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   Vol.E87-B   No.8   pp.2212-2221
Publication Date: 2004/08/01
Online ISSN: 
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.