Hybrid tip selection algorithm in IOTA

Abstract

Distributed Ledger Technology (DLT) refers to the technical architecture that enables simultaneous access, validation, and record of transactions in an immutable way over a network. IOTA is a distributed ledger developed to record and send transactions between nodes in the Internet of Things (IoT) design. Node is an electronic device that can create, receive, or transmit transactions over the IOTA network, known as the tangle. Every node in IOTA wants to submit a transaction. The network will allow nodes to submit their transaction, only after they run the Tip Selection Algorithm (TSA). TSA is an essential part of the IOTA tangle. The term "tips" refers to transactions that are still waiting to be approved by other nodes. The unverified transactions are called orphan tips, meaning that orphan transactions are not approved by any node. Nodes in the tangle that approve older transactions are called lazy nodes, and transactions submitted by lazy nodes are called lazy tips. There should be a trade-off between verifying a transaction (orphan) and how quickly a transaction is verified (lazy tips). The importance of the TSA is to balance the number of orphan transactions and lazy tips. Our contribution in this thesis is to make adjustments in the TSAs by assigning adaptive values for the TSAs. Parameter α is a determining factor in the TSA algorithms to adjust the number of lazy and orphan tips. In this thesis, we propose a new hybrid TSA algorithm. The hybrid TSA employs a recursive walk with a variable α parameter. In the experimental analysis of the thesis, we measured the orphan and lazy tips for different TSA algorithms from the output data generated by the IOTA simulator. The result shows that the hybrid TSA can effectively eliminate the number of lazy tips