Waveform Modulated Low Rate UWB System - Proposal for 15.4a alt PHY

1. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 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: [Mar., 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. Submission Slide 1 Soo-Young Chang, CSUS

2. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 WAVE FORM MODULATED LOW RATE UWB SYSTEM- Proposal for 15.4a alt PHY- Soo-Young Chang California State University, Sacramento Submission Slide 2 Soo-Young Chang, CSUS

3. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 INTRODUCTION Submission Slide 3 Soo-Young Chang, CSUS

4. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 INTRODUCTION • Use short duration impulses: purely processed in time domain, not in frequency domain • Simple concept: only a few components in TX and RX • 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 waveforms and codes • Excellent co-existence capability due to adaptive frequency band usage – flexible to eliminate forbidden bands (e.g. UNII band) Submission Slide 4 Soo-Young Chang, CSUS

5. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 PHY TASKS (1) • 802.15.4 PAR – Purpose [To provide a standard for ultra low complexity, ultra low cost, ultra low power consumption and low data rate wireless connectivity among inexpensive devices. The raw data rate will be high enough (maximum of 200kbs) to satisfy a set of simple needs such as interactive toys, but scaleable down to the needs of sensor and automation needs (10kbps or below) for wireless communications. • 802.15.4a PAR -- Purpose [To provide a standard for a low complexity, low cost, low power consumption alternate PHY for 802.15.4 (comparable to the goals for 802.15.4). The precision ranging capability will be accurate enough, several centimeters or more, and the range, robustness and mobility improved enough, to satisfy an evolutionary set of industrial and consumer needs for WPAN communications. The project will address the requirements to support sensor, control, logistic and peripheral networks in multiple compliant co-located systems and also coexistence (18b).] • 802.15.4 PAR – Scope [This project will define the PHY and MAC specifications for low data rate wireless connectivity with fixed, portable and moving devices with no battery or very limited battery consumption requirements typically operating in the Personal Operating Space (POS) of 10 meters … • 802.15.4a PAR – Scope [This project will define an alternative PHY clause for a data communication standard with precision ranging, extended range, enhanced robustness and mobility amendment to standard 802.15.4 (18a).] Submission Slide 5 Soo-Young Chang, CSUS

6. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 PHY TASKS (2) • Specified in existing15.4 standard • Activation and deactivation of the radio transceiver • ED within the current channel • LQI for received packets • CCA for CSMA-CA • Channel frequency selection • Data transmission and reception • Range • typical indoor range may be 10 to 30 m • maximum outdoor range may be several km !!! * ED: energy detection * LQI: link quality indication * CCA: clear channel assessment Submission Slide 6 Soo-Young Chang, CSUS

7. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 PLAUSIBLE MYTHS • Myth 1 • ‘Low rate needs less power consumption.’ • With high rates, low power consumption can be achieved. • Key issue is the amount of information delivered and power consumption is mainly related to transmission time and processing time. • 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 simple hardware and provide full flexibility and adaptivity. • As the processing power increases and technologies advance, full digital processing is the trend. • 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 without using power amplifiers. • 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 realized in the near future and considered for future applications. • Moore’s law says that processing power increases double every 18 months: cost amd complexity can be decreased with the same rate. Submission Slide 7 Soo-Young Chang, CSUS

8. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 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: more bandwidth means more transmitted power • 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 higher frequency signal 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 ???: power consumption is mainly related to processing time  New waveform is needed to fit exactly to frequency mask Submission Slide 8 Soo-Young Chang, CSUS

9. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 CONSIDERATIONS FOR LOW RATE UWB (2) • Data rate • In the technical requirements, “low rate” is suggested with expectation to reduce power consumption and complexity/cost • Power consumption is mainly proportional to the time duration of signal transmission and processing • No need to reduce data rates if higher rates possible with almost the same cost/efforts • With higher data rates, less probability of conflict with other transmissions for random multiple access methods like CSMA and higher success rate with acknowledgements • More pulses may be transmitted for the same information with higher rates: higher robustness and more redundancy can be achieved: more flexibility can be provided • 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 rates and lower cost is inevitable. Submission Slide 9 Soo-Young Chang, CSUS

10. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 CONSIDERATIONS FOR LOW RATE UWB (3) • Full digital processing • Provide full flexibility for any change in signal environments, system concepts and requirements • A variety of complex digital modulation schemes and any complicated system concepts can be accommodated • Eliminate the cost and complexity of a down conversion stage at receiver without using oscillators (or crystals) • Sophisticated digital signal processing technologies needed including high speed ADCs and DACs with sampling rate > 1 Gsamples/sec • Need to devise new signal processing implementations which may need new technology Submission Slide 10 Soo-Young Chang, CSUS

11. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 SYSTEM DESCRIPTION Submission Slide 11 Soo-Young Chang, CSUS

12. Modulation Source coding Channel coding (FEC) ARQ not considered Interleaving Pulse generation Antenna Multiple access Synchronization LNA accommodate ultra wideband Message relaying Simultaneously operated piconets (SOP) Localization function Transmit only device Detection • doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 KEY CONSIDERATIONS Submission Slide 12 Soo-Young Chang, CSUS

13. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 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 any forbidden bands • With FCC mask, 3.1GHz to 10.6 GHz full frequency band can be used to enjoy more transmitted power  3.8 dB more power used than Gaussian pulse’s case with the same frequency band  3.8 dB more margin for link budget Submission Slide 13 Soo-Young Chang, CSUS

14. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 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: base waveform group 2 group 3 group 4 group 1 f 3.1 GHz 10.6 GHz subband 2 subband 3 subband 4 subband 1 f base waveform w23 w24 w21 w22 * If some bands should be abandoned, this subbamd should be a little bit smaller – for example the case that UNII band is excluded. Submission Slide 14 Soo-Young Chang, CSUS

15. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 PULSE WAVEFORM Submission Slide 15 Soo-Young Chang, CSUS

16. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 PULSE WAVEFORM OF SUBBAND • Pulse waveform shape • Mathematical derivation/expression • Shape: duration: 9 ns • Spectrum: almost flat throughout the whole band • How can pulses be generated • Digital way? Overlapped with various delays  can be generated with relatively lower sampling rate DACs • 90 samples/waveform: • 16 waveforms/group for binary representation 81 waveforms/group for ternary representation • 1440 or 7290 sample information stored in ROM per group  1.44 or 7.29 Kbytes ROM needed to store waveform information if 8 bits/sample is adopted • Generate waveforms using DACs which have 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 Submission Slide 16 Soo-Young Chang, CSUS

17. 0.2 2 0 0.15 amplitude in dB -2 0.1 amplitude -4 0.05 -6 0 -8 -0.05 -10 -0.1 -12 -0.15 -14 -0.2 -16 -10 -8 -6 -4 -2 0 2 4 6 8 10 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 frequency time • doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 TYPICAL PULSE WAVEFORM (BASE WAVEFORM) • The above base waveform for bandwidth of 3.8 GHz, 20 samples/ns • For each subband, there is one waveform which has flat spectrum almost throughout the subbnad as shown in the above. • Group i has four base waveforms: wi1, wi2, wi3 , and wi4 • Group i has 16 waveforms: mi1, mi2, mi3, . . . , mi16 mij,=a* wi1 +b* wi2 +c* wi3 +d* wi4 where a, b, c, and d are determined by modulation method applied Submission Slide 17 Soo-Young Chang, CSUS

18. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 TYPICAL PULSE WAVEFORM (BASE WAVEFORM) • The above base waveform for bandwidth of 0.469 GHz, 10 samples/ns • For each subband, there is one waveform which has flat spectrum as shown in the above. • Group i has four base waveforms: wi1, wi2, wi3 , and wi4 • Group i has 16 waveforms: mi1, mi2, mi3, . . . , mi16 mij,=a* wi1 +b* wi2 +c* wi3 +d* wi4 where a, b, c, and d are determined by modulation method applied Submission Slide 18 Soo-Young Chang, CSUS

19. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 SPECTRAL FLATNESS vs NO OF SAMPLES/WAVEFORM • With the same waveform, spectral flatness depends on the number of samples for each waveform • More samples makes the spectrum flatter: flatter inside the band and more suppression outside the band • Power ratio=power with perfectly flat spectrum / power with less perfectly flat spectrum • For the cases • Bandwidth = 469 MHz • Pulse width = 9 ns • No. bits/sample = 8 • No. samples/waveform = 50, 90, 140, 180, 280, 400 Flatness vs no of samples for Subband 1, group 1 Submission Slide 19 Soo-Young Chang, CSUS

