scholarly journals An Introduction to VoIP: End-to-End Elements and QoS Parameters

10.5772/13520 ◽  
2011 ◽  
Author(s):  
H. Toral-Cruz ◽  
J. Argaez-Xool ◽  
L. Estrada-Vargas ◽  
D. Torres-Rom
Keyword(s):  
Qos Parameters ◽  
End To End

Evaluating The Performance for DCF Protocol and EDCA Protocol

2015 ◽  
Vol 72 (5) ◽  
Author(s):  
Ahmed Abu-Khadrah ◽  
Zahriladha Zakaria ◽  
Mohdazlishah Othman
Keyword(s):  
Real Time ◽  
Packet Loss ◽  
Area Network ◽  
Distributed Coordination ◽  
Data Types ◽  
End To End Delay ◽  
Main Challenge ◽  
Qos Parameters ◽  
End To End ◽  
Coordination Function

Nowadays supporting quality of service (QOS) for real time application is the main challenge of the wireless area network. 802.11standards use distributed Coordination Function (DCF) protocol and Enhanced Distributed Channel Access (EDCA) protocol in the MAC layer. DCF protocol has only one queue for different data types, it deals with data depending on the arriving time. There is no priority to serve real time applications faster. However EDCA protocol has four queues and each queue works with specific data type. Voice, video, best effort and background are the different queues in the EDCA protocol. Different parameters and priorities are defined for each queue. The voice queue reserves the highest priority and serves its data first. In this paper QOS parameters are measured for both DCF and EDCA protocol by using OPNET simulation. The QOS parameters must reach the requirements to support QOS. The results show how QOS parameters do not reach the requirements when using DCF protocol. The values of the end to end delay and the packet loss percentage are 0.514second, 19.04% respectively. But, when using EDCA protocol the end to end delay becomes 0.0624 second and the percentage of the packet loss decreases until reach 0.00617%. So the QOS parameters achieve requirements with EDCA protocol and support QOS.

Network analysis on Skype end-to-end video quality

2015 ◽  
Vol 11 (1) ◽  
pp. 17-42 ◽  
Author(s):  
George Exarchakos ◽  
Luca Druda ◽  
Vlado Menkovski ◽  
Antonio Liotta
Keyword(s):  
Real Time ◽  
Video Streaming ◽  
Video Quality ◽  
Adaptive Streaming ◽  
Content Type ◽  
Adaptive Mechanisms ◽  
Qos Parameters ◽  
End To End ◽  
Motion Video

Purpose – This paper aims to argue on the efficiency of Quality of Service (QoS)-based adaptive streaming with regards to perceived quality Quality of Experience (QoE). Although QoS parameters are extensively used even by high-end adaptive streaming algorithms, achieved QoE fails to justify their use in real-time streaming videos with high motion. While subjective measurements of video quality are difficult to be applied at runtime, objective QoE assessment can be easier to automate. For end-to-end QoS optimization of live streaming of high-motion video, objective QoE is a more applicable approach. This paper contributes to the understanding of how specific QoS parameters affect objective QoE measurements on real-time high-motion video streaming. Design/methodology/approach – The paper approached the question through real-life and extensive experimentation using the Skype adaptive mechanisms. Two Skype terminals were connected through a QoS impairment box. A reference video was used as input to one Skype terminal and streamed on one direction. The impairment box was stressing the stream with different conditions. Received video was stored and compared against the reference video. Findings – After the experimental analysis, the paper concludes that adaptive mechanisms based on QoS-related heuristics fail to follow unexpected changes to stream requirements. High-motion videos are an example of this variability, which makes the perceived quality sensitive to jitter more than to packet loss. More specifically, Skype seems to use if-else heuristics to decide its behavior to QoS changes. The weaknesses to high-motion videos seem to lie on this rigidity. Research limitations/implications – Due to the testbed developed, the results may be different if experiments are run over networks with simultaneous streams and a variety of other traffic patterns. Finally, other streaming clients and algorithms would contribute to a more reliable generalization. Practical implications – The paper motivates video streaming engineers to emphasize their efforts toward QoE and end-to-end optimization. Originality/value – The paper identifies the need of a generic adaptive streaming algorithm able to accommodate a big range of video characteristics. The effect of QoS variability to high-motion video streaming helps in modeling and design.

scholarly journals Performance of a new bus assignment algorithm for an ATM switch fabric

