Working Group Draft S. Probasco, Ed. Internet-Draft B. Patil Intended status: Informational Nokia Expires: July 30, 2012 January 27, 2012 Protocol to Access White Space database: PS, use cases and rqmts draft-ietf-paws-problem-stmt-usecases-rqmts-02 Abstract 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 approach to using the white space spectrum at a given time and location is to verify with a database available channels. This document describes the concept of TV White Spaces. It also describes the problems that need to be addressed for enabling the use of the primary user owned white space spectrum for secondary users, without causing interference, by querying a database which knows the channel availability at any given location and time. A number of possible use cases of this spectrum and derived requirements are also described. 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 July 30, 2012. Copyright Notice Probasco & Patil Expires July 30, 2012 [Page 1] Internet-Draft PAWS: Problem, uses and requirements January 2012 Copyright (c) 2012 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. Probasco & Patil Expires July 30, 2012 [Page 2] Internet-Draft PAWS: Problem, uses and requirements January 2012 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Introduction to TV white space . . . . . . . . . . . . . . 4 1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2.1. In Scope . . . . . . . . . . . . . . . . . . . . . . . 6 1.2.2. Out of Scope . . . . . . . . . . . . . . . . . . . . . 6 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 6 2.1. Conventions Used in This Document . . . . . . . . . . . . 7 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7 3. Prior Work . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.1. The concept of Cognitive Radio . . . . . . . . . . . . . . 8 3.2. Background information on white space in US . . . . . . . 8 3.3. Air Interfaces . . . . . . . . . . . . . . . . . . . . . . 9 4. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1. TVWS database discovery . . . . . . . . . . . . . . . . . 9 4.2. Device registration with trusted Database . . . . . . . . 10 4.3. Hotspot: urban internet connectivity service . . . . . . . 11 4.4. Wide-Area or Rural internet broadband access . . . . . . . 13 4.5. Offloading: moving traffic to a white space network . . . 15 4.6. TVWS for backhaul . . . . . . . . . . . . . . . . . . . . 17 4.7. Rapid deployed network for emergency scenario . . . . . . 18 4.8. Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.9. Indoor Networking . . . . . . . . . . . . . . . . . . . . 21 4.10. Machine to Machine (M2M) . . . . . . . . . . . . . . . . . 23 5. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 24 5.1. Global applicability . . . . . . . . . . . . . . . . . . . 25 5.2. Database discovery . . . . . . . . . . . . . . . . . . . . 26 5.3. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 27 5.4. Data model definition . . . . . . . . . . . . . . . . . . 27 6. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 27 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 8. Security Considerations . . . . . . . . . . . . . . . . . . . 30 9. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 31 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 31 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32 11.1. Normative References . . . . . . . . . . . . . . . . . . . 32 11.2. Informative References . . . . . . . . . . . . . . . . . . 32 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33 Probasco & Patil Expires July 30, 2012 [Page 3] Internet-Draft PAWS: Problem, uses and requirements January 2012 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 30, 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 30, 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 30, 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 30, 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 30, 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. 4. Use cases There are many potential use cases that could be considered for the TV white space spectrum. Providing broadband internet access in hotspots, rural and underserved areas are examples. Available channels may also be used to provide internet 'backhaul' for traditional Wi-Fi hotspots, 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. 4.1. TVWS database discovery This use case is preliminary to creating a radio network using TV white space; it is a prerequisite to other use cases. The radio network is created by a master device. Before the master device can transmit in TV white space spectrum, it must contact a trusted database where the device can learn if any channels are available for it to use. The master device will need to discover a trusted database in the relvant regulatory domain, using the following steps: 1. The master device is connected to the internet by any means other than using the TV white space radio. 2. The master device constructs and sends a service request over the Internet to discover availability of trusted databases in the local domain and waits for responses. Probasco & Patil Expires July 30, 2012 [Page 9] Internet-Draft PAWS: Problem, uses and requirements January 2012 3. If no acceptable response is received within a pre-configured time limit, the master device concludes that no trusted database is available. If at least one response is received, the master device evaluates the response(s) to determine if a trusted database can be identified where the master device is able to register and receive service from the database. Optionally the radio device is pre-programmed with the internet address of at least one trusted database. The device can establish contact with a trusted database using one of the pre-programmed internet addresses and establish a TV white space network (as described in one of the following use cases). Optionally the initial query will be made to a listing approved by the national regulator for the domain of operation (e.g. a website either hosted by or under control of the national regulator) which maintains a list of TVWS databases and their internet addresses. The query results in the list of databases and their internet addresses being sent to the master, which then evaluates the repsonse to determine if a trusted database can be identified where the master device is able to register and receive service from the database. 