B-AMC Interference Analysis and Spectrum Requirements

Transcription

1 REPORT D4 B-AMC Interference Analysis and Spectrum Requirements PROJECT TITLE: BROADBAND AERONAUTICAL MULTI-CARRIER COMMUNICATIONS SYSTEM PROJECT ACRONYM: B-AMC PROJECT CO-ORDINATOR: FREQUENTIS AG FRQ A PRINCIPAL CONTRACTORS: DEUTSCHES ZENTRUM FÜR LUFT UND RAUMFAHRT E.V. DLR D PARIS LODRON UNIVERSITAET SALZBURG USG A MILERIDGE LIMITED MIL UK DOCUMENT IDENTIFIER: D4 ISSUE: 1.1 ISSUE DATE: AUTHOR: DISSEMINATION STATUS: DOCUMENT REF: FREQUENTIS PUBLIC CIEA15_EN503.11

2 History Chart Issue Date Changed Page (s) Cause of Change Implemented by All sections New document Frequentis All sections Completion of missing sections Frequentis Review comments from ECTL and FAA incorporated All sections Comments and finding from Close-Down meeting incorporated Frequentis Authorisation No. Action Name Signature Date 1 Prepared M. Sajatovic (FRQ) Approved J. Prinz (FRQ) Released C. Rihacek (FRQ) The information in this document is subject to change without notice. All rights reserved. No part of the document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the written permission of FREQUENTIS AG. Company or product names mentioned in this document may be trademarks or registered trademarks of their respective companies. Page: I

3 Contents 1. Executive Summary Introduction Study Background Specific Context Objectives of Work Package Characteristics of L-band Transmitters TX Parameters DME airborne TX TX Spectral Characteristics TX EIRP and Duty Cycle DME ground TX TX Spectral Characteristics TX EIRP and Duty Cycle SSR airborne TX TX Spectral Characteristics ACAS Interrogator TX EIRP ACAS TX SSR ground TX TX Spectral Characteristics TX EIRP UMTS900 mobile TX TX Spectral Characteristics TX EIRP UMTS900 BS TX TX Spectral Characteristics TX EIRP GSM900 mobile TX TX Spectral Characteristics Page: II

4 TX EIRP GSM900 BS TX TX Spectral Characteristics TX EIRP JTIDS/MIDS TX TX Spectral Characteristics Time Domain Characteristics TX EIRP and Duty Cycle UAT Airborne TX TX Spectral Characteristics TX EIRP UAT Ground TX TX Spectral Characteristics TX EIRP Characteristics of L-band Receivers DME airborne RX RX Selectivity RX Protection Criteria DME ground RX RX Selectivity RX Protection Criteria SSR airborne RX RX Selectivity RX Protection Criteria SSR ground RX RX Selectivity RX Protection Criteria UMTS900 mobile RX RX Selectivity RX Protection Criteria UMTS900 BS RX RX Selectivity RX Protection Criteria GSM900 mobile RX Page: III

5 RX Selectivity RX Protection Criteria GSM900 BS RX RX Selectivity RX Protection Criteria JTIDS/MIDS RX UAT Airborne RX RX Selectivity RX Protection Criteria UAT Ground RX RX Selectivity RX Protection Criteria L-Band RX Parameters Characteristics of L-band Antennas Antenna Orientation Airborne Aeronautical L-band Antennas Ground Aeronautical L-band Antennas L-band UMTS and GSM Antennas L-band Antennas B-AMC RX as an Interference Victim Introduction B-AMC Ground RX RX Selectivity RX Protection Criteria B-AMC Airborne RX RX Selectivity RX Protection Criteria Method Used for DME Interference Investigations Effect of Over-Sampling Benefits from RX Windowing Recommendations Scenario Definition Scenario 1: Airborne TXs! Airborne B-AMC RX (same A/C) Page: IV

