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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [STMicroelectronics proposal for IEEE 802.15.3a Alt PHY ] Date Submitted: [14 July, 2003] Source: [ Didier Helal (Primary) Philippe Rouzet (Secondary) ] Company [ STMicroelectronics ]

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [STMicroelectronics proposal for IEEE 802.15.3a Alt PHY] Date Submitted: [14 July, 2003] Source: [Didier Helal (Primary) Philippe Rouzet (Secondary)] Company [STMicroelectronics] Address [STMicroelectronics, 39 Chemin du Champ des Filles 1228 Geneve Plan-les-Ouates, Switzerland] Voice [+41 22 929 58 72 or +41 22 929 58 66 ], Fax [+41 22 929 29 70], E-Mail :[didier.helal@st.com,philippe rouzet@st.com] Re: [This is a response to IEEE P802.15 Alternate PHY Call For Proposals dated 17 January 2003 under number IEEE P802.15-02/372r8 ] Abstract: [This document contents the proposal submitted by ST for an IEEE P802.15 Alternate PHY based on UWB technique.] Purpose: [Presentation to be made during July IEEE TG3a session in San Francisco, California] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Didier Helal and Philippe Rouzet, STM

  2. STMicroelectronics Proposal forIEEE 802.15.3a Alternate PHY July 2003, San Francisco, California Didier Hélal, Philippe Rouzet R. Cattenoz, C. Cattaneo, L. Rouault, N. Rinaldi, L. Blazevic, C. Devaucelle, L. Smaïni, S. Chaillou Didier Helal and Philippe Rouzet, STM

  3. Contents • Introduction to Pulse Position Modulation • UWB PHY Proposal • Performances results Didier Helal and Philippe Rouzet, STM

  4. Pulse Position Modulation (1) PRF = Pulse Repetition Frequency Time A system with a PRF of 250MHz transmits 250 million pulses per second PRP = Pulse Repetition Period = 1/PRF Time A system with a PRF of 250MHz transmits one pulse every 4 nanosecond Didier Helal and Philippe Rouzet, STM

  5. Position 1 Position 2 Position 3 Position 4 A system with a PRF of 250MHz using a 4-PPM + Polarity transmits 750 million bits per second Time Pulse Position Modulation (2) A system with a PRF of 250MHz using a 4-PPM transmits 500 million bits per second Time Didier Helal and Philippe Rouzet, STM

  6. 1 bit / pulse Polarity 2-PPM + Polarity 2 bits / pulse 4-PPM + Polarity 3 bits / pulse Equally spaced Positions 1 2 3 4 t Tp = 300ps Didier Helal and Philippe Rouzet, STM

  7. 011 010 001 000 111 110 100 101 BIT MAPPING • Gray-invert mapping: takes advantage from the bi-orthogonal modulation PPM+Polarity. Didier Helal and Philippe Rouzet, STM

  8. MODULATION Didier Helal and Philippe Rouzet, STM

  9. PPM Modulation capacity • Increasing the number of pulse positions brings better efficiency Didier Helal and Philippe Rouzet, STM

  10. Channel coding options (1) • Convolutional code • Code rate ½, constraint length K=7, [133,171]: • Puncture table for code rate = 2/3: [1 1 0 1 1 1 1 0] Didier Helal and Philippe Rouzet, STM

  11. Channel coding options (2) • Turbo codes PCCC (Parallel Concatenation of Convolutional Codes) • Code rate 1/3. With puncturing:1/2, 2/3,7/8. • RSC (recursive systematic convolutional) 13,15(octal def.). • Block size: 512. • Low latency : 5 s Didier Helal and Philippe Rouzet, STM

  12. Adaptive band Pulse shape • Pulse shape should be adapted to any regulation, provided the pulse power spectral density fits emission mask. • Flexibility on pulse shape enables compatibility with more stringent regulations worldwide. • See ref. IEEE 802.15-03/211r0. Didier Helal and Philippe Rouzet, STM

  13. 5 6 7 8 9 10 4 Backward and Forward compatibility • First generation systems will use the lower part of the band due to technology limitations, e.g. 3-7GHz • Next generation will extend this bandwidth e.g. to 3-10GHz, older systems using the energy in 3-7GHz band. UNII Frequency (GHz) 11 3 Didier Helal and Philippe Rouzet, STM

  14. Example of a full band pulse shape Average TX power = 0.3 mW Peak emission power in 50MHz = -10 dBm BW-10dB = 7.26 GHz Didier Helal and Philippe Rouzet, STM

  15. Example of a low band pulse shape Average TX power = TBD mW Peak emission power in 50MHz = TBD dBm BW-10dB = 4 GHz Didier Helal and Philippe Rouzet, STM

