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rfc:rfc6953

Internet Engineering Task Force (IETF) A. Mancuso, Ed. Request for Comments: 6953 Google Category: Informational S. Probasco ISSN: 2070-1721

                                                              B. Patil
                                                         Cisco Systems
                                                              May 2013
          Protocol to Access White-Space (PAWS) Databases:
                     Use Cases and Requirements

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.  This document
 includes the problem statement for the development of a protocol to
 access a database of white-space information followed by use cases
 and requirements for that protocol.  Finally, requirements associated
 with the protocol are presented.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Not all documents
 approved by the IESG are a candidate for any level of Internet
 Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6953.

Mancuso, et al. Informational [Page 1] RFC 6953 PAWS Use Cases and Requirements May 2013

Copyright Notice

 Copyright (c) 2013 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1.  Introduction to White Space  . . . . . . . . . . . . . . .  3
   1.2.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2.1.  In Scope . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2.2.  Out of Scope . . . . . . . . . . . . . . . . . . . . .  4
 2.  Conventions Used in This Document  . . . . . . . . . . . . . .  5
   2.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
   2.2.  Requirements Language  . . . . . . . . . . . . . . . . . .  5
 3.  Problem Statement  . . . . . . . . . . . . . . . . . . . . . .  6
   3.1.  Global Applicability . . . . . . . . . . . . . . . . . . .  6
   3.2.  Database Discovery . . . . . . . . . . . . . . . . . . . .  8
   3.3.  Device Registration  . . . . . . . . . . . . . . . . . . .  8
   3.4.  Protocol . . . . . . . . . . . . . . . . . . . . . . . . .  9
   3.5.  Data Model Definition  . . . . . . . . . . . . . . . . . .  9
 4.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   4.1.  Master-Slave White-Space Networks  . . . . . . . . . . . .  9
   4.2.  Offloading: Moving Traffic to a White-Space Network  . . . 11
   4.3.  White Space Serving as Backhaul  . . . . . . . . . . . . . 13
   4.4.  Rapid Network Deployment during Emergencies  . . . . . . . 14
   4.5.  White Space Used for Local TV Broadcaster  . . . . . . . . 15
 5.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 16
   5.1.  Data Model Requirements  . . . . . . . . . . . . . . . . . 16
   5.2.  Protocol Requirements  . . . . . . . . . . . . . . . . . . 17
   5.3.  Operational Requirements . . . . . . . . . . . . . . . . . 19
   5.4.  Guidelines . . . . . . . . . . . . . . . . . . . . . . . . 19
 6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
 7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 22
 8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
   8.1.  Normative References . . . . . . . . . . . . . . . . . . . 22
   8.2.  Informative References . . . . . . . . . . . . . . . . . . 22

Mancuso, et al. Informational [Page 2] RFC 6953 PAWS Use Cases and Requirements May 2013

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 (primary) user but are
 unused or unoccupied at specific locations and times are defined as
 "white space".  The concept of allowing additional (secondary)
 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 secondary transmissions do not
 interfere with the assigned use of the spectrum.  One interesting
 observation is that often, in a given physical location, the primary
 user(s) may not be using the entire band assigned to them.  The
 available spectrum for secondary transmissions would then depend on
 the location of the secondary user.  The fundamental issue is how to
 determine, for a specific location and specific time, if any of the
 assigned spectrum is available for secondary use.
 Academia and industry have studied multiple cognitive radio [CRADIO]
 mechanisms for use in such a scenario.  One simple mechanism is to
 use a geospatial database that contains the spatial and temporal
 profile of all primary licensees' spectrum usage, and require
 secondary users to query the database for available spectrum that
 they can use at their location.  Such databases can be accessible and
 queryable by secondary users on the Internet.
 Any entity that is assigned spectrum that is not densely used may be
 asked by a governmental regulatory agency to share it to allow for
 more intensive use of the spectrum.  Providing a mechanism by which
 secondary users share the spectrum with the primary user is
 attractive in many bands, in many countries.
 This document includes the problem statement followed by use cases
 and requirements associated with the use of white-space spectrum by
 secondary users via a database query protocol.  The final sections
 include the requirements associated with such a protocol.  Note that
 the IETF has undertaken to develop a database query protocol (see
 [PAWS]).

