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Performance Analysis of Semi-Coherent OFDM Systems With Imperfect Channel Estimates

This work presents the exact symbol error rate (SER) analysis of semi-coherent demodulated systems in the presence of imperfect knowledge of the channel estimates. The SER is derived in the context of orthogonal frequency division multiplexing (OFDM) systems where a modulation-hybrid frame structure is considered to enable blind channel estimation using a decision-directed approach. The exact SER is derived and presented in a closed-form analytical expression, which is then used to compute an accurate formula for the mean squared error (MSE) of the channel estimates. The obtained analytical and simulation results show that the SER and MSE are highly dependent on the channel correlation factor. However, reliable SER can still be obtained for most practical channel models, particularly when receiver diversity is incorporated.