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A new semantic steganographic algorithm for hiding data in the motion trajectories of Video Objects (VOs) is presented. First, a set of primitives (objects bounding-box coordinates and its centroid) are used to dene a VO. The centroid of VO is tracked in each frame and its coordinate is stored in a trajectory vector. The proposed algorithm embeds data in the VO object trajectory by presenting a relationship...
Cognitive Radio (CR) systems have been proposed to enable flexible use of the frequency spectrum in future generations of wireless networks. These are expected to detect spectrum bands that are not actively used by licensed (primary) users and provide unlicensed (secondary) users access to these bands. In this context it is important for the CR systems to promptly react to changes in the operating...
In this paper, a distinctive cyclostationarity-based feature of the Long Term Evolution (LTE) Orthogonal Frequency Division Multiplexing (OFDM) signals used in the Frequency Division Duplex (FDD) downlink transmission is proved, and further employed for their detection. This relates to the existence of the reference signals (RSs) used for channel estimation and cell search/acquisition purposes. The...
In this paper we present a new algorithm for detecting mobile Worldwide Interoperability for Microwave Access (WiMAX) signals in cognitive radio systems, which is based on preamble-induced second-order cyclostationarity. We derive closed form expressions for the cyclic autocorrelation function (CAF) and cyclic frequencies (CFs) due to the preamble, and use these results in the proposed algorithm for...
In this paper we study joint transmitter adaptation and power control in multiuser wireless systems with multipath channels and target values imposed on the users' signal-to-interference+noise-ratio (SINR) at the receiver. We use a general framework that is applicable to a wide range of wireless systems and scenarios to cast this as a distributed constrained optimization problem, and study necessary...
Spectrum awareness is one of the most challenging tasks in cognitive radio (CR). To adequately adapt to the changing radio environment, it is necessary for the CR to be able to perform joint detection and classification of low signal-to-noise ratio (SNR) signals without requiring much a priori information on the signal parameters. In this paper, we propose a joint detection and classification algorithm...
In this paper we consider OFDM-based cognitive radios (CR) with linear precoders at the transmitter and minimum mean square error (MMSE) filters at the receiver, and formulate joint spectral allocation and power control subject to specified target signal-to-interference+noise ratio (SINR) as a constrained optimization problem. We discuss necessary and sufficient conditions for the optimal solution...
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