# Analysis and Experimental Validation of Efficient Coded OFDM for an Impulsive Noise Environment
## 1 Introduction
To validate the proposed physical layer, it is essential to compare the theoretical results to the experimental ones. Indeed, in recent years, Software-Defined Radios (SDRs) have drastically changed the way that research and experimental works are done in the wireless arena. Their advantages over traditional hardware-based radios are that significant aspects of the communication stack are implemented in software programs [14], while in hardware radios, the lower layers are realized in hardware, making their use extremely constrained when modifications on physical or medium access layers are required. Thus, with SDRs, most of the radio functionality and signal processing are implemented in software that runs on a computer, and the only task of the hardware is taking care of functions, such as transmissions and reception of the signal [15]. We now propose a combined analysis and experimental validation of the best coding schemes with an appropriate OFDM signal. The objective is to come up with an optimized overall physical layer to ensure better communication in substations. For this purpose, we use the GNU's Not Unix Radio (GNU Radio) platform, which is presently the open-source reference apparatus for academic work and wireless research [15; 16; 17; 18; 19] allowing the researcher to implement signal processing blocks with no additional hardware requirements. We implement a new block namely \"RC Encoder + WiFi Mapper\" to perform error correction. It is based on the implementation of _gr-ieee_ 802.11 proposed by [PERSON] et al. [20; 21]. The main contributions of this paper are summarized as follows:  
* Implementation of a new block performing forward error correction code based on the RC code and convolutional encoding in GNU Radio. * Setup design and impulsive noise measurements in a controlled laboratory condition: this is a new method using the GNU Radio instead of an oscilloscope as proposed in other laboratory tests. * Over the air experiments in an impulsive noise environment in a laboratory: several scenarios are made up including Line-Of-Sight (LOS) and Non-Line-Of-Sight (NLOS) situations by also considering the impulsive noise level, the distance between the emitter, the receiver and the source. The rest of this paper is organized as follows. Section 2 presents an overview of the system. It first shows the simulation chain before describing the transmitter and the receiver designed in GNU Radio. The setup for impulsive noise measurements in a controlled laboratory is detailed and some results are also presented in Section 3. The obtained results with this specimen demonstrate that this new method can reproduce the impulsive noise accurately. Section 4 provides the specifications and the measurement scenarios. In Section 5, we present the performance analysis of the obtained results. It first details the network performance by examining the overall rate of traffic and the average delay, which shows that the LOS situation presents better performance than the NLOS configuration. After that, the Bit Error Rate (BER) performance in the presence of impulsive noise obtained by experiments is presented. The performances obtained in this section are globally satisfactory even if we can notice a little degradation in some cases. A comparison between the simulation results shown in [13] and the experimental results is also overviewed in this section, which confirms that the same performances are maintained with several impulsive noise level voltages. Finally, the conclusion and perspectives are given in the last section.