Optimizing Peer Selection for Performance Enhancement of Bitcoin Peer-to-Peer Network

Jamal, Mohd Saalim and Kataoka, Kotaro (2019) Optimizing Peer Selection for Performance Enhancement of Bitcoin Peer-to-Peer Network. Masters thesis, Indian institute of technology Hyderabad.

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Abstract

In the Bitcoin network, the current block interval time of 10 minutes and the maximum block size of 1MB leads to a low transaction throughput compared to visa and other payment methods. Decreasing the block interval time or increasing the block size may increase the probability of inconsistency, leading to frequent blockchain fork in the Bitcoin network. This work attempts to decrease the block interval and increase the block size without hampering the network with excessive forking. It investigates the peer selection technique of the Bitcoin network for improving its performance. Instead of random peer selection as per the current Bitcoin protocol, it studies the effect of improved peer selection using link information on the performance of the Bitcoin network using a real-time testbed created with Bitcoind [4] client. An efficient peer-to-peer network formed by choosing the optimum peers helps to alleviate the frequency of forking even with a low block interval time and high block size. Geographical location based peer selection [1] and low-latency based peer selection [2] provides a better network formation, but their effect on mean propagation delay, transaction throughput, and stale block rate has not been studied. This work explored various techniques for selecting peers to form the peer-to-peer network. All Pair Shortest Path based and network partition using community detection are explored with a view of optimizing the network globally. A local view of optimizing the network formation considering the particular node is also investigated. This work then proposes to choose peers based on a linear combination of both latency and bandwidth since bandwidth also plays an important role when block size increases. The proposed algorithm generates a score for all the peers received either by DNS seed or by peer discovery mechanism and chooses the top scored peers. Simulation results based on the Bitcoin Simulator [3] show a reduction of about 60-70% in mean propagation delay, 30-35% in stale block rate and an increment of 20-25% in transaction throughput over the original Bitcoin protocol even with a small block interval time of 30 second and high block size of 2MB. The state-of-art BCBPT [2] algorithm is also implemented for the comparison. In addition to this, the practical operation of the proposed approach in the actual Bitcoin network is also discussed. The expected overhead incurred in applying the algorithm in the network is also stated along with the possibility of overhead reduction by the appropriate parameter adjustments.

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