  16. FRAME:Known Training Sequencefor Frame Synchronization and Channel Estimation Frame Example of a simplified emitted pulse train Pulse shape not shown (use rectangle for clarity) Preamble Modulated user data Frame Preamble PRP Time Hopping +Polarity 2-PPM +Polarity (Time Hopping optional) Didier Helal and Philippe Rouzet, STM

  17. BEACON is a regular frame with appended preamble for Coarse Synchronization Beacon Beacon Preamble Frame Sync.+ Ch. Est Piconet Information Coarse Sync. PRP Time Hopping +Polarity Time Hopping +Polarity 2-PPM +Polarity (Time Hopping optional) Didier Helal and Philippe Rouzet, STM

  18. Cell synchronization (1) • A device which enters the piconet has to • Detect the piconet code • Find approximate beginning of beacon data • Estimate its clock drift with PNC • Channel estimation and fine synchronization to allow best energy capture • Compensate for residual clock drift Scenario Cell synch Cell synch Dev-dev synch Didier Helal and Philippe Rouzet, STM

  19. Cell synchronization (2) • Coarse synchronization 1.1 Detection of the piconet code among 20 possible. 1.2 Alignment: find the end of the superframe beacon preamble. Goal is also to find the beginning of the channel impulse response. This is done by detecting the first path above a fixed threshold. May lead to some uncertainties (thus operation is called ‘coarse’). • Coarse clock drift correction, based on information given in 1.2. Is made based on several superframe beacon preambles. Use of basic interpolation or adaptive filtering (like Kalman, should the oscillator spec require it) to predict clock drift. • Fine synchronization: can take place now, with better accuracy, since some of the clock drift between PNC and DEV has been removed in 2. Via channel estimation and processing, can align to the beginning of the channel impulse response with much more accuracy than after 1.2. • Fine clock drift correction, based on information given in 3. Didier Helal and Philippe Rouzet, STM

  20. i = 1,2,…,78: sequence number • n = 0,1,…,78: TH offset index Coarse Synchronization (1) Preamble coding : TIME HOPPING + POLARITY Preamble codes : Sequences of length Lc = 79 TH = Quadratic-Congruence (QC) sequences Cn = time-hopping offset (multiple of time-hopping resolution) POL = Derived from row of a Hadamard matrix of size 80 x 80 Didier Helal and Philippe Rouzet, STM

  21. One sequence: LC*PRP End of Beacon Preamble (EOBP) signature ….. + + + - - 120 repetitions Beacon preamble duration: DC = 77.7 s Coarse Synchronisation (2) • Preamble construction • PRP = 8 ns. TH offset resolution: 50ps. • Sequence is repeated R = 120 + 3 times. • Duration of coarse sync beacon preamble: DC = R*LC *PRP = 77.7 s. Didier Helal and Philippe Rouzet, STM

  22. Coarse Synchronisation (3) Superframe N Superframe N+1 Contention Free Period Beacon Contention Access Period MCTA 1 preamble CTA m header body CTA 2 CTA x preamble MCTA n CTA 1 preamble … … … … • Detection : Find one sequence among 20 • Alignement : Find end of coarse synchronization beacon preamble with a precision of ~10 ns. Didier Helal and Philippe Rouzet, STM

  23. Coarse Clock Synchronization (1) Superframe N Superframe N+1 Contention Free Period Beacon Contention Access Period MCTA 1 preamble CTA m header body … CTA 2 CTA x preamble preamble preamble MCTA n CTA 1 … … … ti ti+1 • correct clock drift between TX DEV and RX DEV TSF: average superframe period (e.g. 10 ms) slope of clock drift = ((ti+1 – ti) – TSF)/TSF Didier Helal and Philippe Rouzet, STM

  24. Coarse Clock Synchronization (2) Coarse Drift estimation and tracking • Clock tracking algorithm uses coarse synchronization ouptuts to predict clock drift over next superframe, by basic interpolation or implementing an adaptive filter (like Kalman, should the oscillator spec require it). • Drift correction down to ~1 ppm. Enough for fine synchronization & channel estimation, done over 6 s. Didier Helal and Philippe Rouzet, STM

  25. Fine Synchronization Superframe N Superframe N+1 Contention Free Period Beacon Contention Access Period MCTA 1 preamble CTA m header body CTA 2 CTA x preamble MCTA n CTA 1 preamble … … … … DEV-A demodulates beacon Fine Synchronisation is made jointly with channel estimation and optimizes energy capture DEV-A synchronized to PNC’s clock Fine synchronization algorithm gives end of beacon preamble (blue) with good accuracy Didier Helal and Philippe Rouzet, STM

