# Using Blockchain for Data Collection in the Automotive Industry Sector: A Literature Review
## 3 Results
### Connectivity  
Despite the benefits of blockchain, this technology suffers from significant drawbacks, such as transaction latency, minimal throughput, and difficult commit processes [9]. In addition, the time it takes to update a transaction onto a blockchain is the major source of worry [10]. This is due to the significant amount of processing required to commit \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Aspects** & **Challenges** & **Description** & **Authors** \\ \hline \multirow{8}{*}{Technological} & \multirow{4}{*}{Privacy} & Protection of personal data and information collected from vehicle systems, such as location data and financial information. & [4, 10, 11, 12, 18] \\  & & Security attacks & Security vulnerabilities in the vehicle’s systems (hardware or software components) or any flaws in the connection. & [4, 5, 9, 11, 18, 19] \\ \cline{2-4}  & \multirow{4}{*}{Scalability} & The impact of blockchain use on data collection in the automotive industry from a scalability angle. & [4, 9, 10, 16, 18] \\ \cline{2-4}  & \multirow{4}{*}{Performance} & The efficiency of the proposed solutions for data gathering. & [4, 9, 10, 16, 18, 19, 20] \\ \cline{2-4}  & & Cost & The transaction, services, and data-gathering costs. & [4, 9, 10, 11, 13, 16, 19] \\ \hline \multirow{8}{*}{Environmental} & \multirow{4}{*}{Connectivity} & How a vehicle can be connected to its surroundings and communicate with them. & [9, 10, 11] \\ \cline{2-4}  & & The different alternatives to monetize data collection & \\ \cline{1-1} \cline{2-4}  & \multirow{2}{*}{Monetizing} & In the automotive industry thanks to blockchain technology. & [4, 9, 10, 11, 13, 15, 16, 19] \\ \cline{1-1} \cline{2-4}  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Categories of reviewed articles. a transaction to the ledger for all agents [9]. To solve this issue, some of the solutions considered bulk report commits. That is, when a predetermined number of reports have been gathered, then a transaction is issued that causes numerous reports to be stored in the blockchain at the same time for the cost of a single commit [9]. Another approach is, instead of having a single blockchain layer in charge of communication over a broader territory, distinct blockchain levels inside smaller regions would make it easier for a limited number of cars by focusing on minimizing message size to increase transaction speed [10]. In Reference [10], receiving data from a blockchain once or hundreds of times had no significant impact on the execution time. However, storing data takes a long time, since the message must be mined before it can be added to the smart contract. In Reference [18], a large number of devices could connect simultaneously to the same base station to upload data when cluster heads uploaded messages to their nearest base stations. Most of the proposed solutions have been tested and have shown significant improvement in blockchain technology, particularly with respect to the processing time. In Reference [4], the processing time associated with validating blocks decreased when using the Lightweight Scalable Blockchain (LSB) instead of the Bitcoin blockchain. In Reference [15], using a blockchain consensus algorithm instead of the PBFT (Practical Byzantine Fault Tolerance) algorithm reduced the time of uploading and downloading from 46 to 17 ms.  
Another challenge to consider is that, as vehicles are fast-moving objects, there is not always a good connection with the receiver. In Reference [11], The researchers focused on the calculation of the 4G network in Italy. Even if the best case cannot be reached most of the time, we can certainly assume a bandwidth of 5.5 MB per second, which is sufficient for their solution, where the average message size is less than 5.5 MB [11]. In Reference [10], a hybrid system was proposed, either via Wi-Fi or via mobile Internet (3G/3G+/4G). Before transferring data to the server, the system in Reference [10] captured data locally.