Post on 03-Jan-2016
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