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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: TG4a UWB-PHY overview. Date Submitted: November 30, 2005 Source: Gian Mario Maggio (STMicroelectronics) Contact: Gian Mario Maggio

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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: TG4a UWB-PHY overview. Date Submitted: November 30, 2005 Source: Gian Mario Maggio (STMicroelectronics) Contact: Gian Mario Maggio Voice: +41-22-929-6917, E-Mail: gian-mario.maggio@st.com Abstract: Review of the 802.15.4a UWB-PHY. Purpose: To provide a summary of the current status of the 802.15.4a UWB-PHY and an outlook of the future TG4a work for this portion of the standard. 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. Gian Mario Maggio (ST)

  2. 802.15.4a UWB-PHY (http://www.ieee802.org/15/pub/TG4a.html) Gian Mario Maggio STMicroelectronics November 30th, 2005 Gian Mario Maggio (ST)

  3. Outline • IEEE 802.15.4a • UWB-PHY • Band-plan • Data rates • Preamble • Modulation • Spreading • Coding • Waveforms Gian Mario Maggio (ST)

  4. 802.15.4a Overview Gian Mario Maggio (ST)

  5. 802.15.4a: Introduction • The IEEE 802.15 Low Rate Alternative PHY Task Group (TG4a) for Wireless Personal Area Networks (WPANs) has defined a project for an amendment to 802.15.4 for an alternative PHY • The main interest is in providing communications and high-precision ranging/localization capability (1 meter accuracy), high aggregate throughput; as well as adding scalability to data rates, longer range, and lower power consumption and cost • These additional capabilities over the existing 802.15.4 standard are expected to enable significant new applications and market opportunities Gian Mario Maggio (ST)

  6. 802.15.4a: Short History • 802.15.4a became an official TG in March 2004 (committee work tracing back to November 2002) • The committee is actively drafting an alternate PHY specification for the applications identified • In March 2005, the baseline specification was selected (without enacting down-selection procedures)  baseline with 100% approval • The baseline is two optional PHYs consisting of: • UWB Impulse Radio (operating in unlicensed UWB spectrum) • Chirp Spread Spectrum (operating in unlicensed 2.4GHz spectrum) • The UWB Impulse Radio will be able to deliver communications and high precision ranging Gian Mario Maggio (ST)

  7. 802.15.4a: Schedule Gian Mario Maggio (ST)

  8. TG4a Working Groups UWB-PHY (P. Rouzet – ST)  P. Orlik (MERL)/I. Lakkis (Novowave) CSS-PHY (J. Lampe – Nanotron) Sub-GHz (P. Houghton – AetherWire) Ranging (V. Brethour – Time Domain) Channel Modeling (A. Molisch – MERL) MAC (J. Bain – Fearn Consulting ) Gian Mario Maggio (ST)

  9. UWB-PHY Sub-groups Bandplan TSE: Saeid Safavi Pulse modulation TSE: Phil Orlik Pulse compression TSE: Ismail Lakkis Simulation TSE: Matt Wellborn Sub-GHz UWB-PHY TSE: Mark Jamtgaard Liaison to IEEE 802.19 Patricia Martigne Gian Mario Maggio (ST)

  10. UWB-PHY: Introduction • Impulse-radio based (pulse-shape independent) • Support for different receiver architectures (coherent/non-coherent) • Flexible modulation format • Support for multiple rates • Support for SOP (simultaneously operating piconets) Gian Mario Maggio (ST)

  11. Operating Frequency Range(Band-Plan) Gian Mario Maggio (ST)

  12. Band-Plan • The UWB-PHY operates in the frequency range from 3211–4693 MHz (LFB) and, optionally, from 5931.9-10304.25 MHz (HFB) • LFB: A compliant device shall be capable of transmitting in the mandatory channel #2 (*) with a 3dB-bandwidth of 494MHz • HFB: Transmission in all other frequency band is optional • If transmission in HFB is desired then a transmitter shall be capable of transmitting in channel #8 (*) (*) See next slide for channels assignment Gian Mario Maggio (ST)

  13. Channels Assignment Gian Mario Maggio (ST)

  14. 4 111 MHz 207 MHz 2 1 2 3 fGHz 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 LFB Band-Plan Gian Mario Maggio (ST)

