Emulation Techniques for High Speed Train Measurements in 6G Mobile Communications

High-speed train (HST) scenarios are expected to be typical scenarios for sixth-generation (6G) wireless communication systems. Due to the high cost, complexity, and time consumption of high-speed measurement campaigns, this particular environment poses challenges for performance measurements. Furthermore, it is not possible to perform repeatable measurements in a controlled high-speed environment in most cases. Using proposed methods of time-stretching the transmit signals, fortunately, such experiments can be emulated at lower velocities by inducing effects caused by highly time-varying channels. Therefore, the cost and complexity of high-speed measurement campaigns are considerably decreased. Foremost, this thesis considers the problem of unequal channel estimation quality between proposed time-stretching methods. This is an auxiliary unwanted side effect of proposed time-stretching methods. To ensure a fair comparison between resamplingand insertion-based time-stretching methods, I adapt the pilot-based channel estimation scheme within the time-stretching method. Besides the unequal channel estimation quality, I consider the problem of significantly increased Peak-to-Average Power Ratio (PAPR) in time-stretching methods. To solve this problem, I apply strategies to reduce the PAPR. Thereby, time-stretching methods can be used more efficiently in practical communication systems. In addition, this thesis investigates the applicability of the proposed time-stretching methods for 6G candidate waveforms. Evaluation is performed by simulations in high-speed environment scenarios. More specifically, I compare the performance of proposed methods by employing waveform candidates proposed for 6G wireless communication systems, such as Orthogonal Frequency Division Multiplexing (OFDM), Filter Bank Multi-carrier (FBMC), and Universal Filtered Multi-carrier (UFMC).