LTE and LTE Advanced

In this paper, we address the problem of primary synchronization in Long Term Evolution (LTE) systems, and we assess the Frequency Offset (FO)–combating capabilities of the two studied reduced‐complexity approaches. We also provide a comparative study that covers computational complexity, time synchronization, and sector search performance considering multiple antenna configuration and under standardized channel models. The studied approaches, referred to as Simply Differential (SD) and Doubly Differential (DD) exploit Zadoff‐Chu (ZC) sequences to which differential correlation–based metrics are tailored. The SD approach computes differential correlation between the received samples and compensates the output with an adjustment frequency that depends on the training ZC sequence. This allows coarse time synchronization and sector search in a sole stage, which is a particular feature compared to most of the existing methods. The DD approach performs DD correlation of consecutive samples to detect a ZC sequence pattern within the received signal. To accomplish primary synchronization, it requires a second stage in which cross‐correlation is performed between the received signal and the local known ZC sequence candidates. This allows to identify the sector and helps to fine‐tune time synchronization. To assess their FO‐combatting capabilities, we examine the impact of an FO on the SD and DD metrics through theoretical analysis and simulation. The study shows the sensitivity of the SD approach to the FO and the immunity of the DD one. Simulation and numerical results prove the efficiency of the presented approaches under LTE standardized channel models and validate the analysis of the FO effect on time synchronization performance.

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“…In LTE systems, a total of 504 physical layer cell‐ID are defined as