## 2 Literature Review
### Classification of WBAN Routing Protocol
#### 2.1.7 WBAN-Enabled Blockchain Approaches  
[PERSON] et al. [53] presented an ethereum based protocol where a smart contract is used to establish communication between sensors and intelligent devices and store data in the blockchain. The real-time monitoring support provided by the smart contract enables medical personnel to get up to date medical records of the patient. [PERSON] et al. [54] describe the approach to integrate the blockchain with WBAN using multiple IoT devices. The blockchain provides trust and reliability between the parties while transforming data. Furthermore, the presented system also discussed several challenges that can be solved by concatenating both technologies like blockchain and WBAN. [PERSON] et al. [55] introduced a technique to incorporate WBAN with blockchain for securing electronic health records. The sharing of medical data between the parties is made secure and reliable using blockchain. Moreover, the blockchain provides authentication and authorization rules to validate each transaction within the network. The data is gathered using ECG and movement sensor plants on the human body. The QoS support is also enabled for remote monitoring, interoperability, and correspondence. [PERSON] et al. [56] presented an approach for securing the blockchain and WBAN integration. The proposed certificates authenticated key agreement (CLAKA) approach not only used to overcome the problem of a single node of failure in the network but also to prove authentication and authorization with common sharing of key between blockchain nodes and WBAN user. Similarly, [PERSON] et al. [57] presented an e-healthcare system based on blockchain integrated with WBAN, which provides security for patient data. The proposed system consumes fewer hardware resources while maximizing the data protection level. The remote monitoring based on the blockchain offers the data interoperability, where data are shared among different users of the system like pharmacy personnel, medical center, health insurance, and emergency service.  
In WBAN, sensor nodes of a minimal size are usually implanted in or on the human body. The heat-rise of implanted sensors nodes and the energy consumption are the two significant challenges required to be dealt through efficient routing. As aforementioned, these WBAN enabled blockchain approaches did not consider the temperature-rise and energy-consumption for next-hop selection, which ultimately damages adjacent body tissues in case of continual transfer of physiological data. Moreover, none of the existing approaches minimized energy conservation to avoid frequent replacement of implanted nodes in WBAN. Additionally, many of the strategies discussed in the literature review are related to the management of health records or data sharing among different healthcare providers. Regardless, not any of the thermal/energy-aware approaches will address minimum heat-rise and maximize energy conservation in WBAN using hyperledger fabric. To the best knowledge of the author, there has been no functional routing protocol that is used to optimized heat-rise and energy conservation in WBAN based on blockchain to enhance network life-span built so far.