doc.: ieee 802.11-04/0929r1 submission august 2004 patrik eriksson et. al., wavebreaker abslide 1 a...
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doc.: IEEE /0929r1 Submission August 2004 Patrik Eriksson et. al., WaveBreaker ABSlide 3 Proposal Executive Summary Fully backward compatible with a/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.TRANSCRIPT
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
Scott Leyonhjelm, Mike Faulkner, Melvyn Pereira,Jason Gao, Aaron Reid,Tan Ying,Vasantha Crabb.
Australian Telecommunication Co-operative Research Centre, Melbourne, Australia.
August 2004
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
Slide 4
doc.: IEEE 802.11-04/0929r1
Submission
Presentation Outline
• Proposal Executive Summary• Proposed Frame Format • Proposed PHY Design • Comparison Criteria• Conclusion
August 2004
Patrik Eriksson et. al., WaveBreaker AB
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
802.11n MIMO - Type 2
STS1 LTS1 S2 LTS1a LTS1b LTS1c
STS2 LTS2 S2 LTS2a LTS2b LTS2c
STS3 LTS3 S2 LTS3a LTS3b LTS3c
STS4 LTS4 S2 LTS4a LTS4b LTS4c
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
802.11n MIMO - Type 3
S2 LTS1a LTS1b LTS1c
S2 LTS2a LTS2b LTS2c
S2 LTS3a LTS3b LTS3c
S2 LTS4a LTS4b LTS4c
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
Patrik Eriksson et. al., WaveBreaker AB
Slide 6
doc.: IEEE 802.11-04/0929r1
Submission
Proposed Frame Format802.11a compatible
Sig2 LTS1a LTS1b LTS1c
Sig2 LTS2a LTS2b LTS2c
Sig2 LTS3a LTS3b LTS3c
Sig2 LTS4a LTS4b LTS4c
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
Slide 11
doc.: IEEE 802.11-04/0929r1
Submission
Presentation Outline
• Proposal Executive Summary• Proposed Frame Format • Proposed PHY Design• Comparison Criteria• Conclusion
August 2004
Patrik Eriksson et. al., WaveBreaker AB
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
Map FFT CP Cyclic Delay
Map FFT CP Cyclic Delay
Adaptive Loading Info from Sig3 Symbol ‘CSI’ field
Mux
STS and LTS Preambles
Mux
Pilots
August 2004
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
Slide 17
doc.: IEEE 802.11-04/0929r1
Submission
Presentation Outline
• Proposal Executive Summary• Proposed Frame Format • Proposed PHY Design• Comparison Criteria• Conclusion
August 2004
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
Slide 21
doc.: IEEE 802.11-04/0929r1
Submission
Presentation Outline
• Proposal Executive Summary• Proposed Frame Format • Proposed PHY Design• Comparison Criteria• Conclusion
August 2004
Patrik Eriksson et. al., WaveBreaker AB
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
Patrik Eriksson et. al., WaveBreaker AB
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!