Design and analysis of adaptive hierarchical low-power long-range networks

A new phase of evolution of Machine-to-Machine (M2M) communication has started where vertical Internet of Things (IoT) deployments dedicated to a single application domain gradually change to multi-purpose IoT infrastructures that service different applications across multiple industries. New networking technologies are being deployed operating over sub-GHz frequency bands that enable multi-tenant connectivity over long distances and increase network capacity by enforcing low transmission rates to increase network capacity. Such networking technologies allow cloud-based platforms to be connected with large numbers of IoT devices deployed several kilometres from the edges of the network. Despite the rapid uptake of Long-power Wide-area Networks (LPWANs), it remains unclear how to organize the wireless sensor network in a scaleable and adaptive way. This paper introduces a hierarchical communication scheme that utilizes the new capabilities of Long-Range Wireless Sensor Networking technologies by combining them with broadly used 802.11.4-based low-range low-power technologies. The design of the hierarchical scheme is presented in detail along with the technical details on the implementation in real-world hardware platforms. A platform-agnostic software firmware is produced that is evaluated in real-world large-scale testbeds. The performance of the networking scheme is evaluated through a series of experimental scenarios that generate environments with varying channel quality, failing nodes, and mobile nodes. The performance is evaluated in terms of the overall time required to organize the network and setup a hierarchy, the energy consumption and the overall lifetime of the network, as well as the ability to adapt to channel failures. The experimental analysis indicate that the combination of long-range and short-range networking technologies can lead to scalable solutions that can service concurrently multiple applications

Gossip Algorithms for Distributed Signal Processing

Gossip algorithms are attractive for in-network processing in sensor networks because they do not require any specialized routing, there is no bottleneck or single point of failure, and they are robust to unreliable wireless network conditions. Recently, there has been a surge of activity in the computer science, control, signal processing, and information theory communities, developing faster and more robust gossip algorithms and deriving theoretical performance guarantees. This article presents an overview of recent work in the area. We describe convergence rate results, which are related to the number of transmitted messages and thus the amount of energy consumed in the network for gossiping. We discuss issues related to gossiping over wireless links, including the effects of quantization and noise, and we illustrate the use of gossip algorithms for canonical signal processing tasks including distributed estimation, source localization, and compression.Comment: Submitted to Proceedings of the IEEE, 29 page

CLUSTERED DATA DIFFUSION ROUTING PROTOCOL FOR LARGE-SCALE WIRELESS SENSOR NETWORKS

One of the major challenges in the implementation of WSNs is to prolong the lifetime of the energy source in the sensor nodes. This can be achieved through designing energy-efficient routing protocol. Energy-efficient routing protocol enables WSNs to stay in operation for a long time by managing communication between the sensor nodes and the sink. In addition the routing protocol can handle a large number of sensor nodes in energy-efficient manner utilizing multihop communications among the sensors. Four existing routing protocols performance were analyzed using J-Sim simulator. Results obtained from the performance analysis show that the Directed Diffusion (DD), creates a large amount of overhead when broadcasting a query message to the whole network. This causes huge amount of energy consumption, which reduces WSNs lifetime. Low Energy Adaptive Clustering Hierarchy (LEACH) routing protocol, which assumes one-hop communication range from the sink node is not scalable for large-scale WSNs. To enhance the way the data can be gathered in query-driven data reporting method, a cluster-based data diffusion routing protocol for large-scale wireless sensor networks has been proposed. In the proposed method, the sink node sends the interest message unicastly, only to the cluster heads. In addition, multihop communication between the cluster heads for sending the interest, and receiving the data packets back from the source node has been used. The results obtained have been analyzed and compared with DD and PCDD protocols as well as with other works, in which some enhancements over DD were made using different approaches. The overall results using different metrics have shown that, the proposed protocol outperforms DD and PCDD in saving the energy . The improvement of CDD in saving the energy is between 50% and 63.64% while comparing it to DD and, 8% and 42.8% compared to PCDD, for the fixed density scenario. For the fixed area scenario the improvement is up to 29.4% and at least 15% while comparing CDD to PCDD and up to 63.1% and at least 26.1% while comparing it to DD. The proposed clustering data diffusion method also was extended to handle a combination of mobile and static nodes, and user’s (sink’s) mobility as well. It improved the coverage of the sensor network and for applications which need some movements of the sink node in order to gather data by sending the query message to the sensor field. A performance analysis for the extended protocol was conducted, and a significant energy saving was achieved especially in denser networks

Fast Convergence in Self-stabilizing Wireless Networks.