Mancuso, et al. Informational [Page 3] RFC 6953 PAWS Use Cases and Requirements May 2013

1.2. Scope

1.2.1. In Scope

 This document covers the requirements for a protocol to allow a
 device to access a database to obtain spectrum availability
 information.  Such a protocol should allow a device to perform the
 following actions:
 1.  Determine the relevant database to query.
 2.  Connect to and optionally register with the database using a
     well-defined protocol.
 3.  Provide geolocation and perhaps other data to the database using
     a well-defined format for querying the database.
 4.  Receive in response to the query a list of available white-space
     frequencies at the specified geolocation using a well-defined
     format for the information.
 5.  Send an acknowledgment to the database with information
     containing channels selected for use by the device and other
     device operation parameters.
 Note: The above protocol actions should explicitly or implicitly
 support the ability of devices to re-register and/or re-query the
 database when they change their locations or operating parameters.
 This will allow them to receive permission to operate in their new
 locations and/or with their new operating parameters, and to send
 acknowledgments to the database that include information on their new
 operating parameters.

1.2.2. Out of Scope

 The following topics are out of scope for this specification:
 1.  It is the device's responsibility to query the database for new
     spectrum when the device moves, changes operating parameters,
     loses connectivity, etc.  Other synchronization mechanisms are
     out of scope.
 2.  A rogue device may operate without contacting the database to
     obtain available spectrum.  Hence, enforcement of spectrum usage
     by devices is out of scope.

Mancuso, et al. Informational [Page 4] RFC 6953 PAWS Use Cases and Requirements May 2013

 3.  The protocol defines communications between the database and
     devices.  The protocol for communications between devices is out
     of scope.
 4.  Coexistence and interference avoidance of white-space devices
     within the same spectrum are out of scope.
 5.  Provisioning (releasing new spectrum for white-space use) is out
     of scope.

2. Conventions Used in This Document

2.1. Terminology

 Database:  A database is an entity that contains current information
    about available spectrum at a given location and time, as well as
    other types of information related to spectrum availability and
    usage.
 Device Class:  Identifies classes of devices including fixed, mobile,
    portable, etc.  May also indicate if the device is indoor or
    outdoor.
 Device ID:  An identifier for a device.
 Master Device:  A device that queries the database, on its own behalf
    and/or on behalf of a slave device, to obtain available spectrum
    information.
 Slave Device:  A device that queries the database through a master
    device.
 Trusted Database:  A database that is trusted by a device or provides
    data objects that are trusted by a device.
 White Space (WS):  Radio spectrum that is available for secondary use
    at a specific location and time.
 White-Space Device (WSD):  A device that uses white-space spectrum as
    a secondary user.  A white-space device can be a fixed or portable
    device such as an access point, base station, or cell phone.

2.2. Requirements Language

 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].

Mancuso, et al. Informational [Page 5] RFC 6953 PAWS Use Cases and Requirements May 2013

3. 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.  While databases are expected to support the
 rule set(s) of one or more regulatory domains, and the regulations
 and available spectrum associated with each rule set may vary, the
 fundamental operation of the protocol must be independent of any
 particular regulatory environment.
 An example of the high-level architecture of the devices and
 databases is shown in Figure 1.
  1. ———-

| Master |

               |WS Device|                              ------------
               |Lat: X   |\           .---.    /--------|Database A|
               |Long: Y  | \         (     )  /         ------------
               -----------  \-------/       \/               o
                                   ( Internet)               o
               -----------  /------(         )\              o
               | Master  | /        (       )  \             o
               |WS Device|/          (_____)    \       ------------
               |Lat: X   |                       \------|Database B|
               |Long: Y  |                              ------------
               -----------
    Figure 1: High-Level View of White-Space Database Architecture
 Note that there could be multiple databases serving white-space
 devices.  In some countries, such as the U.S., the regulator has
 determined that multiple 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.

