For the first time, a partial response fading channel is introduced. The new channel model acts in a similar way to partial response signalling (PRS) with a Rayleigh probability density function. Emphasis is given to jitter and error performances of IM-PSK schemes in the proposed channel with ideal channel state information, but with no Side information existing on the phase noise process. Analytical upper bounds are derived using the Chernoff bounding technique, combined with the modified generating functional approach. Simulation studies confirming analytically obtained curves are carried out.