Robert J. Kerczewski and Jeffrey D. Wilson

Glenn Research Center, Cleveland, Ohio

William D. Bishop

Verizon, Cleveland, Ohio

Assessing Spectrum Compatibility for

Beyond-Line-of-Sight UAS Control

and Non-Payload Communications

NASA/TM—2014-218407

November 2014
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Robert J. Kerczewski and Jeffrey D. Wilson

Glenn Research Center, Cleveland, Ohio

William D. Bishop

Verizon, Cleveland, Ohio

Assessing Spectrum Compatibility for

Beyond-Line-of-Sight UAS Control

and Non-Payload Communications

NASA/TM—2014-218407

November 2014

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Prepared for the

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This report contains preliminary ¿ ndings, 

subject to revision as analysis proceeds.
NASA/TM—2014-218407 1 

Assessing Spectrum Compatibility for Beyond-Line-of-Sight 

UAS Control and Non-Payload Communications 

Robert J. Kerczewski and Jeffrey D. Wilson 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 

William D. Bishop 

Verizon 

Cleveland, Ohio 44135 

Abstract 

In order to provide for the safe integration of unmanned 

aircraft systems (UAS) into the National Airspace System 

(NAS), the control and non-payload communications (CNPC) 

link must be highly reliable. A specific requirement is that it 

must operate using aviation safety radiofrequency spectrum. 

Two types of links are required – line-of-sight (LOS) using 

terrestrial-based communications and beyond-line-of-sight 

(BLOS) using satellite communications. The 2012 World 

Radiocommunication Conference (WRC-12) provided a 

suitable allocation for LOS CNPC spectrum in the 5030 to 

5091 MHz band which, when combined with a previously 

existing allocation fulfills the LOS spectrum requirement. The 

5030 to 5091 MHz band is also allocated for BLOS CNPC, 

but since a significant portion of that band is required for LOS 

CNPC, additional BLOS spectrum is required. More critically, 

there are no satellites in operation or in development to 

provide such services in that band. Hence BLOS CNPC 

cannot be provided in protected aviation spectrum under 

current conditions. To fill this gap and enable integration of 

UAS into the NAS, it has been proposed to allow CNPC to 

operate over certain Fixed Satellite Service (FSS) bands in 

which many satellites currently provide commercial services. 

To enable this, changes in international regulation must be 

enacted. Agenda Item 1.5 of the 2015 WRC examines the 

possible regulatory changes needed. As part of the 

examination process, sharing between potential UAS using 

satellite communications for BLOS CNPC and other services 

allocated to the FSS bands being considered must be studied. 

This paper reviews the technical requirements and approach 

being undertaken for these sharing studies, with emphasis on 

study of interference from UAS into digital repeater links 

operating under the Fixed Service allocation. These studies are 

being conducted by NASA Glenn Research Center. 

Introduction 

Many potential applications for civil use of unmanned 

aircraft system (UAS) have been identified, with additional 

use concepts emerging almost daily. However, the ability of 

UAS to operate in the National Airspace System (NAS), in 

particular in non-segregated airspace, faces many obstacles. 

The increasing pressure to remove these obstacles has resulted 

in the establishment of a national goal in the US of enabling 

UAS to have routine access to the NAS. Among a number of 

technical barriers that must be overcome to meet this goal is 

the absence of standard, certifiable communications links 

supplying the control and non-payload communications 

(CNPC) function, essentially providing the link over which a 

pilot on the ground can control the unmanned aircraft (UA). 

The International Civil Aviation Organization (ICAO) has 

determined that the CNPC link must operate over protected 

aviation spectrum. Therefore protected aviation spectrum must 

be allocated for this function, approved through the processes 

of the International Telecommunications Union 

Radiocommunication Sector (ITU-R). 

