1. 20th January 2011
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: Comprehensive rebuttal of proposed resolution of CID 29 in document
Date Submitted: 20th January 2010
Source: Joachim W. Walewski Company: Siemens AG
Address: Otto-Hahn-Ring 6, Munich, Germany
Voice: joachim.walewski (curly a) siemens.com
Re: Document
Abstract: In CID 29 an new band plan for is proposed. Document addresses this document and recommends to keep the current band plan. In this document I provide a point-by-point rebuttal of the arguments made in and demonstrate, that the rational behind the current band plan is flawed (LED spectra) and that other arguments are debatable at least. Due to the lack of technical/empirical support for the current band plan and the benefits of the proposed band plane I recommend accepting the latter.
Purpose: Resolution of CID 29 in
Notice: This document has been prepared to assist the IEEE P 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 P
Joachim W. Walewski, Siemens AG

2. Communication Technologies
20th January 2011
Comprehensive rebuttal of proposed resolution of CID 29 in document
Joachim W. Walewski
Corporate Technology
Communication Technologies
Siemens AG
Joachim W. Walewski, Siemens AG

3. Background and approach
20th January 2011
Background and approach
Document recommends to keep current band plan in
If arguments supporting the current band plan are solid and make band plan proposed in CID 29 less attractive, CID 29 should indeed be rejected
I conducted a step-by-step analysis of the arguments provided in
Organisation of this contribution:
Review of my step-by-step analysis
Summary and assessment of arguments for and against both band plans
My recommendation concerning CID 29
Joachim W. Walewski, Siemens AG

4. First argument (slide 3)
20th January 2011
First argument (slide 3)
Rebuttal:
Yes, standards do not explicitly address receivers, but that does not mean that the standard should be drafted in ignorance of typical receiver characteristics ( implicit consideration).
Implicit consideration in, e.g. eye diagram (information for both Tx and Rx).
Let us assume that changing some technical parameters (adapting the prototypical Tx to typical receivers) improves the performance of standard-compliant products without compromising the fidelity of the transceiver or the link.
If the proposed change does not come at a prohibitive technical „cost“, I do not see a valid reason for not implementing this change.
So: let‘s analyse whether either band plan is better suited for typical transmitters (and receivers).
Joachim W. Walewski, Siemens AG

5. Second argument (slide 3)
20th January 2011
Second argument (slide 3)
Rebuttal:
Implicit justification for the spectral chart used on slide 4 in
As shown in , there are other applications (e.g., medical diagnostics) in which the human eye is not considered. Another growing market: fibre-based communications.
Concerning „single-colour“ LEDs, manufacturers strive to lower the optical bandwidth (better colour-mixing fidelity and better match for other applications). I.e., the spectral chart shown in is not a good candidate for illumination/signalling.
Argument does thus not hold and implicit justification of the used spectral charts is not supported.
Joachim W. Walewski, Siemens AG

6. Third argument (slide 4)
20th January 2011
Third argument (slide 4)
These are anything but typical LED spectra (see )
An argument based on the spectral characteristics of this unrepresentative choice is going to be flawed
Joachim W. Walewski, Siemens AG

7. Fourth argument (slide 5)
20th January 2011
Fourth argument (slide 5)
Rebuttal:
This would be true if the current band plan indeed supports typical LED spectra best
Based on third argument (spectral chart), which is flawed
Joachim W. Walewski, Siemens AG

8. Fifth arguments (slide 5)
20th January 2011
Fifth arguments (slide 5)
Rebuttal:
The same is true if CID 29 is accepted.
Joachim W. Walewski, Siemens AG

9. 20th January 2011
Main recommendation
Is based on flawed choice of LED spectra (see argument three). Provides hence no justification for existing ban plan.
Promoter(s) of not implementing the new band plan have still not provided evidence that the current band plan accommodates the plethora of LED spectra better than the proposed band plan!
Joachim W. Walewski, Siemens AG

10. 20th January 2011
Summary
Argument 1 (against Rx-based band plan): flawed due to not considering implicit consideration of Rx characteristics.
Argument 2 (manufacturer’s choice of LED spectra based on eye characteristics): not generally true and does thus not justify chosen LED spectra
Argument 3 (chosen LED spectra): fundamentally flawed since they do not represent typical LED spectra (even for lighting purposes)
Joachim W. Walewski, Siemens AG

11. 20th January 2011
Summary (cont‘d)
Fourth argument (external reasons for LED choice): Centrally based on argument three, which is flawed.
Fifth argument (band agglomeration): does not favour either existing or new band plan.
Main recommendation: based on flawed spectral chart; also, no proof provided that this indeed is the best dissection
Joachim W. Walewski, Siemens AG

12. Argumentative structure
20th January 2011
Argumentative structure
Argument against Rx-centred band plan (# 1): flawed
Argument for chosen spectra (# 2 & 3 & 4): contradicted by reality
Argument based on band agglomerations (# 5): does not favour either band plan
Main recommendation: based on unjustified, narrow selection of LEDs.
Joachim W. Walewski, Siemens AG

13. Conclusion Argument against CID 29‘s approach (Rx based) flawed
20th January 2011
Conclusion
Argument against CID 29‘s approach (Rx based) flawed
Arguments for existing band plan wanting
No proof provided, that proposed band plan matches spectra of commercially available LEDs worse.
Band-plan agglomeration supports either band plan.
New band plan based on thorough analysis, promising benefits, and without thus far discernible negative implications for transmitter performance
I therefore oppose the recommendation in and support the adoption of the band plan outlined in CID 29
Joachim W. Walewski, Siemens AG