Protocol to query a White Space Database
draft-caufield-paws-protocol-for-tvws-01.txt

Abstract

Regulatory entities in many countries are making spectrum previously used by television stations available for secondary use as a result of the switch from analog to digital. The spectrum in such cases is still owned by the primary user to whom it is licensed. However parts of the spectrum may be unused at a given location or time and hence can be made available for secondary use. In order to use such spectrum a device has to query a database in order to obtain a list of available channels or spectrum at a given location and time. This document specifies protocol elements that can be used to query a white space database and obtain a response by a device.

Status of this Memo

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This Internet-Draft will expire on May 03, 2012.

Copyright Notice

Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Introduction
• 2. Terminology and Abbreviations
• 3. Background
• 4. Problem Statement
• 5. Protocol approach
• 6. Data Model details
• 6.1. White Space Query Object
• 6.1.1. Query object definition
• 6.2. White Space Response Object
• 6.2.1. Response Object Definition
• 6.3. Elements of the Query and Response objects
• 6.3.1. Station element
• 6.3.2. Schedule element
• 6.3.3. ChannelList element
• 6.3.4. ContactList element
• 6.3.5. Location element
• 6.3.6. Antenna element
• 6.3.7. StationRxList element
• 6.3.8. TransmitterList element
• 6.3.9. Address element
• 6.3.10. Coordinate element
• 6.3.11. RadiationPattern element
• 6.3.12. Contact Element
• 6.3.13. Extension element
• 6.3.14. WhiteSpaceFrequencyList element
• 6.3.15. WhiteSpaceFrequency element
• 6.3.16. Channel Element
• 6.3.17. Transmitter Element
• 6.4. Attributes definition
• 7. IANA Considerations
• 8. Security Considerations
• 9. Acknowledgements
• 10. References
• 10.1. Normative References
• 10.2. Informative References
• Author's Address

1. Introduction

Regulatory entities in many countries are making spectrum previously used by television stations available for secondary use as a result of the switch from analog to digital. The spectrum in such cases is still owned by the primary user to whom it is licensed. However parts of the spectrum may be unused at a given location or time and hence can be made available for secondary use. In order to use such spectrum a device has to query a database in order to obtain a list of available channels or spectrum at a given location and time. This document specifies protocol elements that can be used to query a white space database and obtain a response by a device.

The problem statement, use cases and requirements for the use of white space spectrum and the associated protocol is captured in the document: [I-D.ietf-paws-problem-stmt-usecases-rqmts].

2. Terminology and Abbreviations

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 [RFC2119].

This document relies on the terminology specified in [I-D.ietf-paws-problem-stmt-usecases-rqmts].

3. Background

Spectrum is a scarce resource and hence it is essential that technology provide a means to use this resource in an optimal manner. Spectrum has been generally licensed or granted or reserved for specific use by regulatory bodies and governments. Some spectrum such as the ISM band has been made publicly available for use without any licenses but still with a set of regulations. In many cases spectrum that has been licensed to an entity or reserved is either not utilized or under utilized. As the demand for services over wireless medium continues to grow the need for additional spectrum is increasing. Cognitive radio and white space technology is a solution that allows the use of spectrum by a secondary user at a given location if the primary user is either not using the spectrum at a given time and without causing interference to the primary user. Regualtions to this effect have been specified by the FCC in the US and other regulatory bodies in many other countries are also studying similar approaches for parts of the spectrum.

One of the approaches to determining if spectrum is available at a given location and time is to query a centralized database and obtain information about what channels or spectrum can be used. There may exist multiple databases from which such information can be obtained. A standardized query/response mechanism is in the scope of the PAWS working group. This document proposes a data format for the query and response aspects of the protocol.

4. Problem Statement

The query/response protocol to obtain information about available channels or spectrum can be specified using various means. LDAP is an example of a protocol that can be used for this purpose. However one of the objectives of this protocol is to ensure that it is globally applicable and can be adapted for use in various regulatory environments. The elements of the query and response can vary depending on the country or region where a device is making a query to a database. As a result of this objective, flexibility of the protocol in terms of the attributes and parameters carried in the query and response are quite important.