Spectrum requirements have been met for line-of-sight 

(LOS) CNPC through actions taken at the ITU-R’s 2012 

World Radiocommunication Conference (WRC-12). However 

for beyond-line-of-sight (BLOS) CNPC, sufficient protected 

aviation spectrum has not been allocated. Agenda Item 1.5 

(AI 1.5) for the 2015 WRC (WRC-15) looks into the possible 

use of commercial satellites operating under the Fixed 

Satellite Service (FSS) allocation to meet spectrum 

requirements for BLOS CNPC. However since this allocation 

is not protected aviation spectrum, regulatory issues must be 

put in place for such use to be approved. This is the primary 

issue being addressed by AI 1.5. 

Studies are underway and regulatory proposals are being 

developed to address Agenda Item 1.5. These include 

characterization of CNPC technical and operational aspects, 

definition of performance requirements, and studies of 

spectrum compatibility between CNPC and other services in 

these bands. NASA’s UAS in the NAS Project is contributing 

to these activities by performing spectrum compatibility and 

sharing studies between unmanned aircraft satellite earth 

stations and terrestrial services which share the Ku-Band and 

Ka-Band spectrum. The compatibility studies being 

undertaken by NASA are submitted to the preparation process 

for the 2015 WRC and then refined and updated based on 

decisions made by the ITU-R meeting participants. 

This paper will expand on the background of the BLOS 

CNPC and spectrum requirements and then focus on the nature 

of the spectrum compatibility problem, the approach and 

methodologies being applied to the studies, and example results. 
NASA/TM—2014-218407 2 

Spectrum Requirements and Solutions 

Spectrum requirements were established with the adoption 

of Report M.2171 by the ITU-R (Ref. 1). In this report, the 

requirements of 34 MHz for UAS LOS and 56 MHz for UAS 

BLOS (satellite) were identified. Actions taken at the ITU’s 

WRC-12 have established sufficient spectrum resources to 

meet the LOS spectrum requirement with a new Aeronautical 

Mobile (Route) Service (AM(R)) allocation in the 5030 to 

5091 MHz band combined with a portion of an existing 

AM(R)S allocation in the 960 to 1164 MHz band. The BLOS 

spectrum requirement remains unfulfilled. A previously 

existing Aeronautical Mobile Satellite (Route) Service 

(AMS(R)S) allocation in the 5030 to 5091 MHz band meets a 

portion of the requirement, however communication satellites 

required to provide service in this band do not exist and none 

are currently planned. As a result, the UAS community is 

searching for a solution to meet the BLOS CNPC needs. 

The most likely solution is to use existing satellites 

operating under the Fixed Satellite Service (FSS), of which 

many operate in several bands. Given the size of most 

unmanned aircraft, higher frequency bands are required in 

order to have antennas small enough to fit onto the aircraft. 

Therefore the use of FSS in Ku-Band (12 to 18 GHz) and KaBand (26.5 to 40.0 GHz) for BLOS CNPC has been proposed. 

Agenda Item 1.5 for the 2015 WRC (WRC-15) examines this 

proposal and what regulatory requirements would need to be 

addressed to allow such an application in those bands. 

WRC-15 Agenda Item 1.5 

At WRC-12, Resolution 153 was adopted: “To consider the 

use of frequency bands allocated to the fixed-satellite service 

not subject to Appendices 30, 30A, and 30B for the control 

and non-payload communications of unmanned aircraft 

systems (UAS) in non-segregated airspaces.”

The resolution (Ref. 2) considers the possible regulatory 

actions to support the use of FSS frequency bands for the UAS 

CNPC links ensuring their safe operation, including the 

necessary studies leading to technical, regulatory and 

operational recommendations and sharing and compatibility 

studies with services already having allocations in those bands. 

ITU-R has chartered Working Party 5B (WP5B) to develop 

the documents and proposals for AI 1.5 that will be considered 

for approval at WRC-15. Sharing studies, including those 

under development by NASA, are submitted through WP5B. 

