Basic Series-2| Concept of Staking

1. Starting Configurations

Validation node

* 4 at minimum and 100 at maximum.

* Validation nodes are responsible for packaging transactions and maintaining consensus on the chain.

Trust node (currently only Bitcoin Trust)

* 3 at least and 15 at most. ( Bitcoin Trust)

* The concept of a trust node is based on the inter-chain transfer bridge. Trust nodes often come at hand for hosting users’ inter-chain assets when ChainX light nodes cannot be integrated. Trust nodes are elected by ChainX’s validators in trust elections.

Dividend cycle

* 150 blocks, about 5 minutes.

* A certain number of PCXs are issued per dividend cycle.

Election cycle

* Official network: 12 dividend cycles, 1,800 blocks, about 60 minutes

Lock-up period for vote retraction

* Lock-up period for retracted votes: 72 election cycles, 3 days on the mainnet

* Lock-up period for redeemed nodes: 720 election cycles, 30 days on the mainnet

  • When a user retracts a vote from a node, PCXs involved are locked up for a period before return to the balance. After the period expires, the user can manually unlock the amount.

2. Basic concept

Dividend cycle rewards

A dividend cycle is analogous to one block of Bitcoin. A certain amount of PCXs are to be issued as rewards per cycle. Similar to Bitcoin, the total amount of PCX is 21 million, and the reward is halved every 210,000 dividend cycles, to put simply, 50 PCXs for the first 210,000 dividend cycles or the initial cycles, and 25 for the second round.

Node rewards distribution in dividend cycles

Team rewards

In the first 210,000 cycles, 20% of the 50 PCXs will be distributed to the team, which means the total rewards for all nodes in each cycle is 50 * 80% = 40 PCX. The reward cap to the team is 10% of the total, therefore, the team will only enjoy rewards in the initial cycles, and none afterwards.

Asset mining

Except for the 20% of the rewards that are handed out as dividends in the first 210,000 cycles, the rest are distributed through asset mining.

All participants in asset mining compete against each other in terms of their computing power with PCX as computing unit. Mining consists of two kinds: virtual computing power of inter-chain mining and real computing power of voting mining:

  • Inter-chain mining refers to all kinds of assets outside the chain like BTC and ETH that users transfer into the system through depositing, mapping or locking-up, that are automatically converted into the virtual PCX inter-chain mining power according to the price of the asset and the discount given to each asset. Every inter-chain asset has a different discount rate which could be adjusted through community voting. The reason why assets are discounted in value entering the chain is because PCX, as the system’s internal currency, should enjoy greater mining power than other inter-chain assets to encourage users to hold more PCX.
  • Voting mining means users that hold real PCX participate in the election of the PoS system and manually vote for certain nodes.

The total mining power of a user is equal to the inter-chain mining power of virtual PCX plus the voting power of the real PCX. For example, one user deposits one BTC, two ETHs into ChainX, and holds 700 PCXs among which 300 PCXs participate in the election and 400 PCXs do not. At the time, the exchange price in ChainX stands at 1BTC: 10000PCX, 1ETH: 1000PCX, and the user will automatically obtain the mining power of (1 * 10000 + 2 * 1000) * 10% + 300 = 1500PCX. All users have access to PCX mining revenue in each reward cycle according to the mining power they have. Users can use the PCX obtained through revenue to participate in elections or wait for the value of the inter-chain assets to go up to claim more mining power.

Node rewards

The system will calculate the rewards for each node according to the proportion of the total votes in each dividend cycle.

Node rewards = Votes of a node/ Total votes of all nodes * Total rewards

All nodes that are in the election and attract no less than 1 vote can access the rewards according to the number of votes they get over the total. A node that is forced off due to a previous offline penalty will not be able to receive rewards.

Note: Inter-chain assets participating in mining can be regarded as a virtual node which is yet part of the consensus, but could still receive rewards.

Node prize pool

Rewards are reallocated after being issued to nodes:

  1. 10% to the node account directly
  2. 90% to the node prize pool

The node prize pool is a special account that no one knows the private key. The calculating logic of the prize pool account:

Pool account = Hash (node ​​account)

The interest receivable by users in the prize pool is not automatically allocated, but needs to be calculated on the proportion of the user’s vote age to the total vote age of nodes when the user manually withdraws it.

Vote age

Vote age equals coin age in deposits mining, which also holds true for voting mining.

Node vote age

Each real node has the following attributes: total vote age, updated height of total vote age which is adjusted according to the total number of votes that nodes get when users cast or retract votes:

Total vote age = previous vote age +previous vote amount * (current height-previous updated height)Updated height of total vote age = current height

User vote age

Users have the following attributes: user vote age, updated height of user vote age, which is adjusted according to the total number of votes that nodes get when users cast or retract votes:

User vote age = previous user vote age + previous user votes * (current height-previous updated height)Updated height of user vote age = current height

Voting interest

If a user votes for a node, he or she can calculate the interest receivable after obtaining information about the node vote age and the current height:

Latest vote age = previous vote age + total voting amount * (current height-updated height)Latest user vote age = user vote age + voting amount * (current height-updated height)Interest receivable = latest user vote age / latest total vote age * amount in the prize pool

**Interest withdrawal **

A user withdraws his or her interest from the prize pool according to the proportion of the user’s vote age to the total vote age of nodes. After receiving the interest, the following changes occur to the vote age:

Total node vote age = total node vote age-user vote age
User vote age = 0

Node election

The validator nodes are elected every election cycle. Nodes that are qualified to stand the election must:

  1. already be a candidate
  2. attract at least 1 vote

Nodes that meet the above conditions can stand the validator node election and will be ranked according to the number of votes they get.

Original Resource

About ChainX



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ChainX is the largest Layer-2 network of Bitcoin, based on Substrate, and will evolve into the Polkadot Secondary Relay Chain.