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Philips TG3a CFP Presentation on Alternative High-Rate PHY for WPANs

Philips presents an overview of its proposal for an alternative physical layer for IEEE P802.15.3a, emphasizing its multi-band UWB approach supporting data rates up to 480 Mbps. The presentation outlines features, modulation, parameters, and advantages of the proposed PHY for Wireless Personal Area Networks.

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Philips TG3a CFP Presentation on Alternative High-Rate PHY for WPANs

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Philips TG3a CFP Presentation] Date Submitted: [02 March, 2003] Source: [Charles Razzell, Dagnachew Birru, Bill Redman-White, Stuart Kerry] Company [Philips] Address [1109 McKay Drive, San Jose, CA 95131, California, USA] Voice:[(408) 474-7243], FAX: [(408) 474-5343], E-Mail:[charles.razzell@philips.com] Re: [IEEE P802.15-02/372r8 “IEEE P802.15 Alternate PHY Call For Proposals” dated 17 January, 2003] Abstract: [This presentation gives an overview of the Philips proposal for an alternative physical layer for IEEE P802.15.3a based on a multi-band UWB approach.] Purpose: [Philips requests that the task group considers the merits of the following physical layer proposal and evaluates the content in conjunction with other responses to the Call for Proposals.] 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. Presented by C. Razzell - Philips

  2. Philips TG3a CFP Presentation An alternate high-rate PHY for Wireless Personal Area Networks Presented by C. Razzell - Philips

  3. Outline of Presentation • Main features of this Proposal • Review of Proposed Modulation • Example choice of parameters to obtain required data rates • Advantages of low pulse repetition rate • FEC approach • Pico-net isolation techniques • Transmitter power control • Receiver Implementation Issues • Parallel/Serial dimensioning of receiver structure • Scalability for low cost • Conclusions Presented by C. Razzell - Philips

  4. Main Features of this Proposal • Multi-band Scalable PHY • Compliant with FCC 02-48, UWB Report & Order • Data rates to 480 Mbps and beyond • Spectral Keying Modulation™ offering low pulse rates* • Uses 4-10 sub-bands that occupy 2-6 GHz total bandwidth • Dynamic selection of sub-bands to avoid 802.11a interference • Supports 4 piconets • Additional Features • Flexibility to meet emerging global regulations • Coexists with incumbent and future wireless networks • Low cost, low power implementations are feasible • Meets or Exceeds TG3a Selection Criteria *Modulation scheme originally proposed by General Atomics who own this trademark Presented by C. Razzell - Philips

  5. Multi-Band Modulation(1) pulsed OFDM f6 f5 f4 Information capacity proportional to number of sub-carriers. f3 f2 f1 Peak/mean ratio too high Presented by C. Razzell - Philips

  6. Multi-band Modulation (2) staggered pulses with fixed order f6 f5 Fixed order: information capacity proportional to number of sub-carriers f4 f3 f2 f1 Peak/mean ratio is much reduced! Presented by C. Razzell - Philips

  7. Introduce Sequence Keying Use sequence as information bearing parameter. Information capacity is proportional to # sub-carriers +log2(n!) Presented by C. Razzell - Philips

  8. Spectral Keying™Sequence Keying in addition to PSK 45 Sequence QPSK Use of sequence bits approx. doubles number of bits per pulse of QPSK system when 8 sub-carriers are used. Total 40 35 30 25 # of bits 20 15 10 5 0 1 2 3 4 5 6 7 8 9 10 # of frequencies Presented by C. Razzell - Philips

  9. -6 10 -8 10 -10 10 -12 10 0 1 2 3 4 5 6 7 8 9 10 Coding gain of SK (n=5) Spectral Keying vs. BPSK 0 10 SK(n=5) BPSK -2 10 -4 10 BER Eb/No [dB] Presented by C. Razzell - Philips

  10. Simulated BER Curves 6 sub-bands, 8 sequence bits, 12 phase bits Presented by C. Razzell - Philips

  11. Summary of SK • Use of sequence to carry information significantly increases information per pulse. • This allows the interval between successive pulses to be increased. • Also allows fewer sub-bands to be used for a given pulse rate (implementation advantages). • This increased guard time can be used for ISI reduction and/or possible insertion of time-interleaved piconets. • The modulation remains robust, even with ~4 bits per symbol on each frequency band. Presented by C. Razzell - Philips

  12. Example Parameters for Required PHY Data Rates Presented by C. Razzell - Philips

  13. Example Parameters Continued Presented by C. Razzell - Philips

  14. Impulse response realizations (CM2) 1 Next impulse response starts here (11MHz) 0.5 0 Next impulse response starts here (22MHz) -0.5 -1 -1.5 0 20 40 60 80 100 120 Time (nS) Advantages of low pulse repetition rate Presented by C. Razzell - Philips

  15. Advantages of Low Pulse Repetition Rate High ISI zone CM2 represents NLOS 0-4m CM3 represents NLOS 4-10m Next impulse response starts here (11MHz) Next impulse response starts here (22MHz) Presented by C. Razzell - Philips

