2,729 research outputs found
Spatially-Coupled LDPC Codes for Decode-and-Forward Relaying of Two Correlated Sources over the BEC
We present a decode-and-forward transmission scheme based on
spatially-coupled low-density parity-check (SC-LDPC) codes for a network
consisting of two (possibly correlated) sources, one relay, and one
destination. The links between the nodes are modeled as binary erasure
channels. Joint source-channel coding with joint channel decoding is used to
exploit the correlation. The relay performs network coding. We derive
analytical bounds on the achievable rates for the binary erasure time-division
multiple-access relay channel with correlated sources. We then design bilayer
SC-LDPC codes and analyze their asymptotic performance for this scenario. We
prove analytically that the proposed coding scheme achieves the theoretical
limit for symmetric channel conditions and uncorrelated sources. Using density
evolution, we furthermore demonstrate that our scheme approaches the
theoretical limit also for non-symmetric channel conditions and when the
sources are correlated, and we observe the threshold saturation effect that is
typical for spatially-coupled systems. Finally, we give simulation results for
large block lengths, which validate the DE analysis.Comment: IEEE Transactions on Communications, to appea
Distributed Joint Source-Channel Coding in Wireless Sensor Networks
Considering the fact that sensors are energy-limited and the wireless channel conditions in wireless sensor networks, there is an urgent need for a low-complexity coding method with high compression ratio and noise-resisted features. This paper reviews the progress made in distributed joint source-channel coding which can address this issue. The main existing deployments, from the theory to practice, of distributed joint source-channel coding over the independent channels, the multiple access channels and the broadcast channels are introduced, respectively. To this end, we also present a practical scheme for compressing multiple correlated sources over the independent channels. The simulation results demonstrate the desired efficiency
The Three-User Finite-Field Multi-Way Relay Channel with Correlated Sources
This paper studies the three-user finite-field multi-way relay channel, where
the users exchange messages via a relay. The messages are arbitrarily
correlated, and the finite-field channel is linear and is subject to additive
noise of arbitrary distribution. The problem is to determine the minimum
achievable source-channel rate, defined as channel uses per source symbol
needed for reliable communication. We combine Slepian-Wolf source coding and
functional-decode-forward channel coding to obtain the solution for two classes
of source and channel combinations. Furthermore, for correlated sources that
have their common information equal their mutual information, we propose a new
coding scheme to achieve the minimum source-channel rate.Comment: Author's final version (accepted and to appear in IEEE Transactions
on Communications
Channel Optimized Distributed Multiple Description Coding
In this paper, channel optimized distributed multiple description vector
quantization (CDMD) schemes are presented for distributed source coding in
symmetric and asymmetric settings. The CDMD encoder is designed using a
deterministic annealing approach over noisy channels with packet loss. A
minimum mean squared error asymmetric CDMD decoder is proposed for effective
reconstruction of a source, utilizing the side information (SI) and its
corresponding received descriptions. The proposed iterative symmetric CDMD
decoder jointly reconstructs the symbols of multiple correlated sources. Two
types of symmetric CDMD decoders, namely the estimated-SI and the soft-SI
decoders, are presented which respectively exploit the reconstructed symbols
and a posteriori probabilities of other sources as SI in iterations. In a
multiple source CDMD setting, for reconstruction of a source, three methods are
proposed to select another source as its SI during the decoding. The methods
operate based on minimum physical distance (in a wireless sensor network
setting), maximum mutual information and minimum end-to-end distortion. The
performance of the proposed systems and algorithms are evaluated and compared
in detail.Comment: Submitted to IEEE Transaction on Signal Processin
Feedback Power Control Strategies in Wireless Sensor Networks with Joint Channel Decoding
In this paper, we derive feedback power control strategies for block-faded multiple access schemes with correlated sources and joint channel decoding (JCD). In particular, upon the derivation of the feasible signal-to-noise ratio (SNR) region for the considered multiple access schemes, i.e., the multidimensional SNR region where error-free communications are, in principle, possible, two feedback power control strategies are proposed: (i) a classical feedback power control strategy, which aims at equalizing all link SNRs at the access point (AP), and (ii) an innovative optimized feedback power control strategy, which tries to make the network operational point fall in the feasible SNR region at the lowest overall transmit energy consumption. These strategies will be referred to as “balanced SNR” and “unbalanced SNR,” respectively. While they require, in principle, an unlimited power control range at the sources, we also propose practical versions with a limited power control range. We preliminary consider a scenario with orthogonal links and ideal feedback. Then, we analyze the robustness of the proposed power control strategies to possible non-idealities, in terms of residual multiple access interference and noisy feedback channels. Finally, we successfully apply the proposed feedback power control strategies to a limiting case of the class of considered multiple access schemes, namely a central estimating officer (CEO) scenario, where the sensors observe noisy versions of a common binary information sequence and the AP's goal is to estimate this sequence by properly fusing the soft-output information output by the JCD algorithm
Joint Channel-Network Coding Strategies for Networks with Low Complexity Relays
We investigate joint network and channel coding schemes for networks when
relay nodes are not capable of performing channel coding operations. Rather,
channel encoding is performed at the source node while channel decoding is done
only at the destination nodes. We examine three different decoding strategies:
independent network-then-channel decoding, serial network and channel decoding,
and joint network and channel decoding. Furthermore, we describe how to
implement such joint network and channel decoding using iteratively decodable
error correction codes. Using simple networks as a model, we derive achievable
rate regions and use simulations to demonstrate the effectiveness of the three
decoders.Comment: accepted and to appear in European Transactions on Telecommunication
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