Trellis Coded Modulation for High Bit Rate Digital Subscriber LoopsThomas D. Bilodeau (supervisor: Dr. Witold A. Krzymien)
MSc Thesis, University of Alberta, Department of Electrical Engineering, April 1990
This thesis has analyzed different transceiver structures for the proposed high-bit-rate (800 kb/s) digital subscriber loop interface which would operate on loops in the carrier serving area (CSA). The investigation has included examining the possibilities of increasing the transmission rate on these metallic loops through the use of trellis coded modulation and improved equalization algorithms. The actual analysis was accomplished through a simulation study which included models of the subscriber loops, the various transceivers and a number of noise sources.
We have compared the achievable bit rates of transceivers using 8 PAM, 16 QAM and 32 QAM signalling combined with optimal four and eight state trellis codes to the achievable bit rates of transceivers using uncoded 4 PAM, 8 AMPM and 16 QAM, respectively. These comparisons were also done with a variety of different equalizer structures. From our results, we have found that by using both a forward T/2 fractionally spaced linear equalizer and a decision feedback equalizer together, system performance can be dramatically improved over using either equalizer separately. We have also found that the uncoded 4 PAM and coded 8 PAM baseband transceivers have the best performances compared to the other uncoded and coded passband transceivers, respectively. Since the passband transceivers are considerably more complicated, the baseband transceivers are clearly the preferred transceivers to provide digital transmission over subscriber loops. However, it is only with trellis encoding that these transceivers can achieve the performance which is necessary to ensure the ubiquitous deployment of the high-bit-rate access (800 kb/s) in the carrier serving area.
CONTACTS: Tom Bilodeau, Witold A. Krzymien
SUBJECTS: Error Control Coding
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