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MCF Issues

MCF Issues. Date: 2009-05-30. Authors:. MCCA MCF EDCA. PSMP allows a STA to transmit frames from multiple ACs in a TXOP which can save more power. Why doesn’t MCCA allow a STA to transmit frames from multiple ACs in a MCCAOP to save more power?

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MCF Issues

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  1. MCF Issues Date: 2009-05-30 Authors: L. Chu et al

  2. MCCA MCF EDCA L. Chu et al

  3. PSMP allows a STA to transmit frames from multiple ACs in a TXOP which can save more power. Why doesn’t MCCA allow a STA to transmit frames from multiple ACs in a MCCAOP to save more power? The AP can start PSMP TXOP through EDCAF or PIFS without backoff. The EDCA TXOP definition is accordingly changed to: “Note that, as for an EDCA TXOP, a multiple frame transmission is granted to an EDCAF, not to a non-AP STA or AP, so that the multiple frame transmission is permitted only for the transmission of a frame of the same AC as the frame that was granted the EDCA TXOP, unless the EDCA TXOP obtained is used by an AP for a PSMP sequence, in which case, this AC transmission restriction does not apply to either the AP or the STAs participating in the PSMP sequence, but the specific restrictions on transmission during a PSMP sequence described in 9.16 (PSMP Operation) do apply”. In a reserved HCCA TXOP, it is up to the polled STA to decide which frames to transmit regardless the granted TXOP for a special TS. Why does MCCA have the restriction that the reserved MCCAOP shall only transmit the frames for the indicated AC? EDCA TXOP, PSMP & HCCA L. Chu et al

  4. In a MCCAOP, it is up to the MCCAOP owner to decide which frames to transmit regardless the granted AC. This is similar to HCCA reserved SP and PSMP reserved SP. This can further save the power when MCCA is used for power saving. Solutions: MCCAOP Access L. Chu et al

  5. If neighbor MPs have different DTIM beacon interval, A MP can not use the current MDAOP Advertisements element to forward its neighbor’s TX-RX time/interference time report without suffering collisions. This also makes selection of MDAOP TXOP complicated: A MP can not reference its Neighbor MP’s MDAOP TXOP as a fixed offset with respect to its own MDAOP TXOP, because the MDAOP TXOP “slide” with respect to each other. MP DTIM Beacon Interval Issue Duration Offset Service Interval Service Interval Service Interval TDIM Beacon Interval TDBTT TDIM Beacon Interval TDBTT TDIM Beacon Interval TDBTT TDBTT Duration Offset Service Interval Service Interval TDIM Beacon Interval TDIM Beacon Interval TDBTT TDBTT TDBTT L. Chu et al

  6. Solution 1: Each MCCA-enabled mesh STA must select the default DTIM beacon interval as its DTIM beacon interval. Each MCCA-enabled mesh STA should select its SI multiple of the default SI and multiple or sub-multiple of its neighbor SI. The SI should also be selected based on the traffic requirement (delay, throughput etc…). MP DTIM Beacon Interval Issue (Cont’d) DTIM Interval Offset MSTA1 Service Interval DTIM Interval Offset MSTA2 Service Interval L. Chu et al

  7. Solution 2: Each MCCA-enabled mesh STA must select the default DTIM beacon interval as its DTIM beacon interval. A mesh STA can not use MCCA if the default DTIM beacon interval is not used as its DTIM beacon interval. Each MCCA-enabled mesh STA should select its SI multiple of the default SI and multiple or sub-multiple of its neighbor SI. The SI should also be selected based on the traffic requirement (delay, throughput etc…). MP DTIM Beacon Interval Issue (Cont’d) DTIM Interval Offset MSTA1 Service Interval Service Interval DTIM Interval Offset MSTA2 Service Interval Service Interval L. Chu et al

  8. Solution 2: The initiator MP selects the DTIM beacon interval for the mesh network. When a MP joins a mesh network, it accepts the DTIM beacon interval broadcasted in the beacon/probe response frame. When a mesh network (say mesh network A) selects to merge with another mesh network (say mesh network B), mesh network A shall use mesh network B’s DTIM beacon interval. To maintain peer link relationship between MPs in mesh network A after the merging, mesh channel switch announcement element should include MP DTIM beacon interval of mesh network B. If two mesh networks have different DTIM beacon intervals, MPs in mesh network A shall tear down its MDAOP TXOPs. MP DTIM Beacon Interval Issue (Cont’d) L. Chu et al

  9. MCCA MCF EDCA L. Chu et al

  10. A TXOP owner may transmit a CF-End frame to truncate the NAV when it empties its transmission queue. An AP may respond by transmitting a CF-End frame after SIFS. A non-AP STA that is not the TXOP holder shall not transmit a CF-End frame. This is unfair to the neighbor mesh STAs of the TXOP receiver in a mesh BSS. A STA shall interpret the reception of a CF-End frame as a NAV reset. In a MBSS, if source mesh STA only transmits CF-End to truncate a TXOP, it is not fair to the neighboring mesh STAs of the destination STA. Solution: in subclause 9.9.1.7 add the following sentence “in a mesh BSS, a TXOP receiver may respond by transmitting a CF-End frame after SIFS. ” TXOP Truncation L. Chu et al

  11. Mesh STA is added to EDCA backoff procedure and Retransmission procedure. But a mesh STA has the same rules of the backoff and retransmission as a QoS STA. Since a mesh STA is a QoS STA, the mesh STA is not required to be mentioned in these places. Solution: delete subclause 9.9.15 and 9.9.1.6 from the draft. MCF EDCAF Backoff & Retransmission L. Chu et al

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