Motivation
BTTC currently submits checkpoints to 3 mainchains (Tron, Ethereum, BSC) every 30 minutes for verifying cross-chain transactions on the mainchains. Submitting checkpoints to mainchains generates transactions and thus transaction fees on those chains. Since there are currently few cross-Ethereum transactions on BTTC, usually only once every few hours, the current 30 minute submission frequency results in many useless submissions without actual cross-chain transactions. Considering Ethereum’s relatively high transaction fees, this causes significant waste in transaction fees.
Specification
In order to reduce useless submissions to Ethereum and save transaction fees incurred by checkpoint submissions, we plan to modify the current “fixed 30 minute submission” strategy to “check every 30 minutes, submit only when there are cross-chain transactions, also submit if no cross-chain transactions but more than 4 hours since last submission”.
Upgrade Description: Hard fork upgrade
Proposal Activation: Activated through on-chain proposal (details to be finalized and proposed later)
Expect Effect
Transaction Fee Savings
After adjustment, the estimated number of checkpoint submissions to Ethereum per week is expected to decrease by approximately 70% (based on on-chain data from the past 6 months). This reduction will depend on actual transaction volume and timing. The decreased submissions will result in estimated fee savings of around 70% (not considering price fluctuations).
Validator Reward Effects
Currently, all validators receive equal checkpoint submission rewards (10% of total rewards). After adjustment, submissions will happen randomly - when cross-chain transactions occur or 4 hours elapse since last submission. This introduces some variability in validator submission opportunities and associated rewards. In the extreme case, all submissions could be performed by one validator, concentrating that portion of rewards. However, the overall impact is capped at 10% of total rewards. If we assume cross-chain transactions occur randomly, all validators will have equal probability of submissions over time, resulting in no systematic reward inequality.
Overall expectation
Although the adjustments may cause up to 10% imbalance in on-chain reward distribution, based on current transaction data, it can significantly reduce validators’ checkpoint submission costs and be overall beneficial to validators.
If subsequent coin price fluctuations or other factors lead to more pronounced uneven reward distribution, this strategy can be disabled via proposal to revert back to previous 30 minute fixed submissions.