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: [DS-UWB Proposal Update] Date Submitted: [May 2004] Source: [Reed Fisher(1), Ryuji Kohno(2), Hiroyo Ogawa(2), Honggang Zhang(2), Kenichi Takizawa(2)] Company [ (1) Oki Industry Co.,Inc.,(2)National Institute of Information and Communications Technology (NICT) & NICT-UWB Consortium ]Connector’s  Address [(1)2415E. Maddox Rd., Buford, GA 30519,USA, (2)3-4, Hikarino-oka, Yokosuka, 239-0847, Japan] Voice:[(1)+1-770-271-0529, (2)+81-468-47-5101], FAX: [(2)+81-468-47-5431], E-Mail:[(1)reedfisher@juno.com, (2)kohno@crl.go.jp, honggang@crl.go.jp, takizawa@crl.go.jp ] Source: [Michael Mc Laughlin] Company [decaWave, Ltd.] Voice:[+353-1-295-4937], FAX: [-], E-Mail:[michael@decawave.com] Source: [Matt Welborn] Company [Freescale Semiconductor, Inc] Address [8133 Leesburg Pike Vienna, VA USA] Voice:[703-269-3000], E-Mail:[matt.welborn@freescale.com] Re: [] Abstract: [Technical update on DS-UWB (Merger #2) Proposal] Purpose: [Provide technical information to the TG3a voters regarding DS-UWB (Merger #2) Proposal] 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. Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

2. Outline • DS-UWB Overview • Complexity • Performance • Scalability of UWB implementations • CSM for coexistence and interoperability • Interference issues Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

3. Overview of DS-UWB Proposal • Support for much higher data rates • BPSK modulation using variable length spreading codes • At same time, much lower complexity and power consumption • Essential for mobile & handheld applications • Digital complexity is 1/3 of previous approaches, yet provides good performance at long range and high rates at short range • Harmonization & interoperability with MB-OFDM through a Common Signaling Mode (CSM) • A single multi-mode PHY with both DS-UWB and MB-OFDM • Best characteristics of both approaches with most flexibility Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

4. Advantages of the DS-UWB Solution • DS-UWB is not burdened with the multiple interference issues that continue to plague the MB-OFDM proposal • DS-UWB is shown to have equal or better performance to MB-OFDM in all modes and multipath conditions – for a fraction of the complexity & power • Increases options for innovation and regulatory flexibility to better address all applications and markets • Our vision: A single PHY with multiple modes to provide a complete solution for TG3a • Base mode that is required in all devices, used for control signaling: “CSM” for beacons and control signaling • Higher rate modes also required to support 110 & 200+ Mbps: • Compliant device can implement either DS-UWB or MB-OFDM (or both) Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

5. DS-UWB Operating Bands & SOP Low Band High Band • Each piconet operates in one of two bands • Low band (below U-NII, 3.1 to 4.9 GHz) • High band (optional, above U-NII, 6.2 to 9.7 GHz) • Support for multiple piconets • Classic spread spectrum approach • Acquisition uses unique length-24 spreading codes • Chipping rate offsets to minimize cross-correlation 3 4 5 6 7 8 9 10 11 3 4 5 6 7 8 9 10 11 GHz GHz Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

6. DS-UWB Signal Generation Input Data Scrambler K=6 FEC Encoder Conv. Bit Interleaver Bit-to-Code Mapping Pulse Shaping Center Frequency Gray or Natural mapping K=4 FEC Encoder 4-BOK Mapper Transmitter blocks required to support optional modes • Data scrambler using 15-bit LFSR (same as 802.15.3) • Constraint-length k=6 convolutional code • K=4 encoder can be used for lower complexity at high rates or to support iterative decoding for enhanced performance (e.g. CIDD) • Convolutional bit interleaver protects against burst errors • Variable length codes provide scalable data rates using BPSK • Support for optional 4-BOK modes with little added complexity Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

7. Data Rates Supported by DS-UWB Similar Modes defined for high band Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