  26. Fine Clock Synchronization Fine clock drift estimation and tracking • Clock tracking algorithm uses fine synchronization ouptuts to refine clock drift prediction down to 0.1ppm. Enough for demodulation over 100 s Superframe N Superframe N+1 Contention Free Period Beacon Contention Access Period MCTA 1 preamble CTA m header body … CTA 2 CTA x preamble preamble preamble MCTA n CTA 1 … … … Didier Helal and Philippe Rouzet, STM

  27. Frame sent to DEV-A by DEV-B Preamble Body Header DEV-to-DEV Synchronization (1) Superframe N Superframe N+1 Contention Free Period Beacon Contention Access Period MCTA 1 preamble CTA m header body CTA 2 CTA x preamble MCTA n CTA 1 preamble … … … … • Clock drift is known and can be corrected • Fine Synchronisation and channel estimation • Demodulation DEV-A’s clock is synchronized to DEV-B’s clock, and can start to demodulate the data contained in the frame sent by DEV-B. DEV-A wakes up, and needs to synchronize to DEV-B’s clock. Didier Helal and Philippe Rouzet, STM

  28. DEV-to-DEV Synchronization (2) PNC f1 f2 DEV-1 TX f12 DEV-2 RX • f1 and f2 are estimated during cell synchronization phase, by DEV-1 and DEV-2 respectively • f12 is known by PNC and must be corrected by DEVs Didier Helal and Philippe Rouzet, STM

  29. DEV-to-DEV Synchronization (2) Two solutions • RX DEV corrects for both f1 and f2. + Better precision - MAC needs to provide f values to all piconet devices. • TX DEV correct f1 by adjusting pulse position transmission +RX DEV does not need to know f1 - Less precise Didier Helal and Philippe Rouzet, STM

  30. PHY-SAP Data Throughput close to Payload Bit Rate Optimized Packet Overhead Times PHY Header, MAC Header (802.15.3 format), HCS use 62.5Mb/s mode Didier Helal and Philippe Rouzet, STM

  31. MAC enhancements Proposed MAC is compliant with existing MAC IEEE 802.15.3 • Introduction of optional minor MAC adaptations to optimize • Receiver power consumption • Complexity (synchronization) • Performance (ARQ) Didier Helal and Philippe Rouzet, STM

  32. Frame reception (1) • Approximate frames Times Of Arrival (TOAs) used in CTA slots TOA information announced by source DEV at the begining of CTA • Used for channel estimation & synchronization • Several ways of TOA signaling possible (i.e. one example presented after) • Benefits : • ARQ scheme can be improved (One ACK per CTA to lower overhead) Didier Helal and Philippe Rouzet, STM

  33. MIFS MIFS MIFS MIFS MIFS Frame 4 Frame 5 3 6 MIFS MIFS Frame 1 Frame 2 CTA slot in superframe TOA 4 TOA 3 TOA 2 TOA 5 TOA 1 TOA 2 TOA 3 TOA 4 TOA 5 TOA 6 CTA Header announcing TOAs TOA 1 TOA 6 Proposed TOA used by MAC for Frame synchronization • Use of approximate frame TOAs to manage different lengths of frames and facilitate frame synchronization Didier Helal and Philippe Rouzet, STM

  34. Frame reception (2) • Randomized access without CAP Use MCTA slots and Slotted Aloha instead of CAP VERY LOW POWER CONSUMPTION • Randomized access within CAP without CSMA/CA Use CAP with a new Slotted mechanism LOW POWER CONSUMPTION • Randomized access within CAP with CSMA/CA Use CAP as defined in 802.15.3: CSMA/CA with CCA Didier Helal and Philippe Rouzet, STM

  35. 20ns 20ns 20ns 20ns 20ns … 10μs 10μs 10μs 10μs Randomize access within CAP • CSMA/CA in CAP is possible by CCA through preamble detection but not efficient • CCA consumes a lot of energy (due to UWB environment, true for all PHY layer proposals and not only STM one) • Not suitable for time-bounded consumer applications (audio/video streaming) • Better solution is to do CCA by Slotted CAP mechanism CAP Didier Helal and Philippe Rouzet, STM

  36. Proposed Alternate PHY enablesSingle Chip FULL CMOS solution Through DIRECT SAMPLING on 1 BIT and DIGITAL MATCHED FILTERING Learn pulse signature after channel propagation Didier Helal and Philippe Rouzet, STM

