Bitcoin's 1 megabyte block size constrains capacity for small payments. With mempools in the range of 50 million to 100 million bytes, settling a $1 transaction on the main chain becomes unfeasible. T
Bitcoin's 1 megabyte block size constrains capacity for small payments. With mempools in the range of 50 million to 100 million bytes, settling a $1 transaction on the main chain becomes unfeasible. Transaction fees erode the micropayment value proposition.
Over the past two years, bitcoin developers across open-source initiatives and commercial firms have championed second-layer solutions. Lightning Network and comparable payment channels operate above the base blockchain, batching together small transactions the way a restaurant bill accumulates throughout an evening. A hundred separate transactions might collapse into a single on-chain settlement.
Wallet providers and exchanges have lagged on adoption despite widespread discussion. A recent working paper by Christian Decker of Blockstream, Roger Wattenhofer, and Conrad Burchert from ETH Zurich addresses a critical limitation: locked capital.
Payment channels require participants to deposit funds into shared accounts. As more channels proliferate, the on-chain footprint grows. The researchers identified two constraints: blockchain capacity and locked-in funds. They wrote: "Micropayment channel networks create new problems, which have not been solved in the original papers. We identify two main challenges - the blockchain capacity and locked-in funds. Even with increases in block size it was estimated that the blockchain capacity could only support about 800 million users with micropayment channels due to the number of on-chain transactions required to open and close channels."
The paper proposed hiding channels from the main blockchain. Keeping them off-chain reduces the burden on the base layer. "For a group of 20 nodes with 100 channels in between them, this can save up to 96% of the blockchain space," they wrote.
The research demonstrated that second-layer payment channels can be deployed on existing platforms, offering an alternative to heavy blockchain settlement. What happens next depends on SegWit adoption. If the upgrade gains traction, exchanges and wallet companies will probably begin offering these channels to customers, reducing transaction fees and processing times.
A previous version of this article stated that Conrad Burchert and Roger Wattenhofer worked for Blockstream. Both researchers are affiliated with ETH Zurich.
