1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ WAVEFORM MODULATED LOW RATE UWB SYSTEM - Proposal for 15.4a alt PHY ] Date Submitted: [Jan., 2005] Source: [Soo-Young Chang] Company [California State University, Sacramento] Address [6000 J Street, Dept. EEE, Sacramento, CA 95819-6019 ] Voice:[916 278 6568], FAX: [916 278 7215], E-Mail:[sychang@ecs.csus.edu] Re: [ This submission is in response to the IEEE P802.15.4a Alternate PHY Call for Proposal ] Abstract:[ This document describes the waveform modulated UWB proposal for IEEE 802.15 TG4a.] Purpose:[ For discussion by IEEE 802.15 TG4a.] 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. Soo-Young Chang, CSUSSlide 1Submission Jan. 2005 doc.: IEEE 802.15-05-0028-01-004a

2. WAVEFORM MODULATED LOW RATE UWB SYSTEM - Proposal for 15.4a alt PHY- Soo-Young Chang California State University, Sacramento Jan. 2005 Soo-Young Chang, CSUSSlide 2Submission doc.: IEEE 802.15-05-0028-01-004a

3. INTRODUCTION Use short duration impulses: purely processed in time domain, not in frequency domain –Simple concept –Simple digital processing  Low complexity  Low cost –No components for processing frequency information (e.g. filter, osc., etc.) –High locating accuracy and fast ranging with very short duration pulses –Stealth mode of operation possible with relatively small RF signature by coding frequency subbands with orthogonal codes –Excellent co-existence capability due to adaptive frequency band usage – flexible to eliminate forbidden bands (e.g. UNII band) Jan. 2005 Soo-Young Chang, CSUSSlide 3Submission doc.: IEEE 802.15-05-0028-01-004a

4. PLAUSIBLE MYTHS Myth 1 –‘Low rate needs less power consumption.’  With high rates, low power consumption can be achieved. Myth 2 –‘Digital implementation needs more complexity and is not easily realizable with the state-of-the art technologies.’  Digital implementation can be realized with less complexity and provide more flexibility. Myth 3 –‘Higher frequency is not easy to manage or implement.’  Unless high power is not considered, digital processing method can be applied for higher frequency band. Myth 4 –‘Since this technology was not realizable yesterday, today also it is not easy to realize.’  Since technologies advances rapidly, more sophisticated and conceptual ideas should be considered for future applications. Jan. 2005 Soo-Young Chang, CSUSSlide 4Submission doc.: IEEE 802.15-05-0028-01-004a

5. CONSIDERATIONS FOR LOW RATE UWB (1) Frequency band –Enjoy full frequency band assigned: 3.1 – 10.6 GHz in the US –Only max power spectral density is limited: Transmitted power is proportional to the bandwidth –Pulse width is inversely proportional to bandwidth: more accurate ranging possible for time based ranging –Large bandwidth entails low fading  High rate sampling is needed to process using digital methods  To overcome this problem, new processing method should be devised Transmit power –Enjoy full power transmitted under frequency mask if waveforms have the spectrum similar to frequency mask –Max power will be -41.3dBm/MHz*7500MHz = -2.54dBm = 0.5mW –More transmit power needs more power consumption ???  New waveform is needed to fit exactly to frequency mask Jan. 2005 Soo-Young Chang, CSUSSlide 5Submission doc.: IEEE 802.15-05-0028-01-004a

6. CONSIDERATIONS FOR LOW RATE UWB (2) Data rate –In TRD, “low rate” is suggested with expectation to reduce power consumption and complexity/cost –Power consumption is mainly proportional to the time of signal transmission and processing –No need to reduce data rates if higher rates possible with the same cost/efforts with higher data rate, less probability of conflict with other transmissions for CSMA and higher success rate with ack –More pulses may be transmitted for the same information with higher rates: more redundancy can be achieved –The amount of information delivered is the key issue for any communication systems The higher the data rate is, the less time it takes to deliver.  More sophisticated signal processing for higher rate is inevitable. Jan. 2005 Soo-Young Chang, CSUSSlide 6Submission doc.: IEEE 802.15-05-0028-01-004a

