1. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 1 Date: 2007-3-12 Handling of Associated Legacy Stations Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Authors:

2. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 2 Abstract This presentation provides further discussions and simulations results on the schemes we proposed in [3] to handle legacy stations associated MAPs in WLAN mesh in a scalable manner. The proposed schemes provide resolutions for the following CIDs in [2]: 756, 3649, 4605, 4606, 4607, 4385, 4866, 5697, 5698, 5699, 5701, 5702, 5703.

3. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 3 802.11s Path Selection Protocol Path selection protocol must be implemented on all MPs/MAPs to ensure baseline interoperability for communications between 802.11s MPs/MAPs and 802.11s MPs/MAPs. legacy STAs and legacy STAs. legacy STAs and 802.11s MPs/MAPs. In current 802.11s 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.

4. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 4 MAP Table MAP STA Table The problem of huge proxy tables at MAPs + + + + + As illustrated in the following example, the size of STA association tables could be much bigger than that of forwarding tables at MAPs. Hence the need of scalable, low-overhead STA handling schemes.

5. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 5 HWMP

6. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 6 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 provide resolutions for CIDs 756, 4385, 4866 in [2].

7. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 7 Assuming piggybacking of the addresses of associated stations in RREP messages, we propose a Tree-based Station Discovery Scheme, which allows the root MP to collect the association information from all MAPs. Tree-Based Station Discovery Scheme is similar to the Centralized Station Discovery Scheme described in [3]. Tree-based Station Discovery Scheme

8. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 8 Root X 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 Periodically, the Root MP broadcasts a RANN message. RANN message Broadcasting the RANN message from the Root

9. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 9 Root X 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 MAP-16 generates a RREP message containing the address of the associated legacy STA and sends it to the Root MP. The Root MP constructs the proxy table based on the RREP messages from all MAPs. RREP message Unicasting the RREP message to the Root

10. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 10 Root 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 MP. X 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 Data message When S1 wants to communicate with S2 (1/2)

11. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 11 Root Upon receiving the data messages from MAP-15, the Root MP, which knows the MAP-16 is associating S2, redirects the data message to the MAP-16. Upon receiving the data message from the Root MP, the MAP-16 sends the data message to S2. X 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 Data message When S1 wants to communicate with S2 (2/2)

12. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 12 Fast Handoff Scheme In order to mitigate the degradation of STA movement, the most up-to-dated associated stations information is quickly shared among one-hop neighbor MAPs only.

13. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 13 S2 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 When a station S2 leaves MAP-10 and moves to MAP-16, S2 is re- associated by MAP-16. S1 When S2 moves from MAP-10 to MAP-16 Root X 0

14. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 14 S2 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 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. S1 Root X 0 When S2 moves from MAP-10 to MAP-16

15. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 15 S2 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 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). S1 Root X 0 When S1 wants to communicate with S2 (1/2)

16. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 16 S2 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 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. S1 Root X 0 When S1 wants to communicate with S2 (2/2)

17. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 17 Simulation area250 m × 250 m (office) Number of MPPs1 Number of MAPs31 Number of legacy stations100 MPP LegacyStation MAP HWMP: Simulation Model

18. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 18 HWMP Routing Protocol RREP pre-defined time1 s RANN broadcast interval3 s Route table expiration time9 s TTL255 Network simulatorOPNET 11.5 Physical characteristicIEEE 802.11a OFDM MAC protocolCSMA/CA Propagation modelTwo-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 time200 s Transmission rate54 Mbps Transmit power100 mW Queue size50 packets Number of channels1 Traffic Model for VoIP CodecG.711a Voice rate64 kbps (50 pkts/s) Packet payload size160 bytes Number of traffic flows10, 20, 30, 40, 50, 60 HWMP: Simulation Parameters

19. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 19 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. HWMP: Packet Delivery Ratio

20. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 20 Due to frequent link breaks, 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. HWMP: Average End-to-end Delay

21. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 21 Due to the increase in packet contention and the number of transmissions when the STAs are moving, the routing overhead also increases up to about 0.01% – 0.06%. HWMP: Routing Overhead

22. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 22 RA-OLSR

23. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 23 The current STA handling scheme in the RA-OLSR needs to be improved because the periodical sharing of GAB information by all MAPs may cause large communications 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 [3]) Centralized Station Discovery Scheme On-demand Station Discovery Scheme We present simulation results showing the efficiency and scalability of the proposed schemes. To provide resolutions for CIDs 3649, 4605, 4606, 4607, 5697, 5698, 5699, 5701, 5702, 5703 in [2]. Motivation

24. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 24 Assuming the periodical collecting of GAB information, we propose a Centralized Station Discovery Scheme, which allows the Root MP 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. Centralized Station Discovery Scheme

25. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 25 Root 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 Periodically, e.g., MAP-16 generates a LABA message and unicasts it to the Root. The Root MP constructs the GAB based on the LABA messages from all MAPs. LABA message Unicasting the LABA message to the Root

26. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 26 Root 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. 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 Data message When S1 wants to communicate with S2 (1/3)

27. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 27 Root Upon receiving the data messages from MAP-15, the Root MP, which already knows the MAP-16 is associating S2, redirects the data message to the MAP-16. Upon receiving the data message from the Root MP, the MAP-16 sends the data message to S2. 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 Data message When S1 wants to communicate with S2 (2/3)

28. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 28 Root To perform a centralized station discovery scheme, the Root MP 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 MP, the MAP-15 sends the S1’s data message to MAP-16 along the route, which is maintained by the OLSR’s normal functions. 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 S2 S1 address set of S2 and MAP-16 Data message When S1 wants to communicate with S2 (3/3)

29. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 29 Assuming no periodical sharing of GAB information, 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. On-demand Station Discovery Scheme

30. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 30 S2 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 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. S1 Broadcast ABAR message When S1 wants to communicate with S2 (1/3)

31. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 31 S2 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 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. S1 LABA message When S1 wants to communicate with S2 (2/3)

32. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 32 S2 5 7 6 2 4 1 0 21 14 8 13 11 10 16 19 17 22 18 15 3 9 20 12 23 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. S1 Data message When S1 wants to communicate with S2 (3/3)

33. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 33 RA-OLSR Routing Protocol HELLO broadcast interval2 s TC broadcast interval5 s LABA/LABCA interval5 s Neighbor hold time6 s TC hold time15 s GAB hold time15 s Network simulatorQualNet 3.9.5 Physical characteristicIEEE 802.11b MAC protocolCSMA/CA Propagation model 3.5 exponential (received SNR = 25 dB at 100m) Network coverage area500 m × 500 m Number of MAPs25 Location of MAPsgrid (interval 100m) Number of STAs100 Location of STAsrandom Mobility of STAs static random waypoint (max 3m/s, pause time 10s ) Transmission rate 11Mbps (unicast) 11Mbps (broadcast) General Simulation time100 s Traffic Model ApplicationCBR Data rate5.12 kbps (10 pkts/s) Packet payload size512 bytes RA-OLSR: Simulation Parameters

34. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 34 Overhead can be reduced drastically by on-demand scheme. RA-OLSR: Association Overhead

35. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 35 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.

36. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 36 [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. RA-OLSR: Latency

37. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 37 Conclusions We have shown the simulation results of the proposed station discovery schemes to solve the problem of huge proxy tables. Tree-based station discovery scheme for HWMP with 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.

38. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 38 1.IEEE P802.11s Draft D1.00 2.Comments Resolution of IEEE P802.11s, 11-07/0023r19 3.Scalable Station Association Information Handling, 11-06/1842r4 References

39. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 39 Backup

40. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 40 HWMP: Packet Delivery Ratio w/o Fast Handoff When no. of traffic flows is 50, × staticabout 56.0% mobileabout 10.2% When no. of traffic flows is 150, × staticabout 18.5% mobileabout 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.

41. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 41 HWMP: Data Throughput w/o Fast Handoff When no. of traffic flows is 50, × static 1.65 Mbps mobile0.41 Mbps When no. of traffic flows is 150, × static2.11 Mbps mobile0.45 Mbps When the legacy STAs are moving, many links of legacy STA are broken, which lead to the low data throughput.

42. Submission doc.: IEEE 802.11-07/0318r3March 2007 Hiraku Okada, et.al.Slide 42 HWMP: Routing Overhead w/o Fast Handoff When no. of traffic flows is 50, × staticabout 0.04% mobileabout 0.31% When no. of traffic flows is 150, × staticabout 0.05% mobileabout 0.22% The routing overhead is about 4 times when the legacy STAs are stationary more than when the legacy STAs are moving.