PAPR Comparison between MC-CDMA Systems With and Without Long Code

A. Okuda, M. Saito, T. Hara, M. Okada, and H. Yamamoto (Japan)

Keywords

CDMA Systems, OFDM Technology, Spread Spec trum Techniques, Multi-Carrier CDMA Systems, Peak-to Average Power Ratio, Spreading Sequences

Abstract

The Peak-to-Average Power Ratio (PAPR) of Multi-Carrier (MC)-CDMA system down-link is analysed for the sys tems using both short and long code and those using only short code. Hadamard sequence provides the best PAPR performances compared with orthogonalized M-sequence, orthogonal Gold sequence, and Golay complementary se quence for larger than 50 % load factor when only short code is employed. It can be obtained that the long code doesn't change the distribution of PAPR values of mul tiuser MC-CDMA system down-link signals except for Hadamard sequence. Moreover, we propose PAPR re duction method for the down-link of MC-CDMA systems in this paper. Avoiding use of specific combination of Hadamard sequences reduces the maximum PAPR by ap proximately 2 dB compared with normal sequence assign ment of spreading sequences.

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