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: [Multicarrier-UWB] Date Submitted: [3 March 2003] Source: [Ahmed H Tewfik] Company [University of Minnesota] Address [Dept. of Electrical and Computer Engineering, Room 4-174 EECS Bldg.,Minneapolis, MN 55455] Voice:[612-625-6024], FAX: [612-625-4583], E-Mail:[tewfik@ece.umn.edu] Re: [n/a] Response to a Call for Contributions Task Group 3a Call For Intent and Proposals, November 2002, updated January 2003, 02371r0P802-15_SG3a-5_Criteria.doc Abstract: [We propose a multi-carrier UWB system for WPAN communications. We describe system design issues and proposed transmitter and receiver structures. We also provide a self-evaluation of the proposed system.] Purpose: [For consideration by 802.15.3a task group.] 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. Tewfik/Saberinia, U. of MN

2. Multicarrier-UWB H. Tewfik and E. Saberinia University of Minnesota Tewfik/Saberinia, U. of MN

3. Overview • Unified view of UWB • Multicarrier-UWB • Proposed system • N-tone sigma-delta modulators • Self-evaluation Tewfik/Saberinia, U. of MN

4. uTp(t) Tp Unified View of UWB • General form • Special cases • TM-UWB • DS-UWB • MC-UWB Info. signal x pulse train Tewfik/Saberinia, U. of MN

5. Unified View of UWB • Advantageous to view p(t) as: p(t)= [pulse train]x[spreading sequence] Info. signal x x pulse train FH or DS Spreading sequence Tewfik/Saberinia, U. of MN

6. Desirable Attributes Baseband signal replicas around Fourier components at fk= k/T • Replication in time and frequency domains needed for reliable communications • Poor spectral use • Spectral gaps • Spectral shaping due to S(f) Shaping due to s(t) pulse train x Info. signal u(t) 1/NT NT 1/T Tewfik/Saberinia, U. of MN

7. Desirable Attributes Fill the gaps between spectral lines at fk= k/T • Fill the gaps between the spectral lines Shaping due to s(t) pulse train x Info. signal u(t) 1/NT NT 1/T Tewfik/Saberinia, U. of MN

8. Desirable Attributes Matched filter MC-UWB channel Tewfik/Saberinia, U. of MN

9. Desirable Attributes • Ambiguity function of p(t) • Would like:Cp(t,f)  0except for the origin (t,f) =(0,0) Tewfik/Saberinia, U. of MN

10. Multicarrier UWB • Elemental signal • c(n): Costas’ sequence • Time resolution: Tc/N • Frequency resolution:1/NT Tewfik/Saberinia, U. of MN

11. Multicarrier UWB • Advantages • Good time and frequency resolution • Time resolution decoupled from • elementary pulse duration • inter-pulse separation More flexibility for design Tewfik/Saberinia, U. of MN

12. Design Approach • Select elementary pulse duration based on peak power and pulse length limitations and desired sidelobe behavior in frequency domain • Select inter-pulse separation and number of pulse based on channel spread and average power limitation • Select TC to fill available bandwidth Tewfik/Saberinia, U. of MN

13. Proposed System • System parameters: • N=30, T=9nsec, Ts=1nsec, Tc=4.5nsec • 8 subcarriers with TCM 32-ary QAM • 2 Pilots MC-UWB signal data 1 bit D/A x TCM-QAM 10 tone IFFT Modulation: Carrier + FH spreading Tewfik/Saberinia, U. of MN

14. Re( ) N-Tone S -D 1 bit D/A X FH c(n) VCO I FFT S TCM- QAM p/2 N-Tone S -D 1 bit D/A X Im( ) Transmitter Tewfik/Saberinia, U. of MN

15. Proposed System 10 tone FFT Costas sequence modulated filterbank 1 bit A/D Pilot correlation Demodulator AGC Decision S data Tewfik/Saberinia, U. of MN

16. + X(n) 1 bit quantizer + - Traditional Sigma Delta y(n) Tewfik/Saberinia, U. of MN

17. Lowpass Filtering and downsampling + 1 bit quantizer oversample - + Traditional Sigma Delta D/A X(t) Multibit X(n) Analog switched capacitor implementation Tewfik/Saberinia, U. of MN

18. + Traditional Sigma Delta D/A Analog Lowpass Filtering + X(n) 1 bit quantizer 1 bit D/A L - X(t) upsample • Higher order SD preferred: • Better noise shaping • Eliminate spurious tones Tewfik/Saberinia, U. of MN

19. N Tone Sigma Delta + X(n) 1 bit quantizer + y(n) (e.g., output of N point IFFT) - Tewfik/Saberinia, U. of MN

20. N Tone Sigma Delta “Instantaneous” Frequency spectrum Filter outputs Tewfik/Saberinia, U. of MN

21. N Tone Sigma Delta Average Frequency spectrum Tewfik/Saberinia, U. of MN

22. Multiple Piconets • Simultaneous operation achieved by proper selection of: • Pulse train p(t) • Costas sequence c(n) • Time hopping • Carrier frequencies Tewfik/Saberinia, U. of MN

23. Self-Evaluation Tewfik/Saberinia, U. of MN

24. Self-Evaluation Tewfik/Saberinia, U. of MN

25. Self-Evaluation Tewfik/Saberinia, U. of MN

26. Self-Evaluation Tewfik/Saberinia, U. of MN

27. Conclusion • Multi-carrier UWB offers ability to use traditional baseband modulation schemes and achieve desired performance • Implementation simplified by use of N-tone sigma-delta modulators Tewfik/Saberinia, U. of MN