Individual Submission B. Patil, Ed.
Internet-Draft
Intended status: Informational S. Probasco
Expires: August 26, 2011 G. Bajko
Nokia
February 22, 2011
Protocol to Access White Space database: Problem statement and
Requirements
draft-patil-paws-problem-stmt-00
Abstract
Governments around the world continue to search for new pieces of
radio spectrum which can be used by the expanding wireless
communications industry to provide Broadband Wireless Access (BWA).
The concept of allowing secondary or unlicensed transmissions in
frequencies occupied by a primary or licensed user is a technique to
"unlock" existing spectrum for new use. An obvious requirement is
that these secondary or unlicensed transmissions do not interfere
with the primary or licensed use of the spectrum. The fundamental
issue is how to determine for a specific location and specific time
if any TV channels are available for unlicensed use, e.g. they are
not being used for TV broadcast or by a wireless microphone.
Academia and Industry have studied multiple cognitive radio enablers
for use in such a scenario. The methods of geolocation and database
have been shown to achieve favorable results. This document
discusses the requirements and the problems that need to be addressed
for enabling the use of white-space spectrum by obtaining information
from a database.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 26, 2011.
Patil, et al. Expires August 26, 2011 [Page 1]
Internet-Draft PAWS: PS and Reqmts February 2011
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Concepts . . . . . . . . . . . . . . . . . . . 4
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. The concept of Cognitive Radio . . . . . . . . . . . . . . 5
3. Background information on white space in US . . . . . . . . . 5
4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Global applicability . . . . . . . . . . . . . . . . . . . 7
4.2. Database discovery . . . . . . . . . . . . . . . . . . . . 7
4.3. Data model definition . . . . . . . . . . . . . . . . . . 8
4.4. Security requirements . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
9. Informative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
Patil, et al. Expires August 26, 2011 [Page 2]
Internet-Draft PAWS: PS and Reqmts February 2011
1. Introduction
Governments around the world continue to search for new pieces of
radio spectrum which can be used by the expanding wireless
communications industry to provide Broadband Wireless Access (BWA).
One area which has received much attention globally is the TV white
space: portions of the TV band that are not used by broadcasters. In
2008 the FCC took beginning steps when they published their first
ruling on use of TV white space, and then followed up with a final
ruling in 2010[FCC ruling]. Finland passed an Act in 2009 enabling
testing of cognitive radio systems in the TV white space. The ECC
has completed Report 159 [ECC Report 159] containing requirements for
operation of cognitive radio systems in the TV white space. Ofcom
published in 2004 their Spectrum Framework Review [Spectrum Framework
Review] and their Digital Dividend Review [DDR] in 2005, and have
followed up with a proposal to access TV white space.
The concept of allowing secondary or unlicensed transmissions in
frequencies occupied by a primary or licensed user is a technique to
"unlock" existing spectrum for new use. An obvious requirement is
that these secondary or unlicensed transmissions do not interfere
with the primary or licensed use of the spectrum. The fundamental
issue is how to determine for a specific location and specific time
if any TV channels are available for unlicensed use, e.g. they are
not being used for TV broadcast or by a wireless microphone.
Academia and Industry have studied multiple cognitive radio enablers
for use in such a scenario. The methods of geolocation and database
have been shown to achieve favorable results, and are thus the basis
for rulings by the FCC and reports from ECC and Ofcom. However, the
two cognitive radio enablers of geolocation and database are a
framework, not a complete solution. There is a choice of which
parameters and which algorithms to use in determining spectrum
availability. The ongoing challenge is to maximize the spectrum
available for unlicensed use while at the same time ensuring no
interference to the licensed use of the spectrum.
In a typical implementation of geolocation and database to access TV
white space, a radio is configured with its location in latitude and
longitude. There are multiple ways to configure this location
information, e.g. programmed at installation (e.g. for a fixed
device) or determined by GPS (e.g. for a or mobile device). At
power-on, before the device can transmit in TV white space
frequencies, the device must contact a database, provide its
geolocation and receive in return a list of unoccupied or "white
space" channels. The device can then select one of the channels from
the list (note that it is possible they list is empty; there are no
unoccupied channels at the location of the device) and then begins to
transmit and receive on the selected channel. The device must query
Patil, et al. Expires August 26, 2011 [Page 3]
Internet-Draft PAWS: PS and Reqmts February 2011
the database again for a list of unoccupied channels based on certain
conditions, e.g. a fixed amount of time has passed, the device has
changed location beyond a specified threshold. The basic scenario is
that before transmitting in TV white space, the device must get
permission from the database.
