BER Performance of OTFS With MRC-Based Detection Over the DVB-TU6 Channel

Abstract

Orthogonal time frequency space (OTFS) modulation has emerged as a promising waveform for high-mobility wireless communications owing to its inherent robustness against Doppler spread. This paper investigates the bit error rate (BER) performance of OTFS over the DVB-TU6 vehicular channel using a low-complexity maximum ratio combining (MRC)-based detector. The DVB-TU6 channel features a non-monotonic powerdelay profile representative of urban broadcasting environments, where reflections from buildings and large structures produce delayed paths that can exceed the power of the first-arriving tap - yielding a delay-Doppler channel structure fundamentally different from conventional models. The results reveal a characteristic flat-transition-flat BER behavior with increasing vehicle speed, where the onset and extent of the transition region are governed by the Doppler-domain resolution of the OTFS frame rather than the operating SNR. Increasing the Doppler-domain size shifts this transition toward lower speeds and narrows the BER gap between low- and high-mobility regimes by more accurately resolving the delay-Doppler channel structure, at the cost of increased frame duration and latency. In contrast, increasing the delay-domain size yields only marginal BER improvement despite the associated bandwidth increase, as the channel delay spread is already sufficiently resolved. These findings highlight the importance of channel-specific delay-Doppler structure in OTFS parameter selection and offer practical design insights for high-mobility urban vehicular scenarios.