Chip Interleaved Multicode DS-CDMA with MMSEC in A Fading Channel

Takeshi ITAGAKI  Tomoki SAO  Deepshikha GARG  Fumiyuki ADACHI  

IEICE TRANSACTIONS on Communications   Vol.E87-B   No.1   pp.79-87
Publication Date: 2004/01/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
multicode DS-CDMA,  chip interleaving,  MMSEC,  fading channel,  

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Direct sequence code division multiple access (DS-CDMA) provides flexible data transmission in wide range of data rates by the use of orthogonal multicode multiplexing. In a multipath fading environment, the transmission performance of multicode DS-CDMA degrades as that of single code DS-CDMA does. Chip interleaving is known to improve the bit error rate (BER) performance of the single code transmission by altering the fading channel into severely time selective fading channel. However, this partially destroys orthogonality property among spreading codes and thus, significantly degrades the BER performance of multicode DS-CDMA. In this paper, we propose the joint use of chip interleaving and time-domain minimum mean square error combining (MMSEC) equalization to improve the multicode DS-CDMA transmission performance. It is confirmed by computer simulations that the joint use of chip interleaving and MMSEC equalization significantly improves the BER performance of multicode DS-CDMA and achieves better BER performance compared to the single code DS-CDMA using chip interleaving and maximal ratio combining (MRC).