###### Abstract
The network comprised many connected electrical devices functioning as impulse noise generators for real-time data transmission and error sequence measurements for different M-QAM schemes. The impulse noise error was measured experimentally in this study using two distinct measurement scenarios. These were scenarios with weakly interrupted and strongly interrupted noise. A single device was connected to the channel in the weakly interrupted case, whereas, in the strongly interrupted case, two indoor electrical devices were used as noise generators for the channel. We previously presented some preliminary results from this work [30], which focused on the experimental evaluation of the effects of impulsive noise on transmitted data while using a single device as an error generator. Data sent over an indoor SD-PLC were tested under a weakly interrupted scenario in which a compact fluorescent lamp (CFL) bulb and a hairdryer were turned on and off repeatedly. This investigation built upon earlier studies by considering weakly and strongly interrupted noise conditions. Several tests were performed to investigate how the use of electrical devices in the home affects data transmission over power line channels. In the weakly interrupted scenario, only one device was considered: a laptop charger and a computer monitor. In the strongly interrupted scenario, two household devices were combined: a CFL bulb, a hairdryer, a laptop charger, and a computer monitor. A comprehensive investigation was conducted to determine how the uncoordinated turning on and off of different appliances in the home could affect the quality of the digital data sent over an indoor SD-PLC system. For more information on the detailed experiments, the SD-PLC system design approach, and the modeling technique used in this study, the reader is referred to [31]. This study makes three primary contributions in the areas that follow. First, an experimental test bed was set up with a software-defined M-QAM-based NB-PLC transmitter and receiver system for the measurement and modeling of impulsive noise errors in a functional in-house NB-PLC environment operating in the CENELEC C frequency band. This transmitter and receiver system used M-QAM modulation techniques (4-QAM, 8-QAM, and 16-QAM), MATLAB/Simulink software, and USRP hardware for real-time data transmission and reception. Second, we used the SD-PLC experimental test bed to transmit real-time data for various M-QAM schemes. This test bed consisted of networked indoor electrical equipment that acted as impulse noise generators on the network and collected experimental data (error sequences). Lastly, we examined the effectiveness of the Fritchman-Markov model (FMM) and the Baum-Welch algorithm (BWA) for modeling impulsive noise error patterns in an in-house NB-PLC environment. The rest of this work is presented in the following order. Section 2 describes the M-QAM SD-PLC transceiver system model, Section 3 discusses the Fritchman-Markov model used in this study for discrete channel modeling, and Section 4 describes the experimental setup and measurement procedure. Section 5 presents the measurements, modeling, and model analytical validation results. Finally, Section 6 contains the concluding remarks.