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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) PowerPoint Presentation
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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [P802.15 Alt PHY using FM-OFDM] Date Submitted: [3 March, 2003] Source: [Kenneth A. Boehlke] Company [FOCUS Enhancements, Inc.] Address [22867 NW Bennett Road, Hillsboro, OR 97124] Voice:[503 615-7727], FAX: [503 615-4232], E-Mail:[kenb@focusinfo.com] Re: [Call For Proposal: 02372r8P802-15_TG3a-Call-for-Proposal, 03Dec02] Abstract: [P802.15.3a Alternate Physical Proposal Presentation] Purpose: [Document is a Power Point Presentation for discussion at the March 2003 Plenary Meeting] 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. Kenneth A. Boehlke, FOCUS Enhancements

  2. P802.15.3a Alt PHY using FM-OFDM Kenneth A. Boehlke FOCUS Enhancements, Inc. Kenneth A. Boehlke, FOCUS Enhancements

  3. Introduction • A successful UWB implementation must excel in the following areas: • Scalability • Scalable Throughput • Scalable Range • Scalable Complexity • Coexistence • Regulatory • Manufacturability Kenneth A. Boehlke, FOCUS Enhancements

  4. Successful UWB Implementation • Scalable Throughput • 50 Mb/sec to 480 Mb/sec in one implementation • Scalable Range • Multipath delay spread increases with increasing range • Symbol reuse should decrease with range to maintain the ability to separate them • Scalable Complexity • While adhering to each throughput, standard should allow implementation complexity tradeoffs • Scaling performance versus cost • Scaling performance versus power consumption Kenneth A. Boehlke, FOCUS Enhancements

  5. Successful UWB Implementation • Coexistence • Coexist with interferers with minimal performance impact • Programmable capability to maximize performance if no interferer is present • Ability to modify configuration for new coexistence conditions • Regulatory • Accommodate different regulatory standards around the world • Occupied bandwidth, coexistence, and power level parameters should be programmable for a single PHY implementation Kenneth A. Boehlke, FOCUS Enhancements

  6. Successful UWB Implementation • Manufacturability • Analog design should use commonplace building blocks (LNAs, mixers, ADCs, DACs, PLLs, …) that have standard Figure of Merit production tests (NF, IP3, ENOB, ... ) • Process portability by favoring digital over analog complexity thus simplifying shrinks and foundry changes • Implementable in an economical process Kenneth A. Boehlke, FOCUS Enhancements

  7. Our UWB Proposal • Multi-band/Multi-channel using FM-OFDM • One transmitter and one receiver block • Excellent spectral fill • Programmable Coexistence • Band leveling to optimize radiated power • PolyPhase Transmitter and Receiver • Cyclic reuse of transmitter and receiver elements for increased system efficiency • Adjustable minimum instantaneous bandwidth • Excellent Multipath reconstruction Kenneth A. Boehlke, FOCUS Enhancements

  8. Our UWB Proposal • Digital signal processing system approach • Reconfigurable for Worldwide use • Programmable for throughput and range scalability • Avoids component sensitivity • Implementable in CMOS • Manufacturable Kenneth A. Boehlke, FOCUS Enhancements

  9. What is FM-OFDM? • FM-OFDM is sequence of symbols that are spread over frequency and time • The symbol modulation bandwidth exceeds the FCC 500 MHz requirement • The sequence rate is such that the symbols are at minimum orthogonal frequency spacings Kenneth A. Boehlke, FOCUS Enhancements

  10. Why FM-OFDM? • Power Spectral Density is continuous in a band • Symbols are spread and heterodyned to different frequency channels • Symbols are contiguous in frequency and can be overlapped in time if needed • Symbols’ sum yields a rectangular band • Minimum FCC bandwidth is readily met Kenneth A. Boehlke, FOCUS Enhancements

  11. Why FM-OFDM? • The Power Spectral Density is rectangular • Delivers maximum power at all frequencies • Maximizes delivered power to the receiver at the most useful lower frequencies • Free Space loss • Noise Figure Kenneth A. Boehlke, FOCUS Enhancements

  12. Using FM-OFDM at 110 Mbits/sec • Rising slope has 28 8-PSK Symbol sets • Each symbol is 10 nsec long • Transmitter phases operate in parallel to reach 500 MHz minimum bandwidth at all times • Sawtooth cycle time (Pulse Repetition Rate) of 320 nsec • Rate 2/3 FEC across the 8-PSK Symbol sets Kenneth A. Boehlke, FOCUS Enhancements

  13. Occupied Bandwidth at 110 Mbits/sec • Occupied Bandwidth = (Nsymbols+1)*Symbol spacing • Symbol spacing is 100 MHz • Occupied Bandwidth = 2.9 GHz • Lower band edge = 3.4 GHz • Upper band edge = 6.3 GHz Kenneth A. Boehlke, FOCUS Enhancements