Sharing Studies for Agenda Item 1.5 

The sharing studies involved in AI 1.5 include several 

scenarios and frequency ranges in the Ku- and Ka-Band FSS 

Bands. These were proposed for further study at WRC-12 and 

subsequently approved for full analysis with results to be 

shared and reviewed at WRC-15 as AI 1.5. NASA’s Glenn 

Research Center (GRC) has been requested to conduct sharing 

studies on UAS Control and Non-Payload (CNPC) Link 3 and 

the potential interference, Path 3s, shown in Figure 1. The 

frequency bands under study for Link 3 are 14.0 to 14.5 GHz 

in Ku-Band and 27.5 to 30.0 GHz in Ka-Band. 

Sharing Study Scenarios for 14.0 to 14.5 GHz 

Based on the existing allocations in 14.0 to 14.5 GHz for 

terrestrial co-primary services, three interference scenarios 

exist: 

x Interference from UAES uplink transmitters into Fixed 

Service (FS) (i.e., terrestrial microwave) receivers at 

14.3 to 14.5 GHz; 

x Interference from UAES uplink transmitters into Mobile 

Service (MS) (except aero mobile) receivers at 14.3 to 

14.5 GHz; 

x Interference from UAES uplink transmitters into 

Radionavigation Service (RNS) receivers at 14 to 

14.3 GHz. 

Sharing Studies Conducted Based on Available 

System Characteristics for 14.0 to 14.5 GHz 

No technical characteristics of land mobile systems in the 

land mobile service for the frequency band 14.0 to 14.5 GHz 

are available, so no sharing study is being conducted for the 

mobile service. Similarly WP5B has not identified any current 

radionavigation uses of the 14.0 to 14.3 GHz band. Therefore, 

equipment parameters are not available for consideration in 

frequency sharing studies and no sharing study is being 

conducted for the radio navigation service. The sharing study 

in the 14.0 to 14.5 GHz band is therefore limited to 

interference from UAES (UA Earth Station) uplink 

transmitters into the fixed service receivers at 14.3 to 

14.5 GHz. 

Sharing Study Scenarios for 27.5 to 30.0 GHz 

Based on the allocations, two interference scenarios exist: 

x Interference from UA uplink transmitters into Fixed 

Service (i.e., P-P terrestrial microwave) receivers at 27.5 

to 29.5 GHz; 

x Interference from UA uplink transmitters into 

Mobile Service (except aero mobile) receivers at 27.5 to 

29.5 GHz. 

There are no fixed, mobile or other terrestrial services 

allocated in the 29.5 to 30.0 GHz band, so no sharing studies 

are needed for this portion of the 27.5 to 30.0 GHz band. 
NASA/TM—2014-218407 3 

Figure 1.—NASA studying link 3 and potential interference, from Reference 3.

Sharing Studies Conducted Based on Available 

System Characteristics for 27.5 to 30.0 GHz 

No technical characteristics of land mobile systems in the 

land mobile service for the frequency band 27.5 to 29.5 GHz 

are available. Therefore no analysis is conducted for the 

mobile service. 

The sharing study in the 27.5 to 30.0 GHz band is therefore 

limited to interference from UA earth station uplink 

transmitters into the fixed service receivers in 27.5 to 

29.5 GHz. 

Flight Scenarios 

Relevant UAS flight scenarios have been provided by the 

International Civil Aviation Organization for use in the 

sharing studies (Ref. 3). Based on the flight scenario 

descriptions, scenarios 2 and 7 identify the altitudes required 

for the sharing studies for the UAES transmitter-FS receiver 

case as shown in Table 1. 

TABLE 1.—UAS FLIGHT SCENARIOS 

FOR SHARING STUDIES 

ICAO Scenario 2 7 

 Medium altitude 

surveillance/ 

Aerial work 

(search pattern) 

Departure descent 

above 3000 ft 

above ground 

level (AGL) 

Max altitude (feet 

above MSL, unless 

otherwise specified) 

30 000 19 000 

Min altitude (feet 

above MSL, unless 

otherwise specified) 

19 000 3 000 

Max latitude (deg) 70 70 

 
NASA/TM—2014-218407 4 

The Sharing Case of UA Earth Station 

Uplinks 

The ITU-R has established interference criteria to protect 

the FS from time varying aggregate interference from other 

radiocommunication services sharing the FS band on a coprimary basis. They have issued recommendations relative to 

specific frequency bands for both long- and short-term 

interference. In the studies NASA is performing, the UAES 

transmit and FS receive characteristics are the primary 

parameters used in the analysis. 

