Chien-Fu Cheng

Byzantine Agreement on Mobile Ad-Hoc Network

Mobile Ad Hoc Network (MANET) has been more and more popular. MANET is a self-organizing, self-configuring and instantly deployable multi-hop wireless network in response to application needs without any fixed infrastructure. Moreover, the fault-tolerance and reliability of the MANET has also been an important topic. Toward this goal, we need a mechanism to allow a set of nodes to agree on a common value. The distributed Byzantine Agreement (BA) problem is one of the most important issues to take into consideration in designing a fault-tolerance system. In many cases, reaching a common agreement among fault-free nodes to cope with the influence from faulty components is crucial in a fault-tolerance system. In this study, the BA problem is visited in a MANET, in which the components may be subject to malicious fault.

The anatomy study of server-initial agreement for general hierarchy wired/wireless networks

The Byzantine Agreement (BA) plays a key role in fault-tolerant distributed system design. A number of solutions to the BA problem based on various network model assumptions have been proposed. However, most existing BA protocols are designed for pure wired or pure wireless networks. In practice, most current networks are combined wired and wireless environments. In this paper, we extend the BA problem over a combined wired/wireless network, consisting of both powerful computing stationary processor and low-power mobile processor. The communication overhead of BA protocol is inherently large and secure group communications are important. The protocols proposed in this paper use the hierarchical model concept to reduce the communication overhead and provide secure group communications well suited for combined wired/wireless networks.

Multi-agent schema of Mobile IP protocol for mobile environment

Mobile communication has been more and more popular not only because it supports convenient wireless communication within networks but also due to the powerful roaming function among networks without disconnection. In conventional mobile communication designs, there is usually only one single Mobile Agent (MA) in one network, which means the whole network would go out of control once MA fails in the network Another drawback is that each MA and node in the network should maintain the binding information in its own cache. However, ask every node to store and maintain the binding information in its cache is a heavy burden. In this study, the proposed Fault-tolerant Multi-agent based Mobile IP (FMIP) schema, which can solve the above drawbacks of single MA in one network by using the multi-agent based model to provide fault-tolerant capability. In addition, we also solve the drawback of each node should maintain the binding information in its own cache by maintaining the Mobile Agent Table (MAT) and Binding Update Table (BUT) in the MA only. Finally, we shall also provide the Smooth Handoff mechanism, Take Over mechanism, and Recovery mechanism for the mobile environment to provide the powerful fault-tolerant capability.

Reaching agreement on an unknown network with partial graphic information

The Byzantine Agreement (BA) is an important topic in the reliable distributed system because the system can cope with the influences from faulty components when the agreement is achieved. In the literature concerned, the BA problem has been well formulated in a Fully Connected Network (FCN) and a Generalized Connected Network (GCN) under the assumption that each processor in the network has the common knowledge of the graphic information about the entire network structure. However, in the real world, each processor may not have the common knowledge of the graphic information about the entire network structure. That is, the processors may only have the partial knowledge as to their own graphic information. In this paper, the Byzantine Agreement problem will be visited in an Unknown Network (UNet) to increase the capability of fault tolerance by allowing faulty processors with dual failure mode. The proposed protocols, the Unknown Agreement Protocol (UAP) and the Relay Channel (RC), use the minimum number of rounds of message exchange and can tolerate the maximum number of faulty processors allowed.

Server-Initiated Byzantine Agreement over Two-Level Combined Wired/Wireless Networks

In previous results, most existing Byzantine agreement (BA) protocols are designed for pure wired or pure wireless networks. In practice, most current networks are combined wired and wireless environments. In this paper, we extend the BA problem over combined wired/wireless network, consisting of both powerful computing processor and low-power mobile processor. Furthermore, the communication overhead of the BA protocol is inherently large because the BA protocol requires numerous rounds to exchange messages. Secure group communications over a combined wired/wireless network is very important. The protocols proposed in this paper use the hierarchical model concept to reduce the communication overhead and provide secure group communications well suited for combined wired/wireless networks

Zone-Oriented byzantine agreement on zone-based wireless ad-hoc network

A wireless ad-hoc network system may suffer from various types of hardware failure. In order to enhance the fault-tolerance and reliability of the wireless ad-hoc networks, we revisit the Byzantine Agreement problem in the zone-based wireless ad-hoc network in this paper. The proposed protocol is called as the Zone-Oriented Agreement Protocol (ZOAP) which can make each fault-free mobile processor reach an agreement value to cope with the faulty component in the zone-based wireless ad-hoc network.