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Introduction to IEEE Standardization & IEEE 802.11s. Hang Liu Thomson Inc, Corporate Research Lab Princetion, NJ. Standards Activities Board. Sponsor IEEE 802 Local and Metropolitan Area Networks (LMSC). Sponsor. Sponsor. Sponsor. 802.17 Resilient Packet Ring. 802.3 CSMA/CD
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Introduction to IEEE Standardization & IEEE 802.11s Hang LiuThomson Inc, Corporate Research LabPrincetion, NJ
Standards Activities Board Sponsor IEEE 802 Local and Metropolitan Area Networks (LMSC) Sponsor Sponsor Sponsor 802.17 Resilient Packet Ring 802.3 CSMA/CD Ethernet 802.5 Token Passing Ring 802.1 Higher Layer LAN Protocols 802.16 Broadband Wireless Access 802.11 Wireless LAN 802.19 Co-existence TAG 802.21 Media Independent Handoff 802.15 Wireless Personal Area Networks 802.18 Radio Regulatory TAG 802.22 Wireless Regional Area Networks 802.20 Mobile Broadband Wireless Access Wired Wireless IEEE Standard Association [1]
Incubation: Present initial Idea for a standard or improvement to a standard (e.g. IEEE 802.11 WNG SC) Form an ad-hoc group to continue to present ideas and gain interests Request to form a Study Group No Approved by Working Group (>=75%) & ExeCom? Address comments Yes SG: gain support, prepare and submit a PAR to become a Task Group No Address comments & revision PAR Approved by WG (>=75%), ExeCom, NESCom? Yes TG: Debate technology, write a draft standard Standardization Process • Disclaimer: The flowcharts for IEEE standardization process are based on the author’s understanding, not official IEEE Policies and Procedures
Define usage model, requirements, proposal down-selection procedure, call for proposals Each Document Passage requires 75% or greater approval Call for Proposals Proposal presentations, merge, and down-selection Baseline document Refine/enhance the draft baseline and resolve the comments (features could be added/deleted/changed) No WG Letter Ballot Approval (>= 75%) Yes Draft Refinement and Letter Ballot Recirculation Sponsor Ballot Resolve comments Approval? Yes No ReVCom Standard Draft Standard Development in TG
1st round proposal presentations and voting Yes Out Bottom 25%? No 2st round proposal presentations and voting No Out Support Votes >= 50%? Yes 3st round proposal presentations (normally 2 or 3 merged proposals left) No Out Most supported proposal? Yes Final two or three most popular proposals come back, compete and merge One winning proposal No Confirmation vote on the final proposal as baseline draft (>=75%)? Yes Baseline document Proposal Down-Selection Process: Example 1
Define a baseline ToC according to requirements Present the proposal + proposed text No Out Support Votes >= 75%? Yes Incorporate into the baseline Proposal Down-Selection Process: Example 2
Submit a comment on the baseline Present the modification + proposed text No Out Support Votes >= 75%? Yes Incorporate the proposed change into the baseline Modify the Baseline
Voting Rights [1], [2] • 2 types of meeting sessions • Plenary: 3 sessions per calendar year (March, July, November) • Organized by IEEE 802 • Interim: 3 sessions per calendar year (January, May, September) • Organized by working group and sponsored by a host • IEEE 802.11/.15/.18/.22 • IEEE 802.16 • Voting rights can be earned by participation in 2 of the last 4 consecutive plenary sessions or 1 plenary and 1 interim. • Voting rights are only granted in “Plenary Sessions”. • Definition of participation • Must be present in at least 75% of ALL meetings in a session
Maintain Voting Right [1] • Loose the Voting Right by one of the following • Fail to participate at least 2 out of 4 consecutive Plenary sessions • Participation is to attend 75% of ALL meetings within a session • May substitute one Interim session for Plenary • Fail to respond and vote on 2 out of 3 mandatory WG letter ballots • Fail to pay either Interim or Plenary conference fees
Highlights of the IEEE Patent Policy [2] [5] • Participants have a duty to tell the IEEE if they know (based on personal awareness) of potentially Essential Patent Claims they or their employer own • Participants are encouraged to tell the IEEE if they know of potentially Essential Patent Claims owned by others • This encouragement is particularly strong as the third party may not be a participant in the standards process • Working Group is required to request assurance • Early assurance is encouraged • Terms of assurance shall be either: • Reasonable and nondiscriminatory, with or without monetary compensation; or, • A statement of non-assertion of patent rights • Assurances • Shall be provided on the IEEE-SA Standards Board approved LOA form • May optionally include not-to-exceed rates, terms, and conditions • Shall not be circumvented through sale or transfer of patents • Shall be brought to the attention of any future assignees or transferees • Shall apply to Affiliates unless explicitly excluded • Are irrevocable once submitted and accepted • Shall be supplemented if Submitter becomes aware of other potential Essential Patent Claims • A “Blanket Letter of Assurance” may be provided at the option of the patent holder • A patent holder has no duty to perform a patent search • Full policy available at http://standards.ieee.org/guides/bylaws/sect6-7.html#6
