Cyclic Shifted-and-Extended Codes Based on a Quasi-Orthogonal Sequence for a CDM Transmission Scheme

Kazuyuki SHIMEZAWA  Hiroshi HARADA  Hiroshi SHIRAI  

IEICE TRANSACTIONS on Communications   Vol.E89-B   No.11   pp.2998-3007
Publication Date: 2006/11/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.11.2998
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Transmission Systems and Transmission Equipment for Communications
zero cross-correlation,  Quasi-Orthogonal sequence,  Rake combining,  cyclic shifted-and-extended codes,  code division multiplexing,  

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We have developed a code-division-multiplexing (CDM) transmission scheme for future road-vehicle communication systems, which uses cyclic shifted-and-extended (CSE) codes generated from a basic code with superior auto-correlation characteristics. This paper proposes to use a Quasi-Orthogonal (QO) sequence as the basic code. Its auto-correlation values are zero except at zero and middle shifts. When the CDM transmission is performed by the CSE codes based on the QO sequence, a desired correlation value is, at a receiver, interfered by the auto-correlation value at middle shift. Therefore, an elimination technique for the interfered correlation value is proposed and realizes zero cross-correlation characteristics within the cyclical shift interval. The new CDM transmission scheme based on the proposed scheme is evaluated by computer simulations in terms of the bit-error-rate performance.