Title :
Coding across multicodes and time in CDMA systems for dispersive channels
Author :
Park, J. ; Lim, J.-H. ; Gelfand, S.B.
Author_Institution :
Sch. of Electr. & Comput. Eng., Purdue Univ., West Lafayette, IN, USA
Abstract :
When combining a multicode CDMA system with convolutional coding, two methods have been considered in the literature. In one method, coding is across time in each multicode channel while in the other the coding is across both multicodes and time. In this paper, a performance/complexity analysis of decoding metrics and trellis structures for the two schemes is carried out. It is shown that the latter scheme can exploit the multicode diversity inherent in convolutionally coded direct sequence code division multiple access (DS-CDMA) systems which employ minimum squared error (MMSE) multiuser detectors. In particular, when the MMSE detector provides sufficiently different signal-to-reference ratios (SIRs) for the multicode channels, coding across multicodes and time can obtain significant performance gain over across time, with nearly the same decoding complexity.
Keywords :
channel coding; code division multiple access; computational complexity; convolutional codes; dispersive channels; least mean squares methods; multiuser detection; spread spectrum communication; DS-CDMA; MMSE; complexity analysis; convolutional code; decoding metrics; direct sequence code division multiple access; dispersive channels; minimum mean squared error; multicode CDMA system; multicode diversity; multiuser detector; performance analysis; signal-to-interference ratio; trellis structures; Convolution; Convolutional codes; Decoding; Detectors; Direct-sequence code-division multiple access; Dispersion; Diversity reception; Multiaccess communication; Performance analysis; Performance gain;
Conference_Titel :
Wireless Communications and Networking, 2003. WCNC 2003. 2003 IEEE
Conference_Location :
New Orleans, LA, USA
Print_ISBN :
0-7803-7700-1
DOI :
10.1109/WCNC.2003.1200364