7. CONSIDERATIONS FOR LOW RATE UWB (3) Full digital processing –Provide full flexibility for any change in signal environments, system concepts and requirements –May also be compatible with a variety of complex digital modulation schemes –Eliminate the cost and complexity of a down conversion stage  Sophisticated digital signal processing technologies needed including high speed ADCs and DACs with sampling rate > 1 Gsamples/sec Jan. 2005 Soo-Young Chang, CSUSSlide 7Submission doc.: IEEE 802.15-05-0028-01-004a

8. FREQUENCY PLAN Flexible enough to satisfy any frequency mask and to avoid any forbidden bands  pulse waveforms can be adaptively tailored to any frequency mask applied With FCC mask, 3.1GHz to 10.6 GHz full frequency band is used to enjoy more transmitted power  3.8 dB more power used than Gaussian pulse’s case in the same frequency band  3.8 dB more margin for link budget Jan. 2005 Soo-Young Chang, CSUSSlide 8Submission doc.: IEEE 802.15-05-0028-01-004a

9. FREQUENCY SUBBANDS Whole frequency band under FCC mask is divided into 4 groups Each group has 4 subbands –BW of a subband = (10.6-3.1) GHz /16 = 469 MHz –Each subband has its own waveform f subband 1 subband 2subband 3subband 4 f group 1 group 2group 3group 4 3.1 GHz10.6 GHz w 21 w 22 w 23 w 24 base waveform Jan. 2005 Soo-Young Chang, CSUSSlide 9Submission doc.: IEEE 802.15-05-0028-01-004a

10. PULSE WAVEFORM OF SUBBAND Pulse waveform shape –Mathematical derivation/expression –Shape: duration: 9 ns –Spectrum: almost flat throughout whole band How can pulses be generated –Digital way?  Overlapped with various delays  can be generated with relatively lower sampling rate DACs 100 samples/waveform: 16 waveforms/group for binary representation 81 waveforms/group for ternary representation 1600 or 8100 sample information stored in ROM per group  1.6 or 8.1 Kbytes ROM needed to store waveform information if 8 bits/sample is adopted Generate waveforms using DACs which has a sampling rate of 1 Gsamples/sec –Analog way? No idea –4 digital ways considered in this proposal How can delay devices for TX and RX be implemented?  Cost/accuracy/step size are the key issues Jan. 2005 Soo-Young Chang, CSUSSlide 10Submission doc.: IEEE 802.15-05-0028-01-004a

11. TYPICAL PULSE WAVEFORM AND ITS SPECTRUM For each subband, there is one waveform which has flat spectrum as shown in the above. Group i has four base waveforms: w i1, w i2, w i3, and w i4 Group i has 16 waveforms: m i1, m i2, m i3,..., m i16 m ij,=a* w i1 +b* w i2 +c* w i3 +d* w i4 where a, b, c, and d are determined by modulation method applied Jan. 2005 Soo-Young Chang, CSUSSlide 11Submission doc.: IEEE 802.15-05-0028-01-004a

12. POSSIBLE MODULATIONS OOK –Two levels: +1, 0 Anti-podal: BPSK –Two levels: +1, -1 OOK + Anti-podal –Three levels: +1, 0, -1 n level modulation nQAM Jan. 2005 Soo-Young Chang, CSUSSlide 12Submission doc.: IEEE 802.15-05-0028-01-004a

13. MODULATION/MA EFFICIENCY Energy or power efficient?joule/sec –Energy=power*time –Power limited by FCC mask Pmax=-41.3dBm/MHz*7500MHz=-2.54dBm=0.5mW  To use more energy, more time needs to be transmitted  totally related to time  for UWB, BW>500MHz or fractional BW>20% of fc  short duration pulses  use multiple pulses for one bit (or symbol)  need more power under frequency mask to have higher power  power constrained with frequency mask for UWB case  new waveform needed to have more transmitted power Spectrally efficient? bit/Hz –Not important for UWB because of plenty of bandwidth Time efficient?bit/sec –For higher rate, more important: for lower rate, less important  more room for flexibility for LR-WPAN –However, as bit duration increases, more power consumption may be required Jan. 2005 Soo-Young Chang, CSUSSlide 13Submission doc.: IEEE 802.15-05-0028-01-004a

