Doc.: IEEE 802.11-08/0947r0



IEEE P802.11

Wireless LANs

|Normative Text for AP Power Down Notification |

|Date: 2008-09-xx |

|Name |Company |Address |Phone |email |

|Allan Thomson |Cisco Systems |170 W. Tasman Drive, San Jose, |+1-408-853-5570 |allant@ |

| | |CA95134 | | |

[pic]

7.3.2.37 Neighbor Report element

Insert the new rows and change the Reserved rows in Table 7-43b in 802.11k Draft 13.0 as follows:

|Table 7-43b—Optional Sub-element IDs for Neighbor Report |

|Sub-element ID |Name |Length field |Extensible |

| | |(octets) | |

|0 |Reserved | | |

|1 |TSF Information |4 |Yes |

|2 |Condensed Country String |2 |Yes |

|3 |BSS Transition Candidate Preference |1 | |

|4 |Power Down Duration |12 | |

|54-10 |Reserved | | |

|11 |BSS Load |7 | |

|312-65 |Reserved | | |

|66 |Measurement Pilot |1 to 238 |Sub-elements |

| |Transmission Information | | |

|67 |BSS Available Admission Capacity |4 to 28 |Yes |

|67-69 |Reserved | | |

|70 |RRM Enabled Capabilities |4 |Yes |

|71 |Multiple BSSID |1 to 238 |Sub-elements |

| |Traffic Generation |1 to 3 | |

|72+1-220 |Reserved | | |

|221 |Vendor Specific |1 to 238 | |

|222-255 |Reserved | | |

Insert the following text at the end of 7.3.2.37 in 802.11k Draft 13.0 as indicated below:

The BSS Transition Candidate Preference sub-element is optionally present in a Neighbor Report element included in a BSS Transition Management Request frame, as defined in 7.4.11.8. The format of the BSS Transition Candidate Preference sub-element field is shown in Figure 7-112g1.

| | | | |

| |Sub-element ID |Length |Preference |

|Octets: |1 |1 |1 |

| |

|Figure 7-112g1— BSS Transition Candidate Preference sub-element field format |

The value of the BSS Transition Candidate Information sub-element length field is 1.

The Preference field indicates the network preference for BSS transition to the BSS listed in this BSS Transition Candidate List Entries field in the BSS Transition Management Request frame. The Preference value is a number ranging from 0 to 255, as defined in Table 7-43b1, indicating an ordering of preferences for the BSS transition candidates for this STA. Additional details describing Preference are provided in 11.20.9.3.

|Table 7-43b1—Preference field values |

|Preference field value |Description |

|0 |Excluded AP |

|1-255 |Relative values used to indicate the |

| |preferred ordering of BSSs, with 1 as the |

| |highest order of preference. |

The BSS Available Admission Capacity sub-element is optionally present in the Neighbor Report element included in the BSS Transition Management Request frame. The format of the BSS Available Admission Capacity sub-element has the same format as the BSS Available Admission Capacity element (see 7.3.2.43).

The BSS Load sub-element is optionally present in the Neighbor Report element included in the BSS Transition Management Request frame. The format of the BSS Load sub-element has the same format as the BSS Load element (see 7.3.2.28).

The Traffic Generation sub-element is optionally present in the Neighbor Report element included in the BSS Transition Management Request frame. The format of the Traffic Generation sub-element has the same format as the Traffic Generation element (see 7.3.2.73).

The Power Down Duration sub-element is optionally present in a Neighbor Report element included in a BSS Transition Management Request frame, as defined in 7.4.11.8. The format of the Power Down Duration sub-element field is shown in Figure 7-112g2.

| | | | | |

| |Sub-element ID |Length |Power Down TSF |Duration |

|Octets: |1 |1 |8 |2 |

| | | | |

|Figure 7-112g2— Power Down Duration sub-element field format | | | |

The value of the Power Down Duration Information sub-element length field is 10.

The Power Down TSF field indicates the value of the TSF counter when the power down will occur in the future. A Power Down TSF field value of 0 indicates that the power down will occur imminently. Prior to power down, all associated STAs will be disassociated from the AP.