4.2. Device registration with trusted Database This use case is preliminary to creating a radio network using TV white space; it is a prerequisite to other use cases. The radio network is created by a master device. Before the master device can transmit in TV white space spectrum, it must contact a trusted database where the device can learn if any channels are available for it to use. Before the database will provide information on available TV channels, the master device must register with the trusted database. Specific requirements for registration come from individual regulatory domains and may be different. The figure below shows an example deployment of this scenario. Probasco & Patil Expires July 30, 2012 [Page 10] Internet-Draft PAWS: Problem, uses and requirements January 2012 \|/ ---------- | |Database| | .---. /--------- |-|---------| ( ) / \|/ | Master | / \ | / | |========( Internet ) | / |-----------| \ / +-|----+ (TDD AirIF) ( ) |Master| / (----) | | / +------+ Figure 2: Example illustration of registration requirement in TV white space use-case A simplified operational scenario showing registration consists of the following steps: 1. The master device must register with the most current and up-to- date information. Typically the master device will register prior to operating in TV white space for the first time after power up, after changing location by a predetermined distance, and after regular time intervals. 2. The master device shall provide to the database during registration a minimum of the Device ID, serial number assigned by the manufacturer and the device's location. 3. Depending upon regulatory domain requirements, the device may also provide device antenna height above ground, name of the individual or business that owns the device, name of a contact person responsible for the device's operation, address for the contact person, email address for the contact person and phone number of the contact person to the database during registration. 4.3. Hotspot: urban internet connectivity service In this use case internet connectivity service is provided in a "hotspot" to local users. Typical deployment scenarios include urban areas where internet connectivity is provided to local businesses and residents, and campus environments where internet connectivity is provided to local buildings and relatively small outdoor areas. This deployment scenario is typically characterized by multiple masters (APs or hotspots) in close proximity, with low antenna height, cells with relatively small radius (a few kilometers or less), and limited numbers of available radio channels. Many of the masters/APs are assumed to be individually deployed and operated, i.e. there is no coordination between many of the masters/APs. The masters/APs in Probasco & Patil Expires July 30, 2012 [Page 11] Internet-Draft PAWS: Problem, uses and requirements January 2012 this scenario use a TDD radio technology and transmit at or below a relatively low transmit power threshold. Each master/AP has a connection to the internet and provides internet connectivity to multiple master and or slave devices. The figure below shows an example deployment of this scenario. -------- |Device|\ \|/ ---------- | 1 | (TDD AirIF) | |Database| -------- \ | .---. /--------- o \ |-|---------| ( ) / o | Master | / \ o / | |========( Internet ) o / |-----------| \ / -------- (TDD AirIF) ( ) |Device| / (----) | n | -------- Figure 3: Hotspot service using TV white space spectrum Once a master/AP has been correctly installed and configured, a simplified power up and operation scenario utilizing TV White Space to provide Internet connectivity service consists of the following steps: 1. The master/AP powers up; however its WS radio and all other WS capable devices will power up in idle/listen only mode (no active transmissions on the WS frequency band). 2. The master/AP has Internet connectivity and establishes a connection to a trusted white space database (see Section 4.1). 3. The master/AP registers with the trusted database according to regulatory domain requirements (see Section 4.2). 4. Following the registration process, the master/AP will send a query to the trusted database requesting a list of available WS channels based upon its geolocation. 5. If the master/AP has met all regulatory domain requirements (e.g. been previously authenticated, etc), the database responds with a list of available white space channels that the master may use, and optionally a duration of time for their use. Probasco & Patil Expires July 30, 2012 [Page 12] Internet-Draft PAWS: Problem, uses and requirements January 2012 6. Once the master/AP has met all regulatory domain requirements (e.g. authenticated the WS channel list response message from the database, etc), the AP selects an available WS channel(s) from the list. 7. The slave or user device scans the TV bands to locate a master/AP transmission, and associates with the AP. The slave/user device queries the master for a channel list, providing to the master the slaves' Device ID and geolocation. 8. Once the master/AP has met all regulatory domain requirements (e.g. validating the Device ID with the trusted database, etc) the master provides the list of channels locally available to the slave/user device. If the channel that the user terminal is currently using is not included in the list of locally available channels, the slave/user device ceases all operation on its current channel. The slave/user device may scan for another AP transmission on a different channel. 