Title :
Adaptive optimization of binary/quaternary CDMA signatures in multipath fading environments
Author :
Grover, Rohan ; Pados, Dimitris A. ; Medley, Michael J.
Author_Institution :
Dept. of Electr. Eng., State Univ. of New York, Buffalo, NY
Abstract :
We develop a new algorithm to optimize adaptively binary and quaternary signatures for code-division multiple-access (CDMA) communications over multipath channels and/or asynchronous channel access. Using the observed signal autocorrelation matrix, the algorithm attempts to maximize over the binary or quaternary antipodal sequence field the signal-to-interference-plus-noise ratio (SINR) at the output of the maximum SINR linear filter. While this maximization problem is NP-hard, the algorithm is seen to produce in short polynomial time highly desirable solutions that approach in performance the theory-only complex/real-field optimal signature vectors. Signature adaptation may be carried out in either a single or a multi-user mode. Simulation studies included herein offer direct performance comparisons with other known binary signature set designs and the theoretical complex/real-valued optimal vectors
Keywords :
binary sequences; code division multiple access; fading channels; multipath channels; optimisation; NP-hard problem; SINR; adaptive optimization; asynchronous channel access; binary CDMA signatures; binary antipodal sequence; binary signature set; code-division multiple-access; linear filter; maximization problem; multipath channels; multipath fading environments; optimal signature vectors; quaternary CDMA signatures; quaternary antipodal sequence; signal autocorrelation matrix; signal-to-interference-plus-noise ratio; Autocorrelation; Fading; Filters; Frequency; Laboratories; Multiaccess communication; Multipath channels; RAKE receivers; Signal processing; Signal to noise ratio; Binary sequences; Cholesky decomposition; code-division multiple-access (CDMA); code-division multiplexing; quaternary sequences; signal-to-interference-plus-noise ratio (SINR); signature sets; spread-spectrum communications;
Conference_Titel :
Military Communications Conference, 2005. MILCOM 2005. IEEE
Conference_Location :
Atlantic City, NJ
Print_ISBN :
0-7803-9393-7
DOI :
10.1109/MILCOM.2005.1605799