Performance Analysis of TFRC and UDP over Mobile-IP Network with Competing Flows

This study aimed to conduct a performance analysis of TFRC and UDP over mobile-IP network with competing flows that enables to investigate three major performance metrics such as jitter, throughput, packet loss and packet delay. Two different transport layer protocols have been used in this analysis. As mobility has been the core issue of computing of 21st century, this research aims to contribute to this phenomenon by implementing performance analysis in mobile IP network, where mobile devices (nodes) are moved from access points to access points (AP) in order to exemplify the suitability of TFRC and UDP in wireless networking. Moreover to collect data about crucial performance metrics features. The experiment has been conducted by Network Simulation (NS-2)

On the quality of VoIP with DCCP for satellite communications

We present experimental results for the performance of selected voice codecs using DCCP with CCID4 congestion control over a satellite link. We evaluate the performance of both constant and variable data rate speech codecs for a number of simultaneous calls using the ITU E-model. We analyse the sources of packet losses and additionally analyse the effect of jitter which is one of the crucial parameters contributing to VoIP quality and has, to the best of our knowledge, not been considered previously in the published DCCP performance results. We propose modifications to the CCID4 algorithm and demonstrate how these improve the VoIP performance, without the need for additional link information other than what is already monitored by CCID4. We also demonstrate the fairness of the proposed modifications to other flows. Although the recently adopted changes to TFRC specification alleviate some of the performance issues for VoIP on satellite links, we argue that the characteristics of commercial satellite links necessitate consideration of further improvements. We identify the additional benefit of DCCP when used in VoIP admission control mechanisms and draw conclusions about the advantages and disadvantages of the proposed DCCP/CCID4 congestion control mechanism for use with VoIP applications

A cross-layer architecture to improve mobile host rate performance and to solve unfairness problem in WLANs

The evolution of the Internet has been mainly promoted in recent years by the emergence and pro- liferation of wireless access networks towards a global ambient and pervasive network accessed from mobile devices. These new access networks have introduced new MAC layers independently of the legacy "wire- oriented" protocols that are still at the heart of the pro- tocol stacks of the end systems. This principle of isola- tion and independence between layers advocated by the OSI model has its drawbacks of maladjustment between new access methods and higher-level protocols built on the assumption of a wired Internet. In this paper, we introduce and deliver solutions for several pathologi- cal communication behaviors resulting from the malad- justment between WLAN MAC and higher layer stan- dard protocols such as TCP/IP and UDP/IP. Specially, based on an efficient analytical model for WLANs band- width estimation, we address in this paper the two fol- lowing issues: 1) Performance degradation due to the lack of flow control between the MAC and upper layer resulting in potential MAC buffer overflow; 2) Unfair bandwidth share issues between various type of flows. We show how these syndromes can be efficiently solved from neutral "cross layer" interactions which entail no changes in the considered protocols and standards

An interaction between congestion-control based transport protocols and MANET routing protocols

Problem statement: Although many efforts have been done on studying the behaviour of TCP in MANET, but the behaviour of TFRC remain unclear in MANET. The purpose of this research is two folds.First, we studied the behaviour of TFRC and TCP over AODV and DSR as the underlying routing protocols in terms of throughput, delay and jitter.The second objective was to identify whether MANET routing protocols have an impact on transport protocols or not.Approach: Network Simulator 2 (NS-2) was used to conduct all of the experiments, i.e., TFRC over AODV, TFRC over DSR, TCP over AODV and TCP over DSR.We created 30 nodes on a 1000×1000 m location area and each node was assigned CBR traffic, transport protocol and routing protocol.In order to simulate the nodes mobility, we implemented a Random Waypoint mobility model with varying speeds of 5, 10, 15 and 20 m sec−1 (m/sec) with a 10 sec pause time.Results: We observed that TFRC throughput increases almost 55% when using DSR as its routing protocol, but TCP throughput has no significant difference with different underlying protocols.However, in terms of jitter and delay, both routing protocols, i.e., AODV and DSR have the impact of more than 50% on TFRC and TCP. Conclusion/Recommendations: The results obtained also show us that TFRC or TCP should choose AODV as its routing protocol because it has less jitter which is one of the critical performance metrics for multimedia applications

