generating function (MGF) based approach. Numerical results confirm that our theoretical analysis is very accurate.
In this paper, we analyze the performance of single relay selection cooperative wireless networks using decode-and-forward relaying. Under optimum relay selection, the expressions for asymptotic outage probability, average symbol error probability are derived over Nakagami-m fading channels. Then we improve the performance of the system through optimum power allocation based on asymptotic outage probability...
The hybrid auto repeat request (HARQ) is an efficient retransmission technique which can guarantee highly reliable communication over noisy channels, and nowadays it has been widely adopted in packet-based data communication systems. In this paper, we propose an improved Type-II Hybrid-ARQ scheme that can degrade the average number of the iteration and improve the performance. In this scheme, the...
More than an adaptive system, the cognitive radio system should be a kind of intelligent system. In the paper, a Q-learning algorithm of the intelligent control theory is adopted to solve the sensing task selection problem among cognitive radio users in the distributed cognitive radio networks. In the proposed scheme, each cognitive radio user selects its sensing task through times of interaction...
We consider the channel estimation for two-way relay OFDM networks. We proposed an LS-based channel estimation algorithm under block-based training schemes. Based on the mean square error (MSE) criterion, the condition and the design method for optimal training sequences are discussed. To reduce peak-to-average power ratio (PAPR), a special sequence called Zadoff-Chu sequence is employed to design...
In the traditional schemes, the collided packets will be discarded and retransmitted, which results in depression of performance and waste of energy. The packets collision resolution (PCR) schemes based on virtual-MIMO techniques could resolve collision by selecting cooperative nodes to form virtual parallel channels and hence can deal with the collisions easily. In this article, we analyze the performance...
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