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FST Issues (Comment 3026)

FST Issues (Comment 3026). Date: 2011-06-07. Authors:. Comment 3026. 4-stage protocol has the following issues: 1), it is not suitable for TDLS, IBSS transition since the new band operation is not be defined.

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FST Issues (Comment 3026)

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  1. FST Issues (Comment 3026) Date: 2011-06-07 Authors: L. Chu et al

  2. Comment 3026 • 4-stage protocol has the following issues: • 1), it is not suitable for TDLS, IBSS transition since the new band operation is not be defined. • 2), traffic stream-based transmition make the protocol complicated since eah stream that is transited to the new band needs a counter and different streams will work in new band in different time. • 3), Multi-Bamd information acquirement in OBand BSS should be defined. • 4), if ,in the old band, two FST STAs can not communicate with each other without forwarding, FST Setup frames should be encapsulated in data frame or defined as public action frame.

  3. 11ad D2.0: FST Summary • Two-stage FST (fast session transition) switch: FST Setup Request/Response are transmitted in old band/channel, FST ACK Request/Response are transmitted in new channel. • A multi-band STA shall include, in any FST Setup Request and Response, the capabilities, Supported/Extended Supported Rates, and Supported Channels elements that are applicable to the band and channel number indicated within its most recently transmitted Multi-band element. • In non-transparent multi-band Robust Security Network Association (RSNA), two STAs use the same Pairwise Master Key Security Association (PMKSA) for both the supported band and the current operating band, and create different Pairwise Transient Key Security Associations (PTKSAs) for different bands. In transparent multi-band RSNA, two STAs that establish a transparent multi-band RSNA create one PMKSA and one PTKSA for both the current operating band and other supported band(s). Station-based or stream-based transition Station-based transition Station-based or stream-based transition

  4. 11ad D2.0: New Band Operation • Two-stage FST switch: FST Setup Request/Response are transmitted in old band/channel, FST ACK Request/Response are transmitted in new channel. • If after FST Seup Request or/and Response exchange are successful, and the FST Responder decides to send Association Request to FST Initiator in new band (Oband), the FST Responder does not know which 20MHz channel (primary channel) should be used. • Because the primary channel of HT/VHT Operation is not known after FST Setup Request/Response are used. • Once FST Initiator and Responder are in Transition Done state, they can transmit data frame/FST Ack Request/Response frames in new band e.g. when IBSS is used in the new band. • But the HT/VHT Operation element, EDCA Parameter element are not known after FST Setup Request/Response are used.

  5. Proposed New Band Operation Negotiation • The new band operation shall be defined in FST setup Request. • FST initiator shall include EDCA Parameter element in FST Setup Request if 11e is used in the new OBand band. • FST initiator shall include EDCA Parameter element, HT Operation element in FST Setup Request if HT transmission is used in the new OBand band. • FST initiator shall include EDCA Parameter element, HT Operation element, VHT Operation element in FST Setup Request if VHT transmission is used in the new OBand band. • The FST responder may not support the proposed operation since the FST initiator may still not know Capability element etc. of the FST responder in the new band. • The FST responder sends FST Setup Response with Status Code = 37 and with the capabilities, Supported/Extended Supported Rates, and Supported Channels elements that are applicable to the new band and channel number. • The FST initiator can send the FST Setup Request again with the new parameters.

  6. 11ad D2.0: Multi-band Capability Acquirement • In a DBand BSS/PBSS, a STA can know if the neighbor STA supports multi-band operation through Announce/Information Request/Information Response if PCP or AP supports DBand signaling. • If PCP/AP does not support DBand signaling, a STA can not get neighbor STA’s multi-band information. • In 2.4GHz/5GHz BSS, there is no Announce, Information Request/Response mechanism. • Probe Request/Response can not be used here without change, since only AP or non-AP STA in IBSS can reply Probe Response after receiving Probe Request in the current 802.11 specification.

  7. Proposed FST Info Acquire • Method 1: Enhanced Probe Request/Response • If Probe Request/Response are used to acquire FST information, Multi-band elements shall be included in Probe Request/Response. • The following rule should be added to Probe Request/Response Tx/Rx rules: • A Multi-band capable STA responds to probe requests with Multi-band element. • Method 2: Double Probe Requests • An Multi-band STA sends Probe Request with Multi-band elements. • After receiving the Probe Request with Multi-band elements, another Multi-band STA sends the second Probe Request with Multi-band elements. • Method 3: Enhanced Information Request/Response • An OBand STA (AP or non-AP STA) can transmit/receive Information Request/Response frame. • A DBand non-AP STA can transmit/receive Information Request/Response frame from another DBand non-AP STA.

  8. Proposed FST Info Acquire (Cont’d) • Method 4: FST Setup Request/Response • When a multi-band STA receives FST Setup Request, it will respond with FST Setup Response. • When the destination does not support multi-band operation, it will never send FST Setup Response. • This mixes Multi-band information acquirement with FST setup which is not good. • It seems either one of Method 1-3 is ok. Propose to use Method 1.

  9. FST with TDLS link in OBand • There is no PMKSA in old band. • If the current band does not have PMKSA between FST peer STAs, The current Multi-band RSNA can’t be used. • After TDLS link setup, TDLS peer STAs still do not know if peer STA support Multi-band operation. • If one of FST STA is AP/PCP in old band, two FST STAs already know if peer STA supports Multi-band operation through Beacon, Association frames. 5GHz AP 5GHz AP PCP 60GHz Link TDLS Link

  10. FST Capability/Security with TDLS Link in Oband • TDLS Discovery Request, TDLS Discovery Response, TDLS Setup Request, TDLS Setup Response include Multi-band elements. • This is like Multi-band elements in Beacon/Association frames. • Security: Pairwise transient key in supported bands is created by the following methods, • If at least one of TDLS peer STAs has different MAC address in different band, 11z key creating algorithm and the TDLS Peer Key Handshake protocol will be used to calculate different PTKSA in different band. • The only difference in calculate transient keys for different bands is that MAC addresses and cipher suite in key calculation are different (from Multi-band IE for new band, from Link Identifier and RSNIE for the current band). • If each TDLS peer STA has same MAC address in two bands and two TDLS STAs use the same pairwise cipher suite in two bands, TDLS PTKSA will be used for another band. 5GHz AP 5GHz AP PCP 60GHz Link TDLS Link

  11. FST with Oband AP forwarding in old Band • FST Setup management frames and other FST related action frames can not be forwarded by AP since management frame forwarding by AP is not available in IEEE 802.11. 5GHz AP 5GHz AP PCP1 PCP2 PCP1 PCP2 60GHz Link Non TDLS capable in 5GHz

  12. Oband AP forwarding in old Band (Cont’d) • Solution: FST Setup management frames and other FST related action frames are encapsulated as data frames and be forwarded by AP transparently. • Use Ethertype 89-0d (Annex H of Revmb D8.0) to encapsulate FST related management frames. AP 1:FST Setup Request 2: FST Setup Response STA2 STA1 FST Setup Request/Response

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