1. 8 July 2008
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [MAC Access Priorities]
Date Submitted: [8 July 2008]
Source:
[Benjamin A. Rolfe] Company [Blind Creek Associates]
Address [] Voice:[ ]
Re: []
Abstract: Discussion of a proposal to add prioritized channel access to the MAC.
Purpose: To stimulate discussion I task group 15.4e
Notice: This document has been prepared to assist the IEEE P 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 acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
Ben Rolfe

2. Channel Access Priorities
8 July 2008
Channel Access Priorities
Overview
Benjamin A. Rolfe
Ben Rolfe

3. Summary/Contents Purpose and Goals Kinds of Priority 8 July 2008
Ben Rolfe

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Purpose and Goals
Purpose
Stimulate Task Group discussion
Goals of prioritized access:
Improved QoS
Improve channel usage effectiveness
Save power
Improved coexistence
More robust system
Ben Rolfe
<author>, <company>

5. Types of Priority User Priority (Traffic Class, etc)
8 July 2008
Types of Priority
User Priority (Traffic Class, etc)
Assigned by Higher Layer Entities
Based on kind of payload
Channel Access Priority
Determined by the MAC
Based on NHL parameters and known conditions
Ben Rolfe

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MAC-SAP
MAC data request
User Priority (Traffic Class)
Other control parameters?
Ben Rolfe
<author>, <company>

7. Channel Access Priority (Cpri)
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Channel Access Priority (Cpri)
Cpri can take into account (for example)
User Priority and Parameters
Remaining time to live (TTL)
Likelihood of Success
Fairness
Cpri used to
Figure which frame goes next
Modify CSMA (Contention Access)
Ben Rolfe
<author>, <company>

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Channel Access
Contention Based
Cpri modified CSMA
Back-off extension to ‘listen’ period (d/Cpri)
Higher priority “wins”
Can lead to fewer collisions
Contention Free
What goes next
Clean out old/hopeless frames
Ben Rolfe
<author>, <company>

9. Backwards Compatibility
8 July 2008
Backwards Compatibility
Channel Access
CSMA not broken:
Legacy nodes look like high Cpri
No impact on receiver
MPIB parameters:
Number of U-pri / Pri-enabled
MAC-SAP: optional parameters
Ben Rolfe

10. Fitting the 802.15.4 Architecture
8 July 2008
Fitting the Architecture
Keeping it Simple
Info from higher layers
More MAC memory (Queues)
Timing mechanism (coarse)
Minimal extension to CSMA algorithm
Ben Rolfe

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The End
Thanks
Ben Rolfe
<author>, <company>