From its beginning, transmit power has always placed a significant constraint on the performance of wireless radio systems. The transmit power control problem can be characterized as that of maintaining adequate power in each transmitted waveform so as to increase the expectation that the minimum required SIR at the receiver will at least be reached. This has been shown not to be a trivial endeavor due to the variability of the physical channel with time as well as interference and other practical constraints on “infinitely” increasing transmit power. Several power control algorithms have been proposed, of which the class of distributed and autonomous transmit power control algorithms have been shown in literature to perform quite satisfactorily when compared to centralized schemes due to the moderate complexity that is achievable; and the vast control and signaling overhead that is saved. This thesis work explores the application of fuzzy control to the subject of modeling uplink transmit power control in code division multiple access system. A possible implementation scenario of an SIR-based fully distributed constrained transmit power control algorithm in a multiservice network by applying fuzzy proportional-plus-integral control with a two-input (error and error change) and one-output (transmit power adjustment command) fuzzy rule base and inference engine is proposed.

Detta examensarbete går djupare in på tillämpningar av Fuzzy Control inom modellering av upplänk sändareffektreglering i Code Division Multiple Access (CDMA)-system. Efter en genomgång av effektregleringsalgoritmer i litteraturen, presenteras ett möjligt implementationsscenario för en SIR-baserad, fullt distribuerad, effektregleringsalgoritm i ett multiservice nätverk. En fuzzy proportionell-plus-integrerande regulator med två ingångar (fel samt felförändringen) samt en utgång (effektregleringsanpassning) med ingående fuzzy regelsystem samt inferensmotor skissas därefter upp. Slutsatserna indikerar att fuzzy effektreglering är förhållandevis effektiv samt ger bra resultat för att möta de effektregleringskrav som ställs i ett CDMA-nätverk.