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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Individual Submission B. Patil, Ed. 3 Internet-Draft 4 Intended status: Informational S. Probasco 5 Expires: January 12, 2012 G. Bajko 6 Nokia 7 B. Rosen 8 Neustar 9 July 11, 2011 11 Protocol to Access White Space database: Problem statement 12 draft-patil-paws-problem-stmt-02 14 Abstract 16 Governments around the world continue to search for new bands of 17 radio spectrum which can be used by the expanding wireless 18 communications industry to provide more services in the usable 19 spectrum. The concept of allowing secondary transmissions (licensed 20 or unlicensed) in frequencies occupied by a primary user is a 21 technique to "unlock" existing spectrum for new use. An obvious 22 requirement is that these secondary transmissions do not interfere 23 with the primary use of the spectrum. One interesting observation is 24 that often, in a given physical location, the primary user(s) may not 25 be using the entire band allocated to them. The available spectrum 26 for a secondary use would then depend on the location of the 27 secondary user. The fundamental issue is how to determine for a 28 specific location and specific time, if any of the primary spectrum 29 is available for secondary use. Academia and Industry have studied 30 multiple cognitive radio mechanisms for use in such a scenario. One 31 simple mechanism is to use a geospatial database that records the 32 primary users occupation, and require the secondary users to check 33 the database prior to selecting what part of the spectrum they use. 34 Such databases could be available on the Internet for query by 35 secondary users. This document discusses the problems that need to 36 be addressed for enabling the use of white space spectrum by 37 obtaining information from such a database. 39 Status of this Memo 41 This Internet-Draft is submitted in full conformance with the 42 provisions of BCP 78 and BCP 79. 44 Internet-Drafts are working documents of the Internet Engineering 45 Task Force (IETF). Note that other groups may also distribute 46 working documents as Internet-Drafts. The list of current Internet- 47 Drafts is at http://datatracker.ietf.org/drafts/current/. 49 Internet-Drafts are draft documents valid for a maximum of six months 50 and may be updated, replaced, or obsoleted by other documents at any 51 time. It is inappropriate to use Internet-Drafts as reference 52 material or to cite them other than as "work in progress." 54 This Internet-Draft will expire on January 12, 2012. 56 Copyright Notice 58 Copyright (c) 2011 IETF Trust and the persons identified as the 59 document authors. All rights reserved. 61 This document is subject to BCP 78 and the IETF Trust's Legal 62 Provisions Relating to IETF Documents 63 (http://trustee.ietf.org/license-info) in effect on the date of 64 publication of this document. Please review these documents 65 carefully, as they describe your rights and restrictions with respect 66 to this document. Code Components extracted from this document must 67 include Simplified BSD License text as described in Section 4.e of 68 the Trust Legal Provisions and are provided without warranty as 69 described in the Simplified BSD License. 71 Table of Contents 73 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 74 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 75 3. Prior Work . . . . . . . . . . . . . . . . . . . . . . . . . . 7 76 3.1. The concept of Cognitive Radio . . . . . . . . . . . . . . 7 77 3.2. Background information on white space in US . . . . . . . 8 78 3.3. Air Interfaces . . . . . . . . . . . . . . . . . . . . . . 8 79 4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 8 80 4.1. Global applicability . . . . . . . . . . . . . . . . . . . 9 81 4.2. Database discovery . . . . . . . . . . . . . . . . . . . . 10 82 4.3. Data model definition . . . . . . . . . . . . . . . . . . 11 83 4.4. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 11 84 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 85 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 86 7. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 87 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 88 9. Informative References . . . . . . . . . . . . . . . . . . . . 12 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 91 1. Introduction 93 Spectrum useable for data communications, especially wireless 94 Internet communications, is scarce. One area which has received much 95 attention globally is the TV white space: portions of the TV band 96 that are not used by broadcasters in a given area. In 2008 the 97 United States regulator (the FCC) took initial steps when they 98 published their first ruling on the use of TV white space, and then 99 followed it up with a final ruling in 2010[FCC ruling]. Finland 100 passed an Act in 2009 enabling testing of cognitive radio systems in 101 the TV white space. The ECC has completed Report 159 [ECC Report 102 159] containing requirements for operation of cognitive radio systems 103 in the TV white space. Ofcom published in 2004 their Spectrum 104 Framework Review [Spectrum Framework Review] and their Digital 105 Dividend Review [DDR] in 2005, and have followed up with a proposal 106 to access TV white space. More countries are expected to provide 107 access to their TV spectrum in similar ways. Any entity holding 108 spectrum that is not densely used may be asked to give it up in one 109 way or another for more intensive use. Providing a mechanism by 110 which secondary users share the spectrum with the primary user is 111 attractive in many bands in many countries. 