Bozydar Dubalski

Bio: Bozydar Dubalski is an academic researcher from University of Technology and Life Sciences in Bydgoszcz. The author has contributed to research in topics: Chordal graph & Degree (graph theory). The author has an hindex of 9, co-authored 28 publications receiving 190 citations.

Assessing Measurements of QoS for Global Cloud Computing Services

Abstract: Many global distributed cloud computing applications and services running over the Internet, between globally dispersed clients and servers, will require certain levels of Quality of Service (QoS) in order to deliver and give a sufficiently smooth user experience. This would be essential for real-time streaming multimedia applications like online gaming and watching movies on a pay as you use basis hosted in a cloud computing environment. However, guaranteeing or even predicting QoS in global and diverse networks supporting complex hosting of application services is a very challenging issue that needs a stepwise refinement approach to be solved as the technology of cloud computing matures. In this paper, we investigate if latency in terms of simple Ping measurements can be used as an indicator for other QoS parameters such as jitter and throughput. The experiments were carried out on a global scale, between servers placed in universities in Denmark, Poland, Brazil and Malaysia. The results show some correlation between latency and throughput, and between latency and jitter, even though the results are not completely consistent. As a side result, we were able to monitor the changes in QoS parameters during a number of 24-hour periods. This is also a first step towards defining QoS parameters to be included in Service Level Agreements for cloud computing in the foreseeable future.

Energy Greedy Protocol Suite for Smart Grid Communication Systems Based on Short Range Devices

Abstract: In this paper, we present new communication protocol, named energy greedy quasi-flooding protocol. This protocol is independent from a communication media types and is mainly intended for PLC, UHF wireless and even IrDA transmission techniques. Presented solutions can be applied to EMSs based on the inexpensive SRDs, they are also suite for smart grid technologies based on hybrid networks e. g. PLC together with the wireless.

Comparison of modified chordal rings fourth degree to chordal rings sixth degree

Abstract: In this paper the comparison of modified chordal rings fourth nodal degree to sixth nodal degree has been given. In the first part of the paper analysis of chordal rings of sixth nodal degree has been presented. In the second part of the paper the comparison of the basic graphs parameters, diameter and average path length has been shown.

Analysis of Degree 5 Chordal Rings for Network Topologies

Abstract: This paper presents an analysis of degree 5 chordal rings, from a network topology point of view. The chordal rings are mainly evaluated with respect to average distance and diameter. We derive approximation expressions for the related ideal graphs, and show that these matches the real chordal rings fairly well. Moreover, the results are compared to that of a reference graph which presents a lower bound for average distance and diameter among all regular graphs of degree 5. It turns out that this reference graph has significantly lower distances than the degree 5 chordal rings. Based on that, we suggest that future research could deal with either finding degree 5 topologies with average distance and diameter closer to these of the reference graph, or to develop more realistic bounds than those presented by these reference graphs.

Toward cloud computing QoS architecture: analysis of cloud systems and cloud services

Abstract: Cloud can be defined as a new computing paradigm that provides scalable, on-demand, and virtualized resources for users. In this style of computing, users can access a shared pool of computing resources which are provisioned with minimal management efforts of users. Yet there are some obstacles and concerns about the use of clouds. Guaranteeing quality of service U+0028 QoS U+0029 by service providers can be regarded as one of the main concerns for companies tending to use it. Service provisioning in clouds is based on service level agreements representing a contract negotiated between users and providers. According to this contract, if a provider cannot satisfy its agreed application requirements, it should pay penalties as compensation. In this paper, we intend to carry out a comprehensive survey on the models proposed in literature with respect to the implementation principles to address the QoS guarantee issue.

Interaction of Retransmission, Blacklisting, and Routing Metrics for Reliability in Sensor Network Routing

Abstract: Unpredictable and heterogeneous links in a wireless sensor network require techniques to avoid low delivery rate and high delivery cost. Three commonly used techniques to help discover high quality paths include (1) link-layer retransmission, (2) blacklisting bad links, and (3) end-to-end routing metrics. Using simulation and testbed experiments, we present the rst systematic exploration of the tradeoffs of combinations of these approaches, quantifying the effects of each of these three techniques. We identify several key results: One is that per-hop retransmissions (ARQ) is a necessary addition to any other mechanism if reliable data delivery is a goal. Additional interactions between the services are more subtle. First, in a multihop network, either blacklisting or reliability metrics like ETX can provide consistent high-reliability paths when added to ARQ. Second, at higher deployment densities, blacklisting has a lower routing overhead than ETX. But at lower densities, blacklisting becomes less stable as the network partitions. These results are consistent across both simulation and testbed experiments. We conclude that ETX with retransmissions is the best choice in general, but that blacklisting may be worth considering at higher densities, either with or without ETX.

Management of Service Level Agreements for Cloud Services in IoT: A Systematic Mapping Study

Abstract: Cloud computing and Internet of Things (IoT) are computing technologies that provide services to consumers and businesses, allowing organizations to become more agile and flexible. Therefore, ensuring quality of service (QoS) through service-level agreements (SLAs) for such cloud-based services is crucial for both the service providers and service consumers. As SLAs are critical for cloud deployments and wider adoption of cloud services, the management of SLAs in cloud and IoT has thus become an important and essential aspect. This paper investigates the existing research on the management of SLAs in IoT applications that are based on cloud services. For this purpose, a systematic mapping study (a well-defined method) is conducted to identify the published research results that are relevant to SLAs. This paper identifies 328 primary studies and categorizes them into seven main technical classifications: SLA management, SLA definition, SLA modeling, SLA negotiation, SLA monitoring, SLA violation and trustworthiness, and SLA evolution. This paper also summarizes the research types, research contributions, and demographic information in these studies. The evaluation of the results shows that most of the approaches for managing SLAs are applied in academic or controlled experiments with limited industrial settings rather than in real industrial environments. Many studies focus on proposal models and methods to manage SLAs, and there is a lack of focus on the evolution perspective and a lack of adequate tool support to facilitate practitioners in their SLA management activities. Moreover, the scarce number of studies focusing on concrete metrics for qualitative or quantitative assessment of QoS in SLAs urges the need for in-depth research on metrics definition and measurements for SLAs.

How to Monitor QoS in Cloud Infrastructures: The QoSMONaaS Approach.

Abstract: Cloud computing provides a new paradigm to enable on-demand delivery of computing resources such as infrastructure, platforms and software as utilities to customers. When moving applications and/or data in the cloud, numerous challenges exist in leveraging the full potential that cloud computing promises. In this paper we address the challenging issue of QoS monitoring in a cloud environment. The availability of a dependable i.e., reliable and timely QoS monitoring facility is key for the real take up of cloud computing, since - by allowing organisations to receive the full value of cloud computing services - it would increase the level of trust they would place in this emerging technology. In this paper, we present a dependable QoS monitoring facility which relies on the 'as a service' paradigm, and can thus be made available to virtually all cloud users in a seamless way. Such a facility is called QoSMONaaS, which stands for 'quality of service monitoring as a service'. Details are given about the internal design and current implementation of the proposed facility.