Vega: An Asynchronous BFT With Lower Communication Overhead and Lower Latency

The low-altitude economy has experienced significant growth recently, due to the flexibility, affordability, and versatility of low-altitude aircraft. A typical setup uses multiple devices in a distributed system, where theByzantine Fault Tolerance(BFT) consensus ensures data consistency. However, existing BFT protocols, such as those based on the BKR paradigm with HoneybadgerBFT as a representative, suffer from high communication overhead and latency, limiting scalability and performance. In this paper, we introduce Vega, a novel BFT protocol designed to overcome these challenges. Vega replaces the traditionalReliable Broadcast(RBC) protocol with a more efficient linearConsistent Broadcast(CBC), reducing communication overhead from$O(n^{3})$to$O(n^{2})$. However, this change introduces a new challenge related to totality, which may impact liveness. Additionally, Vega incorporates a fast path for block agreement, which reduces agreement latency to two communication rounds under optimistic conditions, with a fallback to the originalAsynchronous Binary Agreement(ABA) in less favorable cases. However, this introduces another challenge: ensuring consistency between blocks committed via the fast and normal paths. To solve these challenges, we introduce a block retrieval mechanism and apreparationstep, ensuring both liveness and consistency. Our experimental results show that Vega significantly outperforms existing protocols, reducing latency by up to 45% and achieving up to 1.8x higher throughput compared to HoneybadgerBFT.