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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

Scalability is an important consideration in the design any large network. In ad hoc networks, scalability is particularly critical as node mobility imposes additional challenges to growth. For example, frequent updates required by mobility make the conventional proactive routing protocols unable to work in large mobile ad hoc networks. Traditionally, node mobility in a wireless ad hoc network is viewed as the superposition of individual, dependent random moves of each node. In reality, mobile users tend to exhibit some kinds of collective group mobility patterns especially when the network size grows large. In fact, group mobility has been exploited to improve the scalability of network protocols such as routing. For example, LANMAR routing uses mobile groups the basis of hierarchical network architecture. However, the original LANMAR routing assumes that ALL nodes move in groups (e.g. homogeneous group mobility), which is quite unrealistic. In general, moving teams do coexist with individual roaming nodes creating what may be called heterogeneous group mobility scenarios, this paper, we propose a hybrid landmark routing (hybrid LANMAR) scheme which takes advantages of group mobility to improve network scalability, while at the same time supporting individual mobility efficiently. Mobile groups are explored following way similar to LANMAR routing and individually moving nodes e handled in an on-demand fashion. In this way, we gracefully integrate advantages of both proactive and on-demand routing. Simulation results show that hybrid LANMAR can greatly improve network scalability in heterogeneous motion scenarios.

Hybrid landmark routing in ad hoc networks with heterogeneous group mobility

Due to the self organizing characteristic of Ad Hoc network, it is difficult to adopt traditional delay measurement techniques in a multi hop Wireless Mesh network (WMN). This problem is much more complicated in multi-radio environment because of the mutual interferences that contribute significantly to the overall delay. We present an experimental methodology to obtain an estimate of average intra-node delay and inter-node delay for packets of variable payload size in both single radio and multi-radio environment without the constraint of clock synchronization between the nodes. Our results provide insights on comparing performances between single and multi-radio environment with some interesting findings like periodic nature for intra-node delay with oscillating frequency distribution. Finally our statistical analysis validates the linear relationship between end to end delay, intra-node delay and inter-node delay.

Delay analysis of Wireless Ad Hoc networks: Single vs. multiple radio

Techniques derived from biological systems explore a new dimension of research in Cognitive Radio Networks (CRNs). In this paper, we address the stability issue of CRN routing, being motivated by the adaptive ‘Attractor-Selector’ model. Our work includes designing a routing protocolnamed Bio-inspired Stable Routing (BioStaR) that increases route stability by maximizing the Spectrum Opportunity (SOP)and also minimizes the channel switching delay and signaling overhead. To the best of our knowledge, this is by far the first bio-inspired CRN routing that takes into account the above mentioned factors. Our simulation results show that this protocol accounts for both higher stability of route and less signaling overhead in spectrum-agile CRN environments.

/pdf/biostar-a-bio-inspired-stable-routing-for-cognitive-radio-1mueineu60.pdf

BioStaR: A Bio-inspired Stable Routing for Cognitive Radio Networks

Routing protocols for mobile ad-hoc networks have been evaluated extensively through simulation because various network conditions can be easily configured, tested, and replicated across different schemes in simulation than in a real system. Recently, some of these schemes have been implemented in academic, industry and defense testbeds. This gives researchers an opportunity to validate their simulation results with actual implementations. In this paper we report the lessons learned from the implementation of LANMAR (Pei et al. (2000)), a scalable routing protocol that was developed at UCLA as part of large-scale ad hoc network architecture for autonomous unattended agents under ONR support. LANMAR is designed to provide efficient, scalable routing in large ad-hoc wireless networks that exhibit group mobility. In this paper we describe the implementation of this protocol in Linux environments and report on experimental results based on this implementation. The results and lessons from these experiments have enriched our understanding of the LANMAR protocol and its interaction with the other layers and the environment, paving the way to protocol refinements and more efficient implementations.

/pdf/experimental-evaluation-of-lanmar-a-scalable-ad-hoc-routing-1d9zecv7md.pdf

Experimental evaluation of LANMAR, a scalable ad-hoc routing protocol

This study explores an innovative framework for distributed traffic monitoring and information aggregation using vehicle-to-vehicle (V2V) communications alone. We envision the proposed framework as the foundation to an alternative or supplemental traffic operation and management system, which could be particularly helpful under abnormal traffic conditions caused by unforeseen disasters and special events. Each equipped vehicle, through the distributed protocols developed, keeps track of the average traffic density and speed within a certain range, flags itself as micro-discontinuity in traffic if appropriate, and cross-checks its flag status with its immediate up- and down-stream vehicles. The micro-discontinuity flags define vehicle groups with similar traffic states, for initiating and terminating traffic information aggregation. The framework is validated using a microscopic traffic simulation platform VISSIM and its built-in component object model. Vehicle groups are successfully identified and their average speed and density effectively estimated. The impact of market penetration rate (MPR) is also investigated with a new methodology for performance evaluation under multiple traffic scenarios. Our simulation results show that the proposed framework lends itself better to more congested traffic conditions for any given MPR. With 50% MPR, the framework is able to provide information coverage for at least 37.76% of the simulated roadway facility under various traffic scenarios. This indicates that proposed framework could be useful with an MPR as low as 50%. Even with an MRP of 20%, the coverage ratio, under relatively congested traffic, can still reach around 58.82%. The framework is able to provide accurate speed estimation at high spatial resolution for the simulated roadway facility. The maximum relative error is under 10% for relatively congested traffic even with MPR as low as 20%. When there is a wider range of speed distribution (less congested traffic), the worst-case maximum relative error is still under 15% when MPR =  20 % . The density estimation is more sensitive to MPR, and is more accurate under low demand and high MPR scenarios. As expected, the accuracy of both speed and density estimation increases with MPR for any given traffic scenario.

Xiaoyan Hong

Papers

Hybrid landmark routing in ad hoc networks with heterogeneous group mobility

Delay analysis of Wireless Ad Hoc networks: Single vs. multiple radio

BioStaR: A Bio-inspired Stable Routing for Cognitive Radio Networks

Experimental evaluation of LANMAR, a scalable ad-hoc routing protocol

A distributed framework for network-wide traffic monitoring and platoon information aggregation using V2V communications