Coded Nonuniform Phase/Frequency Modulation

Aminuddin CHALID  Iwao SASASE  Hiroyuki YASHIMA  Shinsaku MORI  

IEICE TRANSACTIONS (1976-1990)   Vol.E72   No.8   pp.903-911
Publication Date: 1989/08/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Communication Theory

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The nonuniformity of signal constellation on coded phase/frequency modulation is investigated to obtain further improvement on the error performance over conventional uniformly spaced coded phase/frequency modulation. The analytical method for evaluating the Euclidean distance of nonuniform FSK/PSK signal is presented. In particular, the joint design of m/(m1) systematic convolutional encoders and nonuniform 2FSK/2mPSK are considered, and especially for 2FSK/4PSK and 2FSK/8PSK the behavior of the free Euclidean distance is evaluated by varying the modulation index, the rotation angles which determine the nonuniform signal constellation, and the mapping rule by set partitioning. The results show that by designing compared with the conventional coded uniform phase/frequency modulation may be obtained without increasing average or peak power or changing the bandwidth of the transmitted signals. The maximum value of the free Euclidean distance of codes can be obtained when the PSK signal constellation of one carrier frequency is the same as those of the other carrier frequency, and the mapping rule used in coded uniform FSK/PSK system is not always good enough when the nonuniformity in the signal constellation is introduced.