IEEE 802.15.4 is a new standard uniquely designed for low rate wireless personal area networks (LRWPANs). It targets low data rate, low power consumption and low cost wireless networking, and offers device level wireless connectivity. We develop an NS2 simulator for IEEE 802.15.4 and conduct several sets of experiments to study its various features, including: (1) beacon enabled mode and non-be...

The National Aeronautics and Space Administration Advanced Communications Technology Satellite (ACTS) propagation experiment was designed to obtain slant-path attenuation statistics for locations within the United States and Canada for use in the design of low-margin Ka-band satellite communication systems. Experimenters at seven different locations have collected propagation data for more than...

Fluorescence monitoring of endogenous microRNA (miRNA or miR) activity related to neuronal development using nano-sized materials provides crucial information on miRNA expression patterns in a noninvasive manner. In this study, we report a new method to monitor intracellular miRNA124a using quantum dot-based molecular beacon (R9-QD-miR124a beacon). The R9-QD-miR124a beacon was constructed using...

Denial of Service (DoS) attacks pose a fast-growing threat to network services in the Internet, but also corporate Intranets and public local area networks like Wi-Fi hotspots may be affected. Especially protocols that perform authentication and key exchange relying on expensive public key cryptography are likely to be preferred targets. A well-known countermeasure against resource depletion at...

Adaptive optics combined with visual psychophysics creates the potential to study the relationship between visual function and the retina at the cellular scale. This potential is hampered, however, by visual interference from the wavefront-sensing beacon used during correction. For example, we have previously shown that even a dim, visible beacon can alter stimulus perception (Hofer et al., 201...

Wireless sensor networks based on the IEEE 802.15.4 standard are able to achieve low-power transmissions in the low-rate and short-distance wireless personal area network (PAN). A cluster tree network consists of several clusters; each cluster has a coordinator, known as cluster coordinator, and several device nodes. In the cluster tree topology of IEEE 802.15.4, a PAN coordinator periodically ...

Motivated by station-keeping applications in various unmanned settings, this paper introduces a steering control law for a pair of agents operating in the vicinity of a fixed beacon in a three-dimensional environment. This feedback law is a modification of the previously studied three-dimensional constant bearing (CB) pursuit law, in the sense that it incorporates an additional term to allocate...

Traditionally, there have been few options for navigational aids for the blind and visually impaired (BVI) in large indoor spaces. Some recent indoor navigation systems allow users equipped with smartphones to interact with low cost Bluetoothbased beacons deployed strategically within the indoor space of interest to navigate their surroundings. A major challenge in deploying such beacon-based n...

Beacon node placement, node-to-node measurement, and target node positioning are the three key steps for a localization process. However, compared with the other two steps, beacon node placement still lacks a comprehensive, systematic study in research literatures. To fill this gap, we address the Beacon Node Placment (BNP) problem that deploys beacon nodes for minimal localization error in thi...

 A cluster tree network is a special case of a peer-to-peer network in which most devices are full function devices (FFDs). Any FFD may serves as a coordinator and implements synchronization services to other devices or other coordinators. However, if the coordinator nodes send periodic beacon frames at inappropriate time, the beacon transmission will be collide each other and prevent children...