July 2015
doc.: IEEE 802.11-15/0880r2
Scheduled Trigger frames
Date: 2015-07-04
Authors:
Name
Affiliation
Address
Phone
Alfred Asterjadhi
[email protected]
5775 Morehouse Dr. San
Diego, CA, USA
Simone Merlin
Bin Tian
[email protected]
[email protected]
1700 Technology Drive San
Jose, CA 95110, USA
Carlos Aldana
George Cherian
[email protected]
[email protected]
5775 Morehouse Dr. San
Diego, CA, USA
Gwendolyn Barriac
[email protected]
Hemanth Sampath
[email protected]
Menzo Wentink
[email protected]
Richard Van Nee
Qualcomm
Straatweg 66-S Breukelen,
3621 BR Netherlands
Albert Van Zelst
Rolf De Vegt
Sameer Vermani
VK Jones
[email protected]
[email protected]
1700 Technology Drive San
Jose, CA 95110, USA
5775 Morehouse Dr. San
Diego, CA, USA
Tevfik Yucek
[email protected]
[email protected]
[email protected]
1700 Technology Drive San
Jose, CA 95110, USA
Youhan Kim
1
Submission
email
[email protected]
[email protected]
Slide 1
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Authors (continued):
Name
Affiliation
Address
Phone
19, Yangjae-daero 11gil,
Seocho-gu, Seoul 137-130,
Korea
Kiseon Ryu
[email protected]
Hyeyouong Choi
[email protected]
Jinyoung Chun
[email protected]
Jinsoo Choi
[email protected]
Jeongki Kim
Giwon Park
[email protected]
LG
Electronics
[email protected]
Dongguk Lim
[email protected]
Suhwook Kim
[email protected]
Eunsung Park
[email protected]
HanGyu Cho
[email protected]
Jinmin Kim
[email protected]
2200 Mission College Blvd,
Santa Clara, CA 95054
Shahrnaz Azizi
[email protected]
Eldad Perahia
[email protected]
2111 NE 25th Ave, Hillsboro
OR 97124, USA
Robert Stacey
Po-Kai Huang
Qinghua Li
Submission 1
email
+1-503-724-893
[email protected]
[email protected]
Intel
[email protected]
Xiaogang Chen
[email protected]
Chittabrata Ghosh
[email protected]
Rongzhen Yang
[email protected]
Laurent cariou
[email protected]
Slide 2
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Authors (continued)
Name
Affiliation
Address
Phone
email
Ron Porat
[email protected]
Matthew Fischer
[email protected]
Sriram
Venkateswaran
Broadcom
Tu Nguyen
Vinko Erceg
5488 Marvell Lane,
Santa Clara, CA, 95054
Lei Wang
858-205-7286
[email protected]
Hongyuan
Zhang
[email protected]
Yakun Sun
[email protected]
Liwen Chu
[email protected]
Jinjing Jiang
[email protected]
Yan Zhang
Marvell
[email protected]
Rui Cao
[email protected]
Sudhir Srinivasa
[email protected]
Saga Tamhane
[email protected]
Mao Yu
[email protected]
Edward Au
[email protected]
Hui-Ling Lu
[email protected]
1
Submission
Slide 3
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Authors (continued)
Name
Affiliation
Address
Phone
email
st
1
No. 1 Dusing 1 Road,
Hsinchu, Taiwan
James Yee
+886-3-567-0766
Alan Jauh
[email protected]
[email protected]
Mediatek
1
Chingwa Hu
[email protected]
Frank Hsu
[email protected]
2860 Junction Ave, San Jose,
CA 95134, USA
` Thomas Pare
+1-408-526-1899
[email protected]
m
ChaoChun Wang
James Wang
Jianhan Liu
1
[email protected]
[email protected]
Mediatek
USA
[email protected]
Tianyu Wu
[email protected]
Russell Huang
[email protected]
`
Submission
Slide 4
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Authors (continued)
Name
Affiliation
Phillip Barber
Address
Phone
pbarber@broadbandmobilete
ch.com
The Lone Star State, TX
Peter Loc
[email protected]
Le Liu
F1-17, Huawei Base, Bantian,
Shenzhen
Jun Luo
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
Yi Luo
F1-17, Huawei Base, Bantian,
Shenzhen
Yingpei Lin
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
Jiyong Pang
Zhigang Rong
Rob Sun
David X. Yang
Yunsong Yang
Zhou Lan
email
Huawei
+86-18601656691
