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Versions: (draft-probasco-paws-problem-stmt-usecases-rqmts) 00 01 02 03 04 05 06 07 08 09 10 11 12 15 RFC 6953

Working Group Draft                                     S. Probasco, Ed.
Internet-Draft                                                  B. Patil
Intended status: Informational                                     Nokia
Expires: January 3, 2013                                    July 2, 2012


    Protocol to Access White Space database: PS, use cases and rqmts
             draft-ietf-paws-problem-stmt-usecases-rqmts-06

Abstract

   Portions of the radio spectrum that are assigned to a particular use
   but are unused or unoccupied at specific locations and times are
   defined as "white space".  The concept of allowing additional
   transmissions (which may or may not be licensed) in white space is a
   technique to "unlock" existing spectrum for new use.  An obvious
   requirement is that these additional transmissions do not interfere
   with the assigned use of the spectrum.  One approach to using the
   white space spectrum at a given time and location is to verify with a
   database for available channels.

   This document describes a number of possible use cases of white space
   spectrum and technology as well as a set of requirements for the
   database query protocol.  The concept of TV white spaces is described
   including the problems that need to be addressed to enable white
   space spectrum for additional uses without causing interference to
   currently assigned use.  Use of white space is enabled by querying a
   database which stores information about the channel availability at
   any given location and time.

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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   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 January 3, 2013.

Copyright Notice



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   Copyright (c) 2012 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
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   described in the Simplified BSD License.







































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Introduction to white space  . . . . . . . . . . . . . . .  4
     1.2.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
       1.2.1.  In Scope . . . . . . . . . . . . . . . . . . . . . . .  6
       1.2.2.  Out of Scope . . . . . . . . . . . . . . . . . . . . .  6
   2.  Conventions and Terminology  . . . . . . . . . . . . . . . . .  7
     2.1.  Conventions Used in This Document  . . . . . . . . . . . .  7
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  7
   3.  Prior Work . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     3.1.  The concept of Cognitive Radio . . . . . . . . . . . . . .  8
     3.2.  Background information on white space in the US  . . . . .  9
     3.3.  Background information on white space in the UK  . . . . .  9
     3.4.  Air Interfaces . . . . . . . . . . . . . . . . . . . . . . 10
   4.  Use cases and protocol services  . . . . . . . . . . . . . . . 10
     4.1.  Protocol services  . . . . . . . . . . . . . . . . . . . . 10
       4.1.1.  White space database discovery . . . . . . . . . . . . 10
       4.1.2.  Device registration with trusted Database  . . . . . . 11
     4.2.  Use cases  . . . . . . . . . . . . . . . . . . . . . . . . 12
       4.2.1.  Hotspot: urban Internet connectivity service . . . . . 12
       4.2.2.  Wide-Area or Rural Internet broadband access . . . . . 15
       4.2.3.  Offloading: moving traffic to a white space network  . 18
       4.2.4.  White space serving as backhaul  . . . . . . . . . . . 20
       4.2.5.  Rapid deployed network for emergency scenario  . . . . 21
       4.2.6.  Mobility . . . . . . . . . . . . . . . . . . . . . . . 22
       4.2.7.  Indoor Networking  . . . . . . . . . . . . . . . . . . 25
       4.2.8.  Machine to Machine (M2M) . . . . . . . . . . . . . . . 26
   5.  Problem Statement  . . . . . . . . . . . . . . . . . . . . . . 28
     5.1.  Global applicability . . . . . . . . . . . . . . . . . . . 29
     5.2.  Database discovery . . . . . . . . . . . . . . . . . . . . 30
     5.3.  Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 31
     5.4.  Data model definition  . . . . . . . . . . . . . . . . . . 31
   6.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 31
     6.1.  Normative Requirements . . . . . . . . . . . . . . . . . . 31
     6.2.  Non-normative requirements . . . . . . . . . . . . . . . . 34
     6.3.  Guidelines . . . . . . . . . . . . . . . . . . . . . . . . 36
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 37
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 37
   9.  Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 40
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 40
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 40
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 40
     11.2. Informative References . . . . . . . . . . . . . . . . . . 41
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 42






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1.  Introduction

1.1.  Introduction to white space

   Wireless spectrum is a commodity that is regulated by governments.
   The spectrum is used for various purposes, which include but are not
   limited to entertainment (e.g. radio and television), communication
   (e.g. telephony and Internet access), military (e.g. radars etc.)
   and, navigation (e.g. satellite communication, GPS).  Portions of the
   radio spectrum that are assigned to a licensed user but are unused or
   unoccupied at specific locations and times are defined as "white
   space".  The concept of allowing additional transmissions (which may
   or may not be licensed) in white space is a technique to "unlock"
   existing spectrum for new use.  An obvious requirement is that these
   additional transmissions do not interfere with the assigned use of
   the spectrum.  One interesting observation is that often, in a given
   physical location, the assigned user(s) may not be using the entire
   band assigned to them.  The available spectrum for additional
   transmissions would then depend on the location of the additional
   user.  The fundamental issue is how to determine for a specific
   location and specific time, if any of the assigned spectrum is
   available for additional 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
   assigned users occupation, and require the additional 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
   additional 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 ruling in 2010 [FCC Ruling] that established
   the basic foundation for TV white space service in the US.  In May
   2012 the FCC issued minor updates further refining the previous
   ruling [3MOO].  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, with proposals from 2009
   onwards to access TV white space, leading to the 2011 Ofcom Statement
   Implementing Geolocation [Ofcom Implementing] which has been followed
   by draft requirements for TV white space devices [Ofcom
   Requirements].  More countries are expected to provide access to



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   their TV spectrum in similar ways.  Any entity that is assigned
   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 additional users share the spectrum with the assigned 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
   assigned for television transmission can now be more effectively
   used.  Unused channels and bands between channels can be used by
   additional users as long as they do not interfere with the service
   for which that channel is assigned.  While urban areas tend to have
   dense usage of spectrum and a number of TV channels, the same is not
   true in semi-rural, rural and remote areas.  There can be a number of
   unused TV channels in such areas that can be used for other services.
   Figure 1 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 additional use.
   There are two dimensions of use that may be interesting: space (the
   area in which an additional user would not interfere with the
   assigned use), and time: when the additional transmission would not
   interfere with the assigned use.  In this discussion, we consider the
   time element to be relatively long term (e.g. hours in a day) rather
   than short term (e.g. 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 assigned user's transmitter (and some times
   receiver) locations along with basic transmission characteristics
   such as antenna height, and power.  Using rules established by the
   local regulator, the database calculates an exclusion zone for each



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   assigned user, and attaches a time schedule to that use.  The
   additional user queries the database with its 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 assigned entities are entitled to protection, how the exclusion
   zones are calculated, and what the limits of use are by additional
   users may vary.  However, the fundamental notion of recording
   assigned 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.

