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Statistics for Spatial Data.

"A Survey of Mobility Models for Ad Hoc Network Research," Wireless Comm. & Mobile Computing (WCMC) : Special issue on Mobile Ad Hoc Networking : Research

In the performance evaluation of a protocol for an ad hoc network, the protocol should be tested under realistic conditions including, but not limited to, a sensible transmission range, limited buffer space for the storage of messages, representative data traffic models, and realistic movements of the mobile users (i.e., a mobility model). This paper is a survey of mobility models that are used in the simulations of ad hoc networks. We describe several mobility models that represent mobile nodes whose movements are independent of each other (i.e., entity mobility models) and several mobility models that represent mobile nodes whose movements are dependent on each other (i.e., group mobility models). The goal of this paper is to present a number of mobility models in order to offer researchers more informed choices when they are deciding upon a mobility model to use in their performance evaluations. Lastly, we present simulation results that illustrate the importance of choosing a mobility model in the simulation of an ad hoc network protocol. Specifically, we illustrate how the performance results of an ad hoc network protocol drastically change as a result of changing the mobility model simulated.

/pdf/a-survey-of-mobility-models-for-ad-hoc-network-research-ygkxat400x.pdf

A survey of mobility models for ad hoc network research

http://www.csun.edu/~andrzej/COMP529-S05/papers/Mesh%20Networks%20Survey.pdf

Wireless mesh networks: a survey

Vehicular networks will become an important component for information accesses in one's daily life. A vehicular network provides a vehicular user not only chances to communicate with peer vehicles but also to use Internet through roadside access points (APs). During a trip a vehicular user could roam across multiple APs either belong to their home wireless domain or to domains owned by different authorities. This poses challenges on privacy and network performance to the current public wireless network access protocols. In this paper we explore an idea that shifts the paradigm of authentcation that goes back to home networks to a paradigm of authentication that performs at the APs. We propose three authentication schemes in realizing the idea. These schemes are designed for preserving user's identity and location privacy. They also greatly reduce response time for authentication when roaming. The paper then analyzes the security and privacy properties of these schemes as well as the efficiency of them.

/pdf/privacy-preserving-quick-authentication-in-fast-roaming-3tk5fqkbwy.pdf

Privacy-Preserving Quick Authentication in Fast Roaming Networks

Traditionally the anonymity of an entity of interest can be achieved by hiding it among a group of other entities with similar characteristics, i.e., an anonymity set. In mobile ad hoc networks, generating and maintaining such an anonymity set for any ad hoc node are challenging because of the node mobility and consequently of the dynamic network topology. In this paper, we address the problem of the destination anonymity. We propose protocols that use fuzzy destination position to generate a geographic area called anonymity zone (AZ). A packet for a destination is delivered to all the nodes in the AZ, which, consequently, make up the anonymity set. The size of the anonymity set may decrease because nodes are mobile, yet the corresponding management on anonymity set is simple. We design techniques to further improve node anonymity. We use extensive simulation to study the node anonymity and routing performance, and to determine the parameters that most impact the anonymity level that can be achieved by our protocol.

/pdf/achieving-anonymity-in-mobile-ad-hoc-networks-using-fuzzy-2qeqte0xu1.pdf

Achieving Anonymity in Mobile Ad Hoc Networks Using Fuzzy Position Information

Scientists take interest in monitoring underwater ecosystems over time because it provides rich data on ecology, pollution, and climate change. We thus envision a searchable monitoring system building on top of the Underwater Sensor Network (UWSN) deployed to collect and deliver data from underwater sensors to globally distributed scientists as they request. In this extended abstract, we explore Named-Data Networking (NDN) as an approach to support data retrieval from this underwater acoustic network. Also, we present a comparative simulation study to investigate several issues relating to the feasibility and performance. These issues are raised due to a couple of choices available as popular research results in terms of how the network can be established.

