s [215]: 1. Link-level simulator (LLS): It analyzes the performance of PHY layer for UL and DL point-to-point wireless link between a BS and UE. It involves the channel coding, waveform, and modulation. 2. System-level simulator (SLS): It evaluates the performance of MAC layer such as scheduling and radio resource management. 3. Network simulator (NS): It analyzes the performance of high layers with the core network. Table 1.10 compares LTE and 5G simulators including MATLAB, NS-3, Vienna simulator, OpenAirInterface (OAI), and 5G K-simulator. MATLAB provides LLS solutions including 5G NR DL waveforms, beam sweeping, and SO on [210]. On the other hand, NS-3 LTE EPC network simulator (LENA) module provides a NS with an abstraction of the physical layer [211]. Meanwhile, Vienna simulator offers a multi-use MIMO, beamforming, and mm-Wave solutions for the 5G technology [212]. Moreover, OAI simulator provides solutions for all layers of E-UTRAN stack protocol as well as the core functionalities [213]. Similar to OAI, the 5G K-simulator develops LLS, SLS, and NS based on the 3GPP Release 15 [214]. Among the compared simulators in Table 1.10, NS-3, MATLAB, and OAI gain high credibility in the R&D community. The credibility of these simulators can be measured by the number of published articles each year by using these simulators. For this reason of high credibility, in this section, the solutions provided by OAI, NS-3, and MATLAB are investigated and compared. Table 1.10 Comparison between 5G simulators Simulator NR (5G) Credi-bility Open source Lang-uage Compl-exity User manual Fortran MATLAB Simple [210] Abstr-action NS3 [211] Vienna [212] Acad-emia Fortran OAI [213] 5G K-Sim [214] M. Alfaqawi et al. 1.5.1.1 OpenAirInterface (OAI) It is an open-source software developed by EURECOM and OAI alliance, involving Orange, Nokia Bell Labs, Qualcomm, TCL, and others. It provides RAN and core functionalities for LTE and 5G systems including IoT technologies such as NB-IoT. It supports the features of LTE, LTE-Advanced, and LTE