tv white spaces cr

INTRODUCTION

Cognitive radio (CR) technology is greatly val-ued as a method of enhancing the current lowusage of limited frequency resources [1–4]. TVwhite space (TVWS) is perceived as the mostsuitable frequency bands for CR, although thetechnology is conceptually workable in any fre-quency band. TVWS refers to the TV bands at aparticular time in a particular geographic areathat are not being used by licensed services. TheFederal Communications Commission (FCC)suggested opening TVWS for unlicensed opera-tion and released a notice of proposed rulemak-ing (NPRM) in May 2004. Standardizationactivities such as IEEE 802.22, 802.11af,802.15.4m, and 802.19.1 aimed at employingunlicensed practical applications in TVWS are

ongoing [5]. Many countries also have regulatoryrequirements for both fixed andpersonal/portable TV band devices (TVBDs) tooperate in the TVWS without a license.

When wireless networks are deployed in theattractive TVWS, incumbent services, especiallydigital TV (DTV), should preferentially be pro-tected in a specified service area. Each countryhas its own service contour for DTV stations toprotect DTV service from interference. Somecountries employ a DTV protected contourbased on the field strength level of a DTVreceived signal, whereas others allow DTV ser-vice depending on the local administrative area.A TVBD operating on co-channel (N) or adja-cent channels (N±1) must be located outsidethe DTV protected contour with an additionalseparation called a keep-out distance to safelyprotect DTV services from interference byTVBDs. Exceptionally, a personal/portableTVBD operating on channels (N±1) adjacent toan active DTV channel N may be allowed tooperate within the protected contour if itstransmit power level is sufficiently low not tocause harmful interference to the DTV serviceat its position.

Within the regulatory requirements, a TVBDcan be operated on available channels in TVWSat its current location. When the TVBD tries toacquire information on the available channels,three different approaches (i.e., geo-locationand database access, spectrum sensing, andbeacon approaches) are generally considered.Most countries allowing the operation ofTVBDs presently aim for TVWS recognitionusing the geo-location and database accessmechanism. In addition, the spectrum sensingmechanism will be widely used in the nearfuture. In the spectrum sensing mode, theTVBD regards a TV band as an available chan-nel at its current location via the threshold-based hypothesis test of licensed signals [4].Ofcom has recently raised a hidden node prob-lem in TV bands to determine the reasonablespectrum sensing threshold level of a DTV sig-nal [6]. On the basis of various measurementsand analyses of DTV signals in the UK, Ofcomrecommended a hidden node margin of 35 dBin the UK. We also conduct a measurement

IEEE Communications Magazine • December 201288 0163-6804/12/$25.00 © 2012 IEEE

ABSTRACT

This article presents experimental and simu-lation results for the use of TV band devices(TVBDs) in TV white space, considering thepresence of interference by incumbent services.Digital TV (DTV) services are major incumbentservices currently operating in the TV bands.With DTV service, co-channel and adjacentchannel deployment scenarios of TVBD net-works are introduced. To safely protect theincumbent service, a minimum separation dis-tance from the DTV protected contour, which iscalled the keep-out distance, is required. Weestimate the keep-out distance for differentranges of TVBD transmit antenna height byusing several propagation models and measure-ments of ultra-high-frequency signals in Korea.We also investigate the hidden node problem forthe spectrum sensing operation mode of TVBDs.According to the results of these measurements,the hidden node margin should be at least 38 dBin order to protect DTV service. Finally, the ser-vice coverage reduction of TVBD networkscaused by neighboring DTV service is discussed.It is shown that the service coverage of a wire-less local area network system decreases about50 percent by co-channel interference fromneighboring DTV service when the field strengthof the DTV received signal is 41 dBu.

TOPICS IN RADIO COMMUNICATIONS

Kyu-Min Kang, Jae Cheol Park, Sang-In Cho, and Byung Jang Jeong,

Electronics and Telecommunications Research Institute

Young-Jin Kim, Hyoung-Jin Lim, and Gi-Hong Im, Pohang University of Science and Technology

Deployment and Coverage of CognitiveRadio Networks in TV White Space

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IEEE Communications Magazine • December 2012 89

campaign regarding the hidden node attenua-tion of DTV signals to determine the hiddennode margin in Korea.

