Working Group Draft S. Probasco, Ed.
Internet-Draft G. Bajko
Intended status: Informational B. Patil
Expires: February 23, 2012 Nokia
B. Rosen
Neustar
August 22, 2011
Protocol to Access White Space database: PS, use cases and rqmts
draft-probasco-paws-problem-stmt-usecases-rqmts-00
Abstract
Portions of the radio spectrum that are allocated to a licensed,
primary user but are unused or unoccupied at specific locations and
times are defined as "white space". The concept of allowing
secondary transmissions (licensed or unlicensed) in white space is a
technique to "unlock" existing spectrum for new use. An obvious
requirement is that these secondary transmissions do not interfere
with the primary use of the spectrum. One approach to using the
white space spectrum at a given time and location is to verify with a
database available channels.
This document describes the concept of TV White Spaces. It also
describes the problems that need to be addressed for enabling the use
of the primary user owned white space spectrum for secondary users,
without causing interference, by querying a database which knows the
channel availability at any given location and time. A number of
possible use cases of this spectrum and derived requirements are also
described.
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
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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 February 23, 2012.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 5
2.1. Conventions Used in This Document . . . . . . . . . . . . 5
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
3. Prior Work . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. The concept of Cognitive Radio . . . . . . . . . . . . . . 6
3.2. Background information on white space in US . . . . . . . 6
3.3. Air Interfaces . . . . . . . . . . . . . . . . . . . . . . 7
4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Global applicability . . . . . . . . . . . . . . . . . . . 8
4.2. Database discovery . . . . . . . . . . . . . . . . . . . . 9
4.3. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.4. Data model definition . . . . . . . . . . . . . . . . . . 10
5. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. TVWS database discovery . . . . . . . . . . . . . . . . . 10
5.2. Hotspot: urban internet connectivity service . . . . . . . 11
5.3. Wide-Area or Rural internet broadband access . . . . . . . 13
5.4. Offloading: moving traffic to a white space network . . . 15
5.5. TVWS for backhaul . . . . . . . . . . . . . . . . . . . . 17
5.6. Location based service usage scenario . . . . . . . . . . 18
6. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 20
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8. Security Considerations . . . . . . . . . . . . . . . . . . . 20
9. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 20
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10.1. Normative References . . . . . . . . . . . . . . . . . . . 21
10.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
Wireless spectrum is a commodity that is regulated by governments.
The spectrum is used for various purposes, which include
entertainment (e.g. radio and television), communication (telephony
and Internet access), military (radars etc.) and, navigation
(satellite communication, GPS). Portions of the radio spectrum that
are allocated to a licensed, primary user but are unused or
unoccupied at specific locations and times are defined as "white
space". The concept of allowing secondary transmissions (licensed or
unlicensed) in white space is a technique to "unlock" existing
spectrum for new use. An obvious requirement is that these secondary
transmissions do not interfere with the primary use of the spectrum.
One interesting observation is that often, in a given physical
location, the primary user(s) may not be using the entire band
allocated to them. The available spectrum for a secondary use would
then depend on the location of the secondary user. The fundamental
issue is how to determine for a specific location and specific time,
if any of the primary spectrum is available for secondary use.
Academia and Industry have studied multiple cognitive radio
mechanisms for use in such a scenario. One simple mechanism is to
use a geospatial database that records the primary users occupation,
and require the secondary users to check the database prior to
selecting what part of the spectrum they use. Such databases could
be available on the Internet for query by secondary users.
Spectrum useable for data communications, especially wireless
Internet communications, is scarce. 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 a given area. In 2008 the
United States regulator (the FCC) took initial steps when they
published their first ruling on the use of TV white space, and then
followed it 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. More countries are expected to provide
access to their TV spectrum in similar ways. Any entity holding
spectrum that is not densely used may be asked to give it up in one
way or another for more intensive use. Providing a mechanism by
which secondary users share the spectrum with the primary user is
attractive in many bands in many countries.
Television transmission until now has primarily been analog. The
switch to digital transmission has begun. As a result the spectrum
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allocated for television transmission can now be more effectively
used. Unused channels and bands between channels can be used as long
as they do not interfere with the primary service for which that
channel is allocated. While urban areas tend to have dense usage of
spectrum and a number of TV channels, the same is not true in rural
and semi- urban areas. There can be a number of unused TV channels
in such areas that can be used for other services. The figure below
shows TV white space within the lower UHF band:
Avg |
usage| |-------------- White Space
| | | | | |
0.6| || || V V ||
| || ||| | ||
0.4| || |||| | ||
| || |||| | ||<----TV transmission
0.2| || |||| | ||
|----------------------------------------
400 500 600 700 800
Frequency in MHz ->
Figure 1: High level view of TV White Space
The fundamental issue is how to determine for a specific location and
specific time if any of the spectrum is available for secondary use.
