Capacity Estimation of VOIP Channels on Wireless Networks

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Capacity Estimation of VOIP Channels on Wireless
Networks

• Baek Seung Jun
• Cui Ningzhou
• Ogale Vinit
• Park Ryoungsun
• Patel Tanmay

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Project Overview

• Project Goal
• Estimation of channel capacity with VoIP
  applications over wireless networks(802.11b)
• Measurement of channel characteristics (delay,
  jitter, packet loss) contributing to QOS for
  varying number of nodes

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VoIP
Introduction
Network (Internet)
Voice
Voice Encoder
Voice Decoder
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VoIP
Introduction

• Convergence of wired and wireless data networks
  with PSTN and cellular networks
• Issues with VoIP over Wireless Links
• Is the QOS comparable to traditional PSTN ?
• How many simultaneous users can the network
  support ?

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QoS

• What is QoS
• A metric which tries to measure the satisfaction
  level of the user
• Dependent on application
• Mean Opinion Score (MOS)
• A score of 1 to 5

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Voice Samples

• MOS 4.5 , 3.5 and 2.5

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Approach

• Simulation of the wireless network using ns2
• Measurement of capacity using the NetIQ Chariot
  network analysis tool

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ns2 Simulations
Approach

• Network Simulator 2
• Public domain network simulator
• Extension of Tcl
• Simulations
• Simulate a wireless network
• Generate VoIP data streams
• Vary number of nodes
• Measure the packet delays and jitter from the
  simulations and estimate the capacity for an
  acceptable QOS

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Capacity Measurements

• Capacity
• Small scale
• Interference limited
• Determined by acceptable call quality
• Call quality
• Latency, jitter, packet loss
• MOS (Mean Opinion scores)

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Chariot with VoIP Test Module

• Measures end-to-end performance
• Tests with real application loads
• Tests the capacity of the network
• Evaluates the effectiveness of QoS
• Overall voice quality (MOS)

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Measurement Setup
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Expected Outcome
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Expected Outcome
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