Asynchronous Byzantine reliable broadcast receives renewed attention recently, as it is fundamental to many faulttolerant critical applications. This paper focuses on the Byzantine Reliable Broadcast protocol, which was first proposed by Bracha in 1987. Several recent protocols have improved the round and bit complexity of these algorithms. Motivated by practical network constraints in modern applications, this paper revisits the problem and reduces both complexity in communication and local computation. State-of-the-arts protocols are evaluated using the developed framework that simulates realistic bandwidth constraints. The evaluation demonstrates that our protocols, which use cryptographic hash functions and erasure coding in a novel way, have superior performance in critical applications such as asset transfer and smart home.

Industry 5.0 is emerging as a result of the advancement in networking and communication technologies, artificial intelligence, distributed computing, and beyond 5G. Among the important enabling technologies, federated learning, industrial edge computing, and Byzantine-tolerant machine learning (ML) are key accelerators in Industry 5.0. We propose a framework to integrate these key components. Recent works have designed various Byzantine-tolerant ML algorithms for a datacenter or a cluster. However, these algorithms are difficult to be applied to industrial edge computing paradigms. In this article, a novel Byzantine-tolerant federated learning algorithm, CRACAU, is designed for the popular three-level edge computing architecture. In this algorithm, edge devices jointly learn an ML model using the data collected at each device, and their private data are never shared with others. Under standard assumptions, we formally prove that CRACAU converges to the optimal point, i.e., CRACAU finds the optimal parameters of the ML model. We also implement CRACAU in the MXNet framework and evaluate it on the popular benchmark MNIST and CIFAR-10 image classification datasets. Experimental results show that CRACAU achieves satisfying accuracy.

We introduce Rabia, a simple and high performance framework for implementing state-machine replication (SMR) within a datacenter. The main innovation of Rabia is in using randomization to simplify the design. Rabia provides the following two features: (i) It does not need any fail-over protocol and supports trivial auxiliary protocols like log compaction, snapshotting, and reconfiguration, components that are often considered the most challenging when developing SMR systems; and (ii) It provides high performance, up to 1.5x higher throughput than the closest competitor (i.e., EPaxos) in a favorable setup (same availability zone with three replicas) and is comparable with a larger number of replicas or when deployed in multiple availability zones.

Recent works have proposed various distributed federated learning (FL) systems for the edge computing paradigm. These FL algorithms can assist pervasive applications in various aspects, e.g., decision making, pattern recognition, and behavior prediction. Existing solutions do not efficiently support the training based on the real-time location-specific data, because fundamentally, the "data collection" problem is rarely studied in the context of FL systems. To address this problem, we present a novel system, VC-SGD (Vehicular Clouds-Stochastic Gradient Descent), which seamlessly integrates the emerging concept of vehicular clouds with an edge-based FL. We show that by using vehicular clouds as virtual edge servers, VC-SGD is able to effectively support FL algorithms that use real-time location-specific data. We develop a general simulator that uses SUMO to simulate vehicle mobility and MXNet to perform real training. We use our simulator to verify the efficacy of VC-SGD. The experimental results demonstrate that VC-SGD improves over existing solutions.

ABSTRACTThis paper presents CarML, a distributed machine learning platform built on top of an emerging computing paradigm, vehicular clouds. We discuss our design and technical challenges, followed by our preliminary solutions. We verify the efficacy of our solutions using a customized simulator based on Python and SUMO.