Tony Mak

Bio: Tony Mak is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Dedicated short-range communications & Quality of service. The author has an hindex of 13, co-authored 21 publications receiving 1497 citations. Previous affiliations of Tony Mak include Toyota Motor Engineering & Manufacturing North America & University of California.

Vehicle-to-vehicle safety messaging in DSRC

Abstract: This paper studies the design of layer-2 protocols for a vehicle to send safety messages to other vehicles. The target is to send vehicle safety messages with high reliability and low delay. The communication is one-to-many, local, and geo-significant. The vehicular communication network is ad-hoc, highly mobile, and with large numbers of contending nodes. The messages are very short, have a brief useful lifetime, but must be received with high probability. For this environment, this paper explores the efficacy of rapid repetition of broadcast messages. This paper proposes several random access protocols for medium access control. The protocols are compatible with the Dedicated Short Range Communications (DSRC) multi-channel architecture. Analytical bounds on performance of the proposed protocols are derived. Simulations are conducted to assess the reception reliability and channel usage of the protocols. The sensitivity of the protocol performance is evaluated under various offered traffic and vehicular traffic flows. The results show our approach is feasible for vehicle safety messages in DSRC.

A Multi-channel VANET Providing Concurrent Safety and Commercial Services

Abstract: One of the key goals of a vehicular ad-hoc network (VANET) is providing sufficient quality of service (QoS) for real-time safety applications while concurrently supporting commercial services. This paper proposes a multi-channel wireless communication architecture and protocol for the scenario where commercial services are provided by roadside infrastructure. This solution extends the IEEE 802.11 wireless LAN protocol to schedule periodic safety messages in a safety channel . It explicitly supports concurrent non-time-critical communications in separate, non-safety service channels . Further, it is shown that this arrangement maximizes service channel access time while maintaining the requisite QoS for safety applications. This paper concludes with simulations that confirm the attractive properties of this architecture and protocol.

A multi-channel VANET providing concurrent safety and commercial services

Abstract: In this paper, we propose a medium access control (MAC) protocol to support the multi-channel operation for dedicated short range communication (DSRC). In particular, we focus on the challenge of providing potentially high-bandwidth for non-safety applications provided by roadside infrastructure, without compromising safety communication occurring in a separate channel. In our architecture, when a vehicle approaches a DSRC service hot-spot, it switches from the ad-hoc mode to the coordinated mode (and switches back to ad-hoc as it leaves the hotspot's range). This coordinated mode is a variant of IEEE 802.11 PCF, modified for multi-channel operation. The coordinated mode maximizes utilization of the DSRC "service channels" in the DSRC hot-spots while allowing safety-message broadcasts to be received with high probability in a distinct "safety channel". When a vehicle is not within the range of a DSRC hot-spot, the vehicle can use any of the previously-proposed ad-hoc protocols. Our approach can use any of these ad-hoc protocols for its ad-hoc mode. The MAC protocol is simulated with realistic mobility trace, and verified that it meets our safety and service objectives.

Medium Access Control Protocol Design for Vehicle–Vehicle Safety Messages

Abstract: We propose a medium access control protocol design for a vehicle to send safety messages to other vehicles. We develop a Quality-of-Service (QoS) model for safety messages that are consistent with the active vehicle safety systems literature. Each message has a range and useful lifetime. The QoS target has each message received with high probability within its specified lifetime by each vehicle within its specified range. The protocol design is based on rapidly rebroadcasting each message multiple times within its lifetime in combination with the 802.11 Distributed Coordination Function. This makes the design compatible with emerging standards for Dedicated Short-Range Communication. Six different design variations are proposed. We derive equations and develop a simulation tool to assess the performance of the designs. Using these, we identify the best and most easily implemented designs. Design performance depends on the number of rebroadcasts, power, modulation, coding, and vehicular traffic volumes. We show that under certain assumptions on the loss probability tolerated by safety applications, the design is able to transport safety messages in vehicular ad hoc networks

