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The paper presents an analysis of performances of asymmetric turbo codes over Rayleigh fading channels, using BPSK modulation. The simulations are performed for the length of the interleaver L=100, considering two scenarios: the side information is available and it is not available for the channel, respectively. For this analysis, the performances of asymmetric turbo codes are higher than those of...
We analyze the lossless compression for a large class of discrete complete and memoryless sources performed by a generalized Huffman with an alphabet consisting of M letters. Given the number of source messages, N, the alphabet size, M, and the number of code words, p, on each level in the graph, excepting the last two ones, we have determined the unknown encoding parameters, that is, the number n...
This paper presents new results of the D-ary Huffman tree. These results are used to prove that the maximum value of the average codeword length is obtained for the uniform distribution. The upper bound computed in this paper is higher than the value obtained for Huffman codes with minimum redundancy.
Two search methods of quadratic permutation polynomials (QPP) for interleavers used in turbo codes are proposed. These methods lead to larger minimum distances and smaller multiplicities compared to interleavers proposed by Takeshita. The search is accomplished in a limited set of polynomials, that is, those for which the spreading factor and Omega' metric are maximum. The minimum distance is computed...
In this paper an information analysis for lossless compression of a large class of discrete sources is performed. The lossless compression is performed by means of a Huffman code with an alphabet A of size M. Matrix characterization of the encoding as a source with memory is realized. The information quantities H(S,A), H(S), H(A), H(A|S), H(S|A), I(S,A) as well as the minimum average code word length...
This paper presents the lower bound on the average codeword length of the D-ary Huffman codes. Two extreme cases are analyzed: the quasi-uniform and anti-uniform Huffman codes. For each case the codeword lengths are computed. The histogram of the average codeword length obtained by simulation confirms the bound on the average codeword lengths. The lower bound computed in this paper is lower than the...
In this paper M-ary antiuniform Huffman codes are considered. In this case the source probability distribution assures the minimum average codeword length, by diversifying only one node on each level in the tree graph. A matrix characterization of the M-ary antiuniform Huffman code as a source with memory is performed and the information quantities are derived.
A method to increase the minimum distance for turbo codes with Welch-Costas interleavers is proposed. The minimum distance obtained by the proposed method is comparable to that corresponding to the S-random interleaver [1]. A slight increase of memory is required compared to the classic Welch-Costas interleaver [2].
An algorithm to increase the S parameter up to a value allowed by the reasonable generating of a S -random interleaver is presented. The method is appropriate for both random and determinist interleavers, as Welch-Costas, Takeshita-Costello or the one given by the UMTS standard. Concurrently, the algorithm realizes a randomization of the permutation, the dispersion being typical for a random interleaver,...
For the case in which the code alphabet consists of M letters, we derive the optimum probability distribution of a discrete source that assures the minimum average codeword length. For the case of Huffman encoding, we derive the upper and lower bounds of average codeword length.
Assuming certain costs for symbols at the input and output of a noisy channel, the quantitative-qualitative entropies, as well as the average mutual information are determined. It is also shown that the relationships between these quantities are preserved.
The problem of subband coding with crossband prediction of a wide sense stationary Gaussian source is analyzed. The analysis is performed both in case of high rate encoding, i.e., the case of small distortion and in the case when an additive noise model for the quantizer is adopted. In both cases the noncausal and causal prediction filters are derived. The prediction filters results of infinite impulse...
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