Energy efficient communication models in wireless sensor and actor networks

Sensor nodes in a wireless sensor network (WSN) have a small, non-rechargeable power supply. Each message transmission or reception depletes a sensor node’s energy. Many WSN applications are ad-hoc deployments where a sensor node is only aware of its immediate neighbours. The lack of a predefined route path and the need to restrict the amount of communication that occurs within the application area impose constraints on WSNs not prevalent in other types of networks. An area of active research has been how to notify the central sink (or monitoring hub) about an event in real-time by utilising the minimum number of messages to route a message from a source node to the destination sink node. In this thesis, strategies to limit communication within a WSN application area, while ensuring that events are reported on and responded to in real-time, is presented. A solution based on modelling a WSN as a small world network and then transmitting an initialisation message (IM) on network start-up to create multiple route paths from any sensor node to one or more sinks is proposed. The reason for modelling a WSN as a small world network is to reduce the number of nodes required to re-transmit a message from a source sensor node to a sink. The purpose of sending an IM at network start-up is to ensure that communication within the WSN is minimised. When routing a message to a static sink, the nodes closest to the static sink receive a disproportionate number of messages, resulting in their energy being consumed earlier. The use of mobile sinks has been proposed but to our knowledge no studies have been undertaken on the paths these mobile sinks should follow. An algorithm to determine the optimum path for mobile sinks to follow in a WSN application area is described. The purpose of an optimum path is to allow more equitable usage of all nodes to transfer an event message to a mobile sink. The idea of using multiple static sinks placed at specific points in the small world model is broadened to include using multiple mobile sinks called actors to move within a WSN application area and respond to an event in real-time. Current coordination solutions to determine which actor(s) must respond to the event result in excessive message communication and limit the real-time response to an event. An info gap decision theory (IGDT) model to coordinate which actor or set of actors should respond to the event is described. A comparison of the small world routing (SWR) model against routing using flooding and gossiping shows that the SWR model significantly reduces the number of messages transmitted within the network. An analysis of the number of IMs transmitted and received at individual node level shows that prudent selection of the hop count (number of additional nodes required to route a message to sink) to a sink node will result in a reduced number of messages transmitted and received per node within the network. The use of the IGDT model results in a robust decision on the actor(s) chosen to respond to an event even when uncertainty about the location and available energy of other actor(s) exists.Thesis (PhD(Eng))--University of Pretoria, 2012.Electrical, Electronic and Computer Engineeringunrestricte

Simulation of wireless sensor node transmission over a multiple access channel

Smart Grids are emerging as a sustainable technology that can greatly improve the quality, cost and efficiency of electrical power distribution. Wireless communication technology, in particular wireless sensor networks, are being considered as a viable solution to Smart Grid communication requirements. Homes have multiple electrical appliances that may communicate concurrently. In addition, electrical appliances induce white noise that can interfere with the wireless signal. In this paper an indoor wireless sensor multiple access communication environ- ment is simulated based on the IEEE 802.15.4 wireless communication standard. An indoor wireless propagation model is implemented and the effects of signal interference on the wireless signal are examined

Re-using old cellphones for IoT applications

Abstract: In today’s world smartphones are the most used electronic device as they come with many capabilities that makes everyday life easier. The downside is that smartphones have very short life span and gets damaged easily, hence overtime they get discarded, which adds onto an existing problem of e-waste. Although thrown away, smartphones’ integrated circuits includes components which can be still re-used for other technologies. This project presents a way in which discarding of electronic components without re-use can be combated by making developments in the emerging IoT technology by re-use of smartphone components. To achieve this objective an Android App that requires no use interface and uses only Bluetooth and Wi-Fi components was developed. The App is responsible for giving web capabilities to a maximum of seven Bluetooth enabled sensors, so that the sensors can store their data on a cloud database

Smart homes : energy efficiency based on demand side management and game theoretic algorithm

Abstract: The smart home is an integral part of future energy management and control. The reduction of domestic energy consumption and improved energy efficiency of households will require intelligent systems that constantly monitor the household electricity usage and provides real-time updates to the user. This will lead to a bill reduction for households and energy efficiency. In this paper we investigate two concepts, namely; (i) the effect of a demand side management system, where a smart meter prototype was provided to each household depicting detailed and real-time information to the user, and (ii) a Game theoretic algorithm to manage and minimize the daily electricity expenditure and improve the energy efficiency of the domestic household. Computational results and data are provided and discussed that determine which system would work the best

Wireless sensor networks and advanced metering infrastructure deployment in smart grid

The increasing demand for has necessitated the introduction of information and communication technologies (ICT) in the development of the smart grid. Advanced Metering Infrastructure (AMI) and Wireless Sensor Networks (WSNs) are contributing technologies. In this paper, a review on AMI and WSN in the smart grid is carried out. Also, the introduction of WSNs with AMI in the in-home energy management system of the smart grid is also presented with challenges faced in the deployment of WSNs for the smart grid. The low power and low-cost nature of WSN has presented itself as a technology that can be used with AMI and smart home appliances in achieving home energy management within the great goal of the smart grid