The FCC opened up vacant TV airwaves toenable mobile wireless devices such as “superWi-Fi” technologies to utilize the attractive veryhigh frequency (VHF)/ultra high frequency(UHF) bands, which have good propagationcharacteristics. Accordingly, the service cover-age of a wireless local area network (WLAN)system can theoretically increase about 10 timescompared to existing coverage assuming thefree-space path loss when the 500 MHz TVbands are used for WLAN signal transmissioninstead of the 5 GHz frequency bands. Howev-er, TVBD service coverage may be somewhatreduced because TVBD networks are affectedby interference from DTV signals. In this arti-cle, we deal with the service coverage reductioncaused by interference from a neighboring DTVservice.

IEEE STANDARDIZATIONACTIVITIES ON TVWS

After the FCC suggested the operation of unli-censed TVBDs in vacant TV bands, IEEE 802.22first developed a standard for wireless regionalarea network (WRAN) systems using CR tech-nology [5]. The 802.22 WRAN systems can pro-vide broadband wireless access to regional, rural,and remote areas without causing harmful inter-ference to incumbent services. This standardspecifies both the physical layer (PHY) andmedium access control layer (MAC) functionali-ties of point-to-multipoint WRANs operating inthe VHF/UHF bands between 54 MHz and 862 MHz. The 802.22 WRAN adopts a simple,optimized orthogonal frequency-division multi-ple access (OFDMA) waveform and meets allthe regulatory requirements such as protectionof incumbent services, database access, andtransmit spectrum mask. The IEEE 802.11aftask group (TG) is also developing a standardfor WLAN operation in TVWS, which modifiesboth the 802.11 PHY and MAC to meet thelegal requirements for channel access and coex-istence in TVWS. The 802.15 working group hasresearched TVWS service models and wirelesspersonal area network (WPAN) applicationsoperating in TVWS. The 802.15 TG 4m is cur-rently modifying the existing 802.15.4 PHY andMAC specifications to realize power-efficientdevice command and control applications onTVWS between 54 MHz and 862 MHz.

When multiple systems are intended to usethe TVWS, a coexistence problem occurs inthe use of the available frequency band owingto differences in radio access methods betweenthe different systems. Frequency sharing inTVWS should be performed by utilizing theavailable TV band without interfering withincumbent services. To effectively solve thecoexistence problem among the family ofIEEE 802 wireless standards, the IEEE802.19.1 TG is currently developing methodsof coexistence among dissimilar or indepen-dently operated TVBD networks and dissimi-lar TVBDs.

INCUMBENT SERVICES IN TV BANDS

There are several types of TV stations, such asfull-service analog/digital TV stations, Class ATV, lower power TV, TV translators, and TVbooster stations. TV services must be protect-ed from harmful interference within specifiedcontours that depend on the type of TV sta-tion and the operating frequency band. Inaddition, many incumbent services exist in theTV bands: TV translator receive sites, cableTV headends, multichannel video program dis-tributors, radio astronomy services, and low-power auxiliary stations, including wirelessmicrophones. Digital multimedia broadcasting(DMB) services in the TV bands are now inoperation in some countries. For example, thecommercial terrestrial DMB service of Korea,with a frequency bandwidth of 1.536 MHz onthe high VHF TV channels (7–13), waslaunched in 2005. The community access TV(CATV) service should also be considered asan incumbent service in the TV bands becauseCATV systems typically utilize spectrum below1 GHz (VHF/UHF bands). Hence, direct pick-up interference may occur when a TVBDtransmit antenna is placed near a cable-con-nected TV. Above all, DTV service is the mostimportant incumbent service, especially afterthe digital switchover. In this article, we focuson DTV service among various incumbent ser-vices in the TV bands.

TVBD DEPLOYMENTSCENARIOS IN TVWS

Figure 1 shows both co-channel and adjacentchannel deployment scenarios between DTVservices and TVBDs. TVBDs must protectDTV services within the well-known DTVnoise-limited contour (grade B contour) oradministrative contour; the service contour isspecified by the regulatory body of each coun-try [6, 7]. Thus, TVBDs that intend to operateon the same frequency band should be locatedoutside the contour by at least the keep-out dis-tance to guarantee DTV reception within theDTV protected contour. Even if TVBDs oper-ate on channels (N\pm1) adjacent to an activeDTV channel (N), they must also maintain thekeep-out distance or reduce their transmitpower level to prevent adjacent channel inter-ference. In the adjacent channel, the FCC for-bids a low-power operation mode for fixedTVBDs [7].

CO-CHANNEL DEPLOYMENT SCENARIOSIn co-channel deployment scenarios, TVBD net-works should be located outside the DTV pro-tected contour by the keep-out distance toprotect DTV services from TVBD interference.To obtain the keep-out distance, we consider thedesired-to-undesired signal (D/U) ratio for co-channel TVBD interference to DTV service.Although the required D/U ratios for co-channelinterference to DTV services vary depending onthe interferers (other DTV stations and/orTVBDs), the difference is less than 0.5 dB. It isreasonable to set the D/U ratio to 15.5 dB at

To effectively solve

the coexistence

problem among the

family of IEEE 802

wireless standards,

the IEEE 802.19.1

TG is currently

developing methods

of coexistence

among dissimilar or

independently

operated TVBD

networks and

dissimilar TVBDs.


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IEEE Communications Magazine • December 201290

locations where the signal-to-interference-plus-noise ratio (SINR) is 28 dB or greater. The co-channel D/U ratio should be 23 dB around theedge of the DTV noise-limited contour, wherethe SINR is 16 dB or less [8]. The field strengthof TVBD signals measured at a DTV receivervaries depending on the antenna directionand/or polarization of both the TVBD transmit-ter and the DTV receiver. Thus, we should alsoconsider this antenna discrimination betweenthe TVBD transmitter and the DTV receiver indetermining the keep-out distance [8]. Forexample, in co-channel use of 4W fixed TVBDsin 802.22 WRAN systems, the main lobes of thedirectional DTV receive antenna and the direc-tional customer premise equipment (CPE)transmit antenna are assumed to be looking inopposite directions because the CPE is locatedoutside the DTV contour. An off-axis antennadiscrimination of 28 dB is exploited in the fixedCPE deployment scenario. On the other hand,in the fixed base station (BS) scenario, 14 dBoff-axis antenna discrimination is taken intoaccount in determining the keep-out distancebecause the DTV receive antenna main lobe islooking away from the omni-directional BStransmit antenna. For 100 mWpersonal/portable TVBDs, because the DTVreceive antenna main lobe is looking away fromthe omni-directional CPE or the BS transmitantenna, only 14 dB off-axis antenna discrimina-tion is considered [8]. The keep-out distanceshould be determined using the required D/Uratio, antenna discrimination associated with thedeployment scenario of TVBDs and DTVreceivers, and transmit power level of theTVBDs in order to protect DTV reception fromco-channel TVBD interference. Co-channeloperation is allowed when the TVBD networksmaintain at least this separation distance fromthe DTV protected contour.

ADJACENT CHANNEL DEPLOYMENT SCENARIOS

To operate on the adjacent channels, TVBDsmust maintain the keep-out distance from theDTV protected contour as in the co-channeldeployment case. To determine the keep-out dis-tance for adjacent channel deployment, the sameoff-axis antenna discrimination factor as in theco-channel case is employed. The recommendedD/U ratio for adjacent channel protection is –33 dB [8]. Additionally, the FCC has allowedpersonal/portable TVBDs to operate on adjacentchannels within the DTV protected contour onlyif their maximum conducted output power doesnot exceed 40 mW (Fig. 1). In this case, the off-axis antenna discrimination between the DTVreceive antenna and the TVBD transmit antennawould no longer be available. Note that, foroperation in an adjacent channel within theDTV protected contour, the nominal minimumseparation distance between the DTV receiveantenna and the TVBD transmit antenna isassumed to be 10-20 m [7, 8].

HOW TOPROTECT DIGITAL TV SERVICE

To guarantee the protection of the incumbentDTV services, a TVBD should be located out-side the DTV protected contour by the keep-outdistance. This distance depends mainly on themaximum allowable equivalent isotropically radi-ated power (EIRP), the operation mode (fixedor personal/portable mode), and the transmitantenna height of the TVBDs. The transmitpower of TVBDs deployed within the protectedcontour on adjacent channels should be suffi-ciently reduced not to cause harmful interfer-ence to the incumbent DTV service. A TVBDusing the spectrum sensing mode identifies avail-able channels via the threshold-based hypothesis

Figure 1. Deployment scenarios of co-channel and adjacent channel TV band devices in TV white space.

