A Survey of Layer-Two Blockchain Protocols. (arXiv:2204.08032v2 [cs.CR] UPDATED)

After the success of the Bitcoin blockchain, came several cryptocurrencies
and blockchain solutions in the last decade. Nonetheless, Blockchain-based
systems still suffer from low transaction rates and high transaction processing
latencies, which hinder blockchains' scalability. An entire class of solutions,
called Layer-1 scalability solutions, have attempted to incrementally improve
such limitations by adding/modifying fundamental blockchain attributes.
Recently, a completely different class of works, called Layer-2 protocols, have
emerged to tackle the blockchain scalability issues using unconventional
approaches. Layer-2 protocols improve …

blockchain protocols survey