## 3 Materials and Methods in Designing Open-Source On-Premises Experimental Communication Platforms  
After thoroughly studying the above tools and platforms, we focused on the development of a private mobile base station for the needs of the experimental platform. Until now, all the efforts to implement such an endeavor underscore the strategic adoption of modern technologies such as VoIP, SD-WAN, LTE, and Wi-Fi to improve communication efficiency and fidelity. Each study directs its attention to different applications, covering a wide range from disaster communication to corporate VoIP and community networking. Additionally, differences are observed in the specific technological methods employed and the thematic focuses of the research, with some prioritizing performance analysis and optimization while others focus on practical application and demonstration of solutions. Despite these nuanced distinctions, the collective body of research fosters perceptible progress in communication technologies, consistently addressing multifaceted challenges across various frameworks.  
The solution presented below is based on the integration of open-source technologies within private communication infrastructures, focused on ECSs. It proposes a low-cost, open-source experimental communication platform designed for emergency scenarios where traditional channels may provide no services or functionality. This platform uses SDR devices to enable seamless voice communication over a private LTE network. The integration of OAI software and an Asterisk server facilitates the establishment of a portable mobile base station. It allows for sensor data transmission, image and video dissemination, and real-time video conferencing while adhering to stringent mobile network security protocols.  
Given that we need to build a low-cost, open-source experimental platform, we have chosen to use the OAI Public License V1.1 software for the Evolved Node B (eNB) and EPC implementation. Thus, in our experiment, we used two laptops, 1 for the eNB and 1 for the EPC components, with the minimum system requirements of an Intel i5 6600 and 5600, respectively, with 16 GB memory and 256 GB SSD in each laptop. Table 2 depicts the acceptable experimental platform SDR device characteristics. We have selected the B210 SDR device, as a low-cost option that enables us to experiment in a large scale of frequencies including some unlicensed bands, depending on the deployment area regulations. USRPs B210 operation is based on software control and programming, giving users the ability to define and control the behavior of the radio spectrum [13].  
Figure 1 shows the available implementation options for such a base station.  
The dotted lines show the variety of available open-source available implementation options according to each implemented technology, according to the desired outcome, that were derived from the researched literature. The first column refers to the SIM card options, the second to the supported UE devices, the third to the eNB type, and the fourth to the EPC. For real-time voice and data transmission, the OAI LTE implementation was preferred instead of the OAI NB-IoT, which does not support voice transmission. \"Open Cells\" SIM cards and open-source UICC Programmer V3.2 with the necessary card reader have been used. These SIM cards are suitable for Android and iOS phones and even for SIM7000 modules for sensor data transmission.