Individual Submission B. Patil, Ed. Internet-Draft Intended status: Informational S. Probasco Expires: August 26, 2011 G. Bajko Nokia February 22, 2011 Protocol to Access White Space database: Problem statement and Requirements draft-patil-paws-problem-stmt-00 Abstract Governments around the world continue to search for new pieces of radio spectrum which can be used by the expanding wireless communications industry to provide Broadband Wireless Access (BWA). The concept of allowing secondary or unlicensed transmissions in frequencies occupied by a primary or licensed user is a technique to "unlock" existing spectrum for new use. An obvious requirement is that these secondary or unlicensed transmissions do not interfere with the primary or licensed use of the spectrum. The fundamental issue is how to determine for a specific location and specific time if any TV channels are available for unlicensed use, e.g. they are not being used for TV broadcast or by a wireless microphone. Academia and Industry have studied multiple cognitive radio enablers for use in such a scenario. The methods of geolocation and database have been shown to achieve favorable results. This document discusses the requirements and the problems that need to be addressed for enabling the use of white-space spectrum by obtaining information from a database. 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 August 26, 2011. Patil, et al. Expires August 26, 2011 [Page 1] Internet-Draft PAWS: PS and Reqmts February 2011 Copyright Notice Copyright (c) 2011 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 2. Terminology and Concepts . . . . . . . . . . . . . . . . . . . 4 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. The concept of Cognitive Radio . . . . . . . . . . . . . . 5 3. Background information on white space in US . . . . . . . . . 5 4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Global applicability . . . . . . . . . . . . . . . . . . . 7 4.2. Database discovery . . . . . . . . . . . . . . . . . . . . 7 4.3. Data model definition . . . . . . . . . . . . . . . . . . 8 4.4. Security requirements . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 9. Informative References . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Patil, et al. Expires August 26, 2011 [Page 2] Internet-Draft PAWS: PS and Reqmts February 2011 1. Introduction Governments around the world continue to search for new pieces of radio spectrum which can be used by the expanding wireless communications industry to provide Broadband Wireless Access (BWA). One area which has received much attention globally is the TV white space: portions of the TV band that are not used by broadcasters. In 2008 the FCC took beginning steps when they published their first ruling on use of TV white space, and then followed up with a final ruling in 2010[FCC ruling]. Finland passed an Act in 2009 enabling testing of cognitive radio systems in the TV white space. The ECC has completed Report 159 [ECC Report 159] containing requirements for operation of cognitive radio systems in the TV white space. Ofcom published in 2004 their Spectrum Framework Review [Spectrum Framework Review] and their Digital Dividend Review [DDR] in 2005, and have followed up with a proposal to access TV white space. The concept of allowing secondary or unlicensed transmissions in frequencies occupied by a primary or licensed user is a technique to "unlock" existing spectrum for new use. An obvious requirement is that these secondary or unlicensed transmissions do not interfere with the primary or licensed use of the spectrum. The fundamental issue is how to determine for a specific location and specific time if any TV channels are available for unlicensed use, e.g. they are not being used for TV broadcast or by a wireless microphone. Academia and Industry have studied multiple cognitive radio enablers for use in such a scenario. The methods of geolocation and database have been shown to achieve favorable results, and are thus the basis for rulings by the FCC and reports from ECC and Ofcom. However, the two cognitive radio enablers of geolocation and database are a framework, not a complete solution. There is a choice of which parameters and which algorithms to use in determining spectrum availability. The ongoing challenge is to maximize the spectrum available for unlicensed use while at the same time ensuring no interference to the licensed use of the spectrum. In a typical implementation of geolocation and database to access TV white space, a radio is configured with its location in latitude and longitude. There are multiple ways to configure this location information, e.g. programmed at installation (e.g. for a fixed device) or determined by GPS (e.g. for a or mobile device). At power-on, before the device can transmit in TV white space frequencies, the device must contact a database, provide its geolocation and receive in return a list of unoccupied or "white space" channels. The device can then select one of the channels from the list (note that it is possible they list is empty; there are no unoccupied channels at the location of the device) and then begins to transmit and receive on the selected channel. The device must query Patil, et al. Expires August 26, 2011 [Page 3] Internet-Draft PAWS: PS and Reqmts February 2011 the database again for a list of unoccupied channels based on certain conditions, e.g. a fixed amount of time has passed, the device has changed location beyond a specified threshold. The basic scenario is that before transmitting in TV white space, the device must get permission from the database. The low frequencies of the TV bands have good propagation characteristics. At these low frequencies, a radio signal will travel ~3 times further than traditional WLAN at 2.5 GHz, assuming the same transmit power. Because of these characteristics and new cognitive radio techniques, when TV white space is taken into use, this will enable new use cases and new business opportunities. Not only is the capacity of new spectrum needed, but this propagation trait by itself makes TV white space attractive for providing BWA in rural, sparsely populated areas, and also for extended range home hot-spot coverage (similar to WLAN today, but with improved coverage). In addition to propagation characteristics, the geolocation database will provide new capabilities for devices that use TV white space. When a device using TV white space registers its location in the database, this simple act makes the location of the device available for location based services. This document discusses the requirements for accessing a database to obtain information that enables a device to operate/use the available channels at a given location. It also identifies various issues that need to be addressed by the protocol between the device and database. 