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This work tackles the issue of channel estimation in the context of non-binary-LDPC-coded OFDM systems over doubly-selective multipath channels. The properties of channel encoding are exploited to derive an iterative Wiener-filter-based estimation method using both time and frequency channel correlation. The proposed algorithm can use either soft information or hard decisions fed back by the decoder...
Advancements in channel coding theory over the past decades have been accomplished considering simple channel such as Additive White Gaussian Noise channels. Much less is known about the consequences when the standard Gaussian assumption is not fulfilled in realistic environments and, more importantly, the appropriate countermeasures. This paper studies and analyzes the performance of low-density...
Blind identification of parameters in block interleaving has been studied by some researchers. In this paper, we extend the identification algorithm to convolutional type of interleaving. In particular, our algorithm is able to blindly determine the interleaver period, interleaver depth, number of stages in each shift register of interleaver and thus de-interleave the interleaved data streams. The...
Estimation of the variance of AWGN is important to the initialization of iterative decoder, such as turbo code and LDPC code. Hence this paper puts forward a low-complexity and effective blind Gaussian variance estimator for MPSK and MQAM. The algorithm is derived from empirical characteristic function and provides a good un-biased estimation despite the knowledge of modulation type, as is proved...
Trapping sets (TSs) have been known to contribute to errors in the decoding of low-density parity-check (LDPC) codes, particularly at the high signal-to-noise ratio (SNR) region. Moreover, TSs with the same label [w; u] are considered equivalent under the automorphism of the graph of a regular code. But according to our our simulations, TSs with the same label [w; u] are producing different error...
In this paper, we proposed an efficient dual watermark scheme for image tamper detection and recovery. In the proposed watermarking algorithm each block in the image contains watermark of other two blocks, i.e. two copies of watermark of the whole image is maintained and second chance for block recovery is provided in case one copy is destroyed. The algorithm proposed by Lee and Shinfeng is unable...
In this paper, the combined normalized and offset min-sum algorithm is proposed for efficient decoding of low-density parity-check (LDPC) codes in optical and magnetic storage systems. The proposed algorithm can be considered as a general case of the normalized and offset algorithms, and offers better BER performance compared to them. The performance improvement is presented for a partial response...
We consider the problem of compression of multiple correlated sources. It is assumed that the sources are given as a sequence with neighbouring sources correlated in terms of Hamming distance. In previous work we derived a general distributed source coding (DSC) framework that uses the parity check matrix of a suitably chosen block code C1. In this paper we focus on the special case that C1 is a cyclic...
The projective geometry (PG) based low density parity check (LDPC) codes are gaining popularity due to their ease of encoding and decoding by the simple majority logic technique. These codes have a flurry of other useful properties, making them ideal candidates/codes for error correction for future wireless applications. This paper brings out a detailed study on the performance of PG codes for different...
Comparator is the key module in LDPC decoder that consumes most of the power and area. In this paper, a new comparator based on pass transistors and dynamic logic is proposed to decrease the power and the area. The comparator is implemented with full custom design at SMIC 0.18 1P6M technology. The simulation result of layout shows that the power drops by 11.4% and the area is reduced by 30% compared...
This paper studies what is the right relay protocol strategy for a low density parity check (LDPC) cooperative diversity scheme. In this scheme, an improved maximum likelihood detection (MLD) featuring Log-likelihood (LLR) combining technique is also introduced. A basic cooperative diversity scheme of a source node (S), a relay node (R) and a common destination node (D) is considered. This scheme...
The problem of decoding of maximum distance separable (MDS) discrete cosine transform (DCT) and discrete sine transform (DST) codes, which are used for error correction over real fields, is considered in this paper. A novel subspace based decoding method is proposed which has the ability to decode the entire class of MDS DCT and DST codes. Also, the proposed method has the advantage of reduced noise...
A major difficulty that plagues the practical use of Slepian-Wolf coding (and distributed source coding in general) is that the precise correlation among sources need to be known a priori. To resolve this problem, we propose an adaptive Slepian-Wolf decoder using particle filtering based belief propagation. We show through experiments that the proposed algorithm can simultaneously reconstruct a compressed...
Despite tremendous amount of research on the design of low-density parity-check (LDPC) codes with belief propagation decoding over different types of binary-input output-symmetric memoryless (BIOSM) channels, most results on this topic are based on numerical methods and optimization which do not provide much insight into the design process. In particular, systematic design of provably capacity achieving...
This paper presents a scalable and low power low-density parity-check (LDPC) decoder design for the next generation wireless handset SoC. The methodology is based on high level synthesis: PICO (program-in chip-out) tool was used to produce efficient RTL directly from a sequential un-timed C algorithm. We propose two parallel LDPC decoder architectures: (1) per-layer decoding architecture with scalable...
This paper presents a soft reliability-based binary message-passing algorithm for decoding LDPC codes. This algorithm outperforms the existing weighted bit-flipping algorithms with much less computational complexity. It is particularly effective for decoding LDPC codes constructed based on finite-geometries and finite fields. The proposed algorithm can be simplified for applications in communication...
In this paper, we consider a few iterative decoding schemes for the joint source-channel coding of correlated sources. Specifically, we consider the joint source-channel coding of two erasure correlated sources with transmission over different erasure channels. Our main interest is in determining whether or not various code ensembles can achieve the capacity region universally over varying channel...
The capacity of the symbol-asynchronous single-relay channel is investigated. Symbol asynchronism implies that the codewords transmitted from the relay and the source do not coincide in time at the destination. Due to propagation or implementation effects (e.g. mis-synchronized clocks), symbol asynchronism occurs in many practical situations. In ad hoc scenarios, such as sensor networks, achieving...
In this paper we investigate the performance of linear interactive encoding and decoding based on syndrome accumulation(SA-IED) over binary LDPC ensembles. Assume that the source alphabet is GF(2), and the side information alphabet is finite. It is shown that we can construct universal SA-IED schemes, which are asymptotically optimal for any stationary ergodic source-side information pair. Our analysis...
The failures of iterative decoders for low-density parity-check (LDPC) codes on the additive white Gaussian noise channel (AWGNC) and the binary symmetric channel (BSC) can be understood in terms of combinatorial objects known as trapping sets. In this paper, we derive a systematic method to identify the most relevant trapping sets for decoding over the BSC in the error floor region. We elaborate...
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