5. Protocol approach

This document does not specify the complete protocol itself. The protocol can be split into three parts:

1. The data model
2. The transport protocol
3. The security solution

A data model for the query/response protocol is proposed in this document. A hierarchical object model approach is used for defining the query/response and its attributes. The figure below is a high-level view of how the data model is structured:

	                   -------------
	    		   |WS Protocol|
			   -------------
				 |
				 |
		 -------------------------------------
	    	 |                                   |
	    ---------                            ------------
	    |wsQuery|  				 |wsResponse|
	    --------- 				 ------------
		|      	       	       	       	       |
	    ----------				  ----------
	    |Element1| ...5, 6, 7                 |Elementx| ... y,z
	    ----------	  .  . 	.	       	  ----------	 . .
	       	|	  .  .	.      	       	       |       	 . .
       	    ------------  .  .	.      	       	  ------------	 . .
	    |Attributes| o o o o o     	       	  |Attributes| o o o
	    ------------	  		  ------------

           

6. Data Model details

The data model includes two main objects, the wsQuery and wsResponse objects. Each of these objects contain a list of elements. The elements are further comprised of attributes. The wsQuery object is sent by a WS Master device to a database and the database responds with a wsResponse object. The actual message and header in which this object is carried is not specified here and is expected to be specified elsewhere. Neither does this document specify how the device discovers the database or how the object is transported or secured.

6.1. White Space Query Object

The whitespaceQuery object is a data object carried in a request message that any white space client (e.g. a white space device, software application, coexistence manager, etc.) may use to request information from a white space database, as part of a Rules-compliant data transaction.

6.1.1. Query object definition

<xs:complexType name="whitespaceQuery">
		<xs:all>
			<xs:element name="station" 	type="station"/>
			<xs:element name="schedule" 	type="schedule" minOccurs="0"/>
			<xs:element name="extension" 	type="xs:string" minOccurs="0"/>
		</xs:all>
		<xs:attribute name="uuid" 		type="xs:string" use="required"/>
		<xs:attribute name="protocolVersion" 	type="xs:float" use="required"/>
		<xs:attribute name="messageType" 	type="xs:string" use="required"/>
</xs:complexType>

               

6.2. White Space Response Object

A whitespaceResponse object is a generalized message response structure that any white space administrator (e.g. a white space database implementation) may use to communicate white space information in a Rules-compliant data transaction.

The whitespaceResponse object structure is intended to accommodate various responses to information queries from different white space client such as, for example, white space devices (for transmission), management systems (not for transmission) and consumers (not for transmission).

6.2.1. Response Object Definition

<xs:complexType name="whitespaceResponse">
		<xs:sequence>
			<xs:element name="station" 	type="station"/>
			<xs:element name="whitespaceFrequencyList" type="whitespaceFrequency" 
				    nillable="true" minOccurs="1" maxOccurs="unbounded"/>
			<xs:element name="extension" 	type="xs:string" minOccurs="0"/>
		</xs:sequence>
		<xs:attribute name="uuid" 	type="xs:string" use="required"/>
		<xs:attribute name="effectiveDate" 	type="xs:dateTime" use="required"/>
		<xs:attribute name="expirationDate" 	type="xs:dateTime" use="required"/>
		<xs:attribute name="messageType" 	type="xs:string" use="required"/>
		<xs:attribute name="protocolVersion" 	type="xs:float" use="required"/>
		<xs:attribute name="statusIndicator" 	type="xs:int" use="required"/>
		<xs:attribute name="timeStamp" 	type="xs:dateTime" use="required"/>
</xs:complexType>

       

6.3. Elements of the Query and Response objects

The whitespaceQuery and whitespaceResponse objects include multiple elements. Some of the elements are common across the query and response objects. The following sections define these elements.

6.3.1. Station element

A WSIF station object contains information about the inquiring station including antenna, location, transmitter details, etc.

