Piotr Zwierzykowski

Uplink Blocking Probability Calculation for Cellular Systems with WCDMA Radio Interface, Finite Source Population and Differently Loaded Neighbouring Cells

This paper presents the uplink blocking probability calculation method in cellular systems with WCDMA radio interface, finite source population and differently loaded neighbouring cells. The method is based on the model of the full availability group with multi-rate traffic streams. A fixed point methodology has been used in the proposed method. The proposed scheme could be utilized for cost-effective radio resource management in 3G mobile networks and can be easily applied to network capacity calculations

Modelling of the WCDMA Interface in the UMTS Network with Soft Handoff Mechanism

The paper proposes an analytical approach to blocking probability calculation in the UMTS network carrying a mixture of multi-rate traffic, under the assumption that the part of resources of the interface is dedicated for servicing handoff traffic. In the proposed method, handoff connections are modeled on the basis of the fixed point methodology and dynamic reservation. The results of analytical calculation of the blocking probability in the group of cells carrying a mixture of different multi-rate traffic streams are compared with the results of the simulation experiments, which confirms a rather high accuracy of the method. The described calculation scheme is applicable for cost-effective resource management in 3G mobile networks and can be easily applied to network capacity calculations.

An Approximate Model of the WCDMA Interface Servicing a Mixture of Multi-rate Traffic Streams with Priorities

The paper presents an approximate method for blocking probability determination in the WCDMA interface of the UMTS network with priorities. In our considerations we use a new model of the full-availability group servicing multi-rate traffic with priorities. In the proposed model we assume that a new call with a higher priority can terminate connections already in service if they are characterized by a lower priority than a new call. The proposed scheme is applicable for cost-effective WCDMA resource management in 3G mobile networks and can be easily applied to network capacity calculations.

Dijkstra-based localized multicast routing in Wireless Sensor Networks

Limited resources in Wireless Sensor Networks (WSNs) are the key concern that needs to be given a careful consideration when studying virtually any aspect of a sensor network. Therefore, energy demands and radio bandwidth utilization should be addressed, especially in one-to-many communication. To define the problem, this article presents and categorizes the most common WSN multicast procedures depending on the way a target group is identified by the means of geographic position. It is evident that a need for centralized network-wide topology knowledge can jeopardize scarce energy resources of a sensor network. Thus, localized geographic multicast relies solely on locally available information about the position of current node, other nodes within the radio range and the location of destination group members. Greedy multicast routing procedures often transport messages along paths that may be far from being optimal. Therefore, Dijkstra-based Localized Energy-Efficient Multicast Algorithm (DLEMA) is introduced. DLEMA focuses on discovering energy shortest paths leading through nodes that provide maximum geographical advance towards desired destinations. The analysis of the simulation results confirms interesting characteristics of the proposed algorithm.

Analytical Model of Traffic Compression in the UMTS Network

The paper presents a new simple analytical method for a determination of the blocking probability in a full-availability group carrying a mixture of different multi-rate traffic classes with the compression property. The proposed model can be directly used for modelling of the Iub interface in the UMTS network servicing the Release 99 and HSDPA traffic classes. The described model can be applied for the validation of the efficiency of the Iub interface measured by the blocking probability and the average carried traffic for particular traffic classes.

Efficiency Analysis of Multicast Routing Algorithms in Large Networks

The paper presents the research results of multicast heuristic algorithms. The paper is an extension of previous publications presented in [14, 15] that discussed small network structures reflecting real Internet topology. It approaches basic methods of generating the Internet topology - Waxman method and the Barabasi-Albert method. A performance study of multicast trees constructed by the algorithms is carried out and analysed, also with the heuristic network generator - Inet.

Analytical model of ATM node with multicast switching

This paper presents a new analytical model of ATM node to which a mixture of different multi-rate traffic streams, including multicast traffic, is offered. The model allows one to calculate the blocking probability for calls of all traffic classes. An example of calculations of a network node with three outgoing directions is given. The results of the analytical calculation are compared with the results of simulation, and therefore, the validity of the assumption used is proved. The formulae derived in this paper can be used in the analysis of B-ISDN systems.

Modelling of virtual‐circuit switching nodes with multicast connections

This paper presents an approximate calculation methodology of the occupancy distribution and the blocking probability in a virtual circuit switching node with multi-rate unicast and multicast traffic streams. Particular traffic streams are generated by an infinite as well as by a finite population of traffic sources. The model enables calculations of any structure of the groups forming the outgoing directions of the node. Additionally, bandwidth reservation algorithms are also proposed in order to improve traffic characteristics of different traffic classes. The results of the analytical calculations have been compared with the simulation results of a switching node carrying multicast and unicast traffic streams. Copyright

Equalisation of Blocking Probability in Switching Systems with Limited Availability

Three reservation algorithms for the limited-availability system are proposed and compared in the paper. These algorithms can be used for call blocking equalisation in outgoing links of multiservice switching networks. Two approximate methods of equalised blocking probability calculation in the system with limited availability are proposed. Results of analytical calculations are compared with results of digital simulation of limited availability groups and switching networks with reservation. These researches have confirmed a great accuracy of the proposed calculation methods. The formulae derived by the authors can be useful for the analysis and design of ISDN and B-ISDN systems.

Performance of Fast Multicast Algorithms in Real Networks

Multicast heuristic algorithms are currently the field of interest for networks researchers. The optimization analysis of fast algorithms is performed using random and heuristic networks (graphs). This theoretical work approaches problem of constructing trees between the sender and group of receivers in real computer networks. The paper presents basic methods of generating the Internet topology on graph level -Waxman method and the Barabasi-Albert method. A performance study of multicast trees constructed by the algorithms is carried out and analysed, also with the heuristic network generator -Inet.