Symbol FFT RACH processing methods and devices

Abstract

Methods and devices for extracting a RACH preamble using as input a number of Fast Fourier Transformed symbols, in order to extract a random access channel (RACH) preamble from a signal received in a base station from a user device, in a radio communication system, are provided. An initial cyclic prefix (symbol CP) is removed prior to performing FFT on symbols. After (1) selecting from the FFT of a symbol frequencies corresponding to the RACH band all other non-RACH frequency bins having been set to zero, (2) shifting the signal to baseband and (3) performing a FFT on the baseband signal, a phase adjustment is performed to compensate for group delays due to symbol CP gaps occurring when generating the baseband signal, the phase adjustment being determined individually for each symbol.

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