There are two dimensions of use that may be interesting: space (the
area in which a secondary user would not interfere with a primary
user, and time: when the secondary use would not interfere with the
primary use. In this discussion, we consider the time element to be
relatively long term (hours in a day) rather than short term
(fractions of a second). Location in this discussion is geolocation:
where the transmitters (and sometimes receivers) are located relative
to one another. In operation, the database records the existing
user's transmitter (and some times receiver) locations along with
basic transmission characteristics such as antenna height, and
sometimes power. Using rules established by the regulator, the
database calculates an exclusion zone for each authorized primary
user, and attaches a time schedule to that use. The secondary user
queries the database with it location. The database intersects the
exclusion zones with the queried location, and returns the portion of
the spectrum not in any exclusion zone. Such methods of geospatial
database query to avoid interference have been shown to achieve
favorable results, and are thus the basis for rulings by the FCC and
reports from ECC and Ofcom. In any country, the rules for which
primary entities are entitled to protection, how the exclusion zones
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are calculated, and what the limits of use by secondary entities are
may vary. However, the fundamental notion of recording primary
users, calculating exclusion zones, querying by location and
returning available spectrum (and the schedule for that spectrum) are
common
This document includes the problem statement, use cases and
requirements associated with the use of white space spectrum by
secondary users via a database query protocol.
2. Conventions and Terminology
2.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2.2. Terminology
Database
In the context of white space and cognitive radio technologies,
the database is an entity which contains current information about
available spectrum at any given location and other types of
information.
Location Based Service
An application or device which provides data, information or
service to a user based on their location.
Master Device
A device which queries the WS Database to find out the available
operating channels.
Protected Entity
A primary user of white space spectrum which is afforded
protection against interference by secondary users (white space
devices) for its use in a given area and time.
Protected Contour
The exclusion area for a Protected Entity, held in the database
and expressed as a polygon with geospatial points as the vertices.
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Slave Device
A device which uses the spectrum made available by a master
device.
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
Radio spectrum which has been allocated for some primary use, but
is not fully occupied by that primary use at a specific location
and time.
White Space Device
A device which is a secondary user of some part of white space
spectrum. A white space device can be an access point, base
station, a portable device or similar. In this context, a white
space device is required to query a database with its location to
obtain information about available spectrum.
3. Prior Work
3.1. 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 mechanisms including sensing
(attempting to ascertain primary users by listening for them within
the spectrum), location determination and internet connectivity to a
database to learn the details of the local radio environment. 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.
3.2. 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
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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 referred 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.
3.3. Air Interfaces
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 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 2: 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.
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. 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.
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.
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4.3. 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.
4.4. 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.
5. Use cases
There are many potential use cases that could be considered for the
TV white space spectrum. Providing broadband internet access in
hotspots, rural and underserved areas are examples. Available
channels may also be used to provide internet 'backhaul' for
traditional Wi-Fi hotspots, or by towns and cities to monitor/control
traffic lights or read utility meters. Still other use cases include
the ability to offload data traffic from another internet access
network (e.g. 3G cellular network) or to deliver location based
services. Some of these use cases are described in the following
sections.
5.1. TVWS database discovery
This use case is preliminary to creating a radio network using TV
white space; it is a prerequisite to other use cases. The radio
network is created by a master device which can be an access point
that establishes Hotspot coverage, a base station that establish
cellular coverage, or a device that establishes a peer-to-peer or ad-
hoc network. Before the master device can transmit in TV white space
spectrum, it must contact a trusted database where the device can
learn if any channels are available for it to use.
In the simplest case the radio device is pre-programmed with the
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internet address of at least one trusted database. The device can
establish contact with a trusted database using one of the pre-
programmed internet addresses and establish a TV white space network
(as described in one of the following use cases).
If the radio device (master) does not have a pre-programmed address
for a trusted white space database, or if the trusted database at the
pre-programmed address is not responsive, or perhaps the trusted
database does not provide service for the radio device's current
location, or at the user's choice, the device may attempt to
"discover" a trusted database which provides service at the current
location.
1. The master is connected to the internet by any means other than
using the TV white space radio.
