1. MRG for mesh Date: July 2010 Authors: July 2010 July 2010
Ivan Pustogarov, IITP RAS
Ivan Pustogarov, IITP RAS

2. Abstract MRG purpose and its potential application in mesh
July 2010
July 2010
Abstract
MRG purpose and its potential application in mesh
Multicast-in-mesh overview (either unreliable or with high overhead)
Example of more efficient multicast approach that MRG can benefit
Ivan Pustogarov, IITP RAS
Ivan Pustogarov, IITP RAS

3. MRG purpose and its potential
July 2010
MRG purpose and its potential
MRG is intended to make audio&video multicast transmissions more reliable and hence more efficient.
Currently MRG is defined for infrastructure mode only
MRG can become a basis on top of which more efficient multihop multicast proprietary mechanisms can be built in mesh
Ivan Pustogarov, IITP RAS

4. July 2010
Multicast and mesh
According to the PAR, .11s networks are intended to carry unicast, broadcast and multicast traffic.
Audio and video multicast
Topology control multicast
Ivan Pustogarov, IITP RAS

5. Multicast approaches in mesh
July 2010
Multicast approaches in mesh
Two approaches exist in .11s on how to organize multicast traffic delivery to the intended receivers
Unreliable Multicast frames are broadcasted
Nonscalable Multicast frames are converted to unicast frames
Ivan Pustogarov, IITP RAS

6. Example of more efficient approach
July 2010
Example of more efficient approach
Multicast tree approach can be used to decrease total number of retransmissions :
We exploit broadcast nature of the medium and use one-hop multicast in branch points.
NOTE: Branch points determine the next stations in the route according to a proprietary tree setup mechanism
Do we have appropriate tools to implement such an approach?
Improved Multicast tree approach (only one multicast packet transmission in branchpoints).
Ivan Pustogarov, IITP RAS

7. MRG-BlockAck as a building block for efficient multicast in mesh
July 2010
MRG-BlockAck as a building block for efficient multicast in mesh
In the example of multicast tree approach:
Group addressed MCCA reservation can be used to protect one-hop multicast traffic from collisions with packets sent by stations in the two-hop neighborhood, BUT:
Currently no ARQ-like mechanism exists to react on multicast transmission errors. Hence:
audio/video quality may degrade significantly due to packet losses.
topology control frames may be lost which leads to broken routes.
One solution is to use MRG-BlockAck
Ivan Pustogarov, IITP RAS

8. July 2010
MRG-BlockAck in mesh
Current MRG-BlockAck procedure is suitable for usage in mesh
We propose to change draft text so that MRG can be used in mesh.
Modest changes should be made to the draft (such as replace “AP” with “Groupcast source” in section )
MRG-BlockAck in mesh can become a basis on top of which efficient and reliable multicast delivery can be organized.
Ivan Pustogarov, IITP RAS

9. Strawpoll Should MRG procedure be adapted to be used in mesh networks?
July 2010
Strawpoll
Should MRG procedure be adapted to be used in mesh networks?
Yes:
No:
Abs.:
Ivan Pustogarov, IITP RAS

10. Acknowledgements July 2010
The proposal was made in the framework of FP7 project “Flavia”.
Ivan Pustogarov, IITP RAS

11. July 2010
Backup slides
Ivan Pustogarov, IITP RAS

12. Example of draft change
July 2010
Example of draft change
Ivan Pustogarov, IITP RAS