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: [18 July 2005] Source: [Francois Chin, Yuen-Sam Kwok, Sai-Ho Wong, Zander Lei,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 values for Mandatory and optional wider band systems • Impulse Radio Signaling Proposal • Common Signaling for different receivers, for Synchronisation, Ranging and Data Communications • Deterministic Pulse structures • Optimal Receiver Code Sequences Francois Chin (I2R)

3. Minimum PRF Requirements (BW~500MHz) • Key Requirement is to meet CMOS Tx Vpp constraint • For Ternary signaling • 1.0Vpp @ 15.5MHz CRF without backoff & perfect antenna • 1.2Vpp @ 15.5MHz CRF without backoff & 30% (or 1.5dB) feed loss • 1.0Vpp @ 15.5MHz CRF without 1.5dB backoff & 30% (or 1.5dB) feed loss Francois Chin (I2R)

4. Minimum PRF Requirements (BW~1.5GHz) • Key Requirement is to meet CMOS Tx Vpp constraint • For Ternary signaling • 1.0Vpp @ 124MHz CRF without backoff & perfect antenna • 1.2Vpp @ 124MHz CRF without backoff & 30% (or 1.5dB) feed loss • 1.0Vpp @ 124MHz CRF without 1.5dB backoff & 30% (or 1.5dB) feed loss Francois Chin (I2R)

5. 124 MHz CRF Mode is logical… • ~1.5GHz system, 3x larger bandwidth means • 3x shorter pulse duration • 3x higher average transmit power • The keep the same peak transmit power, ~1.5GHz system should have ~9x higher CRF (or PRF), compared to ~500MHz system • 124MHz CRF = 8 x 15.5 MHz CRF • Or in terms of PRF, 62 MHz = 8 x 7.75 MHz Francois Chin (I2R)

6. Minimum numbers of Chip Rates • After considering antenna feed loss and PSD backoff, we have min 2 CRFs • ~15.5MHz for ~500MHz systems • ~124MHz for ~1500MHz systems Francois Chin (I2R)

7. Main Features of proposed Impulse Radio Signaling Proposal main features: • Impulse-radio based (pulse-shape independent) • Ternary Codes for Common Preamble & Data signaling for different classes of nodes / type of receivers (coherent / differential / noncoherent) • Perfect balance ternary sequences for synchronisation & ranging preambles – Perfect Autocorrelation for coherent and energy detectors • M-ary signaling for data transmission to achieve higher spreading gain - Robustness against SOP interference Francois Chin (I2R)

8. Key Features of proposed System • Impulse-radio based (pulse-shape independent) • Chip Repetition Frequency = ~15.5MHz (corresponding to PRF of ~7.75MHz) • 1 Mbps mandatory and 10Mbps optional modes • Ternary Codes for Common Preamble & Data signaling for different classes of nodes / type of receivers (coherent / differential / noncoherent) • 31-Chip Perfect Balance Ternary Sequences (PBTS) for synchronisation & ranging preambles – Perfect Autocorrelation for coherent and energy detectors • 16-ary Ternary Orthogonal Keying (derived from 31-chip sequence PBTS) for data transmission to achieve higher spreading gain - Robustness against SOP interference Francois Chin (I2R)

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

10. Base Sequence Set (31-chip Ternary) These are Wideband Access-I2R proposed Perfect Balance Ternary Sequences for Preambles for Ranging • 31-chip Ternary Sequence Set • Only one base 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 500MHz Band • The same base sequence will be used for • acquisition / ranging; and • Data transmissionvia symbol-to-chip mapping Francois Chin (I2R)

11. Base Sequence Properties (Auto-Corr.) • Perfect balance ternary sequences for synchronisation & ranging preambles – • Perfect Autocorrelation for coherent and energy detectors Francois Chin (I2R)

12. Base Sequence Properties (Cross-Corr.) First 3 sequences have lowest possible cross-correlation values… Francois Chin (I2R)

13. Spectral PAR (PSD Backoff) PSD Backoff ~ 1.0dB @ 15.5 MHz Francois Chin (I2R)

14. Synchronisation Preamble • The Ternary Base Sequence has excellent autocorrelation properties • Synchronisation / Ranging Preamble is constructed by repeating the preamble • Noted that with this new improved ternary sequences, there is no need for Receiver-specific signaling Francois Chin (I2R)

15. Ternary Signaling for Preambles CHIP Repetition Interval ~ 65ns 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 ~2us Symbol Interval ~2us Francois Chin (I2R)

16. Modulation & Coding Coded Bits Zero Padding Pulse Generator Symbol Repetition Symbol- to-Chip Bit-to- Symbol Scrambling Bit to symbol mapping: group every 4 bits into a symbol Symbol-to-chip mapping: Each 2-bit symbol is mapped to one of 16 31-chip sequence, according to 16-ary Ternary Orthogonal Keying Zero Padding: suggested 1 PRI for reducing inter-symbol interference Symbol Repetition: for data rate and range scalability Scrambling: with bipolar sequence @ 15.5MHz, to suppress cross correlation sidelobes due to excessive delay spread Pulse Genarator: Transmit Ternary pulses @ 15.5MHz {0,1,-1} Ternary Sequence Francois Chin (I2R)

17. Symbol-to-Chip Mapping: Gray coded 16-ary Ternary Orthogonal Keying Base Sequence #1 1 zero padding Francois Chin (I2R)

18. Code Sequences for different Receivers • For both Preamble and Data • Ternary to Bipolar conversion ± → + 0 → - Francois Chin (I2R)

