Effective ranging techniques in LTE

Abstract

Effective uplink ranging using Physical Random Access Channel (PRACH) enables LTE users to work with a small cyclic prefix overhead even over 3 km to 5 km links. Ranging includes the detection of the preamble index and estimating the timing advancement value. Our works compares two different algorithms for estimating the timing advancement, namely (i) the conventional strongest path approach (SPA) and (ii) the proposed weighted mean approach (WMA). Both approaches use the Neymann Pearson (NP) criteria for the preamble index detection [1]. Simulation results indicate that the proposed WMA is significantly superior to the SPA, especially in large spread channels. The impact of the PRACH transmitter and receive filter order on these two approaches, as well as the adjacent channel interference (ACI) behaviour of these PRACH signals is also discussed in this paper.