113 The concept of allowing secondary transmissions in frequencies 114 occupied by a primary user is a technique to "unlock" existing 115 spectrum for new use. An obvious requirement is that these secondary 116 transmissions do not interfere with the primary use of the spectrum. 117 The fundamental issue is how to determine for a specific location and 118 specific time if any of the spectrum is available for secondary use. 119 There are two dimensions of use that may be interesting: space (the 120 area in which a secondary user would not interfere with a primary 121 user, and time: when the secondary use would not interfere with the 122 primary use. In this discussion, we consider the time element to be 123 relatively long term (hours in a day) rather than short term 124 (fractions of a second). Location in this discussion is geolocation: 125 where the transmitters (and sometimes receivers) are located relative 126 to one another. In operation, the database records the existing 127 user's transmitter (and some times receiver) locations along with 128 basic transmission characteristics such as antenna height, and 129 sometimes power. Using rules established by the regulator, the 130 database calculates an exclusion zone for each authorized primary 131 user, and attaches a time schedule to that use. The secondary user 132 queries the database with it location. The database intersects the 133 exclusion zones with the querier location, and returns the portion of 134 the spectrum not in any exclusion zone. Such methods of geospatial 135 database query to avoid interference have been shown to achieve 136 favorable results, and are thus the basis for rulings by the FCC and 137 reports from ECC and Ofcom. In any country, the rules for which 138 primary entities are entitled to protection, how the exclusion zones 139 are calculated, and what the limits of use by secondary entities are 140 may vary. However, the fundamental notion of recording primary 141 users, calculating exclusion zones, querying by location and 142 returning available spectrum (and the schedule for that spectrum) are 143 common. 145 In a typical implementation of geolocation and database to access TV 146 white space, a radio is configured with its location in latitude and 147 longitude. There are multiple ways to configure this location 148 information, e.g. programmed at installation (e.g. for a fixed 149 device) or determined by GPS (e.g. for a or mobile device). At 150 power-on, before the device can transmit in TV white space 151 frequencies, the device must contact a database, provide its 152 geolocation and receive in return a list of unoccupied or "white 153 space" spectrum (for example, in a TV White space implementation, the 154 list of available channels at that location). The device can then 155 select one of the channels from the list (note that it is possible 156 they list is empty; there are no unoccupied channels at the location 157 of the device) and then begins to transmit and receive on the 158 selected channel. The device must query the database again for a 159 list of unoccupied channels based on certain conditions, e.g. a fixed 160 amount of time has passed, the device has changed location beyond a 161 specified threshold. The basic scenario is that before transmitting 162 in TV white space, the device must get permission from the database. 164 This arrangement assumes that the device querying can complete a 165 query before it transmits, or some other entity is able to query the 166 database. A common arrangement for this kind of service is a fixed 167 tower with a wired infrastructure that provides Internet service to a 168 network of client devices. In this scenario, the tower has Internet 169 access from its upstream service, and can query the database for 170 channels within the tower service area. It can then provide beacon 171 service to its clients, and assign them channels within the list of 172 channels that the tower gets from the database. 174 Another arrangement might be an ad-hoc mobile network where one or 175 more members of the ad hoc network have an independent radio IP 176 connection (perhaps a commercial cellular wireless data network) 177 which can be used to query the database over the Internet. 179 A third possibility is a mechanism where the database is accessed on 180 a private IP network. 182 The low frequencies of the TV bands (470-790 MHz) have good 183 propagation characteristics. At these low frequencies, a radio 184 signal will travel ~3 times further than traditional WLAN at 2.5 GHz, 185 assuming the same transmit power. Because of these characteristics 186 and new cognitive radio techniques, when TV white space becomes 187 available, this will enable new use cases and new business 188 opportunities. Not only is the capacity of new spectrum needed, but 189 this propagation trait by itself makes TV white space attractive for 190 providing broadband wireless access in rural, sparsely populated 191 areas, as well as for extended range home hot-spot coverage (similar 192 to WLAN today, but with improved coverage). In addition to 193 propagation characteristics, the geolocation database may provide new 194 capabilities for devices that use TV white space. When a device 195 using TV white space registers its location in the database, this 196 simple act makes the location of the device available for location 197 based services. 