排序方式: 共有70条查询结果,搜索用时 15 毫秒
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Based on Galois Field (GF(q)) multiplicative group, a new coding scheme for Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) codes is proposed, and the new coding scheme has some advantages such as the simpler construction, the easier implementation encoding, the lower complexity of the encoding and decoding, the more flexible adjustment of the code length as well as the code rate and so forth. Under the condition of considering the characteristics of optical transmission systems, an irregular QC-LDPC (3843,3603) code to be suitable for optical transmission systems is constructed by applying the proposed new coding scheme. The simulation result shows that the net coding gain (NCG) of the irregular QC-LDPC (3843,3603) code is respectively improved 2.14 dB, 1.19 dB, 0.24 dB and 0.14 dB more than those of the classic RS (255,239) code in ITU-T G.975, the LDPC (32640,30592) code in ITU-T G.975.1, the regular SCG-LDPC (3969,3720) code constructed by the Systematically Constructed Gallager (SCG) coding scheme and the regular QC-LDPC (4221,3956) code at the bit error rate (BER) of 10-8. Furthermore, all the five codes have the same code rate of 93.7%. Therefore, the irregular QC-LDPC (3843,3603) code constructed by the proposed new coding scheme has the more excellent error-correction performance and can be better suitable for optical transmission systems. 相似文献
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Aaron Potechin 《Designs, Codes and Cryptography》2008,46(3):243-259
We show that there are no complete 44-caps in AG(5, 3). We then use this result to prove that the maximal size for a cap in
AG(6, 3) is equal to 112, and that the 112-caps in AG(6, 3) are unique up to affine equivalence.
相似文献
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在研究容错图像编码算法的基础上,针对图像压缩编码中复杂度较大和将图像分成多个小块而带来的图像重建中有分块痕迹等问题,在子带位平面编码(SBC)算法中加入了与图像无关的率失真优化编码并采用虚拟分块的方法,对SBC算法进行了改进,实验结果表明,在相同压缩倍数和相同误码率情况下,本算法与传统的图像压缩算法重建图像的峰值信噪比提高了1.0~1.5dB。 相似文献
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Bram van Asch Henk Hollmann Henk van Tilborg 《Journal of Combinatorial Theory, Series A》2006,113(8):1594-1613
When Jack van Lint was appointed as full professor at the Eindhoven University of Technology at the age of 26 he combined a PhD in number theory with a very open scientific mind. It took a sabbatical visit to Bell Laboratories in 1966 to make him understand that a new and fascinating field of applied mathematics was emerging: discrete mathematics. It fascinated and inspired him for the rest of his life. When he passed away on September 28, 2004, he left behind a legacy of 18 books and 177 articles, covering many aspects of coding theory, combinatorics, and finite geometry.van Lint was also a strong international advocate of the role that discrete mathematics ought to play in modern applied mathematics curricula. Quite a few departments sought his advice. Years later, four different universities showed their appreciation by awarding him an honorary degree.This overview is an homage to van Lint's academic achievements and can serve as an introduction to his work for younger generations. 相似文献
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设计了一款采用波前编码技术的虹膜采集光学系统,以实现大景深、自然非约束状态下的成像.以传统的光学系统评价指标斯特利尔比和能量集中度作为波前编码系统的成像特征,利用ZEMAX软件对波前编码系统进行设计,权衡了离焦不敏感性和图像可恢复性.比较了带有立方相位编码板和带有修正项的立方相位编码板的虹膜采集系统以及传统系统的焦深延拓效果.发现采用立方相位编码板的虹膜采集光学系统的焦深延拓效果最佳,其焦深是传统系统的8倍.该系统增大了虹膜采集的距离,对于自然状态虹膜成像系统设计有一定的参考价值. 相似文献
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非线性等重码的一个上界 总被引:3,自引:0,他引:3
本文给出等重码的一个上界,并且举例说明这个上界是可以达到的,作为直接推论,我们推导出等重等距码的几个结果。 相似文献
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Pierre A. von Kaenel 《Fuzzy Sets and Systems》1982,8(2):199-204
A fuzzy code is defined as a fuzzy subset of n-tuples over a set F. An analysis of the Hamming distance between two fuzzy codewords and the error-correcting capability of a regular code in terms of its corresponding fuzzy code is presented. 相似文献
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Anton Skidin Alexey Redyuk Olga Shtyrina Michael Fedoruk Alex Shafarenko 《Optics Communications》2011,284(19):4695-4698
We quantify the error statistics and patterning effects in a 5 × 40 Gbit/s WDM RZ-OOK SMF/DCF fibre link using hybrid Raman/EDFA amplification. By extensive use of a numerical model, we determine how the error statistics change with the transmission distance. This knowledge is used as a basis for a constrained coding technique in order to improve the transmission error rate. We propose an adaptive constrained code for mitigation of the patterning effects and demonstrate that this approach can substantially reduce the bit error rate (BER) even for very large values of the channel BER (BER > 10− 1). The proposed technique can be used in combination with forward error correction schemes (FEC) to extend the range of channel BERs that an FEC scheme is effective over. 相似文献