Interference Analysis Between UWB Devices and Aeronautical Radio Services

-1-

ACP/WGF12 - WP/09

Agenda Item 4:Ultra Wide Band (UWB)

Interference analysis between uwb devices and aeronautical radio services

(presented by the Secretariat)

1Introduction

ITU-R Task Group 1/8 is currently developing material for Section 5 of the preliminary new report on ultra-wideband (UWB) compatibility. It is intended that the next meeting of TG 1/8, which is currently planned for November 2004, would complete the draft report. In order to progress the preparation of the compatibility analysis with different radio services, a template for summary of the analysis was developed. The interference analysis with aeronautical systems, as presented in this contribution, were conducted and formatted according to the suggested template.

In this contribution three interference analysis between UWB transmitters and aeronautical systems (ILS localizer, DME and GPS) are examined.

2Required protection criteria

Annex 10 to the Convention on International Civil Aviation does not specify all receiver interference immunity characteristics necessary to fully evaluate the potential interference to aeronautical radio systems from emissions of UWB devices. It should be noted that UWB systems are not standardized. Different UWB system parameters may have an impact on the transmitted waveform and thus different interference signal characteristics may affect the operation of aeronautical radio systems in different ways. The maximum value of UWB interference signal power that still allows the victim receiver to meet its performance requirements should be derived by measurements.

For this analytical approach the protection requirements were taken from Annex 10, RTCA DO-189 and RTCA DO-233.

3Interference assessment

3.1Single interfering UWB device analysis

3.1.1Maximum tolerable UWB emission limit

The interference level at the victim receiver is a function of the gains and losses the interference signal will incur between the source and the receiver. Maximum tolerable UWB emission limit for given separation distances/heights can be derived from the following equation 1:

/ (1)

where:

PUWB_tolMaximum tolerable UWB emission limit per reference bandwidth (dBm/MHz)

PRX_tolVictim receiver total tolerable UWB interference level at isotropic antenna port per reference bandwidth (dBm/MHz)

ffrequency (MHz)

ddistance/height (km)

3.1.2Minimum required separation distance for a given UWB emission limit

The minimum geographical separation between a single UWB device and the aeronautical receiver is derived from the required propagation loss between UWB transmitter and victim receiver.

/ (2)

where:

Lreqrequired propagation loss (dB)

EIRPUWB emission limit (dBm/MHz)

PRX_tolvictim receiver total tolerable UWB interference level at isotropic antenna port per reference bandwidth (dBm/MHz)

If the required propagation loss is known then equation 3 may be used to calculate the minimum required distance between a single UWB device and the victim receiver:

/ (3)

where:

dminminimum required separation distance (km)

Lreqrequired propagation loss (dB)

ffrequency (MHz)

3.2Aggregate interference analysis

In highly populated areas, aircraft in flight may be exposed to interfering signals transmitted from a large number of emitters on the ground at the same time. This leads to the issue of potential aggregate interference.

For the estimation of aggregate interference power levels produced by a large number of UWB devices two methodologies are currently proposed.

Both methodologies make a number of fundamental assumptions:

a)that all emitters are uniformly distributed in a circular area below the victim receiver;

b)that all emitters radiating on the same frequency, the same power levels and using isotropic antennas with omni-directional radiation pattern;

c)that free space propagation are assumed; and

d)that all single emitters are statistically independent and the power contribution of all single emitters can be added arithmetically.

Figure 1

The cumulative methodology

3.2.1NTIA airborne aggregate model

The average aggregate interference A in W per unit bandwidth can be written as:

/ (4)

where:

Aaverage aggregate interference power in (watts per unit bandwidth)

eirpaverage UWB device effective isotropically radiated power (watts per unit bandwidth)

wavelength (meters)

Grvictim receiver antenna gain

average density of UWB emitters (emitters per square-meter)

Reeffective earth radius (meters)[1]

Rradius of the observed zone or the radio horizon (meters)

hheight of the receive antenna above the ground (meters)

H=Re(1-cos(R/Re).

