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As devices are expected to be aware of their environment, the challenge becomes how to accommodate these abilities with the power constraints which plague modern mobile devices. We present a framework for an embedded approach to context recognition which reduces power consumption. This is accomplished by identifying class-sensor dependencies, and using prediction methods to identify likely future...
In this paper, a new type of collaboration in wireless sensor networks (WSN) is suggested that exploits array processing algorithms to improve the reception of a signal. For receive collaboration, the transmission power during intra-cluster transmissions decreases at the expense of increasing the inter-cluster communications. It is shown that, as a result of using receive collaboration, the destination...
The authors detail the alignment prediction approach-a time-series-estimation technique applicable to both numeric and nonnumeric data-and compare it to four other prediction approaches to determine context-prediction accuracy in ubiquitous computing environments.
We study closed-loop feedback based approaches to distributed adaptive transmit beamforming in wireless sensor networks. For a global random search scheme we discuss the impact of the transmission distance on the feasibility of the synchronisation approach. Additionally, a quasi novel method for phase synchronisation of distributed adaptive transmit beam-forming in wireless sensor networks is presented...
We present three approaches for algorithmic improvements on distributed adaptive transmit beamforming in wireless sensor networks. These algorithms reduce the time to synchronise carrier signals among nodes compared to the global random search approaches commonly applied to this problem. For a local random search heuristic we provide an asymptotic bounds on the optimisation time. All approaches are...
We study a closed-loop feedback based approach to distributed adaptive transmit beamforming in wireless sensor networks. Three algorithms to achieve sufficient phase synchronisation of carrier signals are considered. In particular, we study the impact of normal and uniform distributions for the phase alteration probability on the performance of the synchronisation process. Both distributions are studied...
With collaborative transmission we propose a novel transmission scheme that utilizes constructive interference between transmitted signals of wireless sensor nodes. Similar to cooperative transmission approaches we are able to drastically extend the transmission range of a wireless sensor network. We show that synchronization of received signal components is feasible without inter-node communication...
We discuss impacts of the prediction search space size on accuracy and robustness of context prediction approaches. Additionally, the impact on error detection and correction capabilities are considered. Conclusions are experimentally verified in a realistic ubiquitous setting.
We propose an audio-based mechanism for device authentication. The method is feasible with low-end microphones and can be extended to further UbiComp application domains as improved location estimation of sensor nodes or alarming. Measurement results obtained in a preparatory study demonstrate the performance of the approach.
In sensor networks different types of sensors are used to capture events, recognize contexts, derive states of objects or monitor processes within application scenarios. We envision the use of the presented technology in areas that are very complex, e.g. in industrial applications. The presented system uses sensor information from wireless sensor nodes that are forwarded and aggregated in an information...
Context prediction mechanisms proactively provide information on future contexts. Due to this knowledge novel applications become possible that provide services with proactive knowledge to users. The most serious problem of context prediction mechanisms lies in a basic property of prediction itself. A prediction is always a guess. Since erroneous predictions may cause the application to behave insufficiently,...
The ability to predict future contexts significantly expands the possibilities of context-aware computing applications. However, an incorrect prediction may also mislead the application and may result in inappropriate application behaviour. We study influences on the prediction accuracy and propose a novel approach to context prediction in ubiquitous computing environments. In our paper we introduce...
We study the impact of the context interpretation error on the context prediction accuracy. Benefits and drawbacks of current context prediction schemes are analysed and opposed to a contemporary alternative. We propose a novel context prediction scheme that has the potential to significantly improve the context prediction accuracy. The impact of the context interpretation error on the context prediction...
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