1. AP Status Broadcast Date: 2011-11-09 Authors: November 2011
doc.: IEEE /1565r0
November 2011
AP Status Broadcast
Date:
Authors:
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

2. November 2011
doc.: IEEE /1565r0
November 2011
Abstract
This presentation proposes the idea of advertising AP status for avoiding associations to APs with bad performance.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

3. Conformance w/ TGai PAR & 5C
November 2011
doc.: IEEE /1565r0
November 2011
Conformance w/ TGai PAR & 5C
Conformance Question
Response
Does the proposal degrade the security offered by Robust Security Network Association (RSNA) already defined in ? No
Does the proposal change the MAC SAP interface?
Does the proposal require or introduce a change to the architecture?
Does the proposal introduce a change in the channel access mechanism?
Does the proposal introduce a change in the PHY?
Which of the following link set-up phases is addressed by the proposal?
(1) AP Discovery (2) Network Discovery (3) Link (re-)establishment / exchange of security related messages (4) Higher layer aspects, e.g. IP address assignment 1
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

4. November 2011
doc.: IEEE /1565r0
November 2011
Background
Congested or stacked data flows in WLAN communications annoy us. (e.g. Free WLAN spot in Hotels, Airport, etc.)
The reasons are that:
Many STAs are connected to AP.
Backhaul network is slow.
Backhaul network is out of service at the moment. …
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

5. November 2011
doc.: IEEE /1565r0
November 2011
Motivation
It is inconvenient for STA to connect to AP which isn’t operated in well conditions. It is nonsense even if the link setup time of the association is very short.
It is preferred to avoid needless association requests by obtaining status information from AP in advance.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

6. November 2011
doc.: IEEE /1565r0
November 2011
GAS query protocol in 11u
11u has GAS query protocol in order to obtain required information for association before association request. It is exchanged on the action flames.
When we define IEs of GAS query related with AP status and performance, those will be indicators for STAs to determine if a candidate AP is worthy for association or not.
But GAS query request/response are transmitted in uni- cast frames. So, if each STA transmits GAS query request for each attempt of association, it will bring packet flooding problems like as probe request/response.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

7. AP status consultations by GAS query
November 2011
doc.: IEEE /1565r0
November 2011
AP status consultations by GAS query
STA1
STA2
AP1
AP2
Beacon
GAS Query Request
Status analysis
(BAD)
GAS Query Response (AP performance = BAD)
GAS Query Request
Status analysis
(BAD)
GAS Query Response (AP performance = BAD)
Beacon
GAS Query Request
Status analysis
(GOOD)
GAS Query Response (AP performance = GOOD)
Association Request
GAS Query Request
Status analysis
(GOOD)
GAS Query Response (AP performance = GOOD)
Association Request
Packet exchanges in red are garbage.
This kind of packet exchanges will bring packet flooding and it is time wasting for FILS also.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

8. Proposal I’d like to propose that:
November 2011
doc.: IEEE /1565r0
November 2011
Proposal
I’d like to propose that:
TGai compliant AP can include IEs related with AP status and performance in Beacon.
STA1
STA2
AP1
AP2
Beacon with AP status (BAD)
Beacon with AP status (GOOD)
Association Request
Association Request
STAs don’t try to associate with AP1.
Packet exchanges are organized.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

9. BSS Load Element BSS Load Element would be helpful for AP selection.
November 2011
doc.: IEEE /1565r0
November 2011
BSS Load Element
BSS Load Element would be helpful for AP selection.
This element is already defined as the IE of Beacon.
Element ID
Length
Station Count
Channel
Utilization
Available
Admission
Capacity
Octets: 1 1 2 1 2
Station Count:
The total number of STAs currently associated with this BSS.
Channel Utilization:
The percentage of time as indicated by either the physical or virtual carrier sense mechanism.
Available Admission Capacity:
The remaining amount of medium time available.
An IE relating with WAN side status of AP is not defined for Beacon.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

10. And also … Any other IEs for helping AP selection might be considered.
November 2011
doc.: IEEE /1565r0
November 2011
And also …
Any other IEs for helping AP selection might be considered.
APs just transmit Beacon with AP status IEs. They don’t control STA’s behavior. The policy of AP selection on STA depends on vendor or operator implementation. It’s out of scope of TGai.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

11. References Doc.: IEEE 11-11/1413r1 IEEE802.11-2007 November 2011
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories