Experimental Study of the Impact of WLAN Interference on IEEE 802.15.4 Body Area Networks ⋆

Abstract. As the number of wireless devices sharing the unlicensed 2.4 GHz ISM band increases, interference is becoming a problem of paramount importance. We experimentally investigate the effects of controlled 802.11b interference as well as realistic urban RF interference on packet delivery performance in IEEE 802.15.4 body area networks. Our multi-channel measurements, conducted with Tmote Sky sensor nodes, show that in the low-power regime external interference is typically the major cause for substantial packet loss. We report on the empirical correlation between 802.15.4 packet delivery performance and urban WLAN activity and explore 802.15.4 cross-channel quality correlation. Lastly, we examine trends in the noise floor as a potential trigger for channel hopping to detect and mitigate the effects of interference

Smart government as a key factor in the creation of a smart city

The essence of the smart city concept is to increase the quality of life in cities with an emphasis on digital technologies. This mainly concerns the participation in decision-making as a part of the smart government. The participation means opportunity for citizens to participate in the management of the city. This academic paper presents basic concepts of a smart city as well as specific ways how smart cities can increase the participation of their citizenry, especially with regard to social media. Based on a literature search it is obvious that the involvement of citizens strengthens democracy and the quality of the decision-making process.[IGA/FaME/2016/010

Wireless sensor networks for soil science

Abstract: Wireless sensor networks can revolutionize soil ecology by providing measurements at temporal and spatial granularities previously impossible. This paper presents our first steps towards fulfilling that goal by developing and deploying two experimental soil monitoring networks at urban forests in Baltimore, MD. The nodes of these networks periodically measure soil moisture and temperature and store the measurements in local memory. Raw measurements are incrementally retrieved by a sensor gateway and persistently stored in a database. The database also stores calibrated versions of the collected data. The measurement database is available to third-party applications through various Web Services interfaces. At a high level, the deployments were successful in exposing high level variations of soil factors. However, we have encounteredanumberof challenging technical problems: need for low-level programming at multiple levels, calibration across space and time, and sensor faults. These problems must be addressed before sensor networks can fulfill their potential as high-quality instruments that can be deployed by scientists withou

Implementation and analysis of Wireless Flexible Time-Triggered protocol

During the last few years, wireless low-power communications experienced an increasing coexistence and traction as a result of the higher demand posed by power constrained applications. On the other hand, this increasing wireless coexistence is a growing concern and Low-power wireless communication protocols have been shown to experience a significant timeliness and reliability degradation under certain interference profiles. Therefore, the support of real-time communications over license-free bands in open environments, encompassing multiple real-time stations with an unknown number of unconstrained stations, is a challenging task. Provided that this impairment has hindered their wide adoption in demanding real-time scenarios, the Wireless Flexible Time Triggered (WFTT) protocol has been recently proposed targeting applications with stringent timeliness requirements. This protocol works on the medium access determinism granted by the bandjacking technique in open environments, where different technologies may contend for the medium. Besides providing a deeper definition of the WFTT architecture and protocol operation, this paper presents a thorough analysis addressing its specifications, implementation feasibility and testbed based results. These provide strong evidence that the WFTT protocol is able to support real-time communications, even in environments affected by high levels of interference from neighboring contention-based communication technologies such as Wi-Fi