Pilot waveform for satellite IoT transmission with timing and Doppler uncertainty

Uplink transmissions in low duty cycle satellite IoT systems are often received with large timing and Doppler uncertainty. The utilised pilot waveform must thereby support the estimation of these parameters. We present a flexible design based on the concatenation of multiple Zadoff-Chu (ZC) sequences with different roots, which can be parametrised to operate at very low signal-to-noise ratios. The Doppler and timing resolution of the design scales with the sequence length. We present the design and the corresponding frequency domain detector/estimator, and illustrate its behavior through examples. We present a feasibility analysis for an FPGA based implementation.