<xs:complexType name="station">
		<xs:sequence>
			<xs:element name="channelList"	type="channel" maxOccurs="unbounded"/>
			<xs:element name="contactList"	type="contact" maxOccurs="unbounded"/>
			<xs:element name="location"	type="location"/>
			<xs:element name="antenna"	type="antenna" minOccurs="0"/>
			<xs:element name="schedule"	type="schedule" minOccurs="0"/>
			<xs:element name="stationRxList"	
				    type="station" minOccurs="0" maxOccurs="unbounded"/>
			<xs:element name="transmitterList"	
				    type="transmitter" minOccurs="0" maxOccurs="unbounded"/>
			<xs:element name="extension"	
				    type="xs:string" minOccurs="0"/>
			<xs:element name="x-licenseInformationList"
			
				    type="licenseInformation" 
				    minOccurs="0" maxOccurs="unbounded"/>
		</xs:sequence>
		<xs:attribute name="uuid"	type="xs:string" use="required"/>
		<xs:attribute name="name"	type="xs:string" use="required"/>
		<xs:attribute name="stationClass"	type="xs:string" use="required"/>
		<xs:attribute name="description"	type="xs:string"/>
		<xs:attribute name="stationType"	type="xs:string"/>
	</xs:complexType>
       

6.3.2. Schedule element

Type: Schedule

A schedule object is used by white space devices to request temporary spectrum access (i.e. less than 24 hours). The schedule element is intended to enable the recording, persistence and distribution of standardized iCalendar-compatible messages. The format of the Schedule object is defined in [RFC5545].

6.3.3. ChannelList element

Type: Channel

A list of channels (i.e. frequency ranges) that are occupied by the transmitter(s) at this station.

6.3.4. ContactList element

Type: Contact

A list of contacts associated with this station. For example, a facility or on-site technical manager, administrator, and operational contacts may be identified.

6.3.5. Location element

This element describes the station's physical and geographic location.

<xs:complexType name="location">
		<xs:all>
			<xs:element name="address" 	type="address" minOccurs="0"/>
			<xs:element name="coordinate" 	type="coordinate" minOccurs="0"/>
		</xs:all>
		<xs:attribute name="uuid" 	type="xs:string" use="required"/>
		<xs:attribute name="name" 	type="xs:string" use="required"/>
		<xs:attribute name="locationType" 	type="xs:string"/>
		<xs:attribute name="x-geocode" 	type="xs:string"/>
		<xs:attribute name="x-haat" 	type="xs:float"/>
		<xs:attribute name="x-timeZone" 	type="xs:string"/>
</xs:complexType>
       

6.3.6. Antenna element

A description of this station’s (transmit or receive) antenna, including the required antenna parameters like pointing and elevation information plus the radiation pattern.

<xs:complexType name="antenna">
		<xs:sequence>
			<xs:element name="radiationPattern" 	type="radiationPattern"/>
		</xs:sequence>
		<xs:attribute name="directional" 		type="xs:boolean" use="required"/>
		<xs:attribute name="rotation" 			type="xs:float" use="required"/>
		<xs:attribute name="heightAboveGround" 		type="xs:float" use="required"/>
		<xs:attribute name="manufacturer" 		type="xs:string"/>
		<xs:attribute name="model" 			type="xs:string"/>
		<xs:attribute name="x-elevationModel" 		type="xs:string"/>
		<xs:attribute name="x-govtAntennaId" 		type="xs:int"/>
		<xs:attribute name="x-haat" 			type="xs:float"/>
		<xs:attribute name="x-rcAmsl" 			type="xs:float"/>
	</xs:complexType>
       

6.3.7. StationRxList element

Type: Station

For wireless services that include multiple stations, and especially for wireless services with multiple TXRX stations, each receiving station may indicate its respective upstream transmitting stations by adding that transmitting station to this receiving stationís rxStationList element. Example uses of this element include Television translator stations, MVPD receive sites, etc.

6.3.8. TransmitterList element

Type: Transmitter

A station may support multiple transmitters operating within the same geographic area and on the same schedule. For example, several wireless microphones may operate simultaneously within the geographic contour defined within this stationís location element. If the stationType attribute indicates this station is receive-only then this element SHOULD be null.

6.3.9. Address element

Type: Address

This element specifies the civic location of the station. The structure of this element is described in [RFC5139].

6.3.10. Coordinate element

Type: Coordinate

this element specifies the geolocation of the station. The structure of this element is described in [RFC5491].

6.3.11. RadiationPattern element

Type: RadiationPattern

A radiation pattern representing the directional (azimuth) dependence of the strength of the radio signal from the antenna. The radiationPattern represents the directional (azimuth) dependence of the strength of the radio signal from the antenna.

