Research Article Channel Estimation and Peak-to-Average Power Ratio Analysis of Narrowband Internet of Things Uplink Systems Md Sadek Ali , Yu Li, Md Khalid Hossain Jewel, Oluwole John Famoriji , and Fujiang Lin Micro-/Nano-Electronic System Integration R&D Center (MESIC), Department of Electronic Science and Technology, University of Science and Technology of China (USTC), Hefei, Anhui, 230026, China Correspondence should be addressed to Md Sadek Ali; sadek@mail.ustc.edu.cn Received 27 November 2017; Accepted 21 May 2018; Published 5 July 2018 Academic Editor: Pavlos I. Lazaridis Copyright © 2018 Md Sadek Ali et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Narrowband Internet of Tings (NB-IoT) is a cellular based promising low-power wide-area network (LPWN) technology standardized by the 3rd Generation Partnership Project (3GPP) in release-13 as a part of the future 5th Generation (5G) wireless communication systems. Te main design target of NB-IoT was to enhance radio coverage by repeating signal over an additional period of time for the ultralow-end IoT devices that would be operated in extreme coverage environments. But the power efciency of the low-cost NB-IoT user equipment (NB-IoT UE) in the uplink is the major concern. Coverage improvement from signal repetitions depends on the channel estimation quality at extremely bad radio conditions. Te typical operating signal-to-noise ratio (SNR) for NB-IoT is expected to be much lower than the zero. In this paper, we have proposed two efcient narrowband demodulation reference signal (NDMRS)-assisted channel estimation algorithms based on the conventional least squares (LS) and minimum mean square error (MMSE) estimation methods. Te theoretical analysis and the link-level performance of our proposed estimation methods are presented. Simulation results exhibit that the proposed methods provide better estimation precision compared to the traditional LS and MMSE methods at the low SNR situations. Furthermore, we have analyzed the raised- cosine (RC) and square-root-raised cosine (RRC) pulse shaping to reduce peak-to-average power ratio (PAPR) as an uplink transmit flter. Te PAPR values are evaluated through extensive computer simulations for both single-tone and multi-tone transmissions. Our evaluation results vindicate that the RRC pulse shaping with lower PAPR values is feasible to design of practical NB-IoT uplink transmitter and increases power efciency. 1. Introduction Te Internet of Tings (IoT) is a novel prototype which ofers massive connectivity to physical objects, radio-frequency identifcation (RFID) tags, vehicles, sensors, actuators, and other things embedded with electronics to the Internet. IoT allows things to be connected across existing network infrastructure, interacting with each other through unique addressing schemes, thus reducing extra deployment cost and improving accuracy and efciency. According to [1], there will be more than 30 billion devices connected wirelessly to the IoT by 2020. Nokia [2], based on Machina research 2015, predicted that about 30 billion connected IoT devices will be deployed by 2025, of which cellular IoT (CIoT) and low-power wide-area (LPWA) modules are about 23 percent. Traditionally, mobile broadband networks need high throughput and low latency, whereas LPWA applications require low-throughput, extended coverage, low-cost, low complexity, scalability, low delay sensitivity, and high power efciency [3–6]. Tere are many short-range wireless communication technologies [7, 8] like Bluetooth low energy (BLE), Wi-Fi, Li-Fi, ZigBee, and Z-wave, to enable the IoT. Some of the IoT enabling technologies [9, 10] such as SigFox and LoRa that are operating in license-exempted band (i.e., industrial, scientifc, and medical (ISM) band). On the other hand, Global System for Mobile Communications (GSM) and the 3rd Generation Partnership Project (3GPP) standard Long- Term Evolution (LTE) are operating in licensed spectrum to enable the IoT. A new cellular based IoT enabling technology Hindawi Wireless Communications and Mobile Computing Volume 2018, Article ID 2570165, 15 pages https://doi.org/10.1155/2018/2570165