PAWS Database Discovery
draft-wei-paws-database-discovery-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Xinpeng Wei , Lei Zhu | ||
| Last updated | 2013-02-17 | ||
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draft-wei-paws-database-discovery-00
Internet Engineering Task Force X. Wei
Internet-Draft L. Zhu
Intended status: Standards Track Huawei
Expires: August 22, 2013 February 18, 2013
PAWS Database Discovery
draft-wei-paws-database-discovery-00
Abstract
This document provides a Database Discovery mechanism for PAWS. By
this mechanism the master device gets the available WSDBs it can
communicate to and the regulatory domain information. The mechanism
is based on LoST protocol .
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 22, 2013.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Conventions . . . . . . . . . . . . . . . . . 3
3. Overview of Architecture . . . . . . . . . . . . . . . . . . . 4
3.1. System Architecture . . . . . . . . . . . . . . . . . . . 7
4. Specification . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Issues to be clarified . . . . . . . . . . . . . . . . . . 9
4.1.1. Service Identifier . . . . . . . . . . . . . . . . . . 9
4.1.2. Conveying of regulatory domain . . . . . . . . . . . . 9
4.2. Discovery procedures . . . . . . . . . . . . . . . . . . . 9
4.2.1. Discovery Request procedure . . . . . . . . . . . . . 10
4.2.2. Discovery Response procedure . . . . . . . . . . . . . 10
4.2.3. Recursion and Iteration . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 12
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative references . . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
In PAWS protocol, the master device queries the database for
available spectrum, but the device MUST determine the URI for the
database before it can send any PAWS messages.
The URI of database can be pre-configured manually in the device
before it sends any PAWS messages, for example, the owner of the
device can configure the URI when he/she wants to use the master
device in certain area. This method needs the owner of the device to
know the available database that can be used in the regulatory
domain.
The URI of database can also be obtained by a dynamic discovery
process, and this is where this document focuses. Before the device
sends any PAWS messages to the database, it first starts a Database
Discovery Procedure to retrieve the available database(s) and
applicable regulatory domain information. This document provides an
optional method for the master device to find an available WSDB.
In discovery procedure, the URI for the database SHOULD be obtained
from an authorized and authenticated entity. The master device
provides its current geo-location information to the entity in
Database Discovery Request message, and the entity will return a list
of available databases and the regulatory body that has jurisdiction
over the master device's location.
When the master device gets the information about available database
and regulatory body, it can choose the proper database for querying
white space spectrum by PAWS procedures.
The database discovery mechanism is based on LoST protocol RFC5222
[RFC5222].
2. Terminology and Conventions
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 [RFC2119].
The terminology from PAWS: problem statement, use cases and
requirements PAWS RQMTS [PAWS RQMTS] is applicable to this document.
White Space Database (WSDB)
In the context of white space and cognitive radio technologies, the
database is an entity which contains, but is not limited to, current
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information as required 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.
White Space Database Discovery Server (WSDB DS)
A server function provided to a white space device, the client. The
white space device contacts a white space database discovery server
to receive the service of discovering or identifying one or more
white space databases. The white space database discovery server is
a known entity to the white space device, which knows at least a
useable internet address for the white space database discovery
server. The white space database discovery server takes as input
positioning information from the white space device and returns both
address information which allows the white space device to contact a
trusted, regulatory-authorized white space database, suitable for
service at the white space device's current location and indication
of the regulatory domain governing at the white space device's
current location. A single white space database discovery server may
have global scope, serving clients located globally.
Service boundary
A service boundary circumscribes the region within which all
locations map to the same service URI or set of URIs for a given
service. A service boundary may consist of several non-contiguous
geometric shapes.
Mapping
Mapping is a process that takes a location and a service identifier
as inputs and returns one or more URIs. Those URIs can point either
to a host providing that service or to a host that in turn routes the
request to the final destination.
3. Overview of Architecture
Before the WSD can query a trusted WSDB for a list of available
frequencies or channels for use in the white space spectrum, the WSD
must first discover the available databases and addresses serving the
regulatory domain in which the device is currently located. At
power-up the WSD does not reliably know the regulatory domain
corresponding to its current location, and therefore does not
reliably know with which white space database(s) it can communicate.
Furthermore it is essential that the WSD connect with a trusted WSDB
for proper operation and indeed regulatory compliance.
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While it is possible that a WSD knows its location, or information
which may be used to derive its location, it is not reasonable for
every WSD to be capable to translate this information into the
current regulatory domain, i.e. the WSD needs assistance to know what
is the regulatory environment with jurisdiction at its current
location.
A WSDB Discovery Server (DS) takes as input location information from
the WSD and returns to the WSD one or more addresses of WSDBs (or
WSDB listing servers as appropriate) to the WSD. If the address or
addresses of these WSDB DSs are included in the WSD firmware, a
secure starting point for a trusted relationship is established.
