1. Discussions about 802.11ai FILS Discovery Frame (DF) Content Design
Month Year
doc.: IEEE yy/xxxxr0
July 2012
Discussions about ai FILS Discovery Frame (DF) Content Design
Date:
Authors:
Lei Wang, InterDigital Communications
John Doe, Some Company

2. Month Year
doc.: IEEE yy/xxxxr0
July 2012
Abstract
This document is intended to facilitate further discussions about passive scanning enhancement, by presenting some considerations and analysis about the design of the FILS Discovery Frame contents.
This is a follow-up contribution with regarding to ai passive scanning enhancements as discussed in the contributions, 12/0406r5 and 12/0669r1. Also, it is about further details for a feature that has been accepted in the ai SFD.
Lei Wang, InterDigital Communications
John Doe, Some Company

3. Conformance w/ TGai PAR & 5C
Month Year
doc.: IEEE yy/xxxxr0
July 2012
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
1,2
Lei Wang, InterDigital Communications
John Doe, Some Company

4. July 2012
Background
Straws poll conducted in 2012-May meeting about FILS Discovery Frame content design clearly shows two different opinions:
Enough info for initiating association
Certain info for assisting scanning, but need to receive more info for initiating association
This contribution will focus on further discussions about the 11ai FILS Discovery frame content design.
Another related but separate contribution, 12/0742, focuses on the discussions about the 11ai FILS Discovery frame format design.
Lei Wang, InterDigital Communications

5. Basic Approach of FD Frame Content Design
July 2012
Basic Approach of FD Frame Content Design
Investigating Existing Reference Materials
802.11ah Short Beacon
Measurement Pilot Frame
Beacon Frame / Probe Response frame
11ai relevant contributions
Identifying FD Frame contents based on its basic functions:
Advertize the presence of the AP on the channel
Synchronize the STAs
Provide necessary information for a fast AP/Network selection
Provide necessary information to enable STA to transmit
Anything else ???
Lei Wang, InterDigital Communications

6. Recap of 802.11ah Short Beacon Frame
July 2012
Recap of ah Short Beacon Frame
802.11ah has introduced a Short Beacon Frame into 11ah SFD (11/1137r9), based on proposals presented in contributions, 11/1503r2 and 12/129r3;
Overview of 11ah short beacon:
A short beacon allows for reduced medium occupancy
reduced power consumption for TX at AP and RX at STAs
Or, for the same overhead as a ‘normal’ beacon, allows for shorter Beacon Intervals, improving synchronization and power save at the STAs
Asynchronous STAs waking up at a random time can get in synch quickly
The short beacon is not meant to displace the normal beacon
AP may e.g. send a normal ‘full’ beacon every N short beacons
Short beacon is an additional frame for optimized operation
Frame Format and Contents of ah Short Beacon Frame:
Lei Wang, InterDigital Communications

7. Investigation of 802.11ah Short Beacon Frame
July 2012
Investigation of ah Short Beacon Frame
Information
description / Notes
size (bytes)
Apply to 11ai FILS Discovery (FD) frame?
size in 11ai FD frame
Notes
Short Timestamp
used for Time Synchronization Function (TSF); mandatory in 11ah-SB. 4
yes,
Based on slide 11 on the 11ah-short beacon contribution, 11/1503r1, it shows it is sufficient to have 4 bytes TSF field, not 8 bytes.
Change sequence
used to Signal if network information has changed; Mandatory in 11ah-SB; mainly for power saving operations, e.g., sleep mode, after STA's initial association. 1
no, but debatable.
mainly for power saving operations, e.g., sleep mode, after STA's initial association.
time of next full beacon
Informs the STA of the arrival time of the next full beacon; optional in 11ah-SB; 3
Yes, but could be designed to use only 1 byte.
could be designed as an offset value for the FD frame Tx time, so that only need 1 byte in size
conpressed SSID
The SSID element indicates the identity of an ESS or IBSS. optional in 11ah-SB;
Yes,
11ah Proposal 12/0129r3: Compressed SSID should be a hash of the full SSID; and Hashing function should be standardized
Access network options
indicate access services provided by AP/Network; optional in 11ah-SB;
can use the same format as Figure 8-352, in
BSS bandwidth
mandatory in 11ah-SB; inside FC field of the new MAC header design
3bits
yes, but not as a separate parameter.
should be considered as part of the Channel descriptor along with other channel parameters
Lei Wang, InterDigital Communications

