doc.: ieee 802.11-12/0831r0 submission july 2012 yongho seok, lg electronicsslide 1 uplink channel...

doc.: IEEE 802.11-12/0831r0

Submission

July 2012

Yongho Seok, LG ElectronicsSlide 1

Uplink Channel Access General Procedure

Date: 2012-07-12Authors:

Name Affiliations Address Phone Email

Yongho Seok LG ElectronicsLG R&D Complex

Anyang-Shi, Kyungki-Do, Korea

+82-31-450-1947 [email protected]

Minyoung Park Intel Hillsboro, OR +1 503 712 4705 [email protected] Yong Liu Marvell [email protected] Ghosh Nokia [email protected] Simone Merlin Qualcomm San Diego, CA +1 858 845 1243 [email protected] George Calcev Huawei Rolling Meadows, IL,

[email protected]

Matthew Fischer Broadcom [email protected] Eric Wong Broadcom Sunnyvale, CA +1 408 922 6672 [email protected] Jinsoo Choi LG ElectronicsJeongki Kim LG ElectronicsJin Sam Kwak LG ElectronicsSantosh Abraham QualcommMenzo Wentink QualcommAlfred Asterjadhi QualcommAmin Jafarian QualcommHemanth Sampath QualcommVK jones Qualcomm

doc.: IEEE 802.11-12/0831r0

Submission Slide 2

Name Affiliations Address Phone EmailAdrian Stephens IntelTom Tetzlaff IntelEmily Qi IntelHongyuan Zhang MarvellSudhir Srinivasa MarvellOsama Aboul Magd HuaweiYoung Hoon HuaweiBetty Zhao HuaweiDavid Yangxun Huawei

Bin Zhen Huawei

ChaoChun Wang MediaTekJames Wang MediaTekJianhan Liu MediaTekVish Ponnampalam MediaTekJames Yee MediaTekHuai-Rong Shao Samsung ElectronicsChiu Ngo Samsung ElectronicsMinho Cheong ETRIJae Seung Lee ETRIHyoungjin Kwon ETRIHeejung Yu ETRISok-kyu Lee ETRISun, Bo ZTELv, Kaiying ZTE

Authors:

July 2012

doc.: IEEE 802.11-12/0831r0

Submission Yongho Seok, LG ElectronicsSlide 3

Authors:Name Affiliations Address Phone Email

Sayantan Choudhury NokiaTaejoon Kim NokiaKlaus Doppler NokiaEsa Tuomaala NokiaKen Mori PanasonicRojan Chitrakar PanasonicHaiguang Wang I2RShoukang Zheng I2RYeow Wai Leong I2RZander Lei I2RJaya Shankar I2RAnh Tuan Hoang I2RJoseph Teo Chee Ming I2R

July 2012

doc.: IEEE 802.11-12/0831r0

Submission

July 2012


Introduction

• 11ah use case includes a large outdoor network – For an outdoor smart grid network, the number of STAs can be 2007+

– TIM element may cover few hundreds to few thousands STAs

– Bits set to one in the TIM element may trigger too many PS-Poll/trigger frame transmissions from the STAs within a short period of time

– Many stations at the edge of the coverage area could be hidden to each other for uplink transmissions

doc.: IEEE 802.11-12/0831r0

Submission

July 2012


TIM Triggered Hidden Node Problem

• Too many bits set in the TIM element may trigger too many PS-Poll/trigger frame transmissions right after the beacon frame within a short period of time– Increase collisions between the hidden nodes

STA1 STA2

APSTA2’s transmission rangeSTA1’s transmission range

TIM (n bits set to 1)

Beacon interval

STA1

STA2

STAn

…

PS-Poll/trigger frame

n transmissions within a short period of time

doc.: IEEE 802.11-12/0831r0


TIM Triggered Hidden Node Problem

• In order to solve TIM Triggered Hidden Node Problem

– One of solutions is either to spread out the uplink transmissions (PS-Poll/Data) over a long period of time or to delay the contention process for sending its PS-poll.

• Both solutions have a similarity about delaying or spreading the uplink transmission

• Alternative way is that PS-Poll and Data Transmission are separated to different time windows.

– Only STAs covered by the AID segment are allowed to access channel within a restricted access window (RAW)

DTIM-1

TIM-1.1

TIM-1.2

TIM-1.3RAW RAW RAW RAW

July 2012

doc.: IEEE 802.11-12/0831r0


TXOP Rule

Beacon Interval

A

P

D

Collision by Hidden Nodes

A

P * P: Poll, D: DATA, A: ACK

July 2012

doc.: IEEE 802.11-12/0831r0


Uplink Channel Access Protocol

Beacon Interval

Restricted Access Window (RAW)

Slot Boundary

Slot Boundary

Slot Boundary

Slot Boundary

Slot Boundary

Slot Boundary

Slot duration

July 2012

doc.: IEEE 802.11-12/0831r0


Uplink Channel Access Protocol

• RAWs with different slot durations

– If the TXOP rule is applied, a frame exchange sequence (an initial frame and a response frame) in a restricted access window shall be limited to a Slot Duration

– RAW1 can be a potentially protected poll interval.

– RAW2 can be a potentially data delivery interval.

