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

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Impulse Radio Signaling for Communication and Ranging] Date Submitted: [12 May 2005] Source: [Francois Chin, Lei Zhongding, Yuen-Sam Kwok, Xiaoming Peng] Company: [Institute for Infocomm Research, Singapore] Address: [21 Heng Mui Keng Terrace, Singapore 119613] Voice: [65-68745687] FAX: [65-67744990] E-Mail: [chinfrancois@i2r.a-star.edu.sg] Re: [] Abstract: [Presents signaling options to achieve precision ranging with both coherent and non-coherent receivers] Purpose: [To discuss which signal waveform would be the most feasible in terms of performance and implementation trade-offs] 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. Francois Chin (I2R)

2. Objectives • PRF definition • Impulse Radio Signaling Proposal • Common Signaling & Receiver-Specific Signaling for different receivers, for Synchronisation, Ranging and Data Communications • Deterministic Pulse structures • Receiver Code Sequences Francois Chin (I2R)

3. PRI VPeak TC PRF: Definition • Pulse repetition frequency (PRF): Number of pulses occurring in 1 s. • Pulse repetition interval (PRI): Time from the beginning of one pulse to the beginning of the next. Francois Chin (I2R)

4. PRF Definition : Example Pulse Repetition Interval 1 2 3 4 5 6 7 8 N-1 N ………………………… Non0inverted pulses are blue, Inverted pulses are green. Pulse Width, Tc ~ 4ns @ 500MHz BW ………………………................. …………… Quiet time Active time Symbol Interval Francois Chin (I2R)

5. Minimum PRF Requirements Francois Chin (I2R)

6. Frequency Plan Band No. 4 1 2 3 3 4 5 GHz 3.25 3.5 3.75 4.25 4.5 4.75 Francois Chin (I2R)

7. Main Features of proposed system Proposal main features: • Impulse-radio based (pulse-shape independent) • Common synchronisation / ranging preamble signaling for different classes of nodes / type of receivers (coherent / differential / noncoherent) • Band Plan based on multiple 500 MHz bands (center band mandatory) and optional wider bandwidth (1.5 GHz+) concentric with center band • Robustness against SOP interference • Robustness against other in-band interference • Scalability to trade-off complexity/performance Francois Chin (I2R)

8. Types of Receivers Supported • Coherent Detection: The phase of the received carrier waveform is known, and utilized for demodulation • Differential Chip Detection: The carrier phase of the previous signaling interval is used as phase reference for demodulation • Non-coherent Detection: The carrier phase information (e.g.pulse polarity) is unknown at the receiver Francois Chin (I2R)

9. Proposed System Parameters (528 MHz) Francois Chin (I2R)

10. Frame Format 2 1 0/4/8 n 2 Octets: Data Payload MAC Sublayer Frame Cont. Seq. # Address CRC MHR MSDU MFR Data: 32 (n=23) ?? For ACK: 5 (n=0) 1 1 Octets: PHY Layer Frame Length Preamble SFD MPDU SHR PHR PSDU PPDU Francois Chin (I2R)

11. TG4a Baseline – On Common Signaling • Points of Agreement for UWB signalling • Modulation scheme should admit multiple classes of receivers • Transmitter based on deterministic pulse structures • Should allow reception by coherent, differentially-coherent (can be TR) and non-coherent receivers • Provision for homogeneous operation when membership supports it • Ternary modulation • Specific modulation format TBD • Sub-banding: • Center of three bands is mandatory • Other two optional • Wider bandwidth (1.5 GHz+) concentric with center band is optional • CDMA within frequency bands • Harmonic chip rate – integer relationship between center frequency and chip rate • Consider ways to avoid Japanese UNII band (shift band lower) • Integer-plus-half is also proposed, some concerns with DC balance • Maintain 3.1 corner • Constant PRF is desired as possible • Specific band plan - TBD • Cost effective reference frequency with appropriate PPM • Specific frequency and tolerance is TBD • Potential for optional chirp mode (at best, if and where allowed) Source - 15-05-0172-03-004a-abd-merged-uwb-proposal-ieee802-15-tg4a Francois Chin (I2R)

