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A “High Throughput” Partial Proposal

A “High Throughput” Partial Proposal. Patrik Eriksson, Anders Edman, Christian Kark Wavebreaker AB, Norrkoping, Sweden patrik.eriksson@acreo.se

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A “High Throughput” Partial Proposal

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  1. A “High Throughput” Partial Proposal Patrik Eriksson, Anders Edman, Christian Kark Wavebreaker AB,Norrkoping, Sweden patrik.eriksson@acreo.se Scott Leyonhjelm (Editor), Mike Faulkner, Melvyn Pereira,Jason Gao,Aaron Reid,Tan Ying,Vasantha Crabb. Australian Telecommunication Co-operative Research Centre, Melbourne, Australia. scott.leyonhjelm@vu.edu.au Patrik Eriksson et. al., WaveBreaker AB

  2. Presentation Outline • Proposal Executive Summary • Proposed PHY Design • Proposed Frame Format • Comparison Criteria • Conclusion Patrik Eriksson et. al., WaveBreaker AB

  3. Proposal Executive Summary • Fully backward compatible with 802.11a/g • 20MHz with 802.11a/g mask • 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 antennas (mandatory), 4 antennas (optional) • Fast Adaptive Loading - Rate adaptation on a per layer (mandatory) or per a subgroup (optional) level • Higher order modulation - 256QAM • Higher Data Throughput due to combination of MAC enhancements • Shorter SIFS, down to 8 us. • Frames with NO short and long training sequences • Frame aggregation • Minimising Hardware Complexity • Frame format designed to increase available time for inverting channel estimate. Patrik Eriksson et. al., WaveBreaker AB

  4. Presentation Outline • Proposal Executive Summary • Proposed PHY Design • Proposed Frame Format • Comparison Criteria • Conclusion Patrik Eriksson et. al., WaveBreaker AB

  5. Demux Encode Punct Inter. Map Mux FFT CP Mux Cyclic Delay Encode Punct Inter. Map FFT CP Cyclic Delay Data Bits Scramble To DACs Encode Inter. Map FFT CP Cyclic Delay Punct Encode Punct Inter. Map FFT CP Cyclic Delay Adaptive Loading Info from Sig3 Symbol ‘CSI’ field Pilots STS and LTS Preambles 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 • Adaptive Loading (Rate Adaptation) Patrik Eriksson et. al., WaveBreaker AB

  6. Forward Link Punct/ Map Channel Estimation Data Bits Data Bits Tx Rx SNR (Link Margin/layer) Calculate Maximum Rate Possible on a per layer basis Reverse Link Decode Sig3 Symbol ‘Rev CSI’ field Encode Sig3 Symbol ‘Rev CSI’ field Proposed PHY Design • Adaptive Loading (Rate Adaptation) • 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. • Adapts the Puncturing and Constellation Mapping on a layer basis. • Adaptive rate can vary from 0Mbit/s through to 72Mbits/s on a per layer basis. • Fast Adaptation handled at PHY layer Patrik Eriksson et. al., WaveBreaker AB

  7. Proposed Frame Format PHY Digital complexity – N layers vs 1 layer (11a) • ~N times complexity for most baseband processing blocks (e.g. filter, FFT, frequency correction, mapping, demapping, decoding) • energy per bit for these parts remain constant compared to 11a. • >N times complexity for Channel Estimation & Equalisation: • approx the same as for FFT b;lock for up to 3*3 MIMO system. • The increased length of payload, and transmission of frames without preambles keep the power cost for this operation at a reasonable level. • Sig3 symbol placement between last preamble and data increases available time for computation with one symbol period. This reduces the required complexity of the logic for this function. Analog Area and Power – N layers vs 1 layer (11a) • <N times Area and Power consumption as some units are reused for all channels Summary for N=3; • ~4 times 11a for Digital baseband computational complexity • ~2.5 times 11a for Analog area and power consumption. Patrik Eriksson et. al., WaveBreaker AB

  8. Presentation Outline • Proposal Executive Summary • Proposed PHY Design • Proposed Frame Format • Comparison Criteria • Conclusion Patrik Eriksson et. al., WaveBreaker AB

