| dc.description.abstract | In this dissertation, firstly, we propose a novel bandwidth-efficient noncoherent trelliscoded
MPSK scheme, in which a particularly-designed differential encoder is added in
front of the trellis encoder. With this differential encoder, trellis-coded MPSK proposed
by Ungerboeck is no longer noncoherently catastrophic and thus achieves better error
performance. Moreover, new trellis codes which, for the proposed scheme, have better bit
error rates than Ungerboeck’s codes are found by computer searches.
Secondly, we propose a general noncoherently non-catastrophic trellis-coded modulation
scheme, in which the transmitter includes a differential encoder, a rotator, an inverse
signal mapper, a convolutional encoder and a signal mapper. We present examples of
the proposed scheme including MPSK (M-ary phase shift keying), QAM (quadratureamplitude
modulation), and TAPSK (twisted amplitude and phase shift keying). For
trellis-coded QAM, a differential encoder with which the complexity of the proposed
scheme can be reduced is proposed. We also modify the proposed two-dimensional trelliscoded
modulation to be multi-dimensional noncoherently non-catastrophic trellis-coded
modulation. Simulation results demonstrate that for noncoherent decoding, the proposed
trellis-coded QAM has much better error performance than conventional trellis-coded
QAM, and the proposed trellis-coded 16APSK outperforms trellis-coded 16QAM for short
observation length.
We use the simplest algorithm, called BDFA, in the receiver side. In 8PSK constellation,
the simulation results are better than Ungerboeck’s scheme. The advantage of
our scheme decreases when the size of constellation increases. Therefore, we use algoi
rithm to modify the specific differential decoder to improve the BER of our proposed
scheme. Finally, a combined trellis decoder is proposed. This decoder improves the BER
performance, further.
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