19. Cross Sequence Correlation Properties for Coherent Receiver For Coherent Detector, RX Mapping Matrix = TX Mapping Matrix RX Mapping Matrix * TX Mapping Matrix' = Francois Chin (I2R)

20. Rx Sequence for Energy Detector Ternary to Bipolar conversion of Base Sequence #1 Francois Chin (I2R)

21. Sync & Ranging - Energy Detector operation (example) 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)

22. Cross Sequence Correlation Properties for Energy Detector For Energy Detector, RX Mapping Matrix = Ternary2Bipolar(TX Mapping Matrix) RX Mapping Matrix * abs(TX Mapping Matrix)' = Francois Chin (I2R)

23. Why M-ary Orthogonal Keying ? • Good coding gain as M-ary Orthogonal Keying is power-limited coding • More coding gain is achieved with higher M values • Marginal gain for M > 16 • Robust against SOP interference & inter-pulse interferencedue to high despreading gain per M-ary symbol Francois Chin (I2R)

24. Simulation Results • AWGN Performance & Multipath Performance • For Coherent Symbol Detector • For Energy Detector • For differential Chip Detector (to be provided later) Francois Chin (I2R)

25. Proposed Mandatory System Parameters Francois Chin (I2R)

26. Multipath Performance (1 Mbps, 500MHz BW) • Random transmit scrambling seq. • Coherent and energy detectors • AWGN, CM1 & CM8 • 1-Rake & 4-Rake • Ideal Channel acquisition + timing estimation • Benefit of ½ rate CC not obvious in isolated piconet operation; advantage may be in SOP operation Francois Chin (I2R)

27. SOP + Multipath (1 Mbps, 500MHz BW) To be provided later Francois Chin (I2R)

28. Proposed Mandatory System Parameters (Max Bit Rate Mode) Francois Chin (I2R)

29. Multipath Performance (10 Mbps, 500MHz BW) • No Ternary Ortho.Keying • Coherent detector only • AWGN, CM1 • 1-Rake & 4-Rake • Ideal Channel acquisition + timing estimation Francois Chin (I2R)

30. Proposed Optional Wider Band ~ 1.5GHz systems Francois Chin (I2R)

31. Key Features of proposed wider band system • Impulse-radio based (pulse-shape independent) • Chip Repetition Frequency = ~124MHz (corresponding to PRF of ~62MHz) • 1 Mbps mandatory and 10Mbps optional modes • Ternary Codes for Common Preamble & Data signaling for different classes of nodes / type of receivers (coherent / differential / noncoherent) • 127-Chip Perfect balance ternary sequences for synchronisation & ranging preambles – Perfect Autocorrelation for coherent and energy detectors • 16-ary Ternary Orthogonal Keying (with 256-chip sequence) for data transmission to achieve higher spreading gain - Robustness against SOP interference, especially in 1.5GHz system (without FDMA for SOP) Francois Chin (I2R)

32. Base Sequence Set (127-chip Ternary) These are Wideband Access-I2R proposed Perfect Balance Ternary Sequences for Preambles for Ranging • 127-chip Ternary Sequence Set • Only one base sequence and one fixed band (no hopping) will be used by all devices in a piconet • Logical channels for support of multiple piconets • 5 sequences = 5 logical channels (e.g. overlapping piconets) for 1500MHz Band • The same base sequence will be used for • acquisition / ranging; and • Data transmissionvia symbol-to-chip mapping Francois Chin (I2R)

33. Ternary Signaling for Preambles CHIP Repetition Interval ~ 8.1ns 1 2 3 4 5 6 7 8 126 127 ………………………… Non-inverted pulses are blue, Inverted pulses are green. Synchronisation / Ranging preamble = Binary Base Sequence repeated For K times… …………… …………… ................. Symbol Interval ~1.03us Symbol Interval ~1.03us Francois Chin (I2R)

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

35. Multipath Performance (1 Mbps, 1500MHz BW) • Random Transmit scrambling seq. • Coherent and energy detectors • AWGN, CM1 & CM8 • 1-Rake & 4-Rake • Ideal Channel acquisition + timing estimation • Benefit of ½ rate CC not obvious in isolated piconet operation; advantage may be in SOP operation Francois Chin (I2R)

36. SOP + Multipath (1 Mbps, 1500MHz BW) To be provided later Francois Chin (I2R)

37. Proposed Optional Wider Band System (Max Bit Rate) Francois Chin (I2R)

38. Multipath Performance (10 Mbps, 1500MHz BW) • Random Transmit scrambling seq. • Coherent and energy detectors • AWGN, CM1 & CM8 • 1-Rake & 4-Rake • Ideal Channel acquisition + timing estimation • Benefit of ½ rate CC not obvious in isolated piconet operation; advantage may be in SOP operation Francois Chin (I2R)

39. Summary The proposed Impulse-radio based system: • has ternary signaling only that • Can be received simultaneously by different types of receivers, namely coherent, differential, and energy detectors • Can be used for both Preamble and Comm. simultaneously • Synchronisation & Ranging –Repeated Ternary Base Sequence for preambles • Simple sliding correlator can be used for Ranging & Sync • Data Communications – 4bit/symbol Ternary Orthogonal Keying Symbol (with cyclic shift version of base sequence + zero padding) • Good coding gain due to M-ary orthogonal keying • Is robust against SOP interference due to high spreading gain per symbol Francois Chin (I2R)