[email protected]
+86-18665891036
Junghoon Suh
303 Terry Fox, Suite 400
Kanata, Ottawa, Canada
Jiayin Zhang
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
[email protected]
[email protected]
5B-N8, No.2222 Xinjinqiao
Road, Pudong, Shanghai
10180 Telesis Court, Suite
365, San Diego, CA 92121
NA
303 Terry Fox, Suite 400
Kanata, Ottawa, Canada
F1-17, Huawei Base, Bantian,
Shenzhen
10180 Telesis Court, Suite
365, San Diego, CA 92121
NA
F1-17, Huawei Base, Bantian,
SHenzhen
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
+86-18565826350
[email protected]
[email protected]
+86-18601656691
[email protected]
1
Submission
Slide 5
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Authors (continued)
Name
Thomas Derham
1
Affiliation
Address
Phone
Orange
[email protected]
1-1 Hikari-no-oka, Yokosuka,
Kanagawa 239-0847 Japan
Yasushi Takatori
[email protected]
Yasuhiko Inoue
Yusuke Asai
email
[email protected]
NTT
[email protected]
Koichi Ishihara
[email protected]
Akira Kishida
[email protected]
Akira Yamada
Fujio Watanabe
NTT
DOCOMO
3-6, Hikarinooka, Yokosukashi, Kanagawa, 239-8536,
Japan
[email protected]
m
3240 Hillview Ave, Palo
Alto, CA 94304
watanabe@docomoinnovatio
ns.com
Haralabos
Papadopoulos
hpapadopoulos@docomoinno
vations.com
Fei Tong
Innovation Park,
Cambridge CB4 0DS (U.K.)
+44 1223 434633
[email protected]
Hyunjeong Kang
Maetan 3-dong; Yongtong-Gu
Suwon; South Korea
+82-31-279-9028
[email protected]
m
Kaushik Josiam
1301, E. Lookout Dr,
Richardson TX 75070
(972) 761 7437
[email protected]
Mark Rison
Innovation Park,
Cambridge CB4 0DS (U.K.)
+44 1223 434600
[email protected]
Rakesh Taori
1301, E. Lookout Dr,
Richardson TX 75070
(972) 761 7470
[email protected]
Sanghyun Chang
Maetan 3-dong; Yongtong-Gu
Suwon; South Korea
+82-10-88641751
[email protected]
1
Samsung
1
Submission
Slide 6
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Authors (continued)
Name
Affiliation
Address
Phone
#9 Wuxingduan, Xifeng Rd
Xian, China
Bo Sun
[email protected]
Kaiying Lv
Yonggang Fang
email
[email protected]
ZTE
Ke Yao
Weimin Xing
Brian Hart
Pooya Monajemi
Cisco
Systems
170 W Tasman Dr, San Jose,
CA 95134
[email protected]
Joonsuk Kim
[email protected]
Aon Mujtaba
Guoqing Li
[email protected]
[email protected]
Apple
[email protected]
Eric Wong
[email protected]
Chris Hartman
[email protected]
1
Submission
Slide 7
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Introduction
•
MU procedures are under discussion in 11ax
– The AP enables multiple STAs to transmit UL frames via Trigger frames (TFs)
– MU STAs wait for the TF prior to transmitting UL frames
• Upon reception of a TF intended to them they can transmit to the AP
•
In this presentation we focus on trigger frame scheduling with TWT signaling [1]
– This way we also enable other useful operation modes for power save that fit in the
11ax use cases
• I.e., STAs wake up only in the allocated TWT SP and can sleep outside of them
•
For simplicity, we focus on the implicit TWT operation which enables:
– “Broadcast” TWT: Scheduled by the AP, irrespective of TWT requests, and indicated
in the Beacon for multiple STAs (a generic scheduling mechanism that covers
operation in [1])
– “Solicited” TWT: Scheduled by the AP, accounting for the STA’s TWT request
Submission
Slide 8
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Basics of Trigger TWTs
•
“Broadcast” trigger TWT:
–
AP indicates the target trigger times in a TWT response included in the Beacon
•
The pattern can be periodic, aperiodic (i.e., single indication for multiple Trigger frames)
–
•
The pattern is only valid for the Beacon Interval following the Beacon.
