## 1 Introduction  
Internet of things (IoT) represents the concept of the communication between plenteeous limited-power devices from various environments over a large-scale interconnected network without human involvement [1]. Over the last few years, the IoT has been successfully deployed in diverse fields, such as intelligent environment, medical care, and transportation logistics [1, 2]. With the anticipated evolution of the IoT market, the number of IoT devices has remarkably increased worldwide from 15.41 billion in 2015 to 23.14 billion in 2018, and it is expected to extend to 75.44 billion in 2025 [3]. Thus, many communication protocols and standards have been recently developed to support a wide range of IoT applications. These protocols and standards, such as near-field communication (NFC), ZigBee, low-energy Bluetooth (BLE), and wireless-fidelity (Wi-Fi), are mostly dedicated to short-range applications [4]. On the other hand, new low-power wide-area (LPWA) technologies have been developed to achieve wide-range communications, such as long-range wide area network (LoRaWAN), Sigfox, and weightless special interest group (SIG), that all operate in the unlicensed spectrum and have massive connectivity but require building new infrastructures [4; 5]. Moreover, the cellular systems have been considered potential solutions to provide massive connectivity for machine-type communication (MTC) devices. Therefore, the 3 rd Generation Partnership Project (3 GPP) has introduced a new cellular technology standard known as narrowband internet of things (NB-IoT) to support the IoT applications [6; 7]. The NB-IoT operates in a licensed spectrum, as it is based on the 3 GPP long-term evolution (LTE), and contrary to other unlicensed LPWA technologies, the same infrastructure of LTE is utilized in NB-IoT [8]. Furthermore, most features of LTE are inherited in NB-IoT, minimizing the complexity of LTE channels and signals to meet the constraints of low power and low cost in NB-IoT. Additionally, the number of these channels is decreased to fit the new frame structure of NB-IoT. The LTE protocol stacks in the evolved node B (eNB) and the user equipment (UE) are deployed in NB-IoT with a significant reduction in each layer's functionalities [5; 6]. The NB-IoT system is designed to occupy a bandwidth of 180 kHz, corresponding to one LTE physical resource block (PRB), which is deployed in three possible operation modes defined by 3 GPP to ensure the coexistence with LTE carriers without decaying the LTE performance. These operation modes are in-band mode, guard-band mode, and standalone mode (in the liberated GSM channels) [9]. Furthermore, the number of repetitions reaches up to 128 and 2048 repetitions in uplink and downlink, respectively, and that indeed improves the coverage [7]. A detailed description of the main building blocks of the narrowband physical uplink shared channel (NPUSCH) transmitter and narrowband physical downlink shared channel (NPDSCH) receiver as specified by 3 GPP standard is provided in this work. In addition, experimental results, including area utilization, power consumption, and clock latency of an FPGA hardware implementation of both NPUSCH and NPDSCH channels, are presented. The narrowband physical shared channels are responsible for the delivery of both user plane data as well as control information. However, only user plane data processing is discussed in this work. The main contributions of this work can be listed as follows:  
* Chain integration is performed between the uplink transmitter and downlink receiver, including the base station model between them. * A whole chain results for bit error rate (BER) versus signal-to-noise ratio (SNR), and it is compared with the ideal case. * The whole chain is synthesized and implemented on the FPGA, which acts as a UE model. * Mimic the reality by building a prototype using two FPGAs connected to USRPs to serve as the UEs. * Several hardware techniques are adopted to reduce power consumption while meeting all of the 3 GPP standard requirements.