1. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 1 Submission Paul Dixon, Hisilicon Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [The Effect of Failures on QoS] Date Submitted: [Sep 5, 2008 ] Source: [Paul Dixon] Company: [Hisilicon] Address: [1700 Alma Drive, Plano, TX 75075] Voice:[+1 469 229 5374], E-Mail:[pdixon@huawei.com] Re: [IEEE 802.15.4e group] Abstract:[This presentation examines the relationship between reliability and QoS.] Purpose:[To aid in common usage of terms relating to Reliability and QoS.] Notice:This document 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 acknowledges and accepts that this contribution becomes the property of the Working Group for WPANs and may be made publicly available by WPAN.

2. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 2 Submission Paul Dixon, Hisilicon Outline Reliability Quality of Service Fault Tolerance

3. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 3 Submission Paul Dixon, Hisilicon Motivation There appears to be much non-standard use of terms and a misunderstanding in some quarters of the relationship between Reliability and QoS This presents a brief overview of these issues to ensure a common understanding

4. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 4 Submission Paul Dixon, Hisilicon Reliability reliability is the ability of a system to perform and maintain its functionality in under normal circumstances A system which does not do this may be said to have failed

5. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 5 Submission Paul Dixon, Hisilicon Reliability Failures come in two main types, hard and soft A hard failure occurs when a fault develops in the systems and renders it incapable of performing its function A soft failure is a short term failure due some unpredictable circumstance but functionality is unimpaired in the long term

6. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 6 Submission Paul Dixon, Hisilicon Quality of Service Quality of Service is about achieving goals There is a need to deliver a stream of data between two points The requirements of said stream need to be predictable Delivery of such data is a real time scheduling issue

7. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 7 Submission Paul Dixon, Hisilicon Quality of Service This is not synonymous with reliability Reliable operation is required for file transfer and higher level protocols are very good in ensuring reliable delivery is achieved But in what time?

8. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 8 Submission Paul Dixon, Hisilicon Fault Tolerance Fault tolerance is a totally different issue A different level of cost and complexity

9. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 9 Submission Paul Dixon, Hisilicon Fault Tolerance While a fault tolerant system could probably be configured from 802.15 components, 802.15 systems are not fault tolerant in the normal use of the term An 802.15 system has some resilience to faults and may in a reasonably short time reconfigure its routing to overcome a failure

10. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 10 Submission Paul Dixon, Hisilicon Summary Reliability is important, without a certain level of reliability, a usable system cannot be configured QoS provides a mechanism to deliver information in a timely manner in the absence of other disturbances True Fault Tolerance provides performance which is identical whether or not faults exist Some level of resilience is providing allowing systems to continue after reconfiguration

11. Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 11 Submission Paul Dixon, Hisilicon Thank you!