  14. Occupied Bandwidth at 110 Mbits/sec • Occupies 3.4 to 6.3 GHz • Scheme is scalable to 10 GHz • 6 GHz design is sufficient to meet all requirements • Implementable in CMOS • Diminishing returns at higher frequencies Kenneth A. Boehlke, FOCUS Enhancements

  15. FM-OFDM and Channel Model 3&4 • FM-OFDM provides Frequency Diversity • With Frequency Diversity, information is transmitted over multiple channels that experience uncorrelated effects • For Frequency Diversity, channel spacing must be greater than the Coherence Bandwidth • Information that is coded (FEC) across multiple channels can be reconstructed • Channel spacing is 100 MHz • CM3 Mean Coherence BW (85% energy) = 24.3 MHz • CM4 Mean Coherence BW (85% energy) = 14.7 MHz Kenneth A. Boehlke, FOCUS Enhancements

  16. FM-OFDM and Channel Model 3&4 • Symbol sequence much longer than Channel Model Impulse Response • Sawtooth cycle time = 320 nsec • CM3 Mean Delay Spread (85% Energy) = 41.2 nsec • CM4 Mean Delay Spread (85% Energy) = 70.0 nsec • Inter-Symbol-Interference (ISI) is not an issue • 320 nsec between Symbol set repeat Kenneth A. Boehlke, FOCUS Enhancements

  17. FM-OFDM Block Diagram • Sawtooth and Symbol Modulations are quantized and stored in a look-up table. • Quadrature DAC converts at 3.2 Gs/sec with 2 levels (+1 or -1) plus zero per transmitter phase • Quadrature DAC is implemented with commonplace 3 GHz CMOS serializers and a Pulse Forming Network (PFN) • Quadrature ADC converts at 300 Ms/sec minimum (P=2) Kenneth A. Boehlke, FOCUS Enhancements

  18. FM-OFDM Spectral Plan • Power Spectral Density repeats at 6.4 GHz intervals • Antenna and coupling network attenuates the low frequency end. • Antenna and PFN Pulse Width/Rise Time attenuates the high frequency end. • Band Leveling circuit adjusts the output power to compensate for slope in 3.4 to 6.3 GHz band. Kenneth A. Boehlke, FOCUS Enhancements

  19. Prototype Symbols • Values for 110 Mbits/sec Data Rate • n = sample index; 0  n  N • m = center frequency index; -14  m  +13 • k = phase index; 0  k  7 • N = quadrature code chip length = 32 • M = total channels in a quadrature sideband = 16 Kenneth A. Boehlke, FOCUS Enhancements

  20. Symbol Quantization • Three possible quantization levels {+1, 0, -1} • Sequence of 32 pulse chips each for I and Q symbol • 8-PSK Convolutional Coding SNR (Eb/N0) • 8-PSK with 2/3 Rate Convolutional Code (K=9) asymptotic performance = 9.6 - 5.75 = 3.9 dB • 8-PSK with 2/3 Rate Convolutional Code (K=9) @ BER of 10^-5 = 5.5 dB Kenneth A. Boehlke, FOCUS Enhancements

  21. Kenneth A. Boehlke, FOCUS Enhancements

  22. Symbol Quantization • Examined 3^32 (1.9x10^15) space for the best 8-PSK Symbol fit. • Best 8-PSK Symbol set fit SNR (Eb/N0) = 13.2 dB • 8-PSK with 2/3 Convolutional Code SNR (Eb/N0) requirement = 5.5 dB • SNR overhead = 13.2 - 5.5 = 7.7 dB • Very little sensitivity degradation • From SNR overhead degradation is 0.7 dB. • Much less including transmitter output and receiver IF filtering Kenneth A. Boehlke, FOCUS Enhancements

  23. Link Budget • Excellent spectral fill over the 3.4 to 6.3 GHz band. • Transmitted power (PT) = -6.9 dBm • Geometric mean frequency (f ’C) = 4.63 GHz • Path Loss @ 1 meter (L1) = 45.8 dB Kenneth A. Boehlke, FOCUS Enhancements

  24. Link Budget • Tx and Rx antenna gain (GT and GR) = 0 dBi • Path loss 10/1 meters (L2) = 20 dB • Received Power (PR) = -72.7 dBm • Throughput (Rb) = 140 Mb/s • Noise Power per Bit (N) = -92.5 dBm • Noise Figure (NF) = 6 dB • Power per Bit (PN) = -86.5 dBm • Minimum Eb/N0 (S) = 5.5 dB • Link Margin + Implementation Loss (M+I) = 8.3 dB Kenneth A. Boehlke, FOCUS Enhancements

  25. Noise Figure Justification • Frequency Range is 6 GHz and below • LNA has a good Noise Figure • Mixers have low conversion loss • T/R Switch has a low insertion loss • No external notch filter requirement • Only T/R Switch loss before the LNA • Fundamental Conversion Frequency Mixer • No harmonic mixing, LMixer 20*log(Harmonic) + 6 • Harmonic = 1; LMixer 6 dB • Steep gain distribution (LNA determines NF) • Distortion dominated by Third Order Intermodulation. • Bandwidth < Octave so no Harmonic Distortion. Kenneth A. Boehlke, FOCUS Enhancements

