scholarly journals Analisis Kualitas VoIP pada SCTP Menggunakan ECN dan AQM

2015 ◽  
Vol 9 (2) ◽  
pp. 121
Author(s):  
La Surimi ◽  
Reza Pulungan
Keyword(s):  
Congestion Control ◽  
Real Time ◽  
Control Mechanism ◽  
Data Transfer ◽  
Reliable Data ◽  
Network Simulator ◽  
Independent Replication ◽  
Congestion Control Mechanism ◽  
Replication Technique

AbstrakVoIP merupakan aplikasi real time yang kualitasnya sangat tergantung pada delay dan jitter, yang mana hal ini sulit dipenuhi oleh protokol yang bersifat reliable dan memiliki congestion control seperti TCP. Di sisi lain penggunaan UDP yang tidak memiliki congestion control menyebabkan peluang terjadinya congestion pada jaringan sangat besar. Penggunaan SCTP sebagai protokol alternatif juga belum mampu mengakomodasi kekurangan TCP dan UDP. Beberapa hasil penelitian menunjukkan perlu adanya perbaikan ataupun modifikasi pada mekanisme congestion control yang dimiliki oleh SCTP. Penggunaan mekanisme ECN dan AQM  pada beberapa penelitian menunjukkan bahwa kedua mekanisme ini dapat menurunkan delay dan jitter. Penelitian ini melakukan pengujian terhadap kualitas VoIP di atas SCTP yang menggunakan ECN dan AVQ pada network simulator NS2. Hasil simulasi menunjukkan bahwa penggunaan mekanisme ECN dan AVQ pada protokol SCTP menghasilkan kualitas VoIP yang lebih baik pada kondisi jaringan yang tidak ideal (high Latency low Bandwidth dan low Latency low Bandwidth dari pada penggunaan protokol SCTP tanpa menggunakan mekanisme ECN dan AVQ. Penelitian ini juga melakukan perbandingan nilai MOS panggilan VoIP SCTP yang menggunakan ECN dan AVQ dengan nilai MOS panggilan VoIP yang menggunakan protokol TCP dan UDP. Hasilnya SCTP dengan ECN dan AVQ mengungguli TCP namun belum dapat mengungguli UDP. Kata kunci— VoIP, SCTP, ECN, AQM,AVQ. AbstractVoIP is the real time applications that are highly dependent on the quality of  delay and jitter, which it is difficult to be met by protocol that has reliable data transfer feature and  congestion control such as TCP. On the other hand the use of UDP that has no congestion control make chance of causing congestion in the network is very large. The use of SCTP as an alternative protocol was also not able to accommodate the weaknesses of TCP and UDP. Some research shows that repairs or modifications to the SCTP congestion control mechanism is needed.The Use of ECN and AQM in some studies show that these two mechanisms can reduce delay and jitter. This study tested the quality of VoIP over SCTP with ECN and AVQ, in NS2. Simulations carried out by independent replication technique, and the results showed that ECN and AVQ can increase the value of MOS VoIP calls significantly in non ideal network scenarios. This study also did comparison of SCTP MOS that uses ECN and AVQ with MOS values VoIP using TCP and UDP. The result showed that SCTP with ECN and AVQ outperform TCP but can not surpass UDP yet. Keywords— VoIP, SCTP, ECN, AQM,AVQ. 

A Dynamic Approach to Estimate Receiving Bandwidth for WebRTC

2016 ◽  
Vol 7 (3) ◽  
pp. 17-33
Author(s):  
Razib Iqbal ◽  
Shervin Shirmohammadi ◽  
Rasha Atwah
Keyword(s):  
Congestion Control ◽  
Real Time ◽  
Control Mechanism ◽  
Task Force ◽  
Round Trip Time ◽  
Round Trip ◽  
Dynamic Approach ◽  
Trip Time ◽  
Proposed Model ◽  
Congestion Control Mechanism

Web Real-Time Communication (WebRTC), drafted by the World Wide Web Consortium (W3C) and Internet Engineering Task Force (IETF), enables direct browser-to-browser real-time communication. As its congestion control mechanism, WebRTC uses the Google Congestion Control (GCC) algorithm. But using GCC will limit WebRTC's performance in cases of overusing due to using a fixed decreasing factor, known as alpha (a). In this paper, the authors propose a dynamic alpha model to reduce the receiving bandwidth estimate during overuse as indicated by the overuse detector. Using their proposed model, the receiver can more efficiently estimate its receiving rate in case of overuse. They implemented their model over both unconstrained and constrained networks. Experimental results show noticeable improvements in terms of higher incoming rate, lower Round-Trip Time, and lower packet loss compared to the fixed alpha model.

Shrew Attack on Internet Congestion Control Protocol in Control Engineering

2013 ◽  
Vol 648 ◽  
pp. 277-280
Author(s):  
Jian Hong Ma ◽  
Li Xia Ji
Keyword(s):  
Congestion Control ◽  
High Efficiency ◽  
Control Mechanism ◽  
Denial Of Service ◽  
Basic Mechanism ◽  
Network Simulator ◽  
Attack Model ◽  
Internet Congestion Control ◽  
Internet Congestion ◽  
Congestion Control Mechanism

Low-rate Denial of Service(LDoS) attacks with their hidden,high efficiency features can significantly degrade service performance of large number of connection-oriented services,or even worse,thoroughly deny the services.Shrew attack is a typical LDoS attack.Firstly we studied the basic mechanism of the attack and congestion control.The source of adaptive congestion control mechanism in the security vulnerability was revealed according to the different levels of the intrinsic link between Internet congestion control at TCP layer and IP layer.Secondly,using the Network simulator NS2 software package,we set up attack model to simulate a large number of attack experiments with various congestion control mechanism and algorithms.Finally we draw the conclusions that continuous Shrew attack makes services nearly crash,while congestion control algorithms taking into account of fairness,such as Stochastic Fairness Queuing (SFQ) and Deficit Round Robin (DRR),can effectively suppress such kind of attack.

Downlink Congestion Control for TD-SCDMA Trunking System

2011 ◽  
Vol 130-134 ◽  
pp. 3247-3250
Author(s):  
Ting Jian Zhang ◽  
Mei Juan Chen ◽  
Shi Xiang Shao
Keyword(s):  
Congestion Control ◽  
Control Mechanism ◽  
Mode Selection ◽  
System Level ◽  
User Mobility ◽  
System Level Simulation ◽  
Imperfect Power Control ◽  
Congestion Control Mechanism ◽  
And Performance

In TD-SCDMA trunking system, imperfect power control and user mobility are disadvantages for the capacity and performance of the system. In order to meet the requested Quality of Service (QoS) of group users, in this paper, we introduce a congestion control mechanism in downlink for TD-SCDMA trunking system. The mechanism is based on Adaptive Multi-Rate (AMR) mode selection and interrupt connections of users, analyzed in detail and verified by using MATLAB to structure a dynamic system level simulation platform. The simulation results reveal that system performance can be significantly improved.

scholarly journals A QoS-Oriented Congestion Control Mechanism for Satellite Networks

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Heyu Liu ◽  
Fuchun Sun
Keyword(s):  
Congestion Control ◽  
Data Flow ◽  
Control Mechanism ◽  
Satellite Networks ◽  
Satellite Network ◽  
Control Mechanisms ◽  
Network Congestion ◽  
Backbone Networks ◽  
Congestion Control Mechanism

The sharply increasing amount of data, which are transferred by the satellite network, requires the satellite network to provide quality-of-service (QoS). However, the upsurge in the data flow leads to the network congestion, impeding its ability to offer QoS. Congestion control mechanisms, deployed in the ground networks, have been thoroughly studied. But those deployed in the satellite networks have not been studied yet. As satellite networks are now important supplements to the ground backbone networks, this paper carefully analyzes the current challenges of developing the QoS-oriented congestion control mechanism for satellite networks. On this basis, a consequent mechanism QMCC (QoS-oriented mechanism of congestion control for satellite networks) is described in detail. Under that QMCC, the source nodes utilize an equation to compute the sending rate for each data flow; meanwhile, the intermediate nodes keep detecting real-time package-loss rates for timely adjustments. Simulation results indicate QMCC can provide superior congestion control performance, and raise network throughputs without reducing the QoS effects.

scholarly journals A novel congestion control mechanism for multicast real-time connections

1999 ◽  
Vol 22 (1) ◽  
pp. 56-72 ◽  
Author(s):  
Jau-Hsiung Huang ◽  
Chun-Chuan Yang ◽  
Nai-Cheng Fang
Keyword(s):  
Congestion Control ◽  
Real Time ◽  
Control Mechanism ◽  
Congestion Control Mechanism
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