WLAN Frame Collision Information in IEEE 802.11-14/1106r1
"Explore the severe problem of frame collisions in 11ax scenarios and how utilizing frame collision information can help reduce collisions, manage interference, and enhance network performance. Gain insights on the necessity of collision management in IEEE 802.11 WLAN environments. Examples of frame collisions and collision detection techniques are discussed for effective collision control."
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September 2014 doc.: IEEE 802.11-14/1106r1 WLAN Frame Collision Information Date: 2014-09-05 Authors: Name Peng Shao Affiliations Address NEC Communication Systems, Ltd. Phone +81-44-435-1177 email shao.pn@ncos.nec.co.jp 1753, Shimonumabe, Nakahara-ku, Kawasaki- shi, Kanagawa Japan 211- 8666 1753, Shimonumabe, Nakahara-ku, Kawasaki- shi, Kanagawa Japan 211- 8666 1753, Shimonumabe, Nakahara-ku, Kawasaki- shi, Kanagawa Japan 211- 8666 Yoshida Shimooji-cho 58- 13, Sakyo-ku, Kyoto Japan 606-8314 Yuki Baba NEC Communication Systems, Ltd. +81-44-435-1177 baba.yk@ncos.nec.co.jp Akira Matsumoto NEC Communication Systems, Ltd. +81-44-435-1177 matsumoto.kr@ncos.nec.c o.jp Peter Davis Telecognix Corporation +81-75-213-3599 davis@telecognix.com Submission Slide 1 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Abstract Frame Collision in 11ax scenarios is a severe problem, which is an obstacle to realizing the goals of 11ax. In this contribution, we propose that supporting the use of Frame Collision information will be useful for reducing collisions by management and control in 11ax. Submission Slide 2 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Background 1/2 Frame Collision is when two (or more) frame signals are transmitted or arrive at the same time Frame Collisions occur when CSMA/CA fails Failure of carrier-sensing ( hidden-terminal ) Failure of avoidance due to identical backoff times Frame Collisions cause performance degradation Interference, frame errors, retransmissions Frame Collisions occur often in 11ax scenarios with many terminals and high transmission rates [1][2] Necessity of collision management in 11ax has been mentioned in TGax [3][4] Submission Slide 3 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Background 2/2 Information related to Frame Collision is effective for reducing collisions by management and control Examples: Site Survey, Channel Selection, Association, Rate Control, Power Control, etc. Various forms of Frame Collision information can be obtained Examples: Transmitter side, Receiver side, separate sensor ( sniffer ) Frame Collision Detection (FCD) is needed to provide useful Frame Collision information Submission Slide 4 Peng Shao, NEC Communication Systems, Ltd.
September 2014 Examples of FCD: Power Signal Analysis doc.: IEEE 802.11-14/1106r1 (a) Power before and after frame Frame Collision Pattern Power Signal interference power power colliding frames time time frame (b) Power changes during frame power increase power fluctuation Submission Slide 5 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Examples of FCD: Power Signals 1. RSSI signal from power signal sensor [5] or spectral scan mode of WLAN card [6] No collisions Collision power power RSSI RSSI Frame-B Frame-A Frame-A Frame-A Frame-A + Frame-B time time 2. PHY state signal from WLAN card [7] tx_frame/2 rx_clear count Collision time Submission Slide 6 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Frame Collision (FC) Information Examples Existence or non-existence of collision events Statistics of collisions ex. number or percentage of collisions Collision TYPE information Store and share as Information Elements Use for management and control Submission Slide 7 Peng Shao, NEC Communication Systems, Ltd.
September 2014 Using FC information for Control 1/2 Example of Rate Control doc.: IEEE 802.11-14/1106r1 Incorrect rate control (unknown cause of loss): Decrease transmission rate Leads to increased probability of collision No ACK received Optimal rate control (loss cause known to be collision): No ACK received + collision detected transmission rate Leads to decreased probability of collision Increase Submission Slide 8 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Example of Collision Types : Frame B(interference) : Frame A Power Sa<Sb Sa=Sb Sa>Sb Pa Pb t Sa Ea Sb Eb Type II: Type I Type III transmitters of A and B choose same backoff transmitter of frame B cannot sense frame A transmitter of frame A cannot sense frame B Submission Slide 9 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Using FC information for Control 2/2 Examples of use of Collision Type Information Example of collision Collision type Examples of control by transmitter of frame A A Type I: transmitter of frame B cannot sense frame A Increase transmission power B Type II: transmitters of A and B choose same backoff Do nothing, or Increase CWmin A B Type III: transmitter of frame A cannot sense frame B A Decrease CCA level B : Frame A : Frame B(interference) Submission Slide 10 Peng Shao, NEC Communication Systems, Ltd.
September 2014 Examples of Collision Type Classification Method doc.: IEEE 802.11-14/1106r1 Use power time series information before, during and after frames Power Signal Frame Collision Pattern Colliding signal A Threshold B frame A Colliding signal A Threshold B frame A Submission Slide 11 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Summary and Next Steps Proposal of use of Frame Collision information for improving management and control in 11ax Examples of Frame Collision Detection using power signal analysis Examples of control using Frame Collision information For greater effect, information of collision types can be used Next: Propose method for handling FC information in 11ax Submission Slide 12 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Straw Poll Do you agree that TGax should support frame collision information? Yes No Abstain Submission Slide 13 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 References [1] MAC Efficiency Analysis for HEW SG , IEEE 802.11-13/0505r0, Minyoung Park (Intel) [2] Possible Approaches for HEW , IEEE 802.11-13/0758r0, Katsuo Yunoki (KDDI Labs) [3] Understanding Current Situation of Public Wi-Fi Usage - Possible Requirements for HEW - , IEEE 802.11-13/0523r2, Katsuo Yunoki (KDDI Labs) [4] Consideration on Efficiency Enhancement , IEEE 802.11-13/0854r1, SangHyun Chang (Samsung [5] IEICE Technical Report, SIP2012-125, p259-264, March 2014 , P. Shao [6] ath9k spectral scan , http://wireless.kernel.org/en/users/Drivers/ath9k/spectral_scan/ [7] Fwd: FW: Channel busy cycles , ath9k-devel ML, http://article.gmane.org/gmane.linux.drivers. ath9k.devel/9887/ Submission Slide 14 Peng Shao, NEC Communication Systems, Ltd.
September 2014 doc.: IEEE 802.11-14/1106r1 Backup: Example of rx_clear count power time Result of CCA time 0 2 4 4 4 4 2 0 rx_clear count time :0 :1 Submission Slide 15 Peng Shao, NEC Communication Systems, Ltd.
