Title :
Crest factors of Shapiro-Rudin sequence based multi-code MC-CDMA signals
Author :
Choi, Byoung-Jo ; Tellambura, Chintha ; Hanzo, Lajos
Author_Institution :
Dept. of Electron. & Comput. Sci., Southampton Univ., UK
fDate :
6/24/1905 12:00:00 AM
Abstract :
The envelope power of MC-CDMA signals usually exhibits wide fluctuations, leading to a high value of the associated crest factor. However, when Shapiro-Rudin based sequences, namely a Shapiro-Rudin (1959) pair, a Shapiro-Rudin based sub-complementary pair and a Shapiro-Rudin based Sivaswamy´s (1978) complementary set are used for two- and four-code BPSK modulated MC-CDMA spreading sequences, the crest factor is found to be bounded by 3dB. These sequences belong to the so-called orthogonal complementary set and Walsh-Hadamard sequences constitute a special case of these sets, when the sequence length is equal to the number of codes. When a typical nonlinear power amplifier is used, the low crest factor of the Shapiro-Rudin sequence based multi-code MC-CDMA scheme results in reduced amplifier-induced signal clipping. Hence a reduced power loss is imposed due to clipping in comparison to OFDM and to multicode MC-CDMA schemes based on other spreading sequences, such as Walsh codes, orthogonal Gold codes, Frank (1962) codes and Zadoff-Chu (1972) codes.
Keywords :
code division multiple access; modulation coding; multiuser channels; phase shift keying; power amplifiers; sequences; spread spectrum communication; BPSK modulated MC-CDMA spreading sequence; Frank codes; OFDM; Shapiro-Rudin based Sivaswamy´s complementary set; Shapiro-Rudin based sub-complementary pair; Shapiro-Rudin pair; Shapiro-Rudin sequence; Walsh codes; Walsh-Hadamard sequences; Zadoff-Chu codes; coded modulation; crest factors; envelope power; four-code BPSK; multi-code MC-CDMA signals; nonlinear power amplifier; orthogonal Gold codes; orthogonal complementary set; reduced power loss; sequence length; spreading sequences; two-code BPSK; Binary phase shift keying; Fading; Fluctuations; Frequency diversity; Gold; Multiaccess communication; Multicarrier code division multiple access; Multipath channels; OFDM; Power system modeling;
Conference_Titel :
Vehicular Technology Conference, 2002. VTC Spring 2002. IEEE 55th
Print_ISBN :
0-7803-7484-3
DOI :
10.1109/VTC.2002.1002861