4.4. Wide-Area or Rural internet broadband access In this use case, internet broadband access is provided as a Wide- Area Network (WAN) or Wireless Regional Area Network (WRAN). A typical deployment scenario is a wide area or rural area, where internet broadband access is provided to local businesses and residents from a master (i.e. BS) connected to the internet. This deployment scenario is typically characterized by one or more fixed master(s)/BS(s), cells with relatively large radius (tens of kilometers, up to 100 km), and a number of available radio channels. Some of the masters/BSs may be deployed and operated by a single entity, i.e. there can be centralized coordination between these masters/BSs, whereas other masters/BSs may be deployed and operated by operators competing for the radio channels in a license-exempt TVWS environment where decentralized coordination using the air- interface would be required. The BS in this scenario use a TDD radio technology and transmit at or below a transmit power limit established by the local regulator. Each base station has a connection to the internet and provides internet connectivity to multiple slave/end-user devices. End user terminals or devices may be fixed or portable. The figure below shows an example deployment of this scenario. Probasco & Patil Expires July 30, 2012 [Page 13] Internet-Draft PAWS: Problem, uses and requirements January 2012 ------- |Slave|\ \|/ ---------- |Dev 1| (TDD AirIF) | |Database| ------- \ | .---. /---------- o \ |-|---------| ( ) / o | Master | / \ o / | (BS) |========( Internet ) o / |-----------| \ / ------- (TDD AirIF) ( ) |Slave| / (----) |Dev n| ------- Figure 4: Rural internet broadband access using TV white space spectrum Once the master/BS has been professionally installed and configured, a simplified power up and operation scenario utilizing TV White Space to provide rural internet broadband access consists of the following steps: 1. The master/BS powers up; however its WS radio and all other WS capable devices will power up in idle/listen only mode (No active transmissions on the WS frequency band) 2. The master/BS has internet connectivity and establishes a connection to a trusted white space database (see use case "TVWS database discovery" above). 3. The master/BS registers its geolocation, address, contact information, etc. associated with the owner/operator of the master/BS with the trusted database service (if not currently registered, see Section 4.2). Meanwhile the DB administrator may be required to store and forward the registration information to the regulatory authority. If a trusted white space database administrator is not discovered, further operation of the WRAN may be allowed according to local regulator policy (in this case operation of the WRAN is outside the scope of the PAWS protocol). 4. Following the registration process, the master/BS will send a query to the trusted database requesting a list of available WS channels based upon its geolocation. 5. If the master/BS has been previously authenticated, the database responds with a list of available white space channels that may be used and optionally a maximum transmit power (EIRP) for each channel and a duration of time the channel may be used. Probasco & Patil Expires July 30, 2012 [Page 14] Internet-Draft PAWS: Problem, uses and requirements January 2012 6. Once the master/BS authenticates the WS channel list response message from the database, the master/BS selects an available WS channel(s) from the list. The operator may disallow some channels from the list to suit local needs if required. 7. The slave or user device scans the TV bands to locate a WRAN transmission, and associates with the master/BS. The slave/user device provides its geolocation to the BS which, in turn, queries the database for a list of channels available at the slaves' geolocation. 8. Once this list of available channels is received from the database by the master, the latter will decide, based on the list of available channels for all its other associated slaves whether it should continue operation on its current channel or change channel to accommodate the new slave in case this channel is not available at its location. The master will notify all its associated slaves/user devices of the new channel to move to if operation needs to change channel. If the channel that the user terminal is currently using is not included in the list of locally available channels, the master will drop its association with the slave/user device so that it ceases all operation on its current channel and indicate the new operating channel before dropping the link if a change has been decided. The slave/user device may move to the indicated new channel if so indicated or scan for another WRAN transmission on a different channel. 4.5. Offloading: moving traffic to a white space network In this use case internet connectivity service is provided over TV white space as a supplemental or alternative datapath to a 3G or other internet connection. In a typical deployment scenario an end user has a primary internet connection such as a 3G cellular packet data subscription. The user wants to use a widget or application to stream video from an online service (e.g. youtube) to their device. Before the widget starts the streaming connection it checks connectivity options available at the current time and location. Both 3G cellular data is available as well as TVWS connectivity (the user is within coverage of a TVWS master -- hotspot, WAN, WRAN or similar). The user may decide for many and various reasons such as cost, RF coverage, data caps, etc. to prefer the TVWS connection over the 3G cellular data connection. Either by user selection, preconfigured preferences, or other algorithm, the streaming session is started over the TVWS internet connection instead of the 3G cellular connection. This deployment scenario is typically characterized by a TVWS master/AP providing local coverage in the same geographical area as a 3G cellular system. The master/AP is assumed to be individually deployed and