Root Pair Selection for Two-root Random Access Preamble

摘要

In some scenarios such as satellite communication, the initialization of wireless access based on traditional Zadoff-Chu random access preamble may fail due to the large Doppler frequency shift. The two-root preamble, which consists of two Zadoff-Chu sequences with different roots, has been considered as one promising solution for large Doppler. However, in the receiver side the frequency and time offset estimation errors of two-root preamble are always relatively large. In this paper, the underlying reason of the large errors is theoretically analyzed, based on which a novel root pair selection method is proposed. Simulation shows that the resulting root pairs lead to much lower errors in frequency/time offset estimation.