The Duration field is an unsigned 2 octet integer that indicates the number of minutes for which the BSS is not present. The Duration field value is set to 65535 when the AP is powering down for a period longer than or equal to 65535 minutes.

7.4.11.8 BSS Transition Management Request frame format

The BSS Transition Management Request frame uses the Action frame body format and is transmitted by an AP STA in response to a BSS Transition Management Query frame, or autonomously. The format of the BSS Transition Management Request frame body is shown in Figure v81.

| | | | | | | | | |

| |Category |Action |Dialog Token |Request mode |Disassociation |Validity |Power Down Duration |BSS Transition |

| | | | | |Timer |Interval |(optional) |Candidate List |

| | | | | | | | |Entries |

|Octets: |1 |1 |1 |1 |1 |1 |0 or 12 |variable |

| | | | | | | | |

The Category field is set to the value indicating the Wireless Network Management category, as specified in Table 24 in 7.3.1.11.

The Action field is set to the value indicating BSS Transition Management Request frame, as specified in Table v34 in 7.4.11.

The Dialog token field is set to the nonzero value received in the BSS Transition Management Query frame if the BSS Transition Management Request frame is being transmitted in response to a BSS Transition Management Query frame. If the BSS Transition Management Request frame is being transmitted, but not in response to a BSS Transition Management Query frame, the Dialog token field is set to a nonzero value chosen by the AP STA sending the BSS Transition Management Request frame to identify the request/response transaction.

The Request mode field is defined in Figure v82.

| | | | | | |

| |Preferred Candidate List Included |Abridged |Disassociation |Power Down |Reserved |

| | | |Imminent |Included | |

|Bit: |0 |1 |2 |3 |43 - 7 |

| | | | | |

|Figure v82—Request Mode field | | | | |

— The Preferred Candidate List Included (bit 0) field indicates whether the BSS transition candidate list included in this frame is a preferred candidate list or a list of known BSS transition candidates. See 11.20.8.3.

— The Abridged (bit 1) field indicates to the recipient of the frame the intended treatment of all BSSIDs not listed in the BSS Transition Candidate List. See 11.20.8.3.

— — The Disassociation Imminent (bit 2) field indicates whether the STA will be disassociated from the current AP. See 11.20.8.3.

— The Power Down Included (bit 3) field indicates that the Power Down Duraction fieldsub-element is included, the AP is shutting down and the STA will be disassociated.

The Disassociation Timer field is set to the number of beacon transmission times (TBTTs) until the serving AP sends a Disassociation frame to this STA. If the Disassociation Imminent field is set to 0, the Disassociation Timer field is reserved.

The Validity Interval field is set to the number of beacon transmission times (TBTTs) until this recommendation of this BSS transition candidate is no longer valid. A value of 0 is reserved.

The Power Down Duration field contains the Power Down Duration sub-element (see 7.3.2.37) for the current BSS and is present only when the Power Down Included field is set to 1 in the Request mode field.

The BSS Transition Candidate List Entries field contains one or more Neighbor Report elements described in 7.3.2.37. If the STA has no information in response to the BSS Transition Management Query frame, the Neighbor Report Elements are omitted. The length of the BSS Transition Candidate List Entries in a BSS Transition Management Request frame is limited to 2304 octets.

7.4.11.9 BSS Transition Management Response frame format

The BSS Transition Management Response frame uses the Action frame body format and is optionally transmitted by a STA in response to a BSS Transition Management Request frame. The format of the BSS Transition Management Response frame body is shown in Figure v83.

| | | | | | | |

| |Category |Action |Dialog Token |Status code |Power Down Delay |Target BSSID |

| | | | | | |(Optional) |

|Octets: |1 |1 |1 |1 |1 |0 or 6 |

| | | | | | | |

|Figure v83— BSS Transition Management Response frame body format | | | | | | |

The Category field is set to the value indicating the Wireless Network Management category, as specified in Table 24 in 7.3.1.11.

The Action field is set to the value indicating BSS Transition Response, as specified in Table v34 in 7.4.11.

