Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 1 Submission Paul Dixon,...

Submission Paul Dixon, Hisilicon

Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS

Slide 1

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)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:[[email protected]]

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.



Slide 2

Outline

• Reliability

• Quality of Service

• Fault Tolerance



Slide 3

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



Slide 4

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



Slide 5

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



Slide 6

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



Slide 7

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?



Slide 8

Fault Tolerance

• Fault tolerance is a totally different issue

• A different level of cost and complexity



Slide 9

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



Slide 10

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



Slide 11

Thank you!

Sep. 2008 doc.: 15-08-0632-00-004e-The Effect of Failures on QoS Slide 1 Submission Paul Dixon,...

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