3.1. Global Applicability

 The use of white-space spectrum is currently approved or being
 considered in multiple regulatory domains, whose rules may differ.
 However, the need for devices that intend to use the spectrum to
 communicate with a database remains a common feature.  The database

Mancuso, et al. Informational [Page 6] RFC 6953 PAWS Use Cases and Requirements May 2013

 implements rules that protect all primary users, independent of the
 characteristics of the white-space devices.  It also provides a way
 to specify a schedule of use, since some primary users (for example,
 wireless microphones) only operate in limited time slots.
 Devices need to be able to query a database, directly or indirectly,
 over the public Internet and/or private IP networks prior to
 operating in available spectrum.  Information about available
 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.  Interface agnostic - An interface between a master white-space
     device and database can be wired or unwired (e.g., a radio/air
     interface technology such as IEEE 802.11af, IEEE 802.15.4m, IEEE
     802.16, IEEE 802.22, LTE, etc.)  However, the messaging interface
     between a master white-space device and the database should be
     agnostic to the interface used for such messaging while being
     cognizant of the characteristics of the interface technology and
     the need to include any relevant attributes in the query to the
     database.
 2.  Spectrum agnostic - The spectrum used by primary and secondary
     users varies by country.  Some spectrum bands have 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 primary and secondary 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 location where such spectrum is available and a common
     interface ensures uniformity in implementations and deployment.
     To allow the global use of white-space devices in different
     countries (whatever the regulatory domain), the protocol should
     support the database that communicates the applicable regulatory
     rule-set information to the white-space device.
 4.  Built on flexible and extensible data structures - Different
     databases are likely to have different requirements for the kinds
     of data required for registration (different regulatory rule sets
     that apply to the registration of devices) and other messages
     sent by the device to the database.  For instance, different
     regulators might require different device-characteristic
     information to be passed to the database.

Mancuso, et al. Informational [Page 7] RFC 6953 PAWS Use Cases and Requirements May 2013

3.2. Database Discovery

 The master device must obtain the address of a trusted database,
 which it will query for available white-space spectrum.  If the
 master device uses a discovery service to locate a trusted database,
 it may perform the following steps (this description is intended as
 descriptive, not prescriptive):
 1.  The master device constructs and sends a request (e.g., over the
     Internet) to a trusted discovery service.
 2.  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.  If so, it establishes contact
     with the trusted database.
 3.  The master device establishes a white-space network as described
     in Section 4.
 Optionally, and in place of steps 1-2 above, the master device can be
 pre-configured with the address (e.g., URI) of one or more trusted
 databases.  The master device can establish contact with one of these
 trusted databases.

3.3. Device Registration

 The master device may register with the database before it queries
 the database for available spectrum.  A registration process may
 consist of the following steps:
 1.  The master device sends registration information to the database.
     This information may include the device ID; serial number
     assigned by the manufacturer; device location; device antenna
     height above ground; name of the individual or business that owns
     the device; and the name, postal address, email address, and
     phone number of a contact person responsible for the device's
     operation.
 2.  The database responds to the registration request with an
     acknowledgment to indicate the success of the registration
     request or with an error if the registration was unsuccessful.
     Additional information may be provided by the database in its
     response to the master device.

Mancuso, et al. Informational [Page 8] RFC 6953 PAWS Use Cases and Requirements May 2013

3.4. Protocol

 A protocol that enables a white-space device to query a database to
 obtain information about available spectrum 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.

3.5. Data Model Definition

 The contents of the queries and response need to be specified.  A
 data model is required; it must enable 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, 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.

4. Use Cases

 There are many potential use cases for white-space spectrum -- for
 example, providing broadband Internet access in urban and densely
 populated hotspots, as well as rural and remote, underserved areas.
 Available white-space spectrum may also be used to provide Internet
 'backhaul' for traditional Wi-Fi hotspots or for use by towns and
 cities to monitor/control traffic lights, read utility meters, and
 the like.  Still other use cases include the ability to offload data
 traffic from another Internet access network (e.g., 3G cellular
 network) or to deliver data, information, or a service to a user
 based on the user's location.  Some of these use cases are described
 in the following sections.