6 6.7. Scenario 2: Airborne TXs! Airborne B-AMC RX (Other A/C) DME_A TX! B-AMC_A RX MIDS_A TX! B-AMC_A RX SSR_A TX! B-AMC_A RX UAT_A TX! B-AMC_A RX Scenario 3: Ground TXs! Airborne B-AMC RX DME_G TX! B-AMC_A RX MIDS_G TX! B-AMC_A RX SSR_G TX! B-AMC_A RX UAT_G TX! B-AMC_A RX GSM/UMTS_BS TX! B-AMC_A RX GSM/UMTS_Mobile Equipment TX! B-AMC_A RX Scenario 4: Airborne TXs! Ground B-AMC RX DME_A TX! B-AMC_G RX MIDS_A TX! B-AMC_G RX SSR_A TX! B-AMC_G RX UAT_A TX! B-AMC_G RX Scenario 5: Ground TXs! Ground B-AMC RX B-AMC TX as an Interference Source Introduction B-AMC Ground TX TX Spectral Characteristics Side-lobe Suppression Phase Noise Third-order IMD Distortion Composite TX Spectral Mask Spurious Signals TX EIRP B-AMC Airborne TX TX Spectral Characteristics TX EIRP Method Used for Interference Investigations Scenario Definition Scenario 1: Airborne B-AMC TX > Airborne RXs/Own Aircraft Page: V

7 7.7. Scenario 2: Airborne B-AMC TX > Airborne RXs/Close Aircraft B-AMC_A TX > DME_A/SSR_A/UAT_A RX Scenario 2 Conclusion Scenario 3: Ground B-AMC TX > Airborne RXs B-AMC_G TX > DME_A/SSR_A/UAT_A RX Scenario 3 Conclusion Scenario 3a: Airborne B-AMC TX > Ground RXs B-AMC_A TX > DME_G/UAT_G RX (3a_1) Scenario 3a_1 Conclusion B-AMC_A TX > SSR_G RX (3a_2) Scenario 3a_2 Conclusion B-AMC_A TX > UMTS_M/GSM_M RX (3a_3) Scenario 3a_3 Conclusion B-AMC_A TX > UMTS_G/GSM_G RX (3a_4) Scenario 3a_4 Conclusion Scenario 4: Ground B-AMC TX > Ground RXs B-AMC_G TX > DME_G/UAT_G RX (4_1) Scenario 4_1 Conclusion B-AMC_G TX > UMTS_M/GSM_M RX (4_2) Scenario 4_2 Conclusion B-AMC_G TX > UMTS_G/GSM_G RX (4_3) Scenario 4_3 Conclusion B-AMC_G TX > SSR_G RX (4_4) Scenario 4_4 Conclusion Conclusions Airborne Co-site Interference Introduction B-AMC RX as Victim Receiver Introduction DME_A TX! B-AMC_A RX MIDS_A TX! B-AMC_A RX SSR_A TX! B-AMC_A RX UAT_A TX! B-AMC_A RX B-AMC TX as Interfering Transmitter Page: VI

8 B-AMC_A TX! DME_A RX B-AMC_A TX! UAT_A RX B-AMC_A TX! SSR_A RX B-AMC TX RL Duty-cycle B-AMC RF Issues B-AMC Receiver RF Front-end B-AMC Transmitter RF Front-end B-AMC Duplexer B-AMC Spectrum Requirements Total Spectrum Requirements A/G Mode Total Spectrum Requirements A/A Mode References Abbreviations Illustrations Figure 3-1: DME pulse envelope Figure 3-2: Airborne DME Transmitter Spectrum (0.5 MHz Measurement BW) Figure 3-3: Ground DME Transmitter Spectrum (0.5 MHz Measurement BW) Figure 3-4: Airborne SSR Transponder Spectral Mask Figure 3-5: Ground SSR Interrogator Spectral Mask Figure 3-6: UMTS Mobile TX Spectral Mask Figure 3-7: UMTS BS Spectrum Emission Mask Figure 3-8: GSM900 Mobile TX Spectral Mask Figure 3-9: GSM900 BS TX Spectral Mask Figure 3-10: JTIDS/MIDS TX Spectral Mask Figure 3-11: Measured JTIDS/MIDS TX Spectrum Figure 3-12: UAT TX Spectral Mask Figure 4-1: Selectivity of DME 442 and KN62A DME Receivers Figure 4-2: SSR_A RX Selectivity (assumed) Page: VII