199 Other spectrum that might also be available for sharing using white 200 space techniques exist in every country. A great many primary users 201 were allocated space a time when there were many fewer potential 202 users of the space, and the primary users are not making efficient 203 (in geospatial and time aspects) use of the space. In the past, 204 relocating existing primary users was the only feasible alternative. 205 Using white space techniques to share spectrum without imposing 206 burdens on the primary users is more attractive. 208 This document discusses the problem statement related to enabling the 209 "secondary" use of spectrum owned by a primary user without causing 210 interference to the primary user(s). One approach to avoiding 211 interference is to verify with a database about the available 212 channels and spectrum at a given location. This document also 213 identifies various issues that need to be addressed by the protocol 214 between a white space device and such a database. 216 2. Terminology 218 White Space 220 Radio spectrum which has been allocated for some primary use, but 221 is not fully occupied by that primary use at a specific location 222 and time. 224 TV White Space 226 TV white space refers specifically to radio spectrum which has 227 been allocated for over the air television broadcast, but is not 228 occupied by a TV broadcast, or other licensed user (such as a 229 wireless microphone), at a specific location and time. 231 White Space Device 233 A device which is a secondary user of some part of white space 234 spectrum. A white space device can be an access point, base 235 station, a portable device or similar. In this context, a white 236 space device is required to query a database with its location to 237 obtain information about available spectrum. 239 TV White Space 241 TV white space refers specifically to radio spectrum which has 242 been allocated for TV broadcast, but is not occupied by a TV 243 broadcast, or other licensed user (such as a wireless microphone), 244 at a specific location and time. 246 Database 248 In the context of white space and cognitive radio technologies, 249 the database is an entity which contains current information about 250 available spectrum at any given location and other types of 251 information. 253 Protected Entity 255 A primary user of white space spectrum which is afforded 256 protection against interference by secondary users (white space 257 devices( for its use in a given area and time. 259 Protected Contour 261 The exclusion area for a Protected Entity, held in the database 262 and expressed as a polygon with geospatial points as the vertices. 264 3. Prior Work 266 3.1. The concept of Cognitive Radio 268 A cognitive radio uses knowledge of the local radio environment to 269 dynamically adapt its own configuration and function properly in a 270 changing radio environment. Knowledge of the local radio environment 271 can come from various technology mechanisms including sensing 272 (attempting to ascertain primary users by listening for them within 273 the spectrum), location determination and internet connectivity to a 274 database to learn the details of the local radio environment. TV 275 White Space is one implementation of cognitive radio. Because a 276 cognitive radio adapts itself to the available spectrum in a manner 277 that prevents the creation of harmful interference, the spectrum can 278 be shared among different radio users. 280 3.2. Background information on white space in US 282 Television transmission in the United States has moved to the use of 283 digital signals as of June 12, 2009. Since June 13, 2009, all full- 284 power U.S. television stations have broadcast over-the-air signals in 285 digital only. An important benefit of the switch to all-digital 286 broadcasting is that it freed up parts of the valuable broadcast 287 spectrum. More information about the switch to digital transmission 288 is at : [DTV]. 290 With the switch to digital transmission for TV, the guard bands that 291 existed to protect the signals between stations can now be used for 292 other purposes. The FCC has made this spectrum available for 293 unlicensed use and this is generally referred to as white space. 294 Please see the details of the FCC ruling and regulations in [FCC 295 ruling]. The spectrum can be used to provide wireless broadband as 296 an example. The term "Super-Wifi" is also used to describe this 297 spectrum and potential for providing wifi type of service. 299 3.3. Air Interfaces 301 Efforts are ongoing to specify air-interfaces for use in white space 302 spectrum. IEEEs 802.11af task group is currently working on one such 303 specification. IEEE 802.22 is another example. Other air interfaces 304 could be specified in the future such as LTE. 306 4. Problem Statement 308 The use of white space spectrum is enabled via the capability of a 309 device to query a database and obtain information about the 310 availability of spectrum for use at a given location. The databases 311 are reachable via the Internet and the devices querying these 312 databases are expected to have some form of Internet connectivity, 313 directly or indirectly. The databases may be country specific since 314 the available spectrum and regulations may vary, but the fundamental 315 operation of the protocol should be country independent. 