The Dialog Token field is set to the value in the corresponding BSS Transition Management Request frame. The BSS Transition Management Response frame is only transmitted in response to a BSS Transition Management Request frame.

The Status code field contains the status code in response to a BSS Transition Management Request as defined in Table v37. If the STA decides to roam to another BSS, then the status code is set to “Accept”. If the STA intends to remain the association with the current BSS, the status code is set to one of the “Reject” reason codes.

|Table v37—Status Code Definitions |

|Status Code |Status code description |

|0 |Accept |

|1 |Reject - Unspecified reject reason. |

|2 |Reject – Insufficient Beacon frames received from all|

| |candidates |

|3 |Reject – Insufficient available capacity from all |

| |candidates |

|4 |Reject – Power down undesired |

|5 |Reject – Power down delay requested |

|64-255 |Reserved |

The Target BSSID field is the BSSID of the BSS that STA transitions to. This field is not present if the STA does not transition or if no transition information is available.

The Power Down Delay field is set to the number of minutes the responding STA wishes the BSS to delay powering down for. This field is reserved if the Status code field value is not set to 5.

If the Status code field value is set to 5 (Reject-Power down delay requested) the Power Down Delay field is set to the number of minutes the responding STA wishes the BSS to delay powering down for. If the Status code field value is not set to 5 the Power Down Delay field is reserved.

10.3.52 BSS Transition Management

10.3.52.1 BSS Transition Management Procedure

The informative diagram shown in Figure v105 depicts the BSS Transition Management procedure and is not meant to be exhaustive of all possible protocol uses.

Figure v105—BSS Transition Management request — accepted

10.3.52.2 MLME-BTMQUERY.request

This set of primitives supports the signaling of BSS Transition Management Query frames between non-AP STAs and an AP.

10.3.52.2.1 Function

This primitive requests transmission of a BSS Transition Management Query frame to the AP with which the STA is associated.

10.3.52.2.2 Semantics of the Service Primitive

The primitive parameters are as follows:

MLME-BTMQUERY.request (

Peer MAC Address,

DialogToken,

BSSTransitionQueryReason)

|Name |Type |Valid range |Description |

|Peer MAC |MACAddress |Any valid individual|The address of the peer MAC entity to which the BSS |

|Address | |MAC Address |Transition Management Query frame is sent. |

|DialogToken |Integer |1 – 255 |The Dialog Token to identify this BSS Transition |

| | | |Management transaction. |

|BSSTransitionQuery |Integer |0 – 255 |As defined in 7.4.11.7. |

|Reason | | | |

10.3.52.2.3 When Generated

This primitive is generated by the SME to request that a BSS Transition Management Query frame be sent to the AP with which the STA is associated to initiate a BSS Transition Management procedure.

10.3.52.2.4 Effect of Receipt

On receipt of this primitive, the MLME constructs a BSS Transition Management Query management frame of action type. The STA then attempts to transmit the frame to the AP with which it is associated.

10.3.52.3 MLME-BTMQUERY.indication

10.3.52.3.1 Function

This primitive indicates that a BSS Transition Management Query frame was received from a non-AP STA.

10.3.52.3.2 Semantics of the Service Primitive

The primitive parameters are as follows:

MLME-BTMQUERY.indication (

Peer MAC Address,

DialogToken,

BSSTransitionQueryReason)

|Name |Type |Valid range |Description |

|PeerMAC |MACAddress |Any valid individual|The address of the non-AP STA MAC entity from which a |

|Address | |MAC Address |BSS Transition Management Query frame was received. |

|DialogToken |Integer |1 – 255 |The Dialog Token identifying this BSS Transition |

| | | |Management transaction as received in the BSS Transition|

| | | |Management Query frame. |

|BSSTransitionQuery |Integer |0 – 255 |The BSS Transition Query Reason Code in the BSS |

|Reason | | |Transition Management Query frame that was received. |

10.3.52.3.3 When Generated

This primitive is generated by the MLME when a valid BSS Transition Management Query frame is received.

