Coded orthogonal signaling.
Ha, Tri T.
Robertson, R. Clark
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In this thesis, a new scheme of encoding orthogonal MFSK signals with convolutional codes is proposed. Instead of separating the code and the signals as is done conventionally, here the m outputs of the convolutional encoder of rate k/m are used to select the M = 2m orthogonal FSK signals. This combined coded system is called trellis-coded modulation MFSK (TCM/MFSK). The free distance of TCM/MFSK codes is found computationally. Asymptotic coding gains (ACG) of several TCM/MFSK systems relative to uncoded MFSK systems having the same bandwidth efficiency (bits/s/Hz) are calculated. Both analytic descriptions and natural mapping implementations of TCM/4-FSK with rate 1/2 and TCM/8-FSK with rate 2/3 for several constraint lengths of the convolutional codes are given. The analytic description of TCM/MFSK is also obtained computationally.
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