1 introduction to ieee standardization & ieee 802.11s hang liu thomson inc, corporate research...
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Introduction to IEEE Standardization & IEEE 802.11s
Hang Liu
Thomson Inc, Corporate Research LabPrincetion, NJ
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IEEE Standard Association [1]
Standards Activities Board
802.3CSMA/CDEthernet
802.5Token
Passing Ring
802.11Wireless
LAN
802.15WirelessPersonal
Area Networks
802.20Mobile
BroadbandWirelessAccess
802.19Co-existence
TAG
SponsorIEEE 802
Local and Metropolitan Area Networks(LMSC)
Sponsor Sponsor Sponsor
802.17ResilientPacketRing
802.18Radio
RegulatoryTAG
802.16Broadband
WirelessAccess
802.21Media
IndependentHandoff
802.1HigherLayerLAN
Protocols
802.22WirelessRegional
AreaNetworks
Wired Wireless
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Standardization Process
Disclaimer: The flowcharts for IEEE standardization process are based on the author’s understanding, not official IEEE Policies and Procedures
Incubation: Present initial Idea for a standard or improvement to
a standard (e.g. IEEE 802.11 WNG SC)
Request to form a Study Group
Form an ad-hoc group to continue to present ideas and gain interests
Approved by Working Group (>=75%) & ExeCom?
SG: gain support, prepare and submit a PAR to become a Task Group
PAR Approved by WG (>=75%), ExeCom, NESCom?
TG: Debate technology, write a draft standard
Address comments
Address comments & revision
No
No
Yes
Yes
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Draft Standard Development in TGDefine usage model, requirements, proposal down-
selection procedure, call for proposals
Proposal presentations, merge, and down-selection
Call for Proposals
Baseline document
Each Document Passage requires 75% or greater approval
Approval (>= 75%)
Draft Refinement and Letter Ballot Recirculation
Sponsor Ballot
Yes
No
Refine/enhance the draft baseline and resolve the comments(features could be added/deleted/changed)
Yes
WG Letter Ballot
Approval?
ReVCom
Standard
Resolve comments
No
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Proposal Down-Selection Process: Example 1
1st round proposal presentations and voting
Bottom 25%?
Yes
No
Out
2st round proposal presentations and voting
Support Votes >= 50%?
No
Out
Confirmation vote on the final proposal as baseline draft
(>=75%)?
Final two or three most popular proposals come
back, compete and merge
Yes
No
3st round proposal presentations (normally 2 or 3 merged proposals left)
Yes
Most supported proposal?
One winning proposal
Yes
No
Out
Baseline document
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Proposal Down-Selection Process: Example 2
Define a baseline ToC according to requirements
Present the proposal + proposed text
Support Votes >= 75%?No
Out
Incorporate into the baseline
Yes
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Modify the Baseline
Submit a comment on the baseline
Present the modification + proposed text
Support Votes >= 75%?No
Out
Incorporate the proposed change into the baseline
Yes
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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
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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
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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
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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.
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IEEE 802.11s Deployment Scenarios
Safety/Military NetworksCampus/Public Networks
Office Networks Residential Networks
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A Network Example
Internet
Ethernet
Mesh 2Mesh 1
Router
Mesh portal
Mesh AP
Mesh Point (MP)
Legacy AP
Layer 2 LAN segment
Layer 2 LAN segment
Ethernet
Mesh Point (MP)
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Mesh MAC Architecture
EDCA Enhancement
DCF
11a/11b/11g/11n PHY
Routing Security
Mesh Interworking
Discovery
Other MAC
Mesh Topology and Discovery Security
802.11i link security enhancement Routing
Hybrid Wireless Mesh Protocol Mac Enhancement
EDCA-based, MDA (optional)
Interworking Powersaving
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Device Classes in a Mesh Network
Mesh Point (MP) Mesh AP (MAP) Mesh Portal (MPP) Station (STA)
PortalMP
STA
External Network
MPAP
MPAP
STA
MP
STA STA
Mesh PointMesh Portal
Mesh AP
Station
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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
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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
Association Request (incl. mesh IEs, e.g., RSNie) Association Request (incl. mesh IEs, e.g., RSNie)
Association Response (incl. mesh IEs)Association Response (incl. mesh IEs)
Beacon (incl. mesh IEs, e.g., Hello, RSNie, …)Beacon (incl. mesh IEs, e.g., Hello, RSNie, …)
802. 1x EAP Auth
802.1X EAP Request802.1X EAP Request
802.1X EAP Response802.1X EAP Response Access RequestAccess Request
EAP Authentication Protocol ExchangeEAP Authentication Protocol Exchange
Accept (Keys)Accept (Keys)
802.1x Success802.1x Success
Pairwise Keys / Group Keys Establishment
Secure Communications (encrypted)Secure Communications (encrypted)
Data, Mesh management framesData, Mesh management frames
MP1MP2 AS
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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).
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802.11i Basics
Supplicant Authenticator AS
EAP Request
EAP Response Access Request (EAP Request)
EAP Authentication Protocol Exchange
Accept/EAP Success/Key Material
EAP Success
Supplicant Authenticator
Message 1: EAPOL-Key(ANounce, unicasts)
Message 3: EAPOL-Key(Install PTK, unicast, MIC, Encrypted GTK)
PMK knownGenerate SNouce
PMK knownGenerate ANouce
Drive PTK
Message 2: EAPOL-Key(SNounce, unicasts, MIC)
Drive PTKGenerate GTK
Message 4: EAPOL-Key(unicast, MIC)
Install PTKInstall PTK and
GTK
IEEE 802.1X EAP Authentication Establishing Pairwise and Group Keys via four way handshake
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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
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12
6
4
3
X
Capabilities: Path Selection: HWMP, Metrics: airtime, latency
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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
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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
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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)
Source Destination
Source floods PREQ Source
Destination
Reply PREP
Mesh gateway floods proactive PREQ or root announcement to proactively establish the routes to it
MP may send a PREP or PREQ to the gateway to establish a path from the mesh gateway to the mesh point
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Routing Metric
Airtime: the amount of channel resources consumed by transmitting the frame over a particular link.
pt
tpcaa er
BOOc
1
1 Oca, Op and Bt are
constants r: link bit rate ept: frame error rate
Parameter Value (802.11a)
Value (802.11b)
Description
Oca 75s 335s Channel access overhead
Op 110s 364s Protocol overhead
Bt 8224 8224 Number of bits in test frame
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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
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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
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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.
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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