14. WAVEFORMS FOR EACH GROUP f group 1 group 2group 3group 4 3.1 GHz10.6 GHz m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 2,1 (t) m 2,2 (t) m 2,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 1,1 (t) m 1,2 (t) m 1,16 (t) m 3,1 (t) m 3,2 (t) m 3,16 (t) m 4,1 (t) m 4,2 (t) m 4,16 (t) Jan. 2005 Soo-Young Chang, CSUSSlide 14Submission doc.: IEEE 802.15-05-0028-01-004a

15. SUBGROUPS FOR EACH GROUP f group 1 group 2group 3group 4 3.1 GHz10.6 GHz m 1,1 (t) m 1,6 (t) m 1,11 (t) m 1,16 (t) m 2,1 (t) m 2,6 (t) m 2,11 (t) m 2,16 (t) m 3,1 (t) m 3,6 (t) m 3,11 (t) m 3,16 (t) m 4,1 (t) m 4,6 (t) m 4,11 (t) m 4,16 (t) m 1,4 (t) m 1,7 (t) m 1,10 (t) m 1,13 (t) m 2,4 (t) m 2,7 (t) m 2,10 (t) m 2,13 (t) m 3,4 (t) m 3,7 (t) m 3,10 (t) m 3,13 (t) m 4,4 (t) m 4,7 (t) m 4,10 (t) m 4,13 (t) m 1,2 (t) m 1,8 (t) m 1,9 (t) m 1,15 (t) m 2,2 (t) m 2,8 (t) m 2,9 (t) m 2,15 (t) m 3,2 (t) m 3,8 (t) m 3,9 (t) m 3,15 (t) m 4,2 (t) m 4,8 (t) m 4,9 (t) m 4,15 (t) m 1,3 (t) m 1,5 (t) m 1,12 (t) m 1,14 (t) m 2,3 (t) m 2,5 (t) m 2,12 (t) m 2,14 (t) m 3,3 (t) m 3,5 (t) m 3,12 (t) m 3,14 (t) m 4,3 (t) m 4,5 (t) m 4,12 (t) m 4,14 (t) SG1 SG2 SG3 SG4 Jan. 2005 Soo-Young Chang, CSUSSlide 15Submission doc.: IEEE 802.15-05-0028-01-004a

16. BASE WAVEFORM FOR ONE GROUP + + + t (ns) 04 For four subbands – assuming each has 1 GHz BW –If smaller BW, larger pulse width Jan. 2005 Soo-Young Chang, CSUSSlide 16Submission doc.: IEEE 802.15-05-0028-01-004a

17. BASE WAVEFORM FOR ONE GROUP For four subbands - for smaller BW, larger pulse width For BW=469 MHz Jan. 2005 Soo-Young Chang, CSUSSlide 17Submission doc.: IEEE 802.15-05-0028-01-004a subband 1 subband 2 subband 3 subband 4

18. EXAMPLES OF WAVEFORMS (OOK) m 1,5 (t) m 1,12 (t) m 1,16 (t) Jan. 2005 Soo-Young Chang, CSUSSlide 18Submission doc.: IEEE 802.15-05-0028-01-004a

19. WAVEFORM FOR DATA STREAM (OOK) Jan. 2005 Soo-Young Chang, CSUSSlide 19Submission doc.: IEEE 802.15-05-0028-01-004a

20. EXAMPLES OF WAVEFORMS (BPSK) m 1,1 (t) m 1,11 (t) m 1,16 (t) Jan. 2005 Soo-Young Chang, CSUSSlide 20Submission doc.: IEEE 802.15-05-0028-01-004a

21. MODULATION PROPOSED Proposed Mod (1) –8 frequency bins are coded with an 8 bit Walsh code and represent one bit using BPSK Proposed Mod (2) –4 waveforms of a subgroup are mapped to 2 bit (quaternary) information ex) m 1,1 (t)  00 m 1,6 (t)  01 m 1,11 (t)  10 m 1,16 (t)  11 –Each user sends information using one subgroup of each group  at one time 8 bit information is delivered –Each waveform is modulated by OOK or BPSK or OOK+BPSK Jan. 2005 Soo-Young Chang, CSUSSlide 21Submission doc.: IEEE 802.15-05-0028-01-004a

22. MAPPING FREQUENCY BINS TO WALSH ENCODED SYMBOLS Jan. 2005 Soo-Young Chang, CSUSSlide 22Submission doc.: IEEE 802.15-05-0028-01-004a

