Effects of Estimation Errors on the Noncoherent Capacity Over Time-Varying Channels

We investigate the channel capacity of noncoherent communications over fiat fading channels. The lower bound of the noncoherent channel capacity as well as the upper bound of the capacity penalty using noncoherent communications are characterized and contrasted with the coherent capacity. Analytical results show that the coherent channel capacity is achievable via noncoherent communications under certain signal to noise ratios (SNRs) and Doppler frequency shifts. The thresholds of SNRs and Doppler frequency shifts are provided, under which noncoherent communications can perform virtually at no capacity penalty.