PSWF Pulse and Ternary Complementary Coding for DS-UWB

1
Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
PSWF-based SSA Pulse Wavelets and Ternary
Complementary Sets for DS-UWB Date Submitted
13 September, 2004 Source (1) Honggang
Zhang, (1) Imrich Chlamtac, (2) Chihong Cho, and
(2) Masao Nakagawa Company (1) Create-Net,
(2) Keio University Connectors Address Via
Solteri, 38, 38100 Trento, ITALY Voice39-0461-
828584 , FAX [phone] , E-Mail
honggang.zhang_at_create-net.it, imrich.chlamtac_at_cre
ate-net.it, cho_at_nkgw.ics.keio.ac.jp,
nakagawa_at_nkgw.ics.keio.ac.jp Re IEEE P802.15
Alternative PHY Call For Proposals, IEEE
P802.15-02/327r7 Abstract In order to realize
scalable data rate transmission for IEEE
802.15.3a UWB WPAN, PSWF-based SSA pulse wavelets
and ternary complementary sets are investigated
for DS-UWB. Purpose For investigating the
characteristics of High Rate Alternative PHY
standard in 802.15TG3a based on the PSWF-type SSA
pulse wavelets and ternary complementary sets.
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.
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PSWF-based SSA Pulse Wavelets and Ternary
Complementary Sets for DS-UWB
Honggang ZHANG, Imrich CHLAMTAC Create-Net,
Italy Chihong CHO, Masao NAKAGAWA Keio
University, Japan
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Outline of presentation

• Overview of previous improvements in DS-UWB
• PSWF-type SSA pulse wavelets for DS-UWB
• Ternary complementary sets for DS-UWB
• Improving DS-UWB by combining PSWF-type SSA pulse
  wavelets with ternary complementary sets
• 5. Conclusion remarks
• 6. Backup materials

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CREATE-NET
5
Create-Net in Trento, Italy
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1. Overview of previous improvements in DS-UWB

• Support for much higher data rates
• BPSK modulation using variable length spreading
  codes
• At same time, much lower complexity and power
• Essential for mobile handheld applications
• Digital complexity is 1/3 of previous estimates,
  yet provides good performance at long range and
  high rates at short range
• Harmonization interoperability with MB-OFDM
  through the Common Signaling Mode (CSM)
• A single multi-mode PHY with both DS-UWB and
  MB-OFDM
• Best advantages of both approaches with most
  flexibility

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DS-UWB operating bands SOP
Low Band
High Band
3
4
5
6
7
8
9
10
11
3
4
5
6
7
8
9
10
11
GHz
GHz

• 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

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2. PSWF-type SSA pulse wavelets for DS-UWB
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Designing PSWF-based SSA pulse wavelets
Prolate Spheroidal Wave Functions (PSWF)

• Not just trying to construct a pulse waveform in
  order to satisfy the FCC spectral mask, on the
  contrary, first starting from considering a
  required spectral mask in frequency domain
  (band-limited), and then finding its
  corresponding pulse waveform in time domain
  (time-limited).
• Just as C. E. Shannon has asked a question once
  upon a time, To what extent are the functions
  which confined to a finite bandwidth also
  concentrated in the time domain? , which has
  given rise to the discovery and usage of Prolate
  Spheroidal Wave Functions (PSWF) in the sixties.
• Designing a time-limited band-limited pulse
  waveform is extremely important in UWB system.

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Features of PSWF-based pulse wavelets

• Pulse waveforms are doubly orthogonal to each
  other.
• Pulse-width and bandwidth can be simultaneously
  controlled to match with arbitrary spectral mask
  adaptively.
• Pulse-width can be kept same for all orders of m.
• Pulse bandwidth is same for all orders of m.
• They can be utilized for simple transceiver
  implementation since frequency shift, e.g.,
  up-conversion or down-conversion with mixer as in
  former MB-OFDM and DS-UWB of IEEE 802.15.3a is no
  longer necessary.

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Orthogonal PSWF-based SSA pulse wavelets (3.1-5.6
GHz, order of 1, 2, 3 and 4)
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Improving Common Signaling Mode (CSM) based on
PSWF-type SSA pulse wavelets
1
3
12
23
13
Orthogonal PSWF pulse wavelet generation
(3.120-4.264 GHz, order of 1, 2, 3 and 4)
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Orthogonal PSWF pulse wavelet generation
(3.692-4.836 GHz, order of 1, 2, 3 and 4)
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Dual-band PSWF pulse wavelet generation
(3.120-3.692 GHz, 4.264-4.836 GHz)
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3. Ternary complementary sets for DS-UWB
PSWF-type SSA pulses
Ternary complementary set
Reference Di Wu, P. Spasojevic, and Ivan Seskar,
Ternary complementary sets for orthogonal pulse
based UWB, 37th Asilomar Conference on Signals,
Systems and Computers, Nov. 9-12, 2003.
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Design ternary complementary sets
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Design ternary MO (mutually orthogonal)
complementary sets
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Design ternary MO complementary sets (cont.)
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Design ternary MO complementary sets (cont.)
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BER vs. Eb/No (CM1, multi-users 4)
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BER vs. Eb/No (CM1, multi-users 8)
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4. Improve DS-UWB utilizing PSWF-type SSA pulse
wavelets and ternary complementary sets
DS-UWB scaling to higher rates

