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Enhancing BSS Transition Management. Authors:. Date: 2008-11-07. Abstract. The current 802.11v D3.02 standard draft fails to regulate all technical aspects required by an effective network-initiated BSS transition process.
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Enhancing BSS Transition Management Authors: Date:2008-11-07 Kenan Xu, Nortel Networks
Abstract • The current 802.11v D3.02 standard draft fails to regulate all technical aspects required by an effective network-initiated BSS transition process. • Amendment proposals (on IEEE802.11v) are made to enable a streamlined network-initiated BSS transition process when the current AP cannot honor more resource requests, while neighboring APs have abundant unused radio resource. • The resulting network-initiated load shifting process is more effective and robust than an STA-initiated BSS transition process. Kenan Xu, Nortel Networks
Overview • BSS transition management in IEEE 802.11v. • Issues with BSS transition management process. • Proposed solutions to enhance the BSS transition process. • Standard amendment proposals. • Straw polls Kenan Xu, Nortel Networks
BSS Transition Management Procedures Assoc. AP STA 1.TSPEC rejection 2. Load balancing 3. Excessive frame loss 4. Excessive delay, etc. BSS Transition Query (Reason Code ) BSS Transition Request (Neighbor Report element) BSS Transition Response (status code, target BSSID) Kenan Xu, Nortel Networks
STA-initiated Load Shifting due to TSPEC Rejection STA Asso. AP ADDTS Request (TSPEC) 1. SUCCESS 2. INVALID_PARAMETERS 3. REJECTED_SUGGESTED_CHANGES (TSPEC) 4. REJECTED_FOR_DELAY_PERIOD 5. Tclas is not supported 6. Have no sufficient Tclas resource 2. No status code indicates the option of BSS transition. It is up to individual vendors to decide which status code to send and how to interpret the code. ADDTS Response (?status code) BSS Transition Query (TSPEC rejection) BSS Transition Request (Neighbor Report element) 1. AP is aware of the network resource better than STA. AP should inform the transition option and initiate the process. BSS Transition Response Kenan Xu, Nortel Networks
Network-initiated Load Shifting Solution One • A status code indicates explicitly BSS Transition option. • An unsolicited BSS Transition Request starts the BSS transition process. STA Asso. AP ADDTS Request (TSPEC) ADDTS Response (status = REJECTED_WITH_SUGGESTED_BSS_TRANS) BSS Transition Request (BSS Tran. Candidate List) BSS Transition Response Kenan Xu, Nortel Networks
Process Efficiency Issue • The neighbor report (candidate list) may be lost in the separate message. • Furthermore, a separate BSS Transition Management Request frame is not necessary. The neighbor report information can be conveyed by ADDTS response frame. Kenan Xu, Nortel Networks
Network-initiated Load Shifting Solution Two • A status code indicates BSS Transition option. • Neighbor report element piggybacked on ADDTS Response frame leads to a streamlined process of BSS transition. STA Asso. AP ADDTS Request (TSPEC) ADDTS Response (status, BSS Tran. Candidate List) Kenan Xu, Nortel Networks
ADDTS Response Frame 7 BSS Transition Can. List Entries Kenan Xu, Nortel Networks
Standard Amendment Proposal One • Add the new status code REJECTED_WITH_SUGGESTED_BSS_TRANSITION into the 11v standard draft, to be used by ADDTS Response frame. The non-AP STA receiving such a message should start BSS transition process upon receiving the upcoming BSS transition management request frame. • 7.3.1.9 Status Code field • 10.3.24.2 MLME-ADDTS.confirm • 10.3.24.4 MLME-ADDTS.response • 11.4.4 TS setup • 11.20.6 BSS Transition Management for Network Load Balancing Kenan Xu, Nortel Networks
Standard Amendment Proposal Two • Add the new status code REJECTED_WITH_SUGGESTED_BSS_TRANSITION into the 11v standard draft, to be used by ADDTS Response frame. • The network should add the neighbor report element to the ADDTS response frame if REJECTED_WITH_SUGGESTED_BSS_TRANSITION is present. The non-AP STA receiving such a message should start BSS transition process immediately. • 7.3.1.9 Status Code field • 7.4.2.2 ADDTS Response frame format • 10.3.24.2 MLME-ADDTS.confirm • 10.3.24.4 MLME-ADDTS.response • 11.4.4 TS setup • 11.20.6 BSS Transition Management for Network Load Balancing Kenan Xu, Nortel Networks
Summary • Proposals are made to streamline network-initiated BSS transition (load shifting) by coupling TS setup process with BSS transition process using a designated status code. • An STA becomes aware of all options when TSPEC is denied, and an appropriate behavior by the STA can be expected. • The network further expedites the BSS transition process by adopting BSS Transition Candidate List Entries in ADDTS response frame. • The solutions are simple (limited amendments) and effective (compared to STA-initiated process). Kenan Xu, Nortel Networks
References • IEEE Std. 802.11-2007 • IEEE 802.11v D3.02, September 2008 • 11-08-1295-00-000v-Enhancing-BSS-Transition-Management.doc, this is the corresponding .doc submission to accompany this presentation. Kenan Xu, Nortel Networks
Straw Poll Questions • Do you agree that there is a need to streamline the BSS transition process as described in this presentation?Yes: No: Abstain: • Do you agree that the second solution presented in this presentation should be included in the new revision of the 802.11v draft?Yes: No: Abstain: Kenan Xu, Nortel Networks