317 An example high-level architecture of the devices and white space 318 databases is shown in the figure below: 320 ----------- 321 |WS Device| ------------ 322 |Lat: X |\ .---. /--------|Database X| 323 |Long: Y | \ ( ) / ------------ 324 ----------- \-------/ \/ o 325 ( Internet ) o 326 ----------- /------( )\ o 327 |WS Device| / (_____) \ ------------ 328 |Lat: X |/ \--------|Database Y| 329 |Long: Y | ------------ 330 ----------- 332 Figure 1: High level view of the White space database architecture 334 In the figure above, note that there could be multiple databases 335 serving white space devices. The databases are country specific 336 since the regulations and available spectrum may vary. In some 337 countries, for example, the U.S., the regulator has determined that 338 multiple, competing databases may provide service to White Space 339 Devices. 341 A messaging interface between the white space devices and the 342 database is required for operating a network using the white space 343 spectrum. The following sections discuss various aspects of such an 344 interface and the need for a standard. Other aspects of a solution 345 including provisioning the database, and calculating protected 346 contours are considered out of scope of the initial effort, as there 347 are significant differences between countries and spectrum bands. 349 4.1. Global applicability 351 The use of TV white space spectrum is currently approved by the FCC 352 in the United States. However regulatory bodies in other countries 353 are also considering similar use of available spectrum. The 354 principles of cognitive radio usage for such spectrum is generally 355 the same. Some of the regulatory details may vary on a country 356 specific basis. However the need for devices that intend to use the 357 spectrum to communicate with a database remains a common feature. 358 The database provides a known, specifiable Protection Contour for the 359 primary user, not dependent on the characteristics of the White Space 360 Device or it's ability to sense the primary use. It also provides a 361 way to specify a schedule of use, because some primary users (for 362 example, wireless microphones) only operate in limited time slots. 364 Devices need to be able to query a database, directly or indirectly 365 over the public Internet and/or private IP networks prior to 366 operating in available spectrum. Information about available 367 spectrum, schedule, power, etc. are provided by the database as a 368 response to the query from a device. The messaging interface needs 369 to be: 371 1. Radio/air interface agnostic - The radio/air interface technology 372 used by the white space device in available spectrum can be 373 802.11af, 802.16, 802.22, LTE etc. However the messaging 374 interface between the white space device and the database should 375 be agnostic to the air interface while being cognizant of the 376 characteristics of various air-interface technologies and the 377 need to include relevant attributes in the query to the database. 379 2. Spectrum agnostic - the spectrum used by primary and secondary 380 users varies by country. Some spectrum has an explicit notion of 381 a "channel" a defined swath of spectrum within a band that has 382 some assigned identifier. Other spectrum bands may be subject to 383 white space sharing, but only have actual frequency low/high 384 parameters to define protected entity use. The protocol should 385 be able to be used in any spectrum band where white space sharing 386 is permitted. 388 3. Globally applicable - A common messaging interface between white 389 space devices and databases will enable the use of such spectrum 390 for various purposes on a global basis. Devices can operate in 391 any country where such spectrum is available and a common 392 interface ensures uniformity in implementations and deployment. 393 Since the White Space device must know it's geospatial location 394 to do a query, it is possible to determine which database, and 395 which rules, are applicable, even though they are country 396 specific. 398 4. Address regulatory requirements - Each country will likely have 399 regulations that are unique to that country. The messaging 400 interface needs to be flexible to accommodate the specific needs 401 of a regulatory body in the country where the white space device 402 is operating and connecting to the relevant database. 404 4.2. Database discovery 406 Another aspect of the problem space is the need to discover the 407 database. A white space device needs to find the relevant database 408 to query based on its current location or for another location. 409 Since the spectrum and databases are country specific, the device 410 will need to discover the relevant database. The device needs to 411 obtain the IP address of the specific database to which it can send 412 queries in addition to registering itself for operation and using the 413 available spectrum. 415 A database discovery mechanism needs to be specified. Reuse of 416 existing mechanisms is an option and could be adapted for meeting the 417 specific needs of cognitive radio technology. 