3.2.2ICAO cumulative model

/ (5)

where:

pcumreceived cumulative interference power per reference bandwidth in W

awaperture of an isotropic antenna in m2

wavelength in m

ndensity of emitters per m2

piisotropically radiated power from a single emitter per reference bandwidth in W

haircraft height in meters

rmininner radius of the observed zone

rmaxouter radius of the observed zone

A comparative analysis has shown that both models deliver similar results. The ICAO model provides more flexibility to define the area of the observed zone, whereas the NTIA model might be easier to use because no integration operation has to be performed.

3.2.3Calculation of maximum tolerable UWB emitter density

Equation 6 can be used to calculate the UWB emitter density ρmax that will generate an aggregate interference power level equal to the victim receiver’s total tolerable interference level PRX_tol at its isotropic antenna port.

/ (6)

3.2.4Calculation of maximum UWB single device emission limit

The maximum UWB single device emission limit for given receiver height h and UWB emitter density ρ can be derived when solving equation 6 for the effective isotropically radiated power eirp.

/ (7)

4UWB emission limits

TG 1/8 suggested UWB emission limits (see Table 1) to be used for interference analysis with radiocommunication services.

Table 1

UWB emission limits:
FCC emission limits and Slope emission mask

FCC and Slope mask emission limits
Frequency
(GHz) / Indoor slope mask
emission limits / Outdoor slope mask
emission limits / Indoor FCC
emission limits / Outdoor FCC
emission limits
0.089 / -185.45 / -195.45 / -42.5 / -42.5
0.2 / -154.86 / -164.86 / -42.5 / -42.5
0.216 / -151.95 / -161.95 / -42.5 / -42.5
0.217 / -151.78 / -161.78 / -40 / -40
0.5 / -120.24 / -130.24 / -40 / -40
0.8 / -102.48 / -112.48 / -40 / -40
0.96 / -95.59 / -105.59 / -40 / -40
0.961 / -95.55 / -105.55 / -75.3 / -75.3
1.47 / -79.50 / -89.50 / -75.3 / -75.3
1.61 / -76.05 / -86.05 / -75.3 / -75.3
1.611 / -76.03 / -86.03 / -53.3 / -63.3
1.99 / -68.05 / -78.05 / -53.3 / -63.3
1.991 / -68.03 / -78.03 / -51.3 / -61.3
3.1 / -51.3 / -61.3 / -51.3 / -61.3
3.101 / -41.3 / -41.3 / -41.3 / -41.3
10.6 / -41.3 / -41.3 / -41.3 / -41.3
10.601 / -51.30 / -61.30 / -51.3 / -51.3
30 / -90.61 / -100.61 / -51.3 / -51.3
50 / -109.91 / -119.91 / -51.3 / -51.3
100 / -136.10 / -146.10 / -51.3 / -51.3
400 / -188.48 / -198.48 / -51.3 / -51.3

Graphical representations of the FCC and the Slope Masks (indoor and outdoor) are given in figure2 below.

Figure 2

UWB emission limits

5Recommendation

ACP WG/F is requested to:

a)review the recommended methodologies for interference analysis between UWB devices and aeronautical radio services;

b)review the suggested protection requirements for ILS LLZ, DME and GPS to be used for an analytical approach; and

c)develop material to be presented to the forthcoming meeting of ITU-R TG 1/8.

