9,800 research outputs found
Synchronous and Concurrent Transmissions for Consensus in Low-Power Wireless
With the emergence of the Internet of Things, autonomous vehicles and the Industry 4.0, the need for dependable yet adaptive network protocols is arising. Many of these applications build their operations on distributed consensus. For example, UAVs agree on maneuvers to execute, and industrial systems agree on set-points for actuators.Moreover, such scenarios imply a dynamic network topology due to mobility and interference, for example. Many applications are mission- and safety-critical, too.Failures could cost lives or precipitate economic losses.In this thesis, we design, implement and evaluate network protocols as a step towards enabling a low-power, adaptive and dependable ubiquitous networking that enables consensus in the Internet of Things. We make four main contributions:- We introduce Orchestra that addresses the challenge of bringing TSCH (Time Slotted Channel Hopping) to dynamic networks as envisioned in the Internet of Things. In Orchestra, nodes autonomously compute their local schedules and update automatically as the topology evolves without signaling overhead. Besides, it does not require a central or distributed scheduler. Instead, it relies on the existing network stack information to maintain the schedules.- We present A2 : Agreement in the Air, a system that brings distributed consensus to low-power multihop networks. A2 introduces Synchrotron, a synchronous transmissions kernel that builds a robust mesh by exploiting the capture effect, frequency hopping with parallel channels, and link-layer security. A2 builds on top of this layer and enables the two- and three-phase commit protocols, and services such as group membership, hopping sequence distribution, and re-keying.- We present Wireless Paxos, a fault-tolerant, network-wide consensus primitive for low-power wireless networks. It is a new variant of Paxos, a widely used consensus protocol, and is specifically designed to tackle the challenges of low-power wireless networks. By utilizing concurrent transmissions, it provides a dependable low-latency consensus.- We present BlueFlood, a protocol that adapts concurrent transmissions to Bluetooth. The result is fast and efficient data dissemination in multihop Bluetooth networks. Moreover, BlueFlood floods can be reliably received by off-the-shelf Bluetooth devices such as smartphones, opening new applications of concurrent transmissions and seamless integration with existing technologies
Atomic-SDN: Is Synchronous Flooding the Solution to Software-Defined Networking in IoT?
The adoption of Software Defined Networking (SDN) within traditional networks
has provided operators the ability to manage diverse resources and easily
reconfigure networks as requirements change. Recent research has extended this
concept to IEEE 802.15.4 low-power wireless networks, which form a key
component of the Internet of Things (IoT). However, the multiple traffic
patterns necessary for SDN control makes it difficult to apply this approach to
these highly challenging environments. This paper presents Atomic-SDN, a highly
reliable and low-latency solution for SDN in low-power wireless. Atomic-SDN
introduces a novel Synchronous Flooding (SF) architecture capable of
dynamically configuring SF protocols to satisfy complex SDN control
requirements, and draws from the authors' previous experiences in the IEEE EWSN
Dependability Competition: where SF solutions have consistently outperformed
other entries. Using this approach, Atomic-SDN presents considerable
performance gains over other SDN implementations for low-power IoT networks. We
evaluate Atomic-SDN through simulation and experimentation, and show how
utilizing SF techniques provides latency and reliability guarantees to SDN
control operations as the local mesh scales. We compare Atomic-SDN against
other SDN implementations based on the IEEE 802.15.4 network stack, and
establish that Atomic-SDN improves SDN control by orders-of-magnitude across
latency, reliability, and energy-efficiency metrics
Allocation of Heterogeneous Resources of an IoT Device to Flexible Services
Internet of Things (IoT) devices can be equipped with multiple heterogeneous
network interfaces. An overwhelmingly large amount of services may demand some
or all of these interfaces' available resources. Herein, we present a precise
mathematical formulation of assigning services to interfaces with heterogeneous
resources in one or more rounds. For reasonable instance sizes, the presented
formulation produces optimal solutions for this computationally hard problem.
We prove the NP-Completeness of the problem and develop two algorithms to
approximate the optimal solution for big instance sizes. The first algorithm
allocates the most demanding service requirements first, considering the
average cost of interfaces resources. The second one calculates the demanding
resource shares and allocates the most demanding of them first by choosing
randomly among equally demanding shares. Finally, we provide simulation results
giving insight into services splitting over different interfaces for both
cases.Comment: IEEE Internet of Things Journa
Fast Desynchronization For Decentralized Multichannel Medium Access Control
Distributed desynchronization algorithms are key to wireless sensor networks
as they allow for medium access control in a decentralized manner. In this
paper, we view desynchronization primitives as iterative methods that solve
optimization problems. In particular, by formalizing a well established
desynchronization algorithm as a gradient descent method, we establish novel
upper bounds on the number of iterations required to reach convergence.
