46 research outputs found
Achieving Secrecy Capacity of the Gaussian Wiretap Channel with Polar Lattices
In this work, an explicit wiretap coding scheme based on polar lattices is
proposed to achieve the secrecy capacity of the additive white Gaussian noise
(AWGN) wiretap channel. Firstly, polar lattices are used to construct
secrecy-good lattices for the mod- Gaussian wiretap channel. Then we
propose an explicit shaping scheme to remove this mod- front end and
extend polar lattices to the genuine Gaussian wiretap channel. The shaping
technique is based on the lattice Gaussian distribution, which leads to a
binary asymmetric channel at each level for the multilevel lattice codes. By
employing the asymmetric polar coding technique, we construct an AWGN-good
lattice and a secrecy-good lattice with optimal shaping simultaneously. As a
result, the encoding complexity for the sender and the decoding complexity for
the legitimate receiver are both O(N logN log(logN)). The proposed scheme is
proven to be semantically secure.Comment: Submitted to IEEE Trans. Information Theory, revised. This is the
authors' own version of the pape
LDPC Code Design for the BPSK-constrained Gaussian Wiretap Channel
A coding scheme based on irregular low-density parity-check (LDPC) codes is
proposed to send secret messages from a source over the Gaussian wiretap
channel to a destination in the presence of a wiretapper, with the restriction
that the source can send only binary phase-shift keyed (BPSK) symbols. The
secrecy performance of the proposed coding scheme is measured by the secret
message rate through the wiretap channel as well as the equivocation rate about
the message at the wiretapper. A code search procedure is suggested to obtain
irregular LDPC codes that achieve good secrecy performance in such context.Comment: submitted to IEEE GLOBECOM 2011 - Communication Theory Symposiu
Recommended from our members
Coding mechanisms for communication and compression : analysis of wireless channels and DNA sequencing
textThis thesis comprises of two related but distinct components: Coding arguments for communication channels and information-theoretic analysis for haplotype assembly. The common thread for both problems is utilizing information and coding theoretic principles in understanding their underlying mechanisms. For the first class of problems, I study two practical challenges that prevent optimal discrete codes utilizing in real communication and compression systems, namely, coding over analog alphabet and fading. In particular, I use an expansion coding scheme to convert the original analog channel coding and source coding problems into a set of independent discrete subproblems. By adopting optimal discrete codes over the expanded levels, this low-complexity coding scheme can approach Shannon limit perfectly or in ratio. Meanwhile, I design a polar coding scheme to deal with the unstable state of fading channels. This novel coding mechanism of hierarchically utilizing different types of polar codes has been proved to be ergodic capacity achievable for several fading systems, without channel state information known at the transmitter. For the second class of problems, I build an information-theoretic view for haplotype assembly. More precisely, the recovery of the target pair of haplotype sequences using short reads is rephrased as the joint source-channel coding problem. Two binary messages, representing haplotypes and chromosome memberships of reads, are encoded and transmitted over a channel with erasures and errors, where the channel model reflects salient features of highthroughput sequencing. The focus is on determining the required number of reads for reliable haplotype reconstruction.Electrical and Computer Engineerin
Power allocation and signal labelling on physical layer security
PhD ThesisSecure communications between legitimate users have received considerable
attention recently. Transmission cryptography, which introduces
secrecy on the network layer, is heavily relied on conventionally to secure
communications. However, it is theoretically possible to break the
encryption if unlimited computational resource is provided. As a result,
physical layer security becomes a hot topic as it provides perfect secrecy
from an information theory perspective. The study of physical layer
security on real communication system model is challenging and important,
as the previous researches are mainly focusing on the Gaussian
input model which is not practically implementable.
In this thesis, the physical layer security of wireless networks employing
finite-alphabet input schemes are studied. In particular, firstly, the secrecy
capacity of the single-input single-output (SISO) wiretap channel
model with coded modulation (CM) and bit-interleaved coded modulation
(BICM) is derived in closed-form, while a fast, sub-optimal power
control policy (PCP) is presented to maximize the secrecy capacity performance.
Since finite-alphabet input schemes achieve maximum secrecy
capacity at medium SNR range, the maximum amount of energy that
the destination can harvest from the transmission while satisfying the
secrecy rate constraint is computed. Secondly, the effects of mapping
techniques on secrecy capacity of BICM scheme are investigated, the secrecy
capacity performances of various known mappings are compared on
8PSK, 16QAM and (1,5,10) constellations, showing that Gray mapping
obtains lowest secrecy capacity value at high SNRs. We propose a new
mapping algorithm, called maximum error event (MEE), to optimize the
secrecy capacity over a wide range of SNRs. At low SNR, MEE mapping
achieves a lower secrecy rate than other well-known mappings, but
at medium-to-high SNRs MEE mapping achieves a significantly higher
secrecy rate over a wide range of SNRs. Finally, the secrecy capacity and
power allocation algorithm (PA) of finite-alphabet input wiretap channels
with decode-and-forward (DF) relays are proposed, the simulation
results are compared with the equal power allocation algorithm
Lecture Notes on Network Information Theory
These lecture notes have been converted to a book titled Network Information
Theory published recently by Cambridge University Press. This book provides a
significantly expanded exposition of the material in the lecture notes as well
as problems and bibliographic notes at the end of each chapter. The authors are
currently preparing a set of slides based on the book that will be posted in
the second half of 2012. More information about the book can be found at
http://www.cambridge.org/9781107008731/. The previous (and obsolete) version of
the lecture notes can be found at http://arxiv.org/abs/1001.3404v4/
Coding and Signal Processing for Secure Wireless Communication
Wireless communication networks are widely deployed today and the networks are used in many applications which require that the data transmitted be secure. Due to the open nature of wireless systems, it is important to have a fundamental understanding of coding schemes that allow for simultaneously secure and reliable transmission. The information theoretic approach is able to give us this fundamental insight into the nature of the coding schemes required for security. The security issue is approached by focusing on the confidentiality of message transmission and reception at the physical layer. The goal is to design coding and signal processing schemes that provide security, in the information theoretic sense. In so doing, we are able to prove the simultaneously secure and reliable transmission rates for different network building blocks. The multi-receiver broadcast channel is an important network building block, where the rate region for the channel without security constraints is still unknown. In the thesis this channel is investigated with security constraints, and the secure and reliable rates are derived for the proposed coding scheme using a random coding argument. Cooperative relaying is next applied to the wiretap channel, the fundamental physical layer model for the communication security problem, and signal processing techniques are used to show that the secure rate can be improved in situations where the secure rate was small due to the eavesdropper enjoying a more favorable channel condition compared to the legitimate receiver. Finally, structured lattice codes are used in the wiretap channel instead of unstructured random codes, used in the vast majority of the work so far. We show that lattice coding and decoding can achieve the secrecy rate of the Gaussian wiretap channel; this is an important step towards realizing practical, explicit codes for the wiretap channel