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- Wennerström, Hjalmar, 1984-, et al.
(författare)
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A Game Theoretic Approach to Sensor Data Communications in an Opportunistic Network
- 2015
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Ingår i: Proc. International Conference on Communications. - Piscataway, NJ : IEEE. - 9781467364324 ; , s. 6306-6311
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Konferensbidrag (refereegranskat)abstract
- Opportunistic communication coupled with a sensing task enables the collection and spreading of sensory information in areas without global connectivity, providing useful information in challenging environments. In this paper, we consider an opportunistic sensor network where the mobility of users enables both the measurement and spreading of sensor data. We motivate user participation through a game theoretic approach, which is designed to ensure a fair and efficient exchange of sensor messages.The message exchange is modeled as a two-player game where sensor measurements are exchanged between nodes in a contrite tit-for-tat manner. The proposed game captures the nodes desire to limit energy consumption while at the same time obtaining messages containing useful information.We show that the best response in the game is a Pareto optimal subgame perfect equilibrium. The game is evaluated through simulation in a realistic scenario and compared with three other approaches, generating the best overall efficiency by striking a balance between size and content of messages.
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| 2. |
- Wennerström, Hjalmar, 1984-, et al.
(författare)
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A Long-Term Study on the Effects of Meteorological Conditions on 802.15.4 Links
- 2012
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Ingår i: 8th Swedish National Computer Networking Workshop, Stockholm, June 7-8.
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Konferensbidrag (refereegranskat)abstract
- Remote monitoring of natural phenomena using wireless sensor networks requires these networks to successfully operate while being exposed to the surrounding environment. Weather conditions are an essential aspect of the environment, therefore it is important to understand the effects of weather on sensor networks. This understanding is especially important since weather varies strongly over time and affects the communication between sensor nodes. In our ongoing work we study how different meteorological conditions influence radio links in outdoor wireless sensor networks that use IEEE 802.15.4 for communication. We deploy an experimental setup next to a meteorological research station and aim to run experiments over several months in order to capture both short- and long-term changes in the link characteristics. We show some initial measurements of the deployment, highlighting influences on packet reception rate and signal strength.
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| 3. |
- Wennerström, Hjalmar, 1984-
(författare)
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A Node-Link Perspective on the Impact of Local Conditions in Sensor Networks
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sensor networks are made up of small battery-powered sensing devices with wireless communication capabilities, enabling the network to monitor the environment in which it is deployed. Through their flexible and cable-free design these networks open up for new deployment scenarios that were previously not plausible such as during a natural disaster. Motivated by scenarios where centralized oversight is not possible the focus of this thesis is to equip nodes with further adaptability to changes in the links it has with other nodes. This is achieved through contributions in three areas focusing on observations from a node-link perspective.First, the impact the local environment has on the nodes is explored by deploying a sensor network outdoors next to a meteorological station to correlate the variations in link quality to the changes in the environment. The work identifies temperature as the main factor, where through further investigations in a controlled setting, a linear relationship between the decrease in signal quality and the increase in temperature is described.Secondly, the thesis address how nodes in a sensor network can be motivated to exchange data by modeling it as a game. The game theoretic design is motivated by the absence of any centralized control and focus on the nodes as individual users in the network. The presented design motivates the selfish nodes to participate in the exchange of sensor data, showing that it is the best strategy.Lastly, by exploring and understanding how connections in a mobile sensor network occur, nodes are given more flexibility to determine how to send and sample sensor data. This adaptability to contact occurrences is shown to provide better ways of sending data by selecting higher quality links as well as making sampling more energy preserving by reducing the rate in the vicinity of other nodes.
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| 4. |
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| 5. |
- Wennerström, Hjalmar, 1984-, et al.
(författare)
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Considering Multi-Contact Encounters in Opportunistic Networks
- 2015
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Ingår i: Proceedings of the 10th ACM MobiCom Workshop on Challenged Networks. - New York, NY, USA : ACM Digital Library. - 9781450335430
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Konferensbidrag (refereegranskat)abstract
- Opportunistic networks, often characterized by their intermittent connectivity and sparsity of nodes, has sparked routing in these networks to focus on isolated contact opportunities. Routing has predominantly been viewed as an exchange of messages between a pair of nodes. In this paper, we take a new look at contact opportunities, specifically focusing on the occurrence of having multiple simultaneous node contacts. Multi-contact encounters warrants a more holistic view of routing decisions, where more factors than just the features of a message-node tuple can be considered. We discuss these aspects and propose a protocol addition to leverage multi-contact opportunities with the notion of heterogeneous link quality, in order to limit energy consumption. The approach, implemented for the Epidemic, Spray-and-Wait and PRoPHETv2 protocols, re-evaluates routing decisions, weighting the routing metrics value against the estimated cost of the relay. Results indicate a two to three fold decrease in the number of messages lost, as well as a reduction in message relays, while maintaining a high delivery ratio for all three protocols.
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