23. DATA RATES 1 Mbps max with 100% overhead  T b = 1/2 Mbps = 500 ns Pulse width = 9 ns  Duty cycle = 2 % Mod type# of waveforms /subgroup # of bits/symbol duration symbol duration (ns) Data rate w/100% overhead (Mbps) Mod (1) BPSK 425002 Mod (2) OOK or BPSK 1685008 500 ns Jan. 2005 Soo-Young Chang, CSUSSlide 23Submission doc.: IEEE 802.15-05-0028-01-004a

24. MULTIPLE ACCESS (1) Possible MAs considered –Frequency hopping (FH) among groups Not efficient because of uncertainty of FCC’s ruling on FH so far and less usage of power –TDMA Less time efficient –Direct-sequence (DS) CDMA Less time efficient and more complex f t Group 1 Group 2 Group 3 Group 4 16 frequency bins time domain bins t4t2t3t1t5 Jan. 2005 Soo-Young Chang, CSUSSlide 24Submission doc.: IEEE 802.15-05-0028-01-004a

25. MULTIPLE ACCESS (2) For each subband, one base waveform exists –16 base waveforms: w 11 (t), w 12 (t), w 13 (t), w 14 (t), w 21 (t),...., w 43 (t), w 44 (t) –Each waveform is almost orthogonal to each other Each group has –16 waveforms for mod (1) or 81 waveforms for mod (2) m 1,1 =0, m 1,2 = w 1, m 1,3 = w 2,...., m 4,16 = w 13 + w 14 + w 15 + w 16 Jan. 2005 Soo-Young Chang, CSUSSlide 25Submission doc.: IEEE 802.15-05-0028-01-004a

26. MULTIPLE ACCESS (3) Correlation where : kth sample of ith waveform of a subband for N samples –Ratio of correlations = autocorrel/crosscorrel for various N values –Orthogonality holds for sinusoidal waveforms with some conditions (Orthogonality condition, refer to next slide), but the waveforms used here are not sinusoidal with some envelope –At receiver, a processing procedure can be used to make pure sinusoidal for a period m ij *m ij =(a* w i1 +b* w i2 +c* w i3 +d* w i4 )(a* w i1 +b* w i2 +c* w i3 +d* w i4 ) where m ij is the waveform transmitted and m ij is the waveform generated at RX After integrate for a one waveform duration, only autocorrelation terms remain Orthogonality can hold at RX during detection –What is the best sampling frequency such that orthogonality can be achievable? Jan. 2005 Soo-Young Chang, CSUSSlide 26Submission doc.: IEEE 802.15-05-0028-01-004a

27. CORRELATIONS # of samples = 180 # of samples = 90 Correlation ratio = autocorrelation/crosscorrelation correlation correlation ratio w 11 w 12 w 13 w 14 w 11 0.020984 1/1 0.0012155 17.264/9.7396 2.2562×10-5 930.05/3957.3 3.4173×10-6 6140.6/9681.8 w 12 0.0012155 17.264/9.7396 0.020984 1/1 6.8651×10-6 305.66/106.69 2.2562×10-5 930.05/3957.3 w 13 2.2562×10-5 930.05/3957.3 6.8651×10-6 305.66/106.69 0.020984 1/1 0.0012155 17.264/9.7396 w 14 3.4173×10-6 6140.6/9681.8 2.2562×10-5 930.05/3957.3 0.0012155 17.264/9.7396 0.020984 1/1 Jan. 2005 Soo-Young Chang, CSUSSlide 27Submission doc.: IEEE 802.15-05-0028-01-004a

28. ORTHOGONALITY OF SINUSOIDS A key property of sinusids is that they are orthogonal at different frequencies. That is, This is true whether they are complex or real, and whatever amplitude and phase they may have. All that matters is that the frequencies be different. Note, however, that the sinusoidal durations must be infinity. For length sampled sinusoidal signal segments exact orthogonality holds only for the hamonics of the sampling rate-divided-by-, i.e., only for the frequencies These are the only frequencies that have a whole number of periods in samples Ex. N=100 for 4 ns pulse duration, fs=25 GHz –fk=k*25*10**9/100=2.5*10**8*k=0.25*k GHz –For any integer k, fk can be determined  center frequencies of each subband can be determined http://ccrma.stanford.edu/~jos/r320/Orthogonality_Sinusoids.html Jan. 2005 Soo-Young Chang, CSUSSlide 28Submission doc.: IEEE 802.15-05-0028-01-004a