  26. PolyPhase Receiver • Receiver carrier tracks the transmitter’s carrier and digitizes a frequency band surrounding the carrier • IF and ADC bandwidth determines how many simultaneous channels are digitized at once • A receiver phase is tuned to each channel • The more receiver phases the longer a receiver can dwell at each symbol frequency • Following the symbol reception each receiver phase is reused • Phases roll through the sawtooth carrier in modulo(m,P) pattern • P is the number of receiver phases << number of channels Kenneth A. Boehlke, FOCUS Enhancements

  27. PolyPhase Receiver • FM-OFDM signal is convolved by the channel impulse response (CIR). • The signal is spread in time to a length of the symbol + CIR time. • To get all the Multipath energy the receiver must dwell in each channel for the symbol + CIR time. • Shorter times recover a majority of the energy Kenneth A. Boehlke, FOCUS Enhancements

  28. PolyPhase Receiver • Scalable Multipath Performance by varying the number of receiver phases. • Cost versus performance tradeoff • Power consumption versus performance tradeoff • Technology migration path • Multiple demodulators are implemented with DSP Kenneth A. Boehlke, FOCUS Enhancements

  29. PolyPhase Receiver • Applications that use one receiver phase (P=1) • Control data transfer • Keyboards, mice, and remote controls • Ultra-low cost and power • Limited range and throughput use • Implemented as an FM receiver • Applications that use a small number of receiver phases (P>1) • Data and video transfers • Laptops, printers, cameras, camcorders, peripherals • Lower cost and power • 4 to 10 meter range use (isotropic antenna) Kenneth A. Boehlke, FOCUS Enhancements

  30. PolyPhase Receiver • Applications that use many receiver phases (P>>1) • Long distance data and video transfers • High speed WLAN, Video distribution • Low cost and power • 10 meter or more range use (isotropic antenna) • High throughput rates Kenneth A. Boehlke, FOCUS Enhancements

  31. 802.11a and FM-OFDM Coexistence • Narrow band 802.11a is centered in an unused FM-OFDM band. • Null is tunable by adjusting sample rate and channel number with software. • Adaptable for US, European, Japan, and other National Regulations. Kenneth A. Boehlke, FOCUS Enhancements

  32. Rate and Range Scalability • Ways to increase throughput • Increase the symbol rate • Add additional FM sawteeth • Re-organize the transmitter phases • Combination of both above Kenneth A. Boehlke, FOCUS Enhancements

  33. Rate and Range Scalability Kenneth A. Boehlke, FOCUS Enhancements

  34. Synchronization • Single band synchronization symbols • Strong synchronization with multipath frequency nulls • No PER degradation due to sync loss • 2-ARY Complementary Keying • Strong synchronization with uncoordinated Piconets • Supports multiple access using Code Division • Uncorrelated sync and data symbols Kenneth A. Boehlke, FOCUS Enhancements

  35. Summary • FM-OFDM is a flexible PHY scheme • Scalable • Configurable to worldwide adaptations • Programmable • Supports multiple piconets • FM-OFDM is Manufacturable Kenneth A. Boehlke, FOCUS Enhancements

  36. Scalable • Throughput • 50 to 480 Mbits/sec data rates • Range • Symbols to support 40 meter ranges • Complexity • Supports simple applications • Keyboards, mice, etc. • Supports demanding applications • High rate and long distance data distribution Kenneth A. Boehlke, FOCUS Enhancements

  37. Adaptable Worldwide • Occupied Spectrum • Frequency Bands are programmable • Addresses regulatory differences • Coexistence Nulls • Nulls (when needed) are programmable • Variable Power Levels • Power level of each band is programmable • Band leveling is programmable Kenneth A. Boehlke, FOCUS Enhancements

  38. Manufacturable • Standard Analog Design • Uses blocks available in standard CMOS • Specialized blocks not required • Emphasis on Digital Processing • Process Portability • Low sensitivity to component variability • Benefits from Moore’s Law • Broad implementation options Kenneth A. Boehlke, FOCUS Enhancements

  39. Conclusion • FM-OFDM is a flexible PHY approach • FM-OFDM is a comprehensive PHY scheme • FM-OFDM is manufacturable Kenneth A. Boehlke, FOCUS Enhancements

  40. 802.15.3a Early Merge Work Intel will be cooperating with: Time Domain Discrete Time General Atomics Wisair Philips FOCUS Enhancements Objectives: • “Best” Technical Solution • ONE Solution • Excellent Business Terms • Fast Time To Market We encourage participation by any party who can help us reach our goals. Kenneth A. Boehlke, FOCUS Enhancements