[ Slides Directory Listing | Papers ]
Deluge: Data
Dissemination for Network Reprogramming at Scale - Adam Chlipala, Jonathan
Hui, Gil Tolle
In this paper, we present Deluge, a reliable data
dissemination protocol for propagating large amounts of data (i.e. more
than can fit in RAM) from one or more source nodes to all other nodes over
a multihop, wireless sensor network. To achieve robustness to lossy
communication and node failures, we adopt an epidemic approach.
Representing the data object as a set of mixed-sized pages provides a
manageable unit of transfer which supports spatial multiplexing and pro-
visions for incremental upgrades. Due to the large data size, we identify
a set of possible optimizations and evaluate their effectiveness. We
demonstrate that the Deluge algorithm reliably dis- tributes data across
an increasingly sized multi-hop network while maintaining a constant
amount of local state. We also demonstrate that the energy required to
distribute this data is within the allowable per-mote energy budget.
Future directions include new methods for contention management and more
effective power scheduling.
DuraNet:
Energy-Efficient Durable Slot-Free Power Scheduling - Terence Tong, David
Molnar, Alec Woo
We present an effective distributed power scheduling
algorithm for mixed, low bandwidth, many to one data collection sensor
network applications. DuraNet reduces energy consumption by avoiding
collision and overhearing while having nodes sleep most of the time. Because
that it is hard to achieve global time synchronization while nodes are
sleeping, DuraNet avoids the traditional approach where global hard bound
time slots are assigned to nodes for communication. Instead, there is no
notion of global time in DuraNet. Nodes allocate schedules for each link
based on contention in a schedule formation phase, then re-use these
schedules for a long period of time. By doing so, DuraNet is able to adapt
to density, while providing significant energy savings. Given a route tree
topology, DuraNet is also able to avoid congestion due to buffer queue
overflow by careful scheduling. We compare our algorithm to low power
listening and classic CSMA through extensive simulation in TOSSIM[12]. We
find that DuraNet achieves significant energy reduction over classic CSMA
and low power listening, while providing similar end-to-end reliability.
DRAFT:
Self-Tuning Energy-Aware Multichannel (STEAM) Scheduling - Umesh
Shankar
Lessons
From A Sensor Network Expedition - Rob Szewczyk, Joe
Polastre,
Alan Mainwaring, David Culler
Habitat monitoring is an important driving application for
wireless sensor networks (WSNs). Although researchers anticipate some
challenges arising in the real-world deployments of sensor networks, a
number of problems can be discovered only through experience. This paper
evaluates a sensor network system described in an earlier work and
presents a set of experiences from a four month long deployment on a
remote island on the coast of Maine. We present an in-depth analysis of
the environmental and node health data. The close integration of WSNs with
their environment provides biological data at densities previous
impossible; however, we show that the sensor data is also useful for
predicting system operation and network failures. Based on over one
million data and health readings, we analyze the node and network design
and develop network reliability profiles and failure models.
Node-level
Representation and System Support for Network Programming - Jaein
Jeong
One problem of the current network programming
implementation in TinyOS 1.1 is that it takes much longer than the traditional
in-system-programming due to the slow radio connection. We extended the
implementation so that it uses the history of the previous version to
reduce the transmission time. For a small amount of change in the source
code, we achieved around 3.5 times of the speed-up. And for the case where
no code blocks were shared, our implementation worked as much as the
current implementation.
DTNLite:
A Reliable Data Transfer Architecture for Sensor Networks - Rabin
Patra, Sergiu
Nedevschi
We present a network architecture, DTNLite, for reliable
message delivery in sensor networks facing problems of high mobility,
frequent disconnections and unreliable nodes . It is based on the DTN(
Delay Tolerant Networking) architecture and its main features are
asynchronous message delivery combined with custody transfer on an overlay
network on sensor motes. We present an implementation of this architecture
for the TinyOS platform targeting data collection applications. We also
explore the various issues in reliable custody transfer and investigate
the particular issue of querying and selection of custody hops in detail.
Our simulation results show that selection criteria that use energy or
delay as metrics are able to profitably exploit the asymmetries in the
network.
Trickle: A Self
Regulating Algorithm for Code Propagation and Maintenance in Wireless
Sensor Networks - Phil
Levis, Neil Patel, Scott Shenker, David Culler
We present Trickle, an algorithm for propagating and maintaining code
updates in wireless sensor networks. Trickle uses a “polite gossip”
policy, where nodes periodically broadcast a code summary to local
neighbors but stay quiet if they have recently heard a summary identical
to theirs. When a node hears an older summary than its own, it broadcasts
an update. Instead of flooding a network with packets, the algorithm
controls the send rate so each node hears a small trickle of packets, just
enough to stay up to date. We first analyze Trickle using an idealized
single-cell network model, with perfect synchronization and no packet
loss. Progressively relaxing these assumptions, we evaluate the algorithm
in simulation, first without synchronization, then in the presence of
loss, and finally in the multi-cell case. We validate these simulation
results with empirical data from a real-world deployment. We show that
Trickle scales well, with the aggregate network transmission count
increasing as a logarithm of cell density. We show that by dynamically
adjusting listening periods, Trickle can rapidly propagate new code,
taking on the order of seconds, while keeping maintenance costs on the
order of a few sends per hour per node.
Tython:
Scripting TOSSIM (WIP) - Michael Demmer, Philip Levis
Flexible
Power Scheduling for Sensor Networks - Barbara Hohlt, Lance Doherty,
Eric Brewer
We propose a distributed on-demand power-management protocol for
collecting data in sensor networks. The protocol aims to reduce power
consumption while supporting fluctuating demand in the network and provide
local routing information and synchronicity without global control. Energy
savings are achieved by powering down nodes during idle times identified
through dynamic scheduling. We present a real implementation on wireless
sensor nodes based on a novel, two-level architecture. We evaluate our
approach through measurements and simulation, and show how the protocol
allows adaptive scheduling and enables a smooth trade-off between energy
savings and latency. An example current measurement shows an energy
savings of 83% on an intermediate node.