  16. Forward Error Correction Approach(based on results from IMEC’s T@MPO core) • Parallel Concatenated Convolutional Turbo Codes • 8-state Recursive Systematic Convolutional Codes • Collision-free interleaving patterns[1] • Parallel SISO units process sub-frames • Early stop criterion minimizes energy usage • Decoding latency of 5ms per block [1] A. Gulietti et al. “Parallel Turbo Code Interleavers; Avoiding collisions in access to storage elements.” Electronics Letters vol. 38 No 5. Presented by C. Razzell - Philips

  17. Channelization for Pico-nets • Propose to use a combination of frequency interleaving and time interleaving } Time division into even and odd time slots 2 Presented by C. Razzell - Philips

  18. Concept for Time Division of Pulse Interval Power decay profile from 2 interleaved pico-nets (CM2) Net 1 0 Net 2 -5 Two 110Mbps piconets are time interleaved with 11MHz pulse rate each. -10 average power (dB) -15 -20 -25 0 10 20 30 40 50 60 70 80 90 delay (ns) Passive scanning (probe) Presented by C. Razzell - Philips

  19. Evaluation of Candidate Sub-pulse Slots by Measuring Preamble Quality Phase bits=1 Phase bits=0 Preamble may be designed to allow MUI to be estimated in all four quadrants of a pulse interval. The “best” slot is chosen for transmission of the immediately following frame. Presented by C. Razzell - Philips

  20. Closed loop power control • An additional use of the pre-amble quality feedback mechanism is to allow for closed power control • Preamble acknowledgement word could include 2 power control and 2 sub-slot selection bits. • Closed loop power control is considered essential for dense deployment scenarios (e.g. multiple laptops in a conference room) • Additional quality information can be gathered during the data-bearing part of the packet to assist with power control and sub-slot selection. Presented by C. Razzell - Philips

  21. Rx - High Performance Implementation Quadrature LOs may be low-spec on-chip oscillators with low area and power. LOs Shared with Tx Path Common front-end; can reduce power with SK duty cycle 3-4 bits ADC helped by AGC per band Presented by C. Razzell - Philips

  22. Rx - Low Power/Cost Implementation Common front-end; can reduce power with SK duty cycle ADC +Rake Rx replaced by analog detector with AGC Saving ~100mW power from ADCs + 3 finger Rake Rx Presented by C. Razzell - Philips

  23. Tx Implementation Low spec LO shared with RX channels Presented by C. Razzell - Philips

  24. Power and Area vs. Data Rate and Implementation Presented by C. Razzell - Philips

  25. Consideration of Serial vs. Parallel Receiver Structures • Since the sequence of frequencies is unknown and can’t be anticipated, parallel frequency-selective branches are needed • However, most of the duplicated circuits are very small on chip (oscillators, mixers). • Receiver branches may need to sample a significant time window • to allow for different propagation delays in different sub-bands under non-LOS conditions • to allow for collection of multipath echoes for RAKE combining Presented by C. Razzell - Philips

  26. Consideration of Serial vs. Parallel Receiver Structures (cont.) • Entirely serial reception of the sequence of tones is likely to cause performance loss in multipath conditions due to sparse sampling of the energy in each sub-band. • Entirely parallel energy collection in the different sub-bands need not be the only alternative • Partial serialization of the Spectral Keying modulation can be used to realize an excellent compromise… Presented by C. Razzell - Philips

  27. 3ns f6 f5 f3 f4 f2 f1 Partial Serialization of SK Modulation f6 f5 f4 18ns 18ns Presented by C. Razzell - Philips

  28. f6 f3 f3 f5 f2 f2 f4 f1 f1  6ns 18ns 6ns 18ns Partial Serialization of SK Modulation • No information loss w.r.t. fully parallel Spectral Keying • Same ML decoding algorithm can be applied • The number of receiver branches can be halved • Further degrees of serialization can be considered Presented by C. Razzell - Philips

  29. Partial Serialization is Compatible with Time-division of Pico-nets f6 f3 Net-2 f5 f2 f4 f1 f3 f6 Net-1 f2 f5 f1 f4 18ns 18ns Presented by C. Razzell - Philips

  30. Comments on Scalability • RAKE combining need not be used. • Low cost receiver implementation possible using analog correlator with single-bit sampling. • Full serialization may be used when the number of sub-bands is low and the pulse repetition interval is sufficiently long (for low cost and low data rate applications). Presented by C. Razzell - Philips

  31. Self-Evaluation against Selection Criteria Presented by C. Razzell - Philips

  32. Conclusions • Proposed SK Modulation provides: • a high order modulation scheme with inherent robustness (coding gain w.r.t. BPSK). • an increased number of bits per pulse leading to a low pulse repetition rate which reduces ISI. • fewer sub-bands for a given pulse repetition rate (cf. QPSK). • energy conservation related to SK’s ability to support low duty cycle. • Pico-net isolation can be achieved in the frequency and time dimensions (2 channels in each dimension). • Transmitter power control is strongly recommended to enable dense deployment scenarios. • Implementations may use a high performance digital receiver, or reduced cost/power versions (scalability). • SK may be used with different degrees of parallel/serial tradeoff thus dividing the number of receiver branches by 2 or more. Presented by C. Razzell - Philips

  33. 802.15.3a Early Merge Work Philips will be cooperating with: • General Atomics • Intel • Discrete Time • Time Domain • Wisair • Focus Enhancements • Samsung • 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. Presented by C. Razzell - Philips

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