A New Class of Convolutional Codes for Coded TPSK Schemes

Convolutional codes have been widely used in several kinds of communication systems because of its excellent coding gain. Recently, the coded TPSK (Ternary phase shift keying) scheme has been proposed and it was shown that the scheme has attractive features for mobile communication systems; excellent bit error characteristics and small amount of amplitude fluctuation. The latter feature is very appealing for usage in mobile terminals in which non-linear amplifiers have to be used. One example of the new convolutional codes was shown in the previous work. However the general properties and the generator polynomials for best codes have not been clarified. In this paper, the general definition of the new convolutional codes is given. Some generator polynomials are obtained by computer simulation. The minimum distances of these codes are clarified. It is also shown that the error performance of the coded TPSK scheme using the new convolutional codes is excellent. Key-Words: Error correcting code, Convolutional code, Minimum free distance, Coded modulation, Ternary phase shift keying, Mobile communication