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

January 2005. doc.: IEEE 802.15-04/xxxr0. 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/xxxr0 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 • Meet all system requirements • Low signal repetition frequency to reduce ISI and need for high speed digital circuits (lower power consumption) • “Narrow” UWB bandwidth to reduce complexity Roberto Aiello, Staccato Communications

  6. Summary • Band limited UWB system • Compliant with FCC 02-48, UWB Report & Order • 4.752GHz, 5.252GHz center frequency, 500MHz bandwidth at -10dB • Varies symbol rate, from 12.5kbps to 1.6Mbps at PHY-SAP • Due to time constraints this presentation addresses • Modulation scheme • Performance in AWGN channel • Remaining material will be presented at the next opportunity in March 2005 • Performance in multipath • Channelization • Implementation feasibility • Self evaluation criteria • Other issues that will emerge from group’s feedback Roberto Aiello, Staccato Communications

  7. FCC compliant • FCC compliant according to FCC UWB R&O • In this proposal the transmit signal occupies 500MHz at all times: frequency change is used to reduce ISI, not to spread the spectrum • “Thus, as long as the transmission system complies with the fractional bandwidth or minimum bandwidth requirements at all times during its transmission, we agree that it should be permitted to operate under the UWB regulations.” [FCC UWB R&O, B-32] Roberto Aiello, Staccato Communications

  8. System description • code length longer than 16 is required to define a reasonable number of codes with good cross-correlation properties • different piconets use different spreading codes • PRF (chip rate), 3.2 MHz is fairly high • Disadvantages • some impact of interchip interference with channel model 8 (industrial NLOS), • Advantages • it allows use of rate 1/2 coding at 100 kbps (we consider this one of the most important data rates) • It also allows implementation without frequency offset correction (with some performance loss) • it removes the need for frequency offset correction during acquisition, which leads to faster acquisition and a shorter preamble • After acquisition, frequency offset correction can be switched on to improve the performance • If the frequency offset estimate is good enough, it is possible to use partially coherent detection (with a coherent integration interval equal to the spreading code duration) instead of differential detection for further improved performance. • Pulse shape: 3rd-order Butterworth • FEC: 16-state convolutional code, with optional puncturing. Roberto Aiello, Staccato Communications

  9. Packet structure Roberto Aiello, Staccato Communications

  10. Spreading codes -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 Spreading codes of length 16 with minimal autocorrelation and cross-correlation, essential for acquisition, were found. Roberto Aiello, Staccato Communications

  11. 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

  12. Transceiver architecture (digital) A. differential detection for both acquisition and data demodulation B. differential detection for acquisition and non-coherent demodulation for data demodulation Roberto Aiello, Staccato Communications

  13. More on receiver • acquisition is based on differential detection, which allows shorter preamble • both differential and non-coherent detection are carried out separately for the different multipath components Architecture A. • differential detection for both acquisition and data demodulation. Architecture B. • differential detection for acquisition • non-coherent demodulation (with coherent combining across one codeword) for data demodulation • requires frequency offset estimation (during acquisition) and correction (during data demodulation) • differential detection without frequency offset correction. This is possible since the maximum frequency offset is roughly 220 kHz, which leads to a phase shift of 220000/3200000*360 = 25 degrees across one chip period. • differential detection with frequency correction (after acquisition). This will remove the 25 degrees phase shift, leading to some performance improvement. • non-coherent demodulation (with coherent combining across one codeword), which requires frequency offset correction. This should lead to a significant performance improvement, since we are now summing energy coherently across a whole codeword (which for data rates <= 100 kbps is 16 chips long). Roberto Aiello, Staccato Communications

  14. Differential combining Roberto Aiello, Staccato Communications

  15. Alternative analog transceiver architecture • Minimum receiver configuration • Potential sub-optimal performance • Potential low cost and power implementation Roberto Aiello, Staccato Communications

  16. Link budget Roberto Aiello, Staccato Communications

  17. System simulation parameters • Frequency band: 4.752GHz, 5.252 GHz (MB-OFDM band 4) • 10 dB bandwidth: 500 MHz • Transmit power: -16.1 dBm • Transmit filter: 3rd order Butterworth, corner frequency 180 kHz • Receive filter: 3rd order Butterworth, corner frequency 160 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

  18. PER vs. distance Roberto Aiello, Staccato Communications

  19. PER vs. Eb/No Roberto Aiello, Staccato Communications

  20. PER vs. received power Roberto Aiello, Staccato Communications

  21. Conclusions • UWB band limited system • Meet all system requirements • Low signal repetition frequency to reduce ISI 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

  22. 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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