802'11s Proposal Joint SEEMeshWiMesh Proposal to 802'11 TGs

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802.11s Proposal - Joint SEE-Mesh/Wi-Mesh
Proposal to 802.11 TGs

• IEEE 802.11-06/0328r0
• Feb 2006
• This proposal can be obtained from
  http//www.802wirelessworld.com/.

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Current 802.11s Proposals
Table from Proposals for TGs, IEEE
802.11-05/0597r20
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Outline

• General Description
• Mesh Topology Discovery and Formation
• NEW! Path Selection Hybrid Wireless Mesh
  Protocol (HWMP)
• Interworking Support
• NEW! Multi-Channel Support (CCF) (optional)

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3. Path Selection Hybrid Wireless Mesh Protocol
(HWMP)

• Combines the flexibility of on-demand route
  discovery with the option for efficient proactive
  routing to a mesh portal
• On demand service is based on Radio Metric AODV
  (RM-AODV)
• same as the SEE-mesh
• When a root portal is not configured, RM-AODV is
  used to discover routes to destinations in the
  mesh
• Pro-active routing is not for all links it is a
  tree-based routing
• If a Root portal is present, a distance vector
  routing tree is built and maintained
• advantage
• most traffics are destined to the Root
• can reduce unnecessary route discovery flooding

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• Path Selection Protocol RMAODV
• Radio Metric Ad hoc On-Demand Distance Vector
• Summary of features beyond AODV
• Identify best-metric path with arbitrary path
  metrics
• Reduce flooding when maintaining multiple paths
• Aggregate multiple RREQs in same message
• Modification to RREQ/RREP processing/forwarding
  rules
• Forward RREQ with better metric
• No route caching
• Optional periodic path maintenance
• Allows proactive maintenance of routes to popular
  destinations (e.g. MPP)

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HWMP Example 1 No Root, Destination Inside the
Mesh

• Example MP 4 wants to communicate with MP 9
• MP 4 first checks its local forwarding table for
  an active forwarding entry to MP 9
• If no active path exists, MP 4 sends a RREQ to
  discover the best path to MP 9
• MP 9 replies to the RREQ with a RREP to establish
  a bi-directional path for data forwarding
• MP 4 begins data communication with MP 9

On-demand path
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HWMP Example 2 Non-Root Portal(s), Destination
Outside the Mesh

• Example MP 4 wants to communicate with X
• MP 4 first checks its local forwarding table for
  an active forwarding entry to X
• If no active path exists, MP 4 sends a RREQ to
  discover the best path to X
• When no RREP received, MP 4 assumes X is outside
  the mesh and sends messages destined to X to Mesh
  Portal(s) for interworking
• MP 1 forwards messages to other LAN segments
  according to locally implemented interworking

On-demand path
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HWMP Example 3 Root Portal,Destination Outside
the Mesh

• Example MP 4 wants to communicate with X
• MP 4 first checks its local forwarding table for
  an active forwarding entry to X
• If no active path exists, MP 4 may immediately
  forward the message on the proactive path toward
  the Root MP 1
• When MP 1 receives the message, if it does not
  have an active forwarding entry to X it may
  assume the destination is outside the mesh and
  forward on other LAN segments according to
  locally implemented interworking
• Note No broadcast discovery required when
  destination is outside of the mesh

Root
Proactive path
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HWMP Example 4 With Root,Destination Inside
the Mesh

• Example MP 4 wants to communicate with MP 9
• MP 4 first checks its local forwarding table for
  an active forwarding entry to MP 9
• If no active path exists, MP 4 may immediately
  forward the message on the proactive path toward
  the Root MP 1
• When MP 1 receives the message, it flags the
  message as intra-mesh and forwards on the
  proactive path to MP 9
• When MP 9 receives the message, it may issue an
  on-demand RREQ to MP 4 to establish the best
  intra-mesh MP-to-MP path for future messages

Root
Proactive path
On-demand path
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5. Multi-Channel Support Common Channel
Framework (CCF)

• Using RTX, the transmitter suggests a destination
  channel. (RTX ? RTS)
• Receiver accepts/declines the suggested channel
  using CTX. (CTX ? CTS)
• After a successful RTX/CTX exchange, the
  transmitter and receiver switch to the
  destination channel.
• Switching is limited to channels with little
  activity.
• Existing medium access schemes are reused.

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CCF Example (1)
MP3
MP1
MP4
MP2
CommonChannel
RTX
DataChannel n
DataChannel m
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Channel Coordination

• To increase channel utilization, a channel
  coordination window (CCW) is defined on the
  common channel.
• P is the period with which CCW is repeated.
• MPs should stay tuned to CCW, and may remain in
  the common channel beyond CCW duration.
• P and CCW are carried in beacons.
• At the start of CCW, CCF enabled MPs tune to the
  common channel.
• This facilitates all MPs to get connected.
• Channel Utilization Vector (U) of each MP is
  reset.
• MPs mark a channel as unavailable based on
  information read from RTX/CTX frames.

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CCF Example (2)
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Conclusions

• SEE-Mesh Wi-Mesh for IEEE 802.11s
• New materials
• Hybrid path selection protocol (RM-AODV
  tree-based DSDV)
• Multi-channel support (Channel coordination
  function)