Annex 1

Instrument Landing System – Localizer (ILS LLZ)

Summary of compatibility studies

1Aeronautical Radionavigation Service

1.1Application: Instrument Landing System – Localizer (ILS)

The instrument landing system (ILS) is one of the ICAO standard precision approach and landing systems. It provides precision guidance to an aircraft during the final stages of the approach. The signals can either be interpreted by the pilot from the instruments or be input directly into the autopilot and flight management system. ILS performance is divided into three categories depending on the reliability, integrity and quality of guidance, with Category III having the strictest requirements. An ILS comprises the following elements:

a)the localizer, operating in the frequency band from 108 to 112 MHz, providing azimuth guidance to a typical maximum range of 46.3 km (25 NM) from the runway threshold;

b)the glide path, operating in the frequency band from 328.6 to 335.4 MHz, providing elevation guidance to a typical maximum range of 18.5 km (10 NM) from the runway threshold; and

c)the marker beacons operating on the frequency of 75 MHz, providing position information at specific distances from the runway threshold.

1.2Frequency band:

108 – 117.975 MHz

1.3Protection requirements:

Total tolerable interference level at isotropic antenna port

Parameter / Value / Unit / Remarks
Minimum power flux density limit within ILS LLZ service area / -114 / dB(W/m2) / ICAO Annex 10
Received power at isotropic antenna port / -116.3 / dBW / Reference frequency: 110 MHz

Signal-to-interference ratio / 46 / dB / RTCA DO-233 interference type 1
Aeronautical safety factor / 6 / dB
Single-to-multiple interference factor / 10 / dB / If there is a potential for other than interference sources at the same time, an allowance should be made for the aggregate interference
Total tolerable interference level at isotropic antenna port per IF bandwidth / -178.3 / dB(W/40kHz) / Receiver IF bandwidth 40 kHz
Bandwidth correction factor / 14 / dB /
assumed ILS LLZ BIF = 40 kHz
Total tolerable UWB interference level at isotropic antenna port per reference bandwidth / -164.3 / dB(W/MHz) / Reference bandwidth 1 MHz

2Interference scenarios and methodology

2.1UWB characteristics

Parameter / Value / Unit / Remarks
FCC indoor emission limit / -42.5 / dBm/MHz / 110 MHz
FCC outdoor emission limit / -42.5 / dBm/MHz / 110 MHz
Slope mask indoor emission limit / -177.4 / dBm/MHz / 110 MHz
Slope mask outdoor emission limit / -187.4 / dBm/MHz / 110 MHz
Activity factor / 100 / %

2.2Methodology for single UWB transmitter

The methodology as described in document PDNR ITU-R SM.[UWB.COMP], section A2.2.1. has been used. The propagation loss between transmitting and receiving antennas has been derived from free-space propagation.

2.3Methodology for multiple UWB transmitters

For the calculation of the cumulative interference power generated by multiple UWB devices the NTIA airborne aggregate model, as given in document PDNR ITU-R SM.[UWB.COMP], section A2.3 has been used.

3Results of theoretical compatibility studies

3.1Single interfering UWB device analysis:

3.1.1Tolerable UWB emission limit for different victim receiver heights

Tolerable UWB emission limit for a single device at 110 MHz, dBm/MHz
RX height
70 ft
(21m) / RX height
100 ft
(30m) / RX height
1000 ft
(305m) / RX height
3000 ft
(915m) / RX height
6000 ft
(1829m)
-94.6 / -91.5 / -71.4 / -61.8 / -55.8

3.1.2Required separation distances for given UWB emission limits

UWB FCC indoor emission limit / FCC limit
-42.5 dBm/MHz at 110 MHz
Required separation distance, m / 8484
UWB FCC outdoor emission limit / FCC limit
-42.5 dBm/MHz at 110 MHz
Required separation distance, m / 8484
UWB slope indoor emission limit / Slope mask
-177.4 dBm/MHz at 110 MHz
Required separation distance, m / 0
UWB slope outdoor emission limit / Slope mask
-187.4 dBm/MHz at 110 MHz
Required separation distance, m / 0

3.2Aggregate interference analysis:

3.2.1Maximum tolerable UWB emitter density for given UWB single device emission limits and victim receiver heights