4.1. Master-Slave White-Space Networks

 There are a number of common scenarios in which a master white-space
 device will act as proxy or mediator for one or more slave devices
 using its connection to the Internet to query the database for
 available spectrum for itself and for one or more slave devices.
 These slave devices may be fixed or mobile, in close proximity with
 each other (indoor network or urban hotspot), or at a distance (rural
 or remote WAN).  Once slave devices switch to white-space spectrum
 for their communications, they may connect through the master to the
 Internet or use white-space spectrum for intra-network communications
 only.  The master device can continue to arbitrate and control white-
 space communications by slave devices, and it may notify them when
 they are required to change white-space frequencies or cease white-
 space communications.

Mancuso, et al. Informational [Page 9] RFC 6953 PAWS Use Cases and Requirements May 2013

 Figure 2 depicts the general architecture of such a simple master-
 slave network in which the master device communicates with a database
 on its own behalf and on behalf of slave devices.
  1. ——-

|Slave |

        |Device| \             \|/                          ----------
        |  1   |  (Air)         |                           |Database|
        --------       \        |                 (----)   /|--------|
           |            \ ------|------          (      ) /
           |             \|  Master   |         /        \
         --------        /|           |======= ( Internet )
         |Slave |       / |  Device   |         \        /
         |Device|  (Air)  |           |          (      )
         |  2   | /       |-----------|           (----)
         --------        /
           o   |        /
           o   |     (Air)
           o   |      /
         --------    /
         |Slave |   /
         |Device|  /
         |  n   |
         --------
              Figure 2: Master-Slave White-Space Network
 The protocol requirements for these master-slave devices and other
 similar scenarios is essentially the same: the protocol must support
 the ability of a master device to make available-spectrum query
 requests on behalf of slave devices, passing device identification,
 geolocation, and other slave device parameters to the database as
 required to obtain a list of white-space spectrum available for use
 by one or more slave devices.  Of course, different use cases will
 use this spectrum information in different ways, and the details of
 master/slave communications may be different for different use cases.
 Common steps that may occur in master-slave networks include the
 following:
 1.  The master device powers up.
 2.  Slave devices may power up and associate with the master device
     via Wi-Fi or some other over-the-air, non-white-space spectrum.
     Until the slave device is allocated white-space spectrum, any
     master-slave or slave-slave communications occurs over such non-
     white-space spectrum.

Mancuso, et al. Informational [Page 10] RFC 6953 PAWS Use Cases and Requirements May 2013

 3.  The master has Internet connectivity, determines (or knows) its
     location, and establishes a connection to a trusted database (see
     Section 3.2).
 4.  The master may register with the trusted database (see
     Section 3.3).
 5.  The master sends a query to the trusted database requesting a
     list of available white-space spectrum based upon its
     geolocation.  Query parameters may include the master's location,
     device identifier, and antenna height.  The master may send
     available-spectrum requests to the database on behalf of slave
     devices.
 6.  The database responds to the master's query with a list of
     available white-space spectrum, associated maximum power levels,
     and durations of time for spectrum use.  If the master made
     requests on behalf of slave devices, the master may transmit the
     obtained available-spectrum lists to the slaves (or the master
     may allocate spectrum to slaves from the obtained spectrum
     lists).
 7.  The master may inform the database of the spectrum and power
     level it selects from the available spectrum list.  If a slave
     device has been allocated available white-space spectrum, the
     slave may inform the master of the spectrum and power level it
     has chosen, and the master may, in turn, relay such slave device
     usage to the database.
 8.  Further communication among masters and slaves over the white-
     space network may occur via the selected/allocated white-space
     spectrum frequencies.
 Note: Steps 5 through 7 may be repeated by the master device when it
 (or a slave device that uses the master as a proxy to communicate
 with the database) changes its location or operating parameters --
 for example, after a master changes location, it may query the
 database for available spectrum at its new location, then acknowledge
 the subsequent response received from the database with information
 on the spectrum and power levels it is using at the new location.

4.2. Offloading: Moving Traffic to a White-Space Network

 This scenario is a variant of the master-slave network described in
 the previous use case.  In this scenario, an access point (AP) offers
 a white-space service that offloads Internet traffic as an
 alternative data path to a more congested or costly Internet wire,
 wireless, or satellite service.

