Random Access Preamble Detection for Aeronautical Communication Systems

Aeronautical communication (AC) is considered as one of the core technologies for future wireless networks. In practical AC scenarios, the communication links suffer from severe Doppler effect caused by the high mobility of the aerial user equipment (AUE) on the aircraft, resulting in a rapidly time-varying propagation channel. In addition, compared with conventional terrestrial communication systems, an AC system is usually expected to support a much wider cell coverage. In this case, the round trip delay (RTD) of signal transmissions becomes larger and more difficult to be estimated, thus making it challenging to design a reliable random access scheme for AC scenarios. To address the above-mentioned issues, in this article, we propose a new random access preamble detection algorithm for AC systems. The proposed scheme employs short preamble formats and detects the preamble by exploiting a shifted partial combination mechanism. Thus, it is capable of offering a better detection performance and improved spectral efficiency (SE), while still maintaining a large coverage under high Doppler shifts. Furthermore, we design an RTD estimation approach based on the so-called dual-end correlation operation, which can help to achieve more robust RTD estimates. The superior performance of the proposed technique is verified through both simulations and lab experiments in an emulated challenging scenario, where as many as 30 AUEs traveling at a velocity of 1260 km/h within a cell radius of 200 km can be supported.