10.3.52.3.4 Effect of Receipt

On receipt of this primitive the SME shall operate according to the procedure in 11.20.9.

10.3.52.4 MLME-BTM.request

10.3.52.4.1 Function

This primitive requests transmission of a BSS Transition Management Request frame to a non-AP STA.

10.3.52.4.2 Semantics of the Service Primitive

The primitive parameters are as follows:

MLME-BTM.request (

Peer MAC Address

DialogToken,

RequestMode,

DisassociationTimer,

BSSTransitionCandidateList)

|Name |Type |Valid range |Description |

|Peer MAC |MACAddress |Any valid individual|The address of the peer MAC entity to which the BSS |

|Address | |MAC Address |Transition Management Request frame is sent. |

|DialogToken |Integer |1 – 255 |The Dialog Token to identify the BSS Transition |

| | | |Management transaction. Set to 0 for an autonomous BSS |

| | | |Transition Management Request frame. |

|RequestMode |Integer |As specified in |Contains the Disassociation Imminent and Abridged bits |

| | |7.4.11.8 |for the BSS Transition Management Request. |

|Disassociation |Integer |0 – 255 |Specifies the number of TBTTs until the AP shall |

|Timer | | |disassociate the non-AP STA. A value of 0 indicates time|

| | | |of disassociation has not yet been determined and a |

| | | |value of 1 indicates disassociation shall occur before |

| | | |the next TBTT. |

|BSSTransition |Set of Neighbor |Set of Neighbor |Contains the description of candidate BSS transition APs|

|CandidateList |Report Elements |Report Elements as |and their capabilities as described in section 7.3.2.37.|

| | |defined in the | |

| | |Neighbor Report | |

| | |Element in 7.3.2.37 | |

10.3.52.4.3 When Generated

This primitive is generated by the SME to request that a BSS Transition Management Request frame be sent to an associated non-AP STA. This request is sent either following the reception of a MLME-BTMQUERY.indication or may be sent autonomously.

10.3.52.4.4 Effect of Receipt

On receipt of this primitive, the MLME constructs a BSS Transition Management Request management frame of action type. The STA then attempts to transmit this frame to the indicated non-AP STA.

10.3.52.5 MLME-BTM.indication

10.3.52.5.1 Function

This primitive indicates that a BSS Transition Management Request frame was received from the AP with which the STA is associated.

10.3.52.5.2 Semantics of the Service Primitive

The primitive parameters are as follows:

MLME-BTM.indication (

ResultCode,

PeerMACAddress,

DialogToken,

RequestMode,

DisassociationTimer,

BSSTransitionCandidateList)

|Name |Type |Valid range |Description |

|ResultCode |Enumeration |SUCCESS, |Indicates the result of the corresponding |

| | |INVALID_ |MLME-BTMQUERY.request. The ResultCode field is set to |

| | |PARAMETERS, |SUCCESS if the received BSS Transition Request frame is |

| | |TIMEOUT, |an unsolicited frame. |

| | |TRANSMISSION_FAILURE| |

| | |, | |

| | |UNSPECIFIED_ | |

| | |FAILURE | |

|Peer MAC |MACAddress |Any valid individual|The address of the MAC entity from which a BSS |

|Address | |MAC Address |Transition Management Request frame was received. |

|DialogToken |Integer |1 – 255 |The Dialog Token to identity this BSS Transition |

| | | |Management transaction as received in the BSS Transition|

| | | |Management Request frame. |

|RequestMode |Integer |As specified in |Contains the Disassociation Imminent and Abridged bits |

| | |7.4.11.8 |for the BSS Transition Management Request. |

|Disassociation |Integer |0 – 255 |Specifies the number of TBTTs until the AP shall |

|Timer | | |disassociate the non-AP STA. A value of 0 indicates time|

| | | |of disassociation has not been determined yet and a |

| | | |value of 1 indicates disassociation shall occur before |

| | | |the next TBTT. |

|BSSTransition |Set of Neighbor |Set of Neighbor |Contains the description of candidate BSS transition APs|

|CandidateList |Report Elements |Report Elements as |and their capabilities as described in 7.3.2.37. |

| | |defined in the | |

| | |Neighbor Report | |

| | |Element in 7.3.2.37 | |

10.3.52.5.3 When Generated

This primitive is generated by the MLME when a valid BSS Transition Management Request frame is received. This primitive is also generated when the MLME-BTMQUERY.request contains invalid parameters and when a timeout or failure occurs.

