# An In-Depth Review on Blockchain Simulators for IoT Environments
## 4 A Systematic Review of Blockchain Simulators in IoT
### Overview of Used Blockchain Simulators  
In Table 1, we provide the names of the simulator, the article from which the simulator was used, and the layer of the blockchain that it is capable of simulating. In Table 2, we provide further information about the simulators: the language that the simulator runs on, the last date of commit, and links to the source code. ### Overview of Used Blockchain Simulators  
In Table 1, we provide the names of the simulator, the article from which the simulator was used, and the layer of the blockchain that it is capable of simulating. In Table 2, we provide further information about the simulators: the language that the simulator runs on, the last date of commit, and links to the source code. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Simulator** & **Author and Sources** & **Title** & **Simulator Type** \\ \hline Blocksim & Alharby and Moorsel [24] & BlockSim: An Extensible Simulation Tool for Blockchain Systems & Network, Consensus, Incentives \\ \hline Simblock & [PERSON] [25] & Simulating a Blockchain Network with SimBlock & Consensus, network \\ \hline Omnet++ & [PERSON] et al. [26] & The Applicability of Blockchain in the Internet of Things & Network \\ \hline NS3 & [PERSON] et al. [27] & A Trust Architecture for Blockchain in IoT & Network, Consensus \\ \hline NS2 & [PERSON] et al. [28] & Decentralized Authentication of Distributed Patients in Hospital Networks using Blockchain & Network \\ \hline Matlab & [PERSON] et al. [29] & Home IoT device management blockchain platform using smart contracts and a countermeasure against 51\% attacks & Network \\ \hline Ethereum & [PERSON] et al. [30] & An Application of Ethereum smart contracts and IoT to logistics & All 5 layers \\ \hline iFogSim & [PERSON] et al. [31] & iFogSim: A Toolkit for Modeling and Simulation of Resource Management Techniques in Internet of Things, Edge and Fog Computing Environments & Network \\ \hline Hyperledger Sawtooth & [PERSON] et al. [32] & Smart Contract-Based Blockchain-Envisioned Authentication Scheme for Smart Farming & Consensus \\ \hline \hline \end{tabular}
\end{table} 
Table 1: A representation of simulator article and simulator type. Figure 4: Number of IoT papers used versus their publication dates. When it comes to simulator types, most simulators are capable of only simulating one layer with a mix of network and consensus. Exceptions to the one-layer simulators would be Simblock, NS3, and Blocksim. NS3 and BlockSim are both capable of simulating network and consensus while Blocksim has the extra incentives layer [24]. This might be relevant for those who are looking to incentivize their IoT devices, so more people are willing to use them. Figure 5 shows a bar graph of which layers are more likely to be simulated with respect to the fifteen simulators shown in Table 1. Most of the simulators are simulating the network layer, with the second most simulating the consensus layer. Only a few of the simulators are operating under the data, execution, and application layer. However, when comparing this data to the qualitative data found in Table 1, it is shown that the simulators simulating layers other than the network and consensus are not exclusively running these layers, but instead running all five layers. Since the network layer is the most popular layer