
TrellisDecoder |
ptolemy.actor.lib.comm.TrellisDecoder |
The TrellisDecoder is a generalization of the ViterbiDecoder. It
can handle trellis coding, which has non-antipodal constellation.
For a <i>k</i>/<i>n</i> convolutional code, the constellation
should map each codeword into a complex number. Hence the length
of the constellation should be a complex array of length
2<i><sup>n</sup></i>. For example, a 1/2 rate convolutional code
should use 4PSK. a <i>k</i>/3 convolutional code should use 8PSK.
<p>
The input port of the TrellisDecoder is complex. On each firing,
the TrellisDecoder reads one input. The Euclidean distance is defined
as the distance between the noisy input and the point in the
constellation mapped from the codeword. Like in ViterbiDecoder,
this actor produces <i>k</i> outputs on each firing.
<p>
See ConvolutionalCoder and ViterbiDecoder for details about
the meaning of these parameters.
<p>
For more information on convolutional codes, Viterbi decoder, and
trellis coding, see the ConvolutionalCoder actor, ViterbiDecoder
actor and Proakis, <i>Digital Communications</i>, Fourth Edition,
McGraw-Hill, 2001, pp. 471-477 and pp. 482-485,
or Barry, Lee and Messerschmitt, <i>Digital Communication</i>, Third Edition,
Kluwer, 2004.
<p>
Author(s): Ye Zhou, contributor: Edward A. Lee
Version:$Id: TrellisDecoder.doc.html,v 1.1 2006/02/22 18:42:26 mangal Exp $
Pt.Proposed Rating:Yellow (eal)
Pt.Accepted Rating:Red (cxh)