Properties of the Multiservice Erlang's Ideal Gradings, Journal of Telecommunications and Information Technology, 2016, nr 1

The design and optimization process of modern telecommunications networks is supported by a range of appropriate analytical models. A number of these models are based on the Erlang’s Ideal Grading (EIG) model, which is a particular case of non-full-availability groups. A possibility of the application of the EIG model results from the fact that telecommunications systems show properties and features distinctive to non-full-availability systems. No detailed studies that would decisively help determine appropriate conditions for the application of the EIG model for modeling of other non-full-availability groups, that would be models corresponding to real telecommunications systems, have been performed. Therefore, this article attempts to find an answer to the following question: what are the prerequisite conditions for the application of the EIG model and when the model can be reliably used

QoS Equalization in a W-CDMA Cell Supporting Calls of Innite or Finite Sources with Interference Cancelation, Journal of Telecommunications and Information Technology, 2014, nr 3

In this paper, a multirate loss model for the calculation of time and call congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell is considered. It utilizes the Bandwidth Reservation (BR) policy and supports calls generated by an innite or nite number of users. The BR policy achieves QoS equalization by equalizing congestion probabilities among calls of dierent service-classes. In the proposed models a multiple access interference is considered, and the notion of local blocking, user's activity and interference cancelation. Although the analysis of the proposed models reveals that the steady state probabilities do not have a product form solution, the authors show that the calculation of time and call congestion probabilities can be based on approximate but recursive formulas, whose accuracy is veried through simulation and found to be quite satisfactory

Risk-aware Urban Air Mobility Network Design with Overflow Redundancy

Urban Air Mobility (UAM), as envisioned by researchers and practitioners, will be achieved through the use of highly automated aircraft that operate and transport passengers and cargo at low altitudes within urban and suburban areas. To operate in complex urban environment, precise air traffic management, in particular the management of traffic overflows due to operational disruptions will be critical to ensuring system safety and efficiency. To this end, we propose a methodology for the design of UAM networks with reserve capacity, i.e., a design where alternative landing options and flight corridors are explicitly considered as a means of improving contingency management and reducing risk. Similar redundancy considerations are incorporated in the design of many critical infrastructures, yet remain unexploited in the air transportation literature. In our methodology, we first model how disruptions to a given on-demand UAM network might impact on the nominal traffic flow and how this flow might be re-accommodated on an extended network with reserve capacity. Then, through an optimization problem, we select the locations and capacities for the backup vertiports with the maximal expected throughput of the extended network over all possible disruption scenarios, while the throughput is the maximal amount of flights that the network can accommodate per unit of time. We show that we can obtain the solution for the corresponding bi-level and bi-linear optimization problem by solving a mixed-integer linear program. We demonstrate our methodology in the case study using networks from Milwaukee, Atlanta, and Dallas--Fort Worth metropolitan areas and show how the throughput and flexibility of the UAM networks with reserve capacity can outcompete those without.Comment: 43 pages, 10 figure

Journal of Telecommunications and Information Technology, 2014, nr 3

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