QoS Studies of VoIP over WiMax

Paper Summary:

This paper examines the three main components of a VoIP system - including the sender or source of VoIP data streams, the receiver or destination point, and the transmission and the network. It specifically looks at the characteristics, parameters and constraints affecting VoIP quality over WiMAX-based networks and discusses the methods designed to improve the median level of VoIP communications by optimizing voice encoding parameters and measuring their performance using R Factor and MOS. The paper includes tables and figures.

Table of Contents:
Methodology
Introduction
Problem Statement
Using MOS Measurements of VoIP Call Performance
Data Analysis Tools
Statistical Sampling of Respondents
Assumptions, Parameters of Methodology
Summary
Chapter 2
Chapter on Results
Introduction
R-Value and MOS Level Interrelationships
Compensating for Randomized Packet Loss
Summary

From the Paper:

"Increasing the voice payload size of compressed speech over VoIP-based sessions relying on static IP addresses requires even less resources per call than when DHCP-based VoIP calls are made over WiMAX-based networks. Clearly, augmenting the voice payload size with no compression still provides better resulting quality; which is a luxury on low-use networks that is, as can be seen from this study, fairly unrealistic to assume in typical configurations. This aspect of the study also shows that variation of speech encoding parameters is not efficient in the case of a single call or a relatively small portion of VoIP-based WiMAX calls. If more voice streams can be managed simultaneously through the use of MPDU routing, increasing the voice payload size provides better resulting quality in networks congested with both voice and data networks."

Sample of Sources Used:

• R. Beuran, M. Ivanovichi, (2004) "User-Perceived Quality Assessment for VoIP Applications", Technical Report.
• Xavier Perez-Costa, Daniel Camps-Mur, Albert Vidal. (2007). On distributed power saving mechanisms of wireless LANs 802.11e U-APSD vs 802.11 power save mode. Computer Networks, 51(9), 2326. Retrieved August 22, 2008, from ABI/INFORM Global database. (Document ID: 1263867791).
• Thomas Enderes, Swee Chern Khoo, Clare A. Somerville, Kostas Samaras. (2002). Impact of Statistical Multiplexing on Voice Quality in Cellular Networks. Mobile Networks and Applications, 7(2), 153-161. Retrieved August 12, 2008, from ABI/INFORM Global database. (Document ID: 404996251).
• Kevin Fitchard (2008, January). VOIP LOOKS TO WIMAX. Telephony, 249(1), 28. Retrieved August 12, 2008, from ABI/INFORM Global database. (Document ID: 1431340971).
• Tobias Hossfeld, Andreas Binzenhofer. (2008). Analysis of Skype VoIP traffic in UMTS: End-to-end QoS and QoE measurements. Computer Networks, 52(3), 650. Retrieved August 10, 2008, from ABI/INFORM Global database. (Document ID: 1424672321).

More papers on QoS Studies of VoIP over WiMax:

• Case Study # 104594 : "Quality of Service of Voice over Internet Protocol"
• Dissertation or Thesis # 98382 : "The Economic Impact of VOIP"
• Term Paper # 104315 : "The History of VoIP Technology"

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