2004 ◽  
Vol 2 (02) ◽  
Author(s):  
J. Garcí­a-Hernández ◽  
M. Ghanbari
Keyword(s):  
Atm Network ◽  
Atm Switch ◽  
Network Load ◽  
Qos Parameters ◽  
End To End ◽  
Small Increments ◽  
Atm Switches ◽  
Cell Delay ◽  
Delay Variation

The measurement of the quality of service in ATM* networks involves the activation of the ATM layer management OAM functions. Once an ATM connection is set up, in-service performance monitoring based on OAM cells can be used to measure and estimate the ATM layer QoS parameters. In-service measurement of ATM layer QoS parameters such as cell delay variation, cell transfer delay, cell loss ratio, etc., is necessary to verify on one hand, if the network is meeting the requested QoS and on the other hand, if the users are receiving their promised QoS. Congestion conditions in ATM switches may cause gradual deteriorations in the quality of virtual paths or virtual channel connections in an ATM network. QoS measurement using OAM cells can accurately measure the overall quality of monitored ATM layer QoS parameters in order to detect such deteriorations before the service quality has dropped bellow an acceptable level. Several factors such as network load, congestion, bottlenecks, and incremenTS in network load may affect the cell delay variation of video transmissions in an ATM network. In this work, several ATM layer QoS parameters have been measured on a VBR video source using OAM cells. The simulation resulTS obtained show that with low network loads, the contribution of each individual ATM switch to the local and to the end-to-end CDV is not significant. In the presence of a bottleneck switch, the CDV presented by this switch becomes the dominant one at both local and end-to-end sides. When the network load is between 0.5 and 0.6, small incremenTS in network load do not alter the buffer performance of the non-congested ATM switches, and low values of CDV can be obtained. In contrast, it was found that there is a critical load between 0.65 and 0.7 where small incremenTS in network load may force the CDV to grow abruptly.

Surgical management of extracranial carotid artery aneurysms

VASA ◽  
2016 ◽  
Vol 45 (3) ◽  
pp. 223-228 ◽  
Author(s):  
Jan Paweł Skóra ◽  
Jacek Kurcz ◽  
Krzysztof Korta ◽  
Przemysław Szyber ◽  
Tadeusz Andrzej Dorobisz ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Surgical Management ◽  
Minor Stroke ◽  
Stroke Rate ◽  
Extracranial Carotid Artery ◽  
Long Term Follow Up ◽  
End To End ◽  
Dacron Patch ◽  
Major Stroke

Abstract. Background: We present the methods and results of the surgical management of extracranial carotid artery aneurysms (ECCA). Postoperative complications including early and late neurological events were analysed. Correlation between reconstruction techniques and morphology of ECCA was assessed in this retrospective study. Patients and methods: In total, 32 reconstructions of ECCA were performed in 31 symptomatic patients with a mean age of 59.2 (range 33 - 84) years. The causes of ECCA were divided among atherosclerosis (n = 25; 78.1 %), previous carotid endarterectomy with Dacron patch (n = 4; 12.5 %), iatrogenic injury (n = 2; 6.3 %) and infection (n = 1; 3.1 %). In 23 cases, intervention consisted of carotid bypass. Aneurysmectomy with end-to-end suture was performed in 4 cases. Aneurysmal resection with patching was done in 2 cases and aneurysmorrhaphy without patching in another 2 cases. In 1 case, ligature of the internal carotid artery (ICA) was required. Results: Technical success defined as the preservation of ICA patency was achieved in 31 cases (96.9 %). There was one perioperative death due to major stroke (3.1 %). Two cases of minor stroke occurred in the 30-day observation period (6.3 %). Three patients had a transient hypoglossal nerve palsy that subsided spontaneously (9.4 %). At a mean long-term follow-up of 68 months, there were no major or minor ipsilateral strokes or surgery-related deaths reported. In all 30 surviving patients (96.9 %), long-term clinical outcomes were free from ipsilateral neurological symptoms. Conclusions: Open surgery is a relatively safe method in the therapy of ECCA. Surgical repair of ECCAs can be associated with an acceptable major stroke rate and moderate minor stroke rate. Complication-free long-term outcomes can be achieved in as many as 96.9 % of patients. Aneurysmectomy with end-to-end anastomosis or bypass surgery can be implemented during open repair of ECCA.

