[Paper Review] Speeding up Block Propagation in Blockchain Network: Uncoded and Coded Designs

Lihao Zhang, Taotao Wang+1 more|arXiv (Cornell University)|Jan 2, 2021

Blockchain Technology Applications and Security18 references4 citations

TL;DR

This paper proposes a novel block propagation protocol for Bitcoin that increases transaction throughput by 100x without altering consensus mechanisms. By combining cut-through forwarding and rateless erasure coding with compact-block relaying, it reduces block propagation latency even for large blocks, maintaining security and enabling seamless integration into existing blockchain networks.

ABSTRACT

We design and validate new block propagation protocols for the peer-to-peer (P2P) network of the Bitcoin blockchain. Despite its strong protection for security and privacy, the current Bitcoin blockchain can only support a low number of transactions per second (TPS). In this work, we redesign the current Bitcoin's networking protocol to increase TPS without changing vital components in its consensus-building protocol. In particular, we improve the compact-block relaying protocol to enable the propagation of blocks containing a massive number of transactions without inducing extra propagation latencies. Our improvements consist of (i) replacing the existing store-and-forward compact-block relaying scheme with a cut-through compact-block relaying scheme; (ii) exploiting rateless erasure codes for P2P networks to increase block-propagation efficiency. Since our protocols only need to rework the current Bitcoin's networking protocol and does not modify the data structures and crypto-functional components, they can be seamlessly incorporated into the existing Bitcoin blockchain. To validate our designs, we perform analysis on our protocols and implement a Bitcoin network simulator on NS3 to run different block propagation protocols. The analysis and experimental results confirm that our new block propagation protocols could increase the TPS of the Bitcoin blockchain by 100x without compromising security and consensus-building.

Motivation & Objective

• To address the low transaction throughput (TPS) in Bitcoin and Ethereum, which limits real-world adoption despite strong security.
• To increase TPS without modifying the consensus protocol or data structures, preserving blockchain security and privacy.
• To reduce block propagation latency when transmitting large blocks, which otherwise increases stale-block rates and compromises security.
• To design a scalable, backward-compatible networking protocol that can be deployed in existing blockchain networks.

Proposed method

• Replacing the store-and-forward compact-block relaying scheme with a cut-through forwarding mechanism to enable parallel reception and forwarding of block chunks.
• Introducing rateless erasure codes to allow peers to reconstruct source blocks from any subset of encoded symbols, improving resilience and bandwidth utilization.
• Designing a Coded Cut-through Compact Block Relaying (Coded Cut-through CBR) protocol that combines cut-through forwarding with rateless coding for maximum efficiency.
• Using a theoretical linear network model to analyze protocol performance and validate design assumptions.
• Implementing a full Bitcoin network simulator in NS3 to evaluate latency, stale-block rates, and propagation divergence under various block sizes and protocols.
• Evaluating four protocols: Standard Relay (SR), Compact Block Relay (CBR), Cut-through CBR, and Coded Cut-through CBR across block sizes from 1 MB to 100 MB.

Experimental results

Research questions

• RQ1 Can cut-through forwarding reduce block propagation latency compared to store-and-forward and compact-block relaying in large-block scenarios?
• RQ2 To what extent can rateless erasure coding improve block propagation efficiency in P2P blockchain networks?
• RQ3 Can the combination of cut-through forwarding and rateless coding maintain low propagation latency even when block size increases by 100x?
• RQ4 How does the propagation divergence factor and stale-block rate scale with increasing block size under different relaying protocols?
• RQ5 Can the proposed protocol achieve 100x higher TPS without modifying the consensus mechanism or data structures?

Key findings

• Cut-through CBR reduces median block propagation latency by up to three times and tail latency by over 100 times compared to standard relay (SR) when propagating 100 MB blocks.
• Coded Cut-through CBR reduces median and tail latency by up to two times compared to Cut-through CBR across different values of k (code rate).
• The propagation divergence factor Δ for Coded Cut-through CBR with optimal k remains at the level of SR at 1 MB block size, even when block size increases to 100 MB.
• The stale-block rate increases by approximately 30x for CBR when block size increases from 1 MB to 100 MB, but remains low for Coded Cut-through CBR, preserving security.
• The proposed protocols enable a 100x increase in TPS while maintaining the same propagation delay as the original 1 MB block protocol, without altering consensus or data structures.
• The simulation results confirm that the new protocols are scalable, secure, and compatible with existing Bitcoin networks, enabling deployment without protocol-level changes.