Nested turbo codes for the costa problem

Driven by applications in data-hiding, MIMO broadcast channel coding, precoding for interference cancellation, and transmitter cooperation in wireless networks, Costa coding has lately become a very active research area. In this paper, we first offer code design guidelines in terms of source- channel coding for algebraic binning. We then address practical code design based on nested lattice codes and propose nested turbo codes using turbo-like trellis-coded quantization (TCQ) for source coding and turbo trellis-coded modulation (TTCM) for channel coding. Compared to TCQ, turbo-like TCQ offers structural similarity between the source and channel coding components, leading to more efficient nesting with TTCM and better source coding performance. Due to the difference in effective dimensionality between turbo-like TCQ and TTCM, there is a performance tradeoff between these two components when they are nested together, meaning that the performance of turbo-like TCQ worsens as the TTCM code becomes stronger and vice versa. Optimization of this performance tradeoff leads to our code design that outperforms existing TCQ/TCM and TCQ/TTCM constructions and exhibits a gap of 0.94, 1.42 and 2.65 dB to the Costa capacity at 2.0, 1.0, and 0.5 bits/sample, respectively

Design of information hiding algorithm for multi-link network transmission channel

Traditional channel information hiding algorithms based on m-sequence for multi-link network transmission, which apply m-sequence to channel coding information hiding system, do not analyze the upper limit of hiding capacity of multi-link network transmission channel system, and do not consider the hidden danger of overlapping secret information when embedding secret information is too large. It has the defects of low efficiency, poor accuracy and large storage cost. This paper designs an information hiding algorithm for multi-link network transmission channel based on secondary positioning, it uses RS code M public key cryptosystem to pre-process secret information and improve the security of information; calculates the upper limit of hiding capacity of multi-link network transmission channel system through information hiding capacity analysis model, and determines whether the hiding capacity exceeds the secret information. Secondary location and cyclic shift mechanism are introduced to improve the randomness of location selection and avoid overlapping of secret information. The experimental results show that the proposed algorithm has a great advantage in memory cost. When the channel SNR is 0 dB and 8 dB, the normalization coefficients are 0.87 and 1.04, respectively. This shows that the algorithm has a high accuracy in extracting secret information. The average time spent on hiding information is 2.04 s, indicating that the algorithm has high information hiding rate and storage efficiency

ERROR CORRECTION CODE-BASED EMBEDDING IN ADAPTIVE RATE WIRELESS COMMUNICATION SYSTEMS

In this dissertation, we investigated the methods for development of embedded channels within error correction mechanisms utilized to support adaptive rate communication systems. We developed an error correction code-based embedding scheme suitable for application in modern wireless data communication standards. We specifically implemented the scheme for both low-density parity check block codes and binary convolutional codes. While error correction code-based information hiding has been previously presented in literature, we sought to take advantage of the fact that these wireless systems have the ability to change their modulation and coding rates in response to changing channel conditions. We utilized this functionality to incorporate knowledge of the channel state into the scheme, which led to an increase in embedding capacity. We conducted extensive simulations to establish the performance of our embedding methodologies. Results from these simulations enabled the development of models to characterize the behavior of the embedded channels and identify sources of distortion in the underlying communication system. Finally, we developed expressions to define limitations on the capacity of these channels subject to a variety of constraints, including the selected modulation type and coding rate of the communication system, the current channel state, and the specific embedding implementation.Commander, United States NavyApproved for public release; distribution is unlimited

Non-linear echo cancellation - a Bayesian approach

Echo cancellation literature is reviewed, then a Bayesian model is introduced and it is shown how how it can be used to model and fit nonlinear channels. An algorithm for cancellation of echo over a nonlinear channel is developed and tested. It is shown that this nonlinear algorithm converges for both linear and nonlinear channels and is superior to linear echo cancellation for canceling an echo through a nonlinear echo-path channel

A DWT-BCH code based Video Steganography by employing Variable bit length Algorithm

Due to the high speed of Internet we can easily transfer video data over the Internet, but people are worried about their data being hacked by unauthorized users. Inside the host medium (text, audio, image and video) we can embed the secret message in Steganography. Video Steganography is a significant method for data hiding. In this work, a variable bit length Video Steganography algorithm is proposed. To immune the secret data, it is first encoded using BCH codes, where the message bits of length k will be converted to a codeword of length n. Depending on the wavelet coefficient values of DWT(Discrete wavelet transform), secret data are embedded into the middle and high frequencies. The results demonstrate better results than in [1]