Title :
Implementation of transmit antenna weight adaptation through stochastic gradient feedback
Author :
Banister, Brian C. ; Zeidler, James R.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of California, San Diego, CA, USA
Abstract :
Feedback assisted transmission antenna weight adaptation has been proposed for Third Generation cellular systems to provide increased capacity on the forward link. This approach provides enhancement concurrently from fading mitigation and beam steering. One such algorithm maximizes the usable power to the mobile by perturbation extracted gradient adaptation of the transmit weight vector. With perfect channel estimation and other idealized assumptions this method has been shown to be capable of providing weights approaching that of the optimal multi-element transmitter. In this paper a method for common perturbation transmission is introduced and compared to dedicated perturbation transmission in a CDMA system. In addition, a subspace weighting approach is introduced to enhance the algorithm performance in correlated fading. Simulations of the algorithm operating in a cdma2000 system incorporate feedback bit errors, latency and channel estimation errors with a dedicated pilot.
Keywords :
Rayleigh channels; adaptive antenna arrays; cellular radio; code division multiple access; correlation methods; feedback; gradient methods; multiuser channels; stochastic processes; transmitting antennas; 3G cellular systems; CDMA system; algorithm performance; beam steering; cdma2000 system; channel estimation errors; common perturbation transmission; correlated fading; dedicated perturbation transmission; dedicated pilot; fading mitigation; feedback assisted weight adaptation; feedback bit errors; flat Raleigh fading channel; forward link capacity; latency; optimal multi-element transmitter; perfect channel estimation; perturbation extracted gradient adaptation; simulations; stochastic gradient algorithm; stochastic gradient feedback; subspace weighting; third generation cellular systems; transmit antenna weight adaptation; transmit weight vector; Adaptive arrays; Antenna feeds; Beam steering; Channel estimation; Delay; Fading; Feedback; Multiaccess communication; Transmitters; Transmitting antennas;
Conference_Titel :
Signals, Systems and Computers, 2001. Conference Record of the Thirty-Fifth Asilomar Conference on
Conference_Location :
Pacific Grove, CA, USA
Print_ISBN :
0-7803-7147-X
DOI :
10.1109/ACSSC.2001.987741