Hello All,
As editors of the problem statement, use cases & requirements draft we are
attempting to prepare a completed draft which could be ready for working
group last call before IETF83. In the coming days we will post the
sections of the draft to the mailing list. Our request is that you review
these sections and reply to the email with any comments.
Below is the text for section 5. This text has not changed from version-01
as uploaded October 31, 2011. Our goal is that any discussion on this text
will conclude by February 1. To be clear, approval of the document will go
through the normal process of last calls etc.. We are simply asking for
your assistance in preparing a complete & accurate document that could
progress the work. So please review the text and send your comments either
directly to the editor or to the mailing list.
Kind Regards,
Raj & Scott
5. Problem Statement
The use of white space spectrum is enabled via the capability of a
device to query a database and obtain information about the
availability of spectrum for use at a given location. The databases
are reachable via the Internet and the devices querying these
databases are expected to have some form of Internet connectivity,
directly or indirectly. The databases may be country specific since
the available spectrum and regulations may vary, but the fundamental
operation of the protocol should be country independent.
An example high-level architecture of the devices and white space
databases is shown in the figure below:
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-----------
|WS Device| ------------
|Lat: X |\ .---. /--------|Database X|
|Long: Y | \ ( ) / ------------
----------- \-------/ \/ o
( Internet ) o
----------- /------( )\ o
|WS Device| / (_____) \ ------------
|Lat: X |/ \--------|Database Y|
|Long: Y | ------------
-----------
Figure 11: High level view of the White space database architecture
In the figure above, note that there could be multiple databases
serving white space devices. The databases are country specific
since the regulations and available spectrum may vary. In some
countries, for example, the U.S., the regulator has determined that
multiple, competing databases may provide service to White Space
Devices.
A messaging interface between the white space devices and the
database is required for operating a network using the white space
spectrum. The following sections discuss various aspects of such an
interface and the need for a standard. Other aspects of a solution
including provisioning the database, and calculating protected
contours are considered out of scope of the initial effort, as there
are significant differences between countries and spectrum bands.
5.1. Global applicability
The use of TV white space spectrum is currently approved by the FCC
in the United States. However regulatory bodies in other countries
are also considering similar use of available spectrum. The
principles of cognitive radio usage for such spectrum is generally
the same. Some of the regulatory details may vary on a country
specific basis. However the need for devices that intend to use the
spectrum to communicate with a database remains a common feature.
The database provides a known, specifiable Protection Contour for the
primary user, not dependent on the characteristics of the White Space
Device or it's ability to sense the primary use. It also provides a
way to specify a schedule of use, because some primary users (for
example, wireless microphones) only operate in limited time slots.
Devices need to be able to query a database, directly or indirectly
over the public Internet and/or private IP networks prior to
operating in available spectrum. Information about available
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spectrum, schedule, power, etc. are provided by the database as a
response to the query from a device. The messaging interface needs
to be:
1. Radio/air interface agnostic - The radio/air interface technology
used by the white space device in available spectrum can be
802.11af, 802.16, 802.22, LTE etc. However the messaging
interface between the white space device and the database should
be agnostic to the air interface while being cognizant of the
characteristics of various air-interface technologies and the
need to include relevant attributes in the query to the database.
2. Spectrum agnostic - the spectrum used by primary and secondary
users varies by country. Some spectrum has an explicit notion of
a "channel" a defined swath of spectrum within a band that has
some assigned identifier. Other spectrum bands may be subject to
white space sharing, but only have actual frequency low/high
parameters to define protected entity use. The protocol should
be able to be used in any spectrum band where white space sharing
is permitted.
3. Globally applicable - A common messaging interface between white
space devices and databases will enable the use of such spectrum
for various purposes on a global basis. Devices can operate in
any country where such spectrum is available and a common
interface ensures uniformity in implementations and deployment.
Since the White Space device must know it's geospatial location
to do a query, it is possible to determine which database, and
which rules, are applicable, even though they are country
specific.
4. Address regulatory requirements - Each country will likely have
regulations that are unique to that country. The messaging
interface needs to be flexible to accommodate the specific needs
of a regulatory body in the country where the white space device
is operating and connecting to the relevant database.
5.2. Database discovery
Another aspect of the problem space is the need to discover the
database. A white space device needs to find the relevant database
to query based on its current location or for another location.
Since the spectrum and databases are country specific, the device
will need to discover the relevant database. The device needs to
obtain the IP address of the specific database to which it can send
queries in addition to registering itself for operation and using the
available spectrum.
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5.3. Protocol
A protocol that enables a white space device to query a database to
obtain information about available channels is needed. A device may
be required to register with the database with some credentials prior
to being allowed to query. The requirements for such a protocol are
specified in this document.
5.4. Data model definition
The contents of the queries and response need to be specified. A
data model is required which enables the white space device to query
the database while including all the relevant information such as
geolocation, radio technology, power characteristics, etc. which may
be country and spectrum and regulatory dependent. All databases are
able to interpret the data model and respond to the queries using the
same data model that is understood by all devices.
Use of XML for specifying a data model is an attractive option. The
intent is to evaluate the best option that meets the need for use
between white space devices and databases.
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