1. Prioritized MAC Access Mechanism of Routing-related Frame for ESS Mesh
SK Sung, Samsung Electronics

2. Overview Introduction
MAC protocol and Ad hoc routing (MANET)
Prioritized MAC access mechanism of routing-related frame for mobile ad hoc network
Independent BSS case
ESS Mesh case
Conclusion

3. In the first…
Samsung is basically supportive for the ESS mesh network standardization efforts.
We recommend an enhanced quality of service from mesh network by adopting efficient channel access scheme considering specific feature of frame.

4. Introduction 802.11 MAC access mechanism
Contention-based and contention free strategy
Discriminatory IFS according to PCF/DCF
Prioritized access to medium through PCF
For infrastructure BSS, AP, as PC, is generally vested with the control of coordination functions
For independent BSS case, all the STAs will basically have equal access priority of DIFS, though might have random backoff procedure

5. Introduction Mobile Ad hoc Network (MANET)
MANET examples with respect to WLAN
Independent BSS, ad hoc WDS
Each node generally has a self-configuring and healing function in routing algorithm
Routing algorithm discovers dynamic topologies and decides route using link metric information
When initiating MANET routing algorithm, the exchange of MANET routing-related frame is recommended to have priority to other data traffic

6. Adhoc Routing Protocol
Prioritized channel access for routing-related information
Facilitate fast and efficient ad hoc routing
Potentially reduces packet loss via fast link setup
source
destination A B C IP
MARP Core
MAC
PHY
Application B C
MARP: Mobile Ad hoc Routing Protocol

7. Adhoc Routing Protocol
MANET frame and stack
MANET control frame
Information for routing algorithm
PHY aware metric
Routing path
MANET data frame
Lower layer data unit
Application IP 생략
MARP Core
MAC
PHY

8. Prioritized IFS scheme for MANET - IBSS
Independent BSS(IBSS)
Prioritized medium access using shorter IFS
SIFS< MCIFS (MARP control IFS) < DIFS
Guaranteed access priority than ‘Random Backoff Time’
DIFS
Next Frame
Defer Access
SIFS
MCIFS
(control frame)
(data frame)
Busy Medium
Backoff Window
Slot time
Contention Window
Select slot and decrement backoff as long as medium is idle
No functional entity playing as PC
Backoff procedure after DIFS
Network Access Method for IBSS

9. Prioritized IFS scheme for MANET - IBSS
Access and backoff procedure
Data Frame
Station A
DIFS
Defer
Defer
Station B
MANET data frame
MCIFS
Defer
Station C
MANET control frame
DIFS
DIFS
Defer
Defer
Station D
MANET data frame
Backoff procedure for IBSS

10. Prioritized IFS scheme for MANET - IBSS
Example of introducing MCIFS flag in existing MAC format
Frame
Control
Duration ID
Addr 1 2 3
Sequence
control 4
body
FCS
b b3 b b7
Protocol
Ver.
Type
Subtype To DS
From
More
Frag
Retry
PWR
Mgt
data
WEP
Order
The reserved bits in this field can be used whether the incoming frame is MANET control frame or MANET data frame
e.g) ~001110,001011~001111,101000~101111

11. Valid Type and Subtype field

12. Ad hoc WDS Hosting AP functions in ad hoc WDS
Inherit general AP functions
Constructs/Reconfigure ad hoc DS
Construction of wireless backbone network
Recommended to provide prioritized access to DCF/PCF at BSS
AP#n
Internet
AP#2
Router
AP#4
802.3D
LAN
AP#1
Bridge
AP#3

13. Prioritized IFS scheme for MANET - ad hoc WDS
Ad hoc DS formation scheme prior to normal access mechanism
Prioritized medium access using shorter IFS
Ex.1) SIFS< MCIFS = PIFS < DIFS
Ex.2) SIFS< MCIFS < PIFS < DIFS
Guaranteed access priority than ‘Random Backoff Time’

14. Prioritized IFS scheme for MANET - ad hoc WDS
Example 2
SIFS< MCIFS < PIFS
DIFS
(data frame)
Contention Window
PIFS
(data frame)
Slot time
DIFS
MCIFS
(control frame)
Busy Medium
SIFS
Backoff Window
Next Frame
Select slot and decrement backoff as long as medium is idle
Defer Access
Network Access Method for adhoc WDS

15. Pros and cons
Pros
MANET route can be constructed relatively fast due to less contention when accessing medium
Mitigates data loss due to delayed MANET routing construction
Possibly, allows faster node mobility
Cons
Required is algorithm/equipment to decide whether incoming frame is MANET control or data frame

16. Conclusion
We suggest
Prioritized medium access mechanism for routing-related frame
For both IBSS and ad hoc WDS
The MAC amendment be independent on the information that in which layer the ad hoc routing protocol exists, but recommended to be placed at lower layers(L3 or L2.5) considering latency

17. Open Issues? Again
To guarantee a precedent topology discovery/ path setup, whether SG MES will
take complete adoption of QoS-related characteristics from 11e
just simply make minor amendment from the current MAC

18. Back Up

19. Supplementary for prioritized access
Process and equipment to decide and disseminate MANET routing control frame and data frame