In this paper the secrecy problem in the cognitive state-dependent interference CHANNEL is considered. In this scenario we have a primary and a cognitive transmitter-receiver pairs. The cognitive transmitter has the message of the primary sender as side information. In addition, the state of the CHANNEL is known at the cognitive encoder. Hence, the cognitive encoder uses this side information to cooperate with the primary transmitter. The message of the cognitive encoder must be secret at the primary receiver, i.e., the primary receiver act as an eavesdropper for the cognitive transmitter. An achievable rate region and an outer bound on the rate region in this CHANNEL are derived. The results are extended to the previous works as special cases.

We study an entangled two-mode coherent state within the framework of 2×2-dimensional Hilbert space. We investigate the problem of quantum teleportation of a superposition coherent state via an entangled coherent CHANNEL. By three different measures with the titles ``minimum assured fidelity (MASF)” , ``average teleportation fidelity” and ``optimal fidelity (f)” we study the quality of this kind of teleportation. Decoherence properties of the entangled coherent state due to CHANNEL losses are analysed. For a symmetric noise CHANNEL, the degradation of optimal fidelity and degree of entanglement are calculated. Also by two different measures with the titles ``concurrence” and ``entanglement of formation” we study the amount of entanglement of a decohered quantum CHANNEL and discuss its details. We demonstrate that entanglement of the decohered entangled coherent state is reduced but not throughly lost. Finally we find that the optimal fidelity of the decohered entangled coherent state is more than the classical limit and the decohered entangled coherent state may be useful for quantum teleportation.

The progress of the technology in the recent decades has caused the video transmission by communication CHANNELs to meet high demands. Therefore, many methods have been proposed to improve the quality of the video under CHANNEL errors. The aim of this paper is to increase the Peak Signal to the Noise Ratio (PSNR) for video reconstructed by the receiver. This is achieved by increasing CHANNEL encoder rate but in constant transmission rate. In the proposed method the video frames’ parts containing more energy are coded by the local CHANNEL coding inside the source encoder. Then, the resulted data is embedded in the low power frames’ parts. The proposed method is able to increase the CHANNEL coding rates without increasing the amount of the information for any frame. This method provides more robustness for video frames against CHANNEL errors. The proposed method is tested for different source coding rates and several Signals to Noise Ratio (SNRs) for CHANNEL and the obtained results are compared with a new method.