1. 802.11aa – OBSS Strategy and Plan
September 2008
doc.: IEEE /1003r0
March 2009
802.11aa – OBSS Strategy and Plan
Date:
Authors:
Ganesh Venkatesan, Intel Corporation
Alex Ashley, NDS Ltd

2. September 2008
November 2007
doc.: IEEE /2752r1
doc.: IEEE /1003r0
March 2009
Abstract
This submission is a document under developments. When completed, the document will address the following :
Definition of OBSS
Approaches to solution(s) for OBSS
General OBSS problem
Phased approach – a solution for a smaller OBSS configuration
Agree that OBSS is too big to solve and drop it from the PAR
Mechanisms to mitigate issues due to OBSS
Plan to complete the specification
Slide 2
Ganesh Venkatesan, Intel Corporation
Page 2
Alex Ashley, NDS Ltd
Peter Ecclesine, Cisco Systems

3. What is OBSS? OBSS Definitions:
September 2008
November 2007
doc.: IEEE /2752r1
doc.: IEEE /1003r0
What is OBSS?
March 2009
OBSS Definitions:
OBSS edge -- Any two APs operating in the same channel and can hear each other (either directly or via a STA associated to one of the APs)
OBSS Graph – is a graph where APs are nodes of the graph and the edges are OBSS edges and every AP with in the OBSS graph can be connected via one or more OBSS APs to every other AP in the OBSS graph
Length(OBSS graph) – longest shortest path between any two APs in the OBSS graph
Size(OBSS graph) – number of nodes (APs) in the OBSS graph
Scope of TGaa OBSS Solution (proposed in Los Angeles session) –
if length(OBSS graph) <= 2 and the size(OBSS graph) <=3 , enable the OBSS QAP solution otherwise (a) backoff to legacy (non .11aa) mode or (b) use a different solution
Slide 3
Ganesh Venkatesan, Intel Corporation
Page 3
Alex Ashley, NDS Ltd
Peter Ecclesine, Cisco Systems

4. Issues with the scope of OBSS solution?
September 2008
November 2007
doc.: IEEE /2752r1
doc.: IEEE /1003r0
March 2009
Issues with the scope of OBSS solution?
Length (OBSS graph) <= 2 is insufficient?
2.4GHz band has only 3 channels and suffers in OBSS environment. It is not in the scope of TGaa OBSS solution
If the number of channels is > 17, a length of greater than 2 is improbable
A length of 7 or 8 is common in dense deployments if the number of available channels is limited 9 or 11. This condition could be mitigated by having the QAPs fall back from 40MHz to 20MHz channels. Should TGaa specify a mechanism for this?
Is a mechanism/solution that only addresses the scope as defined acceptable (despite the fact that consistent performance will not be met) as an incremental step over legacy?
If a length of 7 or 8 is accepted to be the scope of the solution, it is not any simpler than the general OBSS problem (which is considered NP-Hard)
Slide 4
Ganesh Venkatesan, Intel Corporation
Page 4
Alex Ashley, NDS Ltd
Peter Ecclesine, Cisco Systems

5. September 2008
November 2007
doc.: IEEE /2752r1
doc.: IEEE /1003r0
March 2009
References
<OBSS related presentations to be listed here>
Slide 5
Ganesh Venkatesan, Intel Corporation
Page 5
Alex Ashley, NDS Ltd
Peter Ecclesine, Cisco Systems