Title :
Spreading waveforms for multi-carrier CDMA systems
Author :
Popovic, Branislav M.
Author_Institution :
Ericsson Radio Syst. AB, Stockholm, Sweden
Abstract :
The paper contains an analysis of the basic criteria for the selection of spreading sequences for multi-carrier CDMA (MC-CDMA) systems with spectrum spreading in the frequency domain. It is shown that the time-domain crosscorrelation function between the spreading sequences is not a proper interference measure for the asynchronous MC-CDMA users. Therefore the spectral correlation function is introduced and, together with the crest factor and the dynamic range of the corresponding multicarrier waveforms, is used for the evaluation of MC-CDMA sequences. Some well-known classes of sequences, such as Walsh and Gold sequences, as well as orthogonal Gold and Zadoff-Chu (1972) sequences, are evaluated with respect to the aforementioned basic criteria. It is also shown that the multicarrier spread spectrum waveforms based on the multilevel Huffman sequences can have a lower crest factor than a single sine wave
Keywords :
AWGN channels; Huffman codes; code division multiple access; correlation methods; radiofrequency interference; sequences; spectral analysis; spread spectrum communication; AWGN channel; DS-CDMA; Gold sequences; MC-CDMA sequences; Walsh sequences; Zadoff-Chu sequences; asynchronous MC-CDMA; crest factor; dynamic range; frequency domain; interference measure; multi-carrier CDMA systems; multicarrier spread spectrum waveforms; multicarrier waveforms; multilevel Huffman sequences; multiple-access BPSK signaling; orthogonal Gold sequences; pair-wise interference probability density function; sine wave; spectral correlation function; spectrum spreading; spreading sequences; spreading waveforms; time-domain crosscorrelation function; Dynamic range; Frequency domain analysis; Gold; Multiaccess communication; Multicarrier code division multiple access; OFDM; Peak to average power ratio; Spread spectrum communication; Time domain analysis; Transmitters;
Conference_Titel :
Spread Spectrum Techniques and Applications, 1998. Proceedings., 1998 IEEE 5th International Symposium on
Conference_Location :
Sun City
Print_ISBN :
0-7803-4281-X
DOI :
10.1109/ISSSTA.1998.726227