Fixed TVBD (4W)

Channel(N±1)

Channel(N)

Channel(N±1)

Channel(N)

Channel (N)

Ch. (N)

Protectedcontour

TV station

Channel (N)

Keep-out distance

Keep-out distance

Ch. (N±1)

Ch. (N±1) Ch. (N±1)

Personal/portable TVBD (40 mW)

Personal/portable TVBD (100 mW)

Ch. (N±1)

Ch. (N)

To operate on the

adjacent channels,

TVBDs must maintain

the keep-out dis-

tance from the DTV

protected contour as

in the co-channel

deployment case. To

determine the keep-

out distance for

adjacent channel

deployment, the

same off-axis

antenna discrimina-

tion factor as in the

co-channel case is

employed.


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test of incumbent signals [4]. If the sensingthreshold is improperly chosen, the TVBD maymisjudge an occupied TV band as an availablechannel and thus cause severe interference tothe incumbent service. Therefore, the geographi-cal characteristics, local shape of each area, andradio propagation environments of each countryshould be considered when determining thespectrum sensing threshold level of incumbentservices.

DTV PROTECTED CONTOURA DTV station’s service coverage depends onthe DTV transmission effective radiated power(ERP), transmit antenna height above averageterrain (HAAT), operating frequency band, andso on. When an Advanced Television SystemsCommittee (ATSC) DTV system operates onchannel 38 (614–620 MHz) with a transmitantenna HAAT of 500 m and a 1000 kW ERP,the service coverage is expected to be about 135 km, as estimated by the InternationalTelecommunication Union RadiocommunicationSector (ITU-R) P.1546-4 propagation model [9].In the US and Canada, DTV service is availablein the area within the grade B contour, wherethe field strength values are 28 dBu (low VHF),36 dBu (high VHF), and 41 - 20log[615/channelmid-frequency in MHz] dBu (UHF) [8]. Howev-er, in other countries, such as Korea, where TVbroadcasting services are based on local TV net-works, a DTV service is allowed within a prede-termined local administrative area instead of anarea defined by the field strength level of theDTV received signal. Thus, the field strength ofa DTV signal operating on the UHF TV broad-cast band would be much larger than 60 dBu insome fringe areas of the administrative contourin Korea, whereas the field strength can be lessthan 41 dBu in other areas of the administrativecontour. In this case, it is desirable to carefullydetermine interference protection requirementsbased on both the administrative contour andthe noise-limited contour (grade B contour)because the DTV service available area is quitedifferent from the permissible area.

KEEP-OUT DISTANCEFigure 2 compares the co-channel keep-out dis-tances of 4 W fixed TVBDs from the DTV con-tour for different ranges of TVBD transmittingantenna HAAT estimated using the Okumurapropagation model, FCC F(50,10) propagationcurve, ITU-R P.1546-4 propagation model, andpropagation measurement of UHF signals inKorea [8, 10]. The Okumura model is one of themost popular macroscopic propagation modelsbased on measurements in and around Tokyo[10]. This model was designed for use in the fre-quency range between 150 MHz and 1920 MHzand mostly in urban areas. For various propaga-tion environments, the correction factors by areatypes, such as suburban, quasi-open, and open,are also included in the model. F(50,10) meansthat the field strength is obtained by the FCCpropagation curve at 50 percent of the potentialreceiver locations for at least 10 percent of thetime. In the estimation of co-channel keep-outdistances, we assume that the field strength(channel 38) of the DTV contour is 41 dBu. The

required D/U ratio for co-channel protection atthe contour is 23 dB. The antenna discrimina-tion between the DTV receive and the TVBDtransmit antennas is 14 dB. As shown in the fig-ure, the estimated keep-out distances calculatedwith the FCC propagation curve are similar tothe results using the ITU-R P.1546-4 propaga-tion model. In addition, the estimated keep-outdistances based on the measurements in Koreahave many similarities with the results for the“quasi-open, large city” case in the Okumurapropagation model. Note that the FCC recentlyrevised the keep-out distances between fixedTVBDs and the DTV protected contour of co-channel and adjacent channel TV stations forantenna HAAT values ranging from less than 3 m to a maximum of 250 m [7].