2. Terminology and Concepts 2.1. Terminology TV White Space TV white space refers specifically to radio spectrum which has been allocated for TV broadcast, but is not occupied by a TV broadcast, or other licensed user (such as a wireless microphone), at a specific location and time. White Space Device A white space device can be an access point, base station or a portable device. Different classes of white space devices exist. Any device which plans to use the available spectrum to provide service/connectivity to others is required to contact a database to obtain information about available channels. Patil, et al. Expires August 26, 2011 [Page 4] Internet-Draft PAWS: PS and Reqmts February 2011 Database In the context of white space and cognitive radio technologies, the database is an entity which contains uptodate information about available spectrum at any given location, registered devices and other types of information. Cognitive Radio A cognitive radio uses knowledge of the local radio environment to dynamically adapt its own configuration and function properly in a changing radio environment. A radio which is able to dynamically which frequency to use is one example of a cognitive radio. 2.2. The concept of Cognitive Radio A cognitive radio uses knowledge of the local radio environment to dynamically adapt its own configuration and function properly in a changing radio environment. Knowledge of the local radio environment can come from various technology enablers including location determination and internet connectivity to a database to learn the details of the local radio environment. Cognitive radio technology can be used for all available portions of spectrum, even those within bands dedicated to a Primary use like TV or satellite. TV White Space is one implementation of cognitive radio. Because a cognitive radio adapts itself to the available spectrum in a manner that prevents the creation of harmful interference, the spectrum can be shared among different radio users. 3. Background information on white space in US Television transmission in the United States has moved to the use of digital signals as of June 12, 2009. Since June 13, 2009, all full- power U.S. television stations have broadcast over-the-air signals in digital only. An important benefit of the switch to all-digital broadcasting is that it freed up parts of the valuable broadcast spectrum. More information about the switch to digital transmission is at : [DTV]. With the switch to digital transmission for TV, the guard bands that existed to protect the signals between stations can now be used for other purposes. The FCC has made this spectrum available for unlicensed use and this is generally refered to as white space. Please see the details of the FCC ruling and regulations in [FCC ruling]. The spectrum can be used to provide wireless broadband as an example. The term "Super-Wifi" is also used to describe this spectrum and potential for providing wifi type of service. Patil, et al. Expires August 26, 2011 [Page 5] Internet-Draft PAWS: PS and Reqmts February 2011 Efforts are ongoing to specify air-interfaces for use in white space spectrum. IEEEs 802.11af task group is currently working on one such specification. IEEE 802.22 is another example. Other air interfaces could be specified in the future such as LTE. 4. 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/channels 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. The databases are also country specific since the available spectrum and regulations may vary. An example high-level architecture of the devices and white space databases is shown in the figure below: ----------- |WS Device| ------------ |Lat: X |\ .---. /--------|Database X| |Long: Y | \ ( ) / ------------ ----------- \-------/ \/ o ( Internet ) o ----------- /------( )\ o |WS Device| / (_____) \ ------------ |Lat: X |/ \--------|Database Y| |Long: Y | ------------ ----------- Figure 1: High level view of the White space database architecture In the figure above, note that there could be multiple databases serving white space devices. The databases are country specific since the regulations and available spectrum may vary. 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. Patil, et al. Expires August 26, 2011 [Page 6] Internet-Draft PAWS: PS and Reqmts February 2011 4.1. Global applicability The use of TV white space spectrum is currently approved by the FCC in the United States. However regulatory bodies in other countries are also considering similar use of available spectrum. The principles of cognitive radio usage for such spectrum is generally the same. Some of the regulatory details may vary on a country specific basis. But the need for devices that intend to use the spectrum to communicate with a regulatory database remains a common feature. Devices need to be able to query a database which are accessible via the Internet prior to operating in available spectrum. Information about available spectrum, channels, power, etc. are provided by the database as a response to the query from a device. The messaging interface needs to be: 1. Radio/air interface agnostic - The radio/air interface technology used by the white space device in available spectrum can be 802.11af, 802.16, 802.22, LTE etc. However the messaging interface between the white space device and the database should be agnostic to the air interface while being cognizant of the characteristics of various air-interface technologies and the need to include relevant attributes in the query to the database. 