10.3.52.5.4 Effect of Receipt

On receipt of this primitive the SME shall operate according to the procedure in 11.20.9.

10.3.52.6 MLME-BTM.response

10.3.52.6.1 Function

This primitive requests transmission of a BSS Transition Management Response frame to the AP with which the STA is associated.

10.3.52.6.2 Semantics of the Service Primitive

The primitive parameters are as follows:

MLME-BTM.response (

Peer MAC Address

DialogToken,

StatusCode,

PowerDownDelay,

TargetBSSID)

|Name |Type |Valid range |Description |

|PeerMAC |MACAddress |Any valid individual|The address of the peer MAC entity to which the BSS |

|Address | |MAC Address |Transition Management Query frame is sent. |

|DialogToken |Integer |1 – 255 |The Dialog Token to identify the BSS Transition |

| | | |Management transaction. |

|StatusCode |Integer |0 – 255 |As defined in 7.4.11.9. |

|PowerDownDelay |Integer |0 – 255 |As defined in 7.4.11.9 |

|TargetBSSID |MACAddress |Any valid individual|The BSSID of the BSS that the STA decided to roam to. |

| | |MAC Address |Field shall be null if STA decided not to roam. |

10.3.52.6.3 When Generated

This primitive is generated by the SME to request that a BSS Transition Management Response frame be sent to the AP with which the STA is associated.

10.3.52.6.4 Effect of Receipt

On receipt of this primitive, the MLME constructs a BSS Transition Management Response management frame of action type. The non-AP STA then attempts to transmit this to the AP with which it is associated.

10.3.52.7 MLME-BTM.confirm

10.3.52.7.1 Function

This primitive reports the results of a BSS Transition Management attempt with a specified peer MAC entity that is within an AP.

10.3.52.7.2 Semantics of the Service Primitive

The primitive parameters are as follows:

MLME-BTM.confirm (

ResultCode,

Peer MAC Address,

DialogToken,

BSSTransitionQueryReason,

StatusCode,

PowerDownDelay,

TargetBSSID)

|Name |Type |Valid range |Description |

|ResultCode |Enumeration |SUCCESS, |Indicates the result of the corresponding |

| | |INVALID_ |MLME-BTM.request. |

| | |PARAMETERS, | |

| | |TIMEOUT, | |

| | |TRANSMISSION_FAILURE| |

| | |, | |

| | |UNSPECIFIED_ | |

| | |FAILURE | |

|Peer MAC |MAC Address |Any valid individual|The address of the non-AP STA MAC entity from which a |

|Address | |MAC Address |BSS Transition Management Response frame was received. |

|DialogToken |Integer |1 – 255 |The Dialog Token to identify this BSS Transition |

| | | |Management transaction as received in the BSS Transition|

| | | |Management Response frame. |

|StatusCode |Integer |0 – 255 |As defined in 7.4.11.9. |

|PowerDownDelay |Integer |0 – 255 |As defined in 7.4.11.9 |

|TargetBSSID |MACAddress |Any valid individual|The BSSID of the BSS that the STA indicated to roam to |

| | |MAC Address |as received in the BSS Transition Management Response |

| | | |frame. |

10.3.52.7.3 When Generated

This primitive is generated by the MLME when transmission of the BSS Transition Management Request frame is acknowledged, (re) transmission of the BSS Transition Management Request frame fails, the BSS Transition Management Request frame contains invalid parameters, or for unspecified failure reasons.

10.3.52.7.4 Effect of Receipt

On receipt of this primitive the SME shall operate according to the procedure in 11.20.9.

