The Taub Faculty of Computer Science Events and Talks

In blockchain applications, transaction latency is a key factor in the quality of service (QoS). Each application that uses the blockchain network has the motivation to reduce the latency for its own transactions. The block proposer selects which pending transaction to include in the proposed block and would like to prioritize its own application transactions over those of other applications. To maintain fairness, a block proposer can be asked to select the transactions randomly among pending transactions it is aware of. The random selection might imply high variance of the latency such that some transactions wait a long time before included in the chain. We present an alternative, age-aware approach towards fairness so that transaction priority is increased upon observing a large waiting time. It can be challenging to validate some transaction age since the age of a transaction is not absolute and a node might present its transactions as older to obtain priority. We consider various network restrictions on transaction propagation and explain how to enhance fairness in each one of them. In a general case, we present usage of declaration schemes in which a node efficiently declares its pending transactions providing the ability to validate transaction age. We demonstrate the advantages of our approach in reducing the tail latency on Ethereum and synthetic data.