8. Recap of Measurement Pilot (MP) Frame
July 2012
Recap of Measurement Pilot (MP) Frame
Based on , the Measurement Pilot (MP) frame
is a compact Action frame transmitted pseudo-periodically by an AP at a small interval relative to a Beacon Interval;
provides reduced information relative to a Beacon frame to allow for the required small interval.
The purpose of the Measurement Pilot frame is to assist a STA with the following functions:
Rapid discovery of the existence of a BSS via passive scanning;
Rapid collection of neighbor AP signal strength measurements via passive scanning;
Enable transmission of a Probe Request.
Lei Wang, InterDigital Communications

9. Recap of Measurement Pilot (MP) Frame – con’t
July 2012
Recap of Measurement Pilot (MP) Frame – con’t
Frame Format and Contents of Measurement Pilot (MP) frame
Lei Wang, InterDigital Communications

10. Investigation of 802.11 Measurement Pilot Frame
July 2012
Investigation of Measurement Pilot Frame
Information
description / Notes
size (bytes)
Apply to 11ai FILS Discovery (FD) frame?
size in 11ai FD frame
Notes
MP interval
basic periodicity of MP frames 1
yes, but it should be changed to FD interval
** in units of TUs (i.e., 1024us)
** is it really needed, considering STA already received the FD frame?
Capability
only two bits are used: spectrum management; short slot time.
yes, but should be re-designed to cover more. 2
to cover critical initial link setup capabilities, based on MP capability and beacon/probe response capability, further capability considerations, e.g., IPv4/IPv6, security capabilities
Country
MP-frame uses a 2-byte condensed country string; although 3 bytes in dot11CountryString
Yes,
operation class
indicates the operating class value for the operating channel, as defined in Annex E.
yes
operation channel
indicates the operating channel, as defined in Annex E.
Lei Wang, InterDigital Communications

11. References in Beacon, Probe Response, and 11ai Contributions
July 2012
References in Beacon, Probe Response, and 11ai Contributions
Lots of additional information items in Beacon and Probe Response frames, as well as in other 11ai contributions;
A fundamental consideration: what other information items are really needed to be transmitted to STA in the first AP-to- STA message for setting up the link?
Channel descriptors
PHY specific info
Security info
BSS/AP load info
Neighbor AP info
What else????
Lei Wang, InterDigital Communications

12. Investigation of Beacon, Probe Response, 11ai Contributions, …
July 2012
Investigation of Beacon, Probe Response, 11ai Contributions, …
Category
Information
description / Notes
size (bytes)
Apply to 11ai FILS Discovery (FD) frame?
size in 11ai FD frame
channel descriptors (beyond Country, Operation class, Operation channel)
power constraints
the information necessary to allow a STA to determine the local maximum transmit power in the current channel. 1
yes
channel bandwidth
the channel bandwidth info is actually provided by the operation class and operation channel.
no, don't need a separate parameter
PHY specific info
ERP (Extended Rate PHY)
11g PHY, 1 byte as used in ERP IE in beacon frame; page 487, 3
yes, PHY dependant
HT operation/HT capability
11n PHY, current HT operation IE, HT capability IE, Overlapping BSS scan IE, and 20/40 coexistence IE 77
yes, PHY dependant, defined a compressed version 2
BSS load info
BSS load / average delay / channel unitlization …
there are 5 BSS load related IEs in current beacon and probe response frame, i.e., 1) BSS load IE: 2+5 bytes 2) BSS Available Admission Capacity IE: 2+2+2*n bytes; 3) QoS Traffic Capability IE: 2+1+n bytes; 4) BSS Average Access Delay IE: 2+1 bytes 5) BSS AC Access Delay IE: 2+4 bytes 35
yes, should be compressed, e.g., an 1-byte indication, either using the average access delay or channel utilization
Lei Wang, InterDigital Communications

