The ion-cyclotron resonance heating of monster sawtooth (period greater than the energy-confinement time) and pellet-fueled peaked-density profile in limiter discharges of JET tokamak are studied. The monster sawtooth is a characteristic JET regime which is related to fast ions generated during the minority ion heating. In this regime, the global energy confinement is improved by about. 20% over the sawteething discharges. In the ICRF heating of peaked-density profile discharges, we find typically that T,. is higher roughly by a factor of 2 and Te0 roughly by 35% at a fixed PToT/ne0 when compared to non-peaked profile cases. Also, on a similar comparison, the neutron production rate is found to be higher roughly by a factor of 4. Here, Te0 and Ti0 are central electron and ion temperatures respectively, ne0 is the central electron density and PToT is the total input power. The central confinement improves significantly whereas there is about 20% improvement in global electron kinetic-energy · confinement. The ion heating is improved in the pellet case, in part, due to a higher collisionality between the background ions and the energetic minority, but more significantly by a reduction of local ion-energy transport in the central region. Full ray-tracing calculations of power transferred to electrons and ions are consistent with the rate of rise of Te0 and Ti0 in peaked-profile cases. The transport-code simulation of these discharges reveals that there is a reduction of both ce and ci in. the central region of the plasma in the ICRF heated peaked-profile discharges where ce and ci are the electron and ion heat conductivities respectively. The improvement of confinement is not explained quantitatively by any of the existing hi-driven turbulence theories as the hi-parameter (hi = d ln T, I d ln n, where T, is the ion temperature and ni is the ion density) instead of dropping below the critical value remains above it for most of the duration of the improved confinement phase. Understanding of the physical mechanism(s) that play a role in this improvement is not yet clear.