11.20.9 BSS Transition Management for Network Load Balancing

11.20.9.1 BSS Transition Capability

The BSS Transition Management Query, BSS Transition Management Request, BSS Transition Management Response frames provide a means and a protocol to exchange the information needed to enable an AP to inform associated STAs that the AP is shutting down for a period of time; enable a network to manage BSS loads by influencing STA transition decisions and by initiating STA transition to selected target BSS(s).

This protocol enables the improved throughput, effective data rate and/or QoS for the aggregate of STAs in a network by shifting (via transition) individual STA traffic loads to more appropriate points of association within the ESS.

A STA that has a value of true for the MIB attribute dot11MgmtOptionBSSTransitionEnabled is defined as a STA that supports BSS Transition Management. A STA for which the MIB attribute dot11MgmtOptionBSSTransitionEnabled is true shall set the BSS Transition field of the Extended Capabilities element to 1.

The provisions in this clause for BSS Transition Management and network load balancing do not apply in an IBSS.

11.20.9.2 BSS Transition Management Query

A non-AP STA supporting BSS Transition Management may request a BSS Transition Candidate list by sending a BSS Transition Management Query frame to its associated AP if the associated AP indicates that it supports such capability in the Extended Capabilities information element.

Upon receipt of a BSS Transition Management Query frame from a non-AP STA, the AP shall respond with a BSS Transition Management Request Frame.

11.20.9.3 BSS Transition Management Request

An AP shall respond with a BSS Transition Management Request Frame in response to a BSS Transition Management Query frame, or aAn AP supporting BSS Transition Management may send an unsolicited BSS Transition Management Request frame to a non-AP STA at any time if the non-AP STA indicates that it supports such capability in the Extended Capabilities information element.

The AP shall include the BSS Transition Candidate List Entries field in the BSS Transition Management Request frame if the AP has information in response to the BSS Transition Management Query frame. The BSS Transition Candidate List Entries field contains one or more Neighbor Report elements describing the preferences for target AP candidates. A value of Preference “0” indicates that the AP being listed is an “excluded” AP, and STA shall not attempt to associate to the listed AP, unless the STA is unable to associate with any non-“excluded” APs that are compatible with the STA’s choice of SSID and, if the STA is associated with the AP that sent the Request, the STA has transmitted a BSS Transition Candidate Response frame to the associated AP with the reason of “reject”. The Preference values are used only to establish the relative order of entries within the given list at the given time, and for the given AP. The values between 1 and 255 provide the indication of order, with 1 indicating the most preferred AP within the given candidate list, increasing numbers representing decreasing preference relative only to entries with lower values of the Preference field, and equal numbers representing equal preference. The preference value is only valid before the Validity Interval has expired. Zero or more sub-elements may be included in the BSS Transition Candidate List Entries field. Load Sub-elements contain additional information describing the BSS load and QBSS Admission Control Capacity. The sub-element is used by a non-AP QoS STAs to select a QoS AP that is likely to accept future admission control requests, but it does not represent a guarantee that the HC shall admit these requests.

The Preferred Candidate List Included bit is set to “0” indicates that the receiving STA may ignore the Preferred Candidate List. The Preferred Candidate List Included bit set to “1” indicates that the sender expects the receiving STA to process this frame.

The AP sets the Power Down Included bit in the Request mode field to “1” to indicate that the BSS is shutting down or one or more BSS transition candidates are shutting downdown. The Power Down Included bit is set to “0” if no Power Down Duration information is included in the BSS Transition Management Request frame.

If the AP sets the Power Down Included (bit 3) field in the Request mode field to “1” the AP shall include the Power Down Duration fieldsub-element to indicate the expected time that it’s BSS will be shutdown for.

An AP may also include one Power Down Duration sub-element for each corresponding BSS that is shutting down in the BSS Transition Candidate List entry that represents the Power Down Duration value and a Power Down TSF value for the corresponding BSS. The power down duration may be different for different BSS. A Power Down Duration value of 0 indicates that the corresponding BSS will not be shutting down and may be a suitable candidate for the non-AP STA to transition to.