1.2.  Scope

1.2.1.  In Scope

   This document applies only to communications required for basic
   service in TV white spaces.  The protocol will enable a white space
   radio device to complete the following tasks:

   1.  Determine the relevant white space database to query.

   2.  Connect to the database using a well-defined access method.

   3.  Register with the database using a well-defined protocol.

   4.  Provide its geolocation and perhaps other data to the database
       using a well-defined format for querying the database.

   5.  Receive in response to the query a list of currently available
       white space channels or frequencies using a well-defined format
       for the information.

   6.  Send an acknowledgment to the database with information
       containing channels selected for use by the device.

1.2.2.  Out of Scope

   The following topics are out of scope for this specification:

      Co-existence and interference avoidance of white space devices
      within the same spectrum



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      Provisioning (releasing new spectrum for white space use)


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, but is not limited to,
      current information as required by by the regulatory policies
      about available spectrum at any given location and time, and other
      types of related (to the white space spectrum) or relevant
      information.

   Device Class

      Identifies classes of devices defined by Regional Regulators,
      including fixed, mobile, portable, etc...  May also indicate if
      the device is indoor or outdoor.

   Device ID

      A unique number for each master device and slave device that
      identifies the manufacturer, model number and serial number.

   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

      An assigned user of white space spectrum which is afforded
      protection against interference by additional users (white space
      devices) for its use in a given area and time.



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   Protected Contour

      The exclusion area for a Protected Entity, held in the database
      and expressed as a polygon with geospatial points as the vertices.

   Slave Device

      A device which uses the spectrum made available by a master
      device, and cannot query the database directly.

   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 assigned user (such as a wireless microphone),
      at a specific location and time.

   TV White Space Device (TVWSD)

      A White Space Device that operates in the TV bands.

   White Space (WS)

      Radio spectrum which is not fully occupied at a specific location
      and time.

   White Space Device (WSD)

      A device which opportunistically uses some part of white space
      spectrum.  A white space device can be an access point, base
      station, a portable device or similar.  A white space device may
      be required by local regulations 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.  White
   Space is one implementation of cognitive radio.  Because a cognitive
   radio adapts itself to the available spectrum in a manner that



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   prevents the creation of harmful interference, the spectrum can be
   shared among different radio users.

3.2.  Background information on white space in the 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].

   Besides the switch to digital transmission for TV, the guard bands
   that exist to protect the signals between stations can 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.

3.3.  Background information on white space in the UK

   Background information on white space in UK Since its launch in 2005,
   Ofcom's Digital Dividend Review [DDR] has considered how to make the
   spectrum freed up by digital switchover available for new uses,
   including the capacity available within the spectrum that is retained
   to carry the digital terrestrial television service.  Similarly to
   the US, this interleaved or guard spectrum occurs because not all the
   spectrum in any particular location will be used for terrestrial
   television and so is available for other services, as long as they
   can interleave their usage around the existing users.

   In its September 2011 Statement [Ofcom Implementing] Ofcom says that
   a key element in enabling white space usage in the TV bands is the
   definition and provision of a database which, given a device's
   location, can tell the device which frequency channels and power
   levels it is able to use without causing harmful interference to
   other licensed users in the vicinity.  Ofcom will specify
   requirements to be met by such geolocation databases.  It also says
   that the technology has the possibility of being usefully applied
   elsewhere in the radio spectrum to ensure it is used to maximum
   benefit.  For example, it may have potential in making spectrum
   available for new uses following any switch to digital radio
   services.  Alternatively it may be helpful in exploiting some of the
   public sector spectrum holdings.  Ofcom will continue to consider
   other areas of the radio spectrum where white space usage may be of
   benefit.



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3.4.  Air Interfaces

   Efforts are ongoing to specify air-interfaces for use in white space
   spectrum.  IEEE 802.11af, IEEE 802.15.4m and IEEE 802.22 are all
   examples.  Other air interfaces could be specified in the future such
   as LTE.


4.  Use cases and protocol services

   There are many potential use cases that could be considered for the
   TV white space spectrum.  Providing broadband Internet access in
   urban and densely populated 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.

4.1.  Protocol services

   A complete protocol solution must provide all services that are
   essential to enable the white space paradigm.  Before a white space
   device can begin operating it needs to know what channels are
   available by sending a query to a white space database for a list of
   available channels, the white space device must have the capability
   to first locate or "discover" a suitable database.  Additionally,
   some regulatory authorities require the white space device to
   register with the database as a first step.  This section describes
   the features required from the protocol.

4.1.1.  White space database discovery

   White space database discovery is preliminary to creating a radio
   network using white space; it is a prerequisite to the use cases
   below.  The radio network is created by a master device.  Before the
   master device can transmit in white space spectrum, it must contact a
   trusted database where the device can learn if any channels are
   available for it to use.  The master device will need to discover a
   trusted database in the relevant regulatory domain, using the
   following steps:

   1.  The master device is connected to the Internet by any means other
       than using the white space radio.  A local regulator may identify
       exception cases where a master may initialize over white space
       (e.g. the FCC allows a master to initialize over the TV white



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       space in certain conditions).

   2.  The master device constructs and sends a service request over the
       Internet to discover availability of trusted databases in the
       local regulatory domain and waits for responses.

   3.  If no acceptable response is received within a pre-configured
       time limit, the master device concludes that no trusted database
       is available.  If at least one response is received, the master
       device evaluates the response(s) to determine if a trusted
       database can be identified where the master device is able to
       receive service from the database.

   Optionally the radio device is pre-programmed with the 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 white space network (as described
   in one of the following use cases).

   Optionally the initial query will be made to a listing approved by
   the national regulator for the domain of operation (e.g. a website
   either hosted by or under control of the national regulator) which
   maintains a list of WS databases and their Internet addresses.  The
   query results in the list of databases and their Internet addresses
   being sent to the master, which then evaluates the response to
   determine if a trusted database can be identified where the master
   device is able to register and receive service from the database.

4.1.2.  Device registration with trusted Database

   Registration may be preliminary to creating a radio network using
   white space; in some regulatory domains, for some device types, it is
   a prerequisite to the use cases below.  The radio network is created
   by a master device.  Before the master device can transmit in white
   space spectrum, it must contact a trusted database where the device
   can learn if any channels are available for it to use.  Before the
   database will provide information on available radio channels, the
   master device must register with the trusted database.  Specific
   requirements for registration come from individual regulatory domains
   and may be different.

   Figure 2 shows an example deployment of this scenario.









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                              \|/                            ----------
                               |                             |Database|
                               |                     .---.   /---------
                             |-|---------|          (     ) /
     \|/                     |  Master   |         /       \
      |                   /  |           |========( Internet )
      |                  /   |-----------|         \        /
    +-|----+   (AirIF)                              (      )
    |Master|  /                                      (----)
    |      | /
    +------+

    Figure 2: Example illustration of registration requirement in white
                              space use-case

   A simplified operational scenario showing registration consists of
   the following steps:

   1.  The master device must register with its most current and up-to-
       date information.  Typically the master device will register
       prior to operating in white space for the first time after power
       up, after changing location by a predetermined distance, and
       after regular time intervals.

