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Enhanced Power Saving Mode for Low-Latency Communication in Multi-Hop 802.11 Networks
Disney Research Zurich.
Disney Research Zurich.
Disney Research Zurich.
2014 (English)In: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 23, no December 2014, 18-33 p.Article in journal (Refereed) Published
Abstract [en]

The Future Internet of Things (IoT) will connect billions of battery-powered radio-enabled devices. Some of them may need to communicate with each other and with Internet gateways (border routers) over multi-hop links. While most IoT scenarios assume that for this purpose devices use energy-efficient IEEE 802.15.4 radios, there are use cases where IEEE 802.11 is preferred despite its potentially higher energy consumption. We extend the IEEE 802.11 power saving mode (PSM), which allows WLAN devices to enter a low-power doze state to save energy, with a traffic announcement scheme that facilitates multi-hop communication. The scheme propagates traffic announcements along multi-hop paths to ensure that all intermediate nodes remain awake to receive and forward the pending data frames with minimum latency. Our simulation results show that the proposed Multi-Hop PSM (MH-PSM) improves both end-to-end delay and doze time compared to the standard PSM; therefore, it may optimize WLAN to meet the networking requirements of IoT devices. MH-PSM is practical and software-implementable since it does not require changes to the parts of the IEEE 802.11 medium access control that are typically implemented on-chip. We implemented MH-PSM as a part of a WLAN driver for Contiki OS, which is an operating system for resource-constrained IoT devices, and we demonstrated its efficiency experimentally.

Place, publisher, year, edition, pages
2014. Vol. 23, no December 2014, 18-33 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-132366DOI: 10.1016/j.adhoc.2014.06.001ISI: 000342251600002Scopus ID: 2-s2.0-84906309571OAI: oai:DiVA.org:kth-132366DiVA: diva2:659582
Note

QC 20140826

Available from: 2013-10-25 Created: 2013-10-25 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Coexistence and Energy Efficiency in Wireless Networks
Open this publication in new window or tab >>Coexistence and Energy Efficiency in Wireless Networks
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dynamic spectrum access has been recently proposed to increase the utilization of the licensed spectrum bands, and support the constantly growing volumes of mobile traffic in the modern society. At the same time, the increasing demand for wireless connectivity, as a result of the rapid emergence of innovative wireless and mobile services, has led to the deployment of various wireless technologies in the open ISM bands. This thesis addresses the effective coexistence among the diverse wireless technologies in the above scenarios, and the energy efficiency of the deployed wireless systems, both listed among the key challenges that wireless networking is facing today.

We discuss cooperative sensing, a fundamental mechanism for allowing unlicensed users perform opportunistic access in the licensed spectrum. Considering the scenario where the users perform both sensing and unlicensed spectrum access, we evaluate the efficiency of multi-channel cooperative sensing schemes with respect to the per user achievable capacity. We conclude that a careful optimization of both the number of sensed channels, and the allocation of sensing duties to the network users is necessary to achieve high capacity gains in large-scale networks of unlicensed users.

We address a number of energy efficient design issues for sensor networks and wireless LANs. We study how to improve the energy efficiency of lowpower sensor networks operating under the interference from a coexisting WLAN. We propose a cognitive, cross-layer access control mechanism that minimizes the energy cost for multi-hop WSN communication, by deriving energy-optimal packet lengths and single-hop transmission distances, based on the knowledge of the stochastic channel activity patterns of the interfering WLAN. We show that the proposed mechanism leads to significant performance improvements on both energy efficiency, as well as end-to-end latency in multi-hop WSN communication, under different levels of interference. Additionally, we develop and validate the considered WLAN channel activity model and implement efficient, lightweight, real-time parameter estimation methods.

We investigate how to enhance the multi-hop communication performance in ad hoc WLANs, when 802.11 stations operate under a power saving dutycycle scheme. We extend the traffic announcement scheme of the 802.11 power saving mode, allowing the stations to propagate pending frame notifications to all nodes in the end-to-end forwarding path of a network flow. We study the performance of the proposed scheme with respect to end-to-end packet delay and signaling overhead, while we investigate the impact on the achievable duty-cycle ratios of the wireless stations. For the purpose of the evaluation, and for the comparison with the standard 802.11 power saving mechanism, we implement the protocol extension in a development platform.

Finally, we study how the combination of the objectives for energy efficiency and a high quality of service impacts the topology stability of selforganized ad hoc networks comprised of individual agents. Based on a noncooperative game theoretic model for topology formation, we identify key extensions in the nodes’ strategy profile space that guarantees a stable network formation under multi-objective player utility functions.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. vii, 64 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2015:009
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-165168 (URN)978-91-7595-520-9 (ISBN)
Public defence
2015-05-12, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:15 (English)
Opponent
Supervisors
Note

QC 20150424

Available from: 2015-04-24 Created: 2015-04-23 Last updated: 2015-04-24Bibliographically approved

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