UA Earth Station Transmit and Fixed Service 

Receive Parameters 

The UA earth station transmit parameters that are applied to 

sharing studies for AI 1.5 are being developed through WP5B. 

The parameter values under consideration can be found in 

Annex 25 of (Ref. 3). Antenna parameters and transmit 

powers have been specified for antenna diameters of 0.45, 0.8, 

and 1.25 m for both the 14.0 to 14.5 GHz and 27.5 to 

29.5 GHz bands. The FS parameters applied to the sharing are 

derived primarily from (Ref. 4) for the 14.0 to 14.5 GHz and 

27.5 to 29.5 GHz bands. 

Distribution of UA 

The number and distribution of UA are defined in 

Reference 1. The UA density projections for the 2030 timeframe based on estimated UAS usage rates in both the 

commercial and government sectors is described in Table 2. 

Based on the flight scenarios that will be studied, the total of 

the medium and large UA densities are considered, since small 

UA operate only below 3000 ft. For the sharing studies, UA 

are randomly distributed in an area bounded by the radio 

horizon relative to an FS receiver using the relative densities 

shown in Table 2. 

Fuselage Attenuation 

The fuselage of the UA can provide significant attenuation 

of the signal between the earth station mounted on the top of 

the UA and systems on the ground. Figure 2 depicts the 

calculated fuselage attenuation factored into the analysis as a 

function of elevation angle of the UAES antenna and 

frequency. 

TABLE 2.—UAS TRAFFIC DISTRIBUTION 

Type Altitude UA/km2 UA/10,000 km2 UA/Spot beam UA/Regional coverage beam 

Medium 300 to 5500 m 0.000195 1.950 93 1515 

Large !5500 m 0.000044 0.440 21 341 

Figure 2.—Example off-axis attenuation plot due to the fuselage of the aircraft 

(measurements were made at 14.2 GHz). 

 
NASA/TM—2014-218407 5 

TABLE 3.—PROTECTION CRITERIA FOR THE FIXED SERVICE IN THE 14.0 TO 14.5 AND 27.5 TO 29.5 GHz BANDS 

(Input to FS receiver) 

Parameter Frequency range Value ITU-R source 

document 

Comments 

I/N (Long Term) Both –10 dB F.758-5 (Ref. 4) Not to exceed for more than 

20 percent of the year 

I/N (Short Term) Ku +20 dB F.1494 (Ref. 8) Not to exceed for more than 

1u10–4 percent of the time 

I/N (Short Term) Ka +14 dB F.1495-2 (Ref. 9) Not to exceed for more than 

0.01 percent of the time in 

any month 

I/N (Short Term) Ka +18dB F.1495-2 (Ref. 9) Not to exceed for more than 

0.0003 percent of the time in 

any month 

Protection Criteria for Fixed Service Stations 

Table 3 provides the long and short term protection criteria 

for the fixed service receivers for the 14.0 to 14.5 GHz and 

27.5 to 29.5 GHz bands. 

Sharing Study Approach 

Visualyse Professional software (Ref. 5) was used to create 

models of a number of scenarios involving interference to 

FS’s from UA. These scenarios were used to analyze both 

long term and short term interference criteria at Ku-band and 

Ka-band frequencies, with small and large UA antennas, UA 

altitudes from 3000 to 19000 ft, and FS locations from 10q N 

to 70q N. For the Ku-band calculations, the antennas were 

centered at 14.4 GHz. The FS antenna has a diameter of 1.2 m, 

efficiency of 0.6, and an ITU-R F.699-7 gain rolloff (Refs. 3 

and 6). 