Moreover, by using Nesterov's accelerated gradient method, we propose a novel
desynchronization primitive that provides for faster convergence to the steady
state. Importantly, we propose a novel algorithm that leads to decentralized
time-synchronous multichannel TDMA coordination by formulating this task as an
optimization problem. Our simulations and experiments on a densely-connected
IEEE 802.15.4-based wireless sensor network demonstrate that our scheme
provides for faster convergence to the steady state, robustness to hidden
nodes, higher network throughput and comparable power dissipation with respect
to the recently standardized IEEE 802.15.4e-2012 time-synchronized channel
hopping (TSCH) scheme.Comment: to appear in IEEE Transactions on Communication
Random Access Protocols for Massive MIMO
5G wireless networks are expected to support new services with stringent
requirements on data rates, latency and reliability. One novel feature is the
ability to serve a dense crowd of devices, calling for radically new ways of
accessing the network. This is the case in machine-type communications, but
also in urban environments and hotspots. In those use cases, the high number of
devices and the relatively short channel coherence interval do not allow
per-device allocation of orthogonal pilot sequences. This article motivates the
need for random access by the devices to pilot sequences used for channel
estimation, and shows that Massive MIMO is a main enabler to achieve fast
access with high data rates, and delay-tolerant access with different data rate
levels. Three pilot access protocols along with data transmission protocols are
described, fulfilling different requirements of 5G services
Paxos Made Wireless: Consensus in the Air
Many applications in low-power wireless networks require complex coordination between their members. Swarms of robots or sensors and actuators in industrial closed-loop control need to coordinate within short periods of time to execute tasks. Failing to agree on a common decision can cause substantial consequences, like system failures and threats to human life. Such applications require consensus algorithms to enable coordination. While consensus has been studied for wired networks decades ago, with, for example, Paxos and Raft, it remains an open problem in multi-hop low-power wireless networks due to the limited resources available and the high cost of established solutions.This paper presents Wireless Paxos, a fault-tolerant, network-wide consensus primitive for low-power wireless networks. It is a new flavor of Paxos, the most-used consensus protocol today, and is specifically designed to tackle the challenges of low-power wireless networks. By building on top of concurrent transmissions, it provides low-latency, high reliability, and guarantees on the consensus. Our results show that Wireless Paxos requires only 289 ms to complete a consensus between 188 nodes in testbed experiments. Furthermore, we show that Wireless Paxos\ua0stays consistent even when injecting controlled failures
Concurrent Transmissions for Multi-hop Bluetooth 5
Bluetooth is an omnipresent communication technology, available on billions of connected devices today.While it has been traditionally limited to peer-to-peer and star network topology, the recent Bluetooth 5 standard introduces new operating modes to allow for increased reliability and Bluetooth Mesh supports multi-hop networking based on message flooding.In this paper, we present BlueFlood.It adapts concurrent transmissions, as introduced by Glossy, to Bluetooth.The result is fast and efficient network-wide data dissemination in multi-hop Bluetooth networks.Moreover, we show that BlueFlood floods can be reliably received by off-the-shelf Bluetooth devices such as smart phones, opening new applications of concurrent transmissions and seamless integration with existing technologies. We present an in-depth experimental feasibility study of concurrent transmissions over Bluetooth PHY in a controlled environment.Further, we build a small-scale testbed where we evaluate BlueFlood in real-world settings of a residential environment.We show that\ua0BlueFlood achieves 99% end-to-end delivery ratio in multi-hop networks with a duty cycle of 0.13% for 1-second intervals
Coordination and Self-Adaptive Communication Primitives for Low-Power Wireless Networks
The Internet of Things (IoT) is a recent trend where objects are augmented with computing and communication capabilities, often via low-power wireless radios. The Internet of Things is an enabler for a connected and more sustainable modern society: smart grids are deployed to improve energy production and consumption, wireless monitoring systems allow smart factories to detect faults early and reduce waste, while connected vehicles coordinate on the road to ensure our safety and save fuel. Many recent IoT applications have stringent requirements for their wireless communication substrate: devices must cooperate and coordinate, must perform efficiently under varying and sometimes extreme environments, while strict deadlines must be met. Current distributed coordination algorithms have high overheads and are unfit to meet the requirements of today\u27s wireless applications, while current wireless protocols are often best-effort and lack the guarantees provided by well-studied coordination solutions. Further, many communication primitives available today lack the ability to adapt to dynamic environments, and are often tuned during their design phase to reach a target performance, rather than be continuously updated at runtime to adapt to reality.In this thesis, we study the problem of efficient and low-latency consensus in the context of low-power wireless networks, where communication is unreliable and nodes can fail, and we investigate the design of a self-adaptive wireless stack, where the communication substrate is able to adapt to changes to its environment. We propose three new communication primitives: Wireless Paxos brings fault-tolerant consensus to low-power wireless networking, STARC is a middleware for safe vehicular coordination at intersections, while Dimmer builds on reinforcement learning to provide adaptivity to low-power wireless networks. We evaluate in-depth each primitive on testbed deployments and we provide an open-source implementation to enable their use and improvement by the community
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