8. Digital DS-UWB Receiver Architecture • Architecture assumptions • Front-end filter + LNA • I&Q sampling using 3-bit ADCs • 16-finger rake (at 110 Mbps) with 3-bit complex rake taps • Decision feedback equalizer at symbol rate • Viterbi decoder for k=6 convolutional code p cos ( 2 ) f t c Pre-Select I Filter LPF GA/ VGA ADC 1326 MHz, 3-bit ADC DFE, De- Interleave & FEC Decode Synch. & Rake LNA Q LPF GA/ VGA ADC 1326 MHz, 3-bit ADC p sin ( 2 ) f t c Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

9. Interference Issues (1) • Hopped versus non-hopped signal characteristics • ITS and FCC studies are underway • Goal is to see if interference characteristics of MB-OFDM are acceptable for certification (using DS-UWB/noise/IR for comparison) • Use of PN-modulation to meet 500 MHz BW • Recent statements by NTIA emphasize importance of minimum • Desire is to ensure protection for restricted bands • DS-UWB bandwidth is determined by pulse shape and pulse modulation • Spectrum exceeds 1500 MHz • MB-OFDM bandwidth for data and pilot tones is 466 MHz, guard tones are used to increase bandwidth to 507 MHz • Guard tones “carry no useful information”, only to meet BW req’t. • See authors statements in 802.15-03/267r1 (July 2003, page 12) Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

10. Compliance with 500 MHz Minimum Bandwidth DS-UWB Symbol Bandwidth (no hopping) Bandwidth of DS-UWB > 1500 MHz DS-UWB uses no guard tones, signal always fills >> 500 MHz minimum bandwidth with useful signal energy Bandwidth without Guard Tones = 466 MHz Total of 40 MHz (per hop) is filled with noise emissions in order to meet bandwidth requirements Bandwidth with Guard Tones = 507.4 MHz MB-OFDM Symbol Bandwidth (on each hop) Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

11. Interference Issues (2) • Spectral flexibility to support a potential for enhanced coexistence • DS-UWB can use pulse shaping to modify spectrum • Transparent to receiver, requires no coordination • Dynamic or static using a number of techniques (such as SSA) • Applies to both acquisition preamble AND payload • MB-OFDM proposes dynamically turning on/off bands and tones • Requires coordination between transmitter and receiver • Does not account for PHY preamble which uses a fixed time sample sequence and cannot support notching like OFDM • For medium-to-short packets, preamble can be >50% of energy PHY Preamble Headers Variable length payload Time Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

12. Spectral Notching for DS-UWB and MB-OFDM DS-UWB Notched Spectrum Notch is present in signal spectrum of PREAMBLE based on pulse shaping Notch ALSO present in signal spectrum of payload based on the same pulse shaping MB-OFDM “Notched” Spectrum Spectrum of PREAMBLE is not flexible – cannot be changed by turning off tones Notch is present ONLY in payload portion of signal if specific OFDM tones are nulled Spectrum of payload Spectrum of PREAMBLE Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

13. What can be done? • The simplicity of the MB-OFDM approach was that frequency domain filtering (nulling tones) was simple and low cost • Now we find that we need to generate a different acquisition sequence for each desired tone configuration • This is the same as generating a time-domain pulse shape with arbitrary notches (like SSA) • No simulation results showing • How deep can the notches be made (dB)? • What are the DAC quantization effects? • How does this affect acquisition performance? Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

14. Relative Complexity • Gate counts are drawn based on estimates and methodology presented by MB-OFDM proposal team • Clock speeds are normalized to 85.5 MHz for comparison Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

15. Multipath Performance for 110 Mbps Simulation Includes: 16 finger rake with coefficients quantized to 3-bits 3-bit A/D (I and Q channels) RRC pulse shaping DFE trained in < 5us in noisy channel (12 Taps) Front-end filter for Tx/Rx + 6.6 dB Noise Figure Packet loss due to acquisition failure Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