UWB single device emission limit / Tolerable UWB emitter density per km2
RX height
70 ft
(21m) / RX height
100 ft
(30m) / RX height
1000 ft
(305m) / RX height
3000 ft
(915m) / RX height
6000 ft
(1829m)
FCC in-door at 110MHz
-42.5 dBm/MHz / 0.0003 / 0.0003 / 0.0004 / 0.0004 / 0.0005
FCC out-door at 110MHz
-42.5 dBm/MHz / 0.0003 / 0.0003 / 0.0004 / 0.0004 / 0.0005
Slope in-door at 110MHz
-177.4 dBm/MHz / 1.01·1010 / 1.04·1010 / 1.26·1010 / 1.4·1010 / 1.51·1010
Slope out-door at 110MHz
-187.4 dBm/MHz / 1.01·1011 / 1.04·1011 / 1.26·1011 / 1.4·1011 / 1.51·1011

3.2.2Maximum UWB single device emission limit for given emitter density and victim receiver height

Emitter density
(emitters/km2) / Tolerable UWB emission limit for a single device at 110 MHz, dBm/MHz
RX height
70 ft
(21m) / RX height
100 ft
(30m) / RX height
1000 ft
(305m) / RX height
3000 ft
(915m) / RX height
6000 ft
(1829m)
1 / -77.3 / -77.2 / -76.4 / -75.9 / -75.6
10 / -87.3 / -87.2 / -86.4 / -85.9 / -85.6
100 / -97.3 / -97.2 / -96.4 / -95.9 / -95.6
1000 / -107.3 / -107.2 / -106.4 / -105.9 / -105.6
10000 / -117.3 / -117.2 / -116.4 / -115.9 / -115.6
100000 / -127.3 / -127.2 / -126.4 / -125.9 / -125.6
1000000 / -137.3 / -137.2 / -136.4 / -135.9 / -135.6

4Conclusions

tbd

Annex 2

Distance Measuring Equipment (DME)

Summary of compatibility studies

1Aeronautical Radionavigation Service

1.1Application: Distance Measuring Equipment (DME)

DME is the ICAO standard system for the determination of the distance between an aircraft and a ground-based DME beacon within radio line of sight, using pulse techniques and time measurement. DME/N is the standard system used for en-route and terminal navigation. It can be co-located with VHF omni-directional radio range (VOR) enabling the aircraft’s position to be determined through a measurement of its bearing and the distance relative to the VOR/DME. Alternatively, the aircraft’s position can be determined through measurement of the distances from three or more DMEs. DME/P is a precision version of DME with enhanced precision measurement capability which is used in conjunction with MLS to provide accurate distance to touch down.

1.2Frequency band:

960 – 1215 MHz

1.3Protection requirements:

Total tolerable interference level at isotropic antenna port

Parameter / Value / Unit / Remarks
DME interference threshold at antenna port / -129 / dB(W) / This value is based on a –129dBW CW interference threshold specified for international DME systems used by civil aviation. Measurement has demonstrated that an noise-like RNSS signal spread over 1MHz would have the same effect as a CW signal on DME performance. The applicability of this value to UWB signals should be verified by measurements.
Antenna gain towards interference source / 0 / dB / The difference in antenna gain towards the interference signal
Single-to-multiple interference factor / 10 / dB / If there is a potential for other than interference sources at the same time, an allowance should be made for the aggregate interference. Since UWB is not considered as a radio service a 10% allowance is made.
Aeronautical safety factor / 6 / dB
Total tolerable UWB interference level at isotropic antenna port / -145 / dB(W/MHz)

2Interference scenarios and methodology

2.1UWB characteristics

Parameter / Value / Unit / Remarks
FCC indoor emission limit / -75.3 / dBm/MHz / 960 – 1215 MHz
FCC outdoor emission limit / -75.3 / dBm/MHz / 960 – 1215 MHz
Slope mask indoor emission limit / -95.6 / dBm/MHz / 960 MHz
-90.4 / dBm/MHz / 1100 MHz
-86.7 / dBm/MHz / 1215 MHz
Slope mask outdoor emission limit / -105.6 / dBm/MHz / 960 MHz
-100.4 / dBm/MHz / 1100 MHz
-96.7 / dBm/MHz / 1215 MHz
Activity factor / 100 / %