The low frequencies of the TV bands have good propagation
characteristics. At these low frequencies, a radio signal will
travel ~3 times further than traditional WLAN at 2.5 GHz, assuming
the same transmit power. Because of these characteristics and new
cognitive radio techniques, when TV white space is taken into use,
this will enable new use cases and new business opportunities. Not
only is the capacity of new spectrum needed, but this propagation
trait by itself makes TV white space attractive for providing BWA in
rural, sparsely populated areas, and also for extended range home
hot-spot coverage (similar to WLAN today, but with improved
coverage). In addition to propagation characteristics, the
geolocation database will provide new capabilities for devices that
use TV white space. When a device using TV white space registers its
location in the database, this simple act makes the location of the
device available for location based services.
This document discusses the requirements for accessing a database to
obtain information that enables a device to operate/use the available
channels at a given location. It also identifies various issues that
need to be addressed by the protocol between the device and database.
2. Terminology and Concepts
2.1. Terminology
TV White Space
TV white space refers specifically to radio spectrum which has
been allocated for TV broadcast, but is not occupied by a TV
broadcast, or other licensed user (such as a wireless microphone),
at a specific location and time.
White Space Device
A white space device can be an access point, base station or a
portable device. Different classes of white space devices exist.
Any device which plans to use the available spectrum to provide
service/connectivity to others is required to contact a database
to obtain information about available channels.
Patil, et al. Expires August 26, 2011 [Page 4]
Internet-Draft PAWS: PS and Reqmts February 2011
Database
In the context of white space and cognitive radio technologies,
the database is an entity which contains uptodate information
about available spectrum at any given location, registered devices
and other types of information.
Cognitive Radio
A cognitive radio uses knowledge of the local radio environment to
dynamically adapt its own configuration and function properly in a
changing radio environment. A radio which is able to dynamically
which frequency to use is one example of a cognitive radio.
2.2. The concept of Cognitive Radio
A cognitive radio uses knowledge of the local radio environment to
dynamically adapt its own configuration and function properly in a
changing radio environment. Knowledge of the local radio environment
can come from various technology enablers including location
determination and internet connectivity to a database to learn the
details of the local radio environment. Cognitive radio technology
can be used for all available portions of spectrum, even those within
bands dedicated to a Primary use like TV or satellite. TV White
Space is one implementation of cognitive radio. Because a cognitive
radio adapts itself to the available spectrum in a manner that
prevents the creation of harmful interference, the spectrum can be
shared among different radio users.
3. Background information on white space in US
Television transmission in the United States has moved to the use of
digital signals as of June 12, 2009. Since June 13, 2009, all full-
power U.S. television stations have broadcast over-the-air signals in
digital only. An important benefit of the switch to all-digital
broadcasting is that it freed up parts of the valuable broadcast
spectrum. More information about the switch to digital transmission
is at : [DTV].
With the switch to digital transmission for TV, the guard bands that
existed to protect the signals between stations can now be used for
other purposes. The FCC has made this spectrum available for
unlicensed use and this is generally refered to as white space.
Please see the details of the FCC ruling and regulations in [FCC
ruling]. The spectrum can be used to provide wireless broadband as
an example. The term "Super-Wifi" is also used to describe this
spectrum and potential for providing wifi type of service.
Patil, et al. Expires August 26, 2011 [Page 5]
Internet-Draft PAWS: PS and Reqmts February 2011
Efforts are ongoing to specify air-interfaces for use in white space
spectrum. IEEEs 802.11af task group is currently working on one such
specification. IEEE 802.22 is another example. Other air interfaces
could be specified in the future such as LTE.
4. 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/channels 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. The databases are also country specific since the
available spectrum and regulations may vary.
An example high-level architecture of the devices and white space
databases is shown in the figure below:
-----------
|WS Device| ------------
|Lat: X |\ .---. /--------|Database X|
|Long: Y | \ ( ) / ------------
----------- \-------/ \/ o
( Internet ) o
----------- /------( )\ o
|WS Device| / (_____) \ ------------
|Lat: X |/ \--------|Database Y|
|Long: Y | ------------
-----------
Figure 1: 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.
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.
Patil, et al. Expires August 26, 2011 [Page 6]
Internet-Draft PAWS: PS and Reqmts February 2011
4.1. 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. But the need for devices that intend to use the
spectrum to communicate with a regulatory database remains a common
feature.
