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A New CDM Transmission Scheme with Cyclic Shifted-and- Extended Codes and a Cancellation Technique for Accumulated Cross-Correlation Values
Kazuyuki SHIMEZAWA Hiroshi HARADA Hiroshi SHIRAI
IEICE TRANSACTIONS on Communications
Publication Date: 2004/08/01
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
cross-correlation cancellation, cyclic shifted-and-extended codes, code division multiplexing, mobile radio communication,
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We have developed a code-division-multiplexing (CDM) transmission scheme for future cellular communication systems, which uses cyclic shifted-and-extended (CSE) codes generated from an M-sequence to enable seamless communication in highly mobile environments. Because the correlation characteristics of CSE codes are determined by the M-sequence, the cross-correlation values are accumulated as a result of combining transmitted signals with opposite polarities in parallel channels. The accumulated cross-correlation values significantly degrade transmission performance, especially with multi-level modulation schemes such as quadrature amplitude modulation (QAM). We thus propose a cancellation technique to eliminate the accumulated cross-correlation values. We have evaluated the transmission performance of the CDM transmission scheme with the proposed technique by computer simulation. The new scheme enables high-quality data transmission in fast-fading channels.