When a non-AP STA receives a BSS Transition Management Request frame with the Power Down Included bit set to 1 it shall send a BSS Transition Management Response frame with the Status code set to one of the following values:

• 0 – Accept

o If the non-AP STA accepts the AP is shutting down and does not want to delay or stop the AP from doing so

• 4 – Deny, Power Down Undesired

o If the non-AP STA does not want the AP to shutdown without any hint to when the AP may shutdown in the future

• 5 – Deny, Power Down Delay Requested

o If the non-AP STA requires the AP to delay the shutdown by the Power Down Delay field value as specified in the BSS Transition Management Response frame

The AP may choose to accept a response from a non-AP STA to terminate or delay the shutdown operation based on policies that are out of the scope of this standard.

Prior to the AP shutting down, the AP shall issue a Disassociation frame to each STA that transmitted a BSS Transition Management Response frame in response to a BSS Transition Management Request frame.

The AP sets the Abridged bit in the Request Mode field to “1” when it wishes to assign a preference value of “0” to all BSSIDs that do NOT appear in the BSSID list. The non-AP STA that receives the abridged bit with a value of “0” shall treat every considering BSSID as if it were present in the BSS Transition Candidate List with a Preference value of “0”. The AP sets the Abridged bit in the Request Mode field to “0” when the AP has no recommendation for or against any BSSID not present in the BSS Transition Candidate List Entries.

Disassociation Imminent bit in the Request Mode field set to “1” indicates that STA is to be disassociated from the current AP. The Disassociation Imminent field set to “0” indicates that disassociation from the AP is not imminent.

The Disassociation Timer indicates the time after which the AP will issue a Disassociation frame to this STA. A value of 0 indicates that the serving AP has not determined when it sends a Disassociation frame to this STA.

A STA receiving a MLME-BTM.indication containing BSS Transition Candidate List Entries may use this list of candidates, with their individual transition preference values, to make BSS transition decisions. Upon receiving a MLME-BTM.indication, the STA shall disregard any previous MLME-BTM.indication received from the same AP. The STA shall not use the corresponding BSS Transition Candidate List Entries information after the indicated Validity Interval. The STA may send a BSS Transition Management Query frame at any time to obtain an updated BSS Transition Candidate List Entries field.

A STA receiving a MLME-BTM.indication containing a Disassociation Timer value shall attempt to re-associate with some other AP before the indicated disassociation time. If the receiving STA cannot find a suitable AP with which to associate, the STA shall send a MLME-BTM.response containing a Status Code indicating “reject” before the indicated disassociation time.

11.20.9.4 BSS Transition Management Response

A STA receiving a MLME-BTM.indication may respond with a MLME-BTM.response.

A STA may include the result of its BSS transition decision in the Target BSSID field and Status Code field in the MLME-BTM.response. A Status Code set to "accept" indicates the STA will transition from the current BSS. The STA receiving a MLME-BTM.indication may reply with a MLME-BTM.response with a valid nonzero status code indicating rejection if it is unable to comply with this BSS Transition Management Request.

When a non-AP STA receives a BSS Transition Management Request frame with the Power Down Included field in the Request Mode field set to 1 it may send a BSS Transition Management Response frame with the Status code set to one of the following values:

• 0 – Accept

o If the non-AP STA accepts the AP is shutting down and does not want to delay or stop the AP from doing so

• 4 – Deny, Power Down Undesired

o If the non-AP STA does not want the AP to shutdown without any hint to when the AP may shutdown in the future

• 5 – Deny, Power Down Delay Requested

o If the non-AP STA requires the AP to delay the shutdown by the Power Down Delay field value as specified in the BSS Transition Management Response frame

The AP may choose to accept a response from a non-AP STA to terminate or delay the shutdown operation based on policies that are out of the scope of this standard.

Prior to the AP shutting down, the AP shall issue a Disassociation frame to each STA that the AP received a BSS Transition Management Response frame in response to a BSS Transition Management Request frame.

-----------------------

Abstract

This submission contains the normative text for the AP Power Notification proposal.

This proposal text is aligned with P802.11v-D3.00.

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