A mining pool is a centralized or semi-centralized platform that allows miners from all over the world to aggregate the computing power of their devices. In Proof of Work-based networks, network security and transaction validation depend on solving cryptographic equations; a process in which computers search for a numerical discovery called a Nonce so that the block hash becomes lower than the target set by the network.

The Lottery Fund Analogy

To digest this mechanism, imagine a lottery ticket draw taking place where a lucky winner is determined once every ten minutes. If you buy a single ticket on your own, you might wait for centuries and never win. A mining pool is similar to an association where thousands of ticket buyers come together, throw all their tickets into a common fund, and commit that if any of the tickets win, the grand prize will be distributed among everyone based on the number of tickets each member purchased.

In the mining pool architecture, the pool server acts as the general manager. This server prepares the template or format of new blocks containing valid network transactions and distributes them to members along with a much simpler difficulty target. Instead of directly solving the entire Bitcoin network's equation, miners solve the simplified equations sent by the pool and return valid results to the server as "Shares." Sending these shares represents the actual and continuous activity of the mining device.

When one of the devices in the pool randomly produces a hash that meets not only the pool's simple target but also the extremely difficult target of the main blockchain, the pool broadcasts the block to the entire network. After the block is recorded and the network reward (including the block subsidy along with transaction fees) is received, this reward is distributed among all participants according to pre-determined formulas.

In the early days of Bitcoin's emergence, Satoshi Nakamoto and early activists were able to engage in solo mining using home computer CPUs. However, with the passage of time and the introduction of GPUs, FPGA chips, and eventually highly specialized ASIC (Application-Specific Integrated Circuit) devices such as the Bitmain Antminer S21 and the MicroBT Whatsminer M60, the network's hash rate has reached incredible figures exceeding 600 Exahashes per second (EH/s).

Numerical Scenario of Single-Device Miner Failure

Suppose a user has acquired a home mining device with a computing power of 200 Terahashes per second (TH/s). The total Bitcoin network hash rate is approximately 600 EH/s, which is equivalent to 600,000,000 TH/s. The computational share of this single-device miner would be one three-millionth of the total network power. Given that an average of 144 blocks are discovered on the network daily, from a mathematical probability standpoint, it would take an average of about 57 years for this device to discover a block on its own.

Even if this user keeps their device running for 57 years, due to the stochastic nature of the Poisson process in mining, there is no guarantee of discovering a block within this period, while depreciation costs and industrial electricity bills must be paid monthly. Consequently, the variance in solo mining returns is infinitely high, and its economic risk is capital-destructive.

Comparison Table: Solo Mining vs. Mining Pool

The following table shows the fundamental differences in operation and financial indicators between these two methods:

Mining pools distribute the revenue generated from block production based on various accounting mechanisms. These models determine whether the risk of block discovery variance falls on the pool operator or the member miners. Three dominant models in the current market are PPS, FPPS, and PPLNS.

Pay Per Share (PPS) model

In the PPS model, the pool immediately pays a fixed amount to the miner for every valid share they submit, regardless of whether the pool successfully discovers a new block on the network that day. In this method, all the risk of luck fluctuation lies with the pool, and for this reason, pools usually charge higher fees (around 3 to 5 percent).

Full Pay Per Share (FPPS) model

The upgraded version of the previous model is called FPPS, which is used in large pools such as F2Pool and Antpool. In the old PPS model, only the fixed block subsidy was distributed among miners, and transaction fees remained in the pool operator's pocket. However, in the FPPS model, the pool also calculates the average transaction fee rate on the network and pays it to the miner along with the base reward based on shares.

Pay Per Last N Shares (PPLNS) model

In the PPLNS method, payments only occur when the pool has actually discovered a valid block on the network. When a block is discovered, the system looks at a window of the N most recent registered shares and distributes the reward for that block among the miners who played a role in registering those shares. If the pool does not find any blocks in a 24-hour period, the miner's income will be zero; but if it finds several consecutive blocks, the profit becomes significant. Due to its much lower fee (around 1 percent), this model is the best option for loyal miners who do not constantly turn off or move their equipment.

The connection between hardware devices and the mining pool server is established through specific network protocols. The oldest and most widespread communication protocol is called Stratum V1. Despite its stability, the first version of Stratum has two fundamental flaws: high bandwidth consumption due to uncompressed text data, and the inability of miners to select the transactions present in a block.

Transition to the Stratum V2 Protocol

To counter the monopolistic control of pools over transaction selection, protocol developers launched the innovative Stratum V2 in collaboration with Braiins and open-source projects. This protocol not only encrypts communications and reduces farm bandwidth consumption but also allows individual miners to build their own transaction templates, preventing censorship at the level of the pool's central servers.

The 51% Threat and Hash Power Concentration

One of the serious engineering criticisms of mining pools is the risk of centralization. According to analytical statistics, a large portion of the Bitcoin network's computing power is held by a handful of large pools such as Foundry USA, Antpool, ViaBTC, and F2Pool. If only two or three large pools were to collude, they would theoretically be able to control more than 51% of the network's hash rate and rewrite transaction history or censor specific addresses; although the economic incentives and commercial reputation of these pools have prevented such destructive actions so far.

Golden Tips for Choosing a Mining Pool

• Alignment of Payment Model with Network Stability: If your budget cannot withstand daily income variance, prefer the FPPS model over PPLNS.
• Server Geographical Distance: Choose a pool whose servers have the lowest ping latency with your farm to minimize stale shares.
• Stratum V2 Compatibility: Using modern protocols helps with connection security, privacy preservation, and preventing hash rate poisoning attacks.

In your opinion, is the concentration of a major portion of the Bitcoin network's hash rate in three world-renowned pools a serious threat to the principle of blockchain decentralization, or will the economic incentives of miners to move capital quickly always prevent collusion? Write your views in the comments section.