HIDDEN NODE MARGINCurrently, most countries opening up the TVWShave an initial plan to detect available TV chan-nels by the geo-location and database accessmechanism. In the near future, a TVBD isexpected to obtain information on the availableTV channels from a TV band database in areaswhere it can access the database. In other areas,the TVBD can obtain available TV channels bythe spectrum sensing mechanism. In the spec-trum sensing mode, the TVBD may miss todetect DTV signals because of surroundingbuildings or barriers even though DTV service isactive in the area. When the TVBD uses theDTV frequency band, regarding it as an avail-able TV channel according to wrong sensingresult, it may cause severe interference to theDTV service. To address this problem, a hiddennode margin should be considered when deter-mining the DTV sensing threshold level.

We investigated the hidden node marginrequired to efficiently utilize TVBD networks in

Figure 2. Comparison of co-channel keep-out distances of fixed TVBDs fromthe DTV contour for different ranges of TVBD transmitting antenna HAATestimated using the Okumura propagation model, FCC F(50,10) propagationcurve, ITU-R P.1546-4 propagation model, and propagation measurement ofUHF signals in Korea.

TVBD transmitting antenna HAAT (m)200

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Okumura, open, large cityOkumura, Quasi open, medium cityOkumura, Quasi open, large cityOkumura, suburban, medium cityOkumura, suburban, large cityOkumura, urban, medium cityOkumura, urban, large cityITU-R 1546-4FCCMeasured in Korea


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the TVWS and also to protect DTV service inKorea. To determine the hidden node margin,each country should consider its own geographi-cal characteristics, the local shape of each area,and the radio propagation environment. First,we classified the radio propagation environmentinto urban, basin, and coastal areas on the basisof the geographical characteristics. We also con-sidered eight local shapes: commercial buildings,apartments, residential and commercial build-ings, villas, housing, parks, quasi-open fields, andindustrial complexes. We then measured andanalyzed hidden node attenuation for each localshape in each classified geographic area. Figure3 shows the hidden node attenuation of DTVsignals for the eight local shapes in Korea.Because commercial buildings or apartments inlarge cities in Korea are located in close proxim-ity to each other, the hidden node margin shouldbe at least 38 dB in order to safely protect DTVservice. This result is 3 dB higher than the 35 dBhidden node margin in the UK suggested byOfcom [6].

TVBD SERVICE COVERAGE CHANGEDUE TO NEIGHBORING DTV SERVICEAs discussed earlier, DTV service can be provid-ed without harmful interference from TVBDnetworks when the TVBD networks aredeployed outside the DTV protected contour bymore than the keep-out distance. However, it isnot guaranteed that the TVBD networks areproperly operated in this deployment scenario.Thus, we investigated the service coveragechange in a TVBD network considering interfer-ence from neighboring DTV stations.

Figure 4 illustrates the simulation model forestimating the service coverage of an 802.11-TGaf-based TVBD network. We consider theworst-case coverage scenario in which the high-est interfering power from a DTV station can bemeasured at a personal/portable TVBD mobilestation (MS). The simulation parameters aresummarized in Table 1. In Korea, because theprotected contour of DTV service is determinedby the local administrative area, the receivedpower of an incumbent DTV service at the pro-tected contour may not meet the exact grade Blevel (e.g. 41 dBu). Thus, we consider differentlevels of the received power of DTV signals,PDTV RX, near that of the grade B in order toconsider the various protected contours, i.e.PDTV RX [dBm] Œ {–94, –84, –74, –64}. FromPDTV RX, we obtained the protected contour ofthe DTV service by using the ITU-R P.1546-4propagation model at 50 percent of the locationsfor 90 percent of the time in the simulation [9].To evaluate the keep-out distance for a fixedTVBD BS, the Okumura propagation model fora quasi-open area and a large city in Fig. 2 wasused. Considering the keep-out distance, thelocation of the TVBD BS can be determined asin Fig. 4. The transmit powers of the fixedTVBD, portable TVBD, and DTV station are100 mW, 100 mW, and 2.5 kW, respectively. Inthis scenario, we assume that the transmit powerlevel of the fixed TVBD BS is 100 mW insteadof 4 W EIRP to avoid downlink-uplink coverage

Figure 3. Hidden node attenuation of DTV signals in Korea; measurementswere conducted for eight local shapes in each classified geographic area(urban, basin, and coastal areas) in Korea.

