Expanded Trellis Designs for Noncoherent Communications with Frequency Offset

In this letter, we propose a noncoherent communication system that can be used in the communication environment in which the frequency estimation is only roughly obtained and the phase synchronization is not employed. The transmitter side has the serial turbo coding structure composed of a convolutional encoder followed by an interleaver, an MPSK signal mapper and a differential modulator. At the receiver side an expanded trellis is employed to represent not only the possible paths of the differentially encoded MPSK but also the paths resultant from the possible phase variations due to the frequency offset and the phase noise.