VoIP over Wireless Networks James Michaels Jonathan Levitt

Introduction Issues with wireless networks: Inability to provide QoS Unable to guarantee bandwidth Determine maximum number of quality VoIP calls over wireless networks

Background and Motivation VoIP(Voice over Internet Protocol) Routing of voice through any IP-based network VoIP Components: Codec converts analog voice to digital data and compresses it SIP (Session Initiation Protocol) to establish call connection

Preliminary Work Equipment: Hardware Software 2 Laptop computers (1 wired, 1 wireless) 1 Router/AP Software SJphone Iperf

Preliminary Work Testbed 10.1.2.2 10.1.2.1 10.1.1.1 10.1.1.11 10.1.1.2

Results Calls Error % Average Jitter (ms) 2 .12 1.20 3 .11 2.28 4 2.35 3.3 2.41 6 26.8 4.11 7 35.6 9.56 8 55.6 13.14 Calls: SJphone call + n(Iperf call) Error % = 100(Packet Loss / Packets Sent) Average Jitter = Summation of each Jitter / n(Iperf call)

Results Audio Comparison 1 Call 5 Calls 6 Calls 8 Calls

Perceptible, but not annoying Work To Be Done MOS (Mean Opinion Score): Subjective test where listeners rate the quality based on the following scale MOS Quality Impairment 5 Excellent Imperceptible 4 Good Perceptible, but not annoying 3 Fair Slightly annoying 2 Poor Annoying 1 Bad Very annoying

Work To Be Done R-Factor: Objective call quality measurement ITU developed E-model Ranges from 0-100 (100 = perfect quality) Score decreases based on amount of delay and equipment impairments Construct an advance monitoring metric Develop a program to measure and compare VoIP call quality while increasing the number of calls

Summary VoIP’s call quality diminishes as the number of calls are increased 5 is the maximum number of VoIP calls with less than 3.5% error Average jitter increases as the number of calls increase Questions?