• There is significant interest in cable
  replacement applications that require high speed
  operation (480 Mbps) at short range
• Current DS-UWB operation at 500 Mbps uses L2
  code ¾ FEC
• Complexity is similar DS-UWB receiver for 110
  220 Mbps
• Same ADC bit widths clock rates
• Same rake bit width complexity
• Fewer Rake taps available (only 2/3 as many as
  for 220 Mbps)
• Viterbi decoder for k6, rate ¾ likely 2x gates ?
  45k gate increase
• Current operation at 660 Mbps also supported with
  un-coded operation
• 4.9 m range in fully impaired AWGN simulation
• Eliminates requirement for high speed Viterbi
  decoder

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DS-UWB signal generation
Scrambler
K6 FEC Encoder
Conv. Bit Interleaver
Input Data
Bit-to-Code Mapping
Pulse Shaping
Center Frequency
Gray or Natural mapping
K4 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 k6 convolutional code
• K4 encoder can be used for lower complexity at
  high rates or to support iterative decoding for
  enhanced performance.
• 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

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Data rates supported by DS-UWB (low-band)
Data Rate FEC Rate Code Length Range (AWGN)
28 Mbps ½ 24 35 m
55 Mbps ½ 12 27 m
110 Mbps ½ 6 22.2 m
220 Mbps ½ 3 16.2 m
500 Mbps ¾ 2 7.5 m
660 Mbps 1 2 4.7 m
1000 Mbps ¾ 1 4.8 m
1320 Mbps 1 1 3.3 m
Similar modes have defined for high band
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High data rate applications

• Critical for cable replacement applications such
  as wireless USB (480 Mbps) and Wireless 1394 (400
  Mbps)
• High rate device supporting 480 Mbps
• DS-UWB device uses shorter codes (L2, symbol
  rate 660 MHz)
• Uses same ADC rate bit width (3 bits) and rake
  tap bit widths
• Rake combining use fewer taps at a higher rate
  or same taps with extra gates
• Viterbi decoder complexity is 2x the baseline
  k6 decoder
• Can operate at 660 Mbps without Viterbi decoder
  for super low power

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5. Conclusion remarks

• PSWF-type pulse wavelets have been proposed for
  improving DS-UWB performance.
• We also have analyzed the ternary MO
  complementary code sets for DS-UWB with higher
  data rate.
• Scalable and adaptive performance improvement can
  be expected by utilizing the PSWF-based SSA-UWB
  and ternary MO complementary sets.

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6. Background materials
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Design PSWF-based SSA pulse wavelets
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Realization of SSA-UWB pulse wavelet design
Prolate Spheroidal Wave Functions (PSWF)

• Not just trying to construct a pulse waveform in
  order to satisfy the FCC spectral mask, on the
  contrary, first starting from considering a
  required spectral mask in frequency domain
  (band-limited), and then finding its
  corresponding pulse waveform in time domain
  (time-limited).
• Just as C. E. Shannon has asked a question once
  upon a time, To what extent are the functions
  which confined to a finite bandwidth also
  concentrated in the time domain?, which has
  given rise to the discovery and usage of Prolate
  Spheroidal Wave Functions (PSWF) in the sixties.
• Designing a time-limited band-limited pulse
  waveform is extremely important in UWB system.

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Designing method of optimized SSA-UWB wavelets
using PSWF
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Designing method of optimized SSA-UWB wavelets
using PSWF (cont.)
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Whats Prolate Spheroidal Wave Functions (PSWF)?
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Characteristics of PSWF-based pulse wavelets

• Pulse waveforms are doubly orthogonal to each
  other.
• Pulse-width and bandwidth can be simultaneously
  controlled to match with arbitrary spectral mask
  adaptively.
• Pulse-width can be kept same for all orders of m.
• Pulse bandwidth is same for all orders of m.
• They can be utilized for simple transceiver
  implementation since frequency shift, e.g.,
  up-conversion or down-conversion with mixer as in
  MB-OFDM and DS-UWB of IEEE 802.15.3a is no longer
  necessary.

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Numerical solution of PSWF
36
Numerical solution of PSWF (cont.)
Discrete-time solution of Prolate Spheroidal
Wave Functions (PSWF) with eigenvalue
decomposition
37
Orthogonal pulse waveform generation based on
PSWF (3.1-10.6 GHz, order of 1, 2 and 3).
38
Orthogonal pulse waveform generation based on
PSWF (3.1-5.6 GHz, order of 1, 2, 3 and 4).