IEEE-SA Standards Board Bylaws on Patents in Standards [2] [5] 6.2 Policy IEEE standards may be drafted in terms that include the use of Essential Patent Claims. If the IEEE receives notice that a [Proposed] IEEE Standard may require the use of a potential Essential Patent Claim, the IEEE shall request licensing assurance, on the IEEE Standards Board approved Letter of Assurance form, from the patent holder or patent applicant. The IEEE shall request this assurance without coercion. The Submitter of the Letter of Assurance may, after Reasonable and Good Faith Inquiry, indicate it is not aware of any Patent Claims that the Submitter may own, control, or have the ability to license that might be or become Essential Patent Claims. If the patent holder or patent applicant provides an assurance, it should do so as soon as reasonably feasible in the standards development process once the PAR is approved by the IEEE-SA Standards Board. This assurance shall be provided prior to the Standards Board’s approval of the standard. This assurance shall be provided prior to a reaffirmation/stabilization if the IEEE receives notice of a potential Essential Patent Claim after the standard’s approval or a prior reaffirmation/stabilization. An asserted potential Essential Patent Claim for which an assurance cannot be obtained (e.g., a Letter of Assurance is not provided or the Letter of Assurance indicates that assurance is not being provided) shall be referred to the Patent Committee. A Letter of Assurance shall be either: a) A general disclaimer to the effect that the Submitter without conditions will not enforce any present or future Essential Patent Claims against any person or entity making, using, selling, offering to sell, importing, distributing, or implementing a compliant implementation of the standard; or b) A statement that a license for a compliant implementation of the standard will be made available to an unrestricted number of applicants on a worldwide basis without compensation or under reasonable rates, with reasonable terms and conditions that are demonstrably free of any unfair discrimination. At its sole option, the Submitter may provide with its assurance any of the following: (i) a not-to-exceed license fee or rate commitment, (ii) a sample license agreement, or (iii) one or more material licensing terms.
Residential Networks Office Networks Campus/Public Networks Safety/Military Networks IEEE 802.11s Deployment Scenarios
A Network Example Ethernet Internet Router Mesh portal Ethernet Mesh Point (MP) Legacy AP Mesh 1 Mesh Point (MP) Mesh 2 Layer 2 LAN segment Mesh AP Layer 2 LAN segment
Mesh Interworking Routing Security Discovery Other MAC EDCA Enhancement DCF 11a/11b/11g/11n PHY Mesh MAC Architecture • Mesh Topology and Discovery • Security • 802.11i link security enhancement • Routing • Hybrid Wireless Mesh Protocol • Mac Enhancement • EDCA-based, • MDA (optional) • Interworking • Powersaving
External Network Mesh Portal Mesh Point Portal MP MP MP AP Mesh AP MP AP Station STA STA STA STA Device Classes in a Mesh Network • Mesh Point (MP) • Mesh AP (MAP) • Mesh Portal (MPP) • Station (STA)
Topology Formation • MPs discover candidate neighbors using beacons and probe response frames • Mesh ID, Mesh Capability Element • Mesh Services are supported by new IEs (in action frames), exchanged between associated MP neighbors • E.g. path selection information etc. • Membership in a mesh network is determined by secure association with neighbors • Simple channel unification mode • follow rules to coalesce into a common, fully connected graph on one channel • Advanced mode (multi-radio, multi-channel) • framework for flexible channel selection algorithms beyond the standard scope
MP2 AS MP1 Beacon (incl. mesh IEs, e.g., Hello, RSNie, …) Association Request (incl. mesh IEs, e.g., RSNie) 802. 1x EAP Auth Association Response (incl. mesh IEs) 802.1X EAP Request 802.1X EAP Response Access Request EAP Authentication Protocol Exchange Accept (Keys) 802.1x Success Pairwise Keys / Group Keys Establishment Secure Communications (encrypted) Data, Mesh management frames MP Boot Sequence • Active/passive scanning to discover other MP • Channel selection • Begin mesh beaconing. • Neighbor MP link establishment • Local link state measurement • Routing initialization • AP initialization if mesh AP
Security Framework • Provide link security based on 802.11i: • Authenticity requires that a MP is authenticated to be true before it is allowed getting in the mesh. • Confidentiality requires that no non-trusted third parties can access the messages • Integrity requires that the messages can not be altered during the transit without detection. • Support centralized and distributed IEEE 802.1x-based authentication and key management • A mesh point performs Supplicant and Authenticator roles, and may optionally perform the role of an Authentication Server (AS).
