Search

In this paper, we present an analytical framework for dynamic priority queueing of handover calls in wireless networks. The framework employs a queueing discipline with two classes of priority for handover calls. Two queues, first priority and second priority, are employed for the two priority classes of handover calls. The priority of queued handover calls is not based only on the received signal strength, but also on the remaining time in the overlap region between two cells. We also incorporate a priority transition between handover calls in the queue; specifically, a second-priority handover call in the second-priority queue, based on certain criteria, can become a first-priority handover call and join the first-priority handover queue. In addition, the event that a handover call could finish its call while waiting in the queue is taken into account in the analysis. This event was not taken into consideration in previous related studies and, as a result, these previous studies overestimate handover failure probability. Our results also show that the predictions of the analytical framework developed in this paper are in very good agreement with simulation results. The developed analytical framework is comprehensive and can also cope with several priority schemes proposed by other researchers in the literature. For example, it is shown that, under certain conditions, the proposed framework converges to first-in-first-out queueing of handover calls. One can easily modify the proposed framework to incorporate priority schemes that use guard channels for handover calls. It is also shown that one could potentially use the framework developed in this paper in integrated voice/data networks, as well as for handover between different network types. The proposed analytical framework is anticipated to be a very useful tool in evaluating performance of present and future wireless networks employing dynamic priority queueing for handovers and ... [ABSTRACT FROM AUTHOR]

This paper presents a novel technique for analyzing the mode content excited by antennas placed in multimode waveguides. The technique is based on measuring the frequency response between the two antennas coupled into a waveguide and using that information to extract the mode content generated by the transmitting antenna. The technique is applicable to cases in which the mode amplitudes are approximately constant over the frequency range of interest. This method is valuable for determining the mode mix generated by arbitrary transmitting antennas in a multimode waveguide propagation environment. An example of such an environment is heating, ventilation, and air-conditioning (HVAC) ducts used for indoor communications, where an important antenna characteristic is the mode sensitivity (analogous to the antenna directive gain in free space). We validate our technique with the example of a monopole probe antenna coupled into a multimode cylindrical HVAC duct. Index Terms—Antennas; indoor radio communication; microwave measurements; multimode waveguides. [ABSTRACT FROM AUTHOR]

Heating, ventilation, and air conditioning (HVAC) ducts in buildings behave as multimode waveguides when excited at radio frequencies and thus, can be used to distribute radio signals. The channel properties of the ducts are different from the properties of a usual indoor propagation channel. In this paper, we describe physical mechanisms which affect the HVAC channel impulse response and analyze their influence on the delay spread. Those mechanisms include antenna coupling, attenuation, and three types of dispersion: intramodal, intermodal, and multipath. We analyze each type separately and explore the behavior of the delay spread as a function of distance in straight ducts. Experimental channel measurements taken on real ducts confirm the validity of our model. [ABSTRACT FROM AUTHOR]

Heating, ventilation, and air conditioning (HVAC) ducts in buildings are typically hollow metal pipes which can be used as waveguides to carry signals and provide the network access to offices. Knowledge of channel properties is crucial to designing such a communication system. This paper presents a propagation model for a straight HVAC duct terminated at both ends. At high frequencies this duct behaves as a multimode waveguide with a transmitting antenna coupling in and a receiving antenna coupling out. We derive a simple analytical expression for the frequency response of this channel using conventional techniques. Experimental data taken on real circular ducts excited by monopole probe antennas confirm theoretical results. This model represents an initial step toward the development of a tool for planning a wireless distribution system using building HVAC ducts. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editors talk about topics within the issue on the practical applications of the Internet of Things (IoT) in 5th generation (5G) mobile networks, including theory, industrial applications and opportunities for business.