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Abstract
Routing is one of the challenging tasks in Delay Tolerant Networks (DTNs), due to the lack of global knowledge and sporadic contacts between nodes. Most existing studies take a greedy scheme in data forwarding process, i.e., only nodes with higher utility values than current carriers can be selected as relays. They lack an in-depth investigation on the main features of the optimal paths in Epidemic. These features are vital to any forwarding scheme that tends to make a trade-off between packet ...
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Abstract
In this paper, we replace the periodic transmission of control information by transmissions that depend on local network conditions. As a case study, we consider the proactive link state routing protocol OLSR running in a wireless network without infrastructure. Each node maintains a time series on its betweenness, a metric widely used in social network analysis. We interpret an anomaly in a node’s time series as a change in its role and use it to trigger the transmission of link state. ...
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Abstract
This paper discusses and validates energy-aware routing metrics which can be applied to any available routing protocol. We validate the metrics performance based on the two main branches of multihop routing, namely, link-state and distance-vector approaches. The validation is performed based upon discrete event simulations. ...
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In Personal Indoor and Mobile Radio Communications (PIMRC), 2012 IEEE 23rd International Symposium on (2012), pp. 1521-1527, doi:10.1109/pimrc.2012.6362589
Abstract
Mobility is a challenging issues in mobile networks which significantly impacts the performance of a variety of network protocols. Understanding user motion behavior can improve the performance of mobile network protocols in different aspects. Therefore, we consider how to analyze the motion behavior of mobile nodes in various environments. In this paper we propose a few mobility metrics useful for analysis of individual, collective and geographical behavior of mobile nodes and a simple supervised mobility pattern recognition method which is able ...
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In Proceedings of the 15th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems (2012), pp. 69-78, doi:10.1145/2387238.2387253
Abstract
In opportunistic environments, tasks such as content sharing and service execution among remote devices are facilitated by relays (devices with short-range wireless connectivity) that receive data, move around, and then forward the data. To achieve high throughput, it is important to secure forwarding and provide incentives for participation by relays. However, it is extremely challenging to monitor the behavior of relays in an opportunistic network due to sparse connectivity. Existing schemes do not work when selfish/malicious relays collude with each other ...
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In Proceedings of the 15th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems (2012), pp. 367-376, doi:10.1145/2387238.2387300
Abstract
In this paper, we introduce a user mobility modeling framework that accounts for both the users' social structure as well as the geographic diversity of the region of interest. SAGA, or Socially- and Geography-Aware mobility model, captures social features through the use of communities which cluster users with similar features such as average time in a cell, average speed, and pause time. SAGA accounts for geographic diversity by considering that different communities exhibit different interests for different locales; therefore, different communities ...
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In IEEE Conference on Local Computer Networks (LCN) (October 2012)
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Abstract
Social mobility models attempt to mimic human movement characteristics with the motivation to provide more realistic experimentation environments. Being recent, these models have a few gaps, being one of them the lack of a realistic function to dynamically track pauses. This paper proposes and evaluates such a function against real-traces. ...
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In 2012 IEEE/ACIS 11th International Conference on Computer and Information Science (May 2012), pp. 83-87, doi:10.1109/icis.2012.66
Abstract
Mobility models play a crucial role in mobility wireless networks with respect to evaluating the network protocols and performances. However, the majority of existing mobility models either does not exhibit realistic movement characteristics or modeling methods are too complex. In this paper, a new mobility model based on Location Attraction (LAMM) is proposed, which utilizes human's clustering features in real life. Through analyzing real GPS trace of mobile users, we observe the number and location attraction of hot regions. We find ...
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Abstract
We consider a novel application in wireless sensor networks where mobile phones and wireless sensors can collaborate to collect sensing data. Although mobile phones can perform sensing at different locations, it is a challenge to provide stable sensing quality and availability over the entire area. One approach is to deploy stationary sensors at specific locations to maintain the sensing quality and availability. In this paper, we present a mathematical programming model to minimise the deployment cost by placing a minimum number ...
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Abstract
In this paper we study multi-copy routing schemes in opportunistic networks. Compared to single-copy protocols, the multi-copy schemes expedite the mean delivery delay while consuming more resources and exposing lower packet delivery ratio in resource-constrained system. To enhance the system capacity, most recent works explore the impact of social structure on network performance. Their results indicate that integrating the social relationship into opportunistic routing can greatly improve the performance metrics especially in term of packet delivery ratio. Considering this fact, we ...
