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PHY/MAC Complete Proposal to TGad

PHY/MAC Complete Proposal to TGad. Date: 2010-05-02. Proposal overview. This presentation is part and in support of the complete proposal described in 802.11-10/432r0 (slides) and 802.11-10/433r0 (text) that: Supports data transmission rates up to 7 Gbps

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PHY/MAC Complete Proposal to TGad

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  1. PHY/MAC Complete Proposal to TGad Date: 2010-05-02 Carlos Cordeiro, Intel, et. al.

  2. Carlos Cordeiro, Intel, et. al.

  3. Carlos Cordeiro, Intel, et. al.

  4. Carlos Cordeiro, Intel, et. al.

  5. Proposal overview • This presentation is part and in support of the complete proposal described in 802.11-10/432r0 (slides) and 802.11-10/433r0 (text) that: • Supports data transmission rates up to 7 Gbps • Supplements and extends the 802.11 MAC and is backward compatible with the IEEE 802.11 standard • Enables both the low power and the high performance devices, guaranteeing interoperability and communication at gigabit rates • Supports beamforming, enabling robust communication at distances beyond 10 meters • Supports GCMP security and advanced power management • Supports coexistence with other 60GHz systems • Supports fast session transfer among 2.4GHz, 5GHz and 60GHz Carlos Cordeiro, Intel, et. al.