A WKT MULTIPOINT SFA Geometry implementation. The azimuthal field values are encoded as a well known text (WKT) MULTIPOINT object with [azimuth, radial value] pairs encoded according to the format POINT(x,y) = POINT(azimuth, field_value).

<xs:complexType name="radiationPattern">
		<xs:sequence>
			<xs:element name="radiationPattern" 	type="xs:string"/>
		</xs:sequence>
		<xs:attribute name="source" 			type="xs:string" use="required"/>
		<xs:attribute name="description" 		type="xs:string"/>
		<xs:attribute name="x-interpolated" 		type="xs:boolean"/>
	</xs:complexType>
       

6.3.12. Contact Element

The contact represents a generalized container for individual (person) and company (organization) contact information. The structure of this element is defined in [RFC2426].

6.3.13. Extension element

Type: xs:string

A URL-ENCODED string containing key/value pairs that requesting devices may implement and administrators may support at their discretion to provide supplementary information or to otherwise extend this object.

6.3.14. WhiteSpaceFrequencyList element

Contains a complete and canonical list of available and valid white space frequencies that is appropriate for the inquiring message's criterion. For white space devices, the whitespaceFrequencyList element represents all channels available for unlicensed operation at the inquiring deviceís location or indicated geographic area and according to the schedule in this element.Contains one or more occurencies of WhiteSpaceFrequency elements.

6.3.15. WhiteSpaceFrequency element

<xs:complexType name="whitespaceFrequency">
		<xs:all>
			<xs:element name="channel" 	type="channel"/>
			<xs:element name="location" 	type="location"/>
			<xs:element name="schedule" 	type="schedule"/>
			<xs:element name="extension" 	type="xs:string" minOccurs="0"/>
		</xs:all>
		<xs:attribute name="uuid" 	type="xs:string" use="required"/>
		<xs:attribute name="maxEirp" 	type="xs:float" use="required"/>
</xs:complexType>

       

6.3.16. Channel Element

A channel describes a fully qualified and canonical frequency range. Channel object definitions support positive definitions of colloquial channel identifiers (e.g. TV channel 24) through identification of the authorizing regulatory definition and the TV channelís frequency range.

<xs:complexType name="channel">
		<xs:attribute name="allocation" 	type="xs:string" use="required"/>
		<xs:attribute name="channel" 	type="xs:float" use="required"/>
		<xs:attribute name="minFreq" 	type="xs:double" use="required"/>
		<xs:attribute name="maxFreq" 	type="xs:double" use="required"/>
</xs:complexType>

6.3.17. Transmitter Element

The transmitter object provides an extensible software template to contain and exchange required and optional but otherwise useful transmitter information.

A transmitter provides an object template for common device-related attributes and may be optionally used directly or, more likely, may be extended by other, more specific transmitter descriptions that fully describe a certain type wireless device. For this reason all transmitter attributes and elements are defined as optional by default. Attribute and element validity is expected to be defined in transmitter-derived objects. The transmitter is designed to support, through extension, the communication of required and optional but otherwise useful information about licensed and unlicensed wireless devices including transmitters, receivers and transceivers.

<xs:complexType name="transmitter">
		<xs:sequence>
			<xs:element name="channel"	type="channel" minOccurs="0"/>
			<xs:element name="extension"	type="xs:string" minOccurs="0"/>
		</xs:sequence>
		<xs:attribute name="frequency"	type="xs:double"/>
		<xs:attribute name="deviceId"	type="xs:string"/>
		<xs:attribute name="deviceSn"	type="xs:string"/>
		<xs:attribute name="description"	type="xs:string"/>
		<xs:attribute name="ea"	type="xs:string"/>
		<xs:attribute name="erp"	type="xs:float"/>
		<xs:attribute name="isDigital"	type="xs:boolean"/>
		<xs:attribute name="manufacturer"	type="xs:string"/>
		<xs:attribute name="model"	type="xs:string"/>
		<xs:attribute name="name"	type="xs:string"/>
		<xs:attribute name="x-digitalModRate"	type="xs:double"/>
		<xs:attribute name="x-digitalModType"	type="xs:string"/>
		<xs:attribute name="x-emissionCode"	type="xs:string"/>
		<xs:attribute name="x-equipmentClass"	type="xs:string"/>
		<xs:attribute name="x-equipmentRuleNum"	type="xs:string"/>
		<xs:attribute name="x-maxErp"	type="xs:float"/>
		<xs:attribute name="x-txWidth"	type="xs:float"/>
	</xs:complexType>
       

6.4. Attributes definition

This section defines the attributes which are included in the various elements of the whitespacequery or whitespaceresponse objects.

