Just a small correction:
I did send the link to 802.11af chairs for distributions to that task group and
invited comments from them.
Also, the PAWS progress is presented at every 802.11 plenary meeting, so
interested folks should know about the document and its status.
- Gabor
-----Original Message-----
From: ext Rosen, Brian [mailto:[email protected]]
Sent: Wednesday, December 11, 2013 6:14 AM
To: Eliot Lear
Cc: Bajko Gabor (Nokia-CTO/SiliconValley); <[email protected]>
Subject: Re: [paws] wglc on
https://datatracker.ietf.org/doc/draft-ietf-paws-protocol/
I'll take a stab at answering this:
On Dec 11, 2013, at 8:12 AM, Eliot Lear <[email protected]> wrote:
Hi Gabor,
I don't think you can call this a full review, but I do have a few
questions/issues.
Two general questions:
Could my cell phone or Wifi-enabled device be a Slave or Master Device
in order to make use of the database or is the intent that only base
stations be the target?
In most regulatory environments, the device that has the radio in the shared
spectrum must contact the database. You could imagine having a whitespace
radio in a next get cell phone, but generally the answer to the question is no.
Having said that, a database could, if it wanted to, grant anyone access to
the database.
Also, have we liaised this document to the IEEE 802.11 people and
do/would they care (see below about licensed/unlicensed)?
We have connected with the 802.22 folks, not 802.11.
4.1. Database Discovery (and elsewhere):
4.1. Database Discovery
Different regulators may have different requirements for the approval
and operation of databases, such as:
o A regulator may only allow a limited number of certified databases
to operate. It also may require the certification of each device-
to-database pairing.
o A regulator may maintain a trusted website that lists all approved
databases, known as the Listing Server. It also may mandate how
devices use the listing server.
o A regulator may allow each database to define its own terms of
use, so that, for example, an approved device may not be able to
access all approved databases.
The basis of this document is that the regulators are in direct
contact with the Master Device.
No. The database is in contact with the device, not the regulators. The
regulators authorize the database, have access to it, but do not operate or
manipulate it directly.
I have some concerns about that approach:
1. It would seem to me computationally intensive on the part of the
regulator to compute a geometry/contour to determine which frequencies
are available. As much as I would be worried about a single request, I
don't see why regulators would want to take such aggregate load. Has a
regulator agreed to do so? Or am I wrong about the computation?
The database does the computation. The contour calculations can be done in
advance, but would have to change as protected primary users change their use.
The database operation locates the device within the set of precalculated
protected contours to determine which ones reduce the spectrum available to the
whitespace device.
2. Much of this seems to be predicated on micro-auctions in secondary
spectrum. Interesting idea and worth pursuing, however, the one week
period below seems to lead us to question what "micro" means in this
context. See below for that
You are incorrect. All secondary users (whitespace devices) in the same
location get the same spectrum availability. There is no mechanism to allocate
or share that available spectrum. There is some desire to provide that kind of
service, but it is beyond our charter.
.
3. I may be demonstrating my parochial nature, but there is a lot of
complexity in this document that is predicated on the assumption that
licensed use will be permitted. That is- a specific station license is
required to transmit. Wouldn't this protocol simplify considerably if
it focused on unlicensed use? In fact, wouldn't it boil down to a file
transfer protocol and a database format as opposed to bouncing all of
these queries back and forth? My question really is how the authors
came to this approach. I can imagine some arguments, such as wanting to
track down bad actors, but I raise the issue because of the plethora of
PII that could end up getting shipped to regulators on a regular basis
over this.
You have an incorrect model.
There is a set of licensed, protected users. The database knows about them,
and calculates contours to assure their use is protected. There is a set of
unlicensed, but type-approved whitespace devices (which includes masters and
slaves). They are secondary users - they can use spectrum if none of the
primary, licensed users use it. The secondary, unlicensed users ask the
database what spectrum is available at their location at that time. The
database calculates which primary users would be affected by a secondary
transmitter at that location and remove the primary user's spectrum from the
available secondary spectrum. The database returns what is left (what spectrum
is not used by any primary user at that location at that time).
All of this is provided in a regulated environment. The regulator decides what
the protections are, and what the unlicensed devices have to do to use the
available spectrum.
Section 4.1.1:
Within a regulatory domain that has a Database Listing Server, a
Device MUST use it to determine the URLs of databases for the domain.
The URI of the Listing Server for a regulatory domain MAY be
preconfigured in the device. Where allowed by the regulator, the
Device MAY save the database list and SHOULD contact the Database
Listing Server periodically to update its list. The time between
such updates MUST be no longer than one week, or any update interval
required by the applicable regulatory domain, whichever is shorter.
I presume that in this paragraph, when you say "Device" you mean "Master
Device". going further, it seems to me that the point should not be
whether or not such a device has direct Internet connectivity, but
whether or not it can receive updates. Those updates could conceivably
come from many sources, including ones in which IP is not used.
This section is referring to the process by which the device (a master device
if there are master/slave devices) locates the database. Not every use has
slaves. In some countries, there is a listing service of multiple competing
database operators. Only a database on that list may be used. This is the
control the regulator has on de-authorizing databases.
The PAWS protocol is based on IP transports. We don't consider models where
there are alternatives to IP to access the listing service or the database.
Moreover, there seems to have been an arbitrary period of time chosen (1
week). Why not state that in terms of the EventTime in AVAIL_SPECTRUM_RESP?
Again, this is the frequency at which the listing service must be requeried,
not the database. The frequency is normally set by the regulatory domain, and
devices have to be built for one or more regulatory domains. It's much less
often than the spectrum query. This basically determines how quickly a
regulator can de-authorize a database.
Thanks,
Eliot
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