DSP implementation of trellis coded modulation and distributed space time coding



Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Lane Department of Computer Science and Electrical Engineering

Committee Chair

Matthew C. Valenti.


Trellis coded modulation (TCM) combines convolutional coding with modulation, and offers approximately 2--3 dB of coding gain without requiring a corresponding bandwidth expansion. This thesis describes the process of encoding TCM, convolutional codes, decoding using the Viterbi Algorithm (VA), M-ary modulation formats suitable for TCM, and the evaluation of TCM performance.;The concept of multiple TCM, which is a generalization of ordinary TCM, gives rise to the concept of space time codes (STC). With STC, coded signals are transmitted from multiple antennas at the same time over a Rayleigh fading channel. STC combines of transmit diversity, coding and M-ary modulation to mitigate problems imposed by the fading channel, Two types of STC, space time coded modulation (STCM) and block STC, are discussed in this thesis. Furthermore, a soft-output decoder for block STC is derived, and used to decode a serially concatenated code composed of an outer TCM code and an inner block STC.;In the final part of the thesis, we combine the concepts of STC and macrodiversity, which is the process of using multiple base stations to communicate with a single mobile station. Simulation results are shown for two types of macrodiversity systems, one using two base stations and another using three base stations. For the system that uses three base stations, we compare the performance of 120-degree sectorized antennas and 60-degree sectorized antennas, and show the tradeoff between these two types of sectoring.

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