Scott Sorry, there is an error in my own correction... it should read "2011 Ofcom Statement" not 2009.
Regards Andy -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: 30 January 2012 16:56 To: [email protected]; [email protected] Subject: Re: [paws] Use cases and requirements I-D: sections 1 to 3 (Introduction, Conventions and Terminology, Prior Work) Scott [Ofcom Implementing] appears in the references section but not the main text. I propose to reference it from the end of one sentence in the second paragraph, and slightly amend the wording. The changed text would be: Ofcom published in 2004 their Spectrum Framework Review [Spectrum Framework Review] and their Digital Dividend Review [DDR] in 2005, with proposals from 2009 onwards to access TV white space, culminating in the 2009 Ofcom Statement Implementing Geolocation [Ofcom Implementing]. Regards Andy -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: 25 January 2012 20:49 To: [email protected] Subject: [paws] Use cases and requirements I-D: sections 1 to 3 (Introduction, Conventions and Terminology, Prior Work) Hello All, As editors of the problem statement, use cases & requirements draft we are attempting to prepare a completed draft which could be ready for working group last call before IETF83. In the coming days we will post the sections of the draft to the mailing list. Our request is that you review these sections and reply to the email with any comments. Below is the text for sections 1 to 3. This text has not changed from version-01 as uploaded October 31, 2011. Our goal is that any discussion on this text will conclude by February 1. To be clear, approval of the document will go through the normal process of last calls etc.. We are simply asking for your assistance in preparing a complete & accurate document that could progress the work. So please review the text and send your comments either directly to the editor or to the mailing list. Kind Regards, Raj & Scott 1. Introduction 1.1. Introduction to TV white space Wireless spectrum is a commodity that is regulated by governments. The spectrum is used for various purposes, which include entertainment (e.g. radio and television), communication (telephony and Internet access), military (radars etc.) and, navigation (satellite communication, GPS). Portions of the radio spectrum that are allocated to a licensed, primary user but are unused or unoccupied at specific locations and times are defined as "white space". The concept of allowing secondary transmissions (licensed or unlicensed) 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 primary 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 allocated to them. The available spectrum for a secondary use 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 primary spectrum is available for secondary use. Academia and Industry have studied multiple cognitive radio mechanisms for use in such a scenario. One simple mechanism is to use a geospatial database that records the primary users occupation, and require the secondary users to check the database prior to selecting what part of the spectrum they use. Such databases could be available on the Internet for query by secondary users. Spectrum useable for data communications, especially wireless Internet communications, is scarce. 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 a given area. In 2008 the United States regulator (the FCC) took initial steps when they published their first ruling on the use of TV white space, and then followed it 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. More countries are expected to provide access to their TV spectrum in similar ways. Any entity holding spectrum that is not densely used may be asked to give it up in one way or another for more intensive use. Providing a mechanism by which secondary users share the spectrum with the primary user is attractive in many bands in many countries. Probasco & Patil Expires July 18, 2012 [Page 4] Internet-Draft PAWS: Problem, uses and requirements January 2012 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 The fundamental issue is how to determine for a specific location and specific time if any of the spectrum is available for secondary use. There are two dimensions of use that may be interesting: space (the area in which a secondary user would not interfere with a primary user, and time: when the secondary use would not interfere with the primary use. In this discussion, we consider the time element to be relatively long term (hours in a day) rather than short term (fractions of a second). Location in this discussion is geolocation: where the transmitters (and sometimes receivers) are located relative to one another. In operation, the database records the existing user's transmitter (and some times receiver) locations along with basic transmission characteristics such as antenna height, and sometimes power. Using rules established by the regulator, the database calculates an exclusion zone for each authorized primary user, and attaches a time schedule to that use. The secondary user queries the database with its location. The database intersects the exclusion zones with the queried location, and returns the portion of the spectrum not in any exclusion zone. Such methods of geospatial database query to avoid interference have been shown to achieve favorable results, and are thus the basis for rulings by the FCC and Probasco & Patil Expires July 18, 2012 [Page 5] Internet-Draft PAWS: Problem, uses and requirements January 2012 reports from ECC and Ofcom. In any country, the rules for which primary entities are entitled to protection, how the exclusion zones are calculated, and what the limits of use by secondary entities are may vary. However, the fundamental notion of recording primary users, calculating exclusion zones, querying by location and returning available spectrum (and the schedule for that spectrum) are common This document includes the problem statement, use cases and requirements associated with the use of white space spectrum by secondary users via a database query protocol. 1.2. Scope 1.2.1. In Scope This document applies only to communications required for basic service in TV white space. The protocol will enable a white space radio device to complete the following tasks: 1. Determine the relevant white space database to query. 2. Connect to the database using a well-defined access method. 3. Register with the database using a well-defined protocol. 4. Provide its geolocation and perhaps other data to the database using a well-defined format for querying the database. 5. Receive in return a list of currently available white space using a well-defined format for returning information. As a result, some of the scenarios described in the following section are out of scope for this specification (although they might be addressed by future specifications). 1.2.2. Out of Scope The following topics are out of scope for this specification: TBD 2. Conventions and Terminology Probasco & Patil Expires July 18, 2012 [Page 6] Internet-Draft PAWS: Problem, uses and requirements January 2012 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 RFC 2119 [RFC2119]. 2.2. Terminology Database In the context of white space and cognitive radio technologies, the database is an entity which contains current information about available spectrum at any given location and other types of information. Device ID A unique number for each master device and slave device that identifies the manufacturer, model number and serial number. Location Based Service An application or device which provides data, information or service to a user based on their location. Master Device A device which queries the WS Database to find out the available operating channels. Protected Entity A primary user of white space spectrum which is afforded protection against interference by secondary users (white space devices) for its use in a given area and time. Protected Contour The exclusion area for a Protected Entity, held in the database and expressed as a polygon with geospatial points as the vertices. Slave Device A device which uses the spectrum made available by a master device. Probasco & Patil Expires July 18, 2012 [Page 7] Internet-Draft PAWS: Problem, uses and requirements January 2012 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 Radio spectrum which has been allocated for some primary use, but is not fully occupied by that primary use at a specific location and time. White Space Device (WSD) A device which is a secondary user of some part of white space spectrum. A white space device can be an access point, base station, a portable device or similar. In this context, a white space device is required to query a database with its location to obtain information about available spectrum. 3. Prior Work 3.1. 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 mechanisms including sensing (attempting to ascertain primary users by listening for them within the spectrum), location determination and internet connectivity to a database to learn the details of the local radio environment. 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. 3.2. 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]. Probasco & Patil Expires July 18, 2012 [Page 8] Internet-Draft PAWS: Problem, uses and requirements January 2012 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 referred 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. 3.3. Air Interfaces 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. _______________________________________________ paws mailing list [email protected] https://www.ietf.org/mailman/listinfo/paws _______________________________________________ paws mailing list [email protected] https://www.ietf.org/mailman/listinfo/paws _______________________________________________ paws mailing list [email protected] https://www.ietf.org/mailman/listinfo/paws
