1. Handling of Associated Legacy Stations
March 2007
doc.: IEEE /0318r1
March 2007
Handling of Associated Legacy Stations
Date:
Authors:
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Hiraku Okada, et.al.
Hiraku Okada, et.al.

2. March 2007
doc.: IEEE /0318r1
March 2007
Abstract
In this presentation, we address the problem of a huge proxy table for all MAPs that associating legacy stations
We proposed schemes how to handle the legacy stations in the s Mesh WLAN. (Scalable Station Association Information Handling, 11-06/1842r4)
We present some simulation results in regards to our proposed schemes.
To solve the CID 756, 3649, 4605, 4606, 4607, 4385, 4866, 5697, 5698, 5699, 5701, 5702, 5703 of comment resolution (07/0023r19)
Hiraku Okada, et.al.
Hiraku Okada, et.al.

3. 802.11s Path Selection Protocol
March 2007
802.11s Path Selection Protocol
Path selection protocol must be implemented on all MPs/MAPs to ensure baseline interoperability for
802.11s MPs/MAPs and s MPs/MAPs.
legacy STAs and legacy STAs.
legacy STAs and s MPs/MAPs.
In current s specification, two path selection protocols are defined.
Hybrid Wireless Mesh Protocol (HWMP) – default protocol.
Radio-aware OLSR (RA-OLSR) – optional protocol.
HWMP: So far, no Station Association Discovery Scheme to handle the legacy STAs.
RA-OLSR: LAB/GAB Scheme is applied to handle the legacy STAs.
Does this interoperability work???
Hiraku Okada, et.al.

4. The problem of a huge proxy table for all MAPs
March 2007
The problem of a huge proxy table for all MAPs
Since STA table will become huge, a low-overhead legacy station handling scheme has to be developed. +
MAP
Table
STA
Table
MAP
STA
Hiraku Okada, et.al.

5. March 2007
HWMP
Hiraku Okada, et.al.

6. March 2007
Motivation
In HWMP, there is no description (text) about station legacy association handling scheme.
However, a proactive tree mode of HWMP protocol enables MAPs to handle legacy stations.
We show simulation results of legacy station handling scheme for HWMP.
To solve the CID 756, 4385, 4866 of comment resolution (07/0023r19)
Hiraku Okada, et.al.

7. Tree-based Station Discovery Scheme
March 2007
Tree-based Station Discovery Scheme
By assuming the piggybacking of associated stations’ addresses in RREP message is configured, we propose a Tree-based Station Discovery Scheme, which allows the root to collect the association information from all MAPs.
Tree-Based Station Discovery Scheme is similar to the Centralized Station Discovery Scheme (11-06/1842r4).
Hiraku Okada, et.al.

8. Broadcasting the RANN message from the Root
March 2007
doc.: IEEE /0318r1
March 2007
Broadcasting the RANN message from the Root
Periodically, the Root broadcasts a RANN message.
Root X 1 3 2 5 9 4 7 6 8 12 11
RANN
message 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

9. Unicasting the RREP message to the Root
March 2007
doc.: IEEE /0318r1
March 2007
Unicasting the RREP message to the Root
MAP-16 generates a RREP message containing the associated legacy STA’s address and sends it to the Root.
Root constructs the proxy table based on the RREP messages from all MAPs.
Root X 1 3 2 5 9 4 7 6 8 12 11
RREP
message 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

10. When S1 wants to communicate with S2 (1/2)
March 2007
doc.: IEEE /0318r1
March 2007
When S1 wants to communicate with S2 (1/2)
When a source station S1 wants to communicate with a destination station S2, S1 sends its data message to MAP-15.
Upon receiving the data message from S1, MAP-15 forwards it to the Root.
Root X 1 3 2 5 9 4
Data message 7 6 8 12 11 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

11. When S1 wants to communicate with S2 (2/2)
March 2007
doc.: IEEE /0318r1
March 2007
When S1 wants to communicate with S2 (2/2)
Upon receiving the data messages from MAP-15, the Root that is knowing the MAP-16 is associating S2 redirects the data message to the MAP-16.
Upon receiving the data message from the Root, the MAP-16 sends the data message to S2.
Root X 1 3 2 5 9 4 7 6
Data message 8 12 11 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

12. March 2007
Fast Handoff Scheme
In order to mitigate the degradation of STA movement, the most up-to-dated associated stations information is quickly shared among MAPs.
Hiraku Okada, et.al.

