Using Akebono satellite observations, we have examined the excitation mechanism of large-amplitude, electric and magnetic field variations in the vicinity of the cusp topside ionosphere. Three typical cusp events in the altitude range of ~2000 km, ~4000 km, and ~7500 km are investigated in detail. The phase-frequency relationship obtained from a wavelet analysis is compared with the theoretical one given by the Lysak 1991 model for each event to find the evidence for the existence of ionospheric Alfv¿n resonator (IAR). Also, the ratios of electric field to magnetic field variations are compared with theoretical values of inertial Alfv¿n waves to identify the existence of inertial Alfv¿n waves. The obtained results demonstrate the clear signature of the coexistence of IAR and inertial Alfv¿n waves in extended altitude range of the cusp topside ionosphere.