   2.  The master device shall provide to the database during
       registration all information required according to local
       regulatory requirements.  This information may include, but is
       not limited to, the Device ID, serial number assigned by the
       manufacturer the device's location, device antenna height above
       ground, name of the individual or business that owns the device,
       name of a contact person responsible for the device's operation
       address for the contact person, email address for the contact
       person and phone number of the contact person.

   3.  The database shall respond to the registration request with an
       acknowledgement code to indicate the success or failure of the
       registration request.  Additional information may be provided
       according to local regulator requirements.

4.2.  Use cases

4.2.1.  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



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   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.  Each master/AP has a
   connection to the Internet and may provide Internet connectivity to
   other master and slave devices.

   Figure 3 shows an example deployment of this scenario.



    --------
    |Device|\                \|/                             ----------
    |  1   | (TDD AirIF)\     |                              |Database|
    --------             \    |                     (----)   /---------
          |               \ |-|---------|          (      ) /
          |                \|  Master   |         /        \
    --------               /|           |========( Internet )
    |Device|  /(TDD AirIF)/ |-----------|         \        /
    |  2   | /             /                       (      )
    -------               /                         (----)
      o   |              /
      o   |   (TDD AirIF)
      o   |  /
    --------/
    |Device|
    |  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 to slave devices, including
   the ability to clear WSDs from select channels, is described.  This
   scenario 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).  A local
        regulator may identify exception cases where a master may
        initialize over white space (e.g. the FCC allows a master to
        initialize over TV white space in certain conditions).




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   2.   The master/AP has Internet connectivity, determines its location
        (either from location determination capability or from saved
        value that was set during installation), and establishes a
        connection to a trusted white space database (see
        Section 4.1.1).

   3.   The master/AP registers with the trusted database according to
        regulatory domain requirements (see Section 4.1.2).

   4.   Following the successful registration process (if registration
        is required), the master/AP will send a query to the trusted
        database requesting a list of available WS channels based upon
        its geolocation.  The complete set of parameters to be provided
        from the master to the database is specified by the local
        regulator.  Parameters may include WSD location, accuracy of
        that location, device antenna height, device identifier of a
        slave device requesting channel information.

   5.   If the master/AP has met all regulatory domain requirements
        (e.g. been previously authenticated, etc), 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,
        associated maximum power levels or a notification of any
        additional requirements for sensing.

   6.   Once the master/AP has met all regulatory domain requirements
        (e.g. authenticated the WS channel list response message from
        the database, etc), the AP selects one or more available WS
        channels from the list.  Prior to initiating transmission, if
        required by local regulation, the master/AP informs the database
        of the frequencies and power level it has chosen.  This
        reporting of the frequencies and power levels to the database is
        repeated for each slave device that associated with the master.

   7.   The slave or user device scans the TV bands to locate a
        master/AP transmission, and associates with the AP.

   8.   The slave/user device queries the master for a channel list.  In
        the query the slave/user device provides attributes that are
        defined by local regulations.  These may include the slaves'
        Device ID and its geolocation.

   9.   Once the master/AP has met all regulatory domain requirements
        (e.g. validating the Device ID with the trusted database, etc)
        the master provides the list of channels locally available to
        the slave/user device.  Prior to initiating transmission, if
        required by local regulation, the slave device informs the
        master/AP of the frequencies and power level it has chosen, and



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        the master/AP relays this information to the database.

   10.  The master sends an enabling signal to establish that the slave/
        user device is still within reception range of the master.  This
        signal shall be encoded to ensure that the signal originates
        from the master that provided the available list of channels.

   11.  Periodically, at an interval established by the local regulator,
        the slave/user device must receive an enabling signal from the
        master that provided the available list of channels or contact a
        master to re-verify or re-establish the list of available
        channels.

   12.  The master/AP must periodically repeat the process to request a
        channel list from the database, steps 4 through 6 above.  The
        frequency to repeat the process is determined by the local
        regulator.  If the response from the database indicates a
        channel being used by the master/AP is not available, the
        master/AP must stop transmitting on that channel immediately.
        In addition or optionally, the database may send a message to
        the master/AP to rescind the availability of one or more
        channels.  The master/AP must stop transmitting on that channel
        immediately.

   13.  The slave or user device must periodically repeat the process to
        request a channel list from the master/AP, steps 8 and 9 above.
        The frequency to repeat the process is determined by the local
        regulator.  If the response from the master/AP indicates that a
        channel being used by the slave or user device is not available,
        the slave or user device must stop transmitting on that channel
        immediately.  In addition or optionally, the database may send a
        message to the master/AP to rescind the availability of one or
        more channels.  The master/AP must then notify the slave or user
        device of the rescinded channels.  The slave or user device must
        stop transmitting on that channel immediately.

4.2.2.  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 of
   kilometers, up to 100 km), and a number of available radio channels.
   Some of the masters/BSs may be deployed and operated by a single
   entity, i.e., there can be centralized coordination between these



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   masters/BSs, whereas other masters/BSs may be deployed and operated
   by operators competing for the radio channels where decentralized
   coordination using the air-interface would be required.  The BS in
   this scenario uses a TDD radio technology and transmits at or below a
   transmit power (EIRP) limit established by the local regulator.  Each
   base station has a connection to the Internet and may provide
   Internet connectivity to multiple slaves/user devices.  End-user
   terminals or devices may be fixed or portable.

   Figure 4 shows an example deployment of this scenario.



      -------
      |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, determines its location
        (either from location determination capability or from a saved
        value that was set during installation), and establishes a
        connection to a trusted white space database (see
        Section 4.1.1).

   3.   The master/BS registers with the trusted database service (see
        Section 4.1.2).  Meanwhile the DB administrator may be required
        to store and forward the registration information to the



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        regulatory authority.  If a trusted white space database service
        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 successful registration process (if registration
        is required), the master/BS will send a query to the trusted
        database requesting a list of available WS channels based upon
        its geolocation.  The complete set of parameters to be provided
        from the master to the database is specified by the local
        regulator.  Parameters may include WSD identifier, location,
        accuracy of that location, device antenna height, etc...

   5.   If the master/BS has been previously authenticated, the database
        responds with a list of available white space channels that may
        be used by the master/BS and optionally a maximum transmit power
        (EIRP) for each channel, a duration of time the channel may be
        used or a notification of any additional requirement for
        sensing.

   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.  Such selection may be improved based
        on a set of queries to the DB involving a number of hypothetical
        slave or user devices located at various locations over the
        expected service area so that the final intersection of these
        resulting WS channel lists allows the selection of a channel
        that is likely available over the entire service area to avoid
        potential interference at the time of slave/user terminal
        association.  The operator may also disallow some channels from
        the list to suit local needs if required.

   7.   The slave or user device scans the TV bands to locate a WRAN
        transmission, and associates with the master/BS.

   8.   In some regulatory domains, before a master device sends a
        channel list, the slave/user device provides its geolocation to
        the BS which, in turn, queries the database for a list of
        channels available at the slave's geolocation.

   9.   Once this list of available channels is received from the
        database by the master, the latter will decide, based on this
        list of available channels and on the lists for all its other
        associated slaves/user devices whether it should: a) continue
        operation on its current channel if this channel is available to
        all slaves/user devices, b) continue operation on its current
        channel and not allow association with the new slave/user device
        in case this channel is not available at its location or c)



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        change channel to accommodate the new slave.  In the latter
        case, the master will notify all its associated slaves/user
        devices of the new channel to which they have to move.

   10.  The master/BS must periodically repeat the process to request a
        list of available channels from the database for itself and for
        all its associated slaves/user devices.  If the response from
        the database indicates that the channel being used by the
        master/BS is no longer available for its use, the master/BS must
        indicate the new operating channel to all its slave/user
        terminals, stop transmitting on the current channel and move to
        the new operating channel immediately.  If the channel that a
        slave/user terminal is currently using is no longer included in
        the list of locally available channels, the master may either
        drop its association with the slave/user device so that this
        device ceases all operation on its current channel or the master
        may decide to move the entire cell to another channel to
        accommodate the slave/user terminal and indicate the new
        operating channel to all its slave/user devices before dropping
        the link.  The slave/user devices may then move to the
        identified new operating channel or scan for another WRAN
        transmission on a different channel.  The frequency to repeat
        the process is determined by the local regulator.

   11.  The slave/user device must transmit its new geographic location
        every time it changes so that the repeated process described
        under item 10 can rely on the most up-to-date geolocation of the
        slave/user device.

4.2.3.  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



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   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.


                              \|/
                               |
                               |
                             |-|---------|
                             | Master/AP |\
                            /| Router    | \
                  Streaming/ |-----------|  \
       --------  /                           \               -----------
       |Slave/| /                             \      (----)  | Database |
       |WS Dev|                                \    (      ) /----------
        ------- \                               \  /        \
                 \                               X( Internet )
                  \                             /  \        /
                   Signaling  \|/              /    (      )\
                          \    |              /      (----)  \----------
                           \   |             /                | YouTube |
                            \|-|---------|  /                 ----------
                             |           | /
                             | 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 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.



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   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
       connection to stream the video.

4.2.4.  White space serving as backhaul

   In this use case Internet connectivity service is provided to users
   over a more common wireless standard such as Wi-Fi with white space
   entities providing backhaul connectivity to the Internet.  In a
   typical deployment scenario an end user has a device with a radio
   such as Wi-Fi.  An Internet service provider or a small business
   owner wants to provide Wi-Fi Internet connectivity service to their
   customers.  The location where Internet connectivity service via
   Wi-Fi is to be provided is within the coverage area of a white space
   master (e.g.  Hotspot or Wide-Area/Rural network).  The service
   provider installs a white space slave device and connects it to the
   Wi-Fi access point(s).  Wi-Fi access points with an integrated white
   space slave component may also be used.  This deployment scenario is
   typically characterized by a WS master/AP/BS providing local
   coverage.  The master/AP has a connection to the Internet and
   provides Internet connectivity to slave devices that are within its
   coverage area.  The WS slave device is 'bridged' to a Wi-Fi network
   thereby enabling Internet connectivity service to Wi-Fi devices.  The
   WS Master/AP/BS which has some form of Internet connectivity (wired
   or wireless) queries the database and obtains available channel
   information.  It then provides service using those channels to slave
   devices which are within its coverage area.

   Figure 6 shows an example deployment of this scenario.

















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                        \|/     white    \|/    \|/   Wi-Fi \|/
                         |      space     |      |           |
                         |                |      |         |-|----|
       |--------|      |-|---------|    |-|------|-|       | Wi-Fi|
       |        |      | Master    |    |  Slave   |       | Dev  |
       |Internet|------| (AP/BS)   |    |  Bridge  |       |------|
       |        |      |           |    | to Wi-Fi |
       |--------|      |-----------|    |----------|        \|/
                                                             |
                                                           |-|----|
                                                           | Wi-Fi|
                                                           | Dev  |
                                                           |------|

                         Figure 6: WS for backhaul

   Once the bridged device (WS + Wi-Fi) is connected to a master and WS
   network, a simplified operation scenario of backhaul for Wi-Fi
   consists of the following steps:

   1.  A bridged device (WS + Wi-Fi) is connected to a master device
       operating in the WS spectrum.  The bridged device operates as a
       slave device in either Hotspot or Wide-Area/Rural Internet use
       cases described above.

   2.  Once the slave device is connected to the master, the Wi-Fi
       access point has Internet connectivity as well.

   3.  End users attach to the Wi-Fi network via their Wi-Fi enabled
       devices and receive Internet connectivity.

4.2.5.  Rapid deployed network for emergency scenario

   Organizations involved in handling emergency operations often have a
   fully owned and controlled infrastructure, with dedicated spectrum,
   for day to day operation.  However, lessons learned from recent
   disasters show such infrastructures are often highly affected by the
   disaster itself.  To set up a replacement quickly, there is a need
   for fast reallocation of spectrum, where in certain cases spectrum
   can be cleared for disaster relief.  To utilize unused or cleared
   spectrum quickly and reliably, automation of allocation, assignment
   and configuration is needed.  A preferred option is to make use of a
   robust protocol, already adopted by radio manufacturers.  This
   approach does in no way imply such organizations for disaster relief
   must compete on spectrum allocation with other white spaces users,
   but they can.  A typical network topology would include wireless
   access links to the public Internet or private network, wireless ad
   hoc network radios working independent of a fixed infrastructure and



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   satellite links for backup where lack of coverage, overload or outage
   of wireless access links occur.

   Figure 7 shows an example deployment of this scenario.

                              \|/
                               | ad hoc
                               |
                             |-|-------------|
                             | Master node   |       |------------|
     \|/                     | with          |       | Whitespace |
      | ad hoc              /| backhaul link |       | Database   |
      |             /------/ |---------------|       |------------|
   ---|------------/                |      \           /
   | Master node   |                |       |      (--/--)
   | without       |                |       ------(       )
   | backhaul link |                |  Wireless  / Private \
   ----------------\                |    Access (   net or  )
                    \                |            \ Internet )
                     \    \|/        |      -------(        /\
                      \    | ad hoc  |      |       (------)  \---------
                       \   |         |      /                 | Other  |
                        \--|-------------  /Satellite         | nodes  |
                        | Master node   | / Link              ----------
                        | with          |/
                        | backhaul link |
                        -----------------


       Figure 7: Rapid deployed network with partly connected nodes

   In the ad hoc network, all nodes are master nodes in a way that they
   allocate RF channels from the white space database.  However, the
   backhaul link may not be available to all nodes, such as depicted for
   the left node in Figure 7.  To handle RF channel allocation for such
   nodes, a master node with a backhaul link relays or proxies the
   database query for them.  So master nodes without a backhaul link
   follow the procedure as defined for clients.  The ad hoc network
   radios utilize the provided RF channels.  Details on forming and
   maintenance of the ad hoc network, including repair of segmented
   networks caused by segments operating on different RF channels, is
   out of scope of spectrum allocation.

