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

January 2005. doc.: IEEE 802.15-04/704r1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS). Submission Title: [Staccato UWB PHY Proposal for TG4a] Date Submitted: [January 2005] Revised: []

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

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  1. January 2005 • doc.: IEEE 802.15-04/704r1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS) Submission Title: [Staccato UWB PHY Proposal for TG4a] Date Submitted: [January 2005] Revised: [] Source: [Roberto Aiello, Ph.D., Torbjorn Larsson, Ph.D.] Company [Staccato Communications] E-mail [roberto@staccatocommunications.com] Re: [802.15.4a Call for proposal] Abstract: [This presentation represents Staccato Communication’s proposal for the 802.15.4a PHY standard, based on UWB] Purpose: [Response to WPAN-802.15.4a 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 or organization. The material in this document is subject to change in form and content after further study. The contributor reserves 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.

  2. Staccato CommunicationsUWB PHY Proposal for TG4a Roberto Aiello, Ph.D. Torbjorn Larsson, Ph.D. Staccato Communications r@staccatocommunications.com Roberto Aiello, Staccato Communications

  3. Goals • Good use of UWB unlicensed spectrum • Good system design • Path to low complexity CMOS design • Path to low power consumption • Scalable to future standards • Graceful co-existence with other services • Graceful co-existence with other UWB systems Roberto Aiello, Staccato Communications

  4. Introduction • Staccato is MBOA’s founding member, promoter BOD member • This proposal is based on band limited impulse radio • OFDM is optimal solution for high performance systems • Impulse radio has attractive features for 15.4a applications Roberto Aiello, Staccato Communications

  5. Features • Meets all system requirements • Low signal repetition frequency to reduce ICI/ISI and need for high speed digital circuits (lower power consumption) • “Narrow” UWB bandwidth to reduce complexity • Use of differential encoding on chip level to reduce receiver complexity and provide maximum robustness Roberto Aiello, Staccato Communications

  6. Summary • Band limited UWB system compliant with FCC 02-48, UWB Report & Order • 500MHz bandwidth at -10dB • Two bands centered at 4.752 GHz and 5.252 GHz (MB-OFDM band 4 and 5) • Symbol rates varying from 12.5 kbps to 1.6 Mbps at PHY-SAP • Due to time constraints, this presentation addresses • Modulation scheme, channelization and packet structure • Performance in AWGN • Remaining material will be presented at the next opportunity in March 2005 • Performance in multipath • Implementation feasibility • Self evaluation criteria • Other issues that will emerge from group’s feedback Roberto Aiello, Staccato Communications

  7. Multipath CM8 (Industrial NLOS) PRF = 3.2 MHz Roberto Aiello, Staccato Communications

  8. System Description PRF = 3.2 MHz Roberto Aiello, Staccato Communications

  9. System Description, Continued • Impulse radio combined with direct-sequence spreading • Differential BPSK modulation of chips • A code word covers one BPSK-modulated symbol • Different piconets use different code words • Differential encoding of chips allows the use of differential chip detection in the receiver • Differential detection is carried out separately for each multipath component • Differential combining of multipath components • No need for channel estimation • Simple receiver structure with decent performance Roberto Aiello, Staccato Communications

  10. System Description, Continued • For improved performance, non-coherent symbol detection (with coherent energy integration across one code word) can be used • Symbol detection is carried out separately for each multipath component • Non-coherent combining of multipath components • Still no need for channel estimation • PRF (chip rate): 3.2 MHz • Low enough to avoid interchip interference (ICI) with all 802.15.4a multipath models • High enough to eliminate the need for frequency offset correction (with some performance loss) when differential detection is used • Pulse shape: 3rd-order Butterworth or similar • FEC: 16-state rate-1/2 convolutional code and symbol repetition Roberto Aiello, Staccato Communications

  11. Differential Multipath Combining Roberto Aiello, Staccato Communications

  12. System Parameters PHR = PHY Header; PSDU = PHY Service Data Unit; SFD = Start-of-Frame Delimiter • Length of spreading code in preamble is always 16 • Duty cycle < 100% means that code words of length 16 are transmitted with a space in between • An extra initial chip is added to serve as phase reference for the first chip in the code word • For instance, to achieve a duty cycle of approximately 50%, 17 chips are transmitted followed by a space equivalent to 15 chip periods Roberto Aiello, Staccato Communications