13. When S2 moves from MAP-10 to MAP-16
March 2007
When S2 moves from MAP-10 to MAP-16
When a station S2 leaves MAP-10 and moves to MAP-16, S2 is re-associated by MAP-16.
Root X 1 3 2 5 9 4 7 6 8 12 11 S2 10 15 14 13 16 S2 17 18 S1 21 19 23 22 20
Hiraku Okada, et.al.

14. When S2 moves from MAP-10 to MAP-16
March 2007
When S2 moves from MAP-10 to MAP-16
When a station S2 leaves MAP-10 and moves to MAP-16, S2 is re-associated by MAP-16.
MAP-16 broadcasts its new joined STA S2 information using HELLO message to its one-hop neighbor MAPs only.
Root X 1 3 2 5 9 4 7 6 8 12 11 S2 10 15 14 13 16 S2 17 18 S1 21 19 23 22 20
Hiraku Okada, et.al.

15. When S1 wants to communicate with S2 (1/2)
March 2007
When S1 wants to communicate with S2 (1/2)
When a station S1 wants to communicate with S2, S1 sends its data messages to MAP-15 that associating S1. Upon receiving the data message from S1, MAP-15 transforms the header of the data messages to the header containing 6-address scheme and directs the data messages to MAP-10 (without knowing that S2 moved).
Root X 1 3 2 5 9 4 7 6 8 12 11 S2 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.

16. When S1 wants to communicate with S2 (2/2)
March 2007
When S1 wants to communicate with S2 (2/2)
Upon receiving the data messages from MAP-15, MAP-10 redirects the data messages to MAP-16 that is currently associating S2. Then, MAP-16 sends the data messages to S2.
Root X 1 3 2 5 9 4 7 6 8 12 11 S2 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.

17. HWMP: Simulation Model
March 2007
HWMP: Simulation Model
MPP
Legacy
Station
MAP
Simulation area
250 m × 250 m (office)
Number of MPPs 1
Number of MAPs 31
Number of legacy stations
100
Hiraku Okada, et.al.

18. HWMP: Simulation Parameters
March 2007
doc.: IEEE /0318r1
March 2007
HWMP: Simulation Parameters
Network simulator
OPNET 11.5
Physical characteristic
IEEE a OFDM
MAC protocol
CSMA/CA
Propagation model
Two-ray
Mobility model
Random Walk
Node speed is in range of [0, 1 m/s]
Node direction is random
Pause time is in range of [0, 10 s]
Simulation time
200 s
Transmission rate
54 Mbps
Transmit power
100 mW
Queue size
50 packets
Number of channels 1
HWMP Routing Protocol
RREP pre-defined time
1 s
RANN broadcast interval
3 s
Route table expiration time
9 s
TTL
255
Traffic Model for VoIP
Codec
G.711a
Voice rate
64 kbps (50 pkts/s)
Packet payload size
160 bytes
Number of traffic flows
10, 20, 30, 40, 50, 60
Hiraku Okada, et.al.
Hiraku Okada, et.al.

19. HWMP: Packet Delivery Ratio
March 2007
HWMP: Packet Delivery Ratio
Due to STA mobility, leads to frequent link broken, the STAs are moving gain lower PDR than the STAs are static.
3.9% – 8.9% packet drops when the STAs are moving.
Hiraku Okada, et.al.

20. HWMP: Average End-to-end Delay
March 2007
HWMP: Average End-to-end Delay
Due to frequent link broken, resulting in an increasing packet contention and number of transmission, which leads to the STAs are moving yields larger delay than the STAs are static.
0.7% – 1.2% delay increases when the STAs are moving.
Hiraku Okada, et.al.

21. HWMP: Routing Overhead
March 2007
HWMP: Routing Overhead
Due to the increasing in packet contention and number of transmission when the STAs are moving, the routing overhead also increases up to about 0.01% – 0.06%.
Hiraku Okada, et.al.

22. March 2007
RA-OLSR
Hiraku Okada, et.al.

23. March 2007
Motivation
In RA-OLSR, even though there is a handling scheme, it still need to be improved because periodical sharing of GAB information by all the MAPs will generate a large communication overhead.
We proposed low-overhead station discovery schemes to solve the problem of a huge proxy table in each MAP. (Scalable Station Association Information Handling, 11-06/1842r4)
Centralized Station Discovery Scheme
On-demand Station Discovery Scheme
We present some simulation results in regards to our proposed schemes.
To solve the CID 3649, 4605, 4606, 4607, 5697, 5698, 5699, 5701, 5702, 5703 of comment resolution (07/0023r19)
Hiraku Okada, et.al.