Mancuso, et al. Informational [Page 11] RFC 6953 PAWS Use Cases and Requirements May 2013

 Figure 3 shows an example of deployment of this scenario.
                            \|/
                             |
                          |--|----------|
        \|/              /|Access Point |\
         |       (Air)--/ |-------------| \
       --|------ /                         \               -----------
      |Portable|/                           \      (----)  | Database|
      | Device |                             \    (      ) /----------
      |--------|\                             \  /        \
                 \                             X( Internet )
                  \                           /  \        /
                   (Air)                     /    (      )
                      \                     /      (----)
                       \                   /
                        \|---------------|/
                         |    Metered    |
                         |    Service    |
                         |---------------|
         Figure 3: Offloading Traffic to a White-Space Network
 A simplified operation scenario of offloading content, such as video
 stream, from a congested or costly Internet connection to a white-
 space service provided by an AP consists of the following steps:
 1.  The AP contacts the database to determine channels it can use.
 2.  The portable device connects to a paid Internet service and
     selects a video for streaming.
 3.  The portable device determines if it can offload to a white-space
     AP:
     A.  If the portable device knows its location, it
         1.  asks the database (using the paid service) for available
             white-space spectrum;
         2.  listens for and connects to the AP over the permitted
             white-space spectrum.
     B.  If the portable device does not have GPS or other means to
         determine its position, it
         1.  uses non-white-space spectrum to listen for and connect
             to the AP;

Mancuso, et al. Informational [Page 12] RFC 6953 PAWS Use Cases and Requirements May 2013

         2.  asks the AP to query the database for permitted white-
             space spectrum on its behalf;
         3.  uses the permitted white-space spectrum to connect to the
             AP.
 4.  The portable device accesses the Internet through the AP to
     stream the selected video.

4.3. White Space Serving as Backhaul

 In this use case, an Internet connectivity service is provided to
 users over a common wireless standard, such as Wi-Fi, with a white-
 space master/slave network providing backhaul connectivity to the
 Internet.  Note that Wi-Fi is referenced in Figure 4 and the
 following discussion, but any other technology can be substituted in
 its place.
 Figure 4 shows an example of deployment of this scenario.
                       \|/   White      \|/    \|/     Wi-Fi \|/
                        |    Space       |      |             |
                        |                |      |           |-|----|
          (----)      |-|----|         |-|------|-|         | Wi-Fi|
         (      )     |Master|         | Slave    |--(Air)--| Dev  |
        /        \    |      |--(Air)--| Bridge   |         |------|
       ( Internet )---|      |         | to Wi-Fi |
        \        /    |------|         |----------|           \|/
         (      )                                  \           |
          (----)                                    \(Air)   |-|----|
                                                          \--| Wi-Fi|
                                                             | Dev  |
                                                             |------|
            Figure 4: White-Space Network Used for Backhaul
 Once the bridged device (Slave Bridge + 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 slave device (Slave Bridge + Wi-Fi) is connected to a
     master device operating in the WS spectrum (the master obtains
     available white-space spectrum as described in Section 4.1).
 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.

Mancuso, et al. Informational [Page 13] RFC 6953 PAWS Use Cases and Requirements May 2013

4.4. Rapid Network Deployment during Emergencies

 Organizations involved in handling emergency operations maintain an
 infrastructure that relies on dedicated spectrum for their
 operations.  However, such infrastructures are often affected by the
 disasters they handle.  To set up a replacement network, spectrum
 needs to be quickly cleared and reallocated to the crisis response
 organization.  Automation of this allocation and assignment is often
 the best solution.  A preferred option is to make use of a robust
 protocol that has been adopted and implemented by radio
 manufacturers.  A typical network topology solution might include
 wireless access links to the public Internet or private network,
 wireless ad hoc network radios working independently of a fixed
 infrastructure, and satellite links for backup where lack of
 coverage, overload, or outage of wireless access links can occur.
 Figure 5 shows an example of deployment of this scenario.
                              \|/
                               | ad hoc
                               |
                             |-|-------------|
                             | Master node   |    |-------------|
        \|/                  | with          |    | White-Space |
         | ad hoc           /| backhaul link |    | Database    |
         |             /---/ |---------------|    |-------------|
      ---|------------/                |      \           /
      | Master node   |                |       |      (--/--)
      | without       |                |        -----(       )
      | backhaul link |                |  Wireless  / Private \
      ----------------\                |    Access (   net or  )
                       \                |           \ Internet )
                        \    \|/        |      ------(        /
                         \    | ad hoc  |      |      (------)
                          \   |         |      /          \
                           \--|-------------  /Satellite   ----------
                           | Master node   | / Link        | Other  |
                           | with          |/              | nodes  |
                           | backhaul link |               ----------
                           -----------------
    Figure 5: Rapidly Deployed Network with Partly Connected Nodes
 In the ad hoc network, all nodes are master nodes that allocate radio
 frequency (RF) channels from the database (as described in
 Section 4.1).  However, the backhaul link may not be available to all
 nodes, such as depicted for the left node in the above figure.  To
 handle RF channel allocation for such nodes, a master node with a