Figure 1 shows at a high level how white space master devices
discover a suitable trusted white space database. In this document
we describe how the master device may collect the addresses of one or
more white space database. Steps and criteria to sort multiple
addresses into a priority order is left to implementation and not
specified. Procedures to contact a white space database are
specified in PAWS PROTOCOL [PAWS PROTOCOL]. Steps and criteria to
determine the suitability of a particular white space database are
also not considered in this document.
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+-----------------------+
| collect addresses of |
| white space databases |
| |
+-----------------------+
|
|
+-----------------------+
| sort multiple |
| addresses in priority |
| order |
+-----------------------+
|
repeat as needed |
---------------->|
| |
| +-----------------------+
| | contact top priority |
---- | database to determine |
| suitability for |
| service |
+-----------------------+
|
|
end
Figure 1: High level view of white space database discovery
After master device has selected a suitable database for service, it
can then use the PAWS protocol PAWS PROTOCOL [PAWS PROTOCOL] to
retrieve the available spectrum for its location.
An overview of procedures of how master device gets available
spectrum from WSDB is depicted in Figure 2.
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+-----------+ +-----------+ +----------+
| | | WSDB | | |
| WSD | | Discovery | | WSDB |
| | | Server | | |
+-----------+ +-----------+ +----------+
| | |
| Discovery Request | |
|(location information, etc) | |
|--------------------------->| |
| | |
| Discovery Response | |
| (address information, etc) | |
|<---------------------------| |
| | |
| | |
| /--------------------------|-----------------------\ |
|/ channel request | \|
|\ channel response | (PAWS) /|
| \--------------------------|-----------------------/ |
| | |
| | |
Figure 2: An overview of procedures of how master device gets
available spectrum from WSDB
(1) Discovery Request procedure. This message is used by master
device to query available WSDB from WSDB DS; it conveys master's
location and some other related information to WSDB DS.
(2) Discovery Response procedure. This procedure conveys the
regulatory domain and either the address of a listing server or the
address of one or more WSDB authorized to provide service where the
WSD is physically located to the master device. If spectrum access
is not authorized at the WSD physical location, the response will
contain an error code and no address information.
After WSDB discovery procedure, the master device can query available
white space spectrum from the WSDB using PAWS protocol.
3.1. System Architecture
The discovery system is based on client-server model; the basic model
is shown as Figure 3, where WSDB DB plays the role of server.
+----------+ +----------+
| Master | <--------> | WSDB DS |
+----------+ +----------+
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Figure 3: DB discovery system model
For the discovery mechanism to work well, some assumptions have to be
considered:
(1) Master device can get its geo-location directly or indirectly.
(2) Master device has gotten the URL (or IP address) of a trusted
WSDB DS before starting the discovery procedure.
By including contact information of a trusted WSDB DS in the WSD's
programmed instructions or firmware, the WSD can reliably determine
the address of a trusted database listing server, as appropriate for
its current physical location. Because the WSDB DS is selected by
the WSD manufacturer, a foundation is set to ensure the WSD will be
able to discover a trusted WSDB in every regulatory domain where the
manufacturer expects the WSD to be used. The address of at least one
WSDB DS is included in the WSD operating instructions or firmware by
the manufacturer for example or provisioned using device
configuration mechanisms.
When the WSD does not have the address of a serviceable WSDB (e.g. at
power-up), the WSD sends a Discovery Request message to a WSDB DS.
The WSD includes in the Discovery Request information about its
current location. The WSDB DS uses this location information to
determine the regulatory domain where the WSD is located, and returns
a Discovery Response message which includes the address of one or
more WSDBs (or WSDB listing server as appropriate) to the WSD.
4. Specification
LoST (Location to Service Translation Protocol) is a protocol for
mapping a service identifier (URN) and location information to one or
more service URLs and associated information. LoST mapping queries
can contain either civic or geodetic location information. LoST
queries can be resolved recursively or iteratively.
LoST messages are carried in HTTP and HTTPS protocol exchanges,
facilitating use of TLS for protecting the integrity and
confidentiality of requests and responses.
This discovery mechanism utilizes LoST to communicate between master
device and WSDB DS, the master device acts as LoST client and WSDB DS
plays the role of LoST server. The protocol stack is shown in Figure
4. To use LoST for this discovery mechanism, several issues have to
be clarified.
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+------------+
| LoST +
+------------+
| HTTPS +
+------------+
| TCP +
+------------+
| IP +
+------------+
Figure 4: Protocol stack for discovery mechanism
4.1. Issues to be clarified
4.1.1. Service Identifier
A new service identifier for PAWS database discovery needs to be
defined, according to RFC5031 [RFC5031], a top-level service and a
sub-service are defined here.
+----------------+-------------------------------------+
| Service | Description |
+----------------+-------------------------------------+
| paws | top-level service of PAWS |
| paws.discovery | the PAWS database discovery service |
+----------------+-------------------------------------+
Table 1
So according to the service-identifying labels defined above, the
service URN for PAWS database discovery service is as follow:
urn:service:paws.discovery
4.1.2. Conveying of regulatory domain
The name of regulatory domain can be conveyed using <displayName>
element in the LoST response message.
