PAWS Lei. Zhu
Internet-Draft Huawei Technologies
Intended status: Informational July 25, 2011
Expires: January 26, 2012
Protocol to Access White Space database: Use cases and requirements
draft-lei-paws-overview-usecases-00.txt
Abstract
Wireless spectrum is a commodity that is regulated by governments.
The spectrum is used for various purposes which include entertainment
(eg. radio and television), communication (telephony and Internet
access), military (radars etc.) and, navigation (satellite
communication, GPS). Portions of the radio spectrum that are unused
or unoccupied at specific locations and times are defined as "white
space". TV White space refers to those unused channels, within the
range allocated for TV transmission, that can be used without
interfering with the primary purpose for which it is allocated.
This document describes examples of how a radio system might operate
using TV white space spectrum and associated requirements. Not only
does it describe the operation of a radio system, but also how the
radio system including a white space database enables additional
services.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 26, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
Zhu Expires January 26, 2012 [Page 1]
Internet-Draft PAWS:Use cases July 2011
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.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Zhu Expires January 26, 2012 [Page 2]
Internet-Draft PAWS:Use cases July 2011
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 5
2.1. Conventions Used in This Document . . . . . . . . . . . . 5
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Indoor usage of TVWS . . . . . . . . . . . . . . . . . . . 5
3.2. TVWS based ad-hoc network . . . . . . . . . . . . . . . . 6
3.3. TVWS based TD-LTE MBMS . . . . . . . . . . . . . . . . . . 8
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1. Master . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2. Database . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Security . . . . . . . . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
9. Normative Reference . . . . . . . . . . . . . . . . . . . . . 12
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12
Zhu Expires January 26, 2012 [Page 3]
Internet-Draft PAWS:Use cases July 2011
1. Introduction
Wireless spectrum is a commodity that is regulated by governments.
The spectrum is used for various purposes which include entertainment
(eg. radio and television), communication (telephony and Internet
access), military (radars etc.) and, navigation (satellite
communication, GPS). Additionally spectrum is allocated for use
either on a license basis or for unlicensed use. Television
transmission until now has primarily been analog. The switch to
digital transmission has begun. As a result the spectrum allocated
for television transmission can now be more effectively used. Unused
channels and bands between channels can be used as long as they do
not interfere with the primary service for which that channel is
allocated. While urban areas tend to have dense usage of spectrum
and a number of TV channels, the same is not true in rural and semi-
urban areas. There can be a number of unused TV channels in such
areas that can be used for other services. The figure below shows TV
white space within the lower UHF band:
Avg |
usage| |------------ White Space
| | | | | |
0.6| || || V V ||
| || ||| | ||
0.4| || |||| | ||
| || |||| | ||<--TV transmission
0.2| || |||| | ||
|----------------------------------------
400 500 600 700 800
Frequency in MHz ->
Figure 1: High level view of TV White Space
Regulatory entities in several countries including the US, Canada,
UK, Finland to name a few are specifying the regulations for the use
of TV white space. The availability of TV white space opens up the
potential for its use for various purposes. Regulation may mandate
its use for certain specific applications or services.
This document describes an example of how a radio system might
operate using TV white space spectrum. Not only does it describe the
operation of a radio system for providing Internet access at a hot
spot or in a rural area, but also how the radio system including a
white space database enables location based services. The
description is high level and generic, it is not meant to be specific
to any particular radio technology.
Zhu Expires January 26, 2012 [Page 4]
Internet-Draft PAWS:Use cases July 2011
2. Conventions and Terminology
2.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.2. Terminology
The Terminology Section of the latest version of
draft-patil-paws-problem-stmt [PAWS-PS] shall be included by
reference.
Master Device
A device which queries the WS Database to find out the available
operating channels.
Slave Device
A device which uses the spectrum made available by a master
device.
3. Use cases
There are many potential use cases that could be considered for the
TV white space spectrum. Providing broadband internet access in hot
spots, rural and underserved areas are examples. Available channels
may also be used to provide internet 'backhaul' for traditional Wi-Fi
hot spots, or by towns and cities to monitor/control traffic lights
or read utility meters. Still other use cases include the ability to
offload data traffic from another internet access network (e.g. 3G
cellular network) or to deliver location based services. Some of
these use cases are described in the following sections.
3.1. Indoor usage of TVWS
At present, the indoor wireless coverage devices consist of Wi-Fi-
like access points and micro cells, all of these utilize single
segment of frequency, former at about 2.4GHz and the latter, for
example, TD-LTE, at about 2.1GHz. Due to the block of buildings and
other obstruction and interfere, it may not be that optimistic when
we consider the wireless receiving. This use case takes the benefit
of the excellent propagation performance of a radio network operating
in TV White Space frequency bands i.e. 470-790 MHz to increase
Zhu Expires January 26, 2012 [Page 5]
Internet-Draft PAWS:Use cases July 2011
capacity and reduce same or unique frequency interfere coming from
the macro cell.
