1. Proposed ERTS & ECTS Mechanisms
Month 2000
doc.: IEEE /xxx
March 2001
Proposed ERTS & ECTS Mechanisms
Author:
Matthew Sherman
AT&T Labs - Research
180 Park Avenue
Florham Park, NJ
Date: March 12, 2001
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

2. Problem addressed 802.11e is developing mechanisms to support QoS
Month 2000
doc.: IEEE /xxx
March 2001
Problem addressed
802.11e is developing mechanisms to support QoS
Many situations when the ability to cause groups of STA to cease transmissions would be useful
Accommodate TBTT for Beacon transmission
Accommodate protocol enhancements / coexistence
HCF / Token passing schemes, Bluetooth, HIPERLAN, etc
Hidden terminals
Overlapped BSS mitigation
Would like technique applied to also work with Legacy STA (LSTA)
Would like ability to differentiate between Legacy and groups of e STA (ESTA)
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

3. Approach to Problem Develop method to Set NAV in a STA group
Month 2000
doc.: IEEE /xxx
March 2001
Approach to Problem
Develop method to Set NAV in a STA group
Develop method to Reset NAV in a STA group
Deferred to later meeting
Use existing frame formats as much as possible
Enhances compatibility with LSTA
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

4. Approach to Problem (Cont.)
Month 2000
doc.: IEEE /xxx
March 2001
Approach to Problem (Cont.)
Play with usage / interpretation of RTS & CTS
Later CF-End as well
Have ESTA use Addresses for qualifiers and signaling
Apply Duration field based on contents of Addresses
Based signaling / qualifiers on Address types
Unicast
Multicast
Broadcast
Chose mappings that are consistent with current usage of address fields in standard
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

5. Suggested ECTS Mechanisms
Month 2000
doc.: IEEE /xxx
March 2001
Suggested ECTS Mechanisms
Enhance CTS (ECTS) usage to allow setting Duration/ID field to any valid Duration value
Broadens context for Duration field use
Enhance CTS usage to allow any valid address in RA field
LSTA will always set NAV for duration indicated
Rules for Compliant ESTA will vary (See Chart)
Non-compliant ESTA act as LSTA
Allow use of PIFS with this message for preferential media access (EAP / EPC only)
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

6. Map of New Capabilities (CTS)
Month 2000
doc.: IEEE /xxx
March 2001
Map of New Capabilities (CTS)
Message RA
Effect (LSTA always set NAV)
CTS
Unicast
Set NAV
Unicast (Self)
Multicast
Set NAV if in Group
Broadcast
Set NAV if legacy
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

7. Suggested ERTS Mechanism
Month 2000
doc.: IEEE /xxx
March 2001
Suggested ERTS Mechanism
Enhance RTS (ERTS) usage to allow setting Duration/ID field to any valid Duration
Broadens context for Duration field use
Enhance RTS usage to allow group addresses in TA field
LSTA will always set NAV for duration indicated
Compliant ESTA do not set NAV if not in group
Non-compliant ESTA act as LSTA
ESTA forward CTS if addressed in RA
Allow use of PIFS with this message for preferential media access (EAP / EPC only)
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

8. Map of New Capabilities (RTS)
Month 2000
doc.: IEEE /xxx
March 2001
Map of New Capabilities (RTS)
Message TA RA
Effect on ESTA (LSTA always set NAV)
RTS
unicast1
Reserved
unicast2
Set NAV, Respond CTS, Obey NAV for CTS
multicast1
broadcast
Set NAV if Group, send CTS to Group, ignore NAV for CTS
multicast2
multcast1
Broadcast
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

9. What Enhancements Accomplish
Month 2000
doc.: IEEE /xxx
March 2001
What Enhancements Accomplish
If no LSTA
Can set NAV independently in any group of ESTA
Some ability to control remote groups via RTS/CTS relay
Since can have “Group” of one, can set for single ESTA as well
If LSTA are present
Must treat as special case
Always part of addressed group
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

10. Comments on Mechanisms
Month 2000
doc.: IEEE /xxx
March 2001
Comments on Mechanisms
No new frame formats required
Fully backward-compatible
Additional RTS mappings possible
Open to other mappings
Open to partial acceptance of mappings
Implementation of mechanisms are optional
Indicating support of mapping mandatory in ESTA
Duration field in other frame types could also be used to reserve channel
RTS/CTS seemed most appropriate
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

11. Comments specific to Overlapped BSS
Month 2000
doc.: IEEE /xxx
March 2001
Comments specific to Overlapped BSS
Goal of new mappings is to allow suppression of groups of terminals in overlap
Technique assumes ability exists to assign terminals to groups
Currently those techniques are considered beyond
Techniques are identified in 802.1
Best if applied with ability to solicit interference info from STA
Which other STA are heard at what power level
Mechanisms being developed using Generic Action Frame
Existing proposed elements may need to be enhanced
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

12. Example Applications of
March 2001
Example Applications of
New Mechanisms
Matthew Sherman, AT&T Labs - Research

13. Example ECTS Usage Reduction of TBTT Overrun*
Month 2000
doc.: IEEE /xxx
March 2001
Example ECTS Usage Reduction of TBTT Overrun*
ECTS B
Prior TX
PIFS
TBTT
NAV Set by Legacy STA
Legacy Tx
Suppressed
ETx1
RA=Broadcast
ETx2
ETxN
* Assumes ESTA knows not to overrun TBTT
ETxX are transmissions by ESTA
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

14. Example ECTS Usage Sharing with Unknown Protocol
Month 2000
doc.: IEEE /xxx
March 2001
Example ECTS Usage Sharing with Unknown Protocol
ECTS
Prior Tx
PIFS
NAV Set by all STA
Unsolicited Tx Suppressed
Unknown or Foreign Protocol
RA=Senders Address
Duration Expires
(NAV Resets)
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

15. Example Usage - BSS Overlap*
Month 2000
doc.: IEEE /xxx
March 2001
Example Usage - BSS Overlap*
Legend:
Group 12 - ESTA in BSS1 that interfere with BSS2
Group 21 - ESTA in BS21 that interfere with BSS1
Tx Transmissions from any BSS 1 STA
Tx Transmissions from any BSS 2 STA
Tx Transmission from BSS 1 STA not in overlap
Tx Transmission from BSS 2 STA not in overlap
BSS2
BSS1
ECTS
Tx2
RA=Group 21
BSS2 Group 21 Suppressed
Tx to/from ESTA in overlap
Tx12
RA=Group 12
Tx21
Tx1
BSS1 Group 12 Suppressed
* Multicast addresses for groups 1 and 2 need not be assigned
(Never necessary to suppress groups 1 or 2)
Matthew Sherman, AT&T Labs - Research
John Doe, His Company

16. Example Usage Hidden STA Suppression*
Month 2000
doc.: IEEE /xxx
March 2001
Example Usage Hidden STA Suppression*
ECTS
RA=Group A
ERTS
TA=Group A
RA=RSTA
Hidden Node
Suppressed
Hidden STA suppressed
Continued
Suppression
* Assumes Hidden ESTA is only STA in group to begin with (Group A)
Matthew Sherman, AT&T Labs - Research
John Doe, His Company