Real time energy storage sharing with load scheduling : a lyapunov-based approach

Abstract: This paper studies energy storage sharing in a grid-connected residential microgrid, where a group of households with controllable loads and renewable generations cooperatively shares an energy storage. By exploiting delay tolerance of elastic loads, we develop a joint real time storage sharing and load management system that takes into consideration the operational constraints of the shared energy storage coupled with the time-varying load demands and stochastic renewable generations of all households, with the aim of minimizing the long term time-averaged energy costs of the households without reducing energy consumption. A Lyapunov-based online battery sharing control algorithm is designed to jointly optimize energy consumption, load scheduling and energy charging/discharging actions of individual households only based on current system states. The proposed online sharing algorithm enables the households to optimally utilize the shared battery and reschedule their delay tolerant loads in a distributed but coordinated fashion, while satisfying the time-varying energy consumption preference of each household. Numerical simulation results demonstrate that the low-complexity joint storage sharing and load scheduling algorithm serves the load demands of each household with a lower delay at a relatively low cost while facilitating a fair utilization of the shared energy among the households in terms of their energy contributions

Actor coordination using info-gap decision theory in wireless sensor and actor networks

Mobile, unmanned, power and resource-rich devices, called actors, deployed within a Wireless Sensor Network (WSN) application area, enable faster response times to events. Due to cost constraints, only a few actors can be placed within a WSN application area. Determining which actor or set of actors should respond to an event is important, because the correct decision will increase the event response time, and reduce energy expenditure. Since the mobile actors are widely dispersed over the application area, the actors' accurate location and energy details will not always be available. In this paper, we show that using info-gap decision theory to choose the correct actors to respond to an event when uncertainty about an actor's location and/or energy exists, ensures that the actors chosen can adequately respond to the event. The robustness of the decision choice of the set of actor(s) assigned to respond to an event means that all chosen actor(s) have sufficient energy to respond to the event in real-time.http://www.inderscience.com/browse/index.php?journalCODE=ijsnetai201

Internet of things data integrity

Abstract: Internet of Things is an internetwork where people interact with the environment via sensors and machines to perform physical activities remotely. IoT allows objects to be sensed and controlled remotely via internet such as changing the room temperature by controlling an air conditioner, switching on the lights in your apartment, using smart watches to gather information about your body health (blood pressure and heart beat rate) and sends it to your private doctor to monitor it and so on. Performing a research on issues faced with IoT, it was realized that most challenges were of privacy/confidentiality and data integrity. This project further conducts research on finding ways of securing information that is shared between two or more interactive IoT devices. The main objective of the project was to develop a strategy of securing the IoT technology world. The method that was proposed to provide data security and integrity was through cryptographic methods/security algorithms that require decent memory and equitable CPU processing power .There were three security methods that were focused on in this project i.e. RSA, AES and TDES algorithms. Each of the encryption/decryption methods were presented with their detailed design and functionality. The most suitable and better performing security algorithm for IoT technology was chosen according to the measures of time, memory and processing power. With the tests performed on the proposed security algorithms, AES encryption standard seemed to perform better than other security algorithms in terms computational time, memory consumption and the required processing power. The test results also showed that it has a large encryption/decryption key size which also means better protection for data. However through testing of the encryption methods there were shortcomings that were encountered such as inability of the security algorithms to provide authentication and encrypt different data formats such as video, picture and audio. The short comings will be further dealt with on the future work. The success of this research has potential impact on increasing the security of IoT internetwork which intern will increase the number of users in the IoT world

Design of a low cost Television White Space Z antenna

Abstract: The use of Television White Spaces (TVWS) for broadband communication has raised interest of late. In respect of rural areas, wireless is the only viable alternative for providing affordable telecommunications services. One limiting factor to the growth of wireless broadband penetration is the lack of available spectrum. White Spaces refer to regions of radio spectrum that are not used all the time in a specific geographical location. An assessment study on TV White Spaces availability in Malawi using affordable tools has been described and it was concluded that it is possible to assess the spectrum usage using low cost equipment. In this paper, the design aspects and the measured results of a low cost Television White Space Z antenna are described

Optimization of energy expenditure in smart homes under Time-of-Use pricing

Abstract: Growing peak demand has necessitated the introduction of Time-of-Use (TOU) pricing to Demand Side Management (DSM) in order to cause some peak demand to be shifted from peak to off-peak periods. Therefore, in this work, a Daily Maximum Energy Scheduling (DMES) - DSM technique is proposed. The DMES-DSM device is proposed to be installed into consumers’ smart meters and schedule energy consumption for smart appliances. The DMES–DSM technique was verified with real household data and shown to be capable of optimizing households’ monthly energy expenditure below approved national energy expenditure threshold and also offer Peak Demand Reduction (PDR). It offered the household considered an average monthly financial savings of 22.44% and 36.73% in summer and winter respectively on electricity bills. Utility can also benefit from the PDR for grid stability and sustainability. Also, the optimized consumption pattern differs only slightly from initial consumption pattern for enhanced consumer satisfaction