Doc.: IEEE 802.11-04/0929r1 Submission August 2004 Patrik Eriksson et. al., WaveBreaker ABSlide 1 A...

August 2004

Patrik Eriksson et. al., WaveBreaker AB

Slide 1

doc.: IEEE 802.11-04/0929r1

Submission

A “High Throughput” Partial Proposal

Patrik Eriksson, Anders Edman, Christian KarkWavebreaker AB, Norrkoping, Sweden

[email protected]

Scott Leyonhjelm, Mike Faulkner, Melvyn Pereira,Jason Gao, Aaron Reid,Tan Ying,Vasantha Crabb.

Australian Telecommunication Co-operative Research Centre, Melbourne, Australia.

[email protected]

August 2004


Slide 2

doc.: IEEE 802.11-04/0929r1

Submission

Presentation Outline

• Proposal Executive Summary• Proposed Frame Format • Proposed PHY Design • Comparison Criteria• Conclusion

August 2004


Slide 3

doc.: IEEE 802.11-04/0929r1

Submission

Proposal Executive Summary• Fully backward compatible with 802.11a/g

– All enhancements are simple extensions to 11a/g OFDM structure.– STS and LTS sequences are used in conjunction with progressive cyclic

delay per antenna• Higher Data Throughput due to combination of PHY technologies

– MIMO-OFDM - Spatial Multiplexing, up to 3 transmit spatial streams (mandatory), 4 spatial streams (optional)

– Fast Rate adaptation on a per stream (mandatory) or a per subgroup (optional) level

– Higher order modulation - 256QAM (mandatory)• Higher Data Throughput due to combination of MAC enhancements

– Frames with NO short and long training sequences (mandatory)– Frame aggregation (mandatory)– Shorter SIFS, down to 8 us. (Optional)

• Minimising Hardware Complexity– Frame format designed to increase available time for inverting channel

estimate.

August 2004


Slide 4

doc.: IEEE 802.11-04/0929r1

Submission


• Proposal Executive Summary• Proposed Frame Format • Proposed PHY Design • Comparison Criteria• Conclusion

August 2004


Slide 5

doc.: IEEE 802.11-04/0929r1

Submission

Proposed Frame Format3 new MIMO frame types are proposed:• MIMO - Type 1 frames with Training.

– Re-Synchronisation – Note that the STS, LTS and Sig2 sequence can be received by legacy equipment.– S3 is positioned to increase time allowed for calculating and inverting channel estimate

• MIMO - Type 2 frames without Training. – Preferred for Data carrying frames

• MIMO – Type 3 frames with Training. – RTS/CTS frames in 5GHz band– Note that the STS, LTS and Sig and Data sequence can be received by legacy equipment. – S3 is positioned to increase time allowed for calculating and inverting channel estimate

802.11n MIMO - Type 1


STS1 LTS1 S2 LTS1a LTS1b LTS1c




S3

S3

S3

S3

D1

D1

D1

D1

D2

D2

D2

D2

Dn

Dn

Dn

Dn

S3

S3

S3

S3

D1

D1

D1

D1

D2

D2

D2

D2

Dn

Dn

Dn

Dn


S2 LTS1a LTS1b LTS1c




S3

S3

S3

S3

D1

D1

D1

D1

D2

D2

D2

D2

STS1 LTS1 Sigi

STS2 LTS2 Sig

STS3 LTS3 Sig

STS4 LTS4 Sig

D1

D1

D1

D1

D2

D2

D2

D2

Dn

Dn

Dn

Dn

802.11a OFDM Frame format STS LTS Sig D1 D2

August 2004


Slide 6

doc.: IEEE 802.11-04/0929r1

Submission

Proposed Frame Format802.11a compatible

Sig2 LTS1a LTS1b LTS1c




Sig3

Sig3

Sig3

Sig3

D1

D1

D1

D1

D2

D2

D2

D2

STS1 LTS1 Sig

STS2 LTS2 Sig

STS3 LTS3 Sig

STS4 LTS4 Sig

D1

D1

D1

D1

D2

D2

D2

D2

Dn

Dn

Dn

Dn

MIMO part of frame

Length field faked Sig symbol MIMO data length

Sig2 Symbol - Specify MIMO transmission Mode•Adaptive Loading Mode•MIMO mode•Indicate if Sig3 and Data symbols are present

Sig3 Symbol – supports MIMO transmission•Reverse link CSI info•Data Rate used in transmission•Data length•Request for retraining

