1. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 1 Proactive Mesh Networks (ProM) Date: 2005-05-13 Authors: 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 NameCompanyAddressPhoneE-mail Bing ZhangNational Institute of Information and Communications Technology 3-5 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan +81-774-98-6820zhang@nict.go.jp Oyunchimeg ShagdarATR Adaptive Communication Research Laboratories 2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan +81-774-95-1501oyunaa@atr.jp Suhua TangATR Adaptive Communication Research Laboratories 2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan +81-774-95-1544shtang@atr.jp Youiti KadoOki Electric Industry Co., Ltd.2-5-7 Honmachi, Chuo-ku, Osaka, Japan +81-6-6260-0700kado567@oki.com Masanori NozakiOki Electric Industry Co., Ltd.2-5-7 Honmachi, Chuo-ku, Osaka, Japan +81-6-6260-0700nozaki765@oki.com

2. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 2 Outline A proactive layer-2 routing protocol –Accommodating legacy STA associated with Mesh AP –Topology discovery –WDS unicast/broadcast QoS support –Load balancing mechanism –Delay based priority control Multiple radios with distributed channel assignment Conclusion

3. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 3 Proactive Routing Protocol for Mesh Networks

4. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 4 Architecture - Network Model - Router Server Mesh Portal Mesh AP Legacy STA ・・・ 802.11a(5.2GHz) ・・・ 802.11b/g(2.4GHz) ・・・ 802.11a(5.2GHz) Connecting Mesh Points based on proactive protocol Efficiently accommodating Legacy STA associated with Mesh AP MP: Mesh Point Legacy STA MP

5. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 5 Local Topology Discovery - Hello Message Exchange - Periodically exchanging Hello message –Advertising 1-hop neighbor information Upon receiving the Hello message from neighbors –Checking the link status with 1-hop neighbors –Acquiring the 2-hop neighbor information MP-A adds MP list from MP-B that is not included in its 1-hop MP list, into 2-hop MP list. MP-AMP-B DA MAC:FF SA MAC:A FCDuFCS 1-hop Neighbor MAC Address list DA MAC:FF SA MAC:B FCDu FCS 1-hop Neighbor MAC Address list MP-B adds MP list from MP-A that is not included in its 1-hop MP list, into 2-hop MP list. Hello frame from MP-A Hello frame from MP-B FCDuFCSRADataTASADA WDS Frame RA: Receiver Address TA: Transmitter Address DA: Destination Address SA: Source Address

6. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 6 Local Topology Discovery - MPR Selection - MP determines the OLSR-based MPR (Multipoint Relay) set from its 1-hop neighbors. MP advertises its MPR information in the periodic HELLO messages. MP-A 1-hop neighbor MPR of MP-A 2-hop neighbor

7. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 7 Topology Discovery - ASAT & TC Messages - Mesh AP generates an ASAT (Associated Station Address Table) message which records a MAC address table of legacy STA associated with it. MP generates a TC (Topology Control) message which includes the links to all MPs of its MPR selector set. ASAT Leagacy STAs ASAT Leagacy STAs Mesh AP-AMesh AP-C MP-B TC

8. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 8 Topology Discovery - ASAT & TC Message Forwarding - MPR forwards the ASAT & TC messages from its MPR selectors. Flooding ASAT & TC messages in the network to construct the routes to all of MPs and legacy STAs MP-A DA MAC:FF SA MAC:A FCDuFCS MP-C DA MAC:FF SA MAC:B FCDuFCS MP-A broadcasts the TC frames (1) MP-B retransmitted the TC frame by replacing SA with MAC:B (2) advertised link set advertised link set TC frame from MP-A TC frame from MP-B Mesh AP-A MP-B (MPR) DA MAC:FF SA MAC:A FCDuFCS ASAT SN, MAC:A MP-C DA MAC:FF SA MAC:B FCDuFCS ASAT SN, MAC:A ASAT frame from Mesh AP-A ASAT frame from Mesh MP-B Mesh AP-A broadcasts the ASAT frames (1) MP-B retransmitted the ASAT frame by replacing SA with MAC:B (2) MP-B (MPR)

9. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 9 Example of Unicast Routing 1.STA1 sends a data frame of infra-mode to Mesh-AP1. 2.Mesh-AP1 –learn STA2’s association to Mesh-AP3 from its ASAT. –transform STA1’s data frame into a WDS frame. –send the WDS frame to Mesh-AP2. (RA : Mesh-AP2, TA : Mesh-AP1, SA : STA1, DA : STA2) 3.Mesh-AP2 –learn STA2’s association to Mesh-AP3 from its ASAT. –forward the WDS frame to Mesh-AP3.( RA : Mesh-AP3, TA : Mesh-AP2, SA : STA1, DA : STA2) 4.Mesh-AP3 –de-transform the WDS frame into the data frame of infra-mode. –forward the data frame to STA2. STA1 Mesh-AP1Mesh-AP2Mesh-AP3 STA2 (1) (2)(3) (4)

10. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 10 Example of Broadcast Routing STA1 Mesh-AP1Mesh-AP2Mesh-AP3 STA4 (1) (2)(3) (4) STA2STA3 (2)(4) 1.STA1 sends a data frame to Mesh-AP1. ( DA : broadcast address) 2.Mesh-AP1 – transform STA1’s data frame into a WDS frame. – broadcast the WDS frame to Mesh-APs. (RA : broadcast address, TA : Mesh-AP1, SA : STA1, DA : broadcast address) – broadcast the data frame to the associated STAs. 3.MPR Mesh-APs broadcast the WDS frame. (RA : broadcast address, TA : own address, SA : STA1, DA : broadcast address) 4.Mesh-APs –de-transform the WDS frame into the original data frame. –broadcast to the associated STAs.

11. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 11 Supporting multi-path routing for load balancing –Every flow tends to choose the same minimum hop route. As a result, some MPs are heavily loaded. –Introducing a flow based multi-path routing to distribute the traffic over the whole networks. Supporting delay based priority control –Many applications (Voice, Video, etc.) are delay sensitive. –Introducing an end-to-end delay based priority control scheme to reduce the Maximum delay for real time traffics. QoS Support

12. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 12 Load Balancing - Problem Specification - Why load balancing using multiple paths is required –MPs usually use only a path to each destination. –Traffics to the same destination run down into a single path. –It is desirable to balance the load using multiple paths. 13275046 p2 p1 89 heavy Path Index DARA p173 p274 Routing Table with Multiple Paths

13. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 13 Load Balancing - Related Schemes - Existing Scheduling Schemes –MPs randomly select an RA (= next-hop MP) for each packet destined to the same DA. 1327504689 Path Index DARA p173 p274 Routing Table with Multiple Paths Merit –Easy to implement. Demerit –It causes out-of-order frame delivery.

14. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 14 Load Balancing - Pseudo Flow Based Scheme - Pseudo flow : –Type 1 : Identified by DA and SA –Type 2 : Identified by DA and TA (= previous-hop MP) MPs generate a pseudo flow table. MPs determine next-hop MP for each pseudo flow based on the current load condition. 13275046 f2 f1 f2 89 Flow Index DASARA f1783 f2794 Pseudo Flow Table [type 1] Flow Index DATARA f1713 f2724 Pseudo Flow Table [type 2] Merits –Utilizing WDS header Info. –A pseudo flow’s path is stable. –In-order frame delivery. Demerit –Cross grained.

15. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 15 Delay Based Priority Control - Problem Specification - Existing QoS schemes : the same traffic class (ex. Voice) = the same priority End-to-end delay increases with number of hops, congestion and so on! Delay based priority control scheme should be considered! 146532 Small number of hops: Allowed delay: 50ms; Actual delay: 20ms Small number of hops: packets reach their destinations with time to spare Large number of hops: packet might not be able to meet the delay requirement Large number of hops : Allowed delay: 50ms Actual delay: 80ms 1 6, Allowed delay: 50ms 2 3, Allowed delay: 50ms

16. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 16 Intermediate nodes dynamically prioritize packets based on their delay requirement and the actual delay characteristics. the same traffic class the same delay requirement the actual delay varies with the number of hops and congestion. Prioritizing mechanism based on –number of hops –time stamp –congestion at intermediate nodes Delay based Priority Control - Proposed Schemes -

17. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 17 Intermediate MPs prioritize packets based on number of hops –Number of hops is learnt from the routing table. –Larger number of hops : higher priority Forward packets based on their priority level 146532 Routing table DestNumber of hops 31 63 Delay based Priority Control - Prioritizing mechanism based on number of hops - Priority level: higher Allowed delay: 50ms Actual delay : 40ms

18. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 18 Multiple Radios - Distributed Channel Assignment (CA) - Premise –Multiple interfaces/radios, multiple channels Basic principle for CA –Least used channel first Features of proposed scheme –Minimizing co-channel interference –Auto configuration of the mesh network –Guarantee connectivity Both ends of a link share the common channel IF0 IF1 C B D A

19. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 19 Basic Steps - CA for a Single Link - Initiating Mesh-AP(A) S1: Get the common channels (send Request message) S3: Check CA condition and select the least used channel S4: Assign the channel to the link (send Reserve message) S6: Actually set the channel S7: Update channel usage and forward CA message (GlobalCA) Responding Mesh-AP(B) S2: Answer with RequestReply, containing the available channels S5: Answer with ReserveReply S6: Actually set the channel S8: Update CA sequence number and continue CA IF0 IF1 CB A D

20. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 20 Example with Distributed Channel Assignment After CA Before CA 1 3 2 610 11 13 4 5 9 7 8 14 15 12 16 1 3 610 1113 12 5 2 47 8 9 14 16 15 Mesh AP1Mesh AP2

21. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 21 CA for Newly Joined Mesh AP Procedures for New Mesh AP (Mesh-AP-17, 18) Mesh-AP-17,18 –monitor the default channel. –passively scan other channels. –select the least used channel. –send Reserve message to the desired neighbor. Neighbors respond by sending a Reply. 1 3 6 2 47 17 10 59 8 18 14 15 1612 1311 12 3 64 5 10111312 9 17718814 15 16 Mesh-AP17 and 18 newly joining After CA

22. doc.: IEEE 802.11-05/0386r2 Submission Bing Zhang, et al. May 2005 Slide 22 Conclusions A proactive routing protocol –Accommodating the legacy STA associated with Mesh AP –Optimizing the amount of link-state information –Supporting unicast and broadcast QoS support –Flow based load balancing Alleviating out-of-order frame delivery –Delay based priority control Prioritizing mechanism based on number of hops Multiple radios –Assignning the channels with a distributed scheme