2. The master constructs and broadcasts a query message over the
internet and waits for responses.
3. If no acceptable response is received within a pre-configured
time limit, the device concludes that no trusted database is
available. If one or more response is received, the device
evaluates the response to determine if a trusted database can be
identified where the device is able to register and receive
service from the database.
5.2. Hotspot: urban internet connectivity service
In this use case internet connectivity service is provided in a
"hotspot" to local users. Typical deployment scenarios include urban
areas where internet connectivity is provided to local businesses and
residents, and campus environments where internet connectivity is
provided to local buildings and relatively small outdoor areas. This
deployment scenario is typically characterized by multiple masters
(APs or hotspots) in close proximity, with low antenna height, cells
with relatively small radius (a few kilometers or less), and limited
numbers of available radio channels. Many of the masters/APs are
assumed to be individually deployed and operated, i.e. there is no
coordination between many of the masters/APs. The masters/APs in
this scenario use a TDD radio technology and transmit at or below a
relatively low transmit power threshold. Each master/AP has a
connection to the internet and provides internet connectivity to
multiple end user or slave devices.
The figure below shows an example deployment of this scenario.
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-------
|Slave|\ \|/ ----------
|Dev 1| (TDD AirIF) | |Database|
------- \ | .---. /---------
o \ |-|---------| ( ) /
o | Master | / \
o / | |========( Internet )
o / |-----------| \ /
------- (TDD AirIF) ( )
|Slave| / (----)
|Dev n|
-------
Figure 3: Hotspot service using TV white space spectrum
Once a master/AP has been correctly installed and configured, a
simplified power up and operation scenario utilizing TV White Space
to provide Internet connectivity service consists of the following
steps:
1. The master/AP powers up; however its WS radio and all other WS
capable devices will power up in idle/listen only mode (no active
transmissions on the WS frequency band).
2. The master/AP has Internet connectivity and establishes a
connection to a trusted white space database (see use case "TVWS
database discovery" above).
3. The master/AP registers its geolocation, address, contact
information, etc. associated with the owner/operator of the
master/AP with the trusted database administrator (if not
currently registered). Depending upon local regulator policy,
the DB administrator may be required to store and forward the
registration information to the regulatory authority.
4. Following the registration process, the master/AP will send a
query to the trusted database requesting a list of available WS
channels based upon its geolocation.
5. If the master/AP has been previously authenticated, the database
responds with a list of available white space channels that the
master may use, and optionally a duration of time for their use.
6. Once the master/AP authenticates the WS channel list response
message from the database, the AP selects an available WS
channel(s) from the list.
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7. The master/AP acknowledges to the database which of the available
WS channels it has selected for its operation. The database is
updated with the information provided by the master/AP.
8. The slave or user device scans the TV bands to locate a master/AP
transmission, and associates with the AP. The slave/user device
queries the master for a channel list, based on the slaves'
geolocation.
9. The master provides the list of channels locally available to the
slave/user device. If the channel that the user terminal is
currently using is not included in the list of locally available
channels, the slave/user device ceases all operation on its
current channel. The slave/user device may scan for another AP
transmission on a different channel.
5.3. Wide-Area or Rural internet broadband access
In this use case internet broadband access is provided as a Wide-Area
Network (WAN) or Wireless Regional Area Network (WRAN). A typical
deployment scenario is a wide area or rural area, where internet
broadband access is provided to local businesses and residents from a
master (i.e. BS) connected to the internet. This deployment
scenario is typically characterized by one or more fixed master(s)/
BS(s), cells with relatively large radius (tens kilometers up to 100
km), and many available radio channels. Many of the masters/BSs are
assumed to be deployed and operated by a single entity, i.e. there is
coordination between many of the masters/BSs. The BS in this
scenario use a TDD radio technology and transmit at or below a
transmit power threshold established by the local regulator. Each
base station has a connection to the internet and provides internet
connectivity to multiple slave/end-user devices. End user terminals
or devices may be fixed or portable.
The figure below shows an example deployment of this scenario.
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-------
|Slave|\ \|/ ----------
|Dev 1| (TDD AirIF) | |Database|
------- \ | .---. /----------
o \ |-|---------| ( ) /
o | Master | / \
o / | (BS) |========( Internet )
o / |-----------| \ /
------- (TDD AirIF) ( )
|Slave| / (----)
|Dev n|
-------
Figure 4: Rural internet broadband access using TV white space
spectrum
Once the master/BS has been professionally installed and configured,
a simplified power up and operation scenario utilizing TV White Space
to provide rural internet broadband access consists of the following
steps:
1. The master/BS powers up; however its WS radio and all other WS
capable devices will power up in idle/listen only mode (No active
transmissions on the WS frequency band)
2. The master/BS has internet connectivity and establishes a
connection to a trusted white space database (see use case "TVWS
database discovery" above).
