Now showing 1 - 10 of 26
  • Publication
    Diversity & interoperability : wireless technologies in ambient assisted living
    Ambient Assisted Living (AAL) demands the seamless integration of a range of technologies such that the particular needs of the elderly may be met. Given the heterogeneity of the elderly population, in their needs and circumstances amongst others, this is a significant challenge. In essence, it demands that a disparate suite of technologies be deployed, integrated, managed and interacted with in a seamless and intuitive fashion. In this paper, how this heterogeneity may be managed is discussed. In particular, the use of ontologies and middleware are proposed as potential solutions to this heterogeneity problem.
      648
  • Publication
    An agent-based domestic electricity consumption advisory system
    This paper introduces an agent-based domestic electricity consumption advisory system. It reflects upon the diffculties of realizing the ubiquitous sensing vision which underpins such systems. It advocates the need for an effective middleware which will support the evolution of heterogeneous, distributed, collaborative intelligent sensing artifacts. To this end, it introduces the SIXTH Middleware.
      784
  • Publication
    Advantages of Dual Channel MAC for Wireless Sensor Networks
    Traditional low cost radios for wireless sensor networks operate with one frequency channel at any given time. However, recent advances in radio hardware for WSNs made available transceivers that can support two simultaneous channels. In this work, we investigate the benefits of using two parallel independent frequency channels at the MAC layer. In particular, the paper introduces a technique of Dual Channel Multiple Access with Adaptive Preamble (DCMA/AP). The protocol uses two separate frequencies for data and control packets to avoid the use of handshake mechanisms (e.g. RTS/CTS) in order to reduce energy consumption and packet delay. To address the hidden and exposed terminal problems, DCMA/AP enables a receiver to send a busy tone signal on the control channel to notify neighbors that an ongoing reception is in progress. As a result, packet collisions are nullified with an increase of node throughput. Furthermore, an adaptive preamble mechanism in DCMA/AP avoids secondary processes of node synchronization together with a reduction of idle listening of receiving nodes that are considered to be one of the major sources of energy consumption in wireless sensor networks. Finally, DCMA/AP introduces a mechanism of opportunistic crossover speeds up the process of packet forwarding by pre-announcing the successive candidate node intended to receive the packet.
      407
  • Publication
    Evaluation of energy-efficiency in lighting systems using sensor networks
    In modern energy aware buildings, lighting control systems are put in place so to maximise the energy-efficiency of the lighting system without effecting the comfort of the occupant. In many cases this involves utilising a set of presence sensors, with actuators, to determine when to turn on/off or dim lighting, when it is deemed necessary. Such systems are installed using standard tuning values statically fixed by the system installer. This can cause inefficiencies and energy wastage as the control system is never optimised to its surrounding environment. In this paper, we investigate a Wireless Sensor Network (WSN) as a viable tool that can help in analysing and evaluating the energy-efficiency of an existing lighting control system in a low-cost and portable solution. We introduce LightWiSe (LIGHTting evaluation through WIreless SEnsors), a wireless tool which aims to evaluate lighting control systems in existing office buildings. LightWiSe determines points in the control system that exhibit energy wastage and to highlight areas that can be optimised to gain a greater efficiency in the system. It will also evaluate the effective energy saving to be obtained by replacing the control system with a more judicious energy saving solution. During a test performed in an office space, with a number of different lighting control systems we could highlight a number of areas to reduce waste and save energy. Our findings show that each system tested can be optimised to achieve greater efficiency. LightWiSe can highlight savings in the region of 50% to 70% that are achievable through optimising the current control system or installing an alternative.
      2543
  • Publication
    On the RFID Wake-up Impulse for Multi-hop Sensor Networks
    Communication protocols for wireless sensor networks reduce the energy consumption by duty cycling the node activity and adopting a periodic sleeping scheduling. This approach often results in idle listening and therefore energy dissipated for listening to a channel free from packet transmitted. Duty cycling trades-off energy consumption due to idle listening and high end-to-end delay. Proposed solutions mitigate this issue for example through extra low-power radio components (wake-up radio) that listen to the radio and wake-up the node if some channel activity is sensed. These extra components also consume some energy to listen to the channel. In contrast, we propose an on-demand wake-up capability, namely RFIDimpulse, which is achieved through using an off-the-shelf batteryless RFID tag attached to each sensor node that is also provided with RFID reader capability. Because modern RFID techniques can trigger all the neighbouring tags at once or pinpoint a particular tag, RFIDimpluse provides both unicast and multicast capability. RFIDimpulse allows eventdriven communication and eliminates node idle listening.
