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In some applications the transmission of discrete-time but continuous-amplitude (or multilevel) source symbols is required which might be more bandwidth efficient than conventional digital transmission. An appropriate method is to apply a source channel mapping (SCM) of M source symbols to N channel symbols. A geometrical approach for SCM has been introduced by Shannon and Kotel'nikov (Shannon-Kotel'nikov...
A new adaptive recursive maximum likelihood decoding algorithm using ordered statistics is proposed. The average computational complexity of the algorithm is considerably small compared with the known algorithms. Preliminary simulation results for the (64,22,16) Reed-Muller code and the (64,24,16) extended BCH code are shown. The average number of additions and comparisons on soft-decision values...
In this paper, we investigate the signal-to-noise ratio (SNR) sensitivity of the Log-MAP turbo decoder over Rayleigh fading channels. It is shown that the use of the channel reliability factor proposed by Frenger is equivalent to an SNR underestimation when the channel estimate is not perfect. In addition, we propose s simplified method to compute the channel reliability factor, which leads to reduction...
Multiple-input double-output (MIDO) codes are important in future wireless communications, where the portable end-user device is physically small and will typically contain maximum two receive antennas. Especially tempting is the 4×2 channel, where the four transmitters can either be all at one station, or separated between two different stations. Such channels optimally employ rate-two space-time...
In this work, we focus on a specific practical constraint on sequential-type decoding algorithms, that is, finite stack size. Under such a practical constraint, the path deletion policy that is required when the stack exceeds its upper limit becomes essential in performance and decoding complexity. We then examined several path deletion schemes for sequential-type decoding algorithms that can produce...
In diversity embedded coding, information streams are divided into two sub-streams with different priorities. If the optimal DMT performance of each coded stream can be achieved, then such code is said to be successive refinable. For the cases of SISO, SIMO, and MISO Rayleigh slow fading channels, Diggavi and Tse had shown that superposition coding with successive cancellation receiver achieves successive...
We investigate adaptive single-trial error/erasure decoding of binary codes whose decoder is able to correct ε errors and τ erasures if λε + ≤ <; dmin -1. Thereby, dmin is the minimum Hamming distance and λ ϵ R, 1 <; λ <; 2, is the tradeoff parameter between errors and erasures. The error/erasure decoder allows to exploit soft information by treating a set of most unreliable received symbols...
In vivo imaging techniques applied to small animals are important tools in basic research. Scintigraphic planar and tomographic images allow in vivo functional expression of the protocol's effect on the animal's organs to be assessed. In that way, long term dynamical studies can be developed on the same animal, which can be used as its own control, helping to reduce statistical uncertainties, to cut...
In non-block “streaming” data settings it has been observed that the availability of feedback dramatically changes the attainable communication reliability as a function of delay. The codebooks upon which these results depend contain a special and extremely reliable “red alert” message, used to indicate to the decoder when its best guess of the prior transmission is erroneous. In this paper we develop...
Polar codes have been recently proposed as the first low complexity class of codes that can provably achieve the capacity of symmetric binary-input memoryless channels. Here, we study the bit error rate performance of finite-length polar codes under Belief Propagation (BP) decoding. We analyze the stopping sets of polar codes and the size of the minimal stopping set, called “stopping distance”. Stopping...
Space-time block coded spatial modulation (STBC-SM), which employs space-time block coding (STBC) for spatial modulation (SM), is proposed as a new multiple-input multiple-output (MIMO) transmission scheme. In the STBC-SM scheme, the transmitted information symbols are expanded not only to the space and time domains but also to the spatial (antenna) domain, therefore both core STBC and antenna indices...
Lattice reduction algorithms, such as the LLL algorithm, have been proposed as preprocessing tools in order to enhance the performance of suboptimal receivers in MIMO communications. In this paper we introduce a new kind of lattice reduction-aided decoding technique, called augmented lattice reduction, which recovers the transmitted vector directly from the change of basis matrix, and therefore doesn't...
Turbo equalization is a powerful method to iteratively detect and decode convolutionally encoded data that is corrupted by inter symbol interference (ISI) and Gaussian noise. It is based on the exchange of reliability information between the equalizer and the decoder, which is typically some sort of maximum a posteriori (MAP) decoder. While the number of remaining errors in the received sequence decreases...
Applying the max-product (and belief-propagation) algorithms to loopy graphs is now quite popular for constraint satisfaction problems. This is largely due to their low computational complexity and impressive performance in practice. Still, there is no general understanding of the conditions required for convergence and/or the optimality of converged solutions. This paper presents an analysis of weighted...
Recently, it was observed that spatially-coupled LDPC code ensembles approach the Shannon capacity for a class of binary-input memoryless symmetric (BMS) channels. The fundamental reason for this was attributed to a threshold saturation phenomena derived in. In particular, it was shown that the belief propagation (BP) threshold of the spatially coupled codes is equal to the maximum a posteriori (MAP)...
A reduced-complexity modified decoding algorithm for turbo trellis-coded modulation (TTCM) is proposed and evaluated in terms of complexity and bit error rate (BER) performance in an additive white Gaussian noise (AWGN) channel. A novel method is derived from the Chebyshev inequality. In this approach, the max* operation is performed on n≥2 arguments, thus the recursive calculations are avoided and...
The sphere decoding algorithm for signal transmitted on multiple antennas channel is considered. In this paper, the preprocessing stage is analyzed in order to seek a reduced complexity and some improvements are made to enhance the performance. The computer simulation results show that the improved algorithm by applying Pohst Enumeration with selected initial radius is more efficient than that by...
Multiple-input multiple-output (MIMO) single carrier frequency division multiple access (SC-FDMA), which combines the advantage of spatial and frequency diversities with frequency domain equalizers (FDE), has drawn great attention recently. Among all possible detection techniques, maximum-likelihood detection (MLD) is optimal, but its exponentially computational complexity precludes its use in practical...
In this paper, we propose a modification to Belief Propagation (BP) decoding algorithm for LDPC codes. The modification is to attenuate the check to bit extrinsic logarithm likelihood ratio by a factor α, when sudden sign change happens. This modification can be applied to both the standard BP algorithm and the joint row and column (JRC) BP algorithm. Simulation results show that the BER and WER performance...
This paper proposes an OFDM based transmission scheme for asynchronous amplify-and-forward cooperative systems with two relay nodes over frequency-selective channels. To combat the inter-symbol interference from multi-path fading and timing errors, the cyclic prefix (CP) is used at both the source node and relay nodes. Unlike using IDFT and DFT modulation for two consecutive OFDM blocks respectively,...
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