13. Apply to 11ai FILS Discovery (FD) frame?
July 2012
Investigation of Beacon, Probe Response, 11ai Contributions, … -- Con’t
Category
Information
description / Notes
size (bytes)
Apply to 11ai FILS Discovery (FD) frame?
size in 11ai FD frame
Security info
secuirty info
Security capability; info from the current RSNE; any other security related info? 48
Yes, should be very selective and compressed. 4
Neighbor AP info
references in : 1) Neighbor report element, in Figure ). Beacon timing IE, page 695, section ; for neigbhor's next becon Tx time; 3). AP channel report IE, page 580, section
13+ per neighbor
yes, should be designed in a very compressed way.
Variable, 3*n; n is the number of neighbors
Lei Wang, InterDigital Communications

14. Discussions about FILS Discovery (FD) Frame Contents
July 2012
Discussions about FILS Discovery (FD) Frame Contents
Basic FD Frame Functions vs. Required Info Contents:
Advertize the presence of the AP on the channel:
BSSID, SSID, Channel descriptors, e.g., Country, Operation class, and Operation channel
Synchronize the STAs
Timestamp for Time Synchronization Function (TSF)
Provide necessary information for a fast AP/Network selection
Capabilities; Time to next TBTT; BSS load; Security; Access Network options; neighbor info; etc.
Provide necessary information to enable STA to transmit
PHY specific parameters; power constraint; etc.
FD frame information content selection considerations :
Minimize the mandatory info contents, e.g., only the AP presence parameters are mandatory;
Include additional info contents in a flexible and incremental way.
A summary of FD frame content discussion is provided in next two slides;
more details can be found in the Appendix section of this contribution.
Lei Wang, InterDigital Communications

15. Summary of FILS Discovery Frame Content Considerations
July 2012
Summary of FILS Discovery Frame Content Considerations
Index
Information
description / Notes
size (bytes)
mandatory / optional 1
compressed SSID
The SSID element indicates the identity of an ESS or IBSS. 4
mandatory 2
Short Timestamp
used for Time Synchronization Function (TSF)
Optional 3
Condensed Country string
uses the same 2-byte condensed country string as in MP frame; although 3 bytes in dot11CountryString
operation class
indicates the operating class value for the operating channel, as defined in Annex E. 5
operation channel
indicates the operating channel, as defined in Annex E. 6
power constraints
the information necessary to allow a STA to determine the local maximum transmit power in the current channel.
optional 7
time of next TBTT
Informs the STA of the arrival time of the next full beacon, an offset value in unit of Tus from the FD frame Tx time 8
Access network options
indicate access services provided by AP/Network 9
FILS Discovery (FD) Interval
basic periodicity of FILS Discovery frames, in units of TUs (i.e., 1024us)
Lei Wang, InterDigital Communications

16. Summary of FILS Discovery Frame Content Considerations -- Con’t
July 2012
Summary of FILS Discovery Frame Content Considerations -- Con’t
Index
Information
description / Notes
size (bytes)
mandatory / optional 10
Capability
used to indicate requested or advertised capabilities; covering critical initial link setup capabilities, based on MP capability and beacon/probe response capability, further capability considerations, e.g., IPv4/IPv6, etc. 2
optional 11
PHY Info
PHY specific parameters, e.g., ** 11g PHY, 1 byte as used in ERP IE in beacon frame; page 487, **11n PHY, current HT operation IE, HT capability IE, Overlapping BSS scan IE, and 20/40 coexistence IE
variable 12
Security info
indicate security related capabilities, and further security info that requires early provisioning, e.g., info abstracted from the current RSNE 4 13
BSS load Info
Compressed indication of the BSS load info, e.g., average access delay and/or Channel utilization 1 14
Neighbor AP info
provide a list of neighbor APs/Channels and their TBTTs, e.g., just list the channel class / channel number and next beacon time.
Variable 15
Other optional IEs
used to include other additional IEs
Lei Wang, InterDigital Communications