Q-AIMD: A Congestion Aware Video Quality Control Mechanism

Following the constant increase of the multimedia traffic, it seems necessary to allow transport protocols to be aware of the video quality of the transmitted flows rather than the throughput. This paper proposes a novel transport mechanism adapted to video flows. Our proposal, called Q-AIMD for video quality AIMD (Additive Increase Multiplicative Decrease), enables fairness in video quality while transmitting multiple video flows. Targeting video quality fairness allows improving the overall video quality for all transmitted flows, especially when the transmitted videos provide various types of content with different spatial resolutions. In addition, Q-AIMD mitigates the occurrence of network congestion events, and dissolves the congestion whenever it occurs by decreasing the video quality and hence the bitrate. Using different video quality metrics, Q-AIMD is evaluated with different video contents and spatial resolutions. Simulation results show that Q-AIMD allows an improved overall video quality among the multiple transmitted video flows compared to a throughput-based congestion control by decreasing significantly the quality discrepancy between them

Greediness control algorithm for multimedia streaming in wireless local area networks

This work investigates the interaction between the application and transport layers while streaming multimedia in a residential Wireless Local Area Network (WLAN). Inconsistencies have been identified that can have a severe impact on the Quality of Experience (QoE) experienced by end users. This problem arises as a result of the streaming processes reliance on rate adaptation engines based on congestion avoidance mechanisms, that try to obtain as much bandwidth as possible from the limited network resources. These upper transport layer mechanisms have no knowledge of the media which they are carrying and as a result treat all traffic equally. This lack of knowledge of the media carried and the characteristics of the target devices results in fair bandwidth distribution at the transport layer but creates unfairness at the application layer. This unfairness mostly affects user perceived quality when streaming high quality multimedia. Essentially, bandwidth that is distributed fairly between competing video streams at the transport layer results in unfair application layer video quality distribution. Therefore, there is a need to allow application layer streaming solutions, tune the aggressiveness of transport layer congestion control mechanisms, in order to create application layer QoE fairness between competing media streams, by taking their device characteristics into account. This thesis proposes the Greediness Control Algorithm (GCA), an upper transport layer mechanism that eliminates quality inconsistencies caused by rate / congestion control mechanisms while streaming multimedia in wireless networks. GCA extends an existing solution (i.e. TCP Friendly Rate Control (TFRC)) by introducing two parameters that allow the streaming application to tune the aggressiveness of the rate estimation and as a result, introduce fair distribution of quality at the application layer. The thesis shows that this rate adaptation technique, combined with a scalable video format allows increased overall system QoE. Extensive simulation analysis demonstrate that this form of rate adaptation increases the overall user QoE achieved via a number of devices operating within the same home WLAN

A Routing Delay Predication Based on Packet Loss and Explicit Delay Acknowledgement for Congestion Control in MANET

In Mobile Ad hoc Networks congestion control and prevention are demanding because of network node mobility and dynamic topology. Congestion occurs primarily due to the large traffic volume in the case of data flow because the rate of inflow of data traffic is higher than the rate of data packets on the node. This alteration in sending rate results in routing delays and low throughput. The Rate control is a significant concern in streaming applications, especially in wireless networks. The TCP friendly rate control method is extensively recognized as a rate control mechanism for wired networks, which is effective in minimizing packet loss (PL) in the event of congestion. In this paper, we propose a routing delay prediction based on PL and Explicit Delay Acknowledgement (EDA) mechanism for data rate and congestion control in MANET to control data rate to minimize the loss of packets and improve the throughput. The experiment is performed over a reactive routing protocol to reduce the packet loss, jitter, and improvisation of throughput