2.2Methodology for single UWB transmitter

2.3Methodology for multiple UWB transmitters

3Results of theoretical compatibility studies

3.1Single interfering UWB device analysis:

3.1.1Tolerable UWB emission limit for different victim receiver heights

Tolerable UWB emission limit for a single device at 1100 MHz, dBm/MHz
RX height
70 ft
(21m) / RX height
100 ft
(30m) / RX height
1000 ft
(305m) / RX height
10000 ft
(3048m) / RX height
45000 ft
(13716m)
-55.3 / -52.3 / -32.1 / -12.1 / 1

3.1.2Required separation distances for given UWB emission limits

UWB FCC indoor emission limit / FCC limit
-75.3 dBm/MHz at 960 MHz / FCC limit
-75.3 dBm/MHz at 1100 MHz / FCC limit
-75.3 dBm/MHz at 1215 MHz
Required separation distance, m / 24 / 21 / 19
UWB FCC outdoor emission limit / FCC limit
-75.3 dBm/MHz at 960 MHz / FCC limit
-75.3 dBm/MHz at 1100 MHz / FCC limit
-75.3 dBm/MHz at 1215 MHz
Required separation distance, m / 24 / 21 / 19
UWB slope mask indoor emission limit / Slope mask
-95.6 dBm/MHz at 960 MHz / Slope mask
-90.4 dBm/MHz at 1100 MHz / Slope mask
-86.7 dBm/MHz at 1215 MHz
Required separation distance, m / 0.2 / 0.3 / 0.5
UWB slope mask outdoor emission limit / Slope mask
-105.6 dBm/MHz at 960 MHz / Slope mask
-100.4 dBm/MHz at 1100 MHz / Slope mask
-96.7 dBm/MHz at 1215 MHz
Required separation distance, m / 0.06 / 0.1 / 0.2

3.2Aggregate interference analysis:

3.2.1Maximum tolerable UWB emitter density for given UWB single device emission limits and victim receiver heights

UWB single device emission limit / Tolerable UWB emitter density per km2
RX height
70 ft
(21m) / RX height
100 ft
(30m) / RX height
1000 ft
(305m) / RX height
10000 ft
(3048m) / RX height
45000 ft
(13716m)
FCC in-door at 960 MHz
-75.3 dBm/MHz / 4054 / 4164 / 5047 / 6396 / 7755
FCC in-door at 1100 MHz
-75.3 dBm/MHz / 5323 / 5467 / 6627 / 8398 / 10182
FCC in-door at 1215 MHz
-75.3 dBm/MHz / 6494 / 6696 / 8085 / 10245 / 12422
FCC out-door at 960 MHz
-75.3 dBm/MHz / 4054 / 4164 / 5047 / 6396 / 7755
FCC out-door at 1100 MHz
-75.3 dBm/MHz / 5323 / 5467 / 6627 / 8398 / 10182
FCC out-door at 1215 MHz
-75.3 dBm/MHz / 6494 / 6696 / 8085 / 10245 / 12422
Slope in-door at 960 MHz
-95.6 dBm/MHz / 434456 / 446155 / 540861 / 685399 / 831005
Slope in-door at 1100 MHz
-90.4 dBm/MHz / 172261 / 176900 / 214451 / 271760 / 329493
Slope in-door at 1215 MHz
-86.7 dBm/MHz / 89651 / 92065 / 111608 / 141433 / 171480
Slope out-door at 960 MHz
-105.6 dBm/MHz / 4344560 / 4461550 / 5408618 / 6853991 / 8310059
Slope out-door at 1100 MHz
-100.4 dBm/MHz / 1722617 / 1769003 / 2144515 / 2717605 / 3294936
Slope out-door at 1215 MHz
-96.7 dBm/MHz / 559687 / 574759 / 696764 / 882965 / 1070542

