https://scholars.lib.ntu.edu.tw/handle/123456789/347538
標題: | Trellis ternary line coding scheme for asynchronous optical CDMA systems | 作者: | Liu, M.-Y. HEN-WAI TSAO JOE-AIR JIANG |
關鍵字: | Equal-weight orthogonal; Optical CDMA; Prime codes; Trellis ternary line coding | 公開日期: | 2009 | 卷: | 120 | 期: | 15 | 起(迄)頁: | 765 - 772 | 來源出版物: | Optik | 摘要: | In this paper, we investigate the employment of a ternary line coding technique based on Ungerboeck's trellis-coded method in asynchronous optical CDMA systems. The ternary coding we use is predicated upon the equal-weight orthogonal (EWO) scheme. Each user transmits two mutually orthogonal signature sequences to represent "+1" and "-1", respectively, and nothing is transmitted for "0". The receiver employs a maximum-likelihood soft-decoder to select the path with minimum Euclidean distance as the preferred path. This trellis ternary coding scheme applies set partitioning with partially overlapping subsets to increase the free Euclidean distance, which considerably improves system performance. Furthermore, due to line coding technique, such scheme comprises sufficient clock information, and thus benefits for baseband timing extraction (i.e. clock recovery). Numerical results reveal that the proposed trellis ternary coding scheme can significantly reduce the error floor and allow more active users to be accommodated in the network. © 2008 Elsevier GmbH. All rights reserved. |
URI: | http://www.scopus.com/inward/record.url?eid=2-s2.0-70349259374&partnerID=MN8TOARS http://scholars.lib.ntu.edu.tw/handle/123456789/347538 |
ISSN: | 00304026 | DOI: | 10.1016/j.ijleo.2008.03.007 | SDG/關鍵字: | Base bands; Clock recovery; Coded method; Coding scheme; Coding techniques; Equal-weight orthogonal; Error floor; Euclidean distance; Numerical results; Optical CDMA; Orthogonal signatures; Prime codes; Set partitioning; Trellis ternary line coding; Ungerboeck; Maximum likelihood; Code division multiple access |
顯示於: | 電機工程學系 |
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