  37. Demodulation is performed by Match-Filtering Demodulation Rx signal Match-filtering The match-filter is the estimate of the pulse signature through channel propagation No pulse shape is assumed by receiver ! Take advantage of multi-path (complete immunity) Tx signal Channel Estimation Average Compound Channel Response Channel+ Noise Didier Helal and Philippe Rouzet, STM

  38. Channel estimation chain 1 bit ADC • Picture shows E/No = 6dB • Time window is 50ns and 1ns Average of 750 pulses (1-bit sampled) Noise injection Didier Helal and Philippe Rouzet, STM

  39. Channel estimation • The channel estimated is compared with the actual channel response • Averaging 1 bit data remove noise and gets accurate estimation Didier Helal and Philippe Rouzet, STM

  40. Channel estimation easy to implement • Each point of the channel estimation can be seen as one finger of a rake receiver 64 ns = 1280 fingers of 50 ps width • Channel estimation consists in coherent integration of received pulses. One bit ADC makes the operation a simple increment/decrement No multiplication or complex operator ! • Estimated gate count of the whole channel estimation block bit slice number of gates * number of bit of the counter * number of channel point (20*7*1280 = 179200 gates) • Power consumption Parallel hardware implementation of all fingers Frequency of operations is low (1/PRP) Didier Helal and Philippe Rouzet, STM

  41. Optional Antenna Pulse Generator ABR BP Filter ABR TDD PTC Clock Synthesizer Switch 1-bit ADC LNA RF block UWB System-on-Chip Block Diagram TX Data Frag-mentation TX Preparation Channel Coding Modulation & coding TX Control PTC Channel estimation Synchronization RX Control Demodulation Channel Decoding Defrag- mentation RX Data MAC block (Bottom part) Baseband block PTC = Piconet Time Control ABR = Adaptive Band Rejection MAC+BB+RF on same silicon except BP filter and Antenna Didier Helal and Philippe Rouzet, STM

  42. ABR BP Filter ABR Link Budget Optional Antenna Noise figure for all RX chain referred at the antenna output Pulse Generator TDD Switch Clock Synthesizer 0.5dB loss 2dB loss G = 16dB 1-bit ADC LNA NF = 3dB 2dB NF = 9dB Clock Jitter : 10ps rms (maximum from 0.13m silicon measurements) Implementation loss = jitter effect <2dB(varies with pulse shape) + 2dB margin in order to enable simplest demodulation Didier Helal and Philippe Rouzet, STM

  43. Performances Summary • The following results are voluntary based on • 3-7GHz pulse instead of 3-10GHz • Convolutional coding instead of Turbo Coding Didier Helal and Philippe Rouzet, STM

  44. 110Mbps @ 10m, AWGN EFFECTIVE THROUGHPUT 125 Mbps MAXIMUM RANGE TBD m RESULTS INCLUDE SHADOWING Didier Helal and Philippe Rouzet, STM

  45. 200Mbps @ 4m, AWGN EFFECTIVE THROUGHPUT 250 Mbps MAXIMUM RANGE TBD m RESULTS INCLUDE SHADOWING Didier Helal and Philippe Rouzet, STM

  46. 480Mbps @ 1m , AWGN EFFECTIVE THROUGHPUT 500 Mbps MAXIMUM RANGE TBD m RESULTS INCLUDE SHADOWING Didier Helal and Philippe Rouzet, STM

  47. 55Mbps @ 10m, AWGN EFFECTIVE THROUGHPUT 62.5 Mbps MAXIMUM RANGE TBD m RESULTS INCLUDE SHADOWING Didier Helal and Philippe Rouzet, STM

  48. Coding Performances in CM4 channel For similar complexity Using a convolutionnal coding instead of a Turbo coding results in a 1.4dB loss in performances Didier Helal and Philippe Rouzet, STM

  49. Coexistence and regulatory impact • Coexistence with in-band systems ensured by TX pulse shaping or filtering • System is independent from pulse shape • Transmit power control reduces interferences • Helped by location awareness capability (distance can be estimated with 3cm resolution) • No impact on current regulation • FCC’s Part 15 rules followed • Additional spectrum protection can be supported • 802.15.3 Power Management modes are supported (DSPS, PSPS, APS) Didier Helal and Philippe Rouzet, STM

  50. Simultaneously operating Piconets Single Interferer Interferer dint CM1, CM2, CM3 or CM4 multipath channel CM1, CM2, CM3 or CM4 multipath channel TX DEV Rx level = (limit PER=8%) + 6dB dref RX DEV Modulation : 2-PPM, Prp = 8 ns, CR 1/2, 125 Mbps Continuous overlapping interferer transmission (worst condition) Didier Helal and Philippe Rouzet, STM

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