Title :
Performance analysis for UCHT complex sequences in DS-CDMA downlink systems
Author :
Xie, Shoulie ; Rahardja, Susanto ; Gu, Zhenghui
Author_Institution :
Inst. for Infocomm Res., Singapore, Singapore
Abstract :
A performance analysis of orthogonal unified complex Hadamard transform (UCHT) spreading sequences in DS-CDMA downlinks is investigated in this paper. The coherent RAKE receiver is also adopted to reduce the effect of multipath fading. System performance is evaluated by means of signal-to-interference-plus-noise ratio (SINR) at the RAKE receiver. It is shown that the SINR of the system employing UCHT complex sequences is independent of the phase offsets between different paths, while the SINR of the system using Walsh-Hadamard (WH) sequences is related to the squared cosine of path phase offsets. As a result, the bit-error ratio (BER) performance of the DS-CDMA downlink system employing UCHT complex sequences is better than that of the system with WH sequences. Numerical simulations also demonstrate the benefits of the UCHT spreading sequences in the DS-CDMA downlinks with Rayleigh multipath fading.
Keywords :
Hadamard transforms; Rayleigh channels; code division multiple access; error statistics; mobile radio; multipath channels; radio receivers; spread spectrum communication; BER; DS-CDMA downlink; Rayleigh multipath fading; SINR; UCHT complex sequences; UCHT spreading sequences; Walsh-Hadamard sequences; bit-error ratio; coherent RAKE receiver; mobile communication systems; orthogonal unified complex Hadamard transform; path phase offset independence; signal-to-interference-plus-noise ratio; Bit error rate; Downlink; Fading; Multiaccess communication; Multipath channels; Numerical simulation; Performance analysis; Rayleigh channels; Signal to noise ratio; System performance;
Conference_Titel :
Vehicular Technology Conference, 2004. VTC2004-Fall. 2004 IEEE 60th
Print_ISBN :
0-7803-8521-7
DOI :
10.1109/VETECF.2004.1400103
