The Oracle Problem When Testing from MSCs

Message Sequence Charts (MSCs) form a popular language in which scenario-based specifications and models can be written. There has been significant interest in automating aspects of testing from MSCs. This paper concerns the Oracle Problem, in which we have an observation made in testing and wish to know whether this is consistent with the specification. We assume that there is an MSC specification and consider the case where we have entirely independent local testers (local observability) and where the observations of the local testers are logged and brought together (tester observability). It transpires that under local observability the Oracle Problem can be solved in low-order polynomial time if we use sequencing, loops and choices but becomes NP-complete if we also allow parallel components; if we place a bound on the number of parallel components then it again can be solved in polynomial time. For tester observability, the problem is NP-complete when we have either loops or choices. However, it can be solved in low-order polynomial time if we have only one loop, no choices, and no parallel components. If we allow parallel components then the Oracle Problem is NP-complete for tester observability even if we restrict to the case where there are at most two processes

Investigating the adoption and use of smartphones in the UK : a silver-surfers perspective

Copyright and all rights therein are retained by the authors. All persons copying this information are expected to adhere to the terms and conditions invoked by each author's copyright. These works may not be re-posted without the explicit permission of the copyright holdersSmart phones are innovations that currently provide immense benefits and convenience to users in society. However, not all members of society are accepting and using smart phones; more specifically, for this research study silver-surfers or older adults (50+) are a demographic group displaying such an attitude. Currently, there is minimal knowledge of the reasons for older adults adopting and using smartphones. Bearing this in mind, this research study aims to investigate the adoption and usage behaviours of silver-surfers. For this purpose, the conceptual framework applied to this research draws factors from the following theories: Unified Theory of Acceptance and Use of Technology (UTAUT), the Diffusion of Innovations theory (DoI), and TAM3 (Technology Acceptance Model). From the online survey of 204 completed replies it was found that observability, compatibility, social influence, facilitating conditions, effort expectancy and enjoyment are important to the adoption and use of smartphones within silver-surfers. The contributions of this research are an identification and understanding of the factors that encourage or inhibit smartphone use within the older adult population. Second, this research can inform the design of computing devices and applications used for silver-surfers. Finally, this research can enlighten policy makers when forming decisions that encourage adoption and use of smartphones among silver surfersFinal Published versio

Observability of Path Loss Parameters in WLAN-Based Simultaneous Localization and Mapping

Indoor positioning by means of received signal strengths has been gathering much interest since the massive presence of wireless local area networks (WLANs) in buildings. Theoretical approaches rely on the perfect knowledge of the APs' positions and propagation conditions; since this is unrealistic in real world, we estimate such knowledge as well as the building map from data by applying Simultaneous Localization and Mapping (SLAM). In this paper we address the joint estimation of the path loss parameters, namely the transmitted power and the path loss exponent, this latter being usually approximated in the literature by the free space value. We provide examples that show the relevance of estimating both parameters and analyze observability issues from the point of view of estimation theory. The integration of the parameter estimation in a WLAN based SLAM algorithm - WiSLAM - has been carried out and the results are discussed

What Can Wireless Cellular Technologies Do about the Upcoming Smart Metering Traffic?

The introduction of smart electricity meters with cellular radio interface puts an additional load on the wireless cellular networks. Currently, these meters are designed for low duty cycle billing and occasional system check, which generates a low-rate sporadic traffic. As the number of distributed energy resources increases, the household power will become more variable and thus unpredictable from the viewpoint of the Distribution System Operator (DSO). It is therefore expected, in the near future, to have an increased number of Wide Area Measurement System (WAMS) devices with Phasor Measurement Unit (PMU)-like capabilities in the distribution grid, thus allowing the utilities to monitor the low voltage grid quality while providing information required for tighter grid control. From a communication standpoint, the traffic profile will change drastically towards higher data volumes and higher rates per device. In this paper, we characterize the current traffic generated by smart electricity meters and supplement it with the potential traffic requirements brought by introducing enhanced Smart Meters, i.e., meters with PMU-like capabilities. Our study shows how GSM/GPRS and LTE cellular system performance behaves with the current and next generation smart meters traffic, where it is clearly seen that the PMU data will seriously challenge these wireless systems. We conclude by highlighting the possible solutions for upgrading the cellular standards, in order to cope with the upcoming smart metering traffic.Comment: Submitted; change: corrected location of eSM box in Fig. 1; May 22, 2015: Major revision after review; v4: revised, accepted for publicatio