Re: [ipwave] Commenting on the FCC plan

Alexandre Petrescu <> Fri, 24 January 2020 14:11 UTC

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From: Alexandre Petrescu <>
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Date: Fri, 24 Jan 2020 15:11:26 +0100
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Subject: Re: [ipwave] Commenting on the FCC plan
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for information, the filing is now visible at

Le 15/01/2020 à 21:34, Alexandre Petrescu a écrit :
> I submitted the comments that are shown in the attached file.
> It is possible to submit more comments, maybe with more help from 
> interested parties, or to clarify other things.  It's the same URL 
> Alex
> Le 15/01/2020 à 21:11, Alexandre Petrescu a écrit :
>> 6. "In support of its waiver request, 5GAA submitted studies of using 
>> 10- and 20-megahertz-wide channels for C-V2X that found that allowing 
>> operation on a single 20-megahertz channel will support the introduction
>> of services “that [will] enable many important safety applications, 
>> such as red light warnings, basic safety messages, emergency alerts, 
>> and others, to enhance traffic systems and operations.”"
>> My comment is the following: one would benefit from considering 
>> carefully the statements from 5GAA.  Depending how it is interpreted 
>> it might be advantageous or not.  For my part, I do think that some of 
>> the claims of 5GAA in some trials make confusions about cellular 
>> technology and DSRC technology.  I do think that there is at least one 
>> publicly demonstrated trial under the banner of 5GAA which uses DSRC 
>> but it claims cellular technology.
>> That said, with respect to the use of the term "C-V2X": it is not very 
>> clear throughout the FCC Notice whether C-V2X means the traditional 
>> traits of cellular technology that distinguishes it from WiFi (i.e. 
>> use cellular frequencies, use a SIM, specific codecs, mandatory base 
>> station, etc.) or otherwise it means some more generic "3GPP" 
>> technology.  The only place where C-V2X is defined more properly is 
>> when, on page 37, it refers to 3GPP Release 14.  There is no pointer 
>> to a particular 3GPP Rel 14 document.  This lets open the imagination 
>> to think that it might mean the WiFi aspects of 3GPP.  3GPP is known 
>> to spec things by stepping into WiFi domain very often, even though in 
>> practice there are no 3GPP deployments on WiFi - and that, since 3G 
>> onwards :-)  In this sense, it might be that 'C-V2X' already means 
>> something from WiFi, and why not C-V2X to mean 802.11-OCB and BSM 
>> messages?
>> This lack of precision in mentioning "C-V2X" is what adds a lot to the 
>> confusion - should one accept C-V2X in 5.9GHz bands?  Well yes, 
>> provided 'C-V2X' means a WiFi issued by 3GPP by copy/pasting IEEE.  
>> Well no, if 'C-V2X' means a pure cellular interface with a SIM card or 
>> software, mandatory base station, cellular codecs and specific 
>> expensive specific IPR from well-known particular companies.
>> 7. "With this Notice, we propose that ITS in this band continue to 
>> provide safety of life services. We seek comment on this proposal."
>> This is my comment, and backed by a colleague from IETF: on which 
>> channel should we run IPv6-over-OCB? (RFC 8691)
>> 8. "C-V2X in the 5.905-5.925 GHz band. Specifically, we propose to 
>> authorize C-V2X operations in the upper 20 megahertz of the band 
>> (5.905-5.925 GHz). We seek specific and detailed comment on this 
>> proposal that can fully inform our decision."
>> This is my detailed comment: when one wants to authorize a particular 
>> technology on a particular band, then one would like to make sure that 
>> technology is fully specified and understood.  It is not the case now 
>> with 'C-V2X'.  It is a rather new term.  Is it only the V2X part of 
>> 3GPP?  Is it the WiFi part of it?  Which spec is meant more precisely?
>> This is why, in return, I would like to comment and request to 
>> publicize what more precisely is it meant by C-V2X?
>> 8. "We seek comment on the available technical studies on C-V2X that 
>> should inform our consideration of C-V2X, including any recent studies
>> that provide information about how C-V2X would operate in the 5.9 GHz 
>> band."
>> Where are these technical studies?  Which ones?
>> 9. "We first seek comment on whether to authorize C-V2X operations in 
>> the 5.895-5.905 GHz band."
>> My answer is no.  C-V2X is not specified, and it is a too wide term 
>> that might mean too many things.  If C-V2X means the WiFi part of 
>> 3GPP, and in particular 802.11-2016, in particular OCB mode, in 
>> particular BSM messages, then the answer is yes, definitely.  This 
>> would also allow RFC 8691 IPv6 over 802.11-OCB to work.
>> 10. "Commenters should provide detailed justification to support 
>> specific band plan options, including the types of services that could 
>> or could not be delivered by unlicensed use or by vehicularrelated
>> services under each option."
>> The type of the service that I need is the following: forming of 
>> convoy of 3 self-driving cars - they use IPv6 over 802.11-OCB on 3 
>> distinct 5.9GHz channels in order to minimize interference.   This 
>> could not be delivered if only one channel was available for RFC 8691 
>> IPv6-over-802.11-OCB.  The demo is filmed and publicly available on 
>> the web.
>> 11. "(a) DSRCS Roadside Units (RSUs) operating in the 5895-5905 MHz 
>> band must comply with the technical standard Institute of Electrical 
>> and Electronics Engineers (IEEE) 802.11p-2010."
>> This forgets that 802.11p is an old name and no longer in use.  The 
>> users of this name neglect that IEEE 802.11-2016 is the current spec, 
>> and which covers old 802.11p behaviour with an 'OCB' mode (Outside the 
>> Context of a BSSID).  That is the standard that should be referred to 
>> by this FCC Notice and not 802.11p.
>> Additionally, I suggest to add the keyword 'IPv6'.  I suggest to add a 
>> reference to RFC 8691 titled "Basic Support for IPv6 Networks 
>> Operating Outside the Context of a Basic Service Set over IEEE Std 
>> 802.11" which is publicly available on the web.
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