Title :
UCHT complex sequences for downlink multi-carrier DS-CDMA systems
Author :
Gu, Zhenghui ; Xie, Shoulie ; Rahardja, Susanto
Author_Institution :
Inst. for Infocomm Res., Singapore, Singapore
fDate :
30 May-1 June 2005
Abstract :
Downlink multi-carrier direct sequence code-division multiple-access (MC-DS-CDMA) often makes use of Walsh-Hadamard (WH) sequences to channelize different users and increase diversity gain. The recently introduced unified complex Hadamard transform (UCHT) sequences are, for the first time, applied as spreading sequences in MC-DS-CDMA. The quadri-phase UCHT complex sequences are orthogonal and easy to generate. Some of UCHT sequences provide better autocorrelation properties than orthogonal WH sequences. It is found that the system spread by UCHT sequences outperforms that spread by WH sequences in frequency selective fading channels.
Keywords :
Hadamard transforms; code division multiple access; fading channels; sequences; spread spectrum communication; MC-CDMA; Walsh-Hadamard sequences; autocorrelation; diversity gain; downlink multi-carrier DS-CDMA systems; frequency selective fading channels; multi-carrier direct sequence code-division multiple-access; quadri-phase complex sequences; spreading sequences; unified complex Hadamard transform sequences; Autocorrelation; Bit error rate; Diversity methods; Downlink; Fading; Frequency conversion; Frequency division multiplexing; Interference; Multiaccess communication; Multicarrier code division multiple access;
Conference_Titel :
Vehicular Technology Conference, 2005. VTC 2005-Spring. 2005 IEEE 61st
Print_ISBN :
0-7803-8887-9
DOI :
10.1109/VETECS.2005.1543318
