Rewards

Introduction to Map chain epoch rewards and the target reward release schedule.

What are Epoch Rewards?

Epoch Rewards are similar to the familiar notion of block rewards in other blockchains, minting and distributing new units of MAP as blocks are produced, to create several kinds of incentives.

Epoch rewards are paid in the final block of the epoch and are used to:

1. Distributed rewards for validators

2. Distribute rewards to holders of Locked MAP voting for validator that elected validators

3. Make payments into a Community Fund for protocol infrastructure grants

Each epoch will be rewarded with a fixed reward.

• First 2 years, EpochReward= 833,333 MAP.

Reward Disbursement

The amount of disbursements is determined at the end of every epoch via a three step process.

Step 1

In step one，Community Fund will receive a fixed percentage of the reward

• CommunityFundReward = CommunityFundMultiplier*EpochReward

• CommunityFundMultiplier default value = 0.

Step 2

In step two,we will Count the number of signatures of each validator and convert it into a score(Sorce>=0,<=1), which will eventually participate in the calculation of rewards.

If the validator fails to fulfill its responsibilities, it will be punished through the punishment mechanism.

So per validator will receive the reward:

• ValidatorReceived = (EpochReward-CommunityFundReward) * StakingWeight * OwnActiveVotes / TotalActiveVotes + WorkWeight * OwnScore / TotalScores.

• StakingWeight Staking weight of validator(StakingWeight>0, StakingWeight<=1, default value is 1)

• WorkWeight Work weight of validator(WorkWeight = 1 - StakingWeight).

• OwnActiveVotes The number of votes activated by the current validator.

• TotalActiveVotes The active votes received across all validators.

• OwnScore The score obtained by the current validator. Your node online time will directly affect this parameter. If you have this parameter smaller than other validators, you will be penalized, which will slashing your reward. (0 <= OwnScore <= 1)

• TotalScores The sum of the scores of all validators.

The score is calculated by this formula:

• NewScore = UptimeScore * AdjustmentSpeed+OldScore * (1 - AdjustmentSpeed)

• UptimeScore This is score of work done at TotalMonitoredBlocks.

  • The TotalMonitoredBlocks are the total number of block on which we monitor uptime for the epoch.

  • TotalMonitoredBlocks value range is [EpochFirstBlock + lookbackWindowSize(defult = 12) -1,EpochLastBlock - BlocksToSkipAtEpochEnd(defult = 2)]

  • lookbackWindowSize A fixed value about lookbackWindow check whether the validator has signed in a fixed interval.

  • If you have a successful sign in [NowBlockNumber-lookbackWindow ,NowBlockNumber], we will regard your current block as a successful work.

  • BlocksToSkipAtEpochEnd represents the number of blocks to skip on the monitoring window from the end of the epoch

    • About currently we skip blocks:

    • lastBlock => its parentSeal is on firstBlock of next epoch

    • lastBlock - 1 => parentSeal is on lastBlockOfEpoch, but validatorScore is computed with lastBlockOfEpoch and before updating scores

    • (lastBlock-1 could be counted, but much harder to implement)

  • About first block to monitor:

    • we can't monitor uptime when current lookbackWindow crosses the epoch boundary.

    • thus, first block to monitor is the final block of the lookbackwindow that starts at firstBlockOfEpoch.

  • So UptimeScore = SignedBlocks / TotalMonitoredBlocks.

    • SignedBlocks Number of blocks signed by validator,this will be checked every time the block is produced.

    • First, check whether the current block is in BlocksToSkipAtEpochEnd.

    • Second, check whether the current block review period is signed. If it exists, the signature will be regarded as successful

    • if First step and Second step is successful SignedBlocks will add 1.

• AdjustmentSpeed A adjustment factor.This way will encourage the validator to stabilize.('AdjustmentSpeed' default value is 0.2).

• OldScore. This is the score of the last epoch of this validator.(In the fist distribute epoch reward OldScore is 0)

Step 3

In step three, because the validator will distribute the reward to voter, the actual validator will receive the reward:

• ValidatorActualReceived =ValidatorReceived * Commission * OwnScore.

• Commission A proportional value drawn by the validator in proportion to the ValidatorReceived.

The validator's voters will receive:

-VotersReward = ValidatorReceived - ValidatorActualReceived.

These rewards(VotersReward) will be returned to the voting pool. This operation is equivalent to an increase in the number of votes per voter. Voters draw their votes from the voting pool and get corresponding rewards.

Per voter's reward will be obtained according to the voting proportion of voter to validator.

Expand:

case One: Validator was deRegister during his service.

In this case,we won't consider him when awarded,the rest validators will share his reward equally.

case Two: Validator Re register.

When a validator is deRegistered, voters can still cancel the votes on the deRegistered validator as they wish.

If voter don't withdraw his vote,voters vote will remain in the voting area,Wait for the validator to register again, and these tickets will be returned to the validator again.

Implementation

EpochRewards.sol manages calculating epoch rewards.