Differential distributed space-time coding (DDSTC) has been proved to be suitable for wireless relay networks, since it can provide spatial diversity without the need for channel state information at neither the transmitter nor the receiver side. However, DDSTC suffers from significant error floor in fast-fading channel conditions with high Doppler frequencies due to rapid time variations. For this reason, multiple-symbol differential detection (MSDD) has been proposed in the past, where the detection process involves a larger window size of the received symbols. So far, differential detection for vehicle-tovehicle (V2V) networks has been studied only for single Rayleigh channels. However, experimental and theoretical studies report that double Rayleigh can be considered as an appropriate fading channel model for V2V networks. In this paper, we assess the error performance of a DDSTC scheme operating in a V2V network using MSDD. Simulation results confirm that the error performance of such a system can be improved significantly with MSDD under different channel time-variation scenarios.

In this paper, we investigate the robustness achieved by hard-input hard-output (HIHO) turbo product code (TPC) in a grayscale image watermarking. The TPC scheme is based on the concatenation of a BCH product code. The general concept of the TPC is to construct two or more simple codes in order to achieve remarkable error performance. Unlike many proposed algorithms in the literature, HIHO-TPC require a manageable complexity encoding and decoding algorithms. Firstly, the data in the logotype (logo) is encoded using TPC and then inserted in the image. Different grayscale images are investigated and evaluated in terms of robustness to different photometric attacks by using Stirmark software package. Experimental results show that the proposed blind watermarking algorithm has a strong ability of extracting the embedded logo in different attacks such as JPEG compression, cropping, and 3x3 median filtering.

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