In this paper, we propose a simple peak power reduction (PPR) method based on adaptive inversion of parity-check block of codeword in bch-coded OFDM system. In the proposed method, the entire parity-check block of the...
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In this paper, we propose a simple peak power reduction (PPR) method based on adaptive inversion of parity-check block of codeword in bch-coded OFDM system. In the proposed method, the entire parity-check block of the codeword is adaptively inversed by multiplying weighting factors (WFs) so as to minimize PAPR of the OFDM signal, symbol-by-symbol. At the receiver, these WFs are estimated based on the property of bch decoding. When the primitive bchcode with single error correction such as (31, 26) code is used, to estimate the WFs, the proposed method employs a significant bit protection method which assigns a significant bit to the best subcarrier selected among all possible subcarriers. With computer simulation, when (31,26), (31,21) and (32,21) bchcodes are employed, PAPR of the OFDM signal at the CCDF (Complementary Cumulative Distribution Function) of 10(-4) is reduced by about 1.9, 2.5 and 2.5 dB by applying the PPR method, while achieving the BER performance comparable to the case with the perfect VVT estimation in exponentially decaying 12-path Rayleigh fading condition.
We present two families of constacyclic linear codes with large automorphism groups. The codes are obtained from the twisted tensor product construction.
We present two families of constacyclic linear codes with large automorphism groups. The codes are obtained from the twisted tensor product construction.
Only primitive binary cyclic codes of length n = 2m - 1 are considered. A bch-code with designed distance-delta is denoted B(n,delta). A bch-code is always a narrow-sense bch-code. A codeword is identified with its lo...
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Only primitive binary cyclic codes of length n = 2m - 1 are considered. A bch-code with designed distance-delta is denoted B(n,delta). A bch-code is always a narrow-sense bch-code. A codeword is identified with its locator polynomial, whose coefficients are the symmetric functions of the locators. The definition of the code by its zeros-set involves some properties for the power sums of the locators. Moreover, the symmetric functions and the power sums of the locators are related to Newton's identities. First presented is an algebraic point of view in order to prove or disprove the existence of words of a given weight in a code. The main tool is symbolic computation software to explore Newton's identities. The principal result is the true minimum distance of some bch-codes of length 255 and 511, which were not known. In a second part, the minimum weight codewords of the codes B(n, 2h - 1) are studied. It is proven that the set of the minimum weight codewords of the bch-code B(n, 2m-2 - 1) equals the set of the minimum weight codewords of the punctured Reed-Muller code of length n and order 2, for any m. Several corollaries of this result are given.
New mathematical techniques for analysis of raw dumps of NAND flash memory were developed. These techniques are aimed at detecting, by analysis of the raw NAND flash dump only, the use of LFSR-based scrambling and the...
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New mathematical techniques for analysis of raw dumps of NAND flash memory were developed. These techniques are aimed at detecting, by analysis of the raw NAND flash dump only, the use of LFSR-based scrambling and the use of a binary cyclic code for error-correction. If detected, parameter values for both LFSR and cyclic error-correcting code are determined simultaneously. These can subsequently be applied to expose the content of memory pages in the raw NAND flash dump and prepare these for further processing with media analysis tools. The techniques were tested on raw NAND flash memory dumps of four different devices and in all cases LFSR-based scrambling and binary cyclic error-correcting codes were in use. (C) 2015 Elsevier Ltd. All rights reserved.
2-bit error correction for random errors in memory cells is of growing importance. Instead of the 1-bit error correcting and 2-bit error detecting Hsiao-code a 2-bit error correcting bch-code can be used with the disa...
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ISBN:
(纸本)9783031661457;9783031661464
2-bit error correction for random errors in memory cells is of growing importance. Instead of the 1-bit error correcting and 2-bit error detecting Hsiao-code a 2-bit error correcting bch-code can be used with the disadvantage that for the maximal code length of 2m(-1) the number of necessary check bits is 2 center dot m. Compared to the needed m check bits for the commonly implemented Hsiao-code the number of check bits is doubled and the necessary overhead for error correction is relatively high. To reduce this overhead it is of interest to determine 2-bit error correcting codes with maximal length for a given number of check bits. In this paper it is shown for the first time that the code length of a 2-bit error correcting bch-code cannot be enlarged by adding a further column to its H-matrix. (The proof is based on the fact that a 2-bit error correcting bchcode is quasi-perfect.) A similar result is also true for a 2-bit error correcting and 3-bit error detecting bch-code with included parity. For up to 8 check bits H-matrices for codes with maximal code length are determined. For larger numbers of check bits H-matrices with almost optimal code length are determined by a new algorithm of computer search, based on detailed properties of the columns of the corresponding H-matrices in there separated form.
We introduce a computer-based method for extending linear codes, which can be viewed as an inverse of the familiar construction Ii. As a result codes with record-breaking parameters are constructed.
We introduce a computer-based method for extending linear codes, which can be viewed as an inverse of the familiar construction Ii. As a result codes with record-breaking parameters are constructed.
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