4.2.6.  Mobility

   In this use case, the user has a non-fixed (portable or mobile)
   device and is riding in a vehicle.  The user wants to have
   connectivity to another device which is also moving.  Typical



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   deployment scenarios include urban areas and rural areas where the
   user may connect to other users while moving.  This deployment
   scenario is typically characterized by a master device with low
   antenna height, Internet connectivity by some connection that does
   not utilize TV white space, and some means to predict its path of
   mobility.  This knowledge of mobility could be simple (GPS plus
   accelerometer), sophisticated (GPS plus routing and mapping function)
   or completely specified by the user via user-interface.

   Figure 8 shows an example deployment of this scenario.

                 \|/                            \|/
                  |                              |
                  |                              |
                +-|---------+                  +-|---------+
                |   TVWS    |                  |   TVWS    |
                |Master Dev |                  |Master Dev |
                +-----------+                  +-----------+
                             \     (----)     /        \
                              \   (      )   /          \    \|/
                               \ /        \ /      WS AirIF   |
                                ( Internet )              \   |
                                 \        /                \+-|--------+
                                  (      )\----------+      |   TVWS   |
                                   (----) | Database |      |Slave Dev |
                                          +----------+      +----------+


   Figure 8: Example illustration of mobility in TV white space use-case

   A simplified operational scenario utilizing TV whitespace to provide
   connectivity service in a mobility environment consists of the
   following steps:

   1.   The mobile master device powers up with its WS radio in idle or
        listen mode only (no active transmission on the WS frequency
        band).

   2.   The mobile master has Internet connectivity, determines its
        location, and establishes a connection to a trusted white space
        database (see Section 4.1.1).

   3.   The mobile master registers with the trusted database according
        to regulatory domain requirements (see Section 4.1.2).

   4.   Following the successful registration process (if registration
        is required), the mobile master will send a query to the trusted
        database requesting a list of available WS channels based upon



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        its current location, other parameters required by the local
        regulator (see Section 4.2.1, step 4) and a prediction of its
        future location.  The current location is specified in latitude
        and longitude.  The method to specify the future location is
        TBD, potential methods include movement vector (direction and
        velocity), a set of latitude/longitude points which specify a
        closed polygon where the future location is within the polygon,
        or similar.

   5.   If the mobile master has met all regulatory domain requirements
        (e.g. been previously authenticated, etc), the database responds
        with a list of available white space channels that the mobile
        master may use, and optional information which may include (1) a
        duration of time for the use of each channel (2) a maximum
        transmit power for each channel and (3) notification of any
        additional requirement for sensing.

   6.   Once the mobile master has met all regulatory domain
        requirements (e.g. authenticated the WS channel list response
        message from the database, etc), the master selects one or more
        available WS channel(s) from the list for use.  At this point
        the mobile master may begin direct communication with another
        mobile master using methods outside the scope of PAWS.

   7.   The slave/user device scans to locate a mobile master
        transmission, and associates with the mobile master.

   8.   The slave/user device queries the master for a channel list,
        providing to the master the slave's device identification, and
        optionally its geolocation and a prediction of its future
        location.

   9.   Once the mobile master has met all regulatory domain
        requirements (e.g. the slave's device identification is verified
        by the database), the mobile master provides the list of
        channels locally available to the slave/user device.

   10.  If the mobile master moves outside the predicted range of future
        positions in step 4, it must repeat the process to request a
        channel list from the database, steps 4 through 6 above.  If the
        response from the database indicates a channel being used by the
        mobile master is not available, the master/AP must stop
        transmitting on that channel immediately.

   11.  The slave or user device must periodically repeat the process to
        request a channel list from the master/AP, steps 8 and 9 above.
        The frequency to repeat the process is determined by the local
        regulator.  If the response from the master/AP indicates that a



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        channel being used by the slave or user device is not available,
        the slave or user device must stop transmitting on that channel
        immediately.  In addition or optionally, the database may send a
        message to the master/AP to rescind the availability of one or
        more channels.  The master/AP must then notify the slave or user
        device of the rescinded channels.  The slave or user device must
        stop transmitting on that channel immediately.

4.2.7.  Indoor Networking

   In this use case, the users are inside a house or office.  The users
   want to have connectivity to the Internet or to equipment in the same
   or other houses / offices.  This deployment scenario is typically
   characterized by master devices within buildings, that are connected
   to the Internet using a method that does not utilize whitespace.  The
   master devices can establish whitespace links between themselves, or
   between themselves and one or more user devices.

   Figure 9 shows an example deployment of this scenario.

                             \|/
                              |
      +-------+               |
      |TVWS   |\            +-|---------+
      |Usr Dev|  WS AirIF \ |   TVWS    |\
      +-------+            X|Master Dev | \
                          / +-----------+  \
      +-------+  WS AirIF          |        \               +----------+
      |TVWS   |/                   |         \      (----)  | Database |
      |Usr Dev|                    |          \    (      ) /----------+
      +-------+                WS AirIF        \  /        \
                                   |            X( Internet )
                                   |           /  \        /
      +-------+              \|/   |          /    (      )
      |TVWS   |\              |    |         /      (----)
      |Usr Dev|  WS AirIF     |    |        /
      +-------+          \  +-|---------+  /
                          \ |   TVWS    | /
                            |Master Dev |/
                            +-----------+


     Figure 9: Example illustration of indoor TV white space use-case

   A simplified operational scenario utilizing TV whitespace to provide
   indoor networking consists of the following steps:





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   1.  The master device powers up with its whitespace radio in idle or
       listen mode only (no active transmission on the whitespace
       frequency band).

   2.  The master device has Internet connectivity, determines its
       location (either from location determination capability or from a
       saved value that was set during installation), and establishes a
       connection to a trusted white space database (see Section 4.1.1).

   3.  The master device registers with the trusted database according
       to regulatory domain requirements (see Section 4.1.2).

   4.  Following the successful registration process (if registration is
       required), the master device sends a query to the trusted
       database requesting a list of available WS channels based upon
       its geolocation.  The complete set of parameters to be provided
       from the master to the database is specified by the local
       regulator.  Parameters may include WSD location, accuracy of that
       location, device antenna height, device identifier of a slave
       device requesting channel information.

