On the Coded OTFS Systems with Partial Frequency Resources

This paper provides a pairwise error probability (PEP) performance analysis of coded orthogonal time frequency space (OTFS) systems utilizing frequency resources less than the FFT size. This is a potential scenario if OTFS is adopted on top of orthogonal frequency division multiplexing (OFDM) in future mobile communication systems such as 6G and beyond, where the allocable frequency resources may be less than the FFT size used for OFDM modulation due to the nature of its oversampled numerology. Additionally, OTFS and OFDM may be multiplexed within the same time-frequency resource grid. Our PEP performance analysis derives the necessary condition to achieve full diversity gain and confirms that the coding gain differs between the cases of allocating the partial and entire frequency resources.