Title :
Adaptive discrete stochastic approximation algorithms for spreading code optimization in DS/CDMA
Author :
Krishnamurthy, Vikram ; Wang, Xiaodong ; Yin, George
Author_Institution :
Dept. of Electr. Eng., British Columbia Univ., Vancouver, BC, Canada
Abstract :
The aim of this paper is to present discrete stochastic approximation algorithms that adaptively optimize the spreading codes of users in a CDMA system employing linear MMSE receivers. The proposed algorithm is able to adapt to slowly time-varying channel conditions. One of the most important properties of the algorithm is its self-learning capability - it spends most of the computational effort at the global optimizer of the objective function. A tracking analysis of the adaptive algorithms is presented together with mean square convergence. An adaptive-step-size algorithm is also presented for optimally adjusting the step size based on the observations.
Keywords :
adaptive codes; channel coding; code division multiple access; discrete time systems; least mean squares methods; optimisation; radio receivers; radio tracking; spread spectrum communication; stochastic processes; stochastic systems; time-varying channels; unsupervised learning; DS-CDMA; adaptive discrete stochastic approximation algorithms; adaptive step size algorithm; code division multiple access; linear MMSE receivers; linear minimum mean squared error receivers; mean square convergence; observations; self learning capability; spreading code optimization; step size adjustment; time varying channel; tracking analysis; Adaptive algorithm; Algorithm design and analysis; Approximation algorithms; Convergence; Fading; Filtering algorithms; Multiaccess communication; Stochastic processes; Stochastic systems; Transmitters;
Conference_Titel :
Decision and Control, 2003. Proceedings. 42nd IEEE Conference on
Print_ISBN :
0-7803-7924-1
DOI :
10.1109/CDC.2003.1272540