   5.  If the master has met all regulatory requirements, the database
       responds with a list of available white space channels that the
       master device may use, and optional information which may include
       inter alia (1) a duration of time for the use of each channel
       (channel validity time) (2) a maximum radiated power for each
       channel, and (3) directivity and other antenna information.

   6.  Once the master device authenticates the whitespace channel list
       response message from the database, the master device selects one
       or more available whitespace channels from the list.  At this
       point the mobile master may begin direct communication with
       another mobile master using methods outside the scope of PAWS.

   7.  The user device(s) scan(s) the white space bands to locate the
       master device transmissions, and associates with the master.

4.2.8.  Machine to Machine (M2M)

   In this use case, each "machine" includes a white space slave device
   and can be located anywhere, fixed or on the move.  Each machine
   needs to have connectivity to the Internet and or to other machines
   in the vicinity.  Machine communication over a TVWS channel, whether
   to a master device or to another machine (slave device), is under the
   control of a master device.  This deployment scenario is typically
   characterized by a master device with Internet connectivity by some
   connection that does not utilize TV white space.




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   Figure 10 shows an example deployment of this scenario.

                             \|/
                              |
                              |
                            +-|---------+
                            |   TVWS    |\
                           /|Master Dev | \
                          / +-----------+  \
                 WS AirIF                   \               +----------+
      +-------+ /                            \      (----)  | Database |
      |Machine|                               \    (      ) /----------+
      +-------+                                \  /        \
          |                                     X( Internet )
       WS AirIF                                   \        /
          |                                        (      )
      +-------+                                     (----)
      |Machine|
      +-------+ \           +-------+
                 WS AirIF-- |Machine|
                            +-------+

      Figure 10: Example illustration of M2M TV white space use-case

   A simplified operational scenario utilizing TV whitespace to provide
   machine to machine connectivity consists of the following steps:

   1.  The master device powers up with its whitespace radio in idle or
       listen mode only (no active transmission on the whitespace
       frequency band).

   2.  The master device has Internet connectivity, determines its
       location (either from location determination capability or from
       saved value that was set during installation), and establishes a
       connection to a trusted white space database (see Section 4.1.1).

   3.  The master/AP registers with the trusted database according to
       regulatory domain requirements (see Section 4.1.2).

   4.  Following successful registration (if registration is required),
       the master device sends its geolocation and location uncertainty
       information, and optionally additional information which may
       include (1) device ID and (2) antenna characteristics, to a
       trusted database, requesting a list of available whitespace
       channels based upon this information.

   5.  If the master has met all regulatory domain requirements, the
       database responds with a list of available white space channels



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       that the master device may use, and optional information which
       may include inter alia (1) a duration of time for the use of each
       channel (channel validity time) (2) a maximum radiated power for
       each channel or a notification of any additional requirements for
       sensing.

   6.  Once the master device authenticates the whitespace channel list
       response message from the database, the master device selects one
       or more available whitespace channels from the list.

   7.  The slave devices fitted to the machines scan the TV bands to
       locate the master transmissions, and associate with the master
       device.

   8.  Further signaling can take place outside scope of PAWS to
       establish direct links among those slave devices that have
       associated with the same master device.  At all times these
       direct links are under the control of the master device.  For
       example, common to all use cases, there may be a regulatory
       requirement for transmissions from slave to master to cease
       immediately if so requested by the master, or if connection to
       the master is lost for more than a specified period of time.
       When one of these conditions occurs, transmissions from slave to
       slave would also cease.  Various mechanisms could be used to
       detect loss of signal from the master, for example by requiring
       masters to transmit regular beacons if they allow slave to slave
       communications.  Direct slave to slave transmissions could only
       restart if each slave subsequently restores its connection to the
       same master, or each slave joins the network of another master.


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 Figure 11:







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           -----------
           |  Master |
           |WS Device|                              ------------
           |Lat: X   |\           .---.    /--------|Database X|
           |Long: Y  | \         (     )  /         ------------
           -----------  \-------/       \/               o
                              ( Internet )               o
           -----------  /------(        )\               o
           |  Master | /        (       ) \
           |WS Device|/          (_____)   \         ------------
           |Lat: X   |                      \--------|Database Y|
           |Long: Y  |                               ------------
           -----------


    Figure 11: High level view of the White space database architecture

   In Figure 11, 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 its 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



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   operating in available spectrum.  Information about available
   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 IEEE
       802.11af, IEEE 802.15.4m, IEEE 802.16, IEEE 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 its 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 is likely to 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.


6.  Requirements

6.1.  Normative Requirements

      D. Data Model Requirements:

      D.1:  The Data Model MUST support specifying the location of the
            WSD, the uncertainty in meters, the height & its
            uncertainty, and confidence in percentage of the location
            determination.  The Data Model MUST support both North
            American Datum of 1983 and WGS84.

      D.2:  The Data Model MUST support specifying the regulatory domain
            and its corresponding data requirements.

      D.3:  The Data Model MUST support specifying an ID of the
            transmitter device.  This ID would contain the ID of the
            transmitter device that has been certified by a regulatory
            body for its regulatory domain.  The Data Model MUST support
            a device class.  The Data Model MUST support specifying
            information about the type of RAT of the transmitter device.







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      D.4:  The Data Model MUST support specifying a manufacturer's
            serial number for a white space device.

      D.5:  The Data Model MUST support specifying the antenna and
            radiation related parameters of the subject, such as:

               antenna height

               antenna gain

               maximum output power, EIRP (dBm)

               antenna radiation pattern (directional dependence of the
               strength of the radio signal from the antenna)

               spectrum mask with lowest and highest possible frequency

               spectrum mask in dBr from peak transmit power in EIRP,
               with specific power limit at any frequency linearly
               interpolated between adjacent points of the spectrum mask

               measurement resolution bandwidth for EIRP measurements

      D.6:  The Data Model MUST support specifying owner and operator
            contact information for a transmitter.  This includes the
            name of the transmitter owner, name of transmitter operator,
            postal address, email address and phone number of the
            transmitter operator.

      D.7:  The Data Model MUST support specifying a list of available
            channels.  The Data Model MUST support specification of this
            information by channel numbers and by start and stop
            frequencies.  The Data Model MUST support a channel
            availability schedule and maximum power level for each
            channel in the list.

      D.8:  The Data Model MUST support specifying channel availability
            information for a single location and an area (e.g. a
            polygon defined by multiple location points or a geometric
            shape such as a circle).

      D.9:  The Data Model MUST support specifying the frequencies and
            power levels selected for use by a device in the
            acknowledgement message.

      P. Protocol Requirements:





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      P.1:   The protocol MUST provide a mechanism to enable WSD
             discovery.  In some environments, a listing of the approved
             white space databases is maintained by the national
             regulator.  The protocol MUST support discovery of a
             database using a listing approved by a national regulator.

      P.2:   The address of a database (e.g. in form of a URI) can be
             preconfigured in a master device.  The master device MUST
             be able to contact a database using a pre-configured
             database address.