operated, i.e. the master/AP Probasco & Patil Expires July 30, 2012 [Page 15] Internet-Draft PAWS: Problem, uses and requirements January 2012 is deployed and operated by the user at his home or perhaps by a small business such as a coffee shop. The master/AP has a connection to the internet and provides internet connectivity to the slave/ end-user's device. The figure below shows an example deployment of this scenario. \|/ | | |-|---------| | Master/AP |\ /| Router | \ Streaming/ |-----------| \ -------- / \ ----------- |Slave/| / \ (----) | Database | |WS Dev| \ ( ) /---------- ------- \ \ / \ \ X( Internet ) \ / \ / Signaling \|/ / ( )\ \ | / (----) \---------- \ | / | YouTube | \|-|---------| / ---------- | | / | 3G BTS |/ |-----------| Figure 5: Offloading: moving traffic to a white space network Once a dual or multi mode device (3G + TVWS) is connected to a 3G network, a simplified operation scenario of offloading selected content such as video stream from the 3G connection to the TWVS connection consists of the following steps: 1. The dual mode (or multi mode) device (3G + TVWS) is connected to a 3G network. The device has contacted a trusted database to discover the list of available TV channels at its current location. The device has located a TVWS master/AP operating on an available channel and has associated or connected with the TVWS master/AP. 2. The user activates a widget or application that streams video from YouTube. The widget connects to YouTube over 3G cellular data. The user browses content and searches for video selections. Probasco & Patil Expires July 30, 2012 [Page 16] Internet-Draft PAWS: Problem, uses and requirements January 2012 3. The user selects a video for streaming using the widget's controls. Before the widget initiates a streaming session, the widget checks the available connections in the dual mode device and finds a TVWS master/AP is connected. 4. Using either input from the user or pre-defined profile preferences, the widget selects the TVWS master/AP as the connection to stream the video. 4.6. TVWS for backhaul In this use case internet connectivity service is provided to users over a traditional wireless protocol, one common example is Wi-Fi. The TV white space network provides the "backhaul" or connection from the Wi-Fi to the internet. In a typical deployment scenario an end user has a device with a radio such as Wi-Fi. A service provider or shop owner wants to provide Wi-Fi internet service for their customers. The location where the service provider wants to provide Wi-Fi is within range of a TVWS master (e.g. Hotspot or Wide-Area/ Rural network). The service provider installs a TVWS slave device and connects this slave to a Wi-Fi access point. This deployment scenario is typically characterized by a TVWS master/AP/BS providing local coverage. The master/AP has a connection to the internet and provides internet connectivity to the slave device. The slave device is then 'bridged' to a Wi-Fi network The figure below shows an example deployment of this scenario. \|/ white \|/ \|/ WiFi \|/ | space | | | | | | |-|----| |--------| |-|---------| |-|------|-| | WiFi | | | | Master | | Slave | | Dev | |internet|------| (AP/BS) | | Bridge | |------| | | | | | to WiFi | |--------| |-----------| |----------| \|/ | |-|----| | WiFi | | Dev | |------| Figure 6: TVWS for backhaul Once the bridged device (TVWS+WiFi) is connected to a master and TVWS network, a simplified operation scenario of backhaul for WiFi consists of the following steps: Probasco & Patil Expires July 30, 2012 [Page 17] Internet-Draft PAWS: Problem, uses and requirements January 2012 1. A bridged device (TVWS+WiFi) is connected to a master device operating in the TVWS. The bridged device operates as a slave device in either Hotspot or Wide-Area/Rural internet use cases described above. 2. Once the slave device is connected to the master, the Wi-Fi access point configures its internet settings automatically based on the backhaul connection (i.e. it uses DHCP). 3. End users connect their WiFi device to the bridged device and receive internet connectivity. 4.7. Rapid deployed network for emergency scenario Organizations involved in handling emergency operations often have a fully owned and controlled infrastructure, with dedicated spectrum, for day to day operation. However, lessons learned from recent disasters show such infrastructures are often highly affected by the disaster itself. To set up a replacement quickly, there is a need for fast reallocation of spectrum, where in certain cases spectrum can be freed for disaster relief. To utilize free or freed spectrum quickly and reliable, automation of allocation, assignment and configuration is needed. A preferred option is make use of a robust protocol, already adopted by radio manufacturers. This approach does in no way imply such organizations for disaster relief must compete on spectrum allocation with other white spaces users, but they can. A typical network topology would include wireless access links to the public Internet or private network, wireless ad hoc network radios working independent of a fixed infrastructure and satellite links for backup where lack of coverage, overload or outage of wireless access links occur. The figure below shows an example deployment of this scenario. Probasco & Patil Expires July 30, 2012 [Page 18] Internet-Draft PAWS: Problem, uses and requirements January 2012 \|/ | ad hoc | |-|-------------| | Master node | |------------| \|/ | with | | Whitespace | | ad hoc /| backhaul link | | Database | | /------/ |---------------| |------------| ---|------------/ | \ / | Master node | | | (--/--) | without | | ------( ) | backhaul link | | Wireless / Private \ ----------------\ | Access ( net or ) \ | \ Internet ) \ \|/ | -------( /\ \ | ad hoc | | (------) \--------- \ | | / | Other | \--|------------- /Satellite | nodes | | Master node | / Link ---------- | with |/ | backhaul link | ----------------- Figure 7: Rapid deployed network with partly connected nodes In the ad hoc network, all nodes are master nodes in a way that they allocate RF channels from the white space database. However, the backhaul link may not be available to all nodes, such as depicted for the left node in the figure. To handle RF channel allocation for such nodes, a master node with a backhaul link relays or proxies the database query for them. So master nodes without a backhaul link follow the procedure as defined for clients. The ad hoc network radios utilise the provided RF channels. Details on forming and maintenance of the ad hoc network, including repair of segmented networks caused by segments operating on different RF channels, is out of scope of spectrum allocation. 