Fuzzy Control for Transmission Power Optimization in Cellular Phones

Abstract

In this paper is proposed a fuzzy control system for optimizing the transmission power in cellular phones. As the mobile station moves toward the edge of a cell, the cell's base station notes that the signal strength is diminishing. Meanwhile, the base station in the cell the mobile station is moving toward (which is listening and measuring signal strength on all frequencies, not just its own one) sees the phone's signal strength increasing. The two base stations coordinate with each other, and at some point, the phone gets a signal on a control channel telling it to change frequencies. This hand off switches the phone to a different cell, which receives the signal with a bigger intensity, so the next decrement of the transmission power will be the lower possible without risking the quality of the transmission. Nowadays the central cellular controls the transmission power on the mobile station, on intervals of 4 dbs to increase or decrease it, so the final power always is above or under the required power. The fuzzy control system proposed, basically controls the increment or decrement of the transmission power based on the measures of the signal intensity and the signal noise ratio, in this way the base station at a certain cell, will receive the radio frequency of the mobile station with the intensity required. This fuzzy system has two inputs, represented by the signal intensity and the signal noise ratio; and one output, change in the transmission power.