Title :
Optimal space-time block codes for CDMA systems
Author :
Geng, Jifeng ; Mitra, Urbashi ; Fitz, Michael P.
Author_Institution :
Dept. of Electr. Eng., Ohio State Univ., Columbus, OH, USA
Abstract :
Space-time block codes have been well-addressed for single-user systems in recent works, the counterpart for CDMA systems will be discussed in this paper. A general system model is presented, the Chernoff bound for quasi-static channel is derived. Based on the Chernoff bound, performance criteria are obtained: diversity gain and coding grain. The coding gain is shown to be the same coding gain for a single-user system plus the effect of spreading, which essentially provides more coding gain than a narrowband system. Optimal 2-by-2 space-time block codes for the BPSK constellation are provided, and their performance as a function of correlation is investigated. It is observed that unitary codes do not necessarily achieve best performance. To this end, a non-unitary code for and BPSK constellation is supplied, which outperforms unitary codes for both spread and single-user systems. Performance analysis via numerical integration is discussed
Keywords :
block codes; code division multiple access; correlation methods; integration; multiuser channels; optimisation; phase shift keying; BPSK constellation; CDMA systems; Chernoff bound; coding grain; diversity gain; general system model; narrowband system; nonunitary code; numerical integration; optimal space-time block codes; performance; performance analysis; performance criteria; quasi-static channel; single-user system; single-user systems; spreading; unitary codes; AWGN; Base stations; Binary phase shift keying; Block codes; Diversity methods; Multiaccess communication; Narrowband; Quadrature phase shift keying; Receiving antennas; Transmitting antennas;
Conference_Titel :
MILCOM 2000. 21st Century Military Communications Conference Proceedings
Conference_Location :
Los Angeles, CA
Print_ISBN :
0-7803-6521-6
DOI :
10.1109/MILCOM.2000.904981