R4 – indicates MIMO

Extra time for inverting CE

Type 2 MIMO Frame (DATA)

August 2004


Slide 7

doc.: IEEE 802.11-04/0929r1

Submission

Proposed Frame Format

Type3AP:

STA: Type3

Type2

Type1

Time

Type1 Type2

Training required for initially establishing fast rate adaptation

Data carrying with no Trainingsequence

Request for Trainingsequence

Used for •Re-transmission•Re-synchronising during a RTS/CTS transmission, and•Extending the duration of the transmission (CTS to self)

Example ofRTS/CTS frame transfer:

RTS

CTS

Data

ACK ACK

Data Training

Training

n*4 us

SIFS= 8-16us

Updated rateinformation

August 2004


Slide 8

doc.: IEEE 802.11-04/0929r1

Submission

Proposed Frame Format

• Proposed frame format compared to 802.11a – MAC Efficiency 61% vs 47% – PSDU Size = 1.5kbyte

• Frame Aggregation – 9kbyte PSDU size– MAC efficiency >80%

August 2004


Slide 9

doc.: IEEE 802.11-04/0929r1

Submission

Proposed Frame FormatTo Achieve Goodput of >100Mbps for PER 10%, PHY average rate =144Mbps• Single Frame Transmission Mode

– PSDU Size = 5kbyte packet • RTS/CTS Transmission Mode

– Packet Size > 2kbyte– Transmission Length = 10kbyte

• Frame Aggregation– Increases MAC efficiency– Proposed max. PSDU 16kbyte

August 2004


Slide 10

doc.: IEEE 802.11-04/0929r1

Submission

Proposed Frame FormatImplementation Details of the Frame Format proposal• Channel Models in 802.11n are slowly moving (low Doppler)

– Channel sufficiently stable for at least 50 symbols (MSE <-35dB)– Channel F with 40kph Doppler Component

• Type 2 packets have NO training sequences– Initial STS/LTS sets up Timing grid – Transmissions start at 4us intervals – Receiver uses fast power detection

algorithms to determine if packet (sig3 symbol) is present or not

– Frequency offset and sampling time offsets must flywheel over non-transmission periods

• Implementation Requirements– Time, frequency offsets tracked via 4

pilots– Channel Tracking

August 2004


Slide 11

doc.: IEEE 802.11-04/0929r1

Submission


• Proposal Executive Summary• Proposed Frame Format • Proposed PHY Design• Comparison Criteria• Conclusion

August 2004


Slide 12

doc.: IEEE 802.11-04/0929r1

Submission

Proposed PHY Design

Parallel Spatial Multiplexing Architecture• Scalable architecture - supports up to 3 (mandatory) or 4 (optional) antennas • The mapping function expanded to include 256QAM• Cyclic Delay is implemented with a progressive 1 sample delay /per antenna• Fast Rate Adaptation

Demux

Data Bits

Scramble

Encode

Encode

Encode

Encode Punct

Punct

Punct

Punct

Inter. Map

Inter.

Inter.

Inter.

FFT CP Cyclic Delay

To DACs

Map FFT CP Cyclic Delay



Adaptive Loading Info from Sig3 Symbol ‘CSI’ field

Mux

STS and LTS Preambles

Mux

Pilots

August 2004


Slide 13

doc.: IEEE 802.11-04/0929r1

Submission

Proposed PHY Design

Fast Rate Adaptation Concept => Higher Average Data Throughput

• Based on Closed loop feedback of CSI transported by ACK frame• Optimises Data rate to channel condition on a per packet basis• Low implementation cost vs High performance gain• Small impact on MAC efficiency

– 4 bits per spatial stream• Overcomes spatial multiplexing singularity in LOS conditions

– Naturally falls back to transmission of a single stream

August 2004


Slide 14

doc.: IEEE 802.11-04/0929r1

Submission

Proposed PHY Design

• Rate Adaptation Concept– The STA determines the maximum rate per layer (mandatory) or subgroup of

carriers (optional) and this is communicated back to the AP, and vice-versa. – Adaptive rate can vary from 0Mbit/s through to 72Mbits/s on a per layer basis.– Fast Adaptation handled at PHY layer, reported to MAC

Punct/ MapData

Bits

Tx

Channel Estimation

Rx

Data Bits

Forward Link

SNR (Link Margin/layer)

