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W części teoretycznej pracy scharakteryzowano rozkład Poissona oraz nieparametryczny test zgodności chi-kwadrat Pearsona. Przedstawiono również metodę weryfikacji hipotez dotyczących zbieżności dowolnego typu danych stanowiących zmienną losową, w tym wyników pomiarów, z rozkładem Poissona. Praktyczna część pracy polegała na określeniu zbieżności ruchu telekomunikacyjnego generowanego w sieci transmisji...
We proposed the “Quasi-static approach” as a method that can analyze the stability of a telecommunication system experiencing retry traffic. This method considers human interaction with the system, and use the difference of timescale between humans and system. Our recent studies evaluated the stability when all traffic including retry traffic has the same holding-time distribution as calls in the...
In most articles dataflow in computer networks is described as a transfer function. Numerators, denominators and delay times give behaviors of these systems. Some systems show linear features, others have non-linear ones. All descriptions have some special results. Some of them present linear aspects of transfers, while other ones look for bottlenecks of the networks or prove stability of the systems...
DDoS attack is a major Internet security problem-DoS is that lots of clients simultaneously send service requests to certain server on the internet such that this server is too busy to provide normal services for others. Attackers using legitimate packets and often changing package information, so that traditional detection methods based on feature descriptions is difficult to detect it. This paper...
As multimedia real-time businesses with representative of video come into the network services, real-time performance of campus network has are influenced by similar traffic of video passing through without control. In this paper, by use of the forwarding characteristics of packet/frame switch, a strategy to reduce the self-similar traffic's impact on network performance is discussed, which is based...
Multiprotocol Label Switching (MPLS) is an Internet Engineering Task Force (IETF) specified framework that provides for the efficient designation, routing, forwarding and switching of traffic flows through the network. MPLS is a versatile solution to address the problems faced by present-day networks like speed, scalability, quality-of-service (QoS) management, and traffic engineering. MPLS carries...
In WDM networks, failures may occur in node or link and hence all the fibers which involves the failed link, also fails. In order to protect against the failures, protection and the restoration fault tolerance methods can be utilized. But both of the methods include several demerits. In this paper, we propose to develop a hybrid adaptive algorithm for fault tolerance in survivable WDM networks which...
In order to achieve the best performance of a Wireless Sensor Network (WSN), it is a must to provide a challengeable routing algorithm , which consumes less power and allows more data collection. In this paper we have considered a WSN with mobile sinks and it is considered that the router follows the basic location update algorithm with traffic awareness. We show the performances of a router under...
Unlike traditional routing schemes that route all traffic along a single path, multipath routing strategies split the traffic among several paths in order to ease congestion. It has been widely recognized that multipath routing can be fundamentally more efficient than the traditional approach of routing along single paths. aiming at the increasing network traffic and the deficity that the former Ant...
Monitoring large chunks of unused IP address space yields interesting observations and useful results. However, the volume and diversity of the collected data makes the extraction of information a challenging task. Additionally, the maintenance of the monitoring infrastructure is another demanding and time-consuming effort. To overcome these problems, we present several visualization techniques that...
Fourth Generation Networks will invariably adopt MIMO-OFDMA techniques, in order to cope with increased data rate demands and improved Quality of Service (QoS) requirements. OFDMA is a popular multiple access candidate, since it facilitates multi-user diversity by enabling two dimensional multiple access, in time and frequency domains. Random Beamforming enables exploitation of spatial multi-user...
This paper focuses on the performance evaluation of LTE uplink in presence of bursty data traffic. First, the performance of different power control (PC) strategies in different load conditions is evaluated. It is shown that the optimal PV policy depends on the load in the network and/or in the own cell. Simulation results demonstrate that in low load conditions applying no PC (or alternatively using...
This paper mostly concerned with the various packet size effect on performance of erasure correctable codes for cognitive radio. Among these types of codes we tried to simulate Raptor code to discover its suitability for assumed erasure channel in cognitive radio. The main target after supporting the functionality of coding-based cognitive radio would be finding the appropriate packet length that...
Small cell base stations (BSs) that form an overlay layer on the existing macrocell network offer tremendous potential in terms of satisfying high data rate traffic requirements and enabling breakthrough services. However; small cell deployments can pose negative energy-efficiency implications if not equipped with advanced power saving mechanisms. In this work, we address this issue and propose algorithms...
Opportunistic routing has gained much attention in recent years as a means of leveraging the broadcast nature of wireless medium. Most of the previous studies focused only on improving throughput, assuming that Best Effort traffic which is delay insensitive is delivered through opportunistic routing. However, when the delay sensitive traffic is involved, it is necessary to consider both the opportunistic...
One of main feature of next generation of mobile networks is an integration of existing cellular systems with other wireless access technologies. In order to realize a seamless vertical handover (inter-RAT handover) among these different access technologies, a multi-interfaced mobile station is expected to communicate simultaneously on various network interfaces (i.e. to be multihomed) to achieve...
The roll-out of UMTS/HSPA networks in 900MHz band offers the possibility to bring third generation and mobile broadband services to new areas with less base station sites and to improve the indoor coverage in the existing UMTS coverage areas. However, a necessary first step in order to take advantage of the mentioned benefits of UMTS/HSPA900 networks is a partial clearance of spectrum in the 900 MHz...
GSM networks consist of cells that can support mobile users. Due to this mobility, it is expected that the network model can be different than that of wired networks which do not support mobile users. In our study, using empirical data provided by a GSM operator, TURKCELL, we analyze the associated network model from the mobility perspective. We first show that the handover rate of a regular cell...
This work presents a traffic-based, mobility-aware clustering algorithm tailored for application scenarios typical of low data rate IEEE 802.15.4a networks and characterized by a hierarchical network organization. The proposed algorithm adapts to emerging traffic and mobility patterns in the network by selecting as cluster heads nodes that are the intended destinations for a large number of packets,...
The capacity and coverage area of a cell may vary due to changed environment, insertion or deletion of base stations, or malfunctioning base stations, and wrong parameter selection in the network planning phase. Suboptimal capacity and coverage area leads to the waste of network resources and the lower quality. Reacting on the changed situation manually is very expensive and time consuming. Therefore,...
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