Entity

Time filter

Source Type

Ipswich, United Kingdom

Moscholios I.D.,University of Peloponnese | Katsiva M.A.,University of Peloponnese | Kallos G.A.,BT Technology | Vassilakis V.G.,University of Surrey | Logothetis M.D.,University of Patras
2014 9th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2014 | Year: 2014

In this paper, we consider a multirate teletraffic loss model for the calculation of congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell that utilizes the Bandwidth Reservation (BR) policy and supports calls generated by a finite number of users. The BR policy is used particularly to equalize congestion probabilities among calls of different service-classes. In the proposed model we consider multiple access interference, the notion of local blocking, user's activity and interference cancellation. We show that the calculation of congestion probabilities is based on approximate but recursive formulas, whose accuracy is verified through simulation and found to be quite satisfactory. © 2014 IEEE. Source


Moscholios I.D.,University of Peloponnese | Vabilakis V.G.,University of Cambridge | Kallos G.A.,BT Technology | Logothetis M.D.,University of Patras
Proceedings of the 13th International Conference on Telecommunications, ConTEL 2015 | Year: 2015

CDMA-based technologies deserve abiduous analysis and evaluation. We study the performance, at call-level, of a CDMA cell with interference cancellation capabilities, while abuming that the cell accommodates different service-clabes of batched Poibon arriving calls. The partial batch blocking discipline is applied for Call Admibion Control (CAC). To guarantee certain Quality of Service (QoS) for each service-clab, the Bandwidth Reservation (BR) policy is incorporated in the CAC; i.e., a fraction of system resources is reserved for highspeed service-clabes. We propose a new multirate lob model for the calculation of time and call congestion probabilities. The notion of local (soft) and hard blocking, users activity, interference cancellation, as well as the BR policy, are incorporated in the model. Although the steady state probabilities of the system do not have a product form solution, time and call congestion probabilities can be efficiently determined via approximate but recursive formulas. Simulation verified the high accuracy of the new formulas. We also show the consistency of the proposed model in respect of its parameters, while comparison of the proposed model with that of Poibon input shows its necebity. © 2015 IEEE. Source


Moscholios I.D.,University of Peloponnese | Kallos G.A.,BT Technology | Katsiva M.A.,University of Peloponnese | Vassilakis V.G.,University of Surrey | Logothetis M.D.,University of Patras
Journal of Telecommunications and Information Technology | Year: 2014

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 infinite or finite number of users. The BR policy achieves QoS equalization by equalizing congestion probabilities among calls of different 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 verified through simulation and found to be quite satisfactory. Source


Moscholios I.D.,University of Peloponnese | Kallos G.A.,BT Technology | Vassilakis V.G.,University of Surrey | Logothetis M.D.,University of Patras
Wireless Personal Communications | Year: 2014

We propose a new multirate teletraffic loss model for the calculation of time and call congestion probabilities in CDMA-based networks that accommodate calls of different service-classes. The call arrival process follows a batched Poisson process, which is more “peaked” and “bursty” than the ordinary Poisson process. The call-admission-control policy is based on the partial batch blocking discipline. This policy accepts a part of the batch (one or more calls) and discards the rest, if the available resources are not enough to accept the whole batch. The proposed model takes into account multiple access interference, both the notion of local (soft) and hard blocking, the user’s activity, as well as interference cancellation. Although the analysis of the model does not lead to a product form solution of the steady state probabilities, we show that the call-level performance metrics, time and call congestion probabilities can be efficiently calculated based on approximate but recursive formulas. The accuracy of the proposed formulas are verified through simulation and found to be quite satisfactory. Comparison of the proposed model with that of Poisson input shows the necessity of the new model. We also show the consistency of the new model over changes of its parameters. © 2014, Springer Science+Business Media New York. Source


Arshad K.,University of Greenwich | Mackenzie R.,BT Technology | Celentano U.,University of Oulu | Drozdy A.,Budapest University of Technology and Economics | And 5 more authors.
IEEE Communications Magazine | Year: 2014

Cognitive radio technology is a key enabler to reuse a finite, scarce, and expensive resource: the radio spectrum. Guaranteeing required levels of QoS to cognitive users and ensuring necessary protection to incumbent users are the two main challenges in opportunistic spectrum access. This article identifies the main requirements and challenges for QoS support in cognitive radio networks. A framework for a twofold cognitive manager is presented; one part managing spectrum availability on longer timescales and the other handling resource management on shorter timescales. This article gives particular focus to the functionalities of the latter cognitive manager related to resource management. Finally, we present a few key scenarios and describe how QoS can be managed with the proposed approach without disturbing the communications of incumbent users. © 2014 IEEE. Source

Discover hidden collaborations