DocumentCode :
3275413
Title :
A Suboptimal LQ Power Control Algorithm for a CDMA Wireless System
Author :
Campos-Delgado, D.U. ; Luna-Rivera, J.M. ; Martínez-López, F.J.
Author_Institution :
Zona Univ., San Luis Potosi
fYear :
2008
fDate :
March 31 2008-April 3 2008
Firstpage :
380
Lastpage :
385
Abstract :
In today´s wireless systems, power control is an important problem which is related to the quality-of-service (QoS) and battery utilization at the mobile units. This problem is studied in this work for the uplink of a direct-sequence code- division multiple-access communication (DS-CDMA) system. By a proper selection of the error function, the resulting linear decoupled feedback loops can be controlled efficiently following a distributed power control approach, and these closed-loops are independent of the user´s channel variations. A suboptimal LQ strategy is suggested and derived for power update. This control law has a variable structure that depends on the transmission roundtrip delay in the feedback system, which is a key parameter to establish closed-loop stability. It is demonstrated that in the limit of some synthesis parameters, the LQ-controller tends to a Dead-Beat response, improving the time response but sacrificing robustness. Meanwhile, the LQ-controller can be adjusted to increase its robustness. Simulation results are presented to compare the control algorithms using a standard single-step power correction approach.
Keywords :
closed loop systems; code division multiple access; delays; distributed control; feedback; linear quadratic control; linear systems; power control; quality of service; radio networks; stability; telecommunication control; variable structure systems; CDMA wireless system; QoS; battery utilization; closed-loop stability; direct-sequence code division multiple access communication system; distributed power control; error function; linear decoupled feedback loop; quality-of-service; suboptimal LQ control; transmission roundtrip delay; variable structure system; Batteries; Communication system control; Error correction; Feedback loop; Linear feedback control systems; Mobile communication; Multiaccess communication; Power control; Quality of service; Robustness;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Wireless Communications and Networking Conference, 2008. WCNC 2008. IEEE
Conference_Location :
Las Vegas, NV
ISSN :
1525-3511
Print_ISBN :
978-1-4244-1997-5
Type :
conf
DOI :
10.1109/WCNC.2008.72
Filename :
4489103
Link To Document :
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