An exemplary method for treating sleep apnea is described that includes determining parameters for a cardiac pacing pulse based, at least in part, on information characteristic of sleep apnea, wherein the cardiac pacing pulse aims to create a hemodynamic imbalance. The wireless device transmits first uplink signals in the second carrier group employing a first additional carrier in the second carrier group as a timing reference carrier. When the harmonics are detected, it is determined that the large reflection wave exceeding the dynamic range of the AD converter has been inputted, and a lost input amplitude is corrected in accordance with a correction table showing a relation between the harmonic order and an input amplitude correction amount which have previously been recorded.