The Ku-band UA small antenna has a diameter of 0.45 m, 

efficiency of 0.55, an ITU-R S.580-6 rolloff, and an equivalent 

isotropic radiated power (e.i.r.p.) density of 43.78 dBW/ 

250 kHz. The Ku-band UA large antenna has a diameter of 

1.25 m, efficiency of 0.55, an ITU-R S.580-6 gain rolloff, and 

an e.i.r.p density of 57.68 dBW/250 kHz (Refs. 3 and 7). 

For the Ka-band calculations, the antennas were centered at 

28.5 GHz. The FS antenna has a diameter of 0.3 m, efficiency 

of 0.6, and an ITU-R F.699-7 gain rolloff (Refs. 3 and 6). The 

Ka-band UA small and large antennas have the same 

diameters, efficiency, and rolloff as the Ku-band antennas. 

The Ka-band UA small antenna has an e.i.r.p. density of 

42.38 dBW/250 kHz and the Ka-band UA large antenna has 

an e.i.r.p. density of 48.08 dBW/250 kHz. 

Long Term Interference Criteria 

For the long term interference criterion, we use guidance 

from Table 4 of (Ref. 4) which recommends that the aggregate 

interference to noise ratio I/N be less than –10 dB for 

frequencies above 3 GHz. In the Visualyse calculations, we 

placed the FS at specific locations and populated the 

surrounding airspace with 300,000 randomly located UA’s. 

The FS antenna azimuthal and elevation angles were randomly 

assigned values from –180 to +180q and –5 to +5q, 

respectively. The expected percentage of time that I/N exceeds 

–10 dB, P, is then 

 P = QRAȡ (1) 

where Q is the percentage of the locations that contributed an 

I/N of greater than –10 dB to the FS; R is the probability ratio 

that a UA is transmitting in a channel that is within the FS 

bandwidth (for the Ku-band cases, the FS has a maximum 

bandwidth of 28 MHz, thus the probability that a UA is 

transmitting at a channel that is within the FS bandwidth is 

28/500 = 0.056; for the Ka-band cases, the FS maximum 

bandwidth is 112 MHz, thus the probability that a UA is 

transmitting at a channel that is within the FS bandwidth is 

112/2000 = 0.056, the same as for Ku-band), A is the airspace 

area; and ȡ is the projected UA traffic density from Table 2, 

2.39 UA/10,000 sq km. 

UA altitudes of 3000 and 19000 ft and UA small and large 

antennas were modeled with FS locations at 10, 40, and 70q N. 

The results for the Ku-band cases are shown in Table 4 and for 

the Ka-band cases in Table 5. In all the Ku-band cases, the 

percentage of time that I/N is over the threshold of –10 dB is 

less than 0.8 percent, far below the protection criterion value 

of 20 percent. In all the Ka-band cases except two, there were 

no instances of I/N over the threshold. The only cases with I/N 

instances over the threshold were the small and large UA 

antenna cases for an altitude of 3000 ft at 70q N. But in these 

two cases the percentage of time over the threshold was only 

0.02 percent, also far below the protection criterion value of 

20 percent. 
NASA/TM—2014-218407 6 

TABLE 4.—PERCENTAGE OF TIME I/N IS WORSE THAN –10 dB FOR FS WITH BANDWIDTH OF 

28 MHz WITH FEEDER LOSS = –6 dB AND POLARIZATION LOSS = 0 FOR KU-BAND 

[Also shown are the worst values of I/N.] 

