Enhancing BSS Transition Management May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Enhancing BSS Transition Management Date: 2009-05-11 Authors: Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Abstract Amendment proposals (on IEEE802.11v) are made to enable a streamlined network-initiated BSS transition process indication when the current AP cannot honor more resource (TSPEC) requests, while neighboring APs have abundant unused radio resource. The resulting network-initiated load shifting indication process is more effective, efficient and deterministic in enabling an STA-initiated BSS transition process. Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Overview Issues with current BSS transition indication to an STA after TSPEC rejection Proposed solution to provide BSS transition indication to STAs after TSPEC rejection Standard amendment proposal Straw polls Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

Consequence of STA operations after TSPEC rejection May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Consequence of STA operations after TSPEC rejection If the ADDTS Request is rejected, the mobile STA doesn't know its full range of possible next steps. Currently, the mobile STA can: retry with new TSPEC settings, transition to another AP based on its own logic, issue a BSS transition query to the current AP, reject the session, or Wait. Each of these alternatives involves a multistep sequence which could fail, require successive attempts or result in delays in obtaining the desired traffic service. Adding a status code to suggest load shifting would make a deterministic and efficient indication for the STA to start a BSS transition Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

STA-initiated operations due to TSPEC Rejection May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 STA-initiated operations due to TSPEC Rejection STA Associated AP ADDTS Request (TSPEC) There is no existing status code to indicate the opportunity of BSS transition. A status code to indicate the opportunity for BSS transition is critical to enable the STA with the best next step ADDTS Response (?status code) 1. SUCCESS 2. INVALID_PARAMETERS 3. REJECTED_SUGGESTED_CHANGES (TSPEC) 4. REJECTED_FOR_DELAY_PERIOD 5.REJECTED_WITH_SUGGESTED_BSS_TRANSITION (Proposed Status Code) STA possible actions after TSPEC rejection: Try new TSPEC settings Try another AP Request a BSS transition Reject Session Wait When the TS request is rejected, the handset doesn't know its full range of possible next steps. Currently it can retry with new Tspec settings, retry another AP based on its own logic, request a BSS transition, reject the session or wait. The option to choose BSS transition is missing Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

Standard Amendment Proposal May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Standard Amendment Proposal Add the new status code REJECTED_WITH_SUGGESTED_BSS_TRANSITION, to be optionally used by an AP within an ADDTS Response frame. If an AP rejects a TSPEC request and is aware of alternative candidate APs that can meet the request and the non-AP STA supports the BSS Transition capability, the AP can set the status code to REJECTED_WITH_SUGGESTED_BSS_TRANSITION . A non-AP STA receiving such a message immediately starts the BSS transition process. Affected clauses: 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 Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

802.11v BSS Transition Management Indication due to TSPEC rejection May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 802.11v BSS Transition Management Indication due to TSPEC rejection Current AP STA ADDTS Response ( STATUS CODE = REJECTED_WITH_SUGGESTED_BSS_TRANSITION ) Indicate to the STA the availability of resources within neighboring APs BSS Transition Query (Reason Code ) BSS Transition Request (Neighbor Report element) BSS Transition Response (status code, target BSSID) Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Proposal to add BSS transition indication status code with TSPEC response SUCCESS 38 INVALID_PARAMETERS The request has not been successful as one or more parameters have invalid values 39 REJECTED_WITH_SUGGESTED CHANGES The TS has not been created because the request cannot be honored; however, a suggested TSPEC is provided so that the initiating STA may attempt to set another TS with the suggested changes to the TSPEC 47 REJECTED_FOR_DELAY_PERIOD The TS has not been created; however, the HC may be capable of creating a TS, in response to a request, after the time indicated in the TS Delay element. New status code REJECTED_WITH_SUGGESTED_BSS_TRANSITION The TS has not been created because the request cannot be honoured; however, the HC suggests the STA to transition to other BSSs to setup the TS. Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Summary Proposal to streamline network-initiated BSS transition (load shifting) indication by coupling the TS setup process to the BSS transition process using a designated status code. A STA becomes aware of all opportunities when a TSPEC request is denied. The process to transition becomes more efficient and deterministic, should the STA decide to transition to another AP The solution requires only the addition of a status code, providing STA with valuable information. Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

References IEEE Std. 802.11-2007 IEEE 802.11v D4.01, January 2009 May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 References IEEE Std. 802.11-2007 IEEE 802.11v D4.01, January 2009 Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks

May 2009 doc.: IEEE 802.11-08/1294r2 May 2009 Straw Poll Questions Do you agree that a TSPEC response with a status code suggesting a BSS transition should be included in the new revision of the 802.11v draft? Yes: No: Abstain: Guyves Achtari, Nortel Networks Guyves Achtari, Nortel Networks