  9. 802.11a OFDM Frame format 802.11g OFDM Frame format 802.11g DSSS Frame format 802.11n MIMO - Type 1 802.11n MIMO - Type 2 802.11n MIMO - Type 3 Sig2 LTS2 STS2 LTS1c LTS1b LTS1 Sig2 LTS2a STS1 Sig3 Ext LTS1a LTS2b LTS3 STS3 D1 Sig2 LTS3a LTS3b LTS3c STS4 LTS4 Sig2 LTS4a LTS4b LTS4c Sig3 LTS2c D1 Sig2 LTS1a D2 Dn Sig3 Sig3 Sig3 Dn Dn D2 Dn D1 D2 D2 D2 LTS1b D1 D1 D1 D1 D1 D2 D2 D2 D2 Dn Dn Dn Dn Sig3 Sig3 Sig3 LTS1c STS3 LTS2c Sig2 LTS3a LTS3b LTS3c Sig2 LTS4a LTS4b LTS4c Sig3 Sig3 Sig Sig3 Sig2 D1 D2 LTS2 STS2 Sig LTS1 STS1 D1 D2 D2 D2 D1 D1 Sig3 D1 STS4 Dn LTS2b LTS4 Sig D1 D1 D1 D1 D2 D2 D2 D2 Dn Sig Dn Dn STS LTS Sig D1 D2 Preamble Head STS LTS Sig D1 D2 LTS3 LTS2a Proposed Frame Format 3 new MIMO frame types are proposed: • MIMO - Type 1 frames with Training. Note that the STS, LTS and Sig2 sequence can be received by legacy equipment. • MIMO - Type 2 frames without Training. Note that time, frequency & channel tracking algorithms will be required. • MIMO – Type 3 frames with Training used only in 5GHz band. Note: Sig3 and Data Symbols can be turned off. Patrik Eriksson et. al., WaveBreaker AB

  10. Proposed Frame Format • Type 3 only – Single MIMO frame transmission • MIMO frames appended to a 11a/g frame => backward compatible with 11a/g frames • contains MIMO training and Data • Sig2 symbol – Indicates MIMO setup • Sig3 symbol – indicates MIMO rates being used and length of MIMO transmission. • Type 3,2 & 1 –RTS/CTS frame transfer • Type 3 • Training required for initially establishing Adaptive Loading • Sig3 symbol – indicates Adaptive Loading rates & Data Length • <Training><Sig3><Data> - increases available time for inverting channel estimate. • Type 2 - Data carrying with no Training Sequence • Type 1 - backward compatible with 11a/g frames, used for • Used on a retransmission • Re-synchronising during a RTS/CTS transmission, and • Extending the duration of the transmission (CTS to self) • SIFS an take a value between 8 to 16us • receiver must be ready to receive after 8us but a transmitter is allowed to wait up to 16us before starting Patrik Eriksson et. al., WaveBreaker AB

  11. Proposed Frame Format To Achieve Goodput of >100Mbps for PER 10%, PHY average rate =144Mbps • Single Frame Transmission Mode • Packet Size = 5.5kbyte packet • RTS/CTS Transmission Mode • Packet Size > 2kbyte • Tranmission Length = 10kbyte • Frame Aggregation • Increases MAC efficiency • Proposed max. 16kbyte packet Patrik Eriksson et. al., WaveBreaker AB

  12. Proposed Frame Format Implementation 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 ST/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 Patrik Eriksson et. al., WaveBreaker AB

  13. Presentation Outline • Proposal Executive Summary • Proposed PHY Design • Proposed Frame Format • Comparison Criteria • Conclusion Patrik Eriksson et. al., WaveBreaker AB

  14. Comparison Criteria • CC51- mandatory • BPSK thru to 256QAM • Rates 0 thru to 72Mbps per layer • 1,2 or 3 transmit antennas • CC42- The short and long training sequences are the same as the 802.11a/g defined training sequences with the following modifications: • Both the STS and LTS sequences have a progressive cyclic delay of 1 sample per antenna applied, see also Appendix A, Section 7.1 • The LTS sequences are also phase loaded on a per antenna basis Patrik Eriksson et. al., WaveBreaker AB

  15. 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 Patrik Eriksson et. al., WaveBreaker AB

  16. Comparison Criteria • CC59 –AWGN Channel • Observation : the capacity is a linear function of the number of transmit antennas. • Each layer had the same rate, even if the adaptive loading algorithm was switched on. Patrik Eriksson et. al., WaveBreaker AB

  17. 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 • The adaptive loading modifies the puncturing and Constellation Mapping on a layer 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 Patrik Eriksson et. al., WaveBreaker AB

  18. Presentation Outline • Proposal Executive Summary • Proposed PHY Design • Proposed Frame Format • Comparison Criteria • Conclusion Patrik Eriksson et. al., WaveBreaker AB

  19. Conclusion – Key Features • Higher Data Throughput due to combination of PHY technologies • MIMO-OFDM – 1 to 3 antennas using Spatial Multiplexing • Rate Adaptation • Higher order modulation – 256QAM • Higher Data Throughput due to combination of MAC enhancements • Shorter SIFS - down to 8 us. • Frames with NO short and long training sequences • Frame aggregation – up to 16kbytes/packet Patrik Eriksson et. al., WaveBreaker AB

  20. 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 Functional Requirements are met • Low Overhead Frame formats • 100Mbps Goodput Achieved when • 20MHz and 2 transmit antennas • > 144Mbps Average PHY data rate • Rate Adaptation Patrik Eriksson et. al., WaveBreaker AB

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