The objective of the present study is to find out the range of the IIHR layer radial position within which the plasma confinement in conventional L-mode regime may be improved. The recent ICRF-MC heating experiments on JET (RF power dominated D(3He)-discharges, PRF/(Ptot-PRF) 2.0) were analyzed. The RF power coupled into plasma in the ICRF-MC scenario improved confinement properties of discharges with respect to the (OH+NBI)-phase at the central locations of IIHR (|rii/apl| < 0.3) with the best result (up to ~60% improved confinement) closer to axis and at dipole antenna phasing. A shift of IIHR towards the plasma edge (|rii/apl| > 0.4) resulted in degradation of confinement. An analysis of plasma confinement based on plasma diamagnetic and thermal energy content, and results of modeling of the absorbed power at ICRF-MC are discussed.