  13. Packet Structure Roberto Aiello, Staccato Communications

  14. Spreading Codes (Length 16) -1    -1     1    -1    -1     1    -1     1    -1    -1    -1     1     1     1     1     1 -1     1    -1     1    -1    -1     1     1    -1    -1    -1    -1     1     1     1     1  -1     1     1    -1     1    -1    -1    -1    -1    -1     1     1     1    -1     1     1 -1    -1    -1    -1    -1     1     1     1     1    -1     1     1    -1     1    -1     1 These code words (c) were found by exhaustive search based on the three following properties: • Low cyclic autocorrelation • Low cyclic cross-correlation between code words c • Low cross-correlation between code words (1,c) and (1,-c) Roberto Aiello, Staccato Communications

  15. Throughput • The length of the data PSDU (payload) is 32 octets. The data rate is 100 kbps (this is X0 in this proposal) • Assumptions (refer to the figure on page 20 in the PHY selection criteria document) • aMinLIFSPeriod = 40 symbol periods • aTurnaroundTime = 12 symbol periods • aUnitBackoffPeriod = 20 symbol periods • Length of ACK PSDU = 5 octets • t_ack is the time between the end of the data frame and the beginning of the ACK frame • worst case, is t_ack = aTurnaroundTime + aUnitBackoffPeriod = 32 • best case, t_ack is t_ack = aTurnaroundTime = 12 Roberto Aiello, Staccato Communications

  16. Receiver Architectures A. Differential chip detection during both acquisition and data demodulation B. Differential chip detection during acquisition and non-coherent symbol detection during data demodulation Roberto Aiello, Staccato Communications

  17. More on Receiver Architectures • In both architectues, acquisition is based on differential detection/combining • Does not require frequency offset correction and therefore leads to shorter preamble (=> less overhead) • Small performance loss at 20 ppm frequency error • If desired, frequency offset estimation can be carried out in parallel with synchronization Architecture A • Differential chip detection for data demodulation • Frequency offset correction may still be applied during PHR and PSDU to improve performance Architecture B. • Non-coherent symbol demodulation for data demodulation • Significant performance improvement, since we are now summing energy coherently across a whole codeword (which for data rates <= 100 kbps is 16 chips long) • Requires frequency offset estimation (during acquisition) and correction (during data demodulation) Roberto Aiello, Staccato Communications

  18. Link Budget Roberto Aiello, Staccato Communications

  19. System Simulation Parameters • Frequency band: 4.752GHz (MB-OFDM band 4) • 10 dB bandwidth: 500 MHz • Transmit power: -16.1 dBm • Transmit/Receive filter: 3rd order Butterworth, corner frequency 180 kHz • A/D converter: 528 MHz, 3 bits • Noise figure: 7 dB • Data rate: 100 kbps • PSDU size: 32 bytes • PRF (chip rate): 3.2 MHz • Length of DS spreading code: 16 • Length of preamble: 48 bits • Length of SFD: 32 bits • Length of PHR: 48 bits • Modulation: DBPSK • Demodulation method: differential detection • No frequency offset Roberto Aiello, Staccato Communications

  20. Spectrum TX Power: -16.1 dBm Roberto Aiello, Staccato Communications

  21. PER vs. Distance in AWGN (100 kbps) Roberto Aiello, Staccato Communications

  22. PER vs. Eb/No (100 kbps) Roberto Aiello, Staccato Communications

  23. PER vs. Received Power (100 kbps) Roberto Aiello, Staccato Communications

  24. Conclusions • UWB band limited system • Meet all system requirements • Low signal repetition frequency to reduce ICI and need for high speed digital circuits (lower power consumption) • “Narrow” UWB bandwidth to reduce complexity • Remaining material will be presented at the next opportunity Roberto Aiello, Staccato Communications

  25. 802.15.4a Early Merge Work Staccato Communications is actively collaborating with others • 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. Roberto Aiello, Staccato Communications

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