1. Directed Multicast Service (DMS)
Month Year
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE yy/xxxxr0
September 2008
Directed Multicast Service (DMS)
Authors:
Date:
Slide 1
Emily Qi (Intel Corp) et al
Page 1
Emily Qi
John Doe, Some Company

2. Directed Multicast: Motivation
Month Year
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE yy/xxxxr0
September 2008
Directed Multicast: Motivation
Enable aggressive and flexible client power saving
Sleeping STA doesn’t need to wake up at every DTIM or FBMS interval to receive multicast frames
Sleeping STA only need to wake up to check AID TIM bit at a desirable interval (e.g. listen interval)
Other benefits:
Protect directed multicast by using the client’s negotiated Pairwise cipher with the AP
Today, multicast is protected by the lowest common (or open) authentication
Enable reliable service
Unicast is more reliable than multicast
Slide 2
Emily Qi (Intel Corp) et al
Page 2
Emily Qi
John Doe, Some Company

3. Directed Multicast Service (DMS) Overview
Month Year
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE yy/xxxxr0
September 2008
Directed Multicast Service (DMS) Overview
STA advertises Directed Multicast Service (DMS) Capability
Non-AP STA sends a request to specify traffic classes (i.e multicast address) for the directed multicast traffic delivery
AP may accept or reject the traffic class specified by the non-AP STA
If the service is accepted by the AP,
AP shall transmit the requested group addressed (multicast) traffic as the individual addressed (unicast) traffic to the requesting STA in an A-MSDU frame format, and AP may still transmit the group addressed traffic for other STAs within the multicast group in the BSS as normal.
The requesting STA shall discard group addressed frame that matches a multicast address entry of the list.
Other STAs will process group addressed traffic as normal.
See doc 08/0050r3
Slide 3
Emily Qi (Intel Corp) et al
Page 3
Emily Qi
John Doe, Some Company

4. DMS Request and Response frames
Month Year
doc.: IEEE yy/xxxxr0
September 2008
DMS Request and Response frames
DMS Request frame:
Category
Action
Dialog Token
Request Type (“Add” or “Remove”)
DMS Descriptor List
Octets: 1
variable
DMSID
Length
TCLAS Elements (optional)
TCLAS Processing Element (optional)
Octets: 1
variable 3
DMS
Descriptor
DMS Response frame:
Category
Action
Dialog Token
DMS Status List
Octets: 1
DMS Status
DMSID
DMS Status
Octets: 1
Emily Qi (Intel Corp) et al
Slide 4
Emily Qi

5. A-MSDU is used for Directed Multicast
June 2007Month Year
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE yy/xxxxr0
September 2008
A-MSDU is used for Directed Multicast
Original destination address (DA) is transmitted in A-MSDU subframe header (the DA field)
The DA and SA fields of the A-MSDU subframe header contain the values passed in the MA-UNITDATA.request and MA-UNITDATA.indication primitives. (e.g. DA=multicast address)
RA (Address 1) in the MAC header is set to the requesting non-AP STA address
Support of A-MSDU processing is mandatory according to the IEEE n specification.
Emily Qi (Intel Corp) et al
Zhen Xie, Atheros, et al.John Doe, Some Company
Page 5
Zhen Xie, Atheros, et al.John Doe, Some Company
Emily Qi

6. Question 1: Directed Multicast is not scalable
Month Year
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE yy/xxxxr0
September 2008
Question 1: Directed Multicast is not scalable
Not scalable
DMS provides power saving and same level of reliability as unicast for traffic classes, at the cost of bandwidth
Solutions
Limit the service for less than x associated STAs
Enable this feature in the environment with less than x associated STAs, for example, home environment
Allow AP to disable/reject this service when the limit is reached
Again this is an optional feature.
Slide 6
Emily Qi (Intel Corp) et al
Page 6
Emily Qi
John Doe, Some Company

7. Month Year
doc.: IEEE yy/xxxxr0
September 2008
Question 2: TGv vs. TGaa
The issue was raised that Directed Multicast proposal may overlap with TGaa Scope:
“Improved link reliability and low jitter characteristics for multicast/broadcast audio/video streams.”
DMS should be considered in TGv:
DMS adds to existing multicast enhancements in TGv, naturally fits in TGv; DMS addresses TGv objective [Req 2120]
Including DMS in TGv can benefit low bandwidth applications sooner
Including DMS in TGv should also benefit TGaa
Straw Poll taken in the May TGv/TGaa joint meeting:
Directed multicast proposal ( )should be considered in:
TGv:25; TGaa:8; abstain: 8
Emily Qi (Intel Corp) et al
Emily Qi

8. Other Questions? September 2008 Month Year doc.: IEEE 802.11-yy/xxxxr0
Slide 8
Emily Qi (Intel Corp) et al
Emily Qi

9. Existing Multicast Enhancements in TGv
Month Year
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE yy/xxxxr0
September 2008
Existing Multicast Enhancements in TGv
FBMS – Flexible Broadcast/Multicast Service
Enables flexible delivery interval for broadcast/multicast as STA’s request (at multiples of the DTIM intervals)
Enables group addressed frames to be transmitted at higher data rates, reducing the amount of basic rate traffic sent over the radio link.
Multicast Diagnostics Reporting
STA provides the AP an indication of the number of dropped group addressed frames in order to enable reliable service
DMS adds to existing multicast enhancements in TGv, naturally fits in TGv
Slide 9
Emily Qi (Intel Corp) et al
Page 9
Emily Qi
John Doe, Some Company

10. DMS and 802.11aa targets different applications space
Month Year
doc.: IEEE yy/xxxxr0
September 2008
802.11aa Requirements
Reliable Multicast is a complex problem, and different applications may require different solutions.
DMS provides same level of reliability as unicast for all traffic classes, at the cost of bandwidth
Directed multicast can be used while streaming a multicast Standard Definition (SD) stream to 2 or 3 STAs, it does not scale well for High Definition (HD) video streaming.
802.11aa targets B/M robustness (reliability is a part of robustness) for HD video streaming (high bandwidth) applications
.11n is sufficient for Standard Definition video streaming
DMS targets low bandwidth applications, which is not the target of aa
DMS and aa targets different applications space
Emily Qi (Intel Corp) et al
Emily Qi

11. DMS should be considered in TGv
Month Year
doc.: IEEE yy/xxxxr0
September 2008
DMS should be considered in TGv
DMS addresses TGv objective [Req 2120], complements TGv FBMS
FBMS provides power saving for TGv devices. However, the legacy device (non-TGv device) within the BSS will experience unexpected B/M delivery delay.
DMS provides power saving for TGv devices without introducing latency on the legacy (non-TGv) device. However, its usage is limited to a small number of associated STAs due to bandwidth requirements.
Including DMS in TGv can benefit low bandwidth applications sooner
TGv is in the process of initial ballots, expected sponsor ballot in Jan-09
TGaa is at the stage of calling for proposals, expected sponsor ballot Nov-10
Including DMS in TGv should also benefit TGaa
All features (e.g. DMS) specified in the existing draft standard and draft amendments (e.g. TGv) can be utilized by later amendments (e.g. TGaa)
Emily Qi (Intel Corp) et al
Emily Qi