Simplification of Enablement Procedure for TVWS band

1. Simplification of Enablement Procedure for TVWS band Date: March 11, 2011 Authors:

2. Contents • Introduction • Review of Enablement Procedure in 802.11af D1.0 • Dependent STA, Enabling STA and Enabling Signal • Enablement Procedure in TVWS band • Network Architecture and Interfaces • Backup slides • Summary of FCC Rules

3. Introduction • The Dynamic Station Enablement (DSE) from 802.11y amendment has been adopted to 802.11af as a basis for controlling client stations • However, there are many different requirements on network initiation and operation in TVWS band compared to licensed operation in 3650-3700 MHz band for which the existing DSE procedures were first introduced • In the current 802.11af draft D1.0, the scope of DSE enablement and other DSE procedures for TVWS band are not very clear. There are some conflicts in required behaviours/rules for various entities like enabling STA, registered STA and dependent STA. • We believe, the task group should revisit the enablement requirements, along with reference architecture on entities, terms and definitions. • It may be better to only keep the common DSE procedure details applicable for 3650 or TVWS band in clause 10.12, and detailed band specific text moved to Annexes. • The enabling and dependent STAs behaviours in TVWS band should more closely resemble to FCC’s TVWS rules as a basis

4. Review and discussion on enablement procedure • Current 802.11 baseline describes the Dynamic Station Enablement (DSE) by using enabling STA and dependent STA terms, but also the registered STA and Fixed STA are used. In short: • Enabling STAs are registered STAs allowed to enable other non-registered dependent STAs to operate but with hooks of DSE control procedures (DSE enablement/deenablement, enabling signal over the air) • All Fixed STA and enabling STA are required to have their operating locations registered, and thus are registered STAs. They both broadcast their registered location information • Fixed STAs operate in standalone manner, they are not allowed to enable other dependent STAs • Current clause 10.12 is very much tied with regulatory specific rules for US 3650-3700 MHz band. The recent changes in .11af D1.0 for accommodating TVWS band operation looks far less from being complete: • There are some major and many subtle differences • It is not clear if .11af should try to decouple and put together in separate regulatory specific clause or can still amend the existing text

5. Dependent STA, Enabling STA and Enabling Signal • Let’s review first the definitions and behaviors of dependent STA, enabling STA and Enabling signal: • Dependent station (STA): A STA that is not registered and whose operational parameters are dictated by messages it receives from an enabling STA. Once enabled by the dynamic STA enablement (DSE) process, a dependent STA's continued operation becomes contingent upon being able to receive messages from its enabling STA over the air. • Works fine for TVWS context as well, except the last sentence could be confusing as a Mode I TVBD is also contingent upon receiving contact verification signal • In general, what does the word “dependent” means in .11af context? • Is the dependency for initiating the first transmission in TVWS band, i.e., a device require to hear an enabling signal in order for it to get a list of available channels? • If so, Mode II or Fixed can also be a dependent STA (or dependent AP) until it receives its own channel list • Mode I becomes dependent STA for enabling signal unless it completes initial contact • Or, is the dependency for obtaining a list of valid channels without having its own geo-location (CVS dependency)? • A Mode I is always dependent on its master from which it receives a list of available channels • .11y dependent STA behaviour fits (like 60 s over the air signal reception) except some adjustments needed

6. Dependent STA, Enabling STA and Enabling Signal .. • Enabling station (STA): A registered STA that has the authority to control when and how a dependent STA can operate. An enabling STA communicates an enabling signal to its dependents over the air. An enabling STA may choose for other dynamic STA enablement (DSE) messages to be exchanged over the air, over the distribution system (DS), or by mechanisms that rely on transport via higher layers. • What is the key function of “enabling STA” in TVWS band ? • .11y specific reasoning was for both: to transmit enabling signal (with registered location) and also to do enablement/deenablement of dependent STAs • What about regulatory requirements like obtaining valid channel list? • Enabling Signal: • No definition as such in the baseline, except rules like “An enabling STA communicates an enabling signal to its dependents over the air” • .11af has added an inband enabling signal for TVWS purpose. The “over the air” is limited to TVWS band • More clarity in Enabling signal and contact verification signal for the purpose of DSE is needed (esp how these can be related for DSE procedures)

7. Enabling Signal, CVS and FCC Rules • Enabling signal/control signal/contact seeking signal look very similar • In § 15.202 Certified operating frequency range.“ For the purposes of this section, a master device is defined as a device operating in a mode in which it has the capability to transmit without receiving an enabling signal. In this mode it is able to select a channel and initiate a network by sending enabling signals to other devices.” • In § 15.703 (c) Fixed devices “ A fixed TVBD may select channels for operation itself from a list of available channels provided by a TV bands database, initiate and operate a network by sending enabling signals to one or more fixed TVBDs and/or personal/portable TVBDs.” • In § 15.703 (g) Network initiation. “The process by which a fixed or Mode II TVBD sends control signalsto one or more fixed TVBDs or personal/portable TVBDs and allows them to begin communications” • In § 15.711 (b) (3) (iv), “To initiate contact with a fixed or Mode II device, a Mode I device may transmit on an available channel used by the fixed or Mode II TVBD or on a channel the fixed or Mode II TVBD indicates is available for use by a Mode I device on a signal seeking such contacts.” • What can be concluded about Enabling Signal? • Only a master device that has already obtained valid list of channels from database can transmit it • Devices not able to get channel list without using TVWS transmission must hear enabling signal first • Fixed or Mode II may use it to access Internet indirectly via another Fixed/Mode II TVBD • Mode I device can initiate contact with Mode II/Fixed • Once a device receive valid channel list, there is no need to hear enabling signal