17. Discussions about FD Frame Contents and Relevant Procedures
July 2012
Discussions about FD Frame Contents and Relevant Procedures
Enabling multiple use cases with optional FD frame content items
Example-1: the FD frame body contains a minimum set of info, e.g., only the info for advertising the presence of AP and the info of next TBTT, which enables STA:
To decide whether waiting for the regular beacon or switching to scan another channel and then coming back to receive beacon at the proper time; and
To minimize the needs of sending probe request with wildcard SSID.
Example-2: the FD frame body contains enough info for STA to initiate association, which enables STA
to complete the scanning of the channel without waiting for beacon or sending probe request.
Example-3: the FD frame body contains a minimum set of info plus neighbour APs’ next TBTTs, which enables STA :
to optimally schedule the scanning of multiple channels/APs by minimizing the total waiting time for scanning the multiple channels.
Lei Wang, InterDigital Communications

18. Discussions about FD Frame Contents and Relevant Procedures – Con’t
July 2012
Discussions about FD Frame Contents and Relevant Procedures – Con’t
The flexible inclusions of FD frame body contents:
Allows AP to decide what information to carry in FD frames, based on certain real-time factors, e.g., traffic loading, percentage of medium time consumed by FD frames; etc.
Enables STA to decide what to do next, depending on the available info in a received FD frame, e.g., switching to another channel, initiating association, etc.
Lei Wang, InterDigital Communications

19. July 2012
Straw-Polls
Straw-Poll-1: Do you support including the following information items in the FILS Discovery Frame body?
Compressed SSID
Condensed Country String
Operation Class
Operation Channel
Time of Next TBTT
Result Yes No Abstain_______________
Lei Wang, InterDigital Communications

20. July 2012
Straw-Polls
Straw-Poll-2: Do you support optionally including the following information items in the FILS Discovery Frame body?
Short Timestamp
Power Constraints
Access Network Options
FILS Discovery frame interval
Capability information
Security Information
BSS Load Information
PHY information
Neighbor AP information
Result Yes No Abstain_______________
Lei Wang, InterDigital Communications

21. Motions for Proposed Text for SFD
July 2012
Motions for Proposed Text for SFD
Motion-1: add the following text to Subsection “6.2.1 General Approach”, on page 8, in the TGai SFD, 12/0151r8
The FILS Discovery frame shall include the following information fields:
A Compressed SSID field
A Condensed Country String field
An Operation Class field
An Operation Channel field
A Time of Next TBTT field
Mover:
Seconder:
Result Yes No Abstain_______________
Lei Wang, InterDigital Communications

22. Motions for Proposed Text for SFD
July 2012
Motions for Proposed Text for SFD
Motion-3: add the following text to Subsection “6.2.1 General Approach”, on page 8, in the TGai SFD, 12/0151r8
The FILS Discovery frame may include the following information items:
Short Timestamp
Power Constraints
Access Network Options
FILS Discovery frame interval
Capability
Security Information
BSS Load Information
PHY information
Neighbor AP information
Mover:
Seconder:
Result Yes No Abstain_______________
Lei Wang, InterDigital Communications

