All-to-all communication with low communication cost

Abstract

In an all-to-all broadcast, every user wishes to broadcast its message to all the other users. This is a process that frequently appears in large-scale distributed systems such as voting and consensus protocols. In the classic solution, a user needs to receive n messages and n signatures where n is the number of users in the network. This is undesirable for large-scale distributed systems that contain millions or billions of users and can be the throughput bottleneck for some existing systems. In this thesis, we propose two protocols for the all-to-all broadcast problem. Our protocols upper bound the number of bits each user receives by [Theta](n log log2 n), which is a huge improvement from the conventional n times the signature size. Besides the all-to-all protocol, we also provide new results regarding random graphs and regular graphs. These results are used in our protocol to prove its efficiency. But they are interesting by themselves and have independent theoretic value.