Calculate Maximum Rate Possible on a per layer basis

Decode Sig3 Symbol ‘Rev

CSI’ field

Reverse Link Encode Sig3

Symbol ‘Rev CSI’ field

August 2004


Slide 15

doc.: IEEE 802.11-04/0929r1

Submission

Proposed PHY Design • Short Training Sequences

– 802.11a STS transmitted on each stream– Cyclic delay ensures good performance characteristics for AGC function

• Long Training Sequences– Based on current LTS definitions– Orthogonality between TX antennas achieved via Cyclic Delay and ‘Phase Loading’– Channel Estimation achieved by combining received LTS’s

TX1

TX2

TX3

STS LTS LTS LTS

STS LTS LTS*exp (j/3) LTS*exp (j2/3)

STS LTS LTS*exp (j2/3) LTS*exp (j/3)

August 2004


Slide 16

doc.: IEEE 802.11-04/0929r1

Submission

Proposed PHY Design

• For >100 Mbps Goodput @ 10m: 3 data streams required• For >3*3 MIMO : Channel estimation and equalisation begins to dominate• Analog increases slightly less than linear due to reuse of functions

2*2 MIMO

802.11a

3*3 MIMO

4*4 MIMO

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0 20 40 60 80 100 120 140 160

Goodput with 20MHz, CC58, Chan. B, RTS/CTS frame transmission (Mbps)

Rel

ativ

e DSP C

ompl

exity

August 2004


Slide 17

doc.: IEEE 802.11-04/0929r1

Submission



August 2004


Slide 18

doc.: IEEE 802.11-04/0929r1

Submission

Comparison Criteria –CC58• RTS/CTS frame transmission mode achieves a goodput of more than 100Mbps, • The single frame transmission mode achieves a maximum goodput of 80Mbps when

the average PHY data rate is 288Mbps !. To get >100Mbps– With frame aggregation a 5.5kbyte packet size transmitted at a average PHY data rate of

144Mbps – With channel bonding (optional) the average PHY data rate is increased by a factor 1.8

Configuration Average PHY Data rate to achieve Goodput

>100Mbps

bps/Hz

Single Frame Mode N.A. N.A. 2*2 MIMO, Channel B RTS/CTS Mode 144Mbps 7.2

Single Frame Mode N.A. N.A. 3*3 MIMO, Channel B,D RTS/CTS Mode 144-216Mbps 7.2-10.8

Single Frame Mode N.A. N.A. 4*4 MIMO, Channel B,D (Optional)

RTS/CTS Mode 144-288Mbps 7.2-14.4

Just! with no impairments

August 2004


Slide 19

doc.: IEEE 802.11-04/0929r1

Submission

Comparison Criteria• CC59 –AWGN Channel

– Observation : the capacity is a linear function of the number of transmit data streams.

August 2004


Slide 20

doc.: IEEE 802.11-04/0929r1

Submission

Comparison criteria• CC80- The modifications required for a legacy

802.11 PHY are;– The scalable architecture supports up to 3 (mandatory)

or 4 (optional) antennas – Rate adaptation modifies the puncturing and

Constellation Mapping on a stream basis, – Include 256 QAM– Cyclic Delay implemented with a progressive 1 sample

delay /per antenna– The LTS preambles are modified versions of the

802.11a/g defined sequences

August 2004


Slide 21

doc.: IEEE 802.11-04/0929r1

Submission



August 2004


Slide 22

doc.: IEEE 802.11-04/0929r1

Submission

Conclusion – Key Features

• Higher Data Throughput due to combination of PHY technologies– MIMO-OFDM – 1 to 3 data streams using Spatial

Multiplexing – Rate Adaptation– Higher order modulation – 256QAM

• Higher Data Throughput due to combination of MAC enhancements– Frames with NO training sequences– Frame aggregation – up to 16kbytes/packet

August 2004


Slide 23

doc.: IEEE 802.11-04/0929r1

Submission

Conclusion• Backward Compatibility is ensured by

– Operation within a 20MHz bandwidth with the same 802.11a/g spectral mask.

– Single and RTS/CTS frame transmission modes are fully compatible with legacy 802.11a/g devices.

• All Low Functional Requirements are met• Low Overhead Frame formats to increase MAC efficiency• 100Mbps Goodput @ 10m achieved when

– 20MHz and >=3 transmit data streams– > 144Mbps Average PHY data rate – With Rate Adaptation!

Doc.: IEEE 802.11-04/0929r1 Submission August 2004 Patrik Eriksson et. al., WaveBreaker ABSlide 1 A...

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