• Type: xs: boolean
• Description: An indicator for whether the radiationPattern element of this object contains interpolated values.

• Type: xs:string
• Description: The originating source of the data represented in the radiationPattern element. An example value for this attribute is ìus.fcc.cdbsi.

• Type: xs:boolean
• Descrition: Indicates whether the antenna is directional (true) or non-directional (false).

• Type: xs:float
• Description: Indicates the offset in degrees azimuth [0, 360] from true North that the antenna radiation pattern should be rotated.

• Type: xs:float
• Description: The antenna radiation center height above ground level.

• Type: xs:string
• Description: The antenna manufacturer

• Type: xs:string
• Description: The digital elevation model used to calculate this antenna objectís HAAT (x-haat) and rcAMSL (x-rcAmsl) values.

• Type: xs:int
• Description: A reference to the antenna ID record within FCC CDBS

• Type: xs:float
• Description: The antenna height above average terrain

• Type: xs:float
• Description: The antenna radiation center above mean sea level

• Type: xs:double
• Description: If a specific frequency has been assigned to this transmitter that information may be recorded here in MHz. If only the channel is provided then the assignedFrequency value is set to the center frequency of this transmitterís channel.

• Type: xs:string
• Description: The transmitter device's Government provided identifier.

• Type: xs:string
• Description: the transmitting device's manufacturer-provided serial number.

• Type: xs:string
• Description: The Government equipment authorization agency from which this device is authorized to operate and which issued the device ID.

• Type: xs: float
• Description: The transmitting deviceís current effective radiated power (ERP), measured in dBw.

• Type: xs:boolean
• Description: Indicates whether this transmitter is sending a digital (TRUE) or analog (FALSE) carrier.

• Type: xs:string
• Description: the device manufacturer company name

• Type: xs:string
• Description: the antenna product model

• Type: xs:string
• Description:A dot-delimited reverse domain encoded description of the frequency allocation defined according the following strategy:
• [country].[regulator].[allocation].[band range]
• For example, the UHF-high block allocation of TV channels 38 to 51 within the United States is identified as “us.fcc.broadcast.614-698”.

channel attribute

• Type: xs:float
• Description: The colloquial channel number
• Note: A FLOAT number type is used to accommodate future sub-channelization. For the avoidance of doubt channel numbers ending in zero shall be interpreted to represent a whole channel. i.e. float value channel 38.0 is equivalent to integer-value channel 38.

effectiveDate attribute

• Type: xs:dateTime
• Description: The date and time when this white space information should be considered effective. The value may be set in the future to accommodate frequencies that may become available at a later date or time.

expirationDate attribute

• Type: xs:dateTime
• Description: The date and time when this white space information expires.

locationType attribute

• Type: xs:string
• Description: A descriptor string used to classify and organize locations. If the location is derived from another database source, this attribute is a dot-delimited string used to identify this location type and its source. An example value for this attribute is “us.fcc.cdbs.stationClass.CDT”.

maxEIRP attribute

• Type: xs:float
• Description: The maximum allowable equivalent isotripically radiated power (EIRP) that a white space device may transmit on the indicated channel. Provided in dBW.

maxFreq attribute

• Type: xs:double
• Description: The maximum (or end) frequency of the indicated channel in MHz.

