Many-to-many data aggregation scheduling in wireless sensor networks with two sinks

Traditionally, wireless sensor networks (WSNs) have been deployed with a single sink. Due to the emergence of sophisticated applications, WSNs may require more than one sink. Moreover, deploying more than one sink may prolong the network lifetime and address fault tolerance issues. Several protocols have been proposed for WSNs with multiple sinks. However, most of them are routing protocols. Differently, our main contribution, in this paper, is the development of a distributed data aggregation scheduling (DAS) algorithm for WSNs with two sinks. We also propose a distributed energy-balancing algorithm to balance the energy consumption for the aggregators. The energy-balancing algorithm first forms trees rooted at nodes which are termed virtual sinks and then balances the number of children at a given level to level the energy consumption. Subsequently, the DAS algorithm takes the resulting balanced tree and assigns contiguous slots to sibling nodes, to avoid unnecessary energy waste due to frequent active-sleep transitions. We prove a number of theoretical results and the correctness of the algorithms. Through simulation and testbed experiments, we show the correctness and performance of our algorithms

Constructing energy efficient bluetooth scatternets for wireless sensor networks

Cataloged from PDF version of article.The improvements in the area of wireless communication and micro-sensor technology have made the deployment of thousands, even millions, of low cost and low power sensor nodes in a region of interest a reality. After deploying sensor nodes in a target region of interest, which can be inaccessible by people, people can collect useful data from the region remotely. The sensor nodes use wireless communication and can collaborate with each other. However, sensor nodes are battery powered and therefore they have limited energy and lifetime. This makes energy as the main resource problem in sensor networks. The design process for sensor networks has to consider energy constraints as the main factor to extend the lifetime of the network. The wireless technology used for communication among sensor nodes can affect the lifetime of the network, since different technologies have different energy consumption parameters. Bluetooth, being low power and low cost, is a good candidate for being the underlying wireless connectivity technology for sensor networks tailored for various applications. But in order to build a large network of Bluetooth-enabled sensor nodes, we have to first form a Bluetooth scatternet. The topology of the Bluetooth scatternet affects the routing scheme to be used over that topology to collect and route informaton from sensor nodes to a base station. And routing scheme, in turn, affects how much energy is consumed during transport of information. Therefore, it is important to build a Bluetooth scatternet wisely to reduce and balance the energy consumption, hence extend the lifetime of a sensor network. In this thesis work, we propose a new Bluetooth scatternet formation algorithm to be used in Bluetooth-based sensor networks. Our algorithm is based on first computing a shortest path tree from the base station to all sensor nodes and then solving the degree constraint problem so that the degree of each node in the network is not greater than seven (a Bluetooth constraint). We also propose a balancing algorithm over the degree constrained tree to balance the energy consumption of the nodes that are closer to the base station. The closer nodes are the nodes that will consume more energy in the network since all traffic has to be forwarded over these nodes. Our simulation results show that our proposed algorithm improves the lifetime of the network by trying to reduce the energy consumed during data transfer and also by balancing the load among the nodes.Saginbekov, SainM.S

Efficient code dissemination in wireless sensor networks

Given the dynamic nature of the mission of a wireless sensor network (WSN), and of the environment in which it is usually deployed, network reprogramming is an important activity that enables the WSN to adapt to the mission and/or environment. One important component of a reprogramming protocol is the code dissemination and maintenance, during which a new code is propagated to relevant WSN nodes. Several dissemination protocols have been proposed, each with a specific objective in mind. Protocols such as Trickle minimize dissemination latency by periodically broadcasting advertisement messages at the expense of energy consumption, while protocols, e.g., Varuna, reduce the energy usage by broadcasting advertisement only when needed. In certain type of WSNs, such as event-based WSNs, Varuna has high code dissemination latency, while the energy consumption of Trickle does not improve in such WSNs. Further, the efficiency of Varuna drops drastically in the presence of asymmetric links. In this paper, we propose a new code dissemination protocol, called Triva, for event-based WSNs, by leveraging the properties of Trickle and Varuna. Our simulation and experimental results show that, for event-based WSNs, Triva outperforms Trickle and Varuna in terms of energy consumption and code dissemination latency respectively. Triva also outperforms Trickle and Varuna when there are unidirectional links in the network. We also show that Triva provides excellent results during bursty traffic in event-based WSNs. Triva is the first information dissemination protocol for event-based WSNs and that tolerates asymmetric links

Towards efficient stabilizing code dissemination in wireless sensor networks

One important component of network reprogramming is code dissemination (CD), when the updated program code is distributed to the relevant nodes. Very few CD protocols tolerate transient faults that corrupt the state and these faults can cause the old code to disseminate in the network. We propose two protocols called BestEffort-Repair and Consistent-Repair that transform fault-intolerant CD protocols into non-masking fault-tolerant protocols where, eventually, all nodes obtain the new code. We conduct experiments with both protocols on TelosB-like motes and over TOSSIM simulations to show their correctness and also their performance. We conduct a case study whereby both protocols are added to a state-of-the-art CD protocol, namely Varuna to evaluate their impact on Varuna. Our results show that (i) Varuna, which is fault-intolerant, is transformed into a stabilizing CD protocol; (ii) they induce low overhead on Varuna, and cause all nodes to eventually receive the new code. BestEffort-Repair is biased towards fast recovery, whereas Consistent-Repair attempts to reduce the number of erroneous downloads in the network. Our main contribution is the first corrector protocols that correct CD in the presence of transient faults