3. The master/BS registers its geolocation, address, contact
information, etc. associated with the owner/operator of the
master/BS with the trusted database service (if not currently
registered). Meanwhile the DB administrator may be required to
store and forward the registration information to the regulatory
authority. If a trusted white space database administrator is
not discovered, further operation of the WRAN may be allowed
according to local regulator policy (in this case operation of
the WRAN is outside the scope of the PAWS protocol).
4. Following the registration process, the master/BS will send a
query to the trusted database requesting a list of available WS
channels based upon its geolocation.
5. If the master/BS has been previously authenticated, the database
responds with a list of available white space channels that may
be used and optionally a maximum transmit power (EIRP) for each
channel and a duration of time the channel may be used.
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6. Once the master/BS authenticates the WS channel list response
message from the database, the master/BS selects an available WS
channel(s) from the list. The operator may disallow some
channels from the list to suit local needs if required.
7. The master/BS acknowledges to the database which of the available
WS channels the BS has selected for its operation. The database
is updated with the information provided by the BS.
8. The slave or user device scans the TV bands to locate a WRAN
transmission, and associates with the master/BS. The slave/user
device queries the master for a channel list, based on the
slaves' geolocation.
9. The master provides the list of channels locally available to the
slave/user device. If the channel that the user terminal is
currently using is not included in the list of locally available
channels, the slave/user device ceases all operation on its
current channel. The slave/user device may scan for another WRAN
transmission on a different channel.
5.4. Offloading: moving traffic to a white space network
In this use case internet connectivity service is provided over TV
white space as a supplemental or alternative datapath to a 3G or
other internet connection. In a typical deployment scenario an end
user has a primary internet connection such as a 3G cellular packet
data subscription. The user wants to use a widget or application to
stream video from an online service (e.g. youtube) to their device.
Before the widget starts the streaming connection it checks
connectivity options available at the current time and location.
Both 3G cellular data is available as well as TVWS connectivity (the
user is within coverage of a TVWS master -- hotspot, WAN, WRAN or
similar). The user may decide for many and various reasons such as
cost, RF coverage, data caps, etc. to prefer the TVWS connection over
the 3G cellular data connection. Either by user selection,
preconfigured preferences, or other algorithm, the streaming session
is started over the TVWS internet connection instead of the 3G
cellular connection. This deployment scenario is typically
characterized by a TVWS master/AP providing local coverage in the
same geographical area as a 3G cellular system. The master/AP is
assumed to be individually deployed and operated, i.e. the master/AP
is deployed and operated by the user at his home or perhaps by a
small business such as a coffee shop. The master/AP has a connection
to the internet and provides internet connectivity to the slave/
end-user's device.
The figure below shows an example deployment of this scenario.
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\|/
|
|
|-|---------|
| Master/AP |\
/| Router | \
Streaming/ |-----------| \
-------- / \ -----------
|Slave/| / \ (----) | Database |
|WS Dev| \ ( ) /----------
------- \ \ / \
\ X( Internet )
\ / \ /
Signaling \|/ / ( )\
\ | / (----) \----------
\ | / | YouTube |
\|-|---------| / ----------
| Master / | /
| 3G BTS |/
|-----------|
Figure 5: Offloading: moving traffic to a white space network
Once a dual or multi mode device (3G + TVWS) is connected to a 3G
network, a simplified operation scenario of offloading selected
content such as video stream from the 3G connection to the TWVS
connection consists of the following steps:
1. The dual mode (or multi mode) device (3G + TVWS) is connected to
a 3G network. The device has contacted a trusted database to
discover the list of available TV channels at is current
location. The device has located a TVWS master/AP operating on
an available channel and has associated or connected with the
TVWS master/AP.
2. The user activates a widget or application that streams video
from YouTube. The widget connects to YouTube over 3G cellular
data. The user browses content and searches for video
selections.
3. The user selects a video for streaming using the widget's
controls. Before the widget initiates a streaming session, the
widget checks the available connections in the dual mode device
and finds a TVWS master/AP is connected.
4. Using either input from the user or pre-defined profile
preferences, the widget selects the TVWS master/AP as the
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connection to stream the video.