23. References: IEEE Std 802.11™-2012
July 2012
References:
IEEE Std ™-2012
ai-call-for-contributions-to-the-tgai- specification-framework
ai-proposed-specification-framework-for-tgai
ai-passive-scanning-improvements-draft
ai-passive-scanning-improvements-ad-hoc- report
ai-FILS-Discovery-Frame-Format- Discussions
ah-specification-framework-for-tgah
ah-short-beacon
ah-short-beacon
Lei Wang, InterDigital Communications

24. July 2012
Appendix
Lei Wang, InterDigital Communications

25. Detailed Discussions about FD Frame Contents
July 2012
Detailed Discussions about FD Frame Contents
A fundamental question: what information items are needed for the FD frame’s basic functions:
Advertize the presence of the AP on the channel:
BSSID, SSID, Channel descriptors, e.g., Country, Operation class, and Operation channel
Synchronize the STAs
Timestamp for Time Synchronization Function (TSF)
Provide necessary information for a fast AP/Network selection
Capabilities; Time to next TBTT; BSS load; Security; Access Network options; neighbor info; etc.
Provide necessary information to enable STA to transmit
PHY specific parameters; power constraint; etc.
Lei Wang, InterDigital Communications

26. Information for Advertizing the presence of the AP on the channel
July 2012
Information for Advertizing the presence of the AP on the channel
BSSID: uniquely identifies each BSS
6-byte MAC address of the AP for an infrastructure BSS;
address-3 field in the MAC header of MAC management frame.
SSID: the identity of an ESS or IBSS
Currently in , encoded as IE with 0 to 32 bytes SSID field;
Compressed SSID: proposed in ah short beacon, 12/0129r3,
4-byte, Contains a representation of the SSID of the BSS
A device that knows the full SSID can discover the presence of the BSS by decoding the compressed SSID
Proposal: Compressed SSID should be a hash of the full SSID
Hashing function should be standardized
Question: Can the 11ah compressed SSID proposal be re-used for 11ai FILS Discovery frame?
Lei Wang, InterDigital Communications

27. July 2012
Information for Advertizing the presence of the AP on the channel – Con’t
Channel descriptors:
Country, Operation Class, and Operation Channel together specify the channel frequency and spacing for the operating channel.
Country string: identifying the country where the STA locates and operates.
3-byte parameter: dot11CountryString
Condensed Country string: first 2 bytes in dot11CountryString, used in Measurement Pilot frame.
Operation class: identifying the operation class for the operation channel
1-byte, as defined in Annex E in spec.
Operation channel: identifying the operation channel within the operation class
Lei Wang, InterDigital Communications

28. Information for Synchronizing STA
July 2012
Information for Synchronizing STA
Timestamp for Time Synchronization Function (TSF):
8-byte in beacon frame as specified in spec;
4-byte proposed for 11ah-short beacon, with the following reasons to support that 4 LSBs of the full TSF is Sufficient for maintaining synchronization
With a 4 byte time stamp rollover occurs every ~71 minutes
With a +/- 20 ppm drift for the clock, to drift by 30 min (~71/2) will take years
A sensor node can maintain time sync with its AP if it checks a short beacon as rarely as once a day
Question: is 4-byte Timestamp sufficient for 11ai FILS Discovery frame?
Lei Wang, InterDigital Communications

29. Information for Facilitating a Fast AP/Network Selection
July 2012
Information for Facilitating a Fast AP/Network Selection
Time to next TBTT
Indicating the arrival time of next regular beacon frame from the transmitting AP of the current FD frame;
1-byte, in unit of Transmission Unit (TU), i.e., 1024us;
Setting to the offset value referencing from the current FD frame transmission time.
Lei Wang, InterDigital Communications

30. Information for Facilitating a Fast AP/Network Selection – con’t
July 2012
Information for Facilitating a Fast AP/Network Selection – con’t
Capabilities:
What type of capability indications are needed in FD frame?
capabilities that assist STA for a fast AP/Network discovery
References: Multiple capability information items in Beacon / Probe Response, e.g., Capability information field, Extended Capability IE, etc.
Capability indications considered in FD frame:
PHY capability indications: should be considered as part of PHY info?
Short Preamble, PBCC,
Security capability indications: should be considered as part of security info?
ESS indicator
Short slot time
Spectrum Management
IPv4/IPv6
????
Lei Wang, InterDigital Communications