International audienceThe advent of large scale multi-hop wireless networks highlights problems of fault tolerance and scale in distributed systems, motivating designs that autonomously recover from transient faults and spontaneous reconfigurations. Self-stabilization provides an elegant solution for recovering from such faults. We present a complexity analysis for a family of self-stabilizing vertex coloring algorithms in the context of multi-hop wireless networks. Such "coloring" processes are used in several protocols for solving many different issues (clustering, synchronizing...). Overall, our results show that the actual stabilization time is much smaller than the upper bound provided by previous studies. Similarly, the height of the induced DAG is much lower than the linear dependency on the size of the color domain (that was previously announced). Finally, it appears that symmetry breaking tricks traditionally used to expedite stabilization are in fact harmful when used in networks that are not tightly synchronized

Energy Scaling Laws for Distributed Inference in Random Fusion Networks

The energy scaling laws of multihop data fusion networks for distributed inference are considered. The fusion network consists of randomly located sensors distributed i.i.d. according to a general spatial distribution in an expanding region. Among the class of data fusion schemes that enable optimal inference at the fusion center for Markov random field (MRF) hypotheses, the scheme with minimum average energy consumption is bounded below by average energy of fusion along the minimum spanning tree, and above by a suboptimal scheme, referred to as Data Fusion for Markov Random Fields (DFMRF). Scaling laws are derived for the optimal and suboptimal fusion policies. It is shown that the average asymptotic energy of the DFMRF scheme is finite for a class of MRF models.Comment: IEEE JSAC on Stochastic Geometry and Random Graphs for Wireless Network

Comparison of Two Self-organization and Hierarchical Routing Protocols for Ad Hoc Networks

International audienceIn this article, we compare two self-organization and hierarchical routing protocols for ad hoc networks. These two protocols apply the reverse approach from the classical one, since they use a reactive routing protocol inside the clusters and a proactive routing protocol between the clusters. We compare them regarding the cluster organization they provide and the routing that is then performed over it. This study gives an idea of the impact of the use of recursiveness and of the partition of the DHT on self-organization and hierarchical routing in ad hoc networks

The Design of Medium Access Control (MAC) Protocols for Energy Efficient and QoS Provision in Wireless Sensor Networks

This thesis work focuses on innovative design of media access control (MAC) protocols in wireless sensor networks (WNSs). The characteristics of the WSN inquire that the network service design considers both energy efficiency and the associated application requirement. However, most existing protocols address only the issue of energy efficiency. In this thesis, a MAC protocol has been proposed (referred to as Q-MAC) that not only minimized the energy consumption in multi-hop WSNs, but also provides Quality of Service (QoS) by differentiating network services based on priority levels prescribed by different applications. The priority levels reflect the state of system resources including residual energy and queue occupancies. Q-MAC contains both intra- and inter- node arbitration mechanisms. The intra-node packet scheduling employs a multiple queuing architectures, and applies a scheduling scheme consisting of packet classification and weighted arbitration. We introduce the Power Conservation MACAW (PC-MACAW), a power-aware scheduling mechanism which, together with the Loosely Prioritized Random Access (LPRA) algorithm, govern the inter-node scheduling. Performance evaluation are conducted between Q-MAC and S-MAC with respect to two performance metrics: energy consumption and average latency. Simulation results indicate Q-MAC achieves comparable performance to that of S-MAC in non-prioritized traffic scenarios. When packets with different priorities are introduced, Q-MAC yields noticeable average latency differentiations between the classes of service, while preserving the same degree of energy consumption as that of S-MAC. Since the high density nature of WSN may introduce heavy traffic load and thus consume large amount of energy for communication, another MAC protocol, referred to as the Deployment-oriented MAC (D-MAC)has been further proposed. D-MAC minimalizes both sensing and communication redundancy by putting majority of redundant nodes into the sleep state. The idea is to establish a sensing and communication backbone covering the whole sensing field with the least sensing and communication redundancy. In specific, we use equal-size rectangular cells to partition the sensing field and chose the size of each cell in a way such that regardless of the actual location within the cell, a node can always sense the whole cell and communicate with all the nodes in neighboring cells. Once the sensing field has been partitioned using these cells, a localized Location-aware Selection Algorithm (LSA) is carried out to pick up only one node within each cell to be active for a fixed amount of period. This selection is energy-oriented, only nodes with a maximum energy will be on and the rest of nodes will be put into the sleep state once the selection process is over. To balance the energy consumption, the selection algorithm is periodically conducted until all the nodes are out of power. Simulation results indicated that D-MAC saves around 80% energy compared to that of S-MAC and Q-MAC, while maintaining 99% coverage. D-MAC is also superior to S-MAC and Q-MAC in terms of average latency. However, the use of GPS in D-MAC in identifying the nodes within the same cell, would cause extra cost and complexity for the design of sensor nodes

Optimization of a Self-Stabilizing Role Assignment Algorithm for Actuator/Sensor Networks

La tesi si pone come obiettivo quello di proporre un algoritmo ottimizzato per l'assegnamento di ruoli nelle reti di sensori e attuatori. L'algoritmo è costituito da uno stack ti protocolli self-stabilizing che basa direttamente sull'interfaccia radio. Partendo dal basso lo Spanning Tree struttura la rete ad albero eleggendo dunque un root node. Basandosi su questa struttura il secondo livello dello stack implementa un paradigma di comunicazione gerarchico di tipo publish/subscribe, tramite cui ogni nodo notifica verso il root node le proprie funzionalità. In cima allo stack il Role Assignment analizza i ruoli richiesti dalle applicazioni per poter girare e, dinamicamente, provvede ad assegnarli ai nodi in base alle loro funzionalità. La tesi espone dunque l'implementazione dell'algoritmo per Network Simulator 2 (NS2) e i grafici ottenuti, riferenti agli indici di maggiore interesse