  15. 13 14 15 4 4 4 -41.3 5 6 7 8 9 10 11 12 PSD dBm/MHz -70 fGHz 6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75 9.00 9.25 9.50 9.75 10.00 10.25 10.50 10.75 HFB Band-Plan Gian Mario Maggio (ST)

  16. Oscillator Reference Divider ÷ R Phase Detector LPF VCO fcomp fc fX ÷ N ÷ M fs = 494 MHz LFB: PLL Reference Diagram XTAL Gian Mario Maggio (ST)

  17. Oscillator Reference Divider ÷ R Phase Detector LPF VCO fcomp fX fc, high band XTAL ÷ N ÷ 2 fs = 1352 MHz via ÷ 3 ÷ M fs = 507 MHz HFB: PLL Reference Diagram fc, low band Gian Mario Maggio (ST)

  18. 507MHz 15.84375MHz 7.921875MHz 253.5MHz ÷ 2 ÷ 16 ÷ 2 HFB: Remarks • Use of the “free spectrums” of both Japan and EU (OFCOM) • Integer product relationship between center frequencies and PRF • Harmonization with the accepted low frequency band plan (Use of the same PRF) • A single PLL can generate all necessary frequencies using direct synthesis • The supported PRFs range from 507 MHz to 3.9609375 MHz through simple division by a power of 2: Gian Mario Maggio (ST)

  19. Data Rates Gian Mario Maggio (ST)

  20. Data Rates Gian Mario Maggio (ST)

  21. Optional: ~100 kb/s Data Rate Gian Mario Maggio (ST)

  22. Ranging/Acquisition Preamble Gian Mario Maggio (ST)

  23. Preamble Symbol • The preamble field is used by the transceiver for: • Acquisition: to obtain chip and symbol synchronization with an incoming message • Ranging: to acquire/track signal leading edge Gian Mario Maggio (ST)

  24. Preamble Length • The adopted preamble lengths (symbols) are 64, 256, 1024, 4096: + Optional (short) length-16 preamble for improved energy efficiency in high data-rate communications Gian Mario Maggio (ST)

  25. Preamble Codes: Length-31 • PBTS (Perfect Balanced Ternary Sequences) are adopted as ranging/acquisition codes, Si • The code can be selected from length-31 or length-127 PTBS • Length-31 ternary codes: • Note: These are the six codes with the best cross-correlation of the 12 possible codes with perfect periodic auto-correlation Gian Mario Maggio (ST)

  26. Preamble Codes: Length-127 • Length-127 ternary codes: • Note: These are the 26 codes with perfect periodic autocorrelation and best cross-correlation properties Gian Mario Maggio (ST)

  27. Auto-correlation & Cross-correlation (L = 31) Gian Mario Maggio (ST)

  28. Preamble Structure Preamble Header Payload • Two forms of preamble are supported: • Normal preamble • Preamble for ~100 kb/s • SYNC: Synchronization Field • SFD: Start Frame Delimiter Field • CE: Channel Estimation Field SYNC/CE SYNC SFD Si Si Si Si Si Si -Si 0 - Si 0 -Si 0 -Si 0 (a) or Si Si Si Si Si Si -Si -Si 0 0 -Si -Si 0 0 (b) Gian Mario Maggio (ST)

  29. Preamble Parameters (L=31) Gian Mario Maggio (ST)

  30. Preamble Parameters (L=127) Gian Mario Maggio (ST)

  31. Definitions Gian Mario Maggio (ST)

  32. PRF Definition Pulse Repetition Interval 1 2 3 4 5 6 7 8 N-1 N ………………………… Non-inverted pulses are blue, Inverted pulses are green. Pulse Width, Tc ~ 4ns @ 500MHz BW ………………………................. …………… Quiet time Active time Symbol Interval Gian Mario Maggio (ST)

  33. Pulse Repetition Frequency Gian Mario Maggio (ST)

  34. Minimum PRF Requirements Gian Mario Maggio (ST)

  35. Data Preamble Peak Preamble PRF = ~ 31 MHz (actually 494/16) Peak Preamble PRF = 494 MHz PRF: Preamble & Data Harmonization Average Preamble PRF ~ 16 MHz (actually 494/31)  every 1uS, 16 pulses Average Data PRF ~ 16 MHz 1uS 16 pulses  This maintains same pulse amplitude for Preamble and Data! Gian Mario Maggio (ST)

