doc.: ieee 802.11-10/0496r2 submission a flexible beam training protocol for 60ghz mm-wave...

doc.: IEEE 802.11-10/0496r2

Submission

A Flexible Beam Training Protocol for 60GHz mm-Wave Communication (TGad)

Date: 2010-05-18Authors:

Name Affiliations Address Phone email

Junyi Wang NICT 3-4 Hikarino-oka, Yokosuka, Japan

+81-46-847-5110 [email protected]

Tuncer Baykas NICT [email protected]

Chin Sean Sum NICT [email protected]

Zhou Lan NICT [email protected]

Chang Woo Pyo NICT [email protected]

M Azizur Rahman NICT [email protected]

Hiroshi Harada NICT [email protected]

May 2010

Slide 1 Junyi Wang, NiCT

doc.: IEEE 802.11-10/0496r2

Submission

Abstract

Overview of beamforming (BF) related contributions for 802.11ad and suggestions for BF proposal based on those contributions.

May 2010


doc.: IEEE 802.11-10/0496r2

Submission

Why BF?

• Comparing with 2.4GHz/5GHz WLAN, a high propagation loss in 60GHz link budget shall be compensated with antenna gain.

• Interferences from other systems can be mitigated with BF techniques.

• Coexistence capability can also be improved with directional transmission.

May 2010

Junyi Wang, NiCTSlide 3

doc.: IEEE 802.11-10/0496r2

Submission

Overview of BFcontributions in TGad (1/2)• In 09/355r1, a BF protocol is specified on the top of multiple PHY

modes.

• In 09/0572r0, the authors show that in 60GHz, most usages (07/2988r4) require directional communication in order to meet link budget requirements.

• In 09/0572r0, the authors also believe that TGad should reuse as much as possible from 802.11+amendments.

• In 09/1153r0, the authors conclude that BF is one of the most important features in the TGad 60GHz specification and will be decisive in enabling successful 60GHz products.

May 2010


doc.: IEEE 802.11-10/0496r2

Submission

Overview of BFcontributions in TGad (2/2)• In 09/1153r0, the authors summary the BF requirements in TGad

– One BF protocol for all usages/scenarios– The BF protocol shall support different antenna types and does not assume

antenna reciprocity– The BF protocol shall allows fast BF link (re-)establishment and tracking– The BF protocol should accommodate devices/usages with different levels of

complexity– The protocol should supports pre-network entry and post-network entry BF

• In 10/0231r3, the authors propose to use 802.11a/b/g/n to assistant 802.11ad for signalling.

• In 10/430r0 and 10/450r1, the authors propose beamforming protocol for sector sweeping, beam refinement and beam tracking

• In 10/493r0, the authors propose to find the optimum weight vector for beamforming.

May 2010


doc.: IEEE 802.11-10/0496r2

Submission

Network model

May 2010


Infrastructure mode Ad-hoc mode

• In infrastructure mode, a beamformed link shall be set up between Access Point (AP) and any Station (STA).• In Ad-hoc mode, a beamformed link shall be set up between any two STAs.

In 60GHz WLAN, both of them shall support CSMA/CA and TDMA mode

doc.: IEEE 802.11-10/0496r2

Submission

May 2010


BF model

• The objective of the proposed BF is to find the best transmit and receive antenna weight vector from the pre-defined codebook through MAC operation in order to optimize a cost function that measures the link quality metric. In this proposal, signal to interference plus noise ratio (SINR) is used as the metric.

STA1transmitter

STA2receiver

STA1receiver

STA2transmitter

STA1's transmit weigh vector STA2's receive weigh vector

STA1's receive weigh vector STA2's receive weigh vector

RFChannel

1

2

tM

1

2

rM

1

2

tN

tN

1

2

Phase shifter

doc.: IEEE 802.11-10/0496r2

Submission

Basic assumptions for BF

• All STAs shall support one or more directional antenna patterns, which are generated by the pre-defined beam codebooks. – A beam codebook is a matrix where each column specifies a BF

weight vector. Each column also specifies a pattern.

• Either of the following ways shall be supported for BF signaling (including BF request/response). – At least AP supports omni (or quasi-omni) transmission with low date

rate by using advanced modulation and coding scheme that compensates for the lack of antenna gain.