Multi-Channel Medium Access Control for Dedicated Short Range Communications

Abstract: This paper describes a medium access control (MAC) protocol to enable multi-channel operation for dedicated short range communication (DSRC). In particular, the authors focus on the challenge of supporting potentially high-bandwidth commercial or infotainment communications between vehicle and roadside in hotspots over several service channels, while concurrently enabling time-critical vehicle-vehicle communication for safety in a separate channel. In our architecture, within hotspots, communication is aided by one of the access points in the hotspot. This access point is designated the Coordinating Access Point (CAP). Outside hotspots, communication is for safety and is conducted in an ad-hoc fashion. The CAP protocol design is a variant of IEEE 802.11 PCF, modified for multi-channel operation. The design objective is to maximize utilization of the service channel used for non-safety communication while meeting the Quality of Service (QoS) constraints of the safety communications. The performance of 802.11 DCF, PCF, and the CAP extension is quantified by simulation in NS-2. The mobility model represents a 4-lane freeway at maximum vehicular traffic flow derived from the SHIFT traffic simulator. The CAP design is shown to significantly enhance both safety and non-safety communication relative to DCF and PCF only.

Securing vehicular ad hoc networks

Abstract: Vehicular networks are very likely to be deployed in the coming years and thus become the most relevant form of mobile ad hoc networks. In this paper, we address the security of these networks. We provide a detailed threat analysis and devise an appropriate security architecture. We also describe some major design decisions still to be made, which in some cases have more than mere technical implications. We provide a set of security protocols, we show that they protect privacy and we analyze their robustness and efficiency.

A tutorial survey on vehicular ad hoc networks

Abstract: There has been significant interest and progress in the field of vehicular ad hoc networks over the last several years. VANETs comprise vehicle-to-vehicle and vehicle-to-infrastructure communications based on wireless local area network technologies. The distinctive set of candidate applications (e.g., collision warning and local traffic information for drivers), resources (licensed spectrum, rechargeable power source), and the environment (e.g., vehicular traffic flow patterns, privacy concerns) make the VANET a unique area of wireless communication. This article gives an overview of the field, providing motivations, challenges, and a snapshot of proposed solutions.

Vehicular Networking: A Survey and Tutorial on Requirements, Architectures, Challenges, Standards and Solutions

Abstract: Vehicular networking has significant potential to enable diverse applications associated with traffic safety, traffic efficiency and infotainment. In this survey and tutorial paper we introduce the basic characteristics of vehicular networks, provide an overview of applications and associated requirements, along with challenges and their proposed solutions. In addition, we provide an overview of the current and past major ITS programs and projects in the USA, Japan and Europe. Moreover, vehicular networking architectures and protocol suites employed in such programs and projects in USA, Japan and Europe are discussed.

The security of vehicular ad hoc networks

Abstract: Vehicular networks are likely to become the most relevant form of mobile ad hoc networks. In this paper, we address the security of these networks. We provide a detailed threat analysis and devise an appropriate security architecture. We also describe some major design decisions still to be made, which in some cases have more than mere technical implications. We provide a set of security protocols, we show that they protect privacy and we analyze their robustness, and we carry out a quantitative assessment of the proposed solution.

VADD: Vehicle-Assisted Data Delivery in Vehicular Ad Hoc Networks

Abstract: Multihop data delivery through vehicular ad hoc networks is complicated by the fact that vehicular networks are highly mobile and frequently disconnected. To address this issue, we adopt the idea of carry and forward, where a moving vehicle carries a packet until a new vehicle moves into its vicinity and forwards the packet. Being different from existing carry and forward solutions, we make use of predictable vehicle mobility, which is limited by traffic pattern and road layout. Based on the existing traffic pattern, a vehicle can find the next road to forward the packet to reduce the delay. We propose several vehicle-assisted data delivery (VADD) protocols to forward the packet to the best road with the lowest data-delivery delay. Experimental results show that the proposed VADD protocols outperform existing solutions in terms of packet-delivery ratio, data packet delay, and protocol overhead. Among the proposed VADD protocols, the hybrid probe (H-VADD) protocol has a much better performance.