8. Enabling Signal, CVS and FCC Rules .. • Contact Verification Signal: • In § 15.703 (b)Contact verification signal: “An encoded signal broadcast by a fixed or Mode II device for reception by Mode I devices to which the fixed or Mode II device has provided a list of available channels for operation. Such signal is for the purpose of establishing that the Mode I device is still within the reception range of the fixed or Mode II device for purposes of validating the list of available channels used by the Mode I device and shall be encoded to ensure that the signal originates from the device that provided the list of available channels. A Mode I device may respond only to a contact verification signal from the fixed or Mode II device that provided the list of available channels on which it operates. A fixed or Mode II device shall provide the information needed by a Mode I device to decode the contact verification signal at the same time it provides the list of available channels.” • §15.711 (b) (3) (iv) Mode I Operation: “At least once every 60 seconds, except when in sleep mode, i.e., a mode in which the device is inactive but is not powered-down, a Mode I device must either receive a contact verification signal from the Mode II or fixed device that provided its current list of available channels or contact a Mode II or fixed device to re-verify/re-establish channel availability. A Mode I device must cease operation immediately if it does not receive a contact verification signal or is not able to re-establish a list of available channels through contact with a fixed or Mode II device on this schedule.” • § 15.711 (f) (iii) Security: “Contact verification signals transmitted for Mode I devices are to be encoded with encryption to secure the identity of the transmitting device. Mode I devices using contact verification signals shall accept as valid for authorization only the signals of the device from which they obtained their list of available channels.”

9. Enabling Signal, CVS and FCC Rules .. • What can be concluded about Contact Verification Signal? • CVS is only required to be transmitted from a Mode II/Fixed device after it sends the list of available channel • Mode II/Fixed devices are enforcing valid geo-graphic boundary for operation with legally available channels • The periodic reception requirement by Mode I devices is similar to enabling signal requirement in .11y DSE (at least once every 60 s) • Current Dependent STA state machine in 10.12.5 is described in terms of “Enabling Signal”. CVS is different than enabling signal, thus, need to replace the state diagram for TVWS operation • Background from January pre-meeting: General agreement that an enabling signal to meet regulatory requirements is orthogonal to DSE enablement, and orthogonal to the management of Mode I client devices after they have received a white spaces map • Is the intent here is to remove dependency of “Enabling Signal” and “contact verification signal” from DSE enablement? • Are we trying to decouple DSE enablement from regulatory requirements? .11y DSE rules looks quite closely related to 3650 MHz regulatory requirements

10. Enablement Procedure in TVWS band • White space enablement can be simplified, but what changes are necessary? • Requirement to hear enabling signal should only be necessary when a TVBD needs to transmit in TVWS band for the purpose of obtaining available channel list • Personal/portable TVBDs in Client mode (Mode I) need to hear contact verification signal transmitted directly from a Fixed or Mode II personal/portable device once at least every 60 s, i.e., the rules to continue hearing enabling signal should be replaced by the need to hear CVS • DSE operational control (such as periodic reception of certain signals, measurement obligations, channel/power commands etc) should only be required for TVBDs not having their own available channel list (i.e., not capable to operate as Master devices/not having their own geo-location) • What could be sufficient for enablement in TVWS band? • Dependent STA must hear enabling signal if it requires to transmit in TVWS band before it can obtain a list of available channels • i.e., enabling signal may not be needed if channel list can be acquired using some other band • Dependent STA sends CAQ Request • The enabling STA may perform authentication of the dependent STA (FCC ID verification result) • The enabling STA sends response to CAQ request with valid available channel list • Continue receiving CVS once at least every 60 s (all PP clients must hear CVS) • Perform channel and power changes as required by the master device.

11. Enablement Procedure in TVWS band .. • Apart from the above requirements, do we additionally need DSE Enablement step? • Is the DSE Enablement necessary before obtaining channel list (channel availability query)? • Is DSE Enablement can be done before any authentication, in pre-associated state (as assumed for public action frame or GAS)? • The control of Mode I device is already enforced by means of secure initial contact with Mode II/Fixed device and subsequent periodic contact verification signal rules. Are there any added benefits from DSE enablement step? • Other Issues: • The DSE enablement procedure for a dependent AP and dependent STA can be differentiated: • A dependent AP may initially operate as a client device to access internet via another AP. However, once it can obtain its own channel list for operation, it no longer needs to be under the control of another STA. • Any dependent STAs without its own geo-location capability, however, remains dependent throughout • A fixed TVBD may either operate as a Master or a Client station, but both must always obtain their valid channel list from geo-location database. Client need only the enabling signal, but no DSE

