## 5 A User-Centric Perspective for the Internet of Medical Things
It is composed of five entities: the IoMT Devices; the User Nodes, able to manage one or more IoT devices aggregating, encrypting, and sending data to the storage node; the Doctor Nodes that are doctors or companies providing healthcare services; the Accounting Node: a particular node maintained by the consortium to verify whether the transactions from doctor nodes are correct and valid; Storage Nodes, IPFS-based systems maintained by the consortium that collaboratively store complete encrypted users'IoMT data and encrypted doctors' diagnoses in a distributed manner. IoMT devices send health data to the User Nodes that encrypt the data forwarding them to an IPFS storage that takes care of \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Authors** & **Consensus** & **Mention Centricity** & **User-Centric** \\ \hline [PERSON] et al. [38] & Restricted & No & No \\ \hline [PERSON] et al. [39] & Decentralized & Yes & Yes \\ \hline [PERSON] et al. [40] & No Consensus & No & No \\ \hline [PERSON] et al. [41] & Restricted & No & No \\ \hline [PERSON] et al. [42] & Restricted & No & No \\ \hline [PERSON] et al. [43] & Decentralized & No & No \\ \hline [PERSON] et al. [44] & Decentralized & Yes & Yes \\ \hline [PERSON] et al. [47] & Decentralized & No & Yes \\ \hline [PERSON] et al. [49] & Decentralized & No & Yes \\ \hline [PERSON] et al. [50] & Decentralized & Yes & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Evaluation of user-centricity in research papers labeled as Applicative. User-centricity is the ability of the user to own its data without the risk of tampering or loose power by consortiums decisions. the transaction to the Userchain. The Doctor Node is then able to give real-time online diagnoses readable by the patients reading the Docchain. The ability to have control over data by the user is significant and goes towards a user-centric solution. [PERSON] et al. [40] proposes a Blockchain-based eHealthcare system using Hyperledger Fabric interoperating with wireless body area networks (WBAN) which use the WBAN to network the devices of the patients and the Blockchain technology. Hyperledger Fabric provides a private, permissioned network where participants trust each other. The actors of such a system are: patients, doctors, healthcare institutions, and suppliers. The workflow of the proposal is the following: the patients transmit the data collected through the WBAN from the sensors to the centralized devices. The devices wait for the instructions by the centralized device that later generates the final record of information to submit to the Blockchain, in order to update the physical data of the patients. In this kind of architecture, the data are effectively kept safe: healthcare professionals get access only to the records of their patients. Anyway, in this implementation, Hyperledger Fabric does not require any consensus mechanism at all making it challenging to know if the ledger has been tampered with, leading to a less secure system. In this solution, the data management layer does not seem to allow secure control over data, and so we cannot say it is user-centric. [PERSON] et al. [41] propose a Blockchain-based system named Healthsense where a sensor collects real-time data of a patient's medical condition and stores it in the Blockchain for later use with smart contracts. The solution makes use of IPFS for off-chain storage, and, through a smart contract, the sensor is put in communication with the Blockchain. In some way, this allows IoMT devices to find each other and begin trading data off-chain autonomously or with the platform. Anyway, researchers' architecture does not specify any consensus model, and, eventually, it will be restricted since it is thought to work specifically for hospitals. [PERSON] et al. [42] proposes a platform architecture based on a Permissioned Blockchain for diabetes self-management. The researchers said that integrating Blockchain with low power devices, such as the ones used for diabetes monitoring is a difficult task.