In this article, a novel class of fountain codes with feedback, called relative-entropy-based fountain (REF) codes, is proposed. The transmitter of REF codes adapts the degrees of encoded symbols to make the degree di...
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In this article, a novel class of fountain codes with feedback, called relative-entropy-based fountain (REF) codes, is proposed. The transmitter of REF codes adapts the degrees of encoded symbols to make the degree distribution at the receiver close to the robust soliton distribution, where the distance between two distributions is measured by relative entropy. The proposed REF codes are shown to achieve excellent intermediate performance over binary erasure channels (BECs), and binary-input additive white gaussian noise channels (BI-AWGNCs) for both unicast, and multicast scenarios. For multicast, a non-uniform input symbol selection scheme is proposed to enhance the performance of REF codes. Furthermore, since the feedback is imprecise under noisy channels, the concept "belief" is introduced to improve the reliability of REF codes. Theoretical analysis is performed for the proposed REF codes, with an upper bound, and an approximate lower bound of the intermediate performance of REF codes over BECs derived. Both theoretical analysis, and simulations show that the proposed REF codes outperform the state-of-the-art fountain codes with feedback, in terms of the intermediate performance, with low overhead.
In this paper, we study spatially coupled low-density parity-check (SC-LDPC) codes over finite fields GF(q), q >= 2, and develop design rules for q-ary SC-LDPC code ensembles based on their iterative belief propaga...
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In this paper, we study spatially coupled low-density parity-check (SC-LDPC) codes over finite fields GF(q), q >= 2, and develop design rules for q-ary SC-LDPC code ensembles based on their iterative belief propagation decoding thresholds, with particular emphasis on low-latency windowed decoding (WD). We consider transmission over both the binary erasure channel (BEC) and the binary-input additive white gaussian noise channel (BIAWGNC) and present results for a variety of (J, K)-regular SC-LDPC code ensembles constructed over GF(q) using protographs. Thresholds are calculated using the protograph versions of q-ary density evolution (for the BEC) and the q-ary extrinsic information transfer analysis (for the BIAWGNC). We show that the WD of q-ary SC-LDPC codes provides significant threshold gains compared with corresponding (uncoupled) q-ary LDPC block code (LDPC-BC) ensembles when the window size W is large enough and that these gains increase as the finite-field size q = 2(m) increases. Moreover, we demonstrate that the new design rules provide WD thresholds that are close to capacity, even when both m and W are relatively small (thereby reducing decoding complexity and latency). The analysis further shows that, compared with standard flooding-schedule decoding, the WD of q-ary SC-LDPC code ensembles results in significant reductions in both the decoding complexity and the decoding latency and that these reductions increase as m increases. For the applications with a near-threshold performance requirement and a constraint on decoding latency, we show that using q-ary SC-LDPC code ensembles, with moderate q > 2, instead of their binary counterparts results in reduced decoding complexity.
In this study, the author investigates the practical limitation of the recently proposed embedded cryptographic signature authentication scheme at the physical layer. By employing the log-likelihood ratio of a tag bit...
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In this study, the author investigates the practical limitation of the recently proposed embedded cryptographic signature authentication scheme at the physical layer. By employing the log-likelihood ratio of a tag bit and its approximation, the author shows that the equivalent authentication channel observed by the secondary receiver can be viewed as a binary-input additive white gaussian noise channel. Then, the sphere-packing lower bound can be employed to show the transmission capability for practical finite-length authentication tags. To achieve the same effective coverage area for both the primary and secondary receivers, it essentially requires efficient low-rate channel coding schemes with near sphere-packing-bound performance at the secondary receiver, which contrasts sharply with the pessimistic conclusion of Jiang et al.
We propose a technique to design finite-length irregular low-density parity-check (LDPC) codes over the binary-inputadditivewhitegaussiannoise (AWGN) channel with good performance in both the waterfall and the err...
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ISBN:
(纸本)9781457705953
We propose a technique to design finite-length irregular low-density parity-check (LDPC) codes over the binary-inputadditivewhitegaussiannoise (AWGN) channel with good performance in both the waterfall and the error floor region. The design process starts from a protograph which embodies a desirable degree distribution. This protograph is then lifted cyclically to a certain block length of interest. The lift is designed carefully to satisfy a certain approximate cycle extrinsic message degree (ACE) spectrum. The target ACE spectrum is one with extremal properties, implying a good error floor performance for the designed code. The proposed construction results in quasi-cyclic codes which are attractive in practice due to simple encoder and decoder implementation. Simulation results are provided to demonstrate the effectiveness of the proposed construction in comparison with similar existing constructions.
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