  36. Modulation Gian Mario Maggio (ST)

  37. Baseline Modulation • Simple, scalable modulation format • One mandatory mode plus one or more optional modulation modes • Modulation compatible with multiple coherent/non-coherent receiver schemes  Flexibility for system designer • Time hopping (TH) to achieve multiple access Gian Mario Maggio (ST)

  38. Modulation Format • The UWB-PHY is required to support both coherent and non-coherent receivers • The modulation format is a combination of Pulse Position Modulation (PPM) and Binary Phase Shift Keying (BPSK) • A UWB PHY symbol is capable of carrying two bits of information: one bit is used to determine the position of a burst of pulses while an additional bit is used to modulate the phase (polarity) of this same burst Gian Mario Maggio (ST)

  39. Chip Rate • The UWB-PHY uses an IR-based signaling scheme in which each information-bearing symbol is represented by a sequence/burst of short time duration pluses • The duration of an individual pulse is nominally considered to be the length of a chip • Chip duration is equal to 2.02429 ns or a chipping rate of 494MHz Gian Mario Maggio (ST)

  40. 47 47 47 47 48 48 48 48 0 0 0 0 1 1 1 1 31 31 31 31 32 32 32 32 33 33 33 33 63 63 63 63 15 15 15 15 16 16 16 16 burst PPI symbol duration Modulation PPM bit (seen by coherent and non coherent receiver) BPSK bit (seen by coherent receiver only) S -S S -S Gian Mario Maggio (ST)

  41. S = +--+-++- = S 1 chip ~ 2 ns burst duration symbol duration Symbol Structure Gian Mario Maggio (ST)

  42. Reference Modulator Note: “Input Data” is after FEC coding Gian Mario Maggio (ST)

  43. Receiver Architecture Gian Mario Maggio (ST)

  44. Modulation Parameters • Mandatory data rate: • Optional data rates @PRF=15.94 MHz • Optional data rates @PRF=3.98 MHz Gian Mario Maggio (ST)

  45. Spreading Gian Mario Maggio (ST)

  46. Spreading • In addition to the data modulation, the UWB-PHY symbol provides for some multi-user access interference rejection in the form of TH • Each symbol contains a single burst of pulses and the burst length is typically much shorter than the duration of the symbol • The location of the pulse within each burst can be varied on a symbol-to-symbol basis according to a TH code • This is part of the functionality provided by the “Scrambler and Burst Position Hopping” Gian Mario Maggio (ST)

  47. Scrambling • The constituent pulses in each burst are scrambled by applying a time varying scrambling sequence • This scrambler is a pseudo-random binary sequence (PRBS) defined by a polynomial generator. • The polynomial generator, g(D), for the pseudo-random binary sequence (PRBS) generator is g(D) = 1 + D14 + D15, where D is a single bit delay element. • The polynomial not only forms a maximal length sequence, but is also a primitive polynomial. Using this generator polynomial, the corresponding PRBS, sj, is generated as where “” denotes modulo-2 addition Gian Mario Maggio (ST)

  48. Scrambler • Scrambler linear feedback shift register: Gian Mario Maggio (ST)

  49. Time Hopping • The hopping sequence is derived from the same linear feedback shift registers by using the output of the first three registers • When each symbol, x(k)(t), is generated, the spreader is run for Nburst cycles  the Nburstconsecutive outputs of the spreader are the spreading sequence for the symbol (sj, j = 1,2, …, Nburst) • The current hopping position, h(k) is determined by the following equation: • The state variables are sampled at the start of the transmission of the current modulation symbol Gian Mario Maggio (ST)

  50. S S S S 47 47 47 47 48 48 48 48 0 0 0 0 1 1 1 1 31 31 31 31 32 32 32 32 33 33 33 33 63 63 63 63 15 15 15 15 16 16 16 16 -S -S -S -S S S S -S -S -S Spreading possible positions obtained through scrambling Guard time for channel delay spread (260ns) S -S S -S Note: S value is also changed at each symbol Gian Mario Maggio (ST)

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