ODQPSK non-coherent reception

This paper is concerned with a novel high performance non-coherent receiver structure for offset differential QPSK modulation. This structure accepts as input a complex baseband signal sampled at twice the transmission bit rate, evaluates the differential phase of this complex signal and performs simultaneous soft differential decoding, inter-symbol interference suppression and decision making. Employing a properly trained Viterbi algorithm, the proposed receiver structure achieves a 2 dB improvement on the SNR-BER curve over the ones of previously known structures and it approaches closely the performance of the coherent demodulation. This receiver structure is particularly attractive for TDMA wireless communications since it performs considerably better than π/4-DQPSK and it maintains the advantage of close-constant envelop. VLSI implementation issues and the role of the proposed structure on low power transceiver design are briefly discussed