A Named-Data Networking Approach to Underwater Monitoring Systems

Named data networking (NDN) has been considered as a promising networking architecture for vehicular ad-hoc networks (VANETs). However, interest forwarding in NDN suffers severe issues in vehicular environment. Broadcast storms result in much packet loss and huge transmission overhead. Also, link disconnection caused by highly dynamic topology leads to low packet delivery ratio and extreme long delay in data retrieval. Thus, an efficient NDN forwarding strategy to retrieve data is urgently required. In this paper, we propose the density-aware delay-tolerant (DADT) interest forwarding strategy to retrieve traffic data in vehicular NDN. DADT specifically addresses data retrieval during network disruptions using delay tolerant networking (DTN). It makes retransmission decisions based on directional network density. Also, DADT mitigates broadcast storms by using a rebroadcast deferring timer. We compared DADT against other strategies through simulation and the results show that it can achieve a higher satisfaction ratio while maintaining low transmission overhead.

Delay-tolerant forwarding strategy for named data networking in vehicular environment

This presentation describes an innovative system for taxi hailing service using the Dedicated Short Range Communications (DSRC) infrastructure. Unlike existing automated taxi dispatching systems, this V2I based ITS application does not require any established operational center or explicit prior booking request through central operator of the taxi company. Rather, it provides distributed, self-organized and real time service of hailing a taxi cab in urban area. In this presentation, the authors briefly introduce the design of the system and the communication protocols, along with preliminary evaluation results that reveal numerous benefits of implementing this system. The proposed DSRC based taxi hailing system consists of a Roadside Hailing Device (RHD), Vehicle Response Device (VRD) and a signaling protocol that enables both direct communication and multi-hop half-duplex communication between the hailing and response units. The RHD can be designed by simply incorporating a calling interface with the existing state of the art Roadside Equipment (RSEs) being deployed by the government. The taxi hailing application can be installed in the RSEs whereas the calling interface would contain a push-button and a display unit. The push button will be used for making a request for taxi hailing. This would initiate the request to be broadcasted using the DSRC transceiver of the RSE within certain coverage area. The status of the request can be represented by a hailing cycle which can be displayed to the customer using the display unit. The application will handle the selection and dispatching procedure, whereas the communication protocol will control the multi-hop wireless communication using other RSEs when no taxi is available within the single hop coverage area of the RSE. On the other hand, any aftermarket DSRC On-Board Unit (OBU) can be installed with the taxi hailing application to serve the purpose of VRD. Upon receiving any hailing request, the graphical interface will show the pickup location on the map of the GPS which is also integrated with the OBU device. If a taxi driver responds to that request, the RHD will be notified through the communication protocol. The RHD can dispatch the closest taxi in case multiple taxis respond to a hailing request. The communication protocol confirms the dispatched taxi about the service, whereas other taxis receive denial notification. This application can be designed to incorporate V2V communication where the density of RSE is very sparse. This will increase the availability of taxis in rural or suburban areas. Preliminary simulation and analysis have been conducted to evaluate the benefit of this application using real world GPS traces from San Francisco Yellow cabs. Our results show that, typically in a downtown area a person can hail a taxi within less than 2 minutes where normal street hailing process would take more than 15 minutes in rush hours. Our results also show that the availability of the empty cabs can be increased up to 30 times more than that of street hailing considering only a broadcast range of 500 meters. The authors conclude that this system can make a revolutionary change in the day today urban life, particularly for the crowded metropolitan cities around the world where people spend several exhaustive hours in traveling to and from work places.

Xiaoyan Hong

Papers

Privacy-Preserving Quick Authentication in Fast Roaming Networks

Achieving Anonymity in Mobile Ad Hoc Networks Using Fuzzy Position Information

A Named-Data Networking Approach to Underwater Monitoring Systems

Delay-tolerant forwarding strategy for named data networking in vehicular environment

Innovative Taxi Hailing System using DSRC Infrastructure