      P.3:   The protocol MUST support determination of regulatory
             domain governing its current location.

      P.4:   The protocol MUST provide the ability for the database to
             authenticate the master device.

      P.5:   The protocol MUST provide the ability for the master device
             to verify the authenticity of the database with which it is
             interacting.

      P.6:   The messages sent by the master device to the database and
             the messages sent by the database to the master device MUST
             support integrity protection.

      P.7:   The protocol MUST provide the capability for messages sent
             by the master device and database to be encrypted.

      P.8:   The protocol MUST support the master device registering
             with the database.

      P.9:   The protocol MUST support a registration acknowledgement
             including appropriate result codes.

      P.10:  The protocol MUST support a channel query request from the
             master device to the database.  The channel query request
             message MUST include parameters as required by local
             regulatory requirement.  These parameters MAY include any
             of the parameters and attributes required to be supported
             in the Data Model Requirements.

      P.11:  The protocol MUST support a channel query response from the
             database to the master device.  The channel query response
             message MUST include parameters as required by local
             regulatory requirement.  These parameters MAY include any
             of the parameters and attributes required to be supported
             in the Data Model Requirements.




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      P.12:  The protocol MUST support a channel usage message from the
             master device to the database.  The channel usage message
             MUST include parameters as required by local regulatory
             requirement for the master and its associated slaves.
             These parameters MAY include any of the parameters and
             attributes required to be supported in the Data Model
             Requirements.

      P.13:  The protocol MUST support a channel usage message
             acknowledgement.

      P.14:  The protocol MUST support a validation request from the
             master to the database to validate a slave device.  The
             validation request MUST include the slave device ID.

      P.15:  The protocol MUST support a validation response from the
             database to the master to indicate if the slave device is
             validated by the WSDB.  The validation response MUST
             include a response code.

      P.16:  The protocol between the master device and the database
             MUST support the capability to change channel availability
             information on short notice.

      P.17:  The protocol between the master device and the database
             MUST support a channel availability request which specifies
             a geographic location as an area as well as a point.

6.2.  Non-normative requirements

   O. Operational Requirements:

   O.1:   The database and the master device MUST be connected to the
          Internet.

   O.2:   A master device MUST be able to determine its location
          including uncertainty and confidence level.  A fixed master
          device MAY use a location programmed at installation or have
          the capability to determine its location to the required
          accuracy.  A mobile master device MUST have the capability to
          determine its location to the required accuracy.

   O.3:   The master device MUST identify a database to which it will
          register, make channel requests, etc...  The master device MAY
          select a database for service by discovery at runtime or the
          master device MAY select a database for service by means of a
          pre-programmed URI address.




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   O.4:   The master device MUST implement at least one connection
          method to access the database.  The master device MAY contact
          a database directly for service (e.g. as defined by FCC) or
          the master device MAY contact a listing server first followed
          by contact to a database (e.g. as defined by Ofcom).

   O.5:   The master device MUST obtain an indication about the
          regulatory domain governing operation at its current location,
          i.e. the master device MUST know if it operates under
          regulations from FCC, Ofcom, etc...

   O.6:   The master device MAY register with the database according to
          local regulatory policy.  Not all master devices will be
          required to register.  Specific events will initiate
          registration, these events are determined by regulator policy
          (e.g. at power up, after movement, etc...).  When local
          regulatory policy requires registration, the master device
          MUST register with its most current and up-to-date
          information, and MUST include all variables mandated by local
          regulator policy.

   O.7:   A master device MUST query the database for the available
          channels based on its current location before starting radio
          transmission in white space.  Parameters provided to the
          database MAY include device location, accuracy of the
          location, antenna characteristic information, device
          identifier of any slave device requesting channel information,
          etc...

   O.8:   The database MUST respond to an available channel list request
          from an authenticated and authorized device and MAY also
          provide time constraints, maximum output power, start and stop
          frequencies for each channel in the list and any additional
          requirements for sensing.

   O.9:   According to local regulator policy, a master device MAY
          inform the database of the actual frequency usage of the
          master and its slaves.  The master MUST include parameters
          required by local regulatory policy, e.g. device ID,
          manufacturer's serial number, channel usage and power level
          information of the master and its slaves.

   O.10:  After connecting to a master device's radio network a slave
          device MUST query the master device for a list of available
          channels.  The slave MUST include parameters required by local
          regulatory policy, e.g. device ID, device location.





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   O.11:  According to local regulatory policy, the master device MAY
          query the database with parameters received from the slave
          device.

   O.12:  The database MUST respond to a query from the master device
          containing parameters from a slave device.

   O.13:  A master device MUST repeat the query to the database for the
          available channels as often as required by the regulation
          (e.g., FCC requires once per day) to verify that the operating
          channels continue to remain available.

   O.14:  A master device which changes its location more than a
          threshold distance (specified by local regulatory policy)
          during its operation, MUST query the database for available
          operating channels each time it moves more than the threshold
          distance (e.g., FCC specifies 100m) from the location it
          previously made the query.

   O.15:  According to local regulator policy, a master device may
          contact a database via proxy service of another master device.

   O.16:  A master device MUST be able to query the whitespace database
          for channel availability information for a specific expected
          coverage area around its current location.

   O.17:  A Master device MUST include its unique identity in all
          message exchanges with the database.

6.3.  Guidelines

   The current scope of the working group is limited and is reflected in
   the requirements captured in Section 6.1.  However white space
   technology itself is expected to evolve and address other aspects
   such as co-existence and interference avoidance, spectrum brokering,
   alternative spectrum bands, etc.  The design of the data model and
   protocol should be cognizant of the evolving nature of white space
   technology and consider the following set of guidelines in the
   development of the data model and protocol:

   1.  The data model SHOULD provide a modular design separating out
       messaging specific, administrative specific, and spectrum
       specific parts into separate modules.

   2.  The protocol SHOULD support determination of which administrative
       specific and spectrum specific modules are used.





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7.  IANA Considerations

   This document has no requests to IANA.


8.  Security Considerations

   Threat model for the PAWS protocol

   Assumptions:

   It is assumed that an attacker has full access to the network medium
   between the master device and the white space database.  The attacker
   may be able to eavesdrop on any communications between these
   entities.  The link between the master device and the white space
   database can be wired or wireless and provides IP connectivity.

   It is assumed that both the master device and the white space
   database have NOT been compromised from a security standpoint.

   Threat 1: User modifies a device to masquerade as another valid
   certified device

      Regulatory environments require that devices be certified and
      register in ways that accurately reflect their certification.
      Without suitable protection mechanisms, devices could simply
      listen to registration exchanges, and later registering claiming
      to be those other devices.  Such replays would allow false
      registration, violating regulatory regimes.  A white space
      database may be operated by a commercial entity which restricts
      access only to authorized users.  A master device MAY need to
      identify itself to the database and be authorized to obtain
      information about available channels.