12. Criteria of Code Sequence Design • The code sequence should have good auto-correlation properties for synchronisation and ranging for all the below receivers • Coherent receiver • Differential chip receiver • Energy detection receiver • The sequence Set should have orthogonal (or near orthogonal) cross correlation properties to minimise symbol decision error Francois Chin (I2R)

13. Base Sequence Set • 31-chip Ternary Sequence set are chosen • Only one sequence and one fixed band (no hopping) will be used by all devices in a piconet • Logical channels for support of multiple piconets • 6 sequences = 6 logical channels (e.g. overlapping piconets) for each FDM Band • The same base sequence will be used to construct the symbol-to-chip mapping table Francois Chin (I2R)

14. Good Properties of the Mapping Sequence • Cyclic nature, leads to simple implementation • Low DC value for each sequence • The same code sequence will be used for synchronisation, ranging, data communications & SOP interference suppression Francois Chin (I2R)

15. Ternary – Bipolar – Unipolar Conversion Ternary ± → + 0 → - Bipolar This is in fact m-Sequences! + → + - → 0 Unipolar Francois Chin (I2R)

16. Properties of M-Sequence Transmit – Unipolar M-Seq [+ + + 0 0 0 + + 0 + + + 0 + 0 + 0 0 0 0 + 0 0 + 0 + + 0 0 + + ] repeated 4x Receive – Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] Francois Chin (I2R)

17. Properties of M-Sequence Transmit – Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] repeated 4x Receive – Unipolar M-Seq [+ + + 0 0 0 + + 0 + + + 0 + 0 + 0 0 0 0 + 0 0 + 0 + + 0 0 + + ] Francois Chin (I2R)

18. Properties of M-Sequence Transmit – Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] repeated 4x Receive – Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + +] Francois Chin (I2R)

19. How to make use of these properties? Francois Chin (I2R)

20. Synchronisation Preamble • M-sequences has excellent autocorrelation properties • Synchronisation / Ranging Preamble is constructed by repeating the base sequence • Common Signaling (Mode 1) • Ternary for e.g. Beacon Packet • Receiver-specific signaling (Mode 2) • Ternary for Energy Detector • Bipolar for Coherent and Differential Chip Detectors • Long preamble for distant nodes is constructed by further symbol repetition Francois Chin (I2R)

21. Bipolar Signaling for Synchronisation & Ranging Pulse Repetition Interval ~ 30ns • Receiver-specific signaling (Mode 2) • for Coherent and Differential Chip Detectors 1 2 3 4 5 6 7 8 30 31 ………………………… Non0inverted pulses are blue, Inverted pulses are green. Synchronisation / Ranging preamble = Binary Base Sequence repeated For K times… …………… …………… ................. Symbol Interval ~940ns Symbol Interval ~940ns Francois Chin (I2R)

22. Ranging - Coherent Detector Criteria/Target – ZERO autocorrelation sidelobes for best leading edge detection Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] In AWGN RF& LNA ADC LPF I Correlator Local Oscillator @ TX center frequency PN sequence Mag 90 phase shift ADC LPF Q Correlator Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] Francois Chin (I2R)

23. Sync - Coherent Detector Criteria/Target – balance max post-despreading SNR and low auto-correlation sidelobes Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] In AWGN RF& LNA ADC LPF I Correlator Local Oscillator @ TX center frequency PN sequence Mag 90 phase shift ADC LPF Q Correlator Unipolar M-Seq [+ + + 0 0 0 + + 0 + + + 0 + 0 + 0 0 0 0 + 0 0 + 0 + + 0 0 + + ] Francois Chin (I2R)