Case Altitude, 

ft 

Antenna size Latitude, 

degrees 

Percentage time over interference 

threshold, 

percent 

Worst I/N, 

dB 

1 3000 Small 10 0.13 4.07 

2 3000 Large 10 0.31 9.07 

3 3000 Small 40 0.15 4.35 

4 3000 Large 40 0.38 9.35 

5 3000 Small 70 0.24 3.21 

6 3000 Large 70 0.76 8.21 

7 19000 Small 10 0.14 –3.75 

8 19000 Large 10 0.24 1.25 

9 19000 Small 40 0.17 –2.92 

10 19000 Large 40 0.37 2.08 

11 19000 Small 70 0.41 –1.33 

12 19000 Large 70 0.72 3.67 

TABLE 5.—PERCENTAGE OF TIME I/N IS WORSE THAN –10 dB FOR FS WITH BANDWIDTH OF 

112 MHz WITH FEEDER LOSS = 0 dB AND POLARIZATION LOSS = 0 for KA-BAND 

[Also shown are the worst values of I/N.] 

Case Altitude, 

ft 

Antenna size Latitude, 

degrees 

Percentage time over interference 

threshold, 

percent 

Worst I/N, 

dB 

13 3000 Small 10 0 –12.86 

14 3000 Large 10 0 –15.96 

15 3000 Small 40 0 –10.20 

16 3000 Large 40 0 –13.30 

17 3000 Small 70 0.02 –0.83 

18 3000 Large 70 0.02 –3.93 

19 19000 Small 10 0 –23.04 

20 19000 Large 10 0 –26.14 

21 19000 Small 40 0 –18.64 

22 19000 Large 40 0 –21.74 

23 19000 Small 70 0 –17.36 

24 19000 Large 70 0 –20.46 
NASA/TM—2014-218407 7 

Short Term Interference Criteria 

The short term interference criterion at Ku-band is that I/N 

should exceed 20 dB no more than 0.0001 percent of the time 

from Table 3. For Ka-band, from Table 3 it is that “I/N should 

not exceed +14 dB for more than 0.01 percent of the time in 

any month” and “should not exceed +18 dB for more than 

0.0003 percent of the time in any month”. 

In the Visualyse calculations, we again placed the FS at 

specific locations and populated the surrounding airspace with 

300,000 randomly located UA. The Visualyse simulations 

were performed as in the Long Term Interference Criteria 

section, except that the worst possible scenario was modeled 

with the FS antenna azimuthal direction pointing northward 

and the elevation angle at the worst value between –5 to +5q

which is +5q. 

Simulations were performed at FS latitudes from 10q N to 

70q N in 100 intervals and at UA altitudes from 3000 to 

19000 ft in 1000 ft intervals. The minimum UA altitude that 

avoids exceeding the interference threshold is shown in 

Figure 3 for the large UA antenna at Ku-band and in Figure 4 

for the small UA antenna at Ku-band. For the large Ku-band 

antenna we see that the threshold altitude drops rapidly from 

18,000 ft at 70q to 7000 ft at 50q to 6000 ft at 30q and lower. 

For the small Ku-band antenna we see that the threshold 

altitude drops rapidly from 10,000 ft at 70q to 4000 ft at 50q to 

3000 ft at 10q. For the Ka-band cases, an altitude of 3000 ft 

was sufficient to stay under the interference threshold at all 

latitudes for both large and small UA antennas. 

Figure 3.—Minimum UA altitude to avoid exceeding I/N 

interference threshold for large UA antenna at Ku-band. 

Figure 4.—Minimum UA altitude to avoid exceeding I/N 

interference threshold for small UA antenna at Ku-band. 

Interpretation of Results 

The sharing studies described above, as well as 

characterization of CNPC technical and operational aspects, 

definition of performance requirements, and proposed 

regulatory changes to enable UAS CNPC over FSS satellites 

are described in draft documents being reviewed and updated 

in an iterative process through several WP5B meetings 

occurring between WRC-12 and WRC-15. In regards to the 

sharing studies in particular, agreement within WP5B on 

technical characteristics of CNPC, CNPC performance 

requirements, and appropriate protection criteria and technical 

characteristics of other systems in the bands being studies is 

still being developed. 