– All BF capable STAs support 2.4GHz/5GHz WLAN (IEEE 802.11a/b/g)

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doc.: IEEE 802.11-10/0496r2

Submission

Initial status• The proposed on-demand BF starts from either of

following initial status by acquiring synchronization with AP

May 2010


AP

STA 1

STA 2

STA 3

By switching directional pattern to acquiring timing in 60Ghz

AP

STA 1

STA 2

STA 3

2.4GHz/5GHz Omni

Through 2.4GHz/5GHz omni antenna to acquiring time for 60GHz

doc.: IEEE 802.11-10/0496r2

Submission

Beam searching between two STAs

Address 1 (source)

Address 2 (destination)

Address 3(BF target)

BFRqt (1) STA1 AP STA2

BFRsp (1) AP STA2 STA1



BFFdbk (1) STA2 STA1 STA1


May 2010


CSMA/CA based CSMA/CA or TDMA based CSMA/CA or TDMA based

AP

STA 1

STA 2

Other STA

BFRqt(1)

BFRsp(1)

NAV

SIFS

SIFS

NAV

Training

BFFdbk(1)SIFSSIFS Training

SIFSBFFdbk

(2)

SIFS ACKBFRqt

(2)

BFRsp(2)SIFS

SIFS

Initial Training Feedback and channel check

doc.: IEEE 802.11-10/0496r2

Submission

Beam refinement

May 2010


Address 1 (source)









AP

STA 1

STA 2

BFRqt(1)

BFRsp(1)SIFS

SIFS

Training

BFFdbk(1)SIFSSIFS Training

SIFSBFFdbk

(2)

SIFS ACKBFRqt(2)

SIFSBFRsp

(2)SIFS

Initial(may be omitted when

“more training” is set to 1

Training Feedback and channel check


“More training” =1

doc.: IEEE 802.11-10/0496r2

Submission

Beam searching between AP and STA

May 2010


Address 1 (source)



BFRqt (1) STA1 AP AP


BFFdbk (1) AP STA1 STA1

BFFdbk (2) STA1 AP AP

BFRqt (2) AP STA2 STA2

AP

STA 1

STA 2

Other STA

BFRqt(1)

BFRsp(1)SIFS SIFS

NAV

Training SIFS

SIFS

BFFdbk(2)

Training SIFS ACKBFRqt

(2)BFFdbk

(1)SIFS

Initial Training Feedback and channel check


doc.: IEEE 802.11-10/0496r2

Submission

Initial substage• Function– Handshaking for BF– Exchange BF capability

• If the beam searching is performed in TDMA service period, then the initial BF capability has been exchanged during association or by beacon, the “BF capability” field in initial BFRqt or BFRsp command shall be empty.

– Set network allocation vector NAV for other devices if BF is performed in CSMA/CA mode

• Transmission – The BFRqt and BFRsp shall be sent in CSMA/CA mode.– AP shall send or receive command with (1) omni/quasi-omni pattern with advanced

modulation and coding rate to compensate the propagation loss; or (2) in 2.4GHz or 5GHz WLAN.

– The handshaking period may be omitted in beam refinement stage if the field “More training” is set to 1 in the BFfdbk command.

• BFRqt/BFRsp Frame– BFRqt/BFRsp Frame is control frame with framebody information shown in next

page.

May 2010


doc.: IEEE 802.11-10/0496r2

Submission

BFRqt/BFRsp frame format

• Address 1: the address of the source• Address 2: the address of the destination• Address 3: the address of the BF target• Rqt/Rsp: Set to 1 when it is BFRqt command, otherwise set to 0• Training mode: set 1 if BF is to perform in reserved service period (SP), set to 0 otherwise.

• Quasi-omni capable : Set to 1 when the STA is quasi-omni capable, otherwise set to 0.

• BF capable: Set to 1 when the STA is BF capable.

• # of Tx beams: Number of transmit beam pattern of the command transmitter. • # of Rx beams: Number of receive beam pattern of the command transmitter.• Searching /Refinement: set to 1 if the stage is searching stage, otherwise set to 0.

May 2010


FrameControl

Duration Address 1 Address 2 Address 3

BF capable# of Tx patterns

# of Rx patterns

Quasi-omnicapable

Rqt/ RspBF

capabilitySearching/

RefineFCS

Training mode

doc.: IEEE 802.11-10/0496r2

Submission

Training substage(1/2) • Training procedure in beam searching substage

– As shown in Figure (a) Supposing beamformer has M directions, beamformee has N directions. Each training period is composed of M cycles of N repetitions. Each cycle shall be sent from each of beamformer’s transmit directions. The repetitions shall be received by each of receive direction of beamformee.

• Training in Beam refinement substage – Cover the same space of the selected pattern with more now narrower beams, and

select the best beam pair among all transmit and receive beam combinations.

– Beam refinement substage may repeat to further narrow down the beam until both of STAs are satisfied.

