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