doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 1

BSS Transition with BearingDate: 2009-11-17

Name Affiliations Address Phone email Allan Thomson Cisco Systems 170 W. Tasman Drive, San

Jose, CA95134 +1-408-853-5570 allant@cisco.com

Authors:

doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 2

Abstract

This proposal is submitted as a solution to SB CID#7355400023

Today many clients have the capability to determine bearing (direction) and relative height to aid with navigation

This proposal leverages that capability to improve client roaming behavior

doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 3

The problem…• BSS Transition Management provides information to the client to

aid client roaming• Today the Neighbor Report element included in the BSS

Transition Management Request frame includes BSSID, Reg Class, Channel and various additional sub-elements related to the BSSID

• One such sub-element is BSS Transition Preference• This indicates the relative preference from the “network-side” of

what APs should be considered by the client for roaming to– This information is not based on what the client is actually doing

• For clients that are in motion and have bearing information, there is no information available from the network that indicates which APs are in the path of the client

• Therefore AP provided preferences cannot always help clients while in motion

doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 4

The solution…

• Provide a mechanism for the AP network to notify STAs for each AP neighbor the relative bearing and height of AP neighbors from the AP reporting the information

• Therefore allowing the STA to choose an appropriate AP transition if that STA knows its direction while in motion

doc.: IEEE 802.11-09/1128r1

Submission

Example #1• Associated AP12 reports

preferred transition candidates (all candidates same height):

– AP7 (0degs)

– AP8 (20degs)

– AP13 (25degs)

– AP6 (340 degs)

– AP11 (320degs)

– …etc

• Client knows 0 == North

• Client knows that it is facing/moving bearing 22degs

• Client chooses AP8 or AP13

Nov 2009

Allan Thomson, Cisco SystemsSlide 5

doc.: IEEE 802.11-09/1128r1

Submission

Example #2: Client same distance from AP12 but different position

• Client could be anywhere on the grey circle

• AP12 continues to report same transition information as Example 1

• Client still knows that it is moving towards 22degs

• Client chooses AP neighbors based on direction of travel

Nov 2009

Allan Thomson, Cisco SystemsSlide 6

doc.: IEEE 802.11-09/1128r1

Submission

Example #3: Client walking up to a building

• Client walking to building can see APs on 1st, 2nd and 3rd floors

• AP on 1st floor reports APs on same floor and 2nd floor in candidate list

• Client chooses AP neighbors based on 1st floor level as reporting BSS

Nov 2009

Allan Thomson, Cisco SystemsSlide 7

F5

F1

F2

F3

F4

Blg 1

Direction

AP

reachable

doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 8

Solution Details

• Add new Bearing sub-element to Neighbor Report

doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 9

Sub-element Details

• Single field indicating Bearing and Relative Height

• Bearing indicates the direction of the neighbor in degrees relative to the reporting BSS and in relation to true north

• Relative Height indicates the +/- distance in meters between the reporting BSS and the neighbor BSS– 0 indicates the reporting BSS does not know the relative height

difference or the neighbor is at the same height

Subelement ID Length Bearing Relative Height

Octets: 1 1 2 2

Figure 7-XX— Bearing subelement field format

doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 10

Questions ?

doc.: IEEE 802.11-09/1128r1

Submission

Nov 2009

Allan Thomson, Cisco SystemsSlide 11

Motion

• Move to incorporate the normative text in 09/1129r0 into the TGv draft

• Yes:

• No:

• Don’t care: