1. Proposal for ESS Mesh Date: 2005-03-16 Authors:
doc.: IEEE /0165r0
March 2005
March 2005
Proposal for ESS Mesh
Date:
Authors:
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SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

2. Contents What is ESS Mesh? ESS Mesh Architecture
doc.: IEEE /0165r0
March 2005
March 2005
Contents
What is ESS Mesh?
ESS Mesh Architecture
ESS Mesh Functional Components
Possible Directions for ESS Mesh
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

3. What is ESS Mesh? Extended Service Set (ESS) What does ESS provide?
doc.: IEEE /0165r0
March 2005
March 2005
What is ESS Mesh?
Extended Service Set (ESS)
A set of one or more Basic Service Sets (BSSs) interconnected by Distribution System (DS)
What does ESS provide?
ESS enables the MAC to transport MSDUs between stations that are not in direct communication with each other over a single instance of the wireless medium through Distributed System Service (DSS)
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

4. doc.: IEEE /0165r0
March 2005
March 2005
Distributed System
Transport of MSDUs (unicast, broadcast, multicast) transparently to upper layers :
between stations in the same BSS - IntraBSS
between the access points (APs) in ESS - InterBSS
between portals and BSSs in ESS
STA1
STA 2
STA 3
STA 4
MSDU
STA 5
MSDU
Logical
Link Layer
MAC /PHY AP AP
MAC /PHY
Portal
DSS
DSS
ESS
BSS 1
BSS 2 DS
802.x LAN
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

5. Distributed System Services
doc.: IEEE /0165r0
March 2005
March 2005
Distributed System Services
Service
Description
Association
The service to establish access point/station (AP/STA) mapping and to enable STA to invocate the distribution system services (DSSs)
Authentication
The service to establish the identity of one station as a member of the set of stations authorized to be associated with another station
Deauthentication
The services to void an existing authentication relationship
Disassociation
The service to remove an existing association relationship
Reassociation
The service to enable an established association relationship
Distribution
The service to deliver MSDUs in DS
Integration
The service to deliver MSDUs between DS and existing, non-IEEE LAN via Portal 1 2 3 4 5 6 7
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

6. Distributed System Services (cont’d)
doc.: IEEE /0165r0
March 2005
March 2005
Distributed System Services (cont’d)
STA1
STA 2
STA 3
STA 4
STA 5
Logical
Link Layer
Mesh AP
Mesh AP
Mesh
Portal 1 1
DSS 1 1 1
( Wired  Wireless )
Parts to be changed
DSS 2 2 2 2 2
ESS 3 3 3 3 3 DS 4 4 4 4 4 5 5 6 6 5 5 5 6 7
BSS 1
BSS 2
802.x LAN
MAC /PHY
MAC /PHY
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

7. ESS Mesh LAN Architecture
doc.: IEEE /0165r0
March 2005
March 2005
ESS Mesh LAN Architecture
Router
Extended Service Set
Bridge
Mesh Portal +
Mesh AP
Mesh Point AP
STA
MESH
Mesh Point
Mesh Link
BSS
Mesh AP
STA
BSS
Mesh AP
STA
BSS
Mesh AP
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

8. Interoperability Mesh Points doc.: IEEE 802.11-05/0165r0 March 2005
Mesh Portal +
Mesh AP +
Mesh AP +
Interoperability
802.X
BSSs Connected by Wireless DS
Mesh Points
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

9. 802.11s Mesh Functional Elements
doc.: IEEE /0165r0
March 2005
March 2005
802.11s Mesh Functional Elements
Mesh Internetworking
Mesh Config.
and Mgmt.
Compatibility to
802.11
Services
Mesh Topology
Learning,
Routing, and
Forwarding
Mesh Discovery
and Association
Mesh
Security
Mesh Medium
Access
Coordination
Mesh Measurement
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

10. Possible Directions for ESS Mesh
doc.: IEEE /0165r0
March 2005
March 2005
Possible Directions for ESS Mesh
Enhanced MAC
Multi-channel support
Discovery and Association for ESS Mesh
Support passive and active discovery mechanism
Routing and Forwarding
Layer 2 Routing
Efficient Route Building among Mesh Point, Mesh AP and Mesh Portal
Minimized cost to route STAs through Mesh AP and Mesh Portal
Flexible path selection for Usage Model
Enhanced Security
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