The AP can indicate the broadcast trigger TWTs during a TWT Setup
Next TWT
B
e
a
c
o
n
TWT Wake Interval
T
F
DL/UL
MU
T
F
DL/UL
MU
T
F
DL/UL
MU
T
F
DL/UL
MU
B
e
a
c
o
n
TWT element: Implicit TWT, Next TWT, TWT Wake Interval
•
“Solicited” trigger TWT:
–
A STA requests the AP to schedule TFs (using TWT request)
•
TWT pattern is based on STA’s UL traffic pattern and QoS requirements
–
–
The AP responds confirming or providing alternative TWT schedules
•
The AP allocates its resources based on multiple STA’s information
–
Submission
The pattern can be periodic or aperiodic
STAs with similar traffic pattern can be allocated in similar TWTs, with similar TWT service periods (SPs),
and other similar parameters
Slide 9
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Solicited Trigger TWT
TWT Setup(s)
Next TWT(s)
STA 1
STA 2
STA 4
Tri
gg
er
Poll 1
Poll 2
Poll 4
A
c
k
Tri
gg
er
BU 1
BU 2
BU 4
BA 1
BA 2
BA 4
TWT Wake
Interval
TWT SP
•
Trigger TWT setup (negotiated):
–
Setup of TWT parameters is the same as for basic TWT operation with the following additions:
•
•
•
Trigger TWT operation:
–
–
AP schedules a TF at the beginning of each TWT SP
Non-AP STAs wake up at the TWT, wait for the TF and get ready for MU DL/UL exchange
•
•
•
The HE non-AP STA may request scheduling of a TF at the start of each TWT
The AP confirms scheduling of a TF at the start of each TWT
STAs are not supposed to contend during the TWT SP but rather wait for the TFs sent by the AP
During the TWT SP, STAs can exchange PS-Polls, APSD trigger frames, UL/DL BUs, etc. upon
reception of TFs.
STAs that negotiate TWT need not wake up to read the Beacon frame
–
–
Submission
DL BU availability is notified during the TWT SP itself.
STAs can renegotiate their TWTs when a traffic pattern changes
Slide 10
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Broadcast Trigger TWT
(Target TBTT,
Listen Interval)
STA1, STA2
STA1, STA2
TIM
Beac
on
TWT
Res
Target trans.
Time 1
TF
SIFS
DL MU
Data
▪ ▪ ▪
TIM
Beac
on
▪ ▪ ▪
TIM
Beac
on
AP
Awake
State
TWT
Req
STA1,
STA2
SIFS
Doze
Doze
Target TBTT
•
UL
MU
PSPoll
▪ ▪ ▪
▪ ▪ ▪
Doze
Doze
Listen Interval
TWT setup for broadcast trigger TWT
–
–
TWT request/response can be exchanged by a STA and an AP to negotiate the target Beacon
frame monitored by the PS STA.
Example of operation
•
•
•
•
•
–
Submission
A STA sends a TWT Request to request the broadcast trigger TWT operation.
An AP sends a TWT Response including the Target Wake Time set to the target TBTT and TWT Wake
Interval set to the ListenInterval of the STA.
A STA monitors the Beacon frame with the period of TWT Wake Interval (ListenInterval) from the time
of Target Wake Time (target TBTT).