Devices need to be able to query a database which are accessible via
the Internet prior to operating in available spectrum. Information
about available spectrum, channels, 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. 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.
3. Address regulatory requirements - Each country will likely have
regulations that are unique to that country. The messaging
interface needs to be flexible to accomodate the specific needs
of a regulatory body in the country where the white space device
is operating and connecting to the relevant database.
4.2. 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.
Patil, et al. Expires August 26, 2011 [Page 7]
Internet-Draft PAWS: PS and Reqmts February 2011
A database discovery mechanism needs to be specified. Reuse of
existing mechanisms is an option and could be adapted for meeting the
specific needs of cognitive radio technology.
4.3. 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. 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 option. The intent is
to evaluate the best option that meets the need for use between white
space devices and databases.
4.4. Security requirements
The messaging interface between the white space device and the
database needs to be secured. Both the queries and the responses
need to be delivered securely. The messages need to be protected
from eavesdropping as well as ensuring that the message content is
not modfified between the end points. The queries and responses need
to be integrity protected in addition to ciphering.
Man-in-the-middle attacks could modify the content of a response
which can cause problems for other networks or devices operating at a
given location. Interference as well as total loss of service could
result from malicious information being delivered to a white space
device.
White space devices may also be required to authenticate and register
with a database prior to using it. An authentication mechanism needs
to be specified for use in the context of this problem space.
5. IANA Considerations
This document has no requests to IANA.
6. Security Considerations
There are security aspects that need to be addressed by any solution
for the problem identified in this document. This Internet draft is
describing the requirements and problems that need to be addressed
for a messaging interface between white space devices and databases
Patil, et al. Expires August 26, 2011 [Page 8]
Internet-Draft PAWS: PS and Reqmts February 2011
and does not by itself raise any security concerns.
7. Summary and Conclusion
Cognitive radio and TV white space technology is now in the process
of being approved by regulatory bodies around the world. In the US
the FCC has already created the regulation and approved a set of
database administrators. The interface between the white space
devices and databases is over the Internet and uses IP connectivity.
The IETF can create a common standard for use on a global basis for
this interface. The IETF also has the general expertise in this area
since most of the protocols used on this Interface are ones that have
been developed in the IETF.
In summary, this document explains the requirements and issues that
need to be dealt with in specifying an interface between the white
space devices and databases. The authors strongly believe that this
interface specification should be undertaken in the IETF within the
relevant area by creating a working group.
8. Acknowledgements
The authors thank Subir Das and Tom Derryberry for their comments and
input.
9. Informative References
[DDR] Ofcom - Independent regulator and competition authority
for the UK communications industries, "Digital Dividend
Review; http://stakeholders.ofcom.org.uk/spectrum/
project-pages/ddr/".
[DTV] "Digital TV Transition; http://www.dtv.gov".
[ECC Report 159]
Electronic Communications Committee (ECC) within the
European Conference of Postal and Telecommunications
Administrations (CEPT), "TECHNICAL AND OPERATIONAL
REQUIREMENTS FOR THE POSSIBLE OPERATION OF COGNITIVE RADIO
SYSTEMS IN THE 'WHITE SPACES' OF THE FREQUENCY BAND 470-
590 MHZ; http://www.erodocdb.dk/Docs/doc98/official/pdf/
ECCREP159.PDF", January 2011.
[FCC ruling]
Federal Communications Commission, "Unlicensed Operation
Patil, et al. Expires August 26, 2011 [Page 9]
Internet-Draft PAWS: PS and Reqmts February 2011
in the TV Broadcast Bands;
http://edocket.access.gpo.gov/2010/pdf/2010-30184.pdf",
December 2010.
[Spectrum Framework Review]
Ofcom - Independent regulator and competition authority
for the UK communications industries, "Spectrum Framework
Review;
http://stakeholders.ofcom.org.uk/consultations/sfr/",
February 2005.
Authors' Addresses
Basavaraj Patil (editor)
6021 Connection drive
Irving, TX 75039
USA
Email: basavaraj.patil@nokia.com
Scott Probasco
Nokia
6021 Connection drive
Irving, TX 75039
USA
Email: scott.probasco@nokia.com
Gabor Bajko
Nokia
323 Fairchild drive 6
Mountain view, CA 94043
USA
Email: gabor.bajko@nokia.com
Patil, et al. Expires August 26, 2011 [Page 10]