Mancuso, et al. Informational [Page 14] RFC 6953 PAWS Use Cases and Requirements May 2013

 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.

4.5. White Space Used for Local TV Broadcaster

 Available white-space spectrum can be deployed in novel ways to
 leverage the public use of hand-held and portable devices.  One such
 use is white-space spectrum used for local TV transmission of audio-
 video content to portable devices used by individuals in attendance
 at an event.  In this use case, audience members at a seminar,
 entertainment event, or other venue plug a miniature TV receiver fob
 into their laptop, computer tablet, cell phone, or other portable
 device.  A master device obtains a list of available white-space
 spectrum (as described in Section 4.1), then broadcasts audio-video
 content locally to the audience over one of the available
 frequencies.  Audience members receive the content through their
 miniature TV receivers tuned to the appropriate white-space band for
 display on the monitors of their portable devices.
 Figure 6 shows an example of deployment of this scenario.
                                              |------------|
                                              |White-Space |
                                              | Database   |
                                    .---.   / |------------|
            |-----------|          (     ) /
            |  Master   |         /       \
            |           |========( Internet)
            |-----------|         \       /
                  |                (     )
                 /|\                (---)
            (White-Space
             Broadcast)
       \|/   \|/   \|/   \|/   \|/   \|/   \|/
        |     |     |     |     |     |     |     .................
      ----- ----- ----- ----- ----- ----- -----
      |   | |   | |   | |   | |   | |   | |   |
      |   | |   | |   | |   | |   | |   | |   |
      ----- ----- ----- ----- ----- ----- -----
     USB TV receivers connected to laptops, cell phones, tablets ...
           Figure 6: White Space Used for Local TV Broadcast

Mancuso, et al. Informational [Page 15] RFC 6953 PAWS Use Cases and Requirements May 2013

5. Requirements

5.1. Data Model Requirements

 D.1  The data model MUST support specifying the geolocation of the
      white-space device, the uncertainty in meters, the height and
      its uncertainty, and the percentage of confidence in the
      location determination.  The data model MUST support [WGS84].
 D.2  The data model MUST support specifying the data and other
      applicable requirements of the rule set that applies to the
      white-space device at a specified location.
 D.3  The data model MUST support device description data that
      identifies a white-space device (serial number, certification
      IDs, etc.) and describes device characteristics, such as device
      class (fixed, mobile, portable, indoor, outdoor, etc.), Radio
      Access Technology (RAT), etc.
 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 white-space device, such as:
         antenna height
         antenna gain
         maximum output power, Equivalent Isotropic Radiated Power
         (EIRP) in dBm (decibels referenced to 1 milliwatt)
         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 (decibels referenced to an arbitrary
         reference level) 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 and the name, postal address, email
      address, and phone number of the transmitter operator.

Mancuso, et al. Informational [Page 16] RFC 6953 PAWS Use Cases and Requirements May 2013

 D.7  The data model MUST support specifying spectrum availability.
      Spectrum units are specified by low and high frequencies and may
      have an optional channel identifier.  The data model MUST
      support a schedule including start time and stop time for
      spectrum unit availability.  The data model MUST support maximum
      power level for each spectrum unit.
 D.8  The data model MUST support specifying spectrum 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 white-space device in the
      acknowledgment message.