Hidden node attenuation (dB)50

10

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perc

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20

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10 15 20 25 30 35 40

Commercial buildingApartmentResidential and commercial buildingVillaHousingParkQuasi-open fieldIndustrial complex

Figure 4. Simulation methodology for estimating the worst-case TVBD servicecoverage.

Undesired signal (U)Desiredsignal

(D)

D/Uratio

Protectedcontour

Interference (I)

Datasignal

(S)

SINR[S/(I+N)]

Noise (N)

CoverageKeep-out distancefor portable TVBD

Keep-out distancefor fixed TVBD

BSMSDTV userDTV station

Figure 5. Service coverage of a TVBD network for different ranges of TVBDBS transmitting antenna height with various protected contours.

Height of TVBD BS antenna (m)200

0.2

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ser

vice

cov

erag

e (k

m)

0.4

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40 60 80 100

In the absence of DTV interferencePDTV RX = -94 dBmPDTV RX = -84 dBm (grade B)PDTV RX = -74 dBmPDTV RX = -64 dBm


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imbalance with the personal/portable TVBD MSof 100 mW. The transmit antenna height of theDTV station is 500 m. When the service cover-age of a TVBD network is calculated, the ITU-RP.1411-4 propagation model assuming the lowerbound in a line-of-sight environment [11] is usedto estimate the received signal power. The rea-son is that an 802.11 TGaf system is expected tocover the short range as a micro cell outdoors.The path loss of the interfering signal from theDTV station to the TVBD MS is calculatedusing the ITU-R P.1546-4 model [9] at 50 per-cent of the locations for 10 percent of the time.Then, we can obtain a SINR of the TVBD MSlocated dBS–MS. The packet error ratio of 802.11systems must be 10 percent or less when thephysical layer service data unit length is 1000octets. We assume that the SINR required tosupport the lowest level of the modulation andcoding set for 802.11-TGaf-based systems (e.g.binary phase shift keying and 1/2 code-rate) is 4 dB, with a receiver noise figure of 10 dB andan implementation margin of 5 dB [12]. Thus,when the received SINR of the TVBD MS atthe position of the MS with a separation ofdBS–MS from the BS meets the target value, theservice coverage of a TVBD network can be esti-mated as the distance between the BS and theMS.

Figure 5 shows the estimated service cover-age of a TVBD network for different ranges ofthe TVBD BS transmitting antenna height withvarious protected contours. The result of PDTV RX = –84 dBm corresponds to TVBD ser-vice coverage with the grade B level of theDTVprotected contour. The service coveragewith the grade B contour is about 500 m whenthe transmit antenna height of the TVBD BS is30 m. Note that the calculated DTV protectedcontour becomes shorter as the received powerof the DTV signal at the contour increases. TheTVBD has the longest coverage when thereceived power is –94 dBm because the interfer-ence power is lowest then. When the transmitantenna height of the TVBD BS is 50 m, thecoverage with PDTV RX = –94 dBm is almost 1 km and has a gap of about 400 m compared tothat without DTV interference. From the simu-lation results, we conclude that the service cov-erage of a TVBD network has various rangeswhen the field strength of the DTV protectedcontour is fixed not at the exact grade B levelbut at various levels according to local adminis-trative contours.

CONCLUSIONSIn this article, we presented co-channel andadjacent channel deployment scenarios ofTVBDs or TVBD networks in the TVWS.TVBDs should be operated outside the DTVprotected contour by at least the keep-out dis-tance to guarantee DTV service. We calculatedco-channel keep-out distances from the DTVcontour for various ranges of TVBD transmitantenna height by using several propagationmodels and measurements of UHF signals inKorea. The hidden node margin in Korea wasalso measured and discussed in terms of effec-tive utilization of the spectrum sensing mode in

TVBD networks. The coverage of TVBD net-works was estimated considering the interfer-ence from a neighboring DTV service.