419 4.3. Data model definition 421 The contents of the queries and response need to be specified. A 422 data model is required which enables the white space device to query 423 the database while including all the relevant information such as 424 geolocation, radio technology, power characteristics, etc which may 425 be country and spectrum dependent. All databases are able to 426 interpret the data model and respond to the queries using the same 427 data model that is understood by all devices. 429 Use of XML for specifying a data model is an attractive option. The 430 intent is to evaluate the best option that meets the need for use 431 between white space devices and databases. 433 4.4. Protocol 435 The protocol requirements are simple: registration and query 436 transactions are needed. In some circumstances, a registration 437 transaction is required prior to being able to query. The device 438 provides some identifying information, and the database responds with 439 an acknowledgement or error. The query protocol is a simple query/ 440 response action (primarily location in, available spectrum out), with 441 some error conditions. 443 It may be possible to use existing protocols (e.g. LoST [RFC5222]) 444 or it may be more appropriate to define a new protocol for this 445 purpose. HTTP transport is probably appropriate. 447 5. IANA Considerations 449 This document has no requests to IANA. 451 6. Security Considerations 453 The messaging interface between the white space device and the 454 database needs to be secured. Both the queries and the responses 455 need to be delivered securely. The device must be certain it is 456 talking to a bona fide database authoritative for the location and 457 spectrum band the device operates on. The database may need to 458 restrict interactions to devices that it has some prior relationship 459 with, or may be restricted from providing service to devices that are 460 not authorized in some manner. 462 As the device will query with it's location, the location must be 463 protected against eavesdropping. Some regulations include personally 464 identifiable information as required elements of registration and/or 465 query and must similarly be protected. 467 All communications between the device and the database will require 468 integrity protection. 470 Man-in-the-middle attacks could modify the content of a response 471 which can cause problems for other networks or devices operating at a 472 given location. Interference as well as total loss of service could 473 result from malicious information being delivered to a white space 474 device. 476 This document describes the problems that need to be addressed for a 477 messaging interface between white space devices and databases and 478 does not by itself raise any security concerns. 480 7. Summary 482 Wireless spectrum is a scarce resource. As the demand for spectrum 483 grows, there is a need to more efficiently utilize the available and 484 allocated spectrum. Cognitive radio technologies enable the 485 efficient usage of spectrum via means such as sensing or by querying 486 a database to determine available spectrum at a given locaion for 487 secondary use. White space is the general term used to refer to the 488 bands within the spectrum which is available for secondary use at a 489 given location. In order to use this spectrum a device needs to 490 query a database which maintains information about the available 491 channels within a band. A protocol is necessary for communication 492 between the devices and databases which would be globally applicable. 494 8. Acknowledgments 496 Thanks to ABC, PQR and XYZ for their comments and input which have 497 helped in improving this document. 499 9. Informative References 501 [DDR] Ofcom - Independent regulator and competition authority 502 for the UK communications industries, "Digital Dividend 503 Review; http://stakeholders.ofcom.org.uk/spectrum/ 504 project-pages/ddr/". 506 [DTV] "Digital TV Transition; http://www.dtv.gov". 508 [ECC Report 159] 509 Electronic Communications Committee (ECC) within the 510 European Conference of Postal and Telecommunications 511 Administrations (CEPT), "TECHNICAL AND OPERATIONAL 512 REQUIREMENTS FOR THE POSSIBLE OPERATION OF COGNITIVE RADIO 513 SYSTEMS IN THE 'WHITE SPACES' OF THE FREQUENCY BAND 470- 514 590 MHZ; http://www.erodocdb.dk/Docs/doc98/official/pdf/ 515 ECCREP159.PDF", January 2011. 517 [FCC ruling] 518 Federal Communications Commission, "Unlicensed Operation 519 in the TV Broadcast Bands; 520 http://edocket.access.gpo.gov/2010/pdf/2010-30184.pdf", 521 December 2010. 523 [RFC5222] Hardie, T., Newton, A., Schulzrinne, H., and H. 524 Tschofenig, "LoST: A Location-to-Service Translation 525 Protocol", RFC 5222, August 2008. 527 [Spectrum Framework Review] 528 Ofcom - Independent regulator and competition authority 529 for the UK communications industries, "Spectrum Framework 530 Review; 531 http://stakeholders.ofcom.org.uk/consultations/sfr/", 532 February 2005. 534 Authors' Addresses 536 Basavaraj Patil (editor) 537 6021 Connection drive 538 Irving, TX 75039 539 USA 541 Email: basavaraj.patil@nokia.com 543 Scott Probasco 544 Nokia 545 6021 Connection drive 546 Irving, TX 75039 547 USA 549 Email: scott.probasco@nokia.com 550 Gabor Bajko 551 Nokia 552 323 Fairchild drive 6 553 Mountain view, CA 94043 554 USA 556 Email: gabor.bajko@nokia.com 558 Brian Rosen 559 Neustar 560 470 Conrad Dr 561 Mars, PA 16046 562 USA 564 Email: brian.rosen@neustar.biz