5.2. Protocol Requirements

 P.1   The master device identifies a database to which it can
       register, make spectrum availability requests, etc.  The
       protocol MUST support the discovery of an appropriate database
       given a location provided by the master device.  The master
       device MAY select a database by discovery at run time or by
       means of a pre-programmed URI.  The master device MAY validate
       discovered or configured database addresses against a list of
       known databases (e.g., a list of databases approved by a
       regulatory body).
 P.2   The protocol MUST support the database informing the master of
       the regulatory rules (rule set) that applies to the master
       device (or any slave devices on whose behalf the master is
       contacting the database) at a specified location.
 P.3   The protocol MUST provide the ability for the database to
       authenticate the master device.
 P.4   The protocol MUST provide the ability for the master device to
       verify the authenticity of the database with which it is
       interacting.
 P.5   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.6   The protocol MUST provide the capability for messages sent by
       the master device and database to be encrypted.

Mancuso, et al. Informational [Page 17] RFC 6953 PAWS Use Cases and Requirements May 2013

 P.7   Tracking of master or slave device uses of white-space spectrum
       by database administrators, regulatory agencies, and others who
       have access to a white-space database could be considered
       invasive of privacy, including privacy regulations in specific
       environments.  The PAWS protocol SHOULD support privacy-
       sensitive handling of device-provided data where such
       protection is feasible, allowed, and desired.
 P.8   The protocol MUST support the master device registering with
       the database; see Device Registration (Section 3.3).
 P.9   The protocol MUST support a registration acknowledgment
       indicating the success or failure of the master device
       registration.
 P.10  The protocol MUST support an available spectrum request from
       the master device to the database, which may include one or
       more of the data items listed in Data Model Requirements
       (Section 5.1).  The request may include data that the master
       device sends on its own behalf and/or on behalf of one or more
       slave devices.
 P.11  The protocol MUST support an available spectrum response from
       the database to the master device, which may include one or
       more of the data items listed in Data Model Requirements
       (Section 5.1).  The response may include data related to master
       and/or slave device operation.
 P.12  The protocol MUST support a spectrum usage message from the
       master device to the database, which may include one or more of
       the data items listed in Data Model Requirements (Section 5.1).
       The message may include data that the master device sends on
       its own behalf and/or on behalf of one or more slave devices.
 P.13  The protocol MUST support a spectrum usage message
       acknowledgment.
 P.14  The protocol MUST support a validation request from the master
       device to the database to validate a slave device, which should
       include information necessary to identify the slave device to
       the database.
 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 database.  The validation response MUST
       indicate the success or failure of the validation request.

Mancuso, et al. Informational [Page 18] RFC 6953 PAWS Use Cases and Requirements May 2013

 P.16  The protocol MUST support the capability for the database to
       inform master devices of changes to spectrum availability
       information.

5.3. Operational Requirements

 This section contains operational requirements of a database-device
 system, independent of the requirements of the protocol for
 communication between the database and devices.
 O.1  The master device must be able to connect to the database to
      send requests to the database and receive responses to, and
      acknowledgments of, its requests from the database.
 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.
 O.3  The master device MUST be configured to understand and comply
      with the requirements of the rule set of the regulatory body
      that apply to its operation at its location.
 O.4  A master device MUST query the database for the available
      spectrum at a specified location before starting radio
      transmission in white space at that location.
 O.5  A master device MUST be able to query the database for the
      available spectrum on behalf of a slave device at a specified
      location before the slave device starts radio transmission in
      white space at that location.
 O.6  The database MUST respond to an available spectrum request.

5.4. Guidelines

 White-space technology itself is expected to evolve and include
 attributes such as coexistence 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
     messaging-specific, administrative-specific, and spectrum-
     specific parts into distinct modules.
 2.  The protocol SHOULD support determination of which
     administrative-specific and spectrum-specific modules are used.