2. Globally applicable - A common messaging interface between white space devices and databases will enable the use of such spectrum for various purposes on a global basis. Devices can operate in any country where such spectrum is available and a common interface ensures uniformity in implementations and deployment. 3. Address regulatory requirements - Each country will likely have regulations that are unique to that country. The messaging interface needs to be flexible to accomodate the specific needs of a regulatory body in the country where the white space device is operating and connecting to the relevant database. 4.2. Database discovery Another aspect of the problem space is the need to discover the database. A white space device needs to find the relevant database to query based on its current location or for another location. Since the spectrum and databases are country specific, the device will need to discover the relevant database. The device needs to obtain the IP address of the specific database to which it can send queries in addition to registering itself for operation and using the available spectrum. Patil, et al. Expires August 26, 2011 [Page 7] Internet-Draft PAWS: PS and Reqmts February 2011 A database discovery mechanism needs to be specified. Reuse of existing mechanisms is an option and could be adapted for meeting the specific needs of cognitive radio technology. 4.3. Data model definition The contents of the queries and response need to be specified. A data model is required which enables the white space device to query the database while including all the relevant information such as geolocation, radio technology, power characteristics, etc. All databases are able to interpret the data model and respond to the queries using the same data model that is understood by all devices. Use of XML for specifying a data model is an option. The intent is to evaluate the best option that meets the need for use between white space devices and databases. 4.4. Security requirements The messaging interface between the white space device and the database needs to be secured. Both the queries and the responses need to be delivered securely. The messages need to be protected from eavesdropping as well as ensuring that the message content is not modfified between the end points. The queries and responses need to be integrity protected in addition to ciphering. Man-in-the-middle attacks could modify the content of a response which can cause problems for other networks or devices operating at a given location. Interference as well as total loss of service could result from malicious information being delivered to a white space device. White space devices may also be required to authenticate and register with a database prior to using it. An authentication mechanism needs to be specified for use in the context of this problem space. 5. IANA Considerations This document has no requests to IANA. 6. Security Considerations There are security aspects that need to be addressed by any solution for the problem identified in this document. This Internet draft is describing the requirements and problems that need to be addressed for a messaging interface between white space devices and databases Patil, et al. Expires August 26, 2011 [Page 8] Internet-Draft PAWS: PS and Reqmts February 2011 and does not by itself raise any security concerns. 7. Summary and Conclusion Cognitive radio and TV white space technology is now in the process of being approved by regulatory bodies around the world. In the US the FCC has already created the regulation and approved a set of database administrators. The interface between the white space devices and databases is over the Internet and uses IP connectivity. The IETF can create a common standard for use on a global basis for this interface. The IETF also has the general expertise in this area since most of the protocols used on this Interface are ones that have been developed in the IETF. In summary, this document explains the requirements and issues that need to be dealt with in specifying an interface between the white space devices and databases. The authors strongly believe that this interface specification should be undertaken in the IETF within the relevant area by creating a working group. 8. Acknowledgements The authors thank Subir Das and Tom Derryberry for their comments and input. 9. Informative References [DDR] Ofcom - Independent regulator and competition authority for the UK communications industries, "Digital Dividend Review; http://stakeholders.ofcom.org.uk/spectrum/ project-pages/ddr/". [DTV] "Digital TV Transition; http://www.dtv.gov". [ECC Report 159] Electronic Communications Committee (ECC) within the European Conference of Postal and Telecommunications Administrations (CEPT), "TECHNICAL AND OPERATIONAL REQUIREMENTS FOR THE POSSIBLE OPERATION OF COGNITIVE RADIO SYSTEMS IN THE 'WHITE SPACES' OF THE FREQUENCY BAND 470- 590 MHZ; http://www.erodocdb.dk/Docs/doc98/official/pdf/ ECCREP159.PDF", January 2011. [FCC ruling] Federal Communications Commission, "Unlicensed Operation Patil, et al. Expires August 26, 2011 [Page 9] Internet-Draft PAWS: PS and Reqmts February 2011 in the TV Broadcast Bands; http://edocket.access.gpo.gov/2010/pdf/2010-30184.pdf", December 2010. [Spectrum Framework Review] Ofcom - Independent regulator and competition authority for the UK communications industries, "Spectrum Framework Review; http://stakeholders.ofcom.org.uk/consultations/sfr/", February 2005. Authors' Addresses Basavaraj Patil (editor) 6021 Connection drive Irving, TX 75039 USA Email: basavaraj.patil@nokia.com Scott Probasco Nokia 6021 Connection drive Irving, TX 75039 USA Email: scott.probasco@nokia.com Gabor Bajko Nokia 323 Fairchild drive 6 Mountain view, CA 94043 USA Email: gabor.bajko@nokia.com Patil, et al. Expires August 26, 2011 [Page 10]