11. Multi-Channel Support
doc.: IEEE /0165r0
March 2005
March 2005
Multi-Channel Support
Why Multi-Channels?
To exploit orthogonal multiple channels
- 3 channels in b
- 12 channels in a
To improve throughput
- Allow simultaneous transmission
How to Use Multi-Channels?
By extending DCF
to accommodate multi-channel support
By enabling mesh points to listen to
others through different channels
By tuning trade off between
- Reducing interference
- Maximizing channel utilization Y X Q Z
defer Y X Q Z
Single channel
Multiple channels
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

12. Routing Considerations
doc.: IEEE /0165r0
March 2005
March 2005
Routing Considerations
Reactive
Update routing info only when it is needed
Pros: Low control overhead for routing
with spares and little traffic
 but unbounded
Cons: High route acquisition latency
Frequent control msg flooding
with high mobility and variable
traffic pattern and peers
Weak : Distributed & short lived traffic
Strong : Mobility & network size
Proactive
Periodically update routing info among
Mesh Point, Mesh AP, Mesh Portal
Pros: Global topology
Low latency
Easy QoS support
Cons: Large routing table
High control overhead for routing
 but bounded cost
Weak : Mobility, network size
Strong : Distributed traffic pattern
ESS Mesh  Low mobility & moderate network size & distributed traffic patterns
Proactive is beneficial
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

13. Proactive Routing for ESS Mesh
doc.: IEEE /0165r0
March 2005
March 2005
Proactive Routing for ESS Mesh
Main Actions to Select Routes
among Mesh Points, Mesh APs, Mesh Portals
Sensing neighbor Mesh Point (or Mesh AP)
Advertising topology information periodically
Minimized info enough to select routing path
Minimized forwarding enough to reach all nodes
Computing routes based on the known topology
Main Advantages
Shorter topology information message
Less forwarding of topology information message
Tolerant to loss of topology information message
Stable as link state routing
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

14. Types of Communications in ESS
doc.: IEEE /0165r0
March 2005
March 2005
Types of Communications in ESS 1
Mesh
AP A
Supported Communication Peers
Through Mesh Points and Mesh APs
- Mesh Point vs. Mesh Point
- Mesh Point vs. STA with a Mesh AP
- STA vs. STAs with a Mesh AP
Through Mesh Portals
- Mesh Point vs. STA with an AP
- STA in a Mesh AP vs. STA with a AP
Mesh
Point A 3
STA 2
MAC/PHY
BSS 2
Wireless
Distribution
System
Mesh
Point B
STA 1
MAC/PHY
Mesh
Point C
Mesh
Portal
bridge
Mesh
AP B
Bound the Cost to Support All Types of Communication in ESS Mesh
Size of forwarding table in ESS Mesh
Time to process the data frame
STA 6
802.X MAC/PHY
802.11
Portal
BSS 5 4
STA 3
MAC/PHY
802.11 AP 4
STA 4
MAC/PHY
MAC/PHY
BSS
STA 5 6
STA 6
MAC/PHY
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

15. Flexible Path Selection
doc.: IEEE /0165r0
March 2005
March 2005
Flexible Path Selection
Path Selection
based on Quality
Defining the parameters
for link quality measurement
Distributing measured
values within ESS Mesh
Computing path quality
based on measured values
Path Selection
based on DCS
Distributing information on
channel usage
Negotiating channels to be used
Selecting channels to be used
Adaptable to Usage Scenarios
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.

16. Enhanced Security Built on 802.11i security Enhanced Security
March 2005
Enhanced Security
Built on i security
Utilizing existing mechanism
for STA to AP security
Existing mechanism only address
STA to AP security
Enhancement needed to address
security between mesh points
Enhanced Security
Network topology and routing
information protection
Security between mesh points (e.g.
APs) via authentication, key
management, and protection of
control message and data
SongYean Cho, Samsung Electronics.

17. Summary ESS Mesh is about : Possible Directions for ESS Mesh
doc.: IEEE /0165r0
March 2005
March 2005
Summary
ESS Mesh is about :
Connecting BSSs (Mesh AP + STA)
Including Mesh Points
Including STAs in 802.X through Mesh Portals
Possible Directions for ESS Mesh
Multi-channel support
Proactive Routing for Mesh
Flexible Path Selection
Enhanced Security
SongYean Cho, Samsung Electronics.
Steven Conner, Intel Corp.