ACKNOWLEDGEMENTThis research was supported by the KCC (KoreaCommunications Commission), Korea, under theR&D program supervised by the KCA (KoreaCommunications Agency) (KCA-2012-09911-01105). This research was also supported byBasic Science Research Program through theNational Research Foundation of Korea (NRF)funded by the Ministry of Education, Scienceand Technology (No. 2012-0005457).

REFERENCES[1] S. Haykin, “Cognitive Radio: Brain-empowered Wireless

Communications,” IEEE JSAC, vol. 23, no. 2, Feb. 2005,pp. 201–20.

[2] T. W. Yune et al., “SC-FDMA with Iterative MultiuserDetection: Improvements on Power/Spectral Efficiency,”IEEE Commun. Mag., vol. 48, no. 3, Mar. 2010, pp.164–71.

[3] D. Y. Seol, T. W. Yune, and G. H. Im, “Primary NetworkCognition with Spatial Diversity Signature,” IEEE Com-mun. Lett., vol. 13, no. 5, May 2009, pp. 321–23.

[4] H. J. Lim, D. Y. Seol, and G. H. Im, “Joint Sensing Adap-tation and Resource Allocation for Cognitive Radio withImperfect Sensing,” IEEE Trans. Commun., vol. 60, no.4, Apr. 2012, pp. 1091–100.

Table 1. Simulation parameters.

DTV Parameter Value

Center frequency of DTV Tx 617 MHz (Ch. 38)

Field strength at grade B contour 41 dBu (–84 dBm)

D/U ratio at noise-limited contour 23 dB

DTV Rx antenna discrimination 14 dB

DTV ERP 2.5 kW

Height of DTV Tx antenna 500 m

Height of DTV Rx antenna 10 m

TVBD Parameter Value

Channel spacing of TVBD 4 MHz

TVBD BS EIRP 100 mW

TVBD MS EIRP 100 mW

Height of TVBD BS antenna 3, 10, 20, 30, …, 90, 100 m

Height of TVBD MS antenna 1.5 m

Thermal noise (for 4 MHz bandwidth) –108 dBm

Receiver noise figure 10 dB

Noise power [N] –98 dBm

Target SINR for coverage estimation 4 dB


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[5] K. G. Shin et al., “Cognitive Radios for Dynamic Spec-trum Access: from Concept to Reality,” IEEE WirelessCommun., vol. 60, no. 4 Dec. 2010, pp. 64–74.

[6] Ofcom, “Digital Dividend: Cognitive Access, Statementon License-Exempting Cognitive Devices using Inter-leaved Spectrum,” Statement, July 2009.

[7] FCC, “Third Memorandum Opinion and Order, In theMatter of Unlicensed Operation in the TV BroadcastBands, Additional Spectrum for Unlicensed DevicesBelow 900 MHz and in the 3 GHz Band,” ET DocketNo. 12-036, Apr. 2012.

[8] G. L. StÅNuber, S. M. Almalfouh, and D. Sale, “Interfer-ence Analysis of TV-Band Whitespace,” Proc. IEEE, vol.97, no. 4, pp. 741–54, Apr. 2009.

[9] ITU-R Recommendation P.1546-4, “Method for Point-to-Area Predictions for Terrestrial Services in the FrequencyRange 30 MHz to 3000 MHz,” Tech. Rep., the ITURadiocommunication Assembly, 2009.

[10] Y. Okumura et al., “Field Strength and Its Variability inVHF and UHF Land-Mobile Radio Service,” Review ofthe Electrical Comm. Laboratory, vol. 16, no. 9–10,Sept.–Oct. 1968, pp. 825–73.

[11] ITU-R Recommendation P.1411-4, “Propagation Dataand Prediction Methods for the Planning of Short-Range Outdoor Radiocommunication Systems andRadio Local Area Networks in the Frequency Range 300MHz to 100 GHz,” Tech. Rep., the ITU radiocommuni-cation assembly, 2007.

[12] IEEE Draft P.802.11-REVmb/D9.0, “IEEE Standard forInformation Technology, Telecommunications andInformation Exchange between Systems, Local andMetropolitan Area Networks, Specific Requirement Part11: Wireless LAN MAC and PHY Specifications,” May2011.