3.2.2Maximum UWB single device emission limit for given emitter density and victim receiver height

Emitter density
(emitters/km2) / Tolerable UWB emission limit for a single device at 1100 MHz, dBm/MHz
RX height
70 ft
(21m) / RX height
100 ft
(30m) / RX height
1000 ft
(305m) / RX height
10000 ft
(3048m) / RX height
45000 ft
(13716m)
1 / -38.0 / -37.9 / -37.1 / -36.1 / -35.2
10 / -48.0 / -47.9 / -47.1 / -46.1 / -45.2
100 / -58.0 / -57.9 / -57.1 / -56.1 / -55.2
1000 / -68.0 / -67.9 / -67.1 / -66.1 / -65.2
10000 / -78.0 / -77.9 / -77.1 / -76.1 / -75.2
100000 / -88.0 / -87.9 / -87.1 / -86.1 / -85.2
1000000 / -98.0 / -97.9 / -97.1 / -96.1 / -95.2

4Conclusions

tbd

Annex 3

Global Positioning System (GPS) of the Global Navigation Satellite System (GNSS)

Summary of compatibility studies

1Radionavigation Satellite Service

1.1Application: Global Positioning System (GPS) of the Global Navigation Satellite System (GNSS)

The GNSS is a worldwide position and time determination system, which includes one or more satellite constellations, aircraft receivers, and system integrity monitoring, augmented as necessary to support the required navigational performance for the actual phase of aircraft operation. The satellite navigation systems in operation are the Global Positioning System (GPS) of the United States and the Global Orbiting Navigation Satellite System (GLONASS) of the Russian Federation. Both systems were offered to ICAO as a means to support the evolutionary development of GNSS.

The GPS consists of 24 satellite positions with four satellite positions in each of six 55° inclined equally spaced orbital planes. Each satellite will transmit the same two frequencies for navigational signals. These navigational signals are modulated with a predetermined bit stream, containing coded ephemeris data and time, and having a sufficient bandwidth to produce the necessary navigation precision without recourse to two-way transmission or Doppler integration. The system will provide accurate position determination in three dimensions anywhere on or near the surface of the Earth.

1.2Frequency band:

1559 – 1610 MHz

L1 carrier frequency 1575.42 MHz

1.3Protection requirements:

Total tolerable interference level at victim receiver’s isotropic antenna port

Parameter / Value / Unit / Remarks
Receiver aggregate wideband interference threshold in acquisition mode at antenna port / -146.5 / dB(W/MHz) / Receiver aggregate wideband interference threshold in acquisition mode as given in ICAO Annex 10 and ITU-R M.1477. This value is considered to be applicable for noise like signals only. For this analysis the UWB signal is considered to be noise like. This value is taken as the maximum value of UWB interference signal power that still allows the receiver to meet its performance requirements.
Antenna gain towards interference source / 0 / dB / Victim receiver antenna gain towards the interfering UWB signal
Single-to-multiple interference factor / 10 / dB / If there is a potential for other than interference sources at the same time, an allowance should be made for the aggregate interference. Since UWB is not considered as a radio service a 10% allowance is made.
Aeronautical safety factor / 6 / dB
Total tolerable UWB interference level at isotropic antenna port / -162.5 / dB(W/MHz)

2Interference scenarios and methodology

2.1UWB characteristics

Parameter / Value / Unit / Remarks
FCC indoor emission limit / -75.3 / dBm/MHz / 1575 MHz
FCC outdoor emission limit / -75.3 / dBm/MHz / 1575 MHz
Slope mask indoor emission limit / -76.9 / dBm/MHz / 1575 MHz
Slope mask outdoor emission limit / -86.9 / dBm/MHz / 1575 MHz
Activity factor / 100 / %

2.2Methodology for single UWB transmitter