   Threat 2: Spoofed white space database

      A master device discovers a white space database(s) through which
      it can query for channel information.  The master device needs to
      ensure that the white space database with which it communicates
      with is an authentic entity.  The white space database needs to
      provide its identity to the master device which can confirm the
      validity/authenticity of the database.  An attacker may attempt to
      spoof a white space database and provide responses to a master
      device which are malicious and result in the master device causing
      interference to the primary user of the spectrum.






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   Threat 3: Modifying a query request

      An attacker may modify the query request sent by a master device
      to a white space database.  The attacker may change the location
      of the device or the capabilities in terms of its transmit power
      or antenna height etc. which could result in the database
      responding with incorrect information about available channels or
      max transmit power allowed.  The result of such an attack is that
      the master device would cause interference to the primary user of
      the spectrum.  It could also result in a denial of service to the
      master device by indicating that no channels are available.

   Threat 4: Modifying a query response

      An attacker could modify the query response sent by the white
      space database to a master device.  The channel information or
      transmit power allowed type of parameters carried in the response
      could be modified by the attacker resulting in the master device
      using channels that are not available at a location or
      transmitting at a greater power level than allowed resulting in
      interference to the primary user of that spectrum.  Alternatively
      the attacker may indicate no channel availability at a location
      resulting in a denial of service to the master device.

   Threat 5: Unauthorized use of channels by an uncertified device

      An attacker may be a master device which is not certified for use
      by the relevant regulatory body.  The attacker may listen to the
      communication between a valid master device and white space
      database and utilize the information about available channels in
      the response message by utilizing those channels.  The result of
      such an attack is unauthorized use of channels by a master device
      which is not certified to operate.  The master device querying the
      white space database may be operated by a law-enforcement agency
      and the communications between the device and the database are
      intended to be kept private.  A malicious device should not be
      able to eavesdrop on such communications.

   Threat 6: Third party tracking of white space device location and
   identity

      A white space database in a regulatory domain may require a master
      device to provide its identity in addition to its location in the
      query request.  Such location/identity information can be gleaned
      by an eavesdropper and used for tracking purposes.  A master
      device may prefer to keep the location/identity information hidden
      from eavesdroppers, hence the protocol should provide a means to
      protect the location and identity information of the master device



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      and prevent tracking of locations associated with a white space
      database query.  When the master device sends both its identity
      and location to the DB, the DB is able to track it.  If a
      regulatory domain does not require the master device to provide
      its identity to the white space database, the master device may
      decide not to send its identity, to prevent being tracked by the
      DB.

   Threat 7: Malicious individual acts as a PAWS entity (spoofing DB or
   as MiM) to terminate or unfairly limit spectrum access of devices for
   reasons other than incumbent protection

      A white space database MAY include a mechanism by which service
      and channels allocated to a master device can be revoked by
      sending an unsolicited message.  A malicious node can pretend to
      be the white space database with which a master device has
      registered or obtained channel information from and send a revoke
      message to that device.  This results in denial of service to the
      master device.

   Threat 8: Natural disaster resulting in inability to obtain
   authorization for white space spectrum use by emergency responders

      In the case of a sizable natural disaster a lot of Internet
      infrastructure ceases to function.  Emergency services users need
      to reconstitute quickly and will rely on establishing radio WANs.
      The potential for lot of radio WAN gear that has been unused
      suddenly needs to be pressed into action.  And the radio WANs need
      frequency authorizations to function.  Regulatory entities may
      also authorize usage of additional spectrum in the affected areas.
      The white space radio entities may need to establish communication
      with a database and obtain authorizations.  In cases where
      communication with the white space database fails, the white space
      devices cannot utilize white space spectrum.  Emergency services,
      which require more spectrum precisely at locations where network
      infrastructure is malfunctioning or overloaded, backup
      communication channels and distributed white space databases are
      needed to overcome such circumstances.  Alternatively there may be
      other mechanisms which allow the use of spectrum by emergency
      service equipment without strict authorization or with liberal
      interpretation of the regulatory policy for white space usage.

   The security requirements arising from the above threats are captured
   in the requirements of section 6.1.







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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
   efficient usage of spectrum via means such as sensing or by querying
   a database to determine available spectrum at a given location for
   opportunistic 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 examples
   of 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.  Acknowledgements

   The authors acknowledge Gabor Bajko, Teco Boot, Nancy Bravin, Rex
   Buddenberg, Gerald Chouinard, Stephen Farrell, Michael Fitch, Joel M.
   Halpern, Jussi Kahtava, Paul Lambert, Brian Rosen, Andy Sago, Peter
   Stanforth, John Stine and, Juan Carlos Zuniga for their contributions
   to this document.


11.  References

11.1.  Normative References

   [802.11p]  IEEE, "IEEE Standard for Information technology -
              Telecommunications and information exchange between
              systems - Local and metropolitan area networks - Specific
              requirements; Part 11: Wireless LAN Medium Access Control
              (MAC) and Physical Layer (PHY) Specifications; Amendment
              6: Wireless Access in Vehicular Environments; http://
              standards.ieee.org/getieee802/download/802.11p-2010.pdf",
              July 2010.

   [802.22]   IEEE, "IEEE Standard for Information technology -
              Telecommunications and information exchange between
              systems - Wireless Regional Area Networks (WRAN) -
              Specific requirements; Part 22: Cognitive Wireless RAN



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              Medium Access Control (MAC) and Physical Layer (PHY)
              Specifications: Policies and Procedures for Operation in
              the TV bands", July 2011.

   [FCC47CFR90.210]
              FCC, "Title 47 Telecommunication CFR Chapter I - Federal
              Communication Commission Part 90 - Private Land Mobile
              Radio Services - Section 210 Emission masks; http://
              edocket.access.gpo.gov/cfr_2010/octqtr/pdf/
              47cfr90.210.pdf", October 2010.

   [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.

11.2.  Informative References

   [3MOO]     FCC, "Federal Communications Commission, Third Memorandum
              Opinion and Order", April 2012.

   [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]
              FCC, "Federal Communications Commission, "Unlicensed
              Operation in the TV Broadcast Bands;
              http://edocket.access.gpo.gov/2010/pdf/2010-30184.pdf"",
              December 2010.

   [Ofcom Implementing]



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Internet-Draft    PAWS: Problem, uses and requirements         July 2012


              Ofcom, "Ofcom, "Implementing Geolocation; http://
              stakeholders.ofcom.org.uk/consultations/geolocation/
              statement/"", September 2011.

   [Ofcom Requirements]
              Ofcom, "Ofcom, Draft final regulatory requirements for
              white space devices in the UHF TV band", June 2012.

   [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


   Basavaraj Patil
   Nokia
   6021 Connection drive
   Irving, TX  75039
   USA

   Email: basavaraj.patil@nokia.com





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