5.5. TVWS for backhaul
In this use case internet connectivity service is provided to users
over a traditional wireless protocol, one common example is Wi-Fi.
The TV white space network provides the "backhaul" or connection from
the Wi-Fi to the internet. In a typical deployment scenario an end
user has a device with a radio such as Wi-Fi. A service provider or
shop owner wants to provide Wi-Fi internet service for their
customers. The location where the service provider wants to provide
Wi-Fi is within range of a TVWS master (e.g. Hotspot or Wide-Area/
Rural network). The service provider installs a TVWS slave device
and connect this slave to a Wi-Fi access point. This deployment
scenario is typically characterized by a TVWS master/AP/BS providing
local coverage. The master/AP has a connection to the internet and
provides internet connectivity to the slave device. The slave device
is then 'bridged' to a Wi-Fi network
The figure below shows an example deployment of this scenario.
\|/ white \|/ \|/ WiFi \|/
| space | | |
| | | |-|----|
|--------| |-|---------| |-|------|-| | WiFi |
| | | Master | | Slave | | Dev |
|internet|------| (AP/BS) | | Bridge | |------|
| | | | | to WiFi |
|--------| |-----------| |----------| \|/
|
|-|----|
| WiFi |
| Dev |
|------|
Figure 6: TVWS for backhaul
Once the bridged device (TVWS+WiFi) is connected to a master and TVWS
network, a simplified operation scenario of backhaul for WiFi
consists of the following steps:
1. A bridged device (TVWS+WiFi) is connected to a master device
operating in the TVWS. The bridged device operates as a slave
device in either Hotspot or Wide-Area/Rural internet use cases
described above.
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2. Once the slave device is connected to the master, the Wi-Fi
access point configures its internet settings automatically based
on the backhaul connection (i.e. it uses DHCP).
3. End users connect their WiFi device to the bridged device and
receive internet connectivity.
5.6. Location based service usage scenario
The owner of a shopping mall wants to provide internet access to
customers when they are at the shopping mall. His internet service
provider (ISP) recommends using master/AP devices in the TV white
space frequency band since these radios will have good propagation
characteristics, and thus will require fewer devices, and also
because the frequency band used by traditional Wi-Fi is crowded with
users such as individual stores operating their own Wi-Fi network and
also Bluetooth devices. The ISP installs APs in each large store in
the mall, and several other APs throughout the mall building. For
each AP, the professional installer programs the location (latitude
and longitude) of the device. Special tools are required to
determine the location, since typical GPS receivers do not function
indoors. When each AP is powered on, the radio does not transmit
initially. The AP contacts a white space database, using its wired
internet connection, via a URL and provides its programmed location
coordinates plus other information required by the database. A reply
is received by the AP from the database containing a list of
available channels where the AP can operate its transmitter. The AP
selects a channel for operation and notifies the database, which
records information about the AP including the identity of the AP and
its location coordinates. The AP activates its radio and begins to
function as a typical wireless AP, providing internet access to
connected devices.
A user has a slave device that is capable of operating in the TV
white spaces frequency band. A typical device would be a smartphone
with multiple radios, including a cellular radio, a Wi-Fi radio, and
TV white space radio. The user arrives at the shopping mall and
enters the building. The white space radio in the smartphone is on,
and is scanning for a master/AP. As the user gets near the entrance
to the shopping mall, the smartphone locates one of the APs in the
building and connects to it. The smartphone begins to use this TVWS
radio for internet access. This internet access does not count
against the users cellular data cap (the mall owner is providing the
internet access) and also the data rates are better than cellular
data. As the user walks throughout the mall the smartphone moves
between coverage of different APs, and the smartphone connects to a
new AP when the user and smartphone move near it.
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In order to encourage customers to come to the shopping mall, the
mall owner has a loyalty program where members register, build
points, and receive coupons and other notices from the shops in the
mall. Before installing the internet service in the mall, all
loyalty program information was mailed to the user, at an address
which was provided by the user when joining the loyalty program.