31. Information for Facilitating a Fast AP/Network Selection – con’t
July 2012
Information for Facilitating a Fast AP/Network Selection – con’t
BSS load information
indicating the level of traffic loading at the BSS
5 relevant IEs in spec:
BSS load IE: 2+5 bytes, containing the info of
STA count: the total number of STAs currently associated with this BSS;
Channel utilization: the percentage of time, linearly scaled with 255 representing 100%, that the AP sensed the medium was busy;
Admission Capability: the remaining amount of medium time available via explicit admission control, in units of 32 μs/s.
BSS Available Admission Capacity IE: 2+2+2*n bytes, containing the info of Admission Capabilities for each UP/AC (User Priority / Access Category);
QoS Traffic Capability IE: 2+1+m bytes, containing the info of STA counts for each UP/AC ;
BSS Average Access Delay IE: 2+1 bytes, containing the info of a scalar indication of average medium access delay;
BSS AC Access Delay IE: 2+4 bytes; containing the info of Access Delay for each UP/AC.
Lei Wang, InterDigital Communications

32. Information for Facilitating a Fast AP/Network Selection – con’t
July 2012
Information for Facilitating a Fast AP/Network Selection – con’t
BSS load information – Con’t
Question: do we need this many different BSS load related IEs in the 11ai FILS Discovery frame? Answer: No, not at all!
What is it really needed in FD frame regarding BSS load?
An indication of how busy the AP is, i.e., the level of loading at the AP;
One or two parameters should be sufficient, e.g., ;
Average access delay: 1-byte info; specified in Section in ;
Channel utilization: 1-byte info; specified in Section in
Can we define an 1-byte data to indicate the BSS load info? Yes!
It can be one parameter, e.g., Average Access Delay;
Or, it can contain two parameters, e.g.,
5 bits for Average Access Delay
3 bits for channel utilization
Lei Wang, InterDigital Communications

33. Information for Facilitating a Fast AP/Network Selection – con’t
July 2012
Information for Facilitating a Fast AP/Network Selection – con’t
Security info
Security info in Beacon and Probe Response:
RSNE: Robust Security Network Element
Privacy capability indication in the Capability info field
Any additional security info considerations:
FILS Fast-EAP based authentication
FILS EAP-RP based authentication
FILS Non-EAP Fast authentication
What else?
Questions:
What security info should be included in the FD frame?
Is it possible to have a fixed-size security info field, e.g., 4-byte field, in the FD frame?
Lei Wang, InterDigital Communications

34. Information for Facilitating a Fast AP/Network Selection – con’t
July 2012
Information for Facilitating a Fast AP/Network Selection – con’t
Access Network options:
indicates access services provided by AP/Network ;
1-byte info as defined in Figure 8-352, in spec, also adopted in ah short beacon.
Lei Wang, InterDigital Communications

35. Information for Facilitating a Fast AP/Network Selection – con’t
July 2012
Information for Facilitating a Fast AP/Network Selection – con’t
Neighbor AP Info
Provide info of the neighbor APs/Channels;
What info should be included for each neighbor AP?
Channel class: 1-byte, as defined in Annex E; assume the same country string as the transmitting AP;
Channel number: 1-byte, as defined in Annex E;
Next TBTT: 1-byte, an offset value in unit of TUs referencing from this FD frame transmission time;
BSSID or SSID: do we really need this info? Debatable!
Example of the Neighbor AP IE in FILS Discovery frame:
Lei Wang, InterDigital Communications