messageType attribute

• Type: xs:string
• Description: An enumerated message type. Allowed message types are:
• Message code: ws.messageType.TVBD.QUERY
• Description: The message is a certified client-initiated query for white space frequency information for the purposes of transmission. Examples of certified clients include FCC-certified white space devices and other devices authorized to operate within the band (e.g. wireless microphones, medical telemetry, PLMRS systems, etc.)
• Message code: ws.messageType.TVBD.RESPONSE
• Description: The message is a response to a TVBD.QUERY request for information.
• Message code: ws.messageType.INFORMATION.QUERY
• Description: The message is a non-certified client-initiated query for general (possibly white-space) frequency information NOT for the purposes of transmission. Examples of non-certified clients include network management and planning systems, client software applications, etc.
• Message code: ws.messageType.INFORMATION.RESPONSE
• Description: The message is a response to an INFORMATION.QUERY request for information.

minFreq attribute

• Type: xs:double
• Description: The minimum (or start) frequency of the indicated channel in MHz.

name attribute

• Type: xs:string
• Description: A human readable name or label that may be used to identify a location or station. A useful hint is to use a memorable place name as might be represented on a map (e.g. “Empire State Building”). For licensed wireless services it is recommended to use the facility call sign. For unlicensed wireless services it is recommended to use the venue name.

protocolVersion attribute

• Type: xs:float
• Description: The message protocol version.

stationClass attribute

• Type: xs:string
• Description: Indicates the station classification. Classification may be used to determine whether and how many elements of this station are required for validation. Allowed values are:
• TX. This is a transmitting station and a transmitter is required in the transmitterList element
• RX. This is a receive-only station and a transmitter element is NOT required
• TXRX. This station is able to both transmit and receive and a transmitter is required in the transmitterList element.

stationType attribute

• Type: xs:string
• Description: A description of this station's operation.

statusIndicator attribute

• Type: xs:int
• Description: The number of available white space channels included in the message. A negative value indicates that an error condition has occured.

timeStamp attribute

• Type: xs:dateTime
• Description: When the message was created.

uuid attribute

• Type: xs:string
• Description (for use in Location):A universally unique identifier (UUID) associated with and permanently assigned to this location.
• Description (for use in Station):A universally unique identifier (UUID) associated with and permanently assigned to this station.
• Description (for use in whitespaceFrequency): A universally unique idenfifier (UUID) assigned by an Administrator that is associated with this freuquency
• Description (for use in whitespaceQuery): A universally unique identifier (UUID) created by the inquiring agent (i.e. a TV band device, user software, etc.) and associated with this whitespace query message. This uuid may be used to correlate a whitespaceResponse message with this whitespaceQuery and to simplify logging and archival.
• Description (for use in whitespaceResponse): A universally unique identifier (UUID), set to match the client's whitespaceQuery.uuid attribute and to simplify logging and arhival.

x-geocode attribute

• Type: xs:string
• Description: An enumerated value indicating whether any one of this location object's components have been calculated according to another of this location object's set parameters.
• Allowed values are:
• NO (xs:string) (DEFAULT). The coordinate, address and geometry elements of this location are not correlated.
• GC (xs:string). The coordinate.[longitude, latitude] and geometry.point values have been calculated and set according to a Geo-coding algorithm from the address.
• RG (xs:string). The address has been calculated and set according to a Reverse Geo-coding algorithm from the coordinate.[longitude, latitude] value.

x-haat attribute

• Type: xs:float
• Description: The ground height above average terrain value at this location’s coordinates, calculated according to the methodology described in 47 CFR 73.684(d). The elevation model used in the calculation of this location attribute is recorded in the coordinate.x-elevationModel attribute. This value is used to support TVBD transmit antenna compliance with 15.709(b)(2), which states that the ground level HAAT must be below 76 meters.

x-timeZone attribute

• Type: xs:string
• Description: The local time zone at this location. Two interchangeable formats are supported, with the zoneinfo format preferred:
• The zoneinfo database format (e.g. “America/New_York”)
• An offset to Coordinated Universal Time (e.g. “UTC-05:00” or “UTC-5”
• Note: Three-character notation (e.g. “EDT”) is not supported.

7. IANA Considerations

This document will require actions on the part of IANA to assign values for the new messages and attributes.

8. Security Considerations

This document defines the data model for the database query and response protocol to be used between white space devices and a database. The actual security for the messages that transport these objects needs to be specified in the relevant document.

9. Acknowledgements

This document has been made possible as a result of the efforts of Basavaraj Patil and Scott Probasco.

10. References

10.1. Normative References

10.2. Informative References

Author's Address