6G and Beyond: Hardware-in-the-Loop Experiments with OTFS Modulation Using SDR

High mobility systems call for efficient techniques to provide reliable communication. Orthogonal Time Frequency Space (OTFS) has been seen as a promising candidate to mitigate high Doppler and multipath challenges. This paper reports our current progress in implementing an OTFS system on a Software Defined Radio (SDR) platform. Firstly, hardware impairments are studied via trials on SDR, and the solutions are applied afterward. OTFS utilizes full Time-Frequency diversity, which incurs additional challenges such as high initial latency and required sharp filtering in hardware. The initial latency challenge is inherent in OTFS. The challenge of sharp filtering can be alleviated with multirate processing. Similarly, synchronization is one of the most critical tasks, as the resulting constellation completely fills up with noise if an incorrect start of frame is chosen. We tested our OTFS system with different processing rates in a real wireless environment at 2.4 GHz carrier frequency.