Compromise for UWB Interoperability

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Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
Compromise for UWB Interoperability PHY
Overview Date Submitted 20 February,
2004 Source John McCorkle Company Motorola,
Inc Address 8133 Leesburg Pike Voice703-269-3
000, FAX [phone], E-Mailjohn_at_xtremespec
trum.com Re IEEE 802.15.3a Call For Intent to
Present for Ad-Hoc Meeting Abstract This
document provides an overview of a proposed
Common Signaling Mode that would allow the
inter-operation or MB-OFDM and DS-UWB
devices. Purpose Promote further discussion
and compromise activities to advance the
development of the TG3a Higher rate PHY
standard. 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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Talking with each other Basic Requirements

• Each class of UWB devices (MB-OFDM or DS-UWB)
  needs a way to send messages to the other type
• MB-OFDM ? DS-UWB
• DS-UWB ? MB-OFDM
• Even better, design a common signaling mode that
  can be understood by either class of devices
• Goal Minimize additional complexity for each
  type of device while enabling this extra form of
  communications
• Use existing RF components DSP blocks to
  transmit message to other-class devices
• Also need to support a low-complexity receiver
• Lower rate mode could be acceptable if it can be
  used to provide robust control functions

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Interoperability Signal Generation

• One waveform that would be straightforward for
  either class of device ia a BPSK signal centered
  in the middle of the low band at 4GHz
• Such a signal could be generated by both MB-OFDM
  and DS-UWB devices using existing RF and digital
  blocks
• MB-OFDM device contains a DAC nominally operating
  at 528 MHz
• A 528 MHz BSPK (3 dB BW) signal is likely too
  wide for MB-OFDM band filters
• DAC an be driven at slightly lower clock rate to
  produce a BPSK signal that will fit the MB-OFDM
  Tx filter
• Result is a 500 MHz wide BPSK signal that a
  DS-UWB device could receive demodulate
• DS-UWB device contains a pulse generator
• Use this to generate a 500 MHz BPSK signal at
  lower chip rate
• This signal would fit MB-OFDM baseband Rx filter
  and could be demodulated by the MB-OFDM receiver

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MB-OFDM DS-UWB Signal Spectrum with CSM
Compromise Solution
MB-OFDM (3-band) Theoretical Spectrum
Relative PSD (dB)
Proposed Common Signaling Mode Band (500 MHz
bandwidth)
DS-UWB Low Band Pulse Shape (RRC)
0
-3
-20
3960
3432
4488
Frequency (MHz)
3100
5100
FCC Mask
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Conclusions

• The creation of a common signaling mode will
  allow co-existence and interoperability between
  DS-UWB and MB-OFDM devices
• A Common Signaling Mode is described that
• Requires minimal additional cost/complexity in
  MB-OFDM DS-UWB
• Achieves desired data rates and robust
  performance
• Prevents coexistence problems for two different
  UWB PHYs
• Provides interoperability in a shared piconet
  environment