4.8. Mobility In this use case, the user has a non-fixed (portable or mobile) device and is riding in a vehicle. The user wants to have connectivity to another device which is also moving. Typical deployment scenarios include urban areas and rural areas where the user may connect to other users in peer-to-peer or ad-hoc networks. This deployment scenario is typically characterized by a master device with low antenna height, internet connectivity by some connection that does not utilize TV white space, and some means to Probasco & Patil Expires July 30, 2012 [Page 19] Internet-Draft PAWS: Problem, uses and requirements January 2012 predict its path of mobility. This knowledge of mobility could be simple (GPS plus accelerometer), sophisticated (GPS plus routing and mapping function) or completely specified by the user via user- interface. The figure below shows an example deployment of this scenario. \|/ \|/ | TDD Air Interface | | | +-|---------+ +-|---------+ | TVWS | | TVWS | |Master Dev | |Master Dev | +-----------+ +-----------+ \ (----) / \ ( ) / \ / \ / ( Internet ) \ / ( )\----------+ (----) | Database | +----------+ Figure 8: Example illustration of mobility in TV white space use-case A simplified operational scenario utilizing TV whitespace to provide peer-to-peer connectivity service in a mobility environment consists of the following steps: 1. The mobile master device powers up with its WS radio in idle or listen mode only (no active transmission on the WS frequency band). 2. The mobile master has internet connectivity and establishes a connection to a trusted white space database (see Section 4.1). 3. The mobile master registers with the trusted database according to regulatory domain requirements (see Section 4.2). 4. Following the registration process, the mobile master will send a query to the trusted database requesting a list of available WS channels based upon its current location and a prediction of its future location, extrapolated from the motion or mobility of the device. The current location is specified in latitude and longitude. The method to specify the future location is TBD, potential methods include movement vector (direction and velocity), a set of latitude/longitude points which specify a Probasco & Patil Expires July 30, 2012 [Page 20] Internet-Draft PAWS: Problem, uses and requirements January 2012 closed polygon where the future location is within the polygon, or similar. 5. If the mobile master has met all regulatory domain requirements (e.g. been previously authenticated, etc), the database responds with a list of available white space channels that the mobile master may use, and optional information which may include (1) a duration of time for the use of each channel (2) a maximum transmit power for each channel. 6. Once the mobile master has met all regulatory domain requirements (e.g. authenticated the WS channel list response message from the database, etc), the master selects an available WS channel(s) from the list for use. 7. The other user device in the peer-to-peer connection scans the TV bands to locate a mobile master transmission, and associates with the mobile master. The slave/user device queries the master for a channel list, based on the slave's device identification, geolocation and optionally a prediction of its future location. 8. If required by local regulation, the master device verifies the slave's device identification with the database. 9. If allowed by local regulation (e.g. the slave's device identification is verified by the database), the mobile master provides the list of channels locally available to the slave/user device. If the channel that the slave/user terminal is currently using is not included in the list of locally available channels, the slave/user device ceases all operation on its current channel. The slave/user device may scan for another Master's transmission on a different channel. 4.9. Indoor Networking In this use case, the users are inside a house or office. The users want to have connectivity to the internet or to equipment in the same or other houses / offices. This deployment scenario is typically characterized by master devices within buildings, that are connected to the Internet using a method that does not utilise TV whitespace. The master devices can establish TV whitespace links between themselves, or between themselves and one or more user devices. The figure below shows an example deployment of this scenario. Probasco & Patil Expires July 30, 2012 [Page 21] Internet-Draft PAWS: Problem, uses and requirements January 2012 \|/ | +-------+ | |TVWS |\ +-|---------+ |Usr Dev| WS AirIF \ | TVWS |\ +-------+ X|Master Dev | \ / +-----------+ \ +-------+ WS AirIF | \ +----------+ |TVWS |/ | \ (----) | Database | |Usr Dev| | \ ( ) /----------+ +-------+ WS AirIF \ / \ | X( Internet ) | / \ / +-------+ \|/ | / ( ) |TVWS |\ | | / (----) |Usr Dev| WS AirIF | | / +-------+ \ +-|---------+ / \ | TVWS | / |Master Dev |/ +-----------+ Figure 9: Example illustration of indoor TV white space use-case A simplified operational scenario utilizing TV whitespace to provide indoor networking consists of the following steps: 1. The master device powers up with its whitespace radio in idle or listen mode only (no active transmission on the whitespace frequency band). 