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We present an effective method for time domain channel estimation of wireless orthogonal frequency division multiplexing (OFDM) system. Relying on a bent-pipe mechanism, the mobile receiver sends a fraction of the received data back to the base station which can then estimate both the forward link and reserve link channel impulse responses. Given knowledge on the forward link channel response, the resource rich base station can employ effective adaptive modulation schemes to increase OFDM system capacity. In this paper, closed-form expressions for channel estimation Cramer Rao lower bound are derived for the feedback system. Impact of feedback parameters on channel estimation performance is discussed through Cramer Rao bound analysis and simulation. Identifiability issues associated with power loaded multicarrier systems are also addressed. Simulation results on the proposed feedback channel estimation scheme are shown.