Changes to these various characteristics and parameters 

impacting the results of studies are expected. Hence, results 

shown here are examples and do not necessarily define the 

final results that will be approved as part of a new ITU-R 

report that will guide WRC-15 deliberations on AI 1.5. 

Nevertheless, the results serve to illustrate the sharing study 

approach and indicate the complexities of the analysis 

problem and the differences between long-term interference 

analyses and short-term interference analyses. These 

preliminary examples show that while sharing between UAES 

and FS is emerging as compatible in terms of long-term 

protection criteria, compatibility regarding the short-term 

protection criteria is still being determined. Additional 

modifications to the short-term analyses will be applied to 

refine the analyses and are expected to impact the results. At 

upcoming WP5B meetings these latest results will be 

presented and discussed by the WP5B members to determine 

where agreement on the results and their application to the 

resolution of AI 1.5 can be achieved. 
NASA/TM—2014-218407 8 

Conclusions 

For the integration of UAS into the NAS, protected aviation 

spectrum for BLOS CNPC is required. Since sufficient 

radiofrequency spectrum allocations do not currently exist, 

and there are no existing satellite systems operating in an 

existing allocation that could be applicable to BLOS CNPC, 

WRC-15 will consider the possible use of FSS satellites for 

CNPC. A number of difficult regulatory questions must be 

addressed in order to enable use of non-aviation-protected 

spectrum to be used for a protected-aviation spectrum 

application under WRC-15 AI 1.5. To support AI 1.5, studies 

of sharing between systems in several proposed FSS 

frequency bands that could be applied to CNPC is required. 

These studies look at sharing between earth stations operating 

on UA and terrestrial services operating in the same band, in 

particular FS stations. The subject of this paper is the study of 

sharing between UA earth station transmitted and FS 

receivers. 

The sharing studies involve complex analyses considering 

many parameters such as UA earth station characteristics, FS 

receive characteristics, antenna radiation patterns, relative 

signal bandwidths, expected UA densities and operational 

scenarios. Studies must consider different UA altitudes and FS 

receivers operating over a range of FS antenna elevation 

angles operating at a range of latitudes, and must address both 

short-term and long-term protection criteria. All of these 

parameters as well as other related criteria are subject to 

agreement within ITU-R WP5B which is still in process. 

This paper has provided background on the sharing studies 

supporting AI 1.5, the key technical parameters being applied, 

the analysis approach and example results. The studies will 

continue to be refined and review and discussion of the results 

by ITU-R WP5B will occur at upcoming meetings. 

References 

1. ITU-R Report M.2171 - Characteristics of unmanned 

aircraft systems and spectrum requirements to support 

their safe operation in non-segregated airspace. 

2. ITU-R Final Acts, World Radiocommunication Conference 

(WRC-12) Geneva, 23-January – 17 February 2012. 

3. ITU-R Document 5B/475E, Report on the Twelfth Meeting 

of Working Party 5B Geneva, 18-29 November 2013. 

4. ITU-R Recommendation F.758-5, System parameters and 

considerations in the development of criteria for sharing 

or compatibility between digital fixed wireless systems in 

the fixed service and systems in other services and other 

sources of interference, March 2012. 

5. http://transfinite.com/content/Professional. html. 

6. ITU-R Recommendation F.699-7, Reference radiation 

patterns for fixed wireless system antennas for use in 

coordination studies and interference assessment in the 

frequency range from 100 MHz to about 70 GHz, April 

2006. 

7. ITU-R Recommendation S.580-6, Radiation diagrams for 

use as design objectives for antennas of earth stations 

operating with geostationary satellites, January 2004. 

8. ITU-R Recommendation F.1494-0, Interference criteria to 

protect the fixed service from time varying aggregate 

interference from other services sharing the 10.7-12.75 

GHz band on a co-primary basis, May 2000. 

9. ITU-R Recommendation F.1495-2, Interference criteria to 

protect the fixed service from time varying aggregate 

interference from other radiocommunication services 

sharing the 17.7-19.3 GHz band on a co-primary basis, 

March 2012.