Random Access Preamble Generation with Low Storage for LTE Networks

Abstract

Long Term Evolution (LTE) random access preambles are generated from cyclically shifted Zadoff-Chu(ZC) sequences of prime length by using so-called Discrete Fourier Transformation-Spread-Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) modulation. In this paper we propose a novel preamble generation to reduce the storage and complexity of cyclically shifted ZC sequences’ Discrete Fourier Transformation (DFT). The proposed preamble generation allows the DFT of cyclically shifted ZC sequences to rely only on several constant factors and the elements of non-cyclically shifted ZC sequences which have already been generated. This preamble generation merely requires the storage of several constant factors, while avoids large storage and complex computation of complex exponential function.