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HCF in an IBSS

HCF in an IBSS. Toshihiro Fujita SONY Corporation. Background. Request for QoS in an IBSS. Outline. 1. Definition of a QIBSS 2. How to determine the QSTA as HC. Definition of a QIBSS. The IBSS with which the same QoS facility as QBSS is offered by QSTA which has HCF capability.

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HCF in an IBSS

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  1. HCF in an IBSS Toshihiro Fujita SONY Corporation Toshihiro Fujita, SONY

  2. Background Request for QoS in an IBSS Toshihiro Fujita, SONY

  3. Outline 1. Definition of a QIBSS 2. How to determine the QSTA as HC Toshihiro Fujita, SONY

  4. Definition of a QIBSS • The IBSS with which the same QoS facility as QBSS is offered by QSTA which has HCF capability. Toshihiro Fujita, SONY

  5. How to determine the QSTA as HC (1) - The HC in a QIBSS transmits beacon with QoS information. - The QSTA which is going to enter in a QIBSS searches for the beacon during predefined time. The time is defined as dot11QIBSSScanPeriod in the MIB. If the frame was detected, the QSTA transmits “Association” to HC in order to enter the QIBSS. Transmission of beacon with QoS information will be started, if the frame cannot be detected and the QSTA has HC capability. Toshihiro Fujita, SONY

  6. How to determine the QSTA as HC (2) • If some QSTA which has HC capability has not received beacon with QoS information during predefined time, these QSTAs try to send beacon with QoS information with random backoff. The time is defined as dot11QIBSSMissBeaconThreshold in the MIB. The QSTA that wins this arbitration becomes new HC. • If a HC receives a beacon with QoS information from other QSTA, the HC should stop transmission of beacon, except for the case that it is associated with a QSTA. [Case1] If a HC receives a beacon with QoS information from other QSTA, and both HCs are associated with a QSTA, the HC which receives the beacon a predefined number of times should stop transmission of its beacon. The number of frames is defined as dot11QIBSSContentionnumber in MIB.[Case2] Toshihiro Fujita, SONY

  7. Associate Beacon Interval Not HC Still HC Associate Beacon Interval Not HC HC(w QSTA) Other HC(w QSTA) Still HC [Case1] [Case1] Beacon w QoS Beacon w QoS HC(no QSTA) Other HC(w QSTA) Beacon w QoS Beacon w QoS Beacon w QoS Beacon w QoS [Case2] [Case2] Beaon w QoS Beacon w QoS Beacon w QoS Beacon w QoS Beacon w QoS Beacon w QoS Beacon w QoS Beacon w QoS Beaon w QoS Toshihiro Fujita, SONY

  8. Beacon generation in a QIBSS • Beacon is generated by HC in a QIBSS. • QSTAs in a QIBSS should not generate Beacon. Toshihiro Fujita, SONY

  9. Signaling QSTA1 QSTA2(HC) QSTA3(NEW) <---- Beacon with QoS information ----- Association Req -----> <---- Association Res ------- <-------------- Beacon with QoS Information -------------> <------ Association Req ----- (request to enter this QIBSS) ------ Association Res -----> <-------- AddTS Req --------- <-------- AddTS Req -------- --------- AddTS Res --------> ------------ CF Poll ----------> <-------------------------- QoS Data --------------------------- <----------------------- BurstACK Req ----------------------- -------------------------- Burst ACK -------------------------> <---------------- Beacon with QoS information -----------> Toshihiro Fujita, SONY

  10. bits:0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ESS IBSS CF- CF-poll Privacy Short PBCC Channel QoS FEC Bridge rsrv rsrv rsrv rsrv Extended Pollable request preamble agility Portal (0) (0) (0) (0) capability element 0 1 X X X X X X 1 X X 0 0 0 0 X Capability Information in Beacon with QoS information Toshihiro Fujita, SONY

  11. HC(QSTA1) STA1 Association Association QSTA3 STA3 QSTA2 STA2 IBSS/QIBSS • QSTA2 associates with QSTA1(HC) • QSTA3 associates with QSTA1(HC) Toshihiro Fujita, SONY

  12. HC(QSTA1) HC(QSTA4) HC(QSTA1) HC(QSTA4) QSTA3 QSTA6 QSTA3 QSTA6 QSTA2 QSTA5 QSTA2 QSTA5 A QSTA moves to another QIBSS • QSTA5 can’t rceive Beacon with QoSI from QSTA4(HC) or QSTA5 disassociates from QSTA4(HC) • QSTA5 scans and detects QSTA1(HC) • QSTA5 associates with QSTA1(HC) Toshihiro Fujita, SONY

  13. QSTA1 HC(QSTA4) HC(QSTA1) HC(QSTA4) QSTA3 QSTA6 QSTA3 QSTA6 QSTA2 QSTA2 QSTA5 QSTA5 Merge • QSTA1(HC) detects QSTA4(HC) and QSTA4(HC) detects QSTA1(HC) • QSTA1 stop transmission of Beacon • QSTA1 associates with QSTA4(HC) • QSTA2 scans and detects QSTA4(HC) • QSTA3 scans and detects QSTA4(HC) • QSTA2 associates with QSTA4(HC) • QSTA3 associates with QSTA4(HC) • QSTA1 requests Tspec to QSTA4(HC) Toshihiro Fujita, SONY

  14. QSTA1 HC(QSTA4) HC(QSTA4) HC(QSTA1) QSTA6 QSTA3 QSTA6 QSTA3 QSTA2 QSTA2 QSTA5 QSTA5 Split • QSTA1 can’t receive Beacon with QoSI from QSTA4(HC) or QSTA1 disassociates from QSTA4(HC) • QSTA3 can’t receive Beacon with QoSI from QSTA4(HC) or QSTA3 disassociates from QSTA4(HC) • QSTA1 scans • QSTA3 scans • QSTA1 transmits Beacon with QoSI • QSTA3 associates with QSTA1(HC) • QSTA1 requests Tspec Toshihiro Fujita, SONY

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