Journal of Sensor and Actuator Networks

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Open AccessArticle

Towards Long-Term Multi-Hop WSN Deployments for Environmental Monitoring: An Experimental Network Evaluation

by Miguel Navarro, Tyler W. Davis, German Villalba, Yimei Li, Xiaoyang Zhong, Newlyn Erratt, Xu Liang and Yao Liang

J. Sens. Actuator Netw. 2014, 3(4), 297-330; https://doi.org/10.3390/jsan3040297 - 5 Dec 2014

Cited by 22 | Viewed by 8474

Abstract

This paper explores the network performance and costs associated with the deployment, labor, and maintenance of a long-term outdoor multi-hop wireless sensor network (WSN) located at the Audubon Society of Western Pennsylvania (ASWP), which has been in operation for more than four years for environmental data collection. The WSN performance is studied over selected time periods during the network deployment time, based on two different TinyOS-based WSN routing protocols: commercial XMesh and the open-source Collection Tree Protocol (CTP). Empirical results show that the network performance is improved with CTP (i.e., 79% packet reception rate, 96% packet success rate and 0.2% duplicate packets), versus using XMesh (i.e., 36% packet reception rate and 46% packet success rate, with 3%–4% duplicate packets). The deployment cost of the 52-node, 253-sensor WSN is $31,500 with an additional $600 per month in labor and maintenance resulting in a cost of $184 m⁻²·y⁻¹ of sensed area. Network maintenance during the first four years of operation was performed on average every 12 days, costing approximately $187 for each field visit. Full article

(This article belongs to the Special Issue Environmental Wireless Sensor Networks)

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251 KiB

Open AccessArticle

Towards a Fair and Efficient Packet Scheduling Scheme in Inter-Flow Network Coding

by Jin Wang, Teck Yoong Chai and Wai-Choong Wong

J. Sens. Actuator Netw. 2014, 3(4), 274-296; https://doi.org/10.3390/jsan3040274 - 4 Nov 2014

Cited by 2 | Viewed by 6531

Abstract

Network coding techniques are usually applied upon network-layer protocols to improve throughput in wireless networks. In scenarios with multiple unicast sessions, fairness is also an important factor. Therefore, a network coding-aware packet-scheduling algorithm is required. A packet-scheduling algorithm determines which packet to send next from a node’s packet backlog. Existing protocols mostly employ a basic round-robin scheduling algorithm to give “equal” opportunities to different packet flows. In fact, this “equal”-opportunity scheduling is neither fair, nor efficient. This paper intends to accentuate the importance of a coding-aware scheduling scheme. With a good scheduling scheme, we can gain more control over the per-flow throughput and fairness. Specifically, we first formulate a static scheduling problem and propose an algorithm to find the optimal scheduling scheme. We then extend the technique to a dynamic setting and, later, to practical routing protocols. Results show that the algorithm is comparatively scalable, and it can improve the throughput gain when the network is not severely saturated. The fairness among flows is drastically improved as a result of this scheduling scheme. Full article

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33151 KiB

Open AccessArticle

Towards Sensor-Actuator Coupling in an Automated Order Picking System by Detecting Sealed Seams on Pouch Packed Goods

by Frank Weichert, Adrian Böckenkamp, Christian Prasse, Constantin Timm, Bartholomäus Rudak, Klaas Hölscher and Michael Ten Hompel

J. Sens. Actuator Netw. 2014, 3(4), 245-273; https://doi.org/10.3390/jsan3040245 - 14 Oct 2014

Cited by 3 | Viewed by 9828

Abstract

In this paper, a novel concept of coupling the actuators of an automated order picking system for pouch packed goods with an embedded CCD camera sensor by means of image processing and machine learning is presented. The picking system mechanically combines the conveyance and singularization of a still-connected chain of pouch packed goods in a single machinery. The proposed algorithms perform a per-frame processing of the captured images in real-time to detect the sealed seams of the ongoing pouches. The detections are used to deduce cutting decisions in order to control the system’s actuators, namely the drive pulley for conveyance and the cutting device for the separation. Within this context, two controlling strategies are presented as well which specify the interaction of the sensor and the actuators. The detection is carried out by two different marker detection strategies: enhanced Template Matching as a heuristic and Support Vector Machines as a supervised classification based concept. Depending on the employed marker, detection rates of almost 100% with a calculation time of less than 40 ms are possible. From a logistic point of view, sealed seam widths of 20 mm prove feasible. Full article

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J. Sens. Actuator Netw., Volume 3, Issue 4 (December 2014) – 3 articles , Pages 245-330

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