The ISP provider describes to the mall owner how the loyalty program
can be improved using the internet service provided by the APs in the
TV white space. A new app is developed for this loyalty program, and
promoted to users, asking them to install the app on their
smartphone. The app is provisioned with the user's loyalty program
information. When the user comes to the shopping mall, the
smartphone locates the master/AP providing internet service and
connects to the AP. The app in the smartphone sees that a radio
connection to an AP in the TV white space frequency band is now
active. The app registers the identity of the AP and forwards this
to the home server for the loyalty program, using the internet
connection provided by the AP in the TV white space band. The
loyalty program server registers the identity of the user from the
loyalty program credentials and also the identity of the AP. Next
the loyalty program server contacts the TV white space database and
requests the location of the master/AP having the identity forwarded
by the app and smartphone. When the TV white space database replies
with the location coordinates of the AP, the loyalty program server
knows the approximate location of the user and smartphone. With this
location information, the loyalty program server can now forward
loyalty program information to the user. As the user moves through
the mall, the smartphone connects to different APs. The process is
repeated, allowing the loyalty program to delivery current location
based information to the user.
1. The master create a TVWS network as described in use case
"Hotspot: urban internet connectivity service."
2. An application running on the user's slave device (e.g.
smartphone) determines that a network connection exists in the
TVWS band. The identify of the master/AP is recorded by the
application and forwarded to a server in the internet cloud.
3. The server queries the trusted white space database with the
master identity provided by the application in the user's
smartphone.
4. The trusted white space database replies to the server with the
location of the master device.
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5. The server uses the location of the master/AP to determine the
approximate location of the user's smartphone. The server
provides location-specific service to the user via the
application running in the smartphone.
6. Requirements
This section is the placeholder for the requirements derived from the
use cases.
7. IANA Considerations
This document has no requests to IANA.
8. Security Considerations
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 device must be certain it is
talking to a bona fide database authoritative for the location and
spectrum band the device operates on. The database may need to
restrict interactions to devices that it has some prior relationship
with, or may be restricted from providing service to devices that are
not authorized in some manner.
As the device will query with it's location, the location must be
protected against eavesdropping. Some regulations include personally
identifiable information as required elements of registration and/or
query and must similarly be protected.
All communications between the device and the database will require
integrity protection.
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.
9. Summary and Conclusion
Wireless spectrum is a scarce resource. As the demand for spectrum
grows, there is a need to more efficiently utilize the available and
allocated spectrum. Cognitive radio technologies enable the
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efficient usage of spectrum via means such as sensing or by querying
a database to determine available spectrum at a given location for
secondary use. White space is the general term used to refer to the
bands within the spectrum which is available for secondary use at a
given location. In order to use this spectrum a device needs to
query a database which maintains information about the available
channels within a band. A protocol is necessary for communication
between the devices and databases which would be globally applicable.
The document describes some examples of the role of the white space
database in the operation of a radio network and also shows an
examples of a services provided to the user of a TVWS device. From
these use cases requirements are determined. These requirements are
to be used as input to the definition of a Protocol to Access White
Space database (PAWS).
10. References
10.1. Normative References
[PAWS-PS] IETF, "Protocol to Access White Space database: Problem
statement; https://datatracker.ietf.org/doc/
draft-patil-paws-problem-stmt/", July 2011.
[RFC2119] IETF, "Key words for use in RFCs to Indicate Requirement
Levels;
http://www.rfc-editor.org/rfc/pdfrfc/rfc2119.txt.pdf",
March 1997.
10.2. 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.
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[FCC Ruling]
FCC, "Federal Communications Commission, "Unlicensed
Operation in the TV Broadcast Bands;
http://edocket.access.gpo.gov/2010/pdf/2010-30184.pdf"",
December 2010.
[RFC5222] IETF, Hardie, T., Netwon, A., Schulzrinne, H., and H.
Tschofenig, "LoST: A Location-to-Service Translation Proto
col;http://www.rfc-editor.org/rfc/pdfrfc/rfc5222.txt.pdf",
August 2008.
[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.
[TV Whitespace Tutorial Intro]
IEEE 802 Executive Committee Study Group on TV White
Spaces, "TV Whitespace Tutorial Intro; http://
grouper.ieee.org/groups/802/802_tutorials/2009-03/
2009-03-10%20TV%20Whitespace%20Tutorial%20r0.pdf",
March 2009.
Authors' Addresses
Scott Probasco (editor)
Nokia
6021 Connection drive
Irving, TX 75039
USA
Email: scott.probasco@nokia.com
Gabor Bajko
Nokia
200 South Mathilda Ave
Sunnyvale, CA 94086
USA
Email: gabor.bajko@nokia.com
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Basavaraj Patil
Nokia
6021 Connection drive
Irving, TX 75039
USA
Email: basavaraj.patil@nokia.com
Brian Rosen
Neustar
470 Conrad Dr
Mars, PA 16046
USA
Email: brian.rosen@neustar.biz
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