The figure below shows an example deployment of this scenario.
+--------------------------------+
| indoor |
| |
+--------------------------------+
| |
| +------+ white space | +-------------+
| |iphone| - - - - - - - - - -|- -| Micro cell |
| +------+ \ | +-------------+
| +------+ \white space | (-----)
| | ipad | \ +------------+| / \
| +------+ |access point||===( Internet)
| o / +------------+| \ /
| o / | (-----)
| o / |
| |
+--------------------------------+
Graph 1 Indoor usage of TVWS
The access point could be a WI-FI deviceGBP[not]and the micro cell is
short range wireless coverage(e.g. in range of 0-50m) base station,
both of them act as role of master device, query the internet
connected database for available white space spectrum based on its
geo-location, and provide TVWS access to user terminals indoor. It's
beyond our consideration in this draft when and how to switch between
legally licensed TD-LTE frequency and available TVWS.
The TVWS frequency spectrum has different propagation characteristics
compared to higher frequency band, for instance, the propagation
distance using TVWS may be several times longer than those in the
higher range. In this case, good penetration characteristic makes it
difficult to lock the signal in the room, then difficult to localize
and differentiate signals, and finally cause interferes among
neighbor networks. Suggestion to ease such headache would be:
relative higher WS frequency; a frequency protection gap between
neighbors; lower power output of AP/micro cell, it seems that only
certain pico or femto cells be feasible here.
3.2. TVWS based ad-hoc network
When establishing an ad-hoc network, one node act as the primary
device in charge of connection management, we can call it a virtual
Zhu Expires January 26, 2012 [Page 6]
Internet-Draft PAWS:Use cases July 2011
AP; other devices act as slave devices and connect themselves to this
virtual AP, thus forming P2P ad-hoc network. It provides us an
informal but convenient way to share information with each other, and
expand the wireless coverage by accepting one new device join in the
ad-hoc network. However, the coverage of a wireless device for
example, WI-FI, in the room environment, normally shorter than 50m,
so reliable wireless communication may not be available when device
distance beyond this limit. Introducing TVWS to ad-hoc network bring
in at least two benefits: wider coverage owing to good propagation
characteristics of TVWS; release frequencies previously occupied by
ad-hoc and reduce interfere.
The figure below shows an example deployment of this scenario.
\|/
| +----------+
+-|-------+ | Database |
|Device 2 | +----------+
+---------+ \ \
\|/ \ \|/ \ .----.
| \ | ( )
+-|-------+ \ +-|------+ / \
|Device 3 | --- |Device 1|======( Internet )
+- -------+ +--------+ \ /
/ ( )
\|/ / .----.
| /ad-hoc via TVWS
+--|-----+ /
|Device 4|
+--------+
Graph 2 TVWS based ad-hoc network
TVWS based ad-hoc network Establishment steps:
1. Device 1 acts as the primary device and power on, other 3 devices
act as slave devices , they establish P2P connection to device 1
individually, and finally forming a regular ad-hoc network.
2. Device 1 query the database for available TVWS based on the
location and send the information to the entire ad-hoc network.
3. The 3 slave devices receive this information and start listening
on TVWS frequency.
An ad-hoc network operating on white space frequency band is
Zhu Expires January 26, 2012 [Page 7]
Internet-Draft PAWS:Use cases July 2011
available now.
The connection with the White Space geo-location database service
provider must be provided by at least one node (in this case, it is
device 1) and may use other techniques than communication over white
space frequency bands. That's to say, we could connect the device 1
to the internet with various techniques, such as wired Ethernet,
wireless connection using regular licensed TD-LTE band, even another
TVWS frequency.
Referred to mobility consideration, the spectrum usage perceived by
the network is changing, and therefore the update interval of the
spectrum usage information needs to be much higher.
3.3. TVWS based TD-LTE MBMS
When performing broadcasting services, specific radio resources need
to be reserved. With more and more kinds of broadcast applications
are introduced in, e.g., live radio/TV program broadcasting, the
radio resources may be scarce. We could turn to TVWS for help by
transmitting broadcasting services on locally available white space
frequency. In this case, TD-LTE Multimedia Broadcast Service (MBMS)
is taken into account.
The figure below shows an example deployment of this scenario.
Zhu Expires January 26, 2012 [Page 8]
Internet-Draft PAWS:Use cases July 2011
+--------+
|Service |
|platform|
.----------. +--------+
+--+ | | |
|UE| \ | +------+ | +-----+
+--+ \ .---. /| |eNodeB| | |BM-SC|
+--+ / \ / | +------+ | +-----+
|UE| ( TVWS )/ | | |
+--+ ( Based ) | +------+ | +---+
+--+ ( MBMS ) | |eNodeB| |____|MCE|
|UE| \ / \ | +------+ | +---+
+--+ /.---. \ | | |
+--+ / \| +------+ | +--------+
|UE| / | |eNodeB| | |Database|
+--+ | +------+ | +--------+
. | . |
. | . |
. | . |
| |
|MBSFN AREA|
.----------.
