High Precision Timing with Parabolic Equation Fitting in Narrowband Systems.

Zou Zou,Xu Xu

doi:10.3390/s19194164

Abstract

Timing forms the basis of wireless communication systems. Orthogonal frequency division multiplexing (OFDM) technology has strict requirements for synchronization performance, and timing errors lead to interference between subcarriers and symbols. Although cyclic prefix (CP) can relax the timing requirement, high precision timing is still necessary and can release the pressure on CP. Due to the uncertainty of signal arrival, there is a sampling offset between the sampling sample’s timing and the real timing, which can be large in the narrowband system with a low sampling rate. In this paper, we propose a parabolic equation fitting method to improve the timing precision in narrowband systems that have two times the rate of the Nyquist sampling rate. The proposed timing method is easy to implement, with low additional complexity compared to traditional timing detection and is based on traditional direct correlator output.

Highlights

The Internet of Things (IoT), which aims to connect all the physical objects in the world, has gained a lot of attention in recent years [1]
The sampling offset was small in the wideband system due to the high sampling rate, but
The sampling offset was small in the wideband system due to the high sampling rate, but in in the the narrowband system it was a nonignorable factor, especially when the sampling rate was low

Summary

Introduction

The Internet of Things (IoT), which aims to connect all the physical objects in the world, has gained a lot of attention in recent years [1]. In mission-critical IoT, low latency and high transmission data rates are the most important requirements, while in massive IoT, the number of access devices can be very large so low cost is necessary. There are a lot of low power wide area network (LPWAN) technologies with narrowband transmission on unlicensed spectrums that have been proposed for massive IoT applications in recent years, such as LoRa and Sigfox [12]. In the work of Jun Zou and Hai Yu [16], a conjugated Zadoff–Chu (ZC) sequence based synchronization signal is fully studied in order to reduce timing drift caused by large frequency offset. In [17], an effective method is proposed to reduce the complexity of NB-IoT cell search by splitting narrowband secondary synchronization signal (NSSS) generation formulas.

System Model

Parabolic Equation Fitting Timing

In Figure the ZC sequence is used the parameters as Figure

Simulation Results

Timing detection of parabolic equation fitting with times of the

Conclusions