June, 2005 IEEE P802.15-05/0341r0

IEEE P802.15

Wireless Personal Area Networks

Project / IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Title / Cairns/May05 failed confirmation vote - GIFFORD NO COMMENTS
Date Submitted / [10Jun05]
Source / [Ian C. Gifford]
[Freescale Semiconductor, Inc.]
[14 Windsor Road, Wellesley, MA USA 02481] / Voice: [+1 978 815 8182]
FAX: []
E-Mail: [
Re: / [-03/0047r7, 04/0493r1 and -05/0273r0, etc.]
Abstract / [Failed Confirmation vote, NO COMMENTS in support of my no vote.]
Purpose / [CONFIRMATION results: 44/36 or 55%/45%, Merged Proposal #1 MB-OFDM failed to confirm.]
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.

"No" vote comments on -04/0493r1 and -05/0273r0, Merged Proposal #1 aka MB-OFDM

  1. Regulatory status:
  2. The frequency hopping modes that are fundamental to MB-OFDM technology are based only on a waiver of the real FCC measurements rules for UWB. This special exception to the US rules will likely be revisited by the FCC in future proceedings, and is not an acceptable basis for the regulatory status of a major IEEE standard until formalized in FCC rules. Also, there seem to be no other regulatory administrations that are considering allowing the more interfering forms of frequency hopping UWB - even if they accept the baseline FCC rules from the UWB R&O.
  3. The plan of redundant mapping of data to "guard tones" is not acceptable: This "solution" to the problem of meeting the required minimum 500 MHz BW is unacceptable since it results in unnecessary emissions (sometimes in restricted bands) and will likely not result in any performance gains since the guard tones will be likely be destroyed by any reasonable filter implementation (only 20 MHz between passbands is very difficult to achieve without destroying guard tones). An alternative plan has been shown that increases the band separation & provides a better solution that does not require unnecessary emissions and gives better band separation.
  4. Claims about "spectral shaping" capabilities are unsubstantiated. Until details are provided, this claim must be understood to be just conjecture.
  5. No data have been presented on how "nulling" tones or OFDM symbols impacts link performance (especially at the critical rate of 480 Mbps for USB-type applications)
  6. Other literature suggests that active modulation of other tones on the edges of an intended "notch" is required to provide useable notches. No data has been presented to show the complexity of this active modulation mechanism.
  7. No data has been shown on how the nulling of tones to try to produce notches will impact spectral ripple and therefore transmit power (reducing performance).
  8. This is no data to show how the preamble would be altered to support a spectral notch (80% of preamble has flat spectrum and no "tones" to null)
  9. There is no proposed protocol for coordinating between different devices the nulling of tones or changes on hop sequence to "shape" the spectrum.
  10. The MB-OFDM proposal provides inferior range performance and has higher complexity than the DS-UWB proposal.
  11. No provision has been made in the MB-OFDM proposal to provide co-existence and interoperation with other forms of UWB like DS-UWB that will exist when MB-OFDM is deployed in the marketplace. The MB-OFDM proposal must add some provision (like CSM) that will support coordinated co-existence with DS-UWB.
  12. The MB-OFDM proposal does not scale to > 480 Mbps and so fails to meet requirements for higher data rates that are found in the TG3a CFA responses and Requirements Document. Please indicate that proposed method to achieve scalability to 1 Gbps PHY rate and also its complexity & performance in short range channels.
  13. The MB-OFDM proposal does not seem to scale well to lower complexity & lower power implementations that will be essential for handheld and mobile applications.
  14. The supporters of the MB-OFDM proposal seem to have adopted a different form of the technology for use in other places like WiMedia. These other forms do not seem to meet requirements of the PAR, selection criteria or requirements documents since they do not have a mandatory mode that can provide 110 Mbps at 10 m range. This completely undermines any claim that the MB-OFDM technology as proposed to the IEEE TG3a has also been chosen by other industry groups since the form used elsewhere does not meet TG3a requirements.
  15. All MB-OFDM performance analysis seems to be based on the assumption of 0 dB spectral ripple. This is not reasonable and does not seem to be possible based on public data showing measurements of real MB-OFDM and other OFDM systems.

If these comments are addressed satisfactorily, I will change my "no" vote to a "yes".

Submission Page XXX Ian C. Gifford, Freescale