802.11i Basics • IEEE 802.1X EAP Authentication • Establishing Pairwise and Group Keys via four way handshake
3 6 5 8 7 4 1 2 X Capabilities: Path Selection: HWMP, Metrics: airtime, latency Extensible Routing Framework • Layer 2 routing based on MAC addresses • Extensible Routing Protocol Architecture • Allow a vendor to implement any path selection protocol and/or path selection metric to meet special application requirements and optimize the performance. • One routing protocol is operated in a specific mesh network • In beacon and probe response messages, advertise routing capability Mesh Identifier: Mesh 1 Mesh Profile: (HWMP, airtime metric) • Specify a default mandatory routing protocol: Hybrid Wireless Mesh Protocol (HWMP) • Combine the flexibility of on-demand path selection with proactive topology tree building
On-demand Routing vs. Proactive Routing • On-demand Routing: discovers and maintains routes only when they are needed. • Pros: Low routing overhead • Cons: Extra route discovery delay and data buffering • Proactive Routing: each node maintains routes to all reachable destinations at all times, whether or not there is current need to deliver data to those destinations. • Pros: Little delay • Cons: High routing overhead to keep the routing information current • especially when network topology changes frequently • HWMP combines the advantages of on-demand and proactive routing schemes • On-demand for peer-to-peer communications • Proactive route establish for communications with gateway and other important nodes
Destination Source Destination Source floods PREQ Source Reply PREP MP may send a PREP or PREQ to the gateway to establish a path from the mesh gateway to the mesh point Hybrid Wireless Mesh Protocol (HWMP) • On-demand: Use route request/route reply to discover the route on-demand (reduce routing overhead) • Proactive: Gateway proactively announce itself to establish route to reach it (reduce route discovery delay) Mesh gateway floods proactive PREQ or root announcement to proactively establish the routes to it
Routing Metric • Airtime: the amount of channel resources consumed by transmitting the frame over a particular link. • Oca, Op and Btare constants • r: link bit rate • ept: frame error rate
References [1] IEEE 802.11-04/422r7, “New Participant Orientation” [2] IEEE 802.11-08/0333r0 “General 802.11-Opening-Presentation” [3] “IEEE Project 802 LMSC Policies and Procedures,” http://standards.ieee.org/board/ LMSC.pdf [4] IEEE 802.11-11-07-0360-04, “IEEE 802.11 Working Group Policies and Procedures” [5] IEEE Patent Policy, http://standards.ieee.org/board/pat/pat-slideset.ppt [6] IEEE 802.11s Mesh Networking, D1.06 [7] IEEE 802.11-06/0329r3, “Joint SEE-Mesh/Wi-Mesh Proposal to 802.11 TGs Overview,” March 2006 [8] IEEE 802.11s Tutorial, Nov. 2006
Simple Channel Unification Protocol • At boot time, an MP logical radio interface shall perform passive scanning to discover neighboring MPs • If an MP is unable to detect any neighbor MPs, • Adopt the Mesh ID for its highest priority profile, • Select a channel for operation • Select an initial channel precedence value. • the number of microseconds since the boot time of the mesh point plus a random value. • In the event that a mesh point logical radio interface discovers a disjoint mesh, that is, the list of candidate peer Mesh Points spans more than one channel, • Select the channel that is indicated by the candidate peer Mesh Point that has the numerically highest channel precedence indicator to be the unification channel • If the identified unification channel is different than the current operating channel • the mesh point shall execute the channel cluster switch protocol
Channel Switch Protocol • The mesh point determines the need to switch the channel • chooses a channel cluster switch wait timer • sends a channel cluster switch announcement frame to each peer mesh point which contains • the new candidate channel, new candidate channel precedence indicator, channel switch wait time • Receive a channel cluster switch frame • If new candidate channel precedence indicator > the current channel precedence value • set the channel cluster switch timer and send the channel cluster switch announcement frame to each peer mesh point • it is possible that more than one mesh point initiate channel switch simultaneously • If a mesh point receives more than one channel cluster switch announcement frame, it only acts upon the frame if the channel precedence value is larger than the channel precedence value of a previously received channel cluster switch announcement frame. • In case a newly received channel cluster announcement frame has the same channel precedence value as a previously received frame, the new frame is acted upon only if the source address is smaller than the source address from the previously received frame.
Mesh Formation • Peer Link Setup and Maintenance • A MP must select which MPs to establish peer links based on some measure of signal quality or other statistics received from candidate neighbor MPs. • A MP may be configured with the maximum number of peers • Local Link State Discovery and Maintenance • Measure local link quality • Mesh Portal Discovery • Portal information and metric to portal contained in beacons
Basic Security Model Authenticator Supplicant WLAN Mesh Security bubble New Mesh Point