1. Media Protection Enhancement to Improve Efficiency for Mesh
doc.: IEEE /xxxxr0
May 2005
May 2005
Media Protection Enhancement to Improve Efficiency for Mesh
Date:
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Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

2. doc.: IEEE /xxxxr0
May 2005
May 2005
Abstract
Brief Summary of “Short NAV” : Efficient Media Protection for Mesh
New challenges in Media Protection for Mesh is described
Problem with current Media Protection Protocol is explained
Proposal for an Enhancement in Media Protection : “Short NAV”
Simulation results are presented to show the effect of “Short NAV” in Mesh-like network topology
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

3. Brief Summary of “Short NAV” : Media Protection for Mesh
doc.: IEEE /xxxxr0
May 2005
May 2005
Brief Summary of “Short NAV” : Media Protection for Mesh
Short NAV
Short NAV is an efficient Media Protection protocol suited for Mesh
The Network Allocation Vector (NAV) for Virtual Carrier Sense is shortened to protect only for the response packet
NAV in RTS protects CTS
NAV in CTS protects DATA
NAV in DATA protects ACK
Why is this effective towards Mesh? Continued…
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

4. New Challenges in Media Protection for Mesh
doc.: IEEE /xxxxr0
May 2005
May 2005
New Challenges in Media Protection for Mesh
Varying Channel Condition
Hidden Node Problem
Various new challenges are posed for Mesh Networking
Extensive Hidden Nodes are expected in Mesh, unlike typical AP-MT Network
Far more variance will be seen in channel condition due to mobility
Current RTS/CTS procedure is incompatible with these Problems!
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

5. Problem with Current Media Protection
doc.: IEEE /xxxxr0
May 2005
Problem with Current Media Protection
May 2005
Current Media Protection Protocol
Current Media Protection is inefficient in Hidden Node Environment
When RTS/CTS handshake fail, the media can be wasted until the end of NAV
Current Media Protection is incompatible with fast varying channel
With Current RTS/CTS handshake, the Rate of DATA needs to be pre-determined
Short NAV solves these issues!!
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

6. “Short NAV” for Efficient Mesh
doc.: IEEE /xxxxr0
May 2005
May 2005
“Short NAV” for Efficient Mesh
Short NAV
Short NAV is efficient in Hidden Node Environment
Even when RTS/CTS handshake fail, wasted media time is minimized
Short NAV is compatible with fast varying channel
The Data Rate can be determined by the receiver, allowing fast adaptation to varying channel
Short NAV is efficient for Mesh
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

7. Simulation Model : Mesh Topology Network
doc.: IEEE /xxxxr0
May 2005
May 2005
Simulation Model : Mesh Topology Network
Simulation to see the effect of Short NAV compared with Conventional NAV
Simulation Model
30 Stations are randomly allocated in a 100[m] sequare
41 Links are randomly assigned
Offered load of each link in 10[Mbps]
TGn PHY Parameters
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

8. Simulation Results : Mesh Topology Network
doc.: IEEE /xxxxr0
May 2005
Simulation Results : Mesh Topology Network
May 2005
24+[%] UP!
Large increase in System Throughput can be seen with Short NAV
More than 24[%] throughput increase
Enhancement of Media Protection will be essential for Efficient Mesh
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

9. doc.: IEEE /xxxxr0
May 2005
May 2005
Conclusion
Brief Summary of “Short NAV” : Efficient Media Protection for Mesh
New challenges in Media Protection for Mesh were described
Problem with current Media Protection Protocol was explained
Proposal for an Enhancement in Media Protection : “Short NAV”
Simulation results were presented to show the effect of “Short NAV” in Mesh-like network topology
Enhancement of Media Protection will be essential for Efficient Mesh
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

10. References May 2005 doc.: IEEE 802.11-05/xxxxr0 May 2005
Yuichi Morioka, Sony Corporation
Yuichi Morioka, Sony Corporation

11. Appendix: Residential Model (OBSS)
May 2005
Appendix: Residential Model (OBSS)
2 Cell Environment
60[m]
Multiple Coinciding Residents
Typical residential networks are expected to coincide
Especially with channel bonding this problem will surface
The effect of OBSS is currently out of scope of TGn, but must be dealt with
The “Residential” model defined in IEEE TGn is exactly preserved
To imitate BSS isolation the distance between the APs are set to 60[m]
Yuichi Morioka, Sony Corporation

12. Appendix: Throughput Results of OBSS
May 2005
Appendix: Throughput Results of OBSS
# of BSSs
Configuration
Standard NAV
Short NAV
Difference
1 Cell
[Mbps]
[Mbps]
11.2 [%]
2 Cell
[Mbps]
[Mbps]
17.5 [%]
3 Cell
[Mbps]
[Mbps]
20.1 [%]
4 Cell
[Mbps]
[Mbps]
29.0 [%]
With a single BSS, the effect of Short NAV is 11.2[%]
As the number of BSSs increase, the difference increase
BSSs are configured in a side-by-side fashion
With 4 BSSs coinciding, the difference between conventional NAV protection and Short NAV is up to 29[%]
Note:
In the above simulation results duration value is carried in the PHY Header
Yuichi Morioka, Sony Corporation