16. Multipath Performance for 220 Mbps Simulation Includes: 8 finger (16 finger) rake with coefficients quantized to 3-bits 3-bit A/D (I and Q channels) RRC pulse shaping DFE trained in < 5us in noisy channel (12 Taps/24 Taps) Front-end filter for Tx/Rx + 6.6 dB Noise Figure Packet loss due to acquisition failure AWGN Range @220 Mbps = 16.2 m Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

17. Multipath Performance for 500 Mbps Simulation Includes: 16 finger rake with coefficients quantized to 3-bits 3-bit A/D (I and Q channels) RRC pulse shaping DFE trained in < 5us in noisy channel Front-end filter for Tx/Rx + 6.6 dB Noise Figure Packet loss due to acquisition failure Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

18. AWGN SOP Distance Ratios • AWGN distances for low band • High band ratios expected to be lower • Operates with 2x bandwidth, so 3 dB more processing gain Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

19. Multipath SOP Distance Ratios Test Transmitter: Channels 1-5 Single Interferer: Channels 6-10 Second Interferer: Channel 99 Third Interferer: Channel 100 • High band ratios expected to be lower (3 dB more processing gain) Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

20. Scalability • Baseline devices support 110-200+ Mbps operation • MB-OFDM device • Reasonable performance in CM1-CM4 channels • Complexity/power consumption as reported by MB-OFDM team • DS-UWB device • Less than half the digital complexity of an MB-OFDM receiver • Equal or better performance than MB-OFDM in essentially every case • What about: • Scalability to higher data rate applications • Scalability to low power applications • Scalability to different multipath conditions Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

21. High Data Rate Applications • Critical for cable replacement applications such as wireless USB (480 Mbps) and IEEE 1394 (400 Mbps) • High rate device supporting 480+ Mbps • DS-UWB device uses shorter codes (L=2, symbol rate 660 MHz) • Uses same ADC rate & bit width (3 bits) and rake tap bit widths • Rake: use fewer taps at a higher rate or same taps with extra gates • Viterbi decoder complexity is ~2x the baseline k=6 decoder • Can operate at 660 Mbps without Viterbi decoder for super low power • MB-OFDM device • 5-bit ADCs required for operation at 480 Mbps • Increased internal (e.g. FFT, MRC, etc) processing bit widths • Viterbi decoder complexity is ~2x the baseline k=7 decoder (~4x k=6) • Increased power consumption for ALL modes (55, 110, 200, etc.) results when ADC/FFT bit width is increased Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

22. Low Power Applications • Critical for handheld (battery operated) devices that need high rates • Streaming or file transfer applications: memory, media players, etc. • Goal is lowest power consumption and highest possible data rates in order to minimize session times for file transfers • Proposal support for scaling to lower power applications • DS-UWB device • Has very simple transmitter implementation, no DAC or IFFT required • Receiver can gracefully trade-off performance for lower complexity • Can operate at 660 Mbps without Viterbi decoder for super low power • Also can scale to data rates of 1000+ Mbps using L=1 (pure BPSK) or 4-BOK with L=2 at correspondingly shorter ranges (~2 meters) • MB-OFDM device • Device supporting 480 Mbps has higher complexity & power consumption • MB-OFDM can reduce ADC to 3 bits with corresponding performance loss • It is not clear how to scale MB-OFDM to >480 Mbps without resorting to higher-order modulation such as 16-QAM or 16-PSK • Would result in significant loss in modulation efficiency and complexity increase Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

23. Scalability to Varying Multipath Conditions • Critical for handheld (battery operated) devices • Support operation in severe channel conditions, but also… • Ability to use less processing (& battery power) in less severe environments • Multipath conditions determine the processing required for acceptable performance • Collection of time-dispersed signal energy (using either FFT or rake processing) • Forward error correction decoding & Signal equalization • Poor: receiver always operates using worst-case assumptions for multipath • Performs far more processing than necessary when conditions are less severe • Likely unable to provide low-power operation at high data rates (500-1000+ Mbps) • DS-UWB device • Energy capture (rake) and equalization are performed at symbol rate • Processing in receiver can be scaled to match existing multipath conditions • MB-OFDM device • Always requires full FFT computation – regardless of multipath conditions • Channel fading has Rayleigh distribution – even in very short channels • CP length is chosen at design time, fixed at 60 ns, regardless of actual multipath Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