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In Proceedings of WCNC'12, the 10th IEEE Wireless Communications and Networking Conference (April 2012)
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In 2011 Seventh International Conference on Mobile Ad-hoc and Sensor Networks (December 2011), pp. 282-288, doi:10.1109/msn.2011.51
Abstract
Routing is one of the challenging tasks in Delay Tolerant Networks (DTNs), due to the lack of global knowledge and sporadic contacts between nodes. Most existing works take greedy mechanism to forward messages, i.e., only nodes which have higher quality metrics than current carriers can be selected as relays to final destinations. In this work, we explore the influence of strangers on routing performance under a more challenging scenario of pure darkness. We first present a method to identify the relationship ...
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In Proceedings of the Sixth Workshop on Hot Topics in Networks (HotNets-VI) (November 2007)
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Abstract
We report that human walk patterns contain statistically similar features observed in Levy walks. These features include heavy-tail flight and pause-time distributions and the super-diffusive nature of mobility. Human walks are not random walks, but it is surprising that the patterns of human walks and Levy walks contain some statistical similarity. Our study is based on 226 daily GPS traces collected from 101 volunteers in five different outdoor sites. The heavy-tail flight distribution of human mobility induces the super-diffusivity of travel, ...
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Abstract
Many empirical studies of human walks have reported that there exist fundamental statistical features commonly appearing in mobility traces taken in various mobility settings. These include: 1) heavy-tail flight and pause-time distributions; 2) heterogeneously bounded mobility areas of individuals; and 3) truncated power-law intercontact times. This paper reports two additional such features: a) The destinations of people (or we say waypoints) are dispersed in a self-similar manner; and b) people are more likely to choose a destination closer to its current ...
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Abstract
We report that human walks performed in outdoor settings of tens of kilometers resemble a truncated form of Levy walks commonly observed in animals such as monkeys, birds and jackals. Our study is based on about one thousand hours of GPS traces involving 44 volunteers in various outdoor settings including two different college campuses, a metropolitan area, a theme park and a state fair. This paper shows that many statistical features of human walks follow truncated power-law, showing evidence of scale-freedom ...
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In 2012 9th Annual Conference on Wireless On-Demand Network Systems and Services (WONS) (January 2012), pp. 143-150, doi:10.1109/wons.2012.6152221
Abstract
The paper proposes a new mobility model able to properly reproduce the spatial, temporal and social features that can be observed in real mobility datasets. The model, named Geo-CoMM, is based on the quantities that guide human mobility and their probability distributions by directly extracting their setting from the statistical analysis of GPS-based traces. In Geo-CoMM, people move within a set of geo-communities, i.e. locations loosely shared among people, following speed, pause time and choice rules whose distribution is obtained by ...
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Abstract
We present an efficient message delivery framework, called MeDeHa, which enables communication in an internet connecting heterogeneous networks that is prone to disruptions in connectivity. MeDeHa is complementary to the IRTF's Bundle Architecture: besides its ability to store messages for unavailable destinations, MeDeHa can bridge the connectivity gap between infrastructure-based and multi-hop infrastructure-less networks. It benefits from network heterogeneity (e.g., nodes supporting more than one network and nodes having diverse resources) to improve message delivery. For example, in IEEE 802.11 networks, ...
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Abstract
Wireless networks growing popularity coupled with a wide availability of wireless-enabled personal devices is today the basis for user-centric Internet architectures to evolve. Central to this new paradigm of user-centricity is the fact that today the Internet end-user exhibits a highly nomadic behavior, where most of the portable devices are carried by humans. The thesis proposed relates to the recent trend of social mobility modeling as a way to improve mobile network operation. The work is focused on the analysis of ...
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In Proceedings of the 14th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems (October 2011), pp. 159-168, doi:10.1145/2068897.2068927
Abstract
Pervasive networks formed by users' mobile devices have the potential to exploit a rich set of distributed service components that can be composed to provide each user with a multitude of application level services. However, mobile and pervasive networks suffer from intermittent connectivity, disconnections and partitions, such that opportunistic networking techniques are required to enable communication. This poses novel challenges to service composition techniques. While several works have discussed middleware and architecture for service composition in well-connected wired networks and in ...
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In 2010 8th IEEE International Conference on Pervasive Computing and Communications Workshops (PERCOM Workshops) (March 2010), pp. 760-763, doi:10.1109/percomw.2010.5470535
Abstract
This paper discusses the efficient message deletion mechanism, which will be able to apply regardless of applied routing protocol, in DTNs (Delay Tolerant Networks). In order to achieve an acceptable quality of message delivery probability, we will need to allow the multiple message replicas in the system. In this context, the capability and capacity of store-carry-and-forward at the nodes is crucial. Since the mobile nodes' storage capacity is not infinite, but is rather limited, an efficient resource management mechanism, i.e., message ...