Mancuso, et al. Informational [Page 19] RFC 6953 PAWS Use Cases and Requirements May 2013

6. Security Considerations

 PAWS is a protocol whereby a master device requests a schedule of
 available spectrum at its location (or the location of its slave
 devices) before it (or they) can operate using those frequencies.
 Whereas the information provided by the database must be accurate and
 conform to applicable regulatory rules, the database cannot enforce,
 through the protocol, that a client device uses only the spectrum it
 provided.  In other words, devices can put energy in the air and
 cause interference without asking the database.  Hence, PAWS security
 considerations do not include protection against malicious use of the
 white-space spectrum.
 Threat model for the PAWS protocol:
    Assumptions:
       The link between the master device and the database can be
       wired or wireless and provides IP connectivity.  It is assumed
       that an attacker has full access to the network medium between
       the master device and the database.  The attacker may be able
       to eavesdrop on any communications between these entities.
    Threat 1: User modifies a device to masquerade as another valid
    certified device
       A master device identifies itself to the database in order to
       obtain information about available spectrum.  Without suitable
       protection mechanisms, devices can listen to registration
       exchanges and later register with the database by claiming the
       identity of another device.
    Threat 2: Spoofed database
       A master device attempts to discover a database (or databases)
       that it can query for available spectrum information.  An
       attacker may attempt to spoof a database and provide responses
       to a master device that are malicious and result in the master
       device causing interference to the primary user of the
       spectrum.
    Threat 3: Modifying or jamming a query request
       An attacker may modify or jam the query request sent by a
       master device to a database.  The attacker may change the
       location of the device or its capabilities (transmit power,
       antenna height, etc.), and, as a result, the database responds
       with incorrect information about available spectrum or maximum

Mancuso, et al. Informational [Page 20] RFC 6953 PAWS Use Cases and Requirements May 2013

       transmit power allowed.  The result of such an attack is that
       the master device can cause interference to the primary user of
       the spectrum.  It may also result in a denial of service to the
       master device if the modified database response indicates that
       no channels are available to the master device or when a jammed
       query prevents the request from reaching the database.
    Threat 4: Modifying or jamming a query response
       An attacker may modify or jam the query response sent by the
       database to a master device.  For example, an attacker may
       modify the available spectrum or power-level information
       carried in the database response.  As a result, a master device
       may use spectrum that is not available at a location or may
       transmit at a greater power level than allowed.  Such
       unauthorized use can result in interference to the primary user
       of that spectrum.  Alternatively, an attacker may modify a
       database response to indicate that no spectrum is available at
       a location (or jam the response), resulting in a denial of
       service to the master device.
    Threat 5: Third-party tracking of white-space device location and
    identity
       A master device may 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
       unauthorized tracking purposes.
    Threat 6: Malicious individual acts as a database to terminate or
    unfairly limit spectrum access of devices
       A database may include a mechanism by which service and
       spectrum allocated to a master device can be revoked by sending
       a revoke message to a master device.  A malicious user can
       pretend to be a database and send a revoke message to that
       device.  This results in denial of service to the master
       device.
 The security requirements arising from the above threats are captured
 in the requirements of Section 5.2.

Mancuso, et al. Informational [Page 21] RFC 6953 PAWS Use Cases and Requirements May 2013

7. Acknowledgments

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

8. References

8.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [WGS84]    National Imagery and Mapping Agency, "Department of
            Defense World Geodetic System 1984, Its Definition and
            Relationships with Local Geodetic Systems", NIMA
            TR8350.2 Third Edition Amendment 1, January 2000,
            <http://earth-info.nga.mil/GandG/publications/tr8350.2/
            wgs84fin.pdf>.

8.2. Informative References

 [CRADIO]   Cognitive Radio Technologies Proceeding (CRTP), "Federal
            Communications Commission", ET Docket No. 03-108,
            August 2010, <http://fcc.gov/oet/cognitiveradio>.
 [PAWS]     Chen, V., Ed., Das, S., Zhu, L., Malyar, J., and P.
            McCann, "Protocol to Access Spectrum Database", Work
            in Progress, May 2013.

Mancuso, et al. Informational [Page 22] RFC 6953 PAWS Use Cases and Requirements May 2013

Authors' Addresses

 Anthony Mancuso (editor)
 Google
 1600 Amphitheatre Parkway
 Mountain View, CA  94043
 US
 EMail: amancuso@google.com
 Scott Probasco
 EMail: scott@probasco.me
 Basavaraj Patil
 Cisco Systems
 2250 East President George Bush Highway
 Richardson, TX  75082
 US
 EMail: basavpat@cisco.com

Mancuso, et al. Informational [Page 23]

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