24. What about Diff. Detection? Associated Differential Sequences (e.g. Seq#1) Ternary Diff(Ternary) Base Sequence #1 Differential ± → + 0 → - Bipolar Diff(Bipolar) Differential + → + - → 0 + → 0 Unipolar Diff(Unipolar) Francois Chin (I2R)

25. Despreader BPF PRI Ranging – Differential Chip Detector Criteria/Target – ZERO autocorrelation sidelobes for best leading edge detection Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] Diff(Bipolar) [+ + - + + - + - - + + - - - - - + + + - - + - - - + - + - + + ] In AWGN Diff(Unipolar) [0 0 - 0 0 - 0 - - 0 0 - - - - - 0 0 0 - - 0 - - - 0 - 0 - 0 0 ] Francois Chin (I2R)

26. Ternary Signaling for Synchronisation & Ranging • -Common signaling (Mode 1) for ALL Detectors • -Receiver-specific signaling (Mode 2) for ED Pulse Repetition Interval ~ 30ns 1 2 3 4 5 6 7 8 30 31 ………………………… Non-inverted pulses are blue, Inverted pulses are green. Synchronisation / Ranging preamble = Binary Base Sequence repeated For K times… …………… …………… ................. Symbol Interval ~940ns Symbol Interval ~940ns Francois Chin (I2R)

27. Sync & Ranging - Energy Detector Criteria/Target – balance max post-despreading SNR and low auto-correlation sidelobes Ternary Seq [+ - - 0 0 0 + - 0 + + + 0 + 0 - 0 0 0 0 + 0 0 - 0 - + 0 0 - - ] After Square Law & Integration in PRI Unipolar M-Seq [+ + + 0 0 0 + + 0 + + + 0 + 0 + 0 0 0 0 + 0 0 + 0 + + 0 0 + + ] In AWGN Soft output Noncoherent detection of OOK Sliding Correlator LPF / integrator BPF ( )2 ADC Sample Rate 1/Tc {1,-1} Binary Sequence Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] Francois Chin (I2R)

28. Ranging: Code Sequences for different Receiver Criteria/Target – ZERO autocorrelation sidelobes for best leading edge detection Francois Chin (I2R)

29. Communication: Code Sequences for different Receiver Criteria/Target – Max SNR and min inter-sequence interference after despreading Francois Chin (I2R)

30. Snychronisation: Code Sequences for different Receiver Criteria/Target – balance max post-despreading SNR and low auto-correlation sidelobes Francois Chin (I2R)

31. Relationship Between different Sequences Only these 2 are TX Sequences, the rest are Despread Sequences Ternary Diff(Ternary) Base Sequence #1 Differential ± → + 0 → - Bipolar Diff(Bipolar) Differential + → + - → 0 + → 0 Unipolar Diff(Unipolar) Francois Chin (I2R)

32. Transmit & Receive Sequences for different Detectors in different Applications Base Sequence #1 i.e.What is each sequence for? Ternary Diff(Ternary) Bipolar Diff(Bipolar) Diff(Unipolar) Unipolar Francois Chin (I2R)

33. Data Comms:Transmission Mode Francois Chin (I2R)

34. Modulation & Coding (Mode 1) Binary data From PPDU Symbol- to-Chip Bit-to- Symbol Zero Padding Symbol Repetition Pulse Generator Bit to symbol mapping: group every 2 bits into a symbol Symbol-to-chip mapping: Each 2-bit symbol is mapped to one of 4 31-chip sequence, according to 4-ary Ternary Orthogonal Keying Zero Padding: suggested 9 PRI for reducing inter-symbol interference Symbol Repetition: for data rate and range scalability Pulse Genarator: • Transmit Ternary pulses at PRF = 33MHz {0,1,-1} Ternary Sequence Francois Chin (I2R)

35. Symbol Mapping for Mode 1: Grey 4-ary Ternary Orthogonal Keying + Zero Padding Base Sequence #1 Zero Padding Francois Chin (I2R)