[Note: the format and content of the regulatory domain information
are TBD.]
4.2. Discovery procedures
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4.2.1. Discovery Request procedure
The discovery request procedure uses the <findService> query message
of LoST for conveying parameters. Master device's location
information will be included in the <location> element.
The service identifier defined in section 5.1.1 is specified in the
<service>element.
The following is an example of discovery request procedure message,
using geodetic coordinates.
<?xml version="1.0" encoding="UTF-8"?>
<findService
xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:p2="http://www.opengis.net/gml"
serviceBoundary="value"
recursive="true">
<location id="6020688f1ce1896d" profile="geodetic-2d">
<p2:Point id="point1" srsName="urn:ogc:def:crs:EPSG::4326">
<p2:pos>37.775 -122.422</p2:pos>
</p2:Point>
</location>
<service>urn:service:paws.discovery</service>
</findService>
4.2.2. Discovery Response procedure
The discovery response procedure uses the <findServiceResponse>
response message of LoST for conveying parameters.
After receiving the <findService> query message, the WSDB DS will map
the location information and service identifier to one or more
available WSDBs' URL.
Then in the <findServiceResponse> message, a list of WSDBs' URL and
regulatory domain that has jurisdiction over the current location
will be conveyed to master device. The regulatory domain is
contained in <displayName> element.
The service boundary of the WSDB can also be included in the response
message to indicate the region for which the service URL returned
would be the same as in the actual query. Or a service boundary
reference can be returned to master device, and master device
retrieve service boundary by this reference as needed. Next time
when the master device powers up, if its location is within the
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service boundary it then may use the WSDB retrieved before.
An example of discovery response procedure message is shown as
follow:
<?xml version="1.0" encoding="UTF-8"?>
<findServiceResponse xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:p2="http://www.opengis.net/gml">
<mapping
expires="2013-05-01T01:44:33Z"
lastUpdated="2012-11-01T01:00:00Z"
source="authoritative.example"
sourceId="7e3f40b098c711dbb6060800200c9a66">
<displayName xml:lang="en">
Federal Communications Commission
</displayName>
<service>urn:service:paws.discovery</service>
<serviceBoundary profile="geodetic-2d">
<p2:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
<p2:exterior>
<p2:LinearRing>
<p2:pos>37.775 -122.4194</p2:pos>
<p2:pos>37.555 -122.4194</p2:pos>
<p2:pos>37.555 -122.4264</p2:pos>
<p2:pos>37.775 -122.4264</p2:pos>
<p2:pos>37.775 -122.4194</p2:pos>
</p2:LinearRing>
</p2:exterior>
</p2:Polygon>
</serviceBoundary>
<uri>database1.example1.com</uri>
<uri>database2.example2.com</uri>
</mapping>
<path>
<via source="resolver.example"/>
<via source="authoritative.example"/>
</path>
<locationUsed id="6020688f1ce1896d"/>
</findServiceResponse>
4.2.3. Recursion and Iteration
If the WSDB DS can not provide available WSDB for master device, then
it may wish other WSDB DS to serve the master device's query request.
In LoST, recursion and iteration patterns are provided for this
purpose.
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In recursive mode, the LoST server initiates queries on behalf of the
requester and returns the result to the requester.
In iterative mode, the server contacted returns a redirection
response indicating the next server to be queried if the server
contacted cannot provide an answer itself.
5. Security Considerations
TBD.
6. IANA Consideration
Registration of service URN for PAWS database discovery service.
+----------------+-------------------------------------+
| Service | Description |
+----------------+-------------------------------------+
| paws | top-level service of PAWS |
| paws.discovery | the PAWS database discovery service |
+----------------+-------------------------------------+
Table 2
7. Acknowledgements
Thanks to my colleagues for their sincerely help and comments when
drafting 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.
[RFC5031] Schulzrinne, H., "A Uniform Resource Name (URN) for
Emergency and Other Well-Known Services", RFC 5031,
January 2008.
[RFC5222] Hardie, T., Newton, A., Schulzrinne, H., and H.
Tschofenig, "LoST: A Location-to-Service Translation
Protocol", RFC 5222, August 2008.
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8.2. Informative References
[PAWS PROTOCOL]
Chen, V., Das, S., Zhu, L., McCann, P., and J. Malyar,
"Protocol to Access Spectrum Database",
draft-ietf-paws-protocol-01 (work in progress),
December 2012.
[PAWS RQMTS]
Probasco, S. and B. Patil, "Protocol to Access White Space
database: PS, use cases and rqmts",
draft-ietf-paws-problem-stmt-usecases-rqmts-12 (work in
progress), January 2013.
Authors' Addresses
Xinpeng Wei
Huawei
Phone: +86 134 3682 2355
Email: weixinpeng@huawei.com
Lei Zhu
Huawei
Phone: +86 139 1015 7020
Email: lei.zhu@huawei.com
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