## 4 Implementation and Discussion
### Performance Analysis
#### 4.2.11 Comparison with a Few Other Consensus Algorithms  
Several consensus gathering algorithms are studied during PoF designing. Now, a theoretical comparison of PoF with existing consensus algorithms is presented (Table 5) based on the performance metrics of Hyperledger [81]. How the proposed PoF based collaborative medical decision gathering system is qualitatively superior to existing consensus gathering algorithms is elaborated here (based on the factors mentioned in Table 5):* Node management: In between the consortium and permissionless blockchain, consortium blockchain is more controlled by the peers and allows comparatively easy modification of block information. If blockchain nodes are limited, identities of blockchain nodes can also be anonymous. Therefore, the proposed method chooses the consortium system for efficient node management. However, PBFT [37] and Tendermint [40] assess identities of the available nodes during a consensus mechanism. Alternatively, most of the permissionless consensus (PoW [35], PoS [38], and Ripple [39]), nodes are able to join the network without any identity verification [82]. * Transmission rate: The proposed system experiences a higher transmission rate for three reasons. Firstly, this scheme is a consortium blockchain with a limited number of nodes, so consensus gathering needs reasonably less time. Secondly, the use of off-the-chain data storing architecture also reduces the overall block size. Finally, Multichain [79] allows for the configuration of block size and block time, so the overall throughput increases in the proposed scheme by many times. Alternatively, PoS encourages the owner of the coin to prolong the coin holding time [83], so it also experiences a slightly higher transmission time. Similarly, as PBFT needs several transactions among peers before approving a block, transaction time is also high like Ripple [84]. As PoW demands higher node performance, the overall bottleneck increases [82]. Similarly, Ripple needs to wait till 80% are in agreement, and it also needs a higher transaction time [82]. On the other hand, the proposed PoF based collaborative demands 75% agreement (which is also changeable). * Energy consumption: In PoW, mining reward depends on the amount of work done, so the computer system of the miners consumes higher energy. Compared to PoW, PoS consensus gathering algorithm requires less energy but is still high [82]. Alternatively, the proposed system (PoF) consumes less energy, as no reward system is available on work. * Scalability: As PoW and PoS have higher energy consumption rate and block size, they preserve a higher scalability issue. PoS improved scalability by achieving better latency with a smaller block size [84]. Alternatively, due to off-the-chain data storing facilities and lower block size, the proposed PoF based collaborative system is highly scalable [85]. PBFT, Ripple, and Tendermint also face lower scalability to the existing system for network bottleneck [85]. * Finality process: Unlike the PoW, PoS, Ripple, and Tendermint blockchain consensus algorithm, PoF follows an immediate or absolute finality process. That is, just after the agreement from decision giving entities a new block with the collaborative medical decision is created. Alternatively, most consensus algorithms (PoW, PoS, Ripple, and Tendermint) follow a probabilistic finality process that waits until a certain period before a block gets finalized [82]. However, real-world business also demands immediate finality, as no one wants to take the risk of losing assets during the waiting time [82,84]. * Adversary tolerated power: Adversary tolerated power states the amount of control an attacker must have to regulate a blockchain network. A node in PoW needs at least 25% computer power to manipulate or create a block. Similarly, an attacker needs to control over 51% (more than half) of the stakes to control over the blockchain [84]. In comparison to those, the proposed PoF restricts adversary tolerated power to 75%.