24. Centralized Station Discovery Scheme
March 2007
Centralized Station Discovery Scheme
By assuming the periodical collecting GAB information is configured, we propose a Centralized Station Discovery Scheme, which allows the Root to collect the LABA messages from all MAPs and provide the required entry of the proxy table to MPs/MAPs.
Centralized Station Discovery Scheme is similar to the Tree-Based Station Discovery Scheme except for direct data forwarding between MAPs.
Hiraku Okada, et.al.

25. Unicasting the LABA message to the Root
March 2007
doc.: IEEE /0318r1
March 2007
Unicasting the LABA message to the Root
Periodically, e.g., MAP-16 generates a LABA message and unicasts it to the Root.
Root constructs the GAB based on the LABA messages from all MAPs.
Root 1 3 2 5 9 4 7 6 8 12 11
LABA
message 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

26. When S1 wants to communicate with S2 (1/3)
March 2007
doc.: IEEE /0318r1
March 2007
When S1 wants to communicate with S2 (1/3)
When a source station S1 wants to communicate with a destination station S2, S1 sends its data message to MAP-15.
Upon receiving the data message from S1, MAP-15 forwards it to the Root.
Root 1 3 2 5 9 4
Data message 7 6 8 12 11 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

27. When S1 wants to communicate with S2 (2/3)
March 2007
doc.: IEEE /0318r1
March 2007
When S1 wants to communicate with S2 (2/3)
Upon receiving the data messages from MAP-15, the Root that is knowing the MAP-16 is associating S2 redirects the data message to the MAP-16.
Upon receiving the data message from the Root, the MAP-16 sends the data message to S2.
Root 1 3 2 5 9 4 7 6
Data message 8 12 11 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

28. When S1 wants to communicate with S2 (3/3)
March 2007
doc.: IEEE /0318r1
March 2007
When S1 wants to communicate with S2 (3/3)
To perform a centralized station discovery scheme, the Root informs the MAP-15 of address set, which contain the address of S2 that is corresponding to the address of MAP-16.
Upon receiving the address set message from the Root, the MAP-15 sends the S1’s data message to MAP-16 along the route, which is maintained by the OLSR’s normal functions.
Root 1 3 2
address set of S2 and MAP-16 5 9 4 7 6 8 12 11 10 15
Data message 14 13 16 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.
Hiraku Okada, et.al.

29. On-demand Station Discovery Scheme
March 2007
On-demand Station Discovery Scheme
By assuming the periodical sharing GAB information is not configured, we propose an On-demand Station Discovery Scheme, which allows a MAP to broadcast an Association Base Address Request (ABAR) message to discover a station and also allows a MAP to unicast a LABA message to inform the discovered station information.
Upon receiving the LABA message, the MAP treats the LABA message as an entry of discovered station in its proxy table.
This proxy table indirectly takes the role of GAB.
Hiraku Okada, et.al.

30. When S1 wants to communicate with S2 (1/3) Broadcast ABAR message
March 2007
When S1 wants to communicate with S2 (1/3)
When a source station S1 wants to send a data to a destination station S2, first S1 sends it to MAP-15.
When the MAP-15 has no entry in its own proxy table, MAP-15 broadcasts an ABAR message to request for the address of S2. 1 3
Broadcast ABAR message 2 5 9 4 7 6 8 12 11 10 15 14 13 16 S2 17 18 S1 21 19 23 22 20
Hiraku Okada, et.al.

31. When S1 wants to communicate with S2 (2/3)
March 2007
When S1 wants to communicate with S2 (2/3)
Upon receiving the ABAR message, the MAP-16 unicasts a LABA message, which contains a “address set.”
In this address set, it contains the address of S2 that is corresponding to the address of the MAP originator. 1 3 2 5 9 4 7 6 8 12 11 10 15 14
LABA message 13 16 S2 17 18 S1 21 19 23 22 20
Hiraku Okada, et.al.