20. 2 1.8 1.6 1.4 1.2 amplitude 1 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5 6 7 8 9 10 Frequency( GHz.) • doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 BASE WAVEFORMS FOR ONE GROUP • For four subbands – assuming each subband has 1 GHz BW • If smaller BW, larger pulse width + + + t (ns) 0 4 Submission Slide 20 Soo-Young Chang, CSUS

21. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 BASE WAVEFORMS FOR ONE GROUP • For four subbands - for smaller BW, larger pulse width For BW of a subbnad in Group 1=469 MHz subband 1 subband 2 subband 3 subband 4 Submission Slide 21 Soo-Young Chang, CSUS

22. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 ORTHOGONALITY OF WAVEFORMS • For each subband, one base waveform exists • 16 base waveforms throughout whole band (four groups): w11(t), w12(t), w13(t), w14(t), w21(t), . . . . , w43(t), w44(t) • Each waveform is almost orthogonal to each other or perfectly orthogonal after de-emphasis at RX • Each group has • 16 waveforms for binary base waveform modulation (OOK or BPSK) or • 81 waveforms for ternary base waveform modulation (OOK+BPSK) • These waveforms are orthogonal to each other after de-emphasis at RX • m1,1=0, m1,2= w1, m1,3= w2, . . . . , m4,16= w13+ w14+ w15+ w16 with OOK • m1,1= -w1 -w2 –w3 –w4, . . . . , m4,16= w13+ w14+ w15+ w16 with BPSK Submission Slide 22 Soo-Young Chang, CSUS

23. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 CORRELATIONS BETWEEN WAVEFORMS • Correlation where : kth sample of ith basewaveform of a group for N samples/waveform • 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, de-emphasis can be used to make pure sinusoidal for a period • mij*mij=(a* wi1 +b* wi2 +c* wi3 +d* wi4 )(a* wi1 +b* wi2+c* wi3 +d* wi4) where mij is the waveform transmitted and mij is the waveform generated at RX after de-emphasis • After integration for a one waveform duration, only autocorrelation terms remain • Orthogonality can hold at RX during detection for matched waveforms • What is the best sampling frequency such that orthogonality can be achievable? • Less than 8 bits/sample will be enough for orthogonality evaluation? – need to verify • “Power consumption of ADCs goes up exponentially with resolution”, EE times, Jan 17, 2005, pp 49 Submission Slide 23 Soo-Young Chang, CSUS

24. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 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 Nsampled sinusoidal signal segments exact orthogonality holds only for the hamonics of the sampling rate-divided-by-N , 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 Submission Slide 24 Soo-Young Chang, CSUS

25. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 CORRELATIONS BETWEEN TWO BASE WAVEFORMS • # of samples = 180 # of samples = 90 • Correlation ratio = autocorrelation/crosscorrelation Submission Slide 25 Soo-Young Chang, CSUS

26. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MODULATION Submission Slide 26 Soo-Young Chang, CSUS

27. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 POSSIBLE MODULATIONSFOR EACH WAVEFORM • Each waveform can be modulated by using the following modulation schemes depending on required data rates, system complexity, detection method, etc Submission Slide 27 Soo-Young Chang, CSUS

28. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MODULATION/MULTIPLE ACCESS (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 needed to be transmitted  totally related to transmit time • for UWB, BW>500MHz or fractional BW>20% of fc short duration pulses • one possibility to increase energy by using multiple pulses for one bit (or symbol) • need to use more power under frequency mask to have higher power • power constrained with frequency mask for LR-WPAN case • new waveform needed to fit the frequency mask 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: but for lower rate, less important  more room for flexibility for LR-WPAN • However, as bit duration increases, more power consumption may be required Submission Slide 28 Soo-Young Chang, CSUS

29. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 NO OF COMBINATIONS (BINARY MOD) • For each subband, one base waveform exists • 16 base waveforms throughout whole band: w11(t), w12(t), w13(t), w14(t), w21(t), . . . . , w43(t), w44(t) • Each waveform is almost orthogonal to each other • For one symbol duration • 16 waveforms per group: Each group has 16 waveforms • m1,1=0, m1,2= w1, m1,3= w2, . . . . , m4,16= w13+ w14+ w15+ w16 for OOK • m1,1= -w1- w2- w3- w4, . . . . . , m4,16= w13+ w14+ w15+ w16 for BPSK 16 symbols in frequency domain because of 16 frequency bins • For n durations in time domain  to provide MA + FEC • 16*n, 8*n, 4*n, 2*n, and 1*n symbols • n can be specified for each type of devices/communications/applications Submission Slide 29 Soo-Young Chang, CSUS

30. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 WAVEFORMS FOR EACH GROUP(BINARY MOD) group 2 group 3 group 4 group 1 f 3.1 GHz 10.6 GHz m1,1(t) m1,1(t) m1,1(t) m1,1(t) m1,1(t) m1,1(t) m1,1(t) m2,1(t) m3,1(t) m1,1(t) m1,1(t) m1,1(t) m4,1(t) m1,2(t) m1,2(t) m1,2(t) m1,2(t) m2,2(t) m1,2(t) m1,2(t) m1,2(t) m1,2(t) m1,2(t) m1,2(t) m3,2(t) m4,2(t) m1,16(t) m1,16(t) m1,16(t) m1,16(t) m1,16(t) m2,16(t) m1,16(t) m1,16(t) m1,16(t) m1,16(t) m1,16(t) m3,16(t) m4,16(t) Submission Slide 30 Soo-Young Chang, CSUS

31. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 SUBGROUPS FOR EACH GROUP(BINARY MOD) group 2 group 3 group 4 group 1 f 3.1 GHz 10.6 GHz SG1 SG2 SG3 SG4 Submission Slide 31 Soo-Young Chang, CSUS

32. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MODULATION PROPOSED (1) • 4 waveforms of a subgroup are mapped to 2 bit (quaternary) information ex) m1,1(t)  00 m1,6(t)  01 m1,11(t)  10 m1,16(t)  11 • Each user sends information using one subgroup of each group  in one time duration 8 bit information is delivered for whole band • Each waveform is modulated by OOK (+1,0) Submission Slide 32 Soo-Young Chang, CSUS

33. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 EXAMPLES OF WAVEFORMS (OOK) m1,2(t) m1,6(t) m1,16(t) Submission Slide 33 Soo-Young Chang, CSUS

34. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MODULATION PROPOSED (2) • 4 waveforms of a subgroup are mapped to 2 bit (quaternary) information ex) m1,1(t)  00 m1,6(t)  01 m1,11(t)  10 m1,16(t)  11 • Each user sends information using one subgroup of each group  in one time duration 8 bit information is delivered for whole band • Each waveform is modulated by BPSK (+1, -1) Submission Slide 34 Soo-Young Chang, CSUS

35. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 EXAMPLES OF WAVEFORMS (BPSK) m1,1(t) m1,11(t) m1,16(t) Submission Slide 35 Soo-Young Chang, CSUS

36. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MODULATION PROPOSED (3) • 16 waveforms of a group are mapped to 4 bit information ex) mi,1(t)  0000 mi,6(t)  0101 mi,11(t)  1010 mi,16(t)  1111 • Each user send information using one group  in one time duration 4 bit information is delivered • Each waveform is modulated by OOK (+1,0) Submission Slide 36 Soo-Young Chang, CSUS

37. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 WAVEFORM FOR DATA STREAM (OOK) FOR MODULATION PROPOSED (3) Submission Slide 37 Soo-Young Chang, CSUS

38. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 NO OF COMBINATIONS (TERNARY MOD) • For each subband, one base waveform exists • 16 base waveforms throughout whole band: w11(t), w12(t), w13(t), w14(t), w21(t), . . . . , w43(t), w44(t) • Each waveform is almost orthogonal to each other • For one symbol duration • 81 waveforms per group: 64 waveforms selected out of 81 waveforms per group • m1,1=0, m1,2= w1, m1,3= w2, . . . . , m4,16= w13+ w14+ w15+ w16for OOK • m1,1= -w1- w2- w3- w4, . . . . , m4,16= w13+ w14+ w15+ w16 for BPSK  16 symbols in frequency domain because of 16 frequency bins • For n durations in time domain  to provide MA + FEC • 64*n , 32*n , 16*n, 8*n, 4*n, 2*n, and 1*n symbols • n can be specified for each type of devices/communications/applications Submission Slide 38 Soo-Young Chang, CSUS

39. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 WAVEFORMS FOR EACH GROUP(TERNARY MOD) group 2 group 3 group 4 group 1 f 3.1 GHz 10.6 GHz m1,1(t) m1,1(t) m1,1(t) m1,1(t) m2,1(t) m1,1(t) m1,1(t) m1,1(t) m1,1(t) m1,1(t) m1,1(t) m3,1(t) m4,1(t) m1,2(t) m1,2(t) m1,2(t) m1,2(t) m1,2(t) m2,2(t) m1,2(t) m1,2(t) m1,2(t) m3,2(t) m1,2(t) m1,2(t) m4,2(t) m1,64(t) m2,64(t) m3,64(t) m4,64(t) Submission Slide 39 Soo-Young Chang, CSUS

40. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 DATA RATES WITH 100% OVERHEAD • 1 Mbps max with 100% overhead Tb = 1/(2 Mbps) = 500 ns • Pulse width = 9 ns  Duty cycle < 2 % 500 ns 500 ns Submission Slide 40 Soo-Young Chang, CSUS

41. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MULTIPLE ACCESS (MA) Submission Slide 41 Soo-Young Chang, CSUS

42. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MULTIPLE ACCESS (MA) • Possible MAs considered • Frequency hopping (FH) among subbands/groups • Not efficient because of uncertainty of FCC’s ruling on FH so far and less usage of power • TDMA • Less time efficient • More difficult to synchronize • Direct-sequence (DS) CDMA • Less time efficient and more complex to process • New MA needed? f Group 4 Group 3 Group 2 Group 1 t1 t2 t3 t4 t5 t 16 frequency bins time domain bins Submission Slide 42 Soo-Young Chang, CSUS

43. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MAPPING FREQUENCY BINS TO WALSH ENCODED SYMBOLS Submission Slide 43 Soo-Young Chang, CSUS

44. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MULTIPLE ACCESS (A) • An 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 • Hamming distances between two piconets codes is 4. • For each frequency bin waveform, BPSK is applied Submission Slide 44 Soo-Young Chang, CSUS

45. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 MULTIPLE ACCESS (B) • An 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 • 64 SOPs case • For one user, two Walsh 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 • Hamming distances between two piconets codes are 4 and 8. • For each frequency bin waveform, BPSK is applied Submission Slide 45 Soo-Young Chang, CSUS

46. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 IMPLEMENTATION Submission Slide 46 Soo-Young Chang, CSUS

47. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 TRANSMITTER STRUCTURE • Simple structure with impulse radio concept • FEC encoder • Interleaver • Pulse generator • Modulator • Antenna antenna This part can be realized using digital processing Data in Data manipulator modulator Source coding Channel coding interleaving Pulse generator Submission Slide 47 Soo-Young Chang, CSUS

48. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 TRANSMITTER BLOCK DIAGRAM ROM, group 2 S/P converter data manipulator input data encoding interleaving encryption ROM, group 1 DAC waveform transformer DAC waveform transformer ROM, group 3 DAC waveform transformer ROM, group 4 DAC waveform transformer Submission Slide 48 Soo-Young Chang, CSUS

49. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 RECEIVER STRUCTURE • Simple receiver structure • Antenna - Pulse generator • LNA - Location processor • Demodulator • Data detector • De-interleaver • Channel decoder • Synchronizer location Synch Information retriever Pulse generator demodulator detector Data De-manipulator Data out antenna LNA Submission Slide 49 Soo-Young Chang, CSUS

50. doc.: IEEE 802.15-05-0028-04-004a Mar. 2005 RECEIVING BLOCK received signal correlation pulse generator Time correlator concept ROM waveform conditioner ADC correlator correlation LNA Submission Slide 50 Soo-Young Chang, CSUS