4,623 research outputs found
GCP: Gossip-based Code Propagation for Large-scale Mobile Wireless Sensor Networks
Wireless sensor networks (WSN) have recently received an increasing interest.
They are now expected to be deployed for long periods of time, thus requiring
software updates. Updating the software code automatically on a huge number of
sensors is a tremendous task, as ''by hand'' updates can obviously not be
considered, especially when all participating sensors are embedded on mobile
entities. In this paper, we investigate an approach to automatically update
software in mobile sensor-based application when no localization mechanism is
available. We leverage the peer-to-peer cooperation paradigm to achieve a good
trade-off between reliability and scalability of code propagation. More
specifically, we present the design and evaluation of GCP ({\emph Gossip-based
Code Propagation}), a distributed software update algorithm for mobile wireless
sensor networks. GCP relies on two different mechanisms (piggy-backing and
forwarding control) to improve significantly the load balance without
sacrificing on the propagation speed. We compare GCP against traditional
dissemination approaches. Simulation results based on both synthetic and
realistic workloads show that GCP achieves a good convergence speed while
balancing the load evenly between sensors
Wisent: Robust Downstream Communication and Storage for Computational RFIDs
Computational RFID (CRFID) devices are emerging platforms that can enable
perennial computation and sensing by eliminating the need for batteries.
Although much research has been devoted to improving upstream (CRFID to RFID
reader) communication rates, the opposite direction has so far been neglected,
presumably due to the difficulty of guaranteeing fast and error-free transfer
amidst frequent power interruptions of CRFID. With growing interest in the
market where CRFIDs are forever-embedded in many structures, it is necessary
for this void to be filled. Therefore, we propose Wisent-a robust downstream
communication protocol for CRFIDs that operates on top of the legacy UHF RFID
communication protocol: EPC C1G2. The novelty of Wisent is its ability to
adaptively change the frame length sent by the reader, based on the length
throttling mechanism, to minimize the transfer times at varying channel
conditions. We present an implementation of Wisent for the WISP 5 and an
off-the-shelf RFID reader. Our experiments show that Wisent allows transfer up
to 16 times faster than a baseline, non-adaptive shortest frame case, i.e.
single word length, at sub-meter distance. As a case study, we show how Wisent
enables wireless CRFID reprogramming, demonstrating the world's first
wirelessly reprogrammable (software defined) CRFID.Comment: Accepted for Publication to IEEE INFOCOM 201
Efficient and Reliable Task Scheduling, Network Reprogramming, and Data Storage for Wireless Sensor Networks
Wireless sensor networks (WSNs) typically consist of a large number of resource-constrained nodes. The limited computational resources afforded by these nodes present unique development challenges. In this dissertation, we consider three such challenges. The first challenge focuses on minimizing energy usage in WSNs through intelligent duty cycling. Limited energy resources dictate the design of many embedded applications, causing such systems to be composed of small, modular tasks, scheduled periodically. In this model, each embedded device wakes, executes a task-set, and returns to sleep. These systems spend most of their time in a state of deep sleep to minimize power consumption. We refer to these systems as almost-always-sleeping (AAS) systems. We describe a series of task schedulers for AAS systems designed to maximize sleep time. We consider four scheduler designs, model their performance, and present detailed performance analysis results under varying load conditions. The second challenge focuses on a fast and reliable network reprogramming solution for WSNs based on incremental code updates. We first present VSPIN, a framework for developing incremental code update mechanisms to support efficient reprogramming of WSNs. VSPIN provides a modular testing platform on the host system to plug-in and evaluate various incremental code update algorithms. The framework supports Avrdude, among the most popular Linux-based programming tools for AVR microcontrollers. Using VSPIN, we next present an incremental code update strategy to efficiently reprogram wireless sensor nodes. We adapt a linear space and quadratic time algorithm (Hirschberg\u27s Algorithm) for computing maximal common subsequences to build an edit map specifying an edit sequence required to transform the code running in a sensor network to a new code image. We then present a heuristic-based optimization strategy for efficient edit script encoding to reduce the edit map size. Finally, we present experimental results exploring the reduction in data size that it enables. The approach achieves reductions of 99.987% for simple changes, and between 86.95% and 94.58% for more complex changes, compared to full image transmissions - leading to