If a STA receives the target trigger times in a TWT response included in the Beacon, the STA may save
its power till the time and the STA wakes up at the target trigger time to receive the Trigger frame.
Otherwise, the STA save its power according to TWT Wake Interval.
Note. It is applicable to PS STAs which should monitor the TIM Beacon frame with certain
periodicity.
Slide 11
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Benefits of TWTs
•
TWT scheduling improves power saving for the SU case as exemplified in [1]
– It also eases contention as the STAs should not access the medium outside the
TWT SPs
•
For the MU case, the STA indicates/negotiates with the AP:
– The TWT SPs during which it is active and the rest of the times during which it is
inactive
• Similar benefits to the SU case: STAs save power, eases channel contention,
– To send TFs at the start of the TWT SPs
• Enables MU operation during the TWT SP and protects the medium access for the STA
–
–
•
Increases throughput as transmissions are protected at the receiver
Increases network efficiency due to MU transmissions and reducing collisions
The AP uses the TWT scheduling to:
– Spread out the wake up and access times of the STAs easing contention
– Allocate MU resources more efficiently (as it can be based on received feedback)
• Avoids allocating resources to STAs with no UL data
Submission
Slide 12
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
TWT element
Element
ID
Length
Control
Request
Type
Target
Wake
Time
TWT
Group
Assignment
Nominal
Minimum
Wake Duration
TWT Wake
Interval
Mantissa
TWT
Channel
NDP
Paging
(optional)
1
1
1
2
8 or 0
9 or 3 or 0
1
2
1
0 or 4
Octets:
B0
Bits:
•
B3
B4
B5
B6
B7
B9
B10 B14
B15
TWT
Request
TWT Setup
Command
Reserved
Triggered
Implicit
Flow Type
TWT Flow
Identifier
Wake Interval
Exponent
TWT Protection
1
3
1
1
1
3
5
1
Define a Triggered subfield in the Request Type field of the TWT element:
–
–
•
B1
Set to 1 in a TWT Request to request for a TF at the start of the TWT
Set to 1 in a TWT Response to indicate that a TF will be scheduled at the start of the TWT
Most of the use cases for 11ax seem to be covered by implicit TWT setup
–
So suggestion is that for 11ax the Implicit field of the TWT element be set to 1
•
Some more evaluations are needed to understand the benefits of explicit TWT
–
–
Submission
Which requires the use of TACK/STACK/BAT frames
Hence, here we focus only on the implicit TWT
Slide 13
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Summary of Trigger TWT
• Define implicit TWT operation for 11ax that enables:
– Solicited TWT:
• STA and the AP negotiate the TWT parameters
– STA sends TWT request and AP responds with a TWT response
– Broadcast TWT:
• AP indicates to STAs the TWT parameters
– AP sends TWT response to the STAs without receiving TWT requests
• The proposed Trigger TWT procedure
– Inherits the power saving properties of the TWT protocol [1]
Submission
Slide 14
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Straw Poll #1
•
Do you support to add the following text in the SFD:
– The spec shall include a mechanism that allows a target transmission time for a Trigger
frame to be indicated. The mechanism is based on implicit TWT operation and
additionally enables:
• Broadcast triggered TWT by including a TWT element in the Beacon
• Solicited triggered TWT by using implicit TWT negotiation procedure
•
•
•
Yes
No
Abstain
Submission
Slide 15
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
Straw Poll #2
• Do you support to add the following text in the SFD:
– When the broadcast triggered TWT is enabled, STA and AP may
exchange TWT request/response to indicate the target Beacon frame to be
monitored by the PS STA.
•
•
•
Yes
No
Abstain
Submission
Slide 16
A. Asterjadhi, H. Choi, et. al.
July 2015
doc.: IEEE 802.11-15/0880r2
References
[1] M. Fischer (Broadcom) et. al., 11-12-0823-00-00ah-targetwaketime
Submission
Slide 17