1. doc.: IEEE 802.11-05/0386r0 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 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 2 Outline Introducing a proactive routing protocol for mesh networks (ProM) –Accommodating legacy STA associated with Mesh AP –Topology discovery –OLSR-based L2 routing –WDS unicast/broadcast QoS support –Load balancing mechanism –Delay based priority control Multiple radios with distributed channel assignment Conclusion

3. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 3 Proactive routing protocol for mesh networks (ProM)

4. doc.: IEEE 802.11-05/0386r0 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 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 5 Local Topology Discovery - Hello Message Exchange - Periodically exchanging the Hello frame –Advertising 1-hop neighbor information Upon receiving the Hello frame 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 802.11-05/0386r0 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 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 7 Topology Discovery - ASAT & TC Messages - Mesh AP generates an ASAT (Associated Station Address Table) frame which records a MAC address table of legacy STA associated with it. MP generates a TC (Topology Control) frame 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 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 8 Topology Discovery - ASAT & TC Message Forwarding - MPR forwards the ASAT & TC frames from its MPR selectors. Flooding ASAT & TC frames to all MPs in the network to construct the route 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 selector) 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 MP AP-A broadcasts the ASAT frames(1) MP-B retransmitted the ASAT frame by replacing SA with MAC:B (2) MP-B (MPR selector)

9. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 9 Example with Unicast Route Forwarding the unicast frame from STA1 to STA2 1.Upon receiving a frame from STA1, Mesh-AP1 refers the ASAT of every Mesh-AP, and knows that it is associated with Mesh-AP3 (see the figure). 2.Based on the route to Mesh-AP3, Mesh-AP1 sends the transformed WDS frame by setting the RA to Mesh-AP2, TA to Mesh-AP1, SA to STA1 and DA to STA2. 3.Upon receiving the WDS frame, Mesh-AP2 checks the ASAT of every Mesh-AP like Mesh-AP1, and then forwards it by resetting RA to Mesh- AP3, TA to Mesh-AP2 in the WDS frame. 4.Upon receiving the frame from Mesh-AP2, Mesh-AP3 transforms the WDS frame into the data frame of the infrastructure mode, and then forwards it to STA2. STA1 Mesh-AP1Mesh-AP2Mesh-AP3 STA2 (1) (2)(3) (4)

10. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 10 Example with Broadcast Route STA1 Mesh-AP1Mesh-AP2Mesh-AP3 STA4 (1) (2)(3) (4) STA2STA3 (2)(3) Forwarding the broadcast frame from STA1 1.STA1 sets DA to the broadcast address, and then sends this data frame. 2.Upon receiving the frame from STA1, Mesh-AP1 transforms it into the WDS frame, and then forwards this WDS frame by setting TA to Mesh- AP1. Note that Mesh-AP1 also broadcasts the data frame to the STAs associated with it. 3.Since Mesh-AP2 is selected as MPR of Mesh-AP1, it forwards the received WDS frame by setting TA to Mesh-AP2. Note that Mesh-AP2 also broadcasts the data frame retransformed from the WDS frame, to the STAs associated with it. 4.Upon receiving the WDS frame from Mesh-AP2, Mesh-AP3 retransforms it into the data frame and broadcasts it to the STAs associated with it.

11. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 11 Supporting quality of service over mesh networks for the real time application –Support the multiple paths for load balancing Every flow trends to choice the same route with less hop numbers. As a result, some MPs are heavily loaded. Flow based multi-path routing distributes the traffic over the whole networks. –Support the delay based priority control Many applications (VoIP, Game) are delay sensitive In mesh networks, end-to-end delay varies depending on number of hops, congestion at intermediate nodes etc. End-to-end delay based fairness must be supported. QoS Support

12. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 12 Load Balancing - Problem Specification - Why load balancing using multiple paths is required –MP usually manages only a path to each destination. –Then all traffic to a destination run down into the path. –It is better 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 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 13 Load Balancing - Related Research - Existing Method : Round-Robin Scheme –MP randomly selects an RA (= next-hop MP) for each packet destined to the same DA by round-robin method. 1327504689 Path Index DARA p173 p274 Routing Table with Multiple Paths Merits –Easy to implement. Demerits –It causes packets to be out of order.

14. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 14 Load Balancing - Pseudo Flow Based Scheme - Proposing Method : Pseudo Flow Based Scheme –Pseudo flow : Type 1 : Identified by DA and SA Type 2 : Identified by DA and TA (= previous-hop MP) –MP generates a pseudo flow table. –MP 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. –Packets keep in order. Demerits –Cross grained.

15. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 15 Delay Based Priority Control - Problem specification - Consider the same type of traffics End-to-end delay increases with increase of number of hops, congestion and so on! Delay based priority control scheme must be considered! 146532 Small number of hops: Allowed delay: 4 sec; Actual delay: 2 sec 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: 4 sec Actual delay: 5sec 1 6, Allowed delay: 4 sec 2 4, Allowed delay: 4 sec

16. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 16 Outline of the proposed scheme –Intermediate nodes dynamically prioritize packets based on their delay requirement and the actual delay characteristics the same traffic type the same delay requirement the actual delay characteristics vary because of –number of hops –network condition (congestion) –Intermediate nodes forward packets based on the priority level Approaches –Prioritizing mechanism based on number of hops –Prioritizing mechanism based on time stamp –Prioritizing mechanism based on congestion at intermediate nodes Delay based Priority Control

17. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 17 Intermediate MPs prioritize packets based number of hops –Number of hops can be achieved from the routing table –Longer 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

18. doc.: IEEE 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 18 Multiple Radios - Distributed Channel Assignment (CA) - Premise –Two interfaces/radios, more channels Requirements for distributed CA –Minimizing co-channel interference –Auto configuration of the mesh network Basic principle –Least used channel first Main problem –Guarantee connectivity –Both ends of a link share the common channel IF0 IF1 C B D A

19. doc.: IEEE 802.11-05/0386r0 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: Change 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: Change channel –S8: Update CA sequence number and continue CA IF0 IF1 CB A D

20. doc.: IEEE 802.11-05/0386r0 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 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 21 CA for the Newly Joining Mesh AP New MAP monitors the default channel New MAP passively scan other channels New MAP selects the least used channel New MAP sends Reserve message to the desired neighbor The neighbor response with 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 802.11-05/0386r0 Submission Bing Zhang, et al. May 2005 Slide 22 Conclusions A proposal for mesh networks with a proactive scheme is proposed: –Accommodate the legacy STA associated with Mesh AP –Optimize the amount of link-state information –Support unicast and broadcast QoS support –Path Load Balancing Balance the load of path –Delay based priority control Prioritizing mechanism based on number of hops Multiple radios –Assign the channels with a distributed scheme