32. When S1 wants to communicate with S2 (3/3)
March 2007
When S1 wants to communicate with S2 (3/3)
Upon receiving the LABA message, the MAPs along the route (e.g., MAP-13, MAP-14, MAP-17) and also MAP-15 insert the LABA message as an entry of S2 in its proxy table.
This proxy table indirectly takes the role of GAB.
At last, the MAP-15 sends the S1’s data to S2 via the route between MAP-15 and MAP-16. 1 3 2 5 9 4 7 6 8 12 11 10 15 14 13 16
Data message 17 18 S1 21 S2 19 23 22 20
Hiraku Okada, et.al.

33. RA-OLSR: Simulation Parameters
March 2007
doc.: IEEE /0318r1
March 2007
RA-OLSR: Simulation Parameters
Network simulator
QualNet 3.9.5
Physical characteristic
IEEE b
MAC protocol
CSMA/CA
Propagation model
3.5 exponential (received SNR = 25 dB at 100m)
Network coverage area
500 m × 500 m
Number of MAPs 25
Location of MAPs
grid (interval 100m)
Number of STAs
100
Location of STAs
random
Mobility of STAs
static
random waypoint (max 3m/s, pause time 10s )
Transmission rate
11Mbps (unicast)
11Mbps (broadcast)
RA-OLSR Routing Protocol
HELLO broadcast interval
2 s
TC broadcast interval
5 s
LABA/LABCA interval
Neighbor hold time
6 s
TC hold time
15 s
GAB hold time
General
Simulation time
100 s
Traffic Model
Application
CBR
Data rate
5.12 kbps (10 pkts/s)
Packet payload size
512 bytes
Hiraku Okada, et.al.
Hiraku Okada, et.al.

34. RA-OLSR: Association Overhead
March 2007
RA-OLSR: Association Overhead
Overhead can be reduced drastically by on-demand scheme.
Hiraku Okada, et.al.

35. RA-OLSR: Packet Delivery Ratio
March 2007
RA-OLSR: Packet Delivery Ratio
[static] PDR of proposed schemes is almost the same with conventional scheme.
[3 m/s] PDR is degraded because of disappearance of selected path.
Hiraku Okada, et.al.

36. RA-OLSR: Latency [static] Latency of on-demand scheme is bad.
March 2007
RA-OLSR: Latency
[static] Latency of on-demand scheme is bad.
[3 m/s] Latency of on-demand scheme becomes worse but slightly better than that of centralized scheme.
Hiraku Okada, et.al.

37. March 2007
Conclusions
We have shown the simulation results of the proposed station discovery schemes to solve the problem of huge proxy table.
Tree-based station discovery scheme for HWMP Fast handoff scheme
Centralized station discovery scheme for RA-OLSR
On-demand station discovery scheme for RA-OLSR
*It could be improved by the fast handoff scheme.
Notes: On-demand station discovery scheme could be applied to HWMP.
Hiraku Okada, et.al.

38. References IEEE P802.11s Draft D1.00
March 2007
References
IEEE P802.11s Draft D1.00
Comments Resolution of IEEE P802.11s, 11-07/0023r19
Scalable Station Association Information Handling, /1842r4
Hiraku Okada, et.al.

39. March 2007
Backup
Hiraku Okada, et.al.

40. HWMP: Packet Delivery Ratio w/o Fast Handoff
March 2007
HWMP: Packet Delivery Ratio w/o Fast Handoff
When no. of traffic flows is 50,
static about 56.0%
mobile about 10.2%
When no. of traffic flows is 150,
static about 18.5%
mobile about 5.8%
The packet delivery ratio is about 3~5 times when the legacy STAs are stationary more than when the legacy STAs are moving.
Hiraku Okada, et.al.

41. HWMP: Data Throughput w/o Fast Handoff
March 2007
HWMP: Data Throughput w/o Fast Handoff
When no. of traffic flows is 50,
static Mbps
mobile 0.41 Mbps
When no. of traffic flows is 150,
static 2.11 Mbps
mobile 0.45 Mbps
When the legacy STAs are moving, many links of legacy STA are broken, which lead to the low data throughput.
Hiraku Okada, et.al.

42. HWMP: Routing Overhead w/o Fast Handoff
March 2007
HWMP: Routing Overhead w/o Fast Handoff
When no. of traffic flows is 50,
static about 0.04%
mobile about 0.31%
When no. of traffic flows is 150,
static about 0.05%
mobile about 0.22%
The routing overhead is about 4 times when the legacy STAs are stationary more than when the legacy STAs are moving.
Hiraku Okada, et.al.