Efficient and reliable data dissemination and convergecast in Wireless Sensor Networks

With the availability of cheap sensor nodes now it is possible to use hundreds of nodes in a Wireless Sensor Network (WSN) application. Since then WSN applications have been being used in a wide range of applications, including environmental, industrial, military, health-care and indoor applications. WSNs are composed of sensor nodes, also known as motes, that are small in size, usually battery powered, and have limited memory and computing capabilities. As opposed to other wireless networks of more powerful nodes such as laptops, cellular phones, PDAs, etc., where communications can occur between any two nodes, in WSNs there are mainly two communication types: (i) broadcast, where a designated node, called a sink, disseminates data to all other nodes and (ii) convergecast, where all nodes send their generated data to the sink. After deploying sensor nodes in an area of interest, they are usually unattended for a long time. Since motes are battery powered, the energy conservation is of great importance. Furthermore, due to limited resources such as computing, memory and energy, harsh environmental conditions and buggy programs, wireless sensors may experience a number of different types of faults. Given the characteristics of sensor nodes and the environment they are deployed in, any WSN communication protocol and algorithm should be energy efficient and tolerant to faults. Several efficient communication protocols have been proposed so far. However, there are several aspects that has seen very little activity in the literature: (i) Handling transient faults and (ii) Dealing with two or more sinks. Therefore, in this thesis, we are proposing to address some of the issues that are still open. Specifically, we are planning to look at fault tolerance in data dissemination and the development of an infrastructure for two sinks. In this thesis, (i) we try to make data dissemination protocols resilient to faults that can corrupt values stored in the memory and messages by presenting two algorithms that when added to fault-intolerant dissemination protocols, make the code dissemination protocols fault-tolerant, (ii) we try to minimize drawbacks of existing code update maintenance algorithms by proposing a new algorithm that efficiently maintains code updates in WSNs, and (iii) we propose an efficient data aggregation convergecast scheduling algorithm for wireless sensor networks with two sinks

Many-to-many data aggregation scheduling in wireless sensor networks with two sinks

Abstract Traditionally, wireless sensor networks (WSNs) have been deployed with a single sink. Due to the emergence of sophisticated applications, WSNs may require more than one sink. Moreover, deploying more than one sink may prolong the network lifetime and address fault tolerance issues. Several protocols have been proposed for WSNs with multiple sinks. However, most of them are routing protocols. Differently, our main contribution, in this paper, is the development of a distributed data aggregation scheduling (DAS) algorithm for WSNs with two sinks. We also propose a distributed energy-balancing algorithm to balance the energy consumption for the aggregators. The energy-balancing algorithm first forms trees rooted at nodes which are termed virtual sinks and then balances the number of children at a given level to level the energy consumption. Subsequently, the DAS algorithm takes the resulting balanced tree and assigns contiguous slots to sibling nodes, to avoid unnecessary energy waste due to frequent active-sleep transitions. We prove a number of theoretical results and the correctness of the algorithms. Through simulation and testbed experiments, we show the correctness and performance of our algorithms

An Energy-Efficient Scatternet Formation Algorithm for Bluetooth-Based Sensor Networks

In this paper, we propose an energy-efficient scatternet formation algorithm for Bluetooth based sensor networks. The algorithm is based on first computing a shortest path tree from the base station to all sensor nodes and then solving the degree constraint problem so that the degree of each node in the network is not greater than seven, which is a Bluetooth constaint. In this way, less amount of energy is spent in each round of communication in the sensor network. The algorithm also tries to balance the load evenly on the highenergy consuming nodes which are the nodes that are close to the base station. In this way, the lifetime of the first dying node is also prolonged. We obtained promising results in the simulations

Efficient Data Aggregation in Wireless Sensor Networks with Multiple Sinks

A Wireless Sensor Network (WSN) is a network comprised of sensor nodes and a designated device called a sink to which nodes transmit their sensed data. Nodes are low-cost, battery-powered devices with limited memory and computational power. Usually WSNs are deployed with a single sink and left unattended for a long time. During this time sensor nodes, communication links between the nodes, and the sink may go down or crash due to energy depletion, harsh environment, or for some other reasons. If the sink crashes, then the network becomes useless as the sink will not be able to collect data from nodes. One way of making the network more reliable is to deploy networks with more than one sink. Existing efficient data aggregation protocols developed for WSNs with a single sink may not show the similar efficiency in WSNs with multiple sinks. In this paper, we first define the data aggregation problem in WSNs with multiple sinks, and then propose two data aggregation algorithms for a WSN with multiple sinks that minimize the number of data packet transmissions during data collection. The first one is based on a Minimum Spanning Tree algorithm and the second one is based on a Shortest Path Tree algorithm. Simulation results show the effectiveness of the proposed algorithms