Beacon Interval

RAW1

A P AP

* P: PS-Poll/Trigger frame D: DATA, A: ACKRAW2

AD AD

Slot duration = Ts1 Slot duration = Ts2 > Ts1

July 2012

doc.: IEEE 802.11-12/0831r0


Uplink Channel Access Example

• RAW1 (=Protected Poll Interval)– GrPS IE of RAW1 indicates that only the STAs that meet the below conditions can access RAW1

• The RAW is allowed only to the STA’s with AID bit = 1 in the TIM IE

• Slot duration = Ts1 ,where Ts1 is set to (PS-Poll + SIFS +ACK) or (Null Data + SIFS +ACK)

• TXOP cross slot boundary = not allowed

– This effectively makes RAW1 to be used for only PS-Poll or Null-Data trigger frames

• RAW2 (=Data Delivery Interval)– GrPS IE of RAW2 indicates that only the STAs that meet the below conditions can access RAW2

• The RAW is allowed only to the STA’s with AID bit = 1 in the TIM IE

• Slot duration = Ts2 ,where Ts2 is set to be large enough to transmit (Data + SIFS +ACK)

• TXOP cross slot boundary = not allowed

– This effectively makes RAW2 to be used for the AP to transmit Data frames to the STAs with their AID bits set to 1

– If there is time left in a time slot, a STA can transmit data to the AP as long as it doesn’t cross the slot boundary

Beacon Interval

RAW1

A

P

• P: Poll• D: Data (APSTA)• D: Data (STAAP)• A: ACK

RAW2

A

D

Slot duration = Ts1 Slot duration = Ts2 > Ts1

P P P

1 0 1 0 0 1 0 0 1 0

TIM bitmap (4 AID bits are set to 1)

D D DD

APSTAi

AP STAj

STAj AP

July 2012

doc.: IEEE 802.11-12/0831r0


• AP may indicate to a paged STA a channel access slot after which the STA is allowed to contend

– Preferred an implicit indication, based on TIM, so that the Beacon is not overloaded

– Additional information [TBD] for determining a RAW duration may be needed in (short) Beacon

• After receiving TIM, STA transmits the PS-Poll/Trigger frames to a AP not earlier than the slot boundary of its channel access slot based on EDCA

• AP may indicate to a paged STA, that it will be sending traffic to a STA not earlier than a given downlink BU delivery slot.

– Indication of the downlink BU delivery slot should not overload the beacon

• New management frame indicates the downlink BU delivery slot per each STA after all PS-Poll/Trigger frame transmission completed.

• AP may protect the PS-Poll/Trigger frames by setting the NAV– The paged STAs can ignore the NAV set by the AP. If NAV is set, then only paged STAs

can send PS-Poll/Trigger frames during the RAW

Downlink Buffered BU Delivery Procedure

July 2012

doc.: IEEE 802.11-12/0831r0

Submission

July 2012


Downlink Buffered BU Delivery Example

• After all awakened STAs exchanged PS-Poll/Trigger and ACK frames, the AP broadcasts a slot assignment frame which includes estimated downlink buffered BU transmission time for STAs.

– Details on the new management frame format is TBD.

Beacon Interval

RAW1 (paged STAs only)

P

• P: Poll• D: Data (APSTA)• D: Data (STAAP)• A: ACK• B : Broadcast

RAW2 (paged STAs only)

DP P

1 0 1 0 0 1 0 0 1 0

TIM bitmap (4 AID bits out of 10 bits are set to 1)

D D

AID: 1 2 3 4 5 6 7 8 9 10

AID1 AID3 AID9 AID1 AID3 AID9

B

doc.: IEEE 802.11-12/0831r0


Uplink Frame Delivery Procedure

• AP may allow a STA/group-of-STA to transmit an uplink frame anytime.

• AP may assign to each STA/group-of-STA a channel access slot at which the STA is allowed to contend through a Beacon frame

– STA wakes up at TBTT and it listens to a Beacon frame

– STA determines its channel access slot through the Beacon frame

– STA starts to access the channel not earlier than the slot boundary of its channel access slot; access is based on EDCA.

• When requested by a STA, AP may assign to the STA a channel access slot at which the STA is allowed to contend, at association or later through a management frame exchange

– STA starts to access the channel not earlier than its slot boundary of its channel access slot; access is based on EDCA.

July 2012

doc.: IEEE 802.11-12/0831r0

Submission

STA2 STA2

July 2012


• At association (or later through a management exchange) AP indicates to a STA a time interval at which the STA is allowed to contend– Time may be defined as a periodic interval

– Offset may be indicated with respect to a given beacon time

– Signaling ‘similar’ to FMS

– Example1

- Example2

STA4, 5

Beacon Beacon

STA3

STA6,7,8,9,10

Beacon Beacon

STA1,2,3,4,5

STA4, 5STA3

Uplink Frame Delivery Example

doc.: IEEE 802.11-12/0831r0


Conclusion

• 11ah use case includes a large outdoor network– Many stations at the edge of the coverage area could be hidden to each other

– Bits set in the TIM element may trigger collisions between the hidden nodes

• When hidden nodes are present in the network, spreading the uplink channel accesses over a much longer period of time significantly reduces the collisions – Some simulation results are shown in [1].

• In this joint contribution, we propose a general procedure for an uplink channel access– Detail about how the STA determines its channel access slot is TBD.

July 2012

doc.: IEEE 802.11-12/0831r0


References

[1] 802.11-12/0606r0, Uplink Channel Access

[2] 802.11-12/0329r0, Group Synchronized DCF

[3] 802.11-12/0823r0, Target Wake Time

[4] 802.11-12/0840r0, AP assisted medium synchronization

July 2012

doc.: IEEE 802.11-12/0831r0


Straw Poll 1

• Do you support to include the uplink channel access protocol of slide 8 in the TGah spec framework document?

July 2012

doc.: IEEE 802.11-12/0831r0


Straw Poll 2

• Do you support to include the downlink buffered BU delivery procedure of slide 11 in the TGah spec framework document?

July 2012

doc.: IEEE 802.11-12/0831r0


Straw Poll 3

• Do you support to include the uplink frame delivery procedure of slide 13 in the TGah spec framework document?

July 2012

doc.: ieee 802.11-12/0831r0 submission july 2012 yongho seok, lg electronicsslide 1 uplink channel...

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