Hoang Anh Nguyen

Context information prediction for social-based routing in opportunistic networks

Context information can be used to streamline routing decisions in opportunistic networks. We propose a novel social context-based routing scheme that considers both the spatial and the temporal dimensions of the activity of mobile nodes to predict the mobility patterns of nodes based on the BackPropagation Neural Networks model.

Probabilistic Routing Protocol for Intermittently Connected Mobile Ad hoc Network (PROPICMAN)

Routing in intermittently connected mobile ad hoc networks (ICMAN) is a very challenging problem because disconnections are prevalent and the lack of knowledge about network dynamics hinders good decision making. In ICMAN one of the most important decisions is how to choose the most suitable intermediate(s) to forward the message to the destination. We propose in this document a new algorithm (PROPICMAN) that, based on context information, allows the sender to select the neighbor(s) such that the message has the highest probability to reach the destination.

Sensor node lifetime: An experimental study

Node lifetime is a key performance metric in wireless sensor network (WSN) research. Simplistic assumptions and naïve lifetime estimation techniques invariably prove to be extremely unreliable in practice, to the point that premature battery depletion notoriously affects real-world deployments. In this paper we adopt an experimental approach and employ various types of real-world batteries to determine the actual lifespan of a sensor node under common operating conditions. We present a rich set of results from an extensive experimental campaign based on the widely used TelosB platform running TinyOS. We have measured the actual node lifetime using various brands of commercial batteries as a function of different combinations of application parameters. Some of our observations match previously published results that are often neglected, while others underscore less known properties of low-power radios.

Routing issues in opportunistic networks

The opportunistic networking idea stems from the critical review of the research field on Mobile Ad hoc Networks (MANET). After more than ten years of research in the MANET field, this promising technology still has not massively entered the mass market. One of the main reasons of this is nowadays seen in the lack of a practical approach to the design of infrastructure-less multi-hop ad hoc networks [186, 185]. One of the main approaches of conventional MANET research is to design protocols that mask the features of mobile networks via the routing (and transport) layer, so as to expose to higher layers an Internet-like network abstraction. Wireless networks’ peculiarities, such as mobility of users, disconnection of nodes, network partitions, links’ instability, are seen—as in the legacy Internet—as exceptions. This often results in the design of MANET network stacks that are significantly complex and unstable [107].

Routing in Opportunistic Networks

In Opportunistic Networks (OppNets), mobile devices transmit messages by exploiting the direct contacts, without the need of an end-to-end infrastructure. Disconnections of nodes and high churn rates are normal features of opportunistic networks. Hence, routing is one of the main challenges in this environment. In this article, we provide a survey of the main routing approaches in OppNets and classify them into three classes: context-oblivious, mobility-based, and social context-aware routing. We emphasize the role of context information in forwarding data in OppNets, and evaluate the relative performance of the three routing techniques. Finally, we present how context-based information is used to route data in a specific subclass of OppNets: Sensor Actor Networks (SANETs).

On context awareness and social distance in human mobility traces

Opportunistic networks consist of mobile devices, carried by people in their everyday lives. They organize autonomously to exchange data with direct neighbors without the use of any infrastructural services. Since the devices are carried by humans, one of the main challenges to consider in opportunistic networks is the human mobility behavior. However, little work exists on how the social behavior of people drives their mobility behavior and how this context information can be systematically leveraged for opportunistic networking applications. This paper tackles this problem by providing both experimental and theoretical analysis of human mobility context information. We present a novel real world experiment with sensor nodes carried by people to demonstrate and study the effect of context on people mobility. Furthermore, we define a novel metric of social distance to put this new evidence on solid mathematical foundation. Thus, our work puts a basis to systematically leveraging context information for opportunistic networking applications and services. Additionally, our experimental data traces enable testing and evaluation of such novel services in a real world scenario.

Spatiotemporal routing algorithm in opportunistic networks

We propose a new routing scheme (SpatioTempo) based on modeling the mobility of device carriers in periods and cycles. SpatioTempo exploits both the spatial (context) and the temporal (periodical behavior) characteristics of people to better route and optimize the message retransmissions. The combination with Propicman[1] imparts the strong points of the latter, such as context based routing and routing with zero knowledge.

Demonstrating seamless handover of multi-hop networks

Traditionally, global network mobility problem is addressed at networking layer. However, none of these solution is designed for supporting seamless horizontal and vertical handover. The demonstrated solution, called WiOptiMo, provides always-on, continuous and optimized network services, whenever possible, to the applications independently from lower layers. The whole network can move and all network nodes can continue to work with the optimal connection, until some possible connection exists. This paper shows how the network mobility can be handled at application layer with WiOptiMo and presents a demonstration scenario with a mobile network, whose nodes access audio and video application without being affected by the fact that the network moves and switches from one network access to another.

PROSAN: probabilistic opportunistic routing in SANETs

SANET react to a sensed event by means of actuators. The sensor nodes thus need to communicate with actuators, and this can involve several hops if the network is large. To reduce unbalanced traffic distribution and costs, sensor networks can be modeled as intermittently connected mobile networks where special nodes are used for forwarding. However, this routing approach could be not appropriate for SANET as can introduce delays. We propose, to overcome this problem, PROSAN algorithm that exploit context based opportunistic routing for mobile SANET, by adapting the Propicman algorithm to this more constrained scenario. This has several advantages: i) based on context information, PROSAN allows the sender to select the next hop such that the message has the highest probability to reach the destination; ii) due to sensor nodes mobility, there is no need for special mobile nodes and the mobility of all nodes contributes to meet the time constraints; iii) due to neighbor(s) selection, the energy and memory consumption are reduced. We also combine it with mobility-assisted forwarding into a hybrid scheme, for better reliability. The initial simulation results show that the use of probabilistic opportunistic routing can be very beneficial and opens to a new interesting direction within SANET.