A Compression Resistant Steganography Based on Differential Manchester Code

In the field of image steganography research, more and more attention is paid to the importance of stego image robustness. In order to make steganography accessible from laboratory to practical applications, it becomes critical that the stego images can resist JPEG compression from transmission channel. In this paper, an image steganography algorithm with strong robustness to resist JPEG compression is proposed. First, the robust cover elements are selected using the sign of DCT coefficients which are kept constant before and after JPEG compression. Additionally, a distortion function and a weighted cost adjustment method are designed to assign an appropriate cost to each candidate DCT coefficient. Finally, the message is embedded in the cover image which has minimal embedding distortion by flipping the signs of DCT coefficients, while differential Manchester code is applied to the element positions to obtain the location feature. Compared with the prior art, our algorithm has better undetectability and stronger robustness, and it can resist the attacks from the social network platforms such as Facebook, Twitter, and WeChat.

MODELING A COMMUNICATION SYSTEM USING LINEAR CODES AND EVALUATING THEIR EFFECTIVENESS

The paper presents some methods of linear coding: NRZ-L (Non-Return to Zero Level), NRZ-M (Non-Return to Zero Mark), RZ-AMI (Return to Zero Alternate Mark Inversion) and Manchester code. On the NI ELVIS II+ and module Emona DATEx it was succeeded to realize the prototype of digital communication system and estimate efficiency of signal demodulation.

A multi-tag anti-collision protocol based on 8-ary adaptive pruning query tree

In order to solve the problem of multi-tag anti-collision in radio frequency identification systems, a multi-tag anti-collision protocol based on 8-ary adaptive pruning query tree is proposed in this article. According to Manchester code, the highest collision bit can be detected. In the process of tag identification, the protocol only locks the target on the three consecutive bits which start from the highest collision bit. The protocol has two tag identification mechanisms, and which one is chosen is determined by the value of collision coefficient. Using the collision information characteristics of the three bits, idle timeslots are evitable, and some collision timeslots are eliminated at the same time. The 8-ary adaptive pruning query tree protocol fully takes into account several important performance indicators such as the number of query timeslots, communication complexity, transmission delay, and throughput. Both theoretical analysis and simulation results show that this protocol performs better than other tree-based anti-collision protocols. The throughput of 8-ary adaptive pruning query tree protocol remains approximately 0.625.

The Manchester Coded Data Based OFDM (MCOFDM)

This paper shows a new DWT based OFDM algorithm which significantly simplifies signal processing in the transmitter and receiver. Unlike conventional DWT based OFDM a new algorithm does not use digital modulation of subcarriers either IDWT in the transmitter. The output signal from the transmitter is formed by summing the signals on the individual subchannels, encoded with the Manchester code and sampled at appropriate frequencies. In the receiver, the channel signal and data is reconstructed using DWT and Haar wavelet. Although the signal transmission is achieved using amplitude modulation, the paper shows that BER performance is commensurable to BPSK or DMWT based OFDM in the presence of AWGN.