BIOGRAPHIESKYU-MIN KANG received the B.S., M.S., and Ph.D. degrees inelectronic and electrical engineering from Pohang Universi-ty of Science and Technology (POSTECH), Kyungbuk, Korea,in 1997, 1999, and 2003, respectively. Since 2003, he hasbeen with Electronics and Telecommunications ResearchInstitute (ETRI), Daejeon, Korea. His current research inter-ests include cognitive radio networks, spectrum engineer-ing, digital signal processing, and high-speed digitaltransmission systems.

YOUNG-JIN KIM received the B.S. degree in electronic andelectrical engineering from Pohang University of Scienceand Technology (POSTECH), Kyungbuk, Korea, in 2007. Heis currently working toward the Ph.D. degree at Communi-cations Research Laboratory, POSTECH. His current researchinterests are MIMO systems, spectrum sharing, and cogni-tive radio networks.

JAE CHEOL PARK received the B.S. degree in electronics engi-neering and the M.S.E. degree in electronics and radioengineering from the Kyung Hee University, Yongin, Korea,in 2009 and 2011, respectively. He is currently a memberof engineering staff at the Radio Technology ResearchDepartment, Electronics and Telecommunications ResearchInstitute (ETRI), Daejeon, Korea. His research interests

include cognitive radio and cooperative networks, mobilecommunications, and MIMO systems.

SANG-IN CHO received the B.S., and M.S. degrees in infor-mation and telecommunication engineering from ChonbukNational University, Korea, in 1997, and 1999, respectively.Since 1999, he has been with Electronics and Telecommu-nications Research Institute (ETRI), Daejeon, Korea. His cur-rent research interests include spectrum engineering, VLSIdigital signal processing and digital communications.

BYUNG JANG JEONG received his B.S. degree from KyungpookNational University, Daegu, Korea, in 1988, and his M.Sc.and Ph.D. degrees in electrical engineering from KoreaAdvanced Institute of Science and Technology (KAIST) in1992 and 1997, respectively. He was with SamsungAdvanced Institute of Technology (SAIT) from 1994 to2003. Since 2003, he has been with Electronics andTelecommunications Research Institute (ETRI) as a principalmember of research staff. His research interests include sig-nal processing for wireless communications, MIMO sys-tems, and cognitive radio networks

HYOUNG-JIN LIM received the B.S. degree in electronic andelectrical engineering from Pohang University of Scienceand Technology (POSTECH), Kyungbuk, Korea, in 2006. Heis currently working toward the Ph.D. degree at Communi-cations Research Laboratory, POSTECH. His current researchinterests are radio resource management, dynamic spec-trum access, and cognitive radio networks.

GI-HONG IM [M’87, SM’94] ([email protected]) was withAT&T Bell Laboratories, Holmdel, NJ, where he was respon-sible for the design and implementation of high-speed dig-ital transmission systems for loop plant, local area network,and broadband access applications (1990–1996). He hasauthored or co-authored more than twenty standards con-tributions to standards organizations such as ANSI T1E1.4,ETSI, IEEE 802.9, ANSI X3T9.5, and the ATM Forum. Thesecontributions have led to the adoption of three AT&T pro-posals for new standards for high-speed LANs and broad-band access. In 1995, he was appointed as DistinguishedMember of Technical Staff at AT\&T Bell Laboratories. Since1996, he has been with POSTECH as a professor. From1996 to 2000, he was a Bell Laboratories Technical Consul-tant. From 2002 to 2003, he was a visiting vice presidentof Samsung Electronics, where he worked on 4G wirelesscommunication systems. His current research interestsinclude signal processing and digital communications withapplications to high-speed digital transmission systems. Hereceived the 1996 Leonard G. Abraham Prize Paper Awardfrom the IEEE Communications Society for the paper enti-tled “Bandwidth-efficient digital transmission over unshield-ed twisted pair wiring,” published in the IEEE Journal onSelected Areas in Communications, the 2000 LG Awardfrom LG Electronics, and the 2005 National Scientist Awardfrom the Korean government. From 2004 to 2010, heserved as an editor for the IEEE Transactions on Communi-cations and an associate editor for IEEE CommunicationsLetters. Currently, he is serving as a division editor for theJournal of Communications and Networks. He has 24 U.S.patents granted or pending.

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