36. Modulation & Coding (Mode 2) Binary data From PPDU Symbol- to-Chip Ternary- Bipolar Bit-to- Symbol Zero Padding Symbol Repetition Pulse Generator Bit to symbol mapping: group every 2 bits into a symbol Symbol-to-chip mapping: Each 2-bit symbol is mapped to one of 4 31-chip sequence, according to 4-ary Bipolar Orthogonal Keying Ternary to Binary conversion: (-1/+1 → 1,0 → -1) Zero Padding: suggested 9 PRI for reducing inter-symbol interference Symbol Repetition: for data rate and range scalability Pulse Genarator: • Transmit bipolar pulses at PRF = 33MHz {1,-1} Binary Sequence {0,1,-1} Ternary Sequence Francois Chin (I2R)

37. Symbol Mapping for Mode 2: Bipolar Orthogonal Keying + Zero Padding (after Ternary – Binary Conversion) Binary Base Sequence #1 Zero Padding Francois Chin (I2R)

38. Bipolar Signaling for Symbol ’00’ Pulse Repetition Interval ~ 30ns 1 2 3 4 5 6 7 8 30 31 ………………………… Non0inverted pulses are blue, Inverted pulses are green. ………………………................. …………… Quiet time 9 PRI ~272ns Active time ~940ns Symbol Interval ~1.212us Francois Chin (I2R)

39. Code Sequence Properties & Performance • AWGN Performance • Multipath Performance • For Coherent Symbol Detector • For Differential Chip Detector (to be included later) • For Energy Detector Francois Chin (I2R)

40. Coherent Detector Multipath Performance Note - Effect of conv encoder is not included Francois Chin (I2R)

41. Energy Detector Multipath Performance Note - Effect of conv encoder is not included Francois Chin (I2R)

42. Proposed Optional Wider Band System Francois Chin (I2R)

43. Summary The proposed Impulse-radio based system: • has common ternary signaling that • Can be received simultaneously by different types of receivers, namely coherent, differential, and energy detectors • Can be used for both synchronisation and ranging simultaneously • Synchronisation & Ranging –Repeated Base Sequence (Ternary or Binary) • Simple sliding correlator can be used for Ranging & Sync • Data Communications – Orthogonal Keying Symbol (with cyclic shift version of base sequence + zero padding) • Is robust against SOP interference Francois Chin (I2R)

44. Backup Slides Francois Chin (I2R)

45. How Energy Detector handle inter- pulse interference? Francois Chin (I2R)

46. Energy Detector Sees An Equivalent Unipolar Sequence after integration in PRI Pulse Repetition Interval ~ 30ns d5 d1 d2 d3 d4 d6 d7 Ternary signaling Non-inverted pulses are blue, Inverted pulses are red. After Square Law & Integration in PRI cj=dj2 Sequence become Unipolar e1 e2 e3 c5 c1 c2 c3 c4 c6 c7 More Noise due to cross terms + PRI T1 T2 T3 T4 integrator Output is a convolution of the equivalent Unipolar Sequence with a PRI-spaced tap-delay-line channel, each tap comprising multipath energy within a correponding PRI Francois Chin (I2R)

47. Soft output e1 e1 e2 e2 e3 e3 RAKE combiner Noncoherent detection of OOK Soft Despread PRI PRI LPF / integrator BPF ( )2 ADC T1 T1 T2 T2 T3 T3 T4 T4 Sample Rate 1/Tc {1,-1} Binary Sequence Figure 1. The block diagram of energy detection receiver using soft despreader and RAKE combiner In Multipath Channels … Ternary Seq [+ - - 0 0 0 + - 0 + + + 0 + 0 – 0 0 0 0 + 0 0 - 0 - + 0 0 - - ] Unipolar M-Seq [+ + + 0 0 0 + + 0 + + + 0 + 0 + 0 0 0 0 + 0 0 + 0 + + 0 0 + + ] Despread Sequence = Bipolar M-Seq [+ + + - - - + + - + + + - + - + - - - - + - - + - + + - - + + ] Francois Chin (I2R)