Proposed Resolution to CID 147 in CC12

1. Proposed Resolution to CID 147 in CC12 Date: 2014-9-8 Presenter: Dejian Li

2. Author List Dejian Li

3. Abstract • This is a submission of resolution to comment #147 in CC12. This submission provides an improved SP Protected Period mechanism for 11aj. Dejian Li

4. Background: Protected Period establishment • The intent of DMG Protected Period is to minimize the interference to/from the neighboring or local BSS. • It can limit the transmission during the DMG Protected Period to not more than one pair of a set of potentially interfering pairs of STAs. • Protected Period establishment for an SP • The source and destination STAs moves to and stays in Listening Mode during time interval (150us) that starts before the start of the SP. • A DMG Protected Period is established through an RTS/DMG CTS handshake. • Protected Period creation conditions in 11ad: • Enforced: Protected Period shall be created for every SP if the Protected Period Enforced field in the ECPAC policy element is equal to 1. • Un-enforced: except the above condition, whether to create a Protected Period is determined by the STAs. Dejian Li

5. Problems of the SP Protected period(1/2) • In 11ad, the STA lacks the schedule information of PCP/AP when determining whether creating Protected Period for its SP. • The scenarios that only the PCP/AP knows the schedule information includes: • Under the DBC mechanism, the PCPs/APs involved in a synchronization pair can receive the DMG Beacon frame from each other, thus understanding whether a 11ad STA’s SP of the neighboring BSS overlaps with an SP in its BSS. • A PCP/AP can receive the DMG Beacon frames from the other neighbor BSSs when clustering mechanism is used. • STAs may report the interference information to its PCP/AP using the TSCONST field and the interference report and cluster report mechanisms. • Only the PCP/AP may receive the DMG Beacon frames due to geographical locations. • In 11ad, if a destination STA received a RTS but has not been in Listening Mode for 150us, it shall not respond with a CTS. This leads to that the destination STA may not synchronize with the source STA. • In 11ad, the destination STA should transition to Listening Mode at least 150us before the start of an SP. • The Protected Period mechanism in 11ad is designed for single channel. Dejian Li

6. Problems of the SP Protected period(2/2) • Analysis for the above problems: • The cost for creating a Protected Period is very small • Because the Listening Mode is occurred before the start of the SP, there is little time loss for creating a Protected Period. • The cost for channel monitoring of the destination STA is hard to avoid. • Since 11ad has already specified that the destination STA should monitor the channel for at least 150us before the start of the SP according to 11ad. • The source and destination STAs can mitigate interference using the Protected Period mechanism with very low cost, but they lacks the information that whether the SP is overlapping with other SPs/CBAPs and the information that on which channel the overlapping occurs. Dejian Li

7. Resolution to SP Protected Period for 11aj • For a source STA, the assessment of whether an SP is a Protected Period should be done based on not only the directly received scheduling or interference information, but also the indication of the PCP/AP. • If the PCP/AP discovers the SP is overlapping with other SP/CBAP, it should indicate that Protected Period is forced to established; • Otherwise, the STA is allowed to determine whether to create Protected Period. • If the PCP/AP intends to allocate an overlapped SP under SPSH mechanism, it should not indicate an enforced SP protection. • If a 1.08GHz PCP/AP discovers that the potential interference comes from the 2.16GHz channel, extended channel protection should be performed by STAs. Dejian Li

8. Resolution of the SP dynamic truncation • Add Protected Period field using 2 reserved bit (B13, B14) in Allocation Control field to indicate whether the SP is enforced to be protected. • If the Protected Period field set to 0, the SP does not have to be a Protected Period; otherwise, the source and destination STA shall establish a Protected Period for this SP. • If the SP time overlapping occurs on the current operating channel, the Protected Period field is set to 1; • If the BSS is operating on a 1.08 GHz channel and the overlapped SP or CBAP is allocated on the 2.16GHz common channel, the Protected Period field is set to 2; • If the BSS is operating on a 2.16 GHz channel and the overlapped SP or CBAP is allocated on a 1.08GHz channel 5 or 7, the Protected Period field is set to 2; If the BSS is operating on a 2.16 GHz channel and the overlapped SP or CBAP is allocated on a 1.08GHz channel 6 or 8, the Protected Period field is set to 3; • For a CBAP allocation, the Protected Period field is reserved. Allocation Control field in the Extended Schedule element Dejian Li

9. Benefits of the Improved SP Truncation • The PCP/AP can indicate the source and destination STAs when Protected Period is forced to be established using its schedule and interference information, in order to • Provide more sufficient protection for SPs with low cost, • Give a definite channel scope which needs to be protected • The channel monitoring and the channel measurement procedure can be merged in order to save time using the proposed Protected Period field and the Measure Request element. Dejian Li

10. Summary • This submission provides solution for comment #147 on the comment resolution for CC12. • The Protected Period Enforced is indicated assistly by PCP/AP by adding Protected Period field in Allocation Control field. • The modifications made to 11ad: • Add a “Protected Period” field in the Extended Schedule element using 2 reserved bits • By using the proposed Protected Period field and the Measure Request element, the channel measurement and the channel monitoring can be merged. Dejian Li

11. Reference • In the IEEE P802.11ad-2012 Standard “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications – Amendment 3: Enhancements for Very High Throughput in the 60 GHz band,” December 2012. Dejian Li