Noncoherent detection of digitally phasor block-modulated signals in the presence of DC offset

In this paper, we deal with noncoherent data detection of digitally phase modulated signals in the additive white Gaussian noise channel when a direct-current (DC) offset is present in the receiver baseband processing. By processing the received baseband signal block by block, a generalized linear transform is proposed to remove the offset prior to demodulation, thereby releasing the succeeding data detection process from the threat of DC offset. Operating on transform output blocks, a maximum-likelihood scheme is developed for noncoherently demodulating a phasor block modulated signal when the amplitude and carrier phase of the received signal are unknown. The block detection scheme is analytically shown to provide the bit error performance asymptotically approaching that of the corresponding ideal coherent phase-shift-keyed detection in the absence of DC offset when the block length is increased. An iterative detection scheme is also modified from the block detection scheme to simplify the realization complexity.