      361
  • Publication
    Dynamic reassignment of aggregation point for network load balancing
    Some wireless sensor network applications forward data to a central aggregation point (AP) that is responsible for processing, aggregating, and relaying information to the base station. For example one node in a body sensor network is responsible for aggregating data and then forwarding only useful information to an external ambient network. This procedure leads to asymmetry in the AP node energy consumption due to (1) higher forwarding activity for nodes in the vicinity of the AP and (2) higher AP activity relative to nodes. Existing approaches of load and energy consumption balancing employ either suboptimal periodical route changes or random AP rotations. In contrast, we propose a novel technique1 to enable a dynamic reassignment of the sensor AP according to a novel cost function that is based on relevant node energy metrics. We show that the technique lead to a network lifetime extension up to 50% for applications, such as medical, that require power-intensive tasks at the AP and for high traffic applications.
      110
  • Publication
    Multi-hop RFID wake-up radio : design, evaluation and energy tradeoffs
    Energy efficiency is a central challenge in battery operated sensor networks. Current energy-efficient mechanisms employ either duty cycling, which reduces idle listening but does not eliminate it, or low power wake-up radio, which adds complexity and cost to the sensor platform. In this paper, we propose a novel mechanism called RFIDImpulse that uses RFID technology as an out-of-band wake-up channel for sensor networks. RFIDImpulse is an on-demand mechanism that enables nodes to sleep until they have to send or receive packets. It relies on IEEE 802.15.4 radio to emulate an RFID reader at a sender node, and on an off-the-shelf RFID tag attached to the external interrupt pin of each sensor node. The sender can simply activate the receiver’s tag before sending it data packets. This setup enables both radio and microcontroller to go into deep sleep mode until they need to be active. We develop an analytical model to evaluate the energy tradeoffs of RFIDImpulse, and then evaluate the mechanism against BMAC and IEEE 802.15.4 in high and low traffic scenarios. The results confirm that RFIDImpulse reduces the energy consumption relative to both protocols for low and medium traffic scenarios, and they reveal the thresholds for adaptive activation of RFIDImpulse based on traffic load.
      1145Scopus© Citations 32
  • Publication
    Generating power footprints without appliance interaction : an enabler for privacy intrusion
    Appliance load monitoring (ALM) systems are systems capable of monitoring appliances’ operation within a building using a single metering point. As such, they uncover information on occupants’ activities of daily living and subsequently an exploitable privacy leak. Related work has shown monitoring accuracies higher than 90% ̇ achieved by ALM systems, yet requiring interaction with appliances for system calibration. In the context of external privacy intrusion, ALM systems have the following obstacles for system calibration: (1) type and model of appliances inside the monitored building are entirely unknown; (2) appliances cannot be operated to record power footprints; and (3) ground truth data is not available to fine- tune algorithms. Within this work, we focus on monitoring those appliances from which we can infer occupants’ activities. Without appliance interaction, appliances’ profiling is realised via automated capture and analysis of shapes, steady-state durations, and occurrence patterns of power loads. Such automated process produces unique power footprints, and naming is realised using heuristics and known characteristics of typical home equipment. Data recorded within a kitchen area and one home illustrates the various processing steps, from data acquisition to power footprint naming.
      636Scopus© Citations 2
  • Publication
    The clarity modular ambient health and wellness measurement platform
    Emerging healthcare applications can benefit enormously from recent advances in pervasive technology and computing. This paper introduces the CLARITY Modular Ambient Health and Wellness Measurement Platform, which is a heterogeneous and robust pervasive healthcare solution currently under development at the CLARITY Center for Sensor Web Technologies. This intelligent and context-aware platform comprises the Tyndall Wireless Sensor Network prototyping system, augmented with an agent-based middleware and frontend computing architecture. The key contribution of this work is to highlight how interoperability, expandability, reusability and robustness can be manifested in the modular design of the constituent nodes and the inherently distributed nature of the controlling software architecture.
    Scopus© Citations 5  869