OFDM用パンクチュアード符号の特性検討

抄録

A lot of works have been performed for the digital terrestrial television systems using orthogonal frequency division multiplexing (OFDM). One of important points to realize a robust system against noise and disturbance is an error-correcting code and its decoding technique. A punctured convolutional code with the constraint length of 7 is already decided as the inner error-correcting code of the European digital terrestrial TV system. This paper discusses basic characteristics of the code, combined with QAM or DAPSK systems, under the additive white Gaussian noise (AWGN) channels. The bit error rates (BERs) are compared between the hard and soft-decision methods for the QAM and DAPSK systems. Especially, a few different types of soft-decision techniques are numerically examined for the DAPSK systems. The results show that the punctured convolutional code attains the coding gains of 2〜5 [dB] for the QAM systems. However, in some cases, the code can only realize very small or even negative gains for the DAPSK systems.