24. The Common Signaling Mode:What Is The Goal? • A common signaling mode (CSM) arbitrates between multiple UWB PHYs • Multiple UWB PHYs will exist in the world • DS-UWB & MB-OFDM are first examples • We need an “etiquette” to manage peaceful coexistence between the different UWB PHYs – a CSM does this • Planned cooperation (i.e. CSM) gives far better QoS and throughput than allowing un-coordinated operation and interference • CSM improves the case for international regulatory approval • CSM provides flexibility/extensibility within the IEEE standard • Allows future growth & scalability • Provides options to meet diverse application needs • Enables interoperability and controls interference Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

25. What Does CSM Look Like?One of the MB-OFDM bands! Proposed Common Signaling Mode Band (500+ MHz bandwidth) 9-cycles per BPSK “chip” DS-UWB Low Band Pulse Shape (RRC) 3-cycles per BPSK “chip” 3978 Frequency (MHz) 3100 5100 MB-OFDM (3-band) Theoretical Spectrum Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

26. CSM Specifics • We have designed a specific waveform for the CSM • BPSK modulation for simple and reliable performance • Length 24 spreading codes using 442 MHz chip rate • Harmonically related center frequency of 3978 MHz • Rate ½ convolutional code with k=6 • Provides 9.2 Mbps throughput (can use L=12 codes for 18.4 Mbps) • It allows co-existence and interoperability between DS-UWB and MB-OFDM devices • Prevents coexistence problems for multiple different UWB PHYs • Provides interoperability in a shared piconet environment • CSM supports the 802.15.3 MAC • Achieves desired 10 Mbps data rates and robust performance • Negligible impact on piconet throughput (beacons are <1%) • Requires very low additional cost/complexity • Almost no additional complexity for either MB-OFDM or DS-UWB Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

27. Conclusions • DS-UWB is shown to have equal or better performance to MB-OFDM in all modes and multipath conditions – for a fraction of the complexity & power • DS-UWB is not burdened with the multiple interference issues that continue to plague the MB-OFDM proposal • Our vision: A single PHY with multiple modes to provide a complete solution for TG3a • Base mode that is required in all devices, used for control signaling: “CSM” for beacons and control signaling • Higher rate modes also required to support 110 & 200+ Mbps: • Compliant device can implement either DS-UWB or MB-OFDM (or both) • Increases options for innovation and regulatory flexibility to better address all applications and markets Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

28. Back-up slides Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

29. NTIA Comments on Using Noise to meet FCC 500 MHz BW Requirement • NTIA comments specifically on the possibility that manufacturer would intentionally add noise to a signal in order to meet the minimum FCC UBW 500 MHz bandwidth requirements: “Furthermore, the intentional addition of unnecessary noise to a signal would violate the Commission’s long-standing rules that devices be constructed in accordance with good engineering design and manufacturing practice.” • And: • “It is NTIA’s opinion that a device where noise is intentionally injected into the signal should never be certified by the Commission.” • Source: NTIA Comments (UWB FNPRM) filed January 16, 2004 available at http://www.ntia.doc.gov/reports.html Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

30. FCC Rules Regarding Unnecessary Emissions • FCC Rules in 47 CFR Part 15 to which NTIA refers: “§ 15.15 General technical requirements. (a) An intentional or unintentional radiator shall be constructed in accordance with good engineering design and manufacturing practice. Emanations from the device shall be suppressed as much as practicable, but in no case shall the emanations exceed the levels specified in these rules.” Kohno NICT, Welborn Freescale, Mc Laughlin decaWave