1. Team: Aaron Sproul Patrick Hamilton
Wireless VoIP
Team:
Aaron Sproul
Patrick Hamilton

2. Outline Context & Problem Overview of VoIP Method
WinEyeQ Screenshots (QoS program)
Results
Demo of VoIP calls
Conclusions
Summary/Lessons learned/Future work

3. Context & Problem Context for problem Project motivation
Limitations of a wireless VoIP call versus a wired VoIP call
Project motivation
Voice over IP is going mainstream
Vonage, Skype
WiFi Hotspots on the rise
Greater than 100,000
Project problem definition
Capacity limitation of Wireless VoIP
Using b
Using g
Affect of WEP encryption on Calls
More precise characterization of VoIP quality factors

4. Overview of VoIP Invite SIP – Session Initiation Protocol 200 OK ACK
Application-layer control (signaling) protocol
Used for creating, modifying, and terminating sessions
Reduced Complexity - SIP has only six methods
transport independent – used with UDP, TCP, ATM, etc.
Low overhead - text based
Overview of VoIP performance characteristics
Jitter is an abrupt or unwanted variation of one or more signal characteristics (variation in delay)
Packet loss, Delay, network latency
200 OK
ACK
RTP Traffic
BYE
200 OK

5. Overview of VoIP (2) R-Factor: 0-100 (Trans. Quality Rating)
MOS Factor:
1-5 (Subjective)

6. Method LAN Programs Used:
SJPhone – PC-to-PC calling
Iperf – simulates background traffic
WinEyeQ - analyze and obtain VoIP QoS parameters
Router: Linksys WRT54GC Compact Broadband Router
Call Analysis Steps:
Start WinEyeQ capturing traffic
Begin call through SJPhone
Begin Iperf with set number of background streams
Wireless Settings Tested:
802.11b with and without WEP
802.11g with and without WEP
Codec Used:
G.711 A-Law Codec (64 Kbps)

9. Toll Quality (Normal Land Line Quality)
Results: R-Factor
Toll Quality (Normal Land Line Quality) 70

10. Results: MOS Factor
Toll Quality
3.6

11. Results: Packet Count
Fewer collisions in g only network because of increase in bandwidth throughput

12. Results: Average Jitter (ms)
B only – randomness??
Jitter means that there is a longer delay between packet arrivals, another sign of congestion

13. Results: Average Packet Intervals (ms)

14. Results: Average Bandwidth (kbps)
G maintained full bandwidth usage of ~64 kbps for more calls

15. Demonstration of VoIP calls
B only
B with WEP
G only
G with WEP
New Iperf session added every 10 seconds

16. Conclusions Wireless G allows only 1 more call WEP effects:
We used Highest Quality Codec (bandwidth intensive)
WEP effects:
Wireless B: Negative effect on call capacity and quality
Wireless G: No effect on call capacity or quality

17. Summary
Using an encrypted wireless G capable access point allows for best possible call quality and capacity.
Lessons learned
Booming Industry
Limited Capability of single WiFi hotspot
Future Work
Addition of more interfaces
Quality versus Bandwidth usage (codec)
Better Encryption methods for VoIP

18. Questions?