Transcript 11-16/0087
January 2016 doc.: IEEE 802.11-16/0087r1
NAV cancellation issues on MU protection
Date:
2016-01-19 Authors:
Name
Jinsoo Ahn
Affiliations Address
Yonsei Univ. Yonsei Univ. Woojin Ahn Ronny Yongho Kim Korea National University of Transportation
Phone email
c.kr
c.kr
Submission Slide 1 Jinsoo Ahn, Yonsei University
January 2016
Introduction
doc.: IEEE 802.11-16/0087r1
• •
TG specified Trigger frame variant MU RTS frame and Simultaneous CTS frame in SFD [1]
– The spec shall define a frame that solicits simultaneous CTS responses from multiple STAs to protect DL MU transmission – – MU RTS may request STAs to send non-HT CTS immediate response The MAC format of MU-RTS is a variant of trigger frame format
MU RTS frame and Trigger Frame would be interpreted as a normal data frame for legacy 11 devices to set a NAV by its duration field
Submission Slide 2 Jinsoo Ahn, Yonsei University
January 2016
M-RTS Simuta neous CTS
doc.: IEEE 802.11-16/0087r1
MU RTS/CTS procedure
STA 1 DL PPDU STA 2 DL PPDU STA 3 DL PPDU M-RTS Trigger Frame STA 1 BA STA 2 BA STA 3 BA Simuta neous CTS STA 1 UL PPDU STA 2 UL PPDU STA 3 UL PPDU M-BA • NAV NAV NAV NAV DL MU RTS/CTS procedure UL MU RTS/CTS procedure
DL MU and UL MU procedure is initiated by AP
– – – UL MU procedure is initiated by trigger frame of AP DL MU procedure is initiated by DL MU PPDU of AP DL and UL MU RTS/CTS procedure is also initiated by MU RTS frame of AP Submission Slide 3 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Recap : RTS NAV reset
• • •
RTS frame is sent by transmitter to set a NAV and to solicit CTS frame STAs which received RTS frame set a NAV if there are no detection of PHY-RXSTART.indication during (2 × aSIFSTime) + (CTS_Time) + aPHY-RX-START-Delay + (2 × aSlotTime) [2] If there are no response to the RTS frame, RTS NAV is reset due to the RTS timer
Submission Slide 4 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Idle NAV problem on MU RTS NAV
M-RTS No CTS • NAV
NAV for Nothing MU RTS NAV is set by Duration field of M-RTS
– Legacy STAs cannot recognize MU RTS, they recognize MU RTS as a Data Frame – – NAV from Data Frame cannot be reset itself RTS NAV reset would not be performed in MU RTS / Simultaneous CTS exchange even though there are no CTS response and Data transmission Submission Slide 5 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Idle NAV problem on Trigger Frame
Trigger Frame No UL response • NAV
NAV for Nothing MU RTS NAV is set by Duration field of Trigger Frame
– – TF - UL Data - BA(M-BA) is basic process of UL MU transmission Trigger Frame set long NAV for UL Data but transmission time of Trigger Frame is relatively short – – Hidden nodes cannot recognize absence of UL transmission Idle NAV problem would be happened if the trigger frame is failed Submission Slide 6 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Idle NAV problem
Non-NAV set STA NAV set STA Non-NAV set AP NAV set AP MU RTS MU RTS
•
Idle NAV problem could degrade channel usage and it might be worse in dense scenario
– OBSS cannot transmit its data due to its NAV duration even though there are no data transmission on original BSS – If there are many APs in original BSS area, more performance degradation might be observed due to
idle NAV
problem Submission Slide 7 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
• • M-RTS
Solution 1 : MU RTS reset
DL Frame prevents RTS NAV cancellation Trigger Frame prevents RTS NAV cancellation
STA 1 DL PPDU STA 2 DL PPDU M-RTS Trigger Frame STA 3 DL PPDU M-BA Simuta neous CTS STA 1 BA STA 2 BA STA 3 BA Simuta neous CTS STA 1 UL PPDU STA 2 UL PPDU STA 3 UL PPDU
RTS Timer Duration RTS Timer Duration
NAV NAV NAV NAV
Similar to conventional RTS reset, MU RTS reset could be adopted to solve MU RTS Idle NAV problem 11ax STAs which update its NAV setting based on MU RTS reset its NAV if no PHY-RXSTAT.indication primitive is detected from the PHY during MU RTS timer duration
Submission Slide 8 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Solution 1 : MU RTS reset
M-RTS
MU RTS Timer Duration
No DL PPDU(s) (Trigger, DL DATA, … ) No CTS • Actual NAV Original NAV (Legacy NAV)
MU RTS reset mechanism cannot solve the M-RTS NAV problem of conventional STAs
– – Conventional STAs cannot recognize M-RTS Fairness problem between 11ax STAs and legacy STAs Submission Slide 9 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Solution 2 : CF-END procedure for NAV reset
Trigger Timer+CF-END Duration
M-RTS
Trigger Timer
CF-END No CTS • •
NAV Cancellation for MU RTS
Actual NAV Original NAV
CF-END frame could reset NAV of receiver STAs If AP cannot receive simultaneous CTS so that AP would not transmit its DL MU PPDU or Trigger Frame after transmit MU RTS Frame, AP transmits CF-END frame after trigger timer to reset MU RTS NAV
Submission Slide 10 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Solution 2 : CF-END procedure for NAV reset
Trigger Timer+CF-END Duration
Trigger Frame
Trigger Timer
CF-END No UL Data
NAV Cancellation for TF
Original NAV Actual NAV •
Idle NAV problem on Trigger type frames could be solved by CF-END procedure for NAV reset
•
CF-END procedure with trigger timer could be applied on other trigger type frame not only MU RTS to reset NAV
Submission Slide 11 Jinsoo Ahn, Yonsei University
January 2016 doc.: IEEE 802.11-16/0087r1
Conclusion
• • • •
MU RTS could cause Idle NAV problem Idle NAV problem is also occurred in Trigger based UL transmission Using MU RTS reset timer (Solution 1) is a basic solution with no cost To solve Idle NAV problem on legacy STAs and Trigger Frame case, CF-END Procedure for NAV reset (Solution 2) also needs to be considered as a 11ax feature
Submission Slide 12 Jinsoo Ahn, Yonsei University
January 2016
StrawPoll 1
doc.: IEEE 802.11-16/0087r1
•
Do you agree to add to the TG Specification Frame work document?
– Spec shall use the legacy RTS reset timer to reset the NAV set by MU RTS frame. After receiving MU RTS, if a STA can not detect any signal during the RTS reset timer duration, the STA shall reset the NAV set by MU RTS frame at the expiry of the RTS timer.
• • • Y N A Submission Slide 13 Jinsoo Ahn, Yonsei University
January 2016
StrawPoll 2
doc.: IEEE 802.11-16/0087r1
•
Do you agree to add to the TG Specification Frame work document?
– AP may transmit CF-END frame after trigger timer (TBD) expires following MU RTS Frame if AP cannot detect the (Simultaneous) CTS frame(s). – CF-END frame may be transmitted after trigger timer (TBD) expires following Trigger Frame if AP cannot detect the UL response(s).
• Y • • N A Submission Slide 14 Jinsoo Ahn, Yonsei University
January 2016
References
doc.: IEEE 802.11-16/0087r1 [1] 15/0132r9 “Spec Framework” [2] IEEE Std 802.11-2012
Submission Slide 15 Jinsoo Ahn, Yonsei University