36. Information for Enabling STA to Transmit
July 2012
Information for Enabling STA to Transmit
Question: when a STA can receive and decode FD frame, how much PHY and RF channel information does it have already before reading any contents in the FD frame?
Dot11 system is TDD, i.e., Rx and Tx on the same channel, therefore, there should be some channel info obtained through the reception of FD frame or Beacon frame.
The PHY header must also contains some info about PHY, e.g., PHY type,
PHY specific info:
11g: 1 byte info body in the ERP IE,
11n: HT capability IE; HT operation IE; 20/40 coexistence IE; Overlapping BSS scan IE;
11ac: VHT Capabilities; VHT Operation; VHT Transmit Power Envelope element;
Power Constraint
One IE in current Beacon and Probe Response frame, with 1 byte info body.
Lei Wang, InterDigital Communications

37. Information for Enabling STA to Transmit – con’t
July 2012
Information for Enabling STA to Transmit – con’t
PHY specific info:
11g: 1 byte info body in the ERP IE, with only 3 bits actually used. B0 B1 B2 B3 B4 B5 B6 B7
Bits
Reserved
Barker_Preamble_Mode
NonERP_Present
Use_Protection
Questions:
Are the PHY capability indications in the current Capability field, e.g., short preamble, PBCC, applied to 11g?
If so, can we use the current reserved bits in the ERP info body for those PHY capability indications?
Lei Wang, InterDigital Communications

38. Information for Enabling STA to Transmit – con’t
July 2012
Information for Enabling STA to Transmit – con’t
PHY specific info – Con’t
11n: multiple IEs in Beacon and Probe Response based on
HT capability IE:
26-byte info body;
could be cut down to 1-byte info body, in FD frame, as defined in next slide.
HT operation IE:
22-byte info body;
could be cut down to 1-byte info body, i.e., the Primary Channel field, in FD frame
20/40 coexistence IE: variable-size info body; not needed in FD frame;
Overlapping BSS scan IE: 14-byte info body; not needed in FD frame.
2-byte info body for11n PHY Specific Info in FD frame:
1-byte for Short HT capability
1-byte for Primary Channel.
Lei Wang, InterDigital Communications

39. Information for Enabling STA to Transmit – con’t
July 2012
Information for Enabling STA to Transmit – con’t
PHY specific info – Con’t
Short HT Capability Information Field:
HT Capability Item
Size (bits)
Supported Channel Width Set 1
HT-Greenfield
Tx STBC
Rx STBC 2
Reserved
40 MHz Intolerant
HT PHY Info in FD Frame:
Bits B0 B1 B2 B3 B4 B5 B6 B7 B8
B15
TX STBC
RX STBC
Reserved
Primary Channel
40 MHz Intolerant
Supported Channel Width Set
HT-Greenfield
Lei Wang, InterDigital Communications

40. Information for Enabling STA to Transmit – con’t
July 2012
Information for Enabling STA to Transmit – con’t
PHY specific info:
11ac: multiple IEs in Beacon frame and Probe Response frame based on P802.11ac/D3.0, e.g.,
VHT Capabilities element: 12 bytes for info fields;
VHT Operation element: 5 bytes for info fields;
VHT Transmit Power Envelope element: 2 to 5 bytes for info fields;
What’re needed in FILS Discovery frame for 11ac PHY specific?
Lei Wang, InterDigital Communications

41. Information for Enabling STA to Transmit – Con’t
July 2012
Information for Enabling STA to Transmit – Con’t
Power Constraint
Power Constraint IE in Beacon and Probe Response frame,
1 byte info body;
contains the information necessary to allow a STA to determine the local maximum transmit power in the current channel.
Questions:
do we really need this parameter in the FD frame?
If so, should it be part of the PHY specific info?
Lei Wang, InterDigital Communications

42. Detailed Discussions about FD Frame Contents – con’t
July 2012
Detailed Discussions about FD Frame Contents – con’t
Other Optional IEs ?
?????
Lei Wang, InterDigital Communications