12. Network Architectures and Interfaces Scenario 2: AP does not have direct connection to Internet, access is via another TVBD Scenario 1: AP has direct connection to Internet for DB access

13. Network Architectures and Interfaces.. What about the above scenario ?

14. Miscellaneous Comments on Clause 10.12 • Dependent station does not have to report the LCI of its enabling STA in TVWS band • A dependent STA does not have to transmit “DSE Registered Location Announcement” frame to advertise the registered location of its enabling STA • Enabling STA may not be registered STA if they are personal/portable Mode II devices\ • All dependent STA do not have to set: dot11LCIDSERequired and dot11LCIDSEImplemented, if they are not capable to determine their geo-location coordinates on their own. • Based on current REVmb, when dot11LCIDSERequired is set, Beacon frames, probe response and association response frame contains DSERegisteredLocation element. However, this is not necessary for dependent STAs in TVWS band • In TVWS band, only Fixed STA require to broadcast their ID and location information, not all registered STAs

15. Backup Slides

16. Summary of FCC Rules (for network initiation and operation) Fixed Device operation: • Network Initiation: can initiate and operate network (can send enabling signal to other Fixed and PP TVBDs), but only after getting the channel list (for its own location) • Geo-location capability: • requires latitude, longitude coordinates (accuracy +/- 50 m) plus antenna height obtained by, • Own geo-location capability • Professional installation service • Need to determine at the time of installation and first activation from power-off, then re-establish each time if its location has been changed • Registration to FCC DB: • Required to register: first time after installation, then each time if its location has been changed • Detailed location and identifying information are required: • Geo-location coordinates plus antenna height above ground level • FCC ID, serial number by manufacturer, details of owner and responsible contact person

17. Summary of FCC Rules .. • Database access for channel query: • Access by connecting to the internet: either directly or through another fixed TVBD that has a direct connection to the Internet • Provides: location and identifying information • Receives: available channel list, channel availability schedule info for next 48 hours, may receive separate available channel list for Mode I. • At least once a day • Other functions during operation: • Must adjust the channel usage to comply with the channel availability schedule info obtained by the database for the 48 hour period since the time of last DB access • Must transmit identification signal (device identity and geo-location) • May accept contact initiation request from Mode I devices, and provide list of available channels (list valid for its own location or a separate list for Mode I obtained from DB) • Requires to first provide FCC ID of Mode I device and receive successful verification back • Must broadcast contact verification signal if it had provided a list of available channels for operation to a Mode I device • must have the capability to display the lists of available channels and operating channels

18. Summary of FCC Rules .. Personal/Portable Mode II Device: • Network Initiation: can initiate and operate network (can send enabling signal to other Fixed and PP TVBDs), but only after getting the channel list (for its own location) • Geo-location capability: • requires latitude, longitude coordinates (accuracy +/- 50 m) by its own geo-location capability • Need to determine its geographic position: • each time after activation from power-off • re-establish at least once every 60 s during operation (except while in sleep mode) • Registration to FCC DB: not required • Database access for channel query: • Access by connecting to the internet: either directly or through another fixed or Mode II TVBD that has a direct connection to the Internet • Provides: location (geographic latitude, longitude coordinates, accuracy +/- 50 m) and identifying information (FCC ID & Serial number by manufacturer) • Receives: • available channel list, may also receive channel availability schedule info for 48 hr • May request and receive channel availability information for multiple locations

19. Summary of FCC Rules .. • How often: • At least once a day, each time after activation from power-off • Once it moves by > 100 m distance since the location of last DB access, OR when moves outside from its currently valid channel availability zone for multiple locations • Other functions during operation: • Must adjust the channel usage to comply with the channel availability schedule information • May accept contact initiation request from Mode I devices, and provide list of available channels • Requires to first provide FCC ID of Mode I device and receive successful verification back from database • Must broadcast contact verification signal if it had provided list of available channels for operation to a Mode I device • Must signal Mode I devices to acquire new channel list if it looses power and obtains new channel list • must have the capability to display the lists of available channels and operating channels

20. Summary of FCC Rules .. Personal/Portable Mode I Device: • Network Initiation: not allowed to initiate a network of other Fixed or PP TVBDs • Geo-location capability: not required • Registration to FCC DB: not required • Database access for channel query: • Not required, but must be in contact with a fixed/Mode II device to get available channel list • Contact establishment with a Fixed or Mode II device for channel query: • To initiate contact, it can transmit in an available channel used by Fixed or Mode II device, or on a channel indicated to be available for Mode I device on a signal seeking such contacts • Provides: identifying information (FCC identifier) • Receives: available channel list and info to decode the contact verification signal • Contact verification process: • Must re-check/re-establish contact with a Fixed or Mode II device if activated from power-off • Must either receive and decode contact verification signal, at least once every 60 s (except while in sleep mode) originated from the same Fixed or Mode II device that had provided the current available channel list , OR contact a Mode II or fixed device to re-check/re-establish channel availability • Must seize operation immediately if it can not perform the procedure above • Other functions during operation: • must have the capability to display the lists of available channels and operating channels