May 2010


STA 1

[TS2 TS1]

Transmit TSs during cycle 1

STA 2

Transmitdirection 1

Transmitdirection 2

Cycle 1Cycle 2

Receive direction 1

Receivedirection 2

[TS2 TS1]

Transmit TSs during cycle 2

STA1STA 3Transmit beam 1

Transmit beam 2

Receive beam 1

Receive beam 2

(a) Beam training (b) Beam refinement

doc.: IEEE 802.11-10/0496r2

Submission

Training substage(2/2)• Training starting time

– The training shall start after receiving BFrsp command following by a “SIFS” interval in CSMA/CA mode or start at the beginning of a reserved service period in TDMA mode

• Training sequences – Training sequences is a control frame with following framebody

• Tx pattern ID: the pattern ID in which the training sequences is sent

• Training sequence counter: the index of training sequences

• Total training sequences : Total training sequences to be sent continuously.

– The PLCP preamble can used as the training sequences for each direction, the “long training sequence ” (for channel estimation) in the preamble can be used for SNR estimation.

May 2010


FrameControl

Tx pattern ID

Training sequence counter

Total training

sequencesFCS

doc.: IEEE 802.11-10/0496r2

Submission

Feedback substage• Function– Feed back the selected best transmit pattern

– Recheck the beamformed channel

• Transmission – The BFFdbk command can be sent in CSMA/CA mode, or in a TDMA service period.– The first feedback after first training period shall be sent in all transmit direction of a STA

so that beamformee may receive at least any one of them.

• BFFdbk Frame– BFFdbk Frame is control frame with the following framebody information.

• Address 1: the address of the source

• Address 2: the address of the destination

• Address 3: the address of the BF target

• Best pattern ID: the index of the best pattern

• SNR of best pattern: the SNR of the best pattern, for transmitter to select proper modulation and coding scheme.

• More training: Set to1 if following is a beam refinement stage, otherwise set to 0

• BF capability: same with the field in BFrqt/BFrsp, however may be omitted if “More training” is set to 0.

May 2010


More training

FrameControl

Duration Address 1 Address 2 Address 3Best

pattern IDSNR of best

patternFCS

BF capability

doc.: IEEE 802.11-10/0496r2

Submission

Some rules for some special cases

1. STA1 is BF capable, however STA2 is not– STA2 shall help STA1 finish BF operation by using omni/quasi-

omni transmission.

2. STA1 is capable of beam refinement, however STA2 is not.– STA2 could not refine its pattern into finer beams. STA2 shall

use his latest found pattern to help STA1 finish BF operation, in this case, STA2 shall set the # of Tx beam and # of Rx beam to 1.

May 2010


doc.: IEEE 802.11-10/0496r2

Submission

Beam tracking

• Why beam tracking– Possible channel variation

– Possible block

• Beam tracking– Beam tracking is performed together with data streaming

periodically.

– The training sequences are attached at the end of data

– the beam for data streaming (called working beam in the following context) and its adjacent beams ( and the wider pattern which cover the working beam and its adjacent pattern may be tracked prepared for contingencies of the working beam’s blocking)

May 2010


Data Data Time

doc.: IEEE 802.11-10/0496r2

Submission

Conclusions• The proposed BF protocol is beam codebook based proposal, which selects

the best beam pattern from pre-defined beam codebook, and setup a beamformed communication link between any STAs.

• The proposed BF includes full 3 phases, i.e., beam searching, beam refinement and beam tracking.

• The proposed BF protocol supports different level of codebook complexities, no training stage limitation. STAs are able to request further beam refinement as long as they need.

• Beam searching and beam refinement stage can be easily combined and separated, significantly improve the flexibility of BF protocol.

• The proposed BF protocol is available in both CSMA/CA mode and TDMA mode, compliant with the full proposals in TGad, and also compliant with currently implemented IEEE 802.11 MAC.

• The proposed BF protocol can also be extended to support AP directional transmission.

May 2010


doc.: IEEE 802.11-10/0496r2

Submission

References• IEEE Std 802.15.3c™-2009

• 11-07-2988-04-00-00ad Wi-Fi Alliance (WFA) VHT Study GroupUsage Models

• 11-09-0355-01-00-00ad IEEE 802.15.3c Beamforming overview

• 11-09-0572-00-00-00ad MAC Channel Access in 60 GHz

• 11-09-1153-00-00-00ad Motivation and Requirements on 60 GHz Beamforming

• 11-10-0259-02-00-00ad 802.11ad New Technique Proposal

• 11-10-0430-00-00-00ad NT-11 Beamforming Introduction

• 11-10-0450-01-00-00ad NT-12 on Beamforming (BRP)

• 11-10-0493-00-00-00ad Beamforming training for IEEE 802.11ad

May 2010


doc.: ieee 802.11-10/0496r2 submission a flexible beam training protocol for 60ghz mm-wave...

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