November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 1Submission

Begonya Otal, Job Oostveen, Joerg Habetha, Monisha Ghosh, Pen C. Li, Ronald Rietman, Naveen

Kakani, Nico VanWaes, Srinivas Sreemanthula, Yousuf Saifullah, TK Tan, Jon Rosdahl, KyungHun Jang, DJ Lee,

Youngsoo Kim

November 15th, 2004Joerg.Habetha@philips.com

Merged Partial ProposalMerged Partial Proposalto IEEE 802.11 TGn regarding to IEEE 802.11 TGn regarding

Multiple Data Rate and Receiver Multiple Data Rate and Receiver AggregationAggregation

Nokia/Philips/SamsungNokia/Philips/Samsung

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 2Submission

Content

• Problem Statement

• General PPDU Frame Format

• MMRA: Multiple MCS and Receiver Aggregation

• MMRA Feasibility with WWiSE

• Performance evaluation and comparison to Single

MCS Multiple Receiver Aggregation (SMRA)

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 3Submission

Multiple Receiver Aggregation• Increases throughput efficiency significantly• Reduces buffering delay because MPDUs of different receivers

can be aggregated• Receivers will have different link qualities and data rates:

54 Mbps6 Mbps

108 Mbps

• Furthest receiver could limit throughput of all other stations Aggregation of different Modulation and Coding Schemes

(MCS)

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 4Submission

General PPDU Format

• HT-SIG contains Multiple MCS and Receiver Aggregation (MMRA) Part

• HT-SIG1 indicates presence and MCS of the following HT-SIG MMRA Part

• HT-SIG MMRA Part has variable Length and MCS (Length information on MMRA Part at the beginning of MMRA Part)

• HT-SIG MMRA Part can be transmitted at the minimum MCS of the sub-aggregates or a more robust MCS.

L-STF L-LTFL-

SIGHT-SIG HT LTF HT LTF Data

Legacy CompatiblePreamble

HT Part

HTSTF

HT-SIG1 HT-SIGMMRA Part

Bit that signals presence of MMRA PartMCS MMRA Part

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 5Submission

• Different MCS codes included in HT-SIG MMRA Part for each aggregate

• HT-SIG MMRA Part contains for each MCS: Offset, Nr. Receivers and MAC-addresses of receivers of this MCS

• Power efficiency in PHY (sleeping with sub-aggregate granularity)

• MRAD is kept so as to be compliant with existing TGnSync Multi-Receiver aggregation. Thus, making MMRA as an add on feature with existing TGnSync aggregation.

•MRAD and MPDUs are separated by the MPDU delimiter.

• Example: 2 Rx with MCS1 / 2 Rx with MCS2 / 1 Rx with MCS3

Format of HT-SIG MMRA part & PSDU DATA

HT-SIG MMRA part PSDU DATA

Nr.

Re

ceiv

ers

MC

S2

MA

C A

dd

r.4

MC

S1

MA

C A

dd

r.1

Ra

teO

ffse

t1

MA

C A

dd

r.2

Nr.

Re

ceiv

ers

MA

C A

dd

r.3

Ra

teO

ffse

t2

Nr.

Re

ceiv

ers

MA

C A

dd

r.5

Ra

teO

ffse

t3

MC

S3

Leng

th

MP

DU

1

MP

DU

2

MCS1 MCS2

MR

AD

Mid

ambl

e

Del

imite

r

Del

imite

r

MP

DU

1

MP

DU

2

MR

AD

Del

imite

r

Del

imite

r

Mid

ambl

e

MP

DU

1

MR

AD

Del

imite

r

MCS3

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 6Submission

Fields of HT-SIG MMRA Part

HT-SIG MMRA Part Size (bits) Description

Length 11 Length of the MMRA Part in No. of octets

MCS 8 Code of the MCS scheme, with which the MPDUs

of this MCS sub-aggregate will be transmitted

(present for each MCS in the aggregate)

Rate offset 24 Offset of all MPDUs contained in this MCS sub-

aggregate relative to the beginning of the frame

(present for each MCS in the aggregate)

Number of

receveivers

8 N: Number of receivers with this MCS in the

aggregate (present for each MCS in the aggregate)

MAC adresses N*48 MAC addresses of the receivers (present for each

MCS in the aggregate)

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 7Submission

Power saving & Throughput efficiency

• MMRA allows for efficient power saving scheme• Midambles inside the aggregate enable channel estimation/re-

synchronization after wake-up, if needed• Allows increased throughput by having midambles between

sub-aggregates of different MCS

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 8Submission

Performance evaluation and comparison to Single MCS Multiple

Receiver Aggregation (SMRA)

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 9Submission

• Example: 2 Rx with MCS1 / 2 Rx with MCS2 / 1 Rx with MCS3

• 3 Complete PPDUs (PHY Header+DATA) must be send: one for each PSDU/MCS

• 2 SIFS are required to separate PPDUs at different data rates

• 2 MRADs are required at the beginning of each Aggregate. Note that last MPDU is sent in this case without aggregation because there is just one receiver.

• HT-SIG has no additional fields for the aggregates.

Single MCS Multiple Receiver Aggregation (SMRA)

SIFS SIFS

PSDU1

MP

DU

1

Del

imite

r

MP

DU

2

Del

imite

r

MCS1

MR

AD

MP

DU

3

Del

imite

r

MP

DU

4

Del

imite

r

MCS2

MR

AD

PSDU2 PSDU3

BasicRate

BasicRate

MP

DU

5

MCS3

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 10Submission

Explanation of Analytical Computations Curves•Blue curves are for HT-SIG MMRA Part received

at basic rate (6 Mbps)

•Purple curves are for HT-SIG MMRA Part received at the minimum rate of all aggregates (MCSmin)

•Blue and Purple curves are twice performed, once with a long midamble of 8 usec and once with a midamble of 4 usec

• Red curves is based on TGn Sync MRA, named SMRA

• MRAD from SMRA is sent at basic rate

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 11Submission

Scenario 1: 5 STA at 3 MCS: 24,54,108 Mbps

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 12Submission

Scenario 2: 15 STA at 3 MCS: 24,54,108 Mbps

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 13Submission

Scenario 3: 10 STA at 5 MCS: 18,24,48,54,108 Mbps

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 14Submission

Scenario 4: 30 STA at 5 MCS: 18,24,48,54,108 Mbps

November 2004 doc.: IEEE 802.11-04/xxx

Pen C. Li, et al, PhilipsSlide 15Submission

Conclusions• Multiple receiver aggregation reduces delay compared to single

receiver aggregation• Aggregates with different MCS may either be aggregated or

sent separately (MMRA versus SMRA)• MMRA is much more power efficient than SMRA• MMRA can be added on top of TGnSync SMRA• For MMRA trade-off between power and throughput efficiency• Chosen MMRA is not only more efficient than SMRA in terms of

power consumption but also in terms of throughput efficiency in most scenarios

• MMRA can be merged with WWiSE HTP Burst, and fills the gap in HTP burst by providing power and throughput efficiency

MMRA should be always preferred over SMRA