1,520 research outputs found
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
Optimal Watermark Embedding and Detection Strategies Under Limited Detection Resources
An information-theoretic approach is proposed to watermark embedding and
detection under limited detector resources. First, we consider the attack-free
scenario under which asymptotically optimal decision regions in the
Neyman-Pearson sense are proposed, along with the optimal embedding rule.
Later, we explore the case of zero-mean i.i.d. Gaussian covertext distribution
with unknown variance under the attack-free scenario. For this case, we propose
a lower bound on the exponential decay rate of the false-negative probability
and prove that the optimal embedding and detecting strategy is superior to the
customary linear, additive embedding strategy in the exponential sense.
Finally, these results are extended to the case of memoryless attacks and
general worst case attacks. Optimal decision regions and embedding rules are
offered, and the worst attack channel is identified.Comment: 36 pages, 5 figures. Revised version. Submitted to IEEE Transactions
on Information Theor
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
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