29. MAPPING FREQUENCY BINS TO WALSH ENCODED SYMBOLS Jan. 2005 Soo-Young Chang, CSUSSlide 29Submission doc.: IEEE 802.15-05-0028-01-004a

30. MUTIPLE ACCESS (4) A orthogonal set of 8 8-bit Walsh codes is used –Max autocorrelation, min (or zero) crosscorrelation each other –One code consists of 8 frequency domain bins –Minimal Hamming distance of this code set is 4 One frequency bin error can be corrected while three bin errors can be detected; works as an ECC code; increases robustness 8 SOPs case –For one user, one code is assigned –One time domain bin is occupied by two codes Each code represents one bit; one time domain bin represents two bits; during one time domain bin two bits are delivered 64 SOPs case –For one user, two codes (16 bits) are assigned –One time domain bin is occupied by two codes two codes represent one bit; one time domain bin represents one bit; one time domain bit deliver one bit Jan. 2005 Soo-Young Chang, CSUSSlide 30Submission doc.: IEEE 802.15-05-0028-01-004a

31. TRANSMITTER STRUCTURE Simple structure with impulse radio concept –FEC encoder –Interleaver –Pulse generator –Modulator –Antenna Data manipulator modulator Pulse generator Data in antenna Source coding Channel coding interleaving This part can be realized using digital processing Jan. 2005 Soo-Young Chang, CSUSSlide 31Submission doc.: IEEE 802.15-05-0028-01-004a

32. TRANSMITTER BLOCK DIAGRAM ROM, group 1 ROM, group 2 ROM, group 3 ROM, group 4 DAC waveform transformer data manipulator S/P converter encoding interleaving encryption input data Jan. 2005 Soo-Young Chang, CSUSSlide 32Submission doc.: IEEE 802.15-05-0028-01-004a

33. RECEIVER STRUCTURE Simple receiver structure –Antenna- Pulse generator –LNA- Location processor –Demodulator –Data detector –De-interleaver –Channel decoder –Synchronizer demodulator Data De-manipulator Pulse generator Synch Information retriever antenna LNA Data out detector location Jan. 2005 Soo-Young Chang, CSUSSlide 33Submission doc.: IEEE 802.15-05-0028-01-004a

34. RECEIVING BLOCK waveform conditioner ADC correlator ROM LNA correlation pulse generator received signal correlation Time correlator concept Jan. 2005 Soo-Young Chang, CSUSSlide 34Submission doc.: IEEE 802.15-05-0028-01-004a

35. LINK BUDGET ANALYSIS AWGN and 0 dBi gain at TX/RX antennas assumed. Fc=5.73GHz ParameterValue Information Data Rate1 Mb/s2 Mb/s1 Mb/s Average TX Power-2.54 dBm Total Path Loss (49.15dB@1m + L2)49.15dB@1m 77.14 dB (@ 30 meters) 67.60 dB (@ 10 meters) 67.60 dB (@ 10 meters) Average RX Power-79.68 dBm-70.14 dBm Noise Power Per Bit-114 dBm-111 dBm-114 dBm RX Noise Figure8 dB Total Noise Power-106 dBm-103 dBm-106 dBm Required Eb/N06.25 dB Implementation Loss2.5 dB3.0 dB2.5 dB Link Margin17.57 dB23.11 dB22.61 dB RX Sensitivity Level-97.25 dBm-93.25 dBm-92.75 dBm Jan. 2005 Soo-Young Chang, CSUSSlide 35Submission doc.: IEEE 802.15-05-0028-01-004a

36. WHY THIS PROPOSAL? More transmit power used under frequency mask –More margin: at least 3 dB more by using full power under any frequency-power constraints with waveforms adaptive to frequency mask  Spectrally efficient / more received signal power  More chance to intercept signals Very simple architecture –Directly generated pulse waveforms using ROM –Processing in digital methods No need to have analog devices (e.g., mixer, LO, integrator, etc)  low cost / low power consumption High location accuracy –Wider bandwidth for each waveforms  narrower pulse width  more accurate location information High adaptability to frequency, data rate, transmit power requirements  high scalability in frequency, data rate, system configuration, waveform, etc. Jan. 2005 Soo-Young Chang, CSUSSlide 36Submission doc.: IEEE 802.15-05-0028-01-004a