2. The master device has internet connectivity and establishes a connection to a trusted white space database (see Section 3.1 above). 3. The master device sends its geolocation and location uncertainty information, and optionally additional information which may include (1) device ID and (2) antenna characteristics, to a trusted database, requesting a list of available whitespace channels based upon this information. 4. The database responds with a list of available white space channels that the master device may use, and optional information which may include inter alia (1) a duration of time for the use of each channel (channel validity time) (2) a maximum radiated power for each channel, (3) an indication of the quality of the spectrum for each channel and (4) directivity and other antenna information. Probasco & Patil Expires July 30, 2012 [Page 22] Internet-Draft PAWS: Problem, uses and requirements January 2012 5. Once the master device authenticates the whitespace channel list response message from the database, the master device selects one or more available whitespace channels from the list. 6. The user device(s) scan(s) the TV white space bands to locate the master device transmissions, and associates with the master. 4.10. Machine to Machine (M2M) In this use case, each "machine" includes a white space slave device and can be located anywhere, fixed or on the move. Each machine needs to have connectivity to the internet and or to other machines in the vicinity. Machine communication over a TVWS channel, whether to a master device or to another machine (slave device), is under the control of a master device. This deployment scenario is typically characterized by a master device with internet connectivity by some connection that does not utilize TV white space. The figure below shows an example deployment of this scenario. \|/ | | +-|---------+ | TVWS |\ /|Master Dev | \ / +-----------+ \ WS AirIF \ +----------+ +-------+ / \ (----) | Database | |Machine| \ ( ) /----------+ +-------+ \ / \ | X( Internet ) WS AirIF \ / | ( ) +-------+ (----) |Machine| +-------+ \ +-------+ WS AirIF-- |Machine| +-------+ Figure 10: Example illustration of M2M TV white space use-case A simplified operational scenario utilizing TV whitespace to provide machine to machine connectivity consists of the following steps: 1. The master device powers up with its whitespace radio in idle or listen mode only (no active transmission on the whitespace frequency band). Probasco & Patil Expires July 30, 2012 [Page 23] Internet-Draft PAWS: Problem, uses and requirements January 2012 2. The master device has internet connectivity and establishes a connection to a trusted white space database (see Section 3.1 above). 3. The master device sends its geolocation and location uncertainty information, and optionally additional information which may include (1) device ID and (2) antenna characteristics, to a trusted database, requesting a list of available whitespace channels based upon this information. 4. The database responds with a list of available white space channels that the master device may use, and optional information which may include inter alia (1) a duration of time for the use of each channel (channel validity time) (2) a maximum radiated power for each channel, (3) an indication of the quality of the spectrum for each channel and (4) directivity and other antenna information. 5. Once the master device authenticates the whitespace channel list response message from the database, the master device selects one or more available whitespace channels from the list. 6. The slave devices fitted to the machines scan the TV bands to locate the master transmissions, and associate with the master device. Further signaling can take place outside scope of PAWS to establish direct links among those slave devices that have associated with the master device. 5. 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 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, directly or indirectly. The databases may be country specific since the available spectrum and regulations may vary, but the fundamental operation of the protocol should be country independent. An example high-level architecture of the devices and white space databases is shown in the figure below: Probasco & Patil Expires July 30, 2012 [Page 24] Internet-Draft PAWS: Problem, uses and requirements January 2012 ----------- |WS Device| ------------ |Lat: X |\ .---. /--------|Database X| |Long: Y | \ ( ) / ------------ ----------- \-------/ \/ o ( Internet ) o ----------- /------( )\ o |WS Device| / (_____) \ ------------ |Lat: X |/ \--------|Database Y| |Long: Y | ------------ ----------- Figure 11: 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. In some countries, for example, the U.S., the regulator has determined that multiple, competing databases may provide service to White Space Devices. 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. Other aspects of a solution including provisioning the database, and calculating protected contours are considered out of scope of the initial effort, as there are significant differences between countries and spectrum bands. 5.1. 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. However the need for devices that intend to use the spectrum to communicate with a database remains a common feature. The database provides a known, specifiable Protection Contour for the primary user, not dependent on the characteristics of the White Space Device or it's ability to sense the primary use. It also provides a way to specify a schedule of use, because some primary users (for example, wireless microphones) only operate in limited time slots. Devices need to be able to query a database, directly or indirectly over the public Internet and/or private IP networks prior to operating in available spectrum. Information about available Probasco & Patil Expires July 30, 2012 [Page 25] Internet-Draft PAWS: Problem, uses and requirements January 2012 spectrum, schedule, 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. Spectrum agnostic - the spectrum used by primary and secondary users varies by country. Some spectrum has an explicit notion of a "channel" a defined swath of spectrum within a band that has some assigned identifier. Other spectrum bands may be subject to white space sharing, but only have actual frequency low/high parameters to define protected entity use. The protocol should be able to be used in any spectrum band where white space sharing is permitted. 