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, MultiCarrier CDMA Systems, Peakto 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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