TDD-SP Coexistence Challenges in IEEE 802.11 Networks
Explore the challenges of Time-Division Duplex Spatial Reuse (TDD-SP) coexisting in IEEE 802.11 networks. Issues arise from TDD-SP devices accessing channels without sensing, impacting coexistence with other devices. Proposed solutions include announcing channel usage and actions for STAs detecting TDD-SP devices.
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Sep 2018 doc.: IEEE 802.11-18/1586r1 TDD-SP Coexistence Date: 2018-09-12 Name Affiliation Address Phone Email Mohamed Abouelseoud Sony 1730 N. First Street, San Jose CA 95112 +1-408-352-4027 Mohamed.Abouelseoud(at)so ny.com Kazuyuki Sakoda Sony 1730 N. First Street, San Jose CA 95112 +1-408-352-4405 kazuyuki.sakoda(at)sony.com Mohamed Abouelseoud, Sony Submission Slide 1
Sep 2018 doc.: IEEE 802.11-18/1586r1 Problem Statement Devices operating TDD SP can access the channel without sensing the channel TDD-SP is not enforcing listen before talk to access the channel for transmission There are concerns from 11ay members of TDD-SP Coexisting with SRDs and even other TDD-SP devices Other devices operating CBAP might struggle to access the channel and suffer from severe interference or even completely blocked if collocated with TDD-SP devices Mohamed Abouelseoud, Sony Submission Slide 2
Sep 2018 doc.: IEEE 802.11-18/1586r1 Proposed Approach TDD-SP devices should announce its existence and channel usage (time allocation and spatial allocation) so other devices can take actions Mohamed Abouelseoud, Sony Submission Slide 3
Sep 2018 Actions taken by STAs detecting TDD-SP devices (1) STAs might switch to another channel knowing that there is a TDD SP device STAs might try to access the same channel if the TDD- SP device is lightly scheduled STAs might try to access the same channel at time when the TDD-SP device TX/RX slots are unassigned doc.: IEEE 802.11-18/1586r1 Beacon interval scheduling and TX/RX directional announcement TDD-SP scheduled T R T T X BTI BTI TX TX RX RX RX X X X Unscheduled TDD-SP slots Mohamed Abouelseoud, Sony Submission Slide 4
Sep 2018 Actions taken by STAs detecting TDD-SP devices (2) doc.: IEEE 802.11-18/1586r1 STAs might access the channel if TDD-SP is lightly scheduled in its direction Occupied resources Victim STA 2 TDD SP Allocation BTI BTI TDD SP STA Beacon interval scheduling and TX/RX directional announcement Allocated resources for users Victim STA 1 Victim STA 3 Occupied resources Mohamed Abouelseoud, Sony Submission Slide 5
Sep 2018 Actions taken by STAs detecting TDD-SP devices (3) doc.: IEEE 802.11-18/1586r1 STAs might access the channel in a different direction that is not affected by the TDD-SP device Blocked direction Non- Blocked direction Victim STA 2 TDD SP STA Victim STA 1 Occupied resources Mohamed Abouelseoud, Sony Submission Slide 6
Sep 2018 doc.: IEEE 802.11-18/1586r1 Possible TDD-SP Announcement TDD-SP shall transmit a frame in the direction of the scheduled TDD-SP transmission Announce TDD-SP channel occupancy (Extended Schedule element) Announce TDD-SP Scheduling information ( TDD Slot Schedule and TDD Slot Structure elements) Announce TX beam direction used by TDD-SP devices for each TDD Slot Schedule element Mohamed Abouelseoud, Sony Submission Slide 7
Sep 2018 doc.: IEEE 802.11-18/1586r1 TDD-SP Coexistence Example TDD-SP STA3 Slot Sch TX Beam X Slot Sch TX Beam Y Extended Sch Slot Strc. TRNs Beacon -TX Beam X TDD-SP devices should send a beacon in each direction where there is a scheduled TDD-SP transmission The beacon should contain: Extended schedule element TDD Slot Structure element TDD Slot Schedule elements with TX Beam ID of the scheduled transmission TRN fields Dir. Y STA1 transmitting beacon with allocation and direction information in direction X TDD-SP STA1 Dir. X STA B TDD-SP STA2 Channel access attempt for STA A and STA B communication Beacon TX beam ID matched Allocation TX beam ID STA A TDD-SP STA3 Dir. Y TDD-SP STA1 STA 1 transmitting TRN fields Dir. X STA B Channel access attempt for STA A and STA B communication TDD-SP STA3 STA A RX antenna training Dir. Y TDD-SP STA1 Dir. X STA B Direction available for channel access STA A Busy channel direction Mohamed Abouelseoud, Sony Submission Slide 8
Sep 2018 doc.: IEEE 802.11-18/1586r1 TDD-SP Coexistence Example (2) TDD-SP STA3 Slot Sch TX Beam X Slot Sch TX Beam Y Extended Sch Slot Strc. TRNs Beacon -TX Beam X A STA trying to access the channel compares the beacon TX beam ID with the TX beam ID of TDD Slot Schedule elements, when matching: A TDD SP device is active STA can switch channel or try to access the channel if possible STA can decide based on the TDD-SP Slot Schedule element if and when to access the channel Dir. Y STA1 transmitting beacon with allocation and direction information in direction X TDD-SP STA1 Dir. X STA B TDD-SP STA2 Channel access attempt for STA A and STA B communication Beacon TX beam ID matched Allocation TX beam ID STA A TDD-SP STA3 Dir. Y TDD-SP STA1 STA 1 transmitting TRN fields Dir. X STA B Channel access attempt for STA A and STA B communication TDD-SP STA3 STA A RX antenna training Dir. Y TDD-SP STA1 Dir. X STA B Direction available for channel access STA A Busy channel direction Mohamed Abouelseoud, Sony Submission Slide 9
Sep 2018 doc.: IEEE 802.11-18/1586r1 TDD-SP Coexistence Example (3) TDD-SP STA3 Slot Sch TX Beam X Slot Sch TX Beam Y Extended Sch Slot Strc. TRNs Beacon -TX Beam X TDD-SP device sends TRN fields with the beacon for other STAs to determine direction of potential interference STA performs RX beam training to determine the RX beams affected by the TDD-SP device STA can access the channel in directions other those affected by the TDD-SP device Dir. Y STA1 transmitting beacon with allocation and direction information in direction X TDD-SP STA1 Dir. X STA B TDD-SP STA2 Channel access attempt for STA A and STA B communication Beacon TX beam ID matched Allocation TX beam ID STA A TDD-SP STA3 Dir. Y TDD-SP STA1 STA 1 transmitting TRN fields Dir. X STA B Channel access attempt for STA A and STA B communication TDD-SP STA3 STA A RX antenna training Dir. Y TDD-SP STA1 Dir. X STA B Direction available for channel access STA A Busy channel direction Mohamed Abouelseoud, Sony Submission Slide 10
Sep 2018 doc.: IEEE 802.11-18/1586r1 Straw Poll (1) Do you support the following approach for TDD-SP coexistence? A STA employing TDD-SP shall transmit periodic beacon frame in the direction of each scheduled TDD-SP transmission to announce TDD-SP channel occupancy, scheduling information and spatial directional information so other STAs can take actions Yes No Abstain Mohamed Abouelseoud, Sony Submission Slide 11