3. 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. Since the White Space device must know it's geospatial location to do a query, it is possible to determine which database, and which rules, are applicable, even though they are country specific. 4. Address regulatory requirements - Each country will likely have regulations that are unique to that country. The messaging interface needs to be flexible to accommodate the specific needs of a regulatory body in the country where the white space device is operating and connecting to the relevant database. 5.2. 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. Probasco & Patil Expires July 30, 2012 [Page 26] Internet-Draft PAWS: Problem, uses and requirements January 2012 5.3. Protocol A protocol that enables a white space device to query a database to obtain information about available channels is needed. A device may be required to register with the database with some credentials prior to being allowed to query. The requirements for such a protocol are specified in this document. 5.4. 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. which may be country and spectrum and regulatory dependent. 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 attractive option. The intent is to evaluate the best option that meets the need for use between white space devices and databases. 6. Requirements This section is the placeholder for the requirements derived from the use cases. D. Data Model Requirements: D.1: The Data Model MUST support specifying the antenna and radiation related parameters of the subject, such as: antenna height antenna gain maximum output power, EIRP (dBm) antenna radiation pattern (directional dependence of the strength of the radio signal from the antenna spectrum mask with lowest and highest possible frequency spectrum mask in dBr from peak transmit power in EIRP, with specific power limit at any frequency linearly interpolated between adjacent points of the spectrum mask Probasco & Patil Expires July 30, 2012 [Page 27] Internet-Draft PAWS: Problem, uses and requirements January 2012 measurement resolution bandwidth for EIRP measurements D.2: The Data Model MUST support specifying an ID of the transmitter subject. This ID would contain the ID of the transmitter device that has been certified by a regulatory body for its regulatory domain. D.3: The Data Model MUST support specifying a contact or a list of contacts of this transmitter. For example, facility or on-site technical manager, administrator, any operational contacts may be specified. D.4: The Data Model MUST support specifying the location of the WSD, the uncertainty in meters and confidence in percentage for the location determination. D.5: The Data Model MUST support specifying a list of available channels and time constrains for the channel list availability. Each channel in the list shall specify the lower and upper frequency values for the channel and the time intervals the channel is available. D.6: The Data Model MUST support specifying channel availability information for a single location and for multiple locations. In the case of multiple locations, the database shall provide a channel list for each of the multiple location. P. Protocol Requirements: P.1: The protocol MUST provide a mechanism for the subject to discover the WS Database it has to use at a given location. P.2: The protocol MUST support regulatory domain discovery. P.3: The protocol between the master device and the WS Database MUST support pushing updates in channel availability changes to subjects. P.4: The protocol between the master device and the WS Database MUST support mutual authentication and authorization. P.5: The protocol between the master device and the WS Database MUST support integrity and confidentiality protection. Probasco & Patil Expires July 30, 2012 [Page 28] Internet-Draft PAWS: Problem, uses and requirements January 2012 P.6: The protocol MUST support both username/password and digital certificates based authentication. P.7: A master device MAY register with a trusted white space database. P.8: A master device MUST place its location into the query it makes to the whitespace database. P.9: A master device MUST be able to query the whitespace database for channel availability information for a specific expected coverage area around its current location. P.10: A master device MUST send Device ID, searial number and device location in the query it makes to the database. P.11: A master device MAY send additional antenna characteristic information in the query it makes to the database. P.12: A master device MUST be capable of validating the digital certificate of the WS Database. P.13: A master device MUST be capable of checking the validity of the WS Database certificate and whether it has been revoked or not. O. Operational Requirements: O.1: A master device MUST query the WS Database for the available channels as often as required by the regulation (eg, FCC requires once per day) to verify that the operating channels continue to remain available. O.2: A master device MUST determine its location along with its uncertainty (e.g., FCC requires +/-50m) and confidence level (e.g., 95%) and send it to the database so that the proper WSD position and buffer distance around the device can be added to make sure that the worst case situation required by regulations is considered in the distance calculations taking place at the database. O.3: A master device which changes its