Title :
Optimal QPSK modulated quasi-orthogonal functions for IS-2000
Author :
Shanbhag, Abhijit G. ; Holtzman, Jack
Author_Institution :
Morphics Technol. Inc., Campbell, CA, USA
Abstract :
The forward link (FL) of a 3G CDMA system may be Walsh code limited in certain scenarios. Thus, other sets of orthogonal sequences, quasi-orthogonal functions (QOFs), which have low correlation with the original Walsh sequences are needed. A method of generating QOFs by multiplying each Walsh code by a vector of BPSK symbols, selected based on certain correlation criteria, was proposed by K. Yang et al. (see IEEE Trans. Info. Theory, 2000). In this paper, a method is provided for constructing vectors of QPSK symbols such that the QOFs have optimal mini-max correlation with Walsh code sets of variable length. This approach of using optimal QPSK-modulated QOFs has been adopted in IS-2000 standards
Keywords :
Walsh functions; code division multiple access; correlation methods; land mobile radio; minimax techniques; multiuser channels; quadrature phase shift keying; radio links; sequences; spread spectrum communication; telecommunication standards; variable length codes; 3G CDMA system; BPSK symbols; IS-2000 standards; IS-95; QPSK symbols; TIA/EIA-95 CDMA standard; Walsh code; Walsh functions; Walsh sequences; correlation; forward link; optimal QPSK modulated quasi-orthogonal functions; optimal QPSK-modulated QOF; optimal mini-max correlation; orthogonal sequences; p; variable length codes; vectors construction; Binary phase shift keying; Lifting equipment; Multiaccess communication; Proposals; Quadrature phase shift keying; Spread spectrum communication; Tree data structures;
Conference_Titel :
Spread Spectrum Techniques and Applications, 2000 IEEE Sixth International Symposium on
Conference_Location :
Parsippany, NJ
Print_ISBN :
0-7803-6560-7
DOI :
10.1109/ISSSTA.2000.876536