significantly lower energy costs for wireless sensor network reprogramming. The third challenge focuses on enabling fast and reliable data storage in wireless sensor systems. A file storage system that is fast, lightweight, and reliable across device failures is important to safeguard the data that these devices record. A fast and efficient file system enables sensed data to be sampled and stored quickly and batched for later transmission. A reliable file system allows seamless operation without disruptions due to hardware, software, or other unforeseen failures. While flash technology provides persistent storage by itself, it has limitations that prevent it from being used in mission-critical deployment scenarios. Hybrid memory models which utilize newer non-volatile memory technologies, such as ferroelectric RAM (FRAM), can mitigate the physical disadvantages of flash. In this vein, we present the design and implementation of LoggerFS, a fast, lightweight, and reliable file system for wireless sensor networks, which uses a hybrid memory design consisting of RAM, FRAM, and flash. LoggerFS is engineered to provide fast data storage, have a small memory footprint, and provide data reliability across system failures. LoggerFS adapts a log-structured file system approach, augmented with data persistence and reliability guarantees. A caching mechanism allows for flash wear-leveling and fast data buffering. We present a performance evaluation of LoggerFS using a prototypical in-situ sensing platform and demonstrate between 50% and 800% improvements for various workloads using the FRAM write-back cache over the implementation without the cache
Fast recovery from node compromise in wireless sensor networks
Wireless Sensor Networks (WSNs) are susceptible to a wide range of security attacks in hostile environments due to the limited processing and energy capabilities of sensor nodes. Consequently, the use of WSNs in mission critical applications requires reliable detection and fast recovery from these attacks. While much research has been devoted to detecting security attacks, very little attention has been paid yet to the recovery task. In this paper, we present a novel mechanism that is based on dynamic network reclustering and node reprogramming for recovering from node compromise. In response to node compromise, the proposed recovery approach reclusters the network excluding compromised nodes; thus allowing normal network operation while initiating node recovery procedures. We propose a novel reclustering algorithm that uses 2-hop neighbourhood information for this purpose. For node reprogramming we propose the modified Deluge protocol. The proposed node recovery mechanism is both decentralized and scalable. Moreover, we demonstrate through its implementation on a TelosB-based sensor network testbed that the proposed recovery method performs well in a low-resource WSN.<br /
Cooperative Coded Data Dissemination for Wireless Sensor Networks
In this poster paper we present a data dissemination transmission abstraction
for over the air programming (OAP) protocol which is fundamentally different
from the previous hop by hop transmission protocols. Instead of imposing the
greedy requirement that at least one node in the ith hop receives all packets
before transmitting packets to the next hop and its neighbours, we take
advantage of the spatial diversity and broadcast nature of wireless
transmission to adopt a cooperative approach in which node broadcast whatever
packets it has received with the expectation that it will recover the lost
packets with high probability by overhearing the broadcast transmissions of its
neighbours. The use of coded transmissions ensures that this does not lead to
the broadcast storm problem. We validate the improved performance our of
proposed transmission scheme with respect to the previous state of the art OAP
protocols on a proof-of-concept two-hops TelosB wireless sensor network
testbed.Comment: This paper appears in: 2016 13th Annual IEEE International Conference
on Sensing, Communication, and Networking (SECON), London, 2016, pp. 1-
Middleware for Wireless Sensor Networks: An Outlook
In modern distributed computing, applications are rarely built directly atop operating system facilities, e.g., sockets. Higher-level middleware abstractions and systems are often employed to simplify the programmerâs chore or to achieve interoperability. In contrast, real-world wireless sensor network (WSN) applications are almost always developed by relying directly on the operating system.
Why is this the case? Does it make sense to include a middleware layer in the design of WSNs? And, if so, is it the same kind of software system as in traditional distributed computing? What are the fundamental concepts, reasonable assumptions, and key criteria guiding its design? What are the main open research challenges, and the potential pitfalls? Most importantly, is it worth pursuing research in this field?
This paper provides a (biased) answer to these and other research questions, preceded by a brief account on the state of the art in the field
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