location during its operation, MUST query the WS Database for available operating channels each time it moves more than the distance specified by the regulation (e.g., FCC specifies 100m) from the location it previously made the query. Probasco & Patil Expires July 30, 2012 [Page 29] Internet-Draft PAWS: Problem, uses and requirements January 2012 O.4: The WS Database MUST provide the available channel list when requested from an authenticated and authorized device and MAY also provide time constraints, maximum output power and start and stop frequencies for each channel in the list. O.5: 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. O.6: A master device MUST be capable of validating the digital certificate of the WS Database and whether it has been revoked or not. O.7: A master device MUST be able to determine its location using latitude-longitude coordinates. O.8: A master device MUST make a fresh query of the whitespace database for the available channels within a particular time interval, using a parameter sent by the database in response to the previous query. On expiry of the time interval then a master device MUST cease transmission in the TVWS band if no successful query attempt has been made or a query has been made but the database has not responded. O.9: If slave devices change their location during operation, the master device MUST query the whitespace database for available operating channels each time a slave device moves outside the reported coverage location area. O.10: A master device MAY be able to indicate to slave devices the start and stop frequencies it has available for operation and the maximum permitted powers for the slave devices, and MAY be able to send additional optional information. 7. IANA Considerations This document has no requests to IANA. 8. Security Considerations 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 device must be certain it is Probasco & Patil Expires July 30, 2012 [Page 30] Internet-Draft PAWS: Problem, uses and requirements January 2012 talking to a bona fide database authoritative for the location and spectrum band the device operates on. The database may need to restrict interactions to devices that it has some prior relationship with, or may be restricted from providing service to devices that are not authorized in some manner. As the device will query with it's location, the location must be protected against eavesdropping. Some regulations include personally identifiable information as required elements of registration and/or query and must similarly be protected. All communications between the device and the database will require integrity protection. 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. 9. Summary and Conclusion Wireless spectrum is a scarce resource. As the demand for spectrum grows, there is a need to more efficiently utilize the available and allocated spectrum. Cognitive radio technologies enable the efficient usage of spectrum via means such as sensing or by querying a database to determine available spectrum at a given location for secondary use. White space is the general term used to refer to the bands within the spectrum which is available for secondary use at a given location. In order to use this spectrum a device needs to query a database which maintains information about the available channels within a band. A protocol is necessary for communication between the devices and databases which would be globally applicable. 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). 10. Acknowledgements The authors acknowledge Gerald Chouinard and Teco Boot as contributors to this document. Probasco & Patil Expires July 30, 2012 [Page 31] Internet-Draft PAWS: Problem, uses and requirements January 2012 11. References 11.1. Normative References [80211P] IEEE, "IEEE Standard for Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications; Amendment 6: Wireless Access in Vehicular Environments; http:// standards.ieee.org/getieee802/download/802.11p-2010.pdf", July 2010. [FCC47CFR90.210] FCC, "Title 47 Telecommunication CFR Chapter I - Federal Communication Commission Part 90 - Private Land Mobile Radio Services - Section 210 Emission masks; http:// edocket.access.gpo.gov/cfr_2010/octqtr/pdf/ 47cfr90.210.pdf", October 2010. [PAWS-PS] IETF, "Protocol to Access White Space database: Problem statement; https://datatracker.ietf.org/doc/ draft-patil-paws-problem-stmt/", July 2011. [RFC2119] IETF, "Key words for use in RFCs to Indicate Requirement Levels; http://www.rfc-editor.org/rfc/pdfrfc/rfc2119.txt.pdf", March 1997. 11.2. 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] Probasco & Patil Expires July 30, 2012 [Page 32] Internet-Draft PAWS: Problem, uses and requirements January 2012 FCC, "Federal Communications Commission, "Unlicensed Operation in the TV Broadcast Bands; http://edocket.access.gpo.gov/2010/pdf/2010-30184.pdf"", December 2010. [Ofcom Implementing] Ofcom, "Ofcom, "Implementing Geolocation; http:// stakeholders.ofcom.org.uk/consultations/geolocation/ statement/ ?utm_source=updates&utm_medium=email& utm_campaign=geolocation-statement"", September 2011. [RFC5222] IETF, Hardie, T., Netwon, A., Schulzrinne, H., and H. Tschofenig, "LoST: A Location-to-Service Translation Proto col;http://www.rfc-editor.org/rfc/pdfrfc/rfc5222.txt.pdf", August 2008. [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. [TV Whitespace Tutorial Intro] IEEE 802 Executive Committee Study Group on TV White Spaces, "TV Whitespace Tutorial Intro; http:// grouper.ieee.org/groups/802/802_tutorials/2009-03/ 2009-03-10%20TV%20Whitespace%20Tutorial%20r0.pdf", March 2009. Authors' Addresses Scott Probasco (editor) Nokia 6021 Connection drive Irving, TX 75039 USA Email: scott.probasco@nokia.com Probasco & Patil Expires July 30, 2012 [Page 33] Internet-Draft PAWS: Problem, uses and requirements January 2012 Basavaraj Patil Nokia 6021 Connection drive Irving, TX 75039 USA Email: basavaraj.patil@nokia.com Probasco & Patil Expires July 30, 2012 [Page 34]