  6. Proposal presentation plan This presentation Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  7. Additional proposal supporting documents • To meet the TGad PAR, FRD, EVM and selection procedure requirements, the following additional supporting documents complement this proposal • Therefore, this proposal meets all the requirements in the TGad selection procedure to be classified as a complete proposal Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  8. Notable amendments to IEEE 802.11 Slide 8 Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  9. MAC/PHY proposal overview • Provides an unified and interoperable MAC/PHY across all mmWave implementations • Scalable across different usages, devices, and platforms • Adjustable to meet different power vs. performance trade-offs Protocol architecture 2.4/5GHz 60GHz Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  10. MAC Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  11. MAC challenges • As discussed in 802.11-09/572r0, the primary challenge for the MAC is how to deal with directional communication, which is used to combat the high propagation loss in 60GHz • Device discovery becomes a non-trivial problem • Devices need to find the direction for communication, which necessitates the support for beamforming (802.11-09/1153r2) • 802.11 DCF has limitations in the presence of directionality • How to exploit spatial frequency reuse in face of directional communication (802.11-09/782r0) Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  12. New MAC features(described in detail in separate presentations) • A new network architecture named Personal Basic Service Set (PBSS), while retaining the existent 802.11 network architectures • Channel access that support directionality and spatial frequency reuse, including both random access and scheduled access • A unified and flexible beamforming scheme that can be tuned to simple, low power devices as well as complex devices • Enhanced security (GCMP), link adaptation and power saving • Multi-band support (fast session transfer) Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  13. The Personal BSS (PBSS) • New network architecture in addition to infrastructure BSS and IBSS, which are also supported • PBSS is defined to address some unique usages and challenges of 60GHz communication • Usages: Rapid sync-n-go file transfer, projection to TV/projector, etc. • Challenges: directional channel access, power saving, etc. • More details in 802.11-09/391r0 • Ad hoc network similar to the IBSS, but: • A STA assumes the role of the PBSS Central Point (PCP) • Only the PCP transmits beacon frames Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  14. The Beacon Interval (BI) structure • Beacon time (BT): An access period during which one or more mmWave Beacon frames is transmitted • Association beamforming training (A-BFT): An access period during which beamforming training is performed with a PCP or AP • Announcement time (AT): A request-response based management access period during which a PCP or AP delivers non-MSDUs and provides access opportunities for STAs to return non-MSDUs • Data transfer time (DTT): An access period during which frame exchanges are performed between STAs. The DTT is comprised of contention-based periods (CBPs) and service periods (SPs) Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  15. Channel access • Channel access is coordinated using a schedule, which is delivered by the PCP/AP to non-PCP/non-AP STAs • STAs are permitted to transmit data frames during contention-based periods (CBPs) and service periods (SPs) • Access during CBPs is based on EDCA fine-tuned for directionalaccess • Access during SPs is reserved to specific STAs as announced in the schedule or granted by the PCP/AP Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  16. Fast session transfer (FST) support through multi-band operation • Enables transition of communication of STAs from any band/channel to any other band/channel in which 802.11 is allowed to operate • Supports both simultaneous and non-simultaneous operation • Supports both transparent and non-transparent FST • In transparent FST, a STA uses the MAC same address in both bands/channels involved in the FST • In non-transparent FST, the MAC addresses are different • Several improvements to speed-up the FST switching time such as transparent FST, security key establishment prior to FST, TS operation over multiple bands, and Block Ack operation over multiple bands Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  17. Beamforming (BF) • A unified and flexible BF protocol is proposed that can be tuned to simple, low power devices as well as complex devices • Same protocol is used for PCP/AP-to-STA beamforming and STA-to-STA beamforming • BF comprised of two independent phases: sector level sweep(SLS)phase and beam refinement protocol (BRP) phase • SLS: enables communication at the control PHY rate (MCS0), and typically only provides transmit training • BRP: enables receiver training and iterative refinement of the AWV of both transmitter and receiver • Support for beam tracking during data communication Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  18. BF training examples • Two phased arrays • Two transmit sector sweeps followed by a beam refinement • During a transmit sector sweep, the receiver may be using a quasi-omni receive pattern • Initiator has a phased array, responder has a single antenna • During the receive sector sweep, the responder transmit a sector sweep many times from its single antenna. The initiator switches receive pattern every packet. Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  19. Coexistence with other 60GHz systems • Proposal enables fair sharing of resources with 15.3c • The same channelization as other 60GHz systems is used, and the same SC chip rate as that of 15.3c CMS is adopted • As required in the TGad EVM (802.11-09/296r16), an AP should not start a BSS where the signal level is above a threshold or upon detecting a 15.3c CMS preamble at >= -60 dBm • In 802.11a/n, MCS 0 (BPSK, R=1/2) receive sensitivity is -82dBm and non-802.11 detection level is -62 dBm → 20 dB difference • In 60GHz, SC MCS 1 receive sensitivity is -68 dBm → 8 dB difference with respect to required 802.15.3c CMS preamble detection threshold • Requirement of detection of 802.15.3c CMS preamble is 12dB more stringent than 802.11a/n and non-802.11 detection! • STAs can perform channel measurements and report results to AP/PCP • Several mechanisms can be used to mitigate interference with other 60GHz systems, including: • Change operating channel, beamforming, reduce transmit power, move the BT (and thus the BI) in case of an AP or PCP, change or request the change of scheduled SPs and CBPs in the BI, defer transmission for a later time Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  20. PHY Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  21. Agenda • Channelization • PHY Overview • PHY general parameters • Common Preamble Preview • Golay sequences • Preamble structure • Short preamble • CEF • Coding scheme-LDPC • Single Carrier modulation • Control MCS • Single carrier MCS set • Single carrier low power mode • OFDM modulation • RF General parameters Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  22. Channelization Same channelization as 15.3c, compatible Mask Requirement for coexistence Channel separation 2160MHz Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  23. PHY Overview • Unified and interoperable PHY • Common preamble • Common MCS • Common coding • Different MCS sets for different usages: OFDM and SC • OFDM MCSs for high performance on frequency selective channels up to 64 QAM • SC modulation for low power/low complexity transceivers • SC MCS for control signaling (Channel, SNR durability) • SC Low Power MCS set • Simpler coding and shorter symbol structure to enable low power implementation • Embedded support in BF • Different presentation (802.11-10/0430r0, 802.11-10/0450r0) Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  24. PHY Parameters Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  25. PHY General parameters • Sampling rate • SC PHY MCS set Symbol Rate = 1760MHz • OFDM MCS set Sampling Rate = 2640 MHz • Sampling Rate is Exactly 1.5x the SC symbol rate • SC block – 512 symbols of which 64 chips GI • OFDM nominal sample rate 2640MHz = 1.5 times SC symbol rate • 512 samples FFT • 128 samples GI • 336 data subcarriers • 16 pilot subcarriers • Common Packet Structure Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  26. Common Preambles Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  27. Complementary sequences H a*h Golay Correlator Ra=a*a*h a ∑ • Time domain channel estimation Rb=b*b*h b*h H Golay Correlator b + + + - - - Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  28. Short Preambles • Complementary sequences are used to differentiate control MCS and high rate MCSs. • 38 repetition for CP • 15 repetition for SC/OFDM STF=38xGb128, -Gb, -Ga CEF CP: -Gb128 -Ga128 Gb128 Gb128 -Gb128 … STF=15xGa128,-Ga CEF High rate: -Ga128 Ga128 Ga128 -Gb128 … Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  29. Common Preamble • Transmitted using π/2-BPSK at SC symbol rate • Short Training field composed of 15 repetitions of a 128 samples Golay sequence • Channel Estimation based on 512 points complementary sequences followed by a guard interval Slide 29 Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  30. SC/OFDM Channel Estimation Sequence • The use of SC/OFDM MCS set is signaled using the CEF pattern as shown below STF CEF SC: Ga128 -Ga128 -Ga128 -Gb128 -Gb128 -Ga128 Gb128 -Ga128 -Gb128 Ga128 -Gb128 … v128 u512 v512 OFDM: STF CEF Ga128 -Ga128 -Ga128 -Gb128 -Gb128 Ga128 -Gb128 -Gb128 -Ga128 Gb128 -Ga128 … v128 v512 u512 Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  31. LDPC Coding Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  32. LDPC Code Set Overview • Four codes of common codeword length of 672 • Cyclic shifted identity (CSI) construction • Submatrix size 42 • Excellent coding gain on realistic channels • Construction supports high throughput implementation • Single construction supports code rates of 1/2, 5/8, 3/4, and 13/16 Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  33. LDPC Code Set Implementation • Low complexity / low latency encoding • Shared terms in systematic product calculation across all codes • Back substitution for parity calculation • High throughput / low power decoding • Layer decoding • Each code matrix H has 4 layers with a single set element per column • 4 clock cycles per decoder iteration • Fully parallel belief propagation decoding • Code set super-position matrix has single CSI value per location which minimizes decoder multiplexing and routing • 1 clock cycle per decoder iteration Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  34. LDPC Matrices Slide 34 Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  35. LDPC Code Set Performance on AWGN Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  36. LDPC Code Set Performance • OFDM with QPSK modulation on 3ns Exp Decaying PDP Channel • 20 iterations floating point belief propagation decoding Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  37. SC MCS 0: Control MCS Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  38. Control MCS • Very low SNR modem to allow pre-beamforming link • Control MCS based on SC modulation ~27.5 Mbps • π/2 32 Golay spreading sequence • Differential encoding • Short rate 1/2 LDPC code using the existing rate 3/4 LDPC code • Effective shorter block size-336 bits • Spreading mitigates long channels • Differential encoding allows shorter preambles, and results in a robust modem in the presence of phase noise • Short LDPC code is efficient for short packets • Bits are evenly divided between codewords to allow equal protection • A-MPDU aggregation is not allowed using Control MCS • Maximum length is limited to 1024 bytes Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  39. Control MCS Performance • Simulation Conditions: • Packet Length-256 Bytes • AWGN • No impairments Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  40. Single Carrier MCS Set Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  41. SC Modulation • 448 chips per symbol • 64 chips constant GI • Tracking purposes • Can be used for equalization • Pi/2 rotation applied to all modulations • To reduce PAPR for BPSK • To enable GMSK equivalent modulation Mandatory Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  42. SCM Performance-AWGN • Simulation Conditions: • Packet Length-8192 Bytes • AWGN • Red line-With impairments (PN, PA) • Blue line-no impairments BPSK MCSs 16QAM MCSs QPSK MCSs Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  43. SC Low Power MCS set Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  44. Low Power SC Mode Motivation • Targets: • Peak power for the entire solution including PHY, MAC, Memory, RF, IOs, peripheral < 500 mW (e.g., USB 2.0) • Average power of PHY/MAC < 150 mW • Maximum delay spread for a 2 m range is in the order of 5 ns • Therefore, there is a need for a low complexity low power mode that satisfies these requirements: • Simple FEC: • Reed Solomon (224,208) for high data rate • Outer Reed Solomon (224,208) + Inner Hamming like block code(16,8) for medium data rate • Simple Equalizer for very short multipath Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  45. SC Low Power MCS set • The FEC is one of the major contributor to the relatively high power consumption of the current SC mode • Simple FEC: • Reed Solomon (224, 208) for high data rate • Outer Reed Solomon (224, 208) + Inner Hamming like block code (16,8) for medium data rate Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  46. Low Power Mode Blocking Ga64 d448 Current SC • Compatible and built upon current SC mode • Block size is 64 chips • Sampling rate of 1.76GHz Block 1 Block 2 Block 7 ... Ga64 d56 G8 d56 G8 LP MCS set Block 1 Block 2 Block 3 Block 7 ... ... ... Ga64 d56 G8 d56 G8 d56 G8 Block-512 Block-512 Block-512 Ga64 ~ 218.18 ns ~ 1.745 μs Preamble Header Data STF Ga128 x 15;-Ga SC CEF ~ 1.091 μs ~ 0.655 μs Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  47. Low Power MCS Performance • Simulation Conditions: • Packet Length-4096 Bytes • AWGN-Upper Figure • 1ns RMS Delay Spread-Lower Figure • No impairments Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  48. OFDM MCS set Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  49. OFDM Modulation • 512 points FFT • GI length of 128 • Symbol interleaver for 16 QAM and 64 QAM • 16 QAM – 2 code words per symbol • 64 QAM – 3 code words per symbol Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

  50. OFDM Modulation • SQPSK-Spread QPSK • QPSK Modulation (DCM) • DTP (Dynamic tone pairing) • Via feedback from the receiver to the transmitter • Number of tone per group, index • Pilots • Positions: 20 carriers spacing -150:20:150 • LFSR switched per symbol Carlos Cordeiro, Intel /Gal Basson, Wilocity/et. al.

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