1. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 1 Test Methodology for Measuring Loss, Delay and Jitter Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2006-01-9 Authors:

2. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 2 Abstract This presentation is the companion presentation for document 11-06/0004r0, which contains text for inclusion into the TGT draft. In these documents, test methodologies for measuring the packet loss, packet latency and packet jitter are proposed.

3. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 3 Purpose of the Tests Packet Loss, Packet Latency and Packet Jitter are all secondary metrics that are key in characterizing the behavior of latency-sensitive usage cases such as VOIP, video conferencing and Internet gaming. Characterization of Packet Loss, Packet Latency and Packet Jitter in a DUT or a system provides important information to system designers and planners –“What is the probability of a codec jitter buffer under run?” –“Is the packet delay adequate for my application to run?” Results presented in form of cumulative distribution function (CDF) enable these questions to be answered directly

4. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 4 Packet Loss Packet Loss is a secondary metric that measures packets lost in transmission over a data network between two network endpoints. The Packet Loss Metric is defined as a percentage: The number of packets lost divided by the number of packets expected. Packet Transmission: Packet 1 Packet Reception: Packet 2Packet 3Packet 4 Packet 1Packet 2Packet 4

5. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 5 Packet Delay Latency is a secondary metric that measures the latency between the transmission and the reception of a data packet between two network endpoints. Latency is measured in seconds. Transmitter Data Network Receiver packet is transmitted packet is received Packet Latency

6. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 6 Packet Jitter Jitter is a secondary metric. Jitter is an estimate of the statistical variance of data packet interarrival time. This will be calculated using the formula presented in section 6.3.1 of RFC 1889 for interarrival jitter. Packet Transmission: 10 ms Packet 1Packet 2Packet 3Packet 4 10 ms Packet Reception: 11 ms Packet 1Packet 2Packet 3Packet 4 9 ms11 ms

7. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 7 Packet Jitter Calculation The interarrival jitter J is defined to be the mean deviation (smoothed absolute value) of the difference D in packet spacing at the receiver compared to the sender for a pair of packets (RFC 1889). The formula presented in section 6.3.1 of RFC 1889 for interarrival jitter is used.. Example using the illustration on Slide 6: D(1,2) = (T2 – T1) – (A2 – A1) Where D(1,2) is the difference between packets 1 and 2. T2 and T1 are the transmit times of packets 1 and 2. A2 and A1 are the arrival times of packets 1 and 2. Jitter is recalculated every time D is calculated. In this example, the jitter calculation starts after packet 2 is received. J = J + ( | D | ) / 16 After packet two is received, D can be calculated as follows: 10 – 11 = -1. The initial value for J is zero, so J = 1 / 16. After packet three is received, D can be calculated as 10 – 9 = 1. The new D value is then plugged into the jitter function as follows: J = 1/16 + (1/16) = 1/8.

8. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 8 STA Test Configuration Latency-Sensitive Traffic 802.11 Traffic Analyzer STA UT AETE or off-the-shelf AP RF Cables Variable Attenuator Legend: AETE – AP Emulation Test Equipment

9. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 9 STA Test Configuration The STA Test Configuration is ideal for testing STA in a controlled environment with a limited number of variables. The AP Emulation Test Equipment (AETE) or off-the- shelf AP can be used.

10. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 10 AP Test Configuration SETE-2 or additional 802.11 STAs 802.11 and DS Traffic Analyzer DS Traffic Generator (optional) AP / UT SETE-1 or 802.11 STA (i.e., VOIP phone) Latency-Sensitive Traffic Background and Latency-Sensitive Traffic Application Node (i.e., VOIP phone) Latency-Sensitive Traffic Background and Latency-Sensitive Traffic Application Specific Server (i.e., VOIP server) if applicable RF cables Variable Attenuator Legend: Wired LAN cables SETE – Station Emulation Test Equipment

11. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 11 AP Test Configuration The AP Test Configuration is ideal for AP capacity as it relates to packet loss, latency and jitter. The STA Emulation Test Equipment (SETE) is useful for introducing additional capacity and traffic types into the AP Test. The 802.11 and DS traffic analyzers must have synchronized time-stamps in order to properly calculate packet latency.

12. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 12 Packet Loss Results from VOIP Test

13. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 13 Packet Loss Results from VOIP Test

14. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 14 Packet Delay Results from VOIP Test

15. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 15 Packet Delay Results from VOIP Test

16. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 16 Packet Jitter Results from VOIP Test

17. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 17 Packet Jitter Results from VOIP Test

18. doc.: IEEE 802.11-06-0005-01-000t Submission Jan 2006 Chris Trecker, Azimuth SystemsSlide 18 Motion Move to adopt the contents of document 11-06-0004/r0 into the P802.11.2 draft. Technical (75%) Y: N: A: