January 2013 doc.: IEEE 802.11-12/0024r0

IEEE P802.11
Wireless LANs

CC4 Comment Resolution – Reduced Neighbor Report
Date: 2013-1-7
Author(s):
Name / Affiliation / Address / Phone / email
Yongho Seok / LG Electronics / +82-31-450-1947 /
Giwon Park / LG Electronics
Peter Ecclesine / CISCO Systems
Santosh Pandey / CISCO Systems


Interpretation of a Motion to Adopt

A motion to approve this submission means that the editing instructions and any changed or added material are actioned in the TGaf Draft. This introduction is not part of the adopted material.

Editing instructions formatted like this are intended to be copied into the TGaf Draft (i.e. they are instructions to the 802.11 editor on how to merge the text with the baseline documents).

TGaf Editor: Editing instructions preceded by “TGaf Editor” are instructions to the TGaf editor to modify existing material in the TGaf draft. As a result of adopting the changes, the TGaf editor will execute the instructions rather than copy them to the TGaf Draft.

CID / Comment / Proposed Change / Resolution
1010 / Beacon frame should contain Supported Regulatory Classes when dot11TVHTOptionImplemented is true. / Change Supported Operating Classes to be present when dot11TVHTOptionImplemented is true. / Accept
1011 / Probe Request and Probe Response frame should contain Supported Regulatory Classes when dot11TVHTOptionImplemented is true. / Change Supported Operating Classes to be present when dot11TVHTOptionImplemented is true. / Accept
1035 / When the SSID in the probe request is the specific SSID (not wildcard SSID),
AP receiving the probe request responds with a probe response only if the SSID in the probe request matches with the SSID of the AP.
As the same logic, it seems that the SSID of the neighbor included in the reduced neighbor report element matches with the SSID in the probe request.
Because it can further reduce the scanning time. / Clarify the neighbour list included in probe response when the SSID in the probe request is the specific SSID. / Accept
1036 / Including the neighbors operating in the non-supported operating classes of STA is waste of resource.
When the supported operating class in the probe request is included, the non-supported operating class of the STA shall not be included in the neighbor information. / Clarify the neighbour list included in probe response when the supported operating class is included in the probe request. / Accept

Discussion:

CID 1010 and CID 1011 are asking to include the Supported Operating Classes in Beacon, Probe Request and Probe Response frames. In TV White Spaces, an active scanning procedure is not allowed because of the regulation requiremend. However, when a STA performs an active scanning procedure in 2.4GHz, it is useful to indicate that it supports TV White Spaces by including the Supported Operating Classes in Probe Request and Probe Response frames. Based on the Supported Operating Classes information, a non-AP STA can decide whether it performs a passive scanning procedure in TV Whtie Spaces or not. Or, AP can provide the neighbor AP information operating in TV Whtie Space to a non-AP STA supporting TV Whtie Spaces.

CID 1035 is asking that the SSID of the neighbor included in the reduced neighbor report element matches with the SSID in the probe request. Because AP responds with a probe response only if a specfici SSID in the probe request matches with the SSID of the AP. This restriction can reduce the scanning time by avoiding the scan of AP that is not matched with SSID in the Probe Request.

CID 1036 is asking that the non-supported operating classes of the STA shall not be included in the neighbor information of the Recuded Neighbor Report element. For example, if AP supporting TV White Spaces always includes the neighbor information in TV White Spaces, it may lose the advantage of the Reduced Neighbor Report because the size of the Reduced Neighbor Report increases.

Propose:

Accept for CID 1010, 1011, 1035 and 1036, per discussion and editing instructions in 11-13/0024r0.

8.3.3.2 Beacon frame format

TGaf Editor: Change the row of Order 36 in Table 8-20 Beacon frame body as follows:

Order / Information / Notes
36 / Supported Operating Classes / The Supported Operating Classes element is present if dot11ExtendedChannelSwitchActivated is true.
The Supported Operating Classes element is optionally present if dot11TVHTOptionImplemented is true.

8.3.3.9 Probe Request frame format

TGaf Editor: Change the row of Order 6 in Table 8-26 Probe Request frame body as follows:

Order / Information / Notes
6 / Supported Operating Classes / The Supported Operating Classes element is present if dot11ExtendedChannelSwitchActivated is true.
The Supported Operating Classes element is optionally present if dot11TVHTOptionImplemented is true.

8.3.3.10 Probe Response frame format

TGaf Editor: Change the row of Order 34 in Table 8-27 Probe Response frame body as follows:

Order / Information / Notes
34 / Supported Operating Classes / The Supported Operating Classes element is present if dot11ExtendedChannelSwitchActivated is true.
The Supported Operating Classes element is optionally present if dot11TVHTOptionImplemented is true.

TGaf Editor: Modify the sub-clause 8.4.2.172.1 as follows:

8.4.2.172.1 Neighbor AP Information field

The format of TBTT Information Header subfield is defined in Figure 8-401cl (TBTT Information Header subfield).

TBTT Information Field Type / Filtered Neighbor AP / Reserved / TBTT Information Count / TBTT Information Length
Bits: / B0 B1 / B2 / B3 / B4 B7 / B8 B15

Figure 8-401cl—TBTT Information Header subfield

The TBTT Information Field Type subfield is 2 bits in length and defines the structure of the TBTT Information field. Its value is 0. Values 1, 2, and 3 are reserved.

The Filtered Neighbor AP subfield is 1 bit in length. It is set to 1 AP if the SSID of APs in this Neighbor Information field matches the specific SSID in the probe request. It is set to 0 otherwise. This field is valid only in the Reduced Neighbor Report element in a Probe Response frame and is reserved otherwise.

The TBTT Information Count subfield is 4 bits in length and contains the number of TBTT Information fields that are included in the Neighbor AP Information field, minus one. A value of 0 indicates one TBTT Information field is present.

10. MLME

10.42 Operation under the control of a geolocation database

TGaf Editor: Modify the sub-clause 10.42.7.1 as follows:

10.42.7.1 Reduced Neighbor Report

In Beacon and Probe Response frames, a reduced neighbor report is optionally sent by an AP with dot11TVHTOptionImplemented true. A reduced neighbor report contains information on neighbor APs. A reduced neighbor report may not be exhaustive either by choice, or due to the fact that there may be neighbor APs not known to the AP.

The Reduced Neighbor Report element contains a list of operating classes and channels along with TBTT information for the reported neighbor APs on each operating class and channel. A Reduced Neighbor Report element only includes channels that are consistent with the Country element in the frame in which the Reduced Neighbor Report element appears. The reduced neighbor report contents may be derived from the NeighborListSet parameter of the MLME-NEIGHBORREPRESP.request primitive. The contents of the reduced neighbor report may also be configured or obtained by other means beyond the scope of this standard.

If the supported operating classes of the STA are included in the probe request, the reduce neighbor report contains information on neighrbor APs whose current operating class matches the supported operating classes in the probe request.

The Reduced Neighbor Report element shall include the information on neighrbor APs whose SSID matches the specific SSID in the probe request if the Filtered Neighbor AP bit in the Neighbor AP Information field is set to 1.

A serving AP shall include a value less than 255 in TBTT Offset in TUs if it is able to guarantee an accumulated error of 1.5 TU or better on the TBTT Offset in TUs subfield.

A STA receiving a Reduced Neighbor Report may use the report to schedule passive scanning for faster AP discovery. The scheduling process is beyond the scope of this standard. A STA receiving a Reduced Neighbor Report element with an unknown subelement identifier shall ignore the unknown subelement and continue to process the remaining subelements.

Submission page 5 Yongho Seok, LG Electronics