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In 2011 International Conference on Distributed Computing in Sensor Systems and Workshops (DCOSS) (June 2011), pp. 1-8, doi:10.1109/dcoss.2011.5982168
Abstract
The need to monitor groups of mobile entities arises in many application contexts. Examples include the study of the social behavior of humans and wildlife, the shepherding of livestock, the care giving to people that are not self-sufficient. Human- or animal-borne wireless devices can be used to detect the joining or leaving of group members, even in infrastructure-less scenarios. In this work, we apply wireless sensor networks devices to this problem that has hitherto received little attention. We analyze three points ...
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Abstract
There is no doubt that networks are becoming increasingly heterogeneous and future internetworks will likely interconnect different types of networks including wired, infrastructure-based wireless as well as infrastructure-less wireless networks, a.k.a., multi-hop mobile ad-hoc networks (or MANETs). Integrating MANETs to infrastructure-based networks (wired or wireless) allows network coverage to be extended to regions where infrastructure deployment is sparse or nonexistent as well as a way to cope with intermittent connectivity. However, to date there are no comprehensive solutions that integrate MANETs ...
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Abstract
Simulating human mobility is important in mobile networks because many mobile devices are either attached to or controlled by humans and it is very hard to deploy real mobile networks whose size is controllably scalable for performance evaluation. Lately various measurement studies of human walk traces have discovered several significant statistical patterns of human mobility. Namely these include truncated power-law distributions of flights, pause-times and inter-contact times, fractal way-points, and heterogeneously defined areas of individual mobility. Unfortunately, none of existing mobility ...
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In 2010 International Conference on Cyber-Enabled Distributed Computing and Knowledge Discovery (October 2010), pp. 79-86, doi:10.1109/cyberc.2010.24
Abstract
Pervasive information gathering has became more and more important in people's daily life during the last decade. However, in some critical network scenarios such as Delay-Tolerant Mobile Sensor Network (DT-MSN), due to the sparse connectivity, node mobility and limited buffer, the traditional approaches for collecting information application may not work effectively without a stable end-to-end path from sensor nodes to the sink. In this paper, we propose a new carrier-based routing scheme based on nodal mobility pattern, named SAR-DM (Self-Adaptive Routing ...
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In 2011 IEEE 25th International Conference on Advanced Information Networking and Applications (AINA) (March 2011), pp. 69-76, doi:10.1109/aina.2011.83
Abstract
Frequent partitions, intermittent connectivity and message delivery delay are the commonly observed characteristics of disruption tolerant networks (DTNs). These networks often operate over extended periods since they are regularly deployed in harsh and constrained environments. Efficient energy conservation is therefore necessary to prolong network lifetime. Most DTNs nodes depend on mobility to deliver messages to their destination. The introduction of energy conservation, using a high power radio for data delivery and low power radio for neighbor discover to achieve higher energy ...
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Mobile Ad-Hoc and Sensor Systems, IEEE International Conference on In 2011 IEEE Eighth International Conference on Mobile Ad-Hoc and Sensor Systems, Vol. 0 (October 2011), pp. 322-331, doi:10.1109/mass.2011.39
Abstract
In this paper we show that human mobility exhibits "persistent" behavior in terms of the spatial density distribution of the mobile nodes over time. Using real mobility traces, we observe that the original non-homogeneous node spatial density distribution, where some regions may be quite dense while others may be completely deserted, is maintained at different instants of time. We also show that mobility models that select the next node position based on the position of other nodes, a la "preferential attachment", ...
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Abstract
Mobility is the most important factor in mobile adhoc networks (MANETs) and delay-tolerant networks (DTNs). Mobility models that fail to capture real movement pattern of mobile nodes will result in misleading guidelines on the design of new protocols and their performance evaluations and thus prevent us from making judicious decisions. ...
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Abstract
In this paper we discuss the independent message deletion mechanism for Delay Tolerant Networks (DTNs) multi-copy routing schemes, and the enhancement of this method with the knowledge of human mobility patterns. This mechanism can optimize the resource utilization and improve message delivery performance. In DTNs, communication is achieved by the movement of mobile devices and the ability to store-carry-and-forward the messages. Since contacts in this network occur opportunistically, multi-copy routing scheme suggests messages to be replicated, carried and forwarded by several ...
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Abstract
In recent years, individual based epidemic simulations on synthetic social contact networks have been proved useful in supporting public health epidemiology. In use of such models, it is often desirable to understand how disease spreads through a small subset of the population; furthermore often data is available that allows us to develop more refined representations of social contact networks that span these sub-populations. Examples include: schools, office campuses, military bases, etc. ...
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