The parametric excitation of ion-cyclotron waves by a lower-hybrid pump field is studied on the assumption that the magnitude of the pump is constant. The spatial amplification factor is given as a function of the wavenumber mismatch as produced by the plasma density gradient, and of the linear damping rates of the excited ion-cyclotron and sideband waves. The analysis is applied to plasma edge parameters relevant to the JFT2 heating experiment. It is found that ion-cyclotron harmonic modes are excited depending on pump frequency and plasma density. These modes are shown to have finite damping rates. The parallel refractive indices n_1z of the excited sideband fields are found to be always larger than that of the driven pump field. Transition to quasi-mode decay occurs either by decreasing the pump frequency or by increasing the applied RF-power.