Graph 3 TVWS based MBMS in TD-LTE
In the upper graph, BM-SC is short for "broadcast/multicast-service
center",MCE (Multi-cell/multicast Coordination Entity) is a central
control entity which is used for admission control and allocation of
radio resource used by all the eNodeBs in the same MBSFN(Multimedia
Broadcast multicast service Single Frequency Network) area. MBSFN is
a model, in this model, a group of base stations transmit same
content with the same frequency at the same time. The base station
may be enhanced with the capability of sensing TVWS spectrums and
reporting the sensing result to the MCE.
In this case, TVWS frequency bands are only used to transmit MBMS
service data; MBMS signaling is still carried by LTE bands.
Simplified steps are as follows:
1. When BM-SC wants to start broadcast service in a MBSFN area, it
sends a message including service specified Qos parameters to MCE
which is in charge of this MBSFN area.
2. MCE is aware of load condition of the whole MBSFN area, so, if
the radio resources are not sufficient in this area to meet the
Zhu Expires January 26, 2012 [Page 9]
Internet-Draft PAWS:Use cases July 2011
Qos requirements, MCE query the database to get the information
of TVWS spectrum usage status and decides whether suitable TVWS
frequency bands are available for transmitting broadcasting
service in this area.
3. If there exists no available TVWS frequency bands in this MBSFN
area, MCE would inform BM-SC that broadcast service is rejected;
else, MCE would send a configuration command which includes
allocated TVWS to all the eNodeBs in this area.
4. eNodeBs configure themselves and send configuration response
command to MCE; then eNodeBs broadcast a message including
allocated TVWS to UEs so as to inform them preparing to receive
broadcast service on TVWS.
4. Requirements
4.1. Master
1. A master device MUST include, directly or indirectly, its antenna
height in the query to the WS Database.
2. A master device MUST query the WS Database for the available
channels at least once a day to verify that the operating
channels continue to remain available.
3. A master device MUST determine its location with at least =/-50
meters accuracy and MUST place that location into the query it
makes to the WS Database.
4. A master device MAY indicate the accuracy by which it determined
its location in the query to the WS Database.
5. A master device which changes its location during operation MUST
query the WS Database for available operating channels each time
it moves more than 100 meters from the location it previously
made the query.
6. A master device MUST be able to receive channel availability
updates from a WS Database.
7. A master device MUST be able to query the WS Database for channel
availability information for multiple locations.
8. A master device MUST be able to query the WS Database for channel
availability information for a specific area around its current
location.
Zhu Expires January 26, 2012 [Page 10]
Internet-Draft PAWS:Use cases July 2011
9. A master device MUST query the WS Database and include the FCC ID
of the slave device in the query before allowing the slave device
to use the available channel.
4.2. Database
1. The WS Database MUST provide the available channel list when
requested and MAY also provide time constraints for the channel
list and maximum output power to the master device.
4.3. Security
1. The protocol between the master device and the WS Database MUST
support mutual authentication and authorization.
2. The protocol between the master device and the WS Database MUST
support integrity and confidentiality protection.
3. The WS Database MUST support both username/password and digital
certificates based authentication of the master device.
4. A master device MUST be capable to validate the digital
certificate of the WS Database.
5. A master device MUST be capable to check the validity of the WS
Database certificate and whether it has been revoked or not.
5. IANA Considerations
There have been no IANA considerations so far in this document.
6. Security Considerations
The messaging interface between the master and the database must be
secure to ensure confidentiality, authenticity and integrity of the
data exchanged between devices. A master queries a database with
information which identifies owner/operator of the device and also
the location of the device. Such information can reasonably
considered to be sensitive information which must remain
confidential. A well-functioning white space network relies upon
trusted devices exchanging trusted information, thus each participant
in the protocol exchange must be authenticated. A white space
network must ensure the protection of the primary user of the radio
spectrum, therefore the integrity of the message exchange must be
ensured.
Zhu Expires January 26, 2012 [Page 11]
Internet-Draft PAWS:Use cases July 2011
7. Summary and Conclusion
The document describes some examples of the role of the white space
database in the operation of a radio network and also shows an
examples of a services provided to the user of a TVWS device. From
these use cases requirements are determined. These requirements are
to be used as input to the definition of a Protocol to Access White
Space database (PAWS).
8. Acknowledgments
Thanks to my colleagues for their sincerely help and comments which
helped in forming this draft.
9. Normative Reference
[I-D.patil-paws-problem-stmt]
Patil, B., Probasco, S., and G. Bajko, "Protocol to Access
White Space database: Problem statement and Requirements",
draft-patil-paws-problem-stmt-00 (work in progress),
February 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Author's Address
Lei Zhu
Huawei Technologies
Huawei Building, No.156 Beiqing Rd.Z-park
Haidian District, Beijing 100085
P. R. China
Phone: +86-10-60612078
Email: lei.zhu@huawei.com
Zhu Expires January 26, 2012 [Page 12]