Reliability of the Mangled Extremity Severity Score in the Management of Peripheral Vascular Injuries in Children: A Retrospective Review

2020 ◽  
Author(s):  
Ahmed Mousa ◽  
Ossama M. Zakaria ◽  
Mai A. Elkalla ◽  
Lotfy A. Abdelsattar ◽  
Hamad Al-Game'a
Keyword(s):  
Severity Score ◽  
Vein Graft ◽  
Bypass Surgery ◽  
Age Groups ◽  
Vascular Injuries ◽  
Peripheral Vascular ◽  
Group Iii ◽  
Mangled Extremity ◽  
Group I ◽  
End To End

AbstractThis study was aimed to evaluate different management modalities for peripheral vascular trauma in children, with the aid of the Mangled Extremity Severity Score (MESS). A single-center retrospective analysis took place between 2010 and 2017 at University Hospitals, having emergencies and critical care centers. Different types of vascular repair were adopted by skillful vascular experts and highly trained pediatric surgeons. Patients were divided into three different age groups. Group I included those children between 5 and 10 years; group II involved pediatrics between 11 and 15 years; while children between 16 and 21 years participated in group III. We recruited 183 children with peripheral vascular injuries. They were 87% males and 13% females, with the mean age of 14.72 ± 04. Arteriorrhaphy was performed in 32%; end-to-end anastomosis and natural vein graft were adopted in 40.5 and 49%, respectively. On the other hand, 10.5% underwent bypass surgery. The age groups I and II are highly susceptible to penetrating trauma (p = 0.001), while patients with an extreme age (i.e., group III) are more susceptible to blunt injury (p = 0.001). The MESS has a significant correlation to both age groups I and II (p = 0.001). Vein patch angioplasty and end-to-end primary repair should be adopted as the main treatment options for the repair of extremity vascular injuries in children. Moreover, other treatment modalities, such as repair with autologous vein graft/bypass surgery, may be adopted whenever possible. They are cost-effective, reliable, and simple techniques with fewer postoperative complication, especially in poor/limited resources.

WS-Security on PRODML

2014 ◽  
Vol 1 (1) ◽  
pp. 9-34
Author(s):  
Bobby Suryajaya
Keyword(s):  
Web Services ◽  
Digital Signature ◽  
Data Transfer ◽  
Web Services Security ◽  
Soap Message ◽  
Simulation Results ◽  
End To End

SKK Migas plans to apply end-to-end security based on Web Services Security (WS-Security) for Sistem Operasi Terpadu (SOT). However, there are no prototype or simulation results that can support the plan that has already been communicated to many parties. This paper proposes an experiment that performs PRODML data transfer using WS-Security by altering the WSDL to include encryption and digital signature. The experiment utilizes SoapUI, and successfully loaded PRODML WSDL that had been altered with WSP-Policy based on X.509 to transfer a SOAP message.

Mit MindSphere die digitale Transformation vorantreiben

Controlling ◽  
2019 ◽  
Vol 31 (6) ◽  
pp. 63-65
Author(s):  
Carsten Speckmann ◽  
Péter Horváth
Keyword(s):  
Digitale Transformation ◽  
Internet Der Dinge ◽  
End To End

MindSphere ist das cloudbasierte, offene IoT-Betriebssystem von Siemens. Es verbindet Produkte, Anlagen, Systeme und Maschinen und ermöglicht es so, die Fülle von Daten aus dem Internet der Dinge (IoT) mit umfangreichen Analysen zu nutzen. Als eine sichere, skalierbare End-to-End-Lösung für die Industrie sorgt MindSphere für die Konnektivität von Anlagen und liefert somit handlungsrelevante Geschäftserkenntnisse, die zur Steigerung der Produktivität und Effizienz im gesamten Unternehmen nutzbar gemacht werden können. MindSphere ist weltweit verfügbar.

End-to-End Redundancy and Maintenance Condition Design for Nationwide Optical Transport Network

2018 ◽  
Vol E101.B (11) ◽  
pp. 2267-2276 ◽  
Author(s):  
Yoshihiko UEMATSU ◽  
Shohei KAMAMURA ◽  
Hiroshi YAMAMOTO ◽  
Aki FUKUDA ◽  
Rie HAYASHI
Keyword(s):  
Transport Network ◽  
Optical Transport Network ◽  
End To End ◽  
Optical Transport
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