9 Figure 4-3: SSR_G RX Selectivity (assumed) Figure 4-4: UMTS_M/UMTS_G RX Selectivity (assumed) Figure 4-5: UMTS_M/UMTS_G RX Selectivity (assumed) Figure 4-6: GSM_M/GSM_G RX Selectivity (assumed) Figure 4-7: GSM_M/GSM_G RX Selectivity (assumed) Figure 4-8: UAT_A/UAT_G RX Selectivity Figure 5-1: Elevation Angles for Airborne (α) and Ground (φ) Antennas Figure 5-2: Vertical Patterns of Airborne DME and MIDS Antennas Figure 5-3: SSR Radar Ground Antenna Vertical Pattern Figure 5-4: DME and TACAN Ground Antenna Vertical Pattern Figure 5-5: Vertical Patterns of BS UMTS Antennas Figure 6-1: Assumed B-AMC RX IF selectivity Figure 6-2: BER vs. Eb/N0 for different channels without DME interference Figure 6-3: MATLAB Simulation Chain Figure 6-4: DME pulse pair generated in MATLAB Figure 6-5: Spectrum of one DME interferer at 0.5 MHz offset Figure 6-6: Figure 6-7: Spectrum of one DME interferer at 0.5 MHz offset, 2-times over-sampling6-10 Spectrum of four DME interferers with four-times over-sampling and RC filter Figure 6-8: Spectrum of one DME interferer, first pulse partly cut off Figure 6-9: Principle of receiver windowing Figure 6-10: Pulse pair in time domain after RX windowing Figure 6-11: Interference Scenarios with B-AMC RX as Victim Figure 6-12: Spectrum of DME Interference Signal in Scenario Figure 6-13: Spectrum of DME Interference Signal in Scenario 2, Zoom Figure 6-14: Spectrum of interference signal in scenario 3 (a) Figure 6-15: Spectrum of interference signal in scenario 3 (b) Figure 7-1: Side-lobe Suppression, 48 Carriers, 2*2 CC, RC Windowing Figure 7-2: B-AMC TX Spectral Mask Figure 7-3: Frequency Dependent Rejection in Receivers Figure 7-4: Interference Scenarios with B-AMC TX as Interferer Figure 7-5: B-AMC_A > DME_A/SSR_A/UAT_A FDR Curves Figure 7-6: B-AMC_A > DME_A/SSR_A/UAT_A Isolation Figure 7-7: B-AMC_G> DME_A/SSR_A/UAT_A FDR Curves Figure 7-8: B-AMC_G > DME_A/SSR_A/UAT_A Isolation Page: VIII

10 Figure 7-9: B-AMC_A > DME_G/UAT_G FDR Curves Figure 7-10: B-AMC_A > DME_G/UAT_G Isolation Figure 7-11: B-AMC_A > SSR_G FDR Curve Figure 7-12: B-AMC_A > SSR_G Isolation Figure 7-13: B-AMC_A > UMTS_M/GSM_M FDR Curves Figure 7-14: B-AMC_A > UMTS_M/GSM_M Isolation Figure 7-15: B-AMC_A > UMTS_M/GSM_M Isolation (APT) Figure 7-16: B-AMC_A > UMTS_G/GSM_G FDR Curves Figure 7-17: B-AMC_A > UMTS_G/GSM_G Isolation Figure 7-18: B-AMC_A > UMTS_G/GSM_G Isolation (APT) Figure 7-19: B-AMC_G > DME_G/UAT_G FDR Curves Figure 7-20: B-AMC_G > DME_G/UAT_G Isolation Figure 7-21: B-AMC_G > UMTS_M/GSM_M FDR Curves Figure 7-22: B-AMC_G > UMTS_M/GSM_M Isolation Figure 7-23: B-AMC_G > UMTS_M/GSM_M Isolation Close Distance Figure 7-24: B-AMC_G > UMTS_G/GSM_G FDR Curves Figure 7-25: B-AMC_G > UMTS_G/GSM_G Isolation Figure 7-26: B-AMC_G > UMTS_G/GSM_G Isolation Close Spacing Figure 7-27: B-AMC_G > SSR_G FDR Curve Figure 7-28: B-AMC_G > SSR_G Isolation Figure 8-1: Spectrum of DME Interference Signal in Scenario Figure 8-2: Spectrum of DME Interference Signal in Scenario 1, zoom Figure 9-1: RF Pre-selection Filters Figure 9-2: Phase Noise of L-band Sources Figure 9-3: Possible Realisation of a B-AMC Duplexer Tables Table 3-1: Parameters of L-band transmitters Table 3-2: UMTS Mobile TX Spectral Mask (P = +24 dbm) Table 3-3: UMTS BS Spectral Mask (P = +43 dbm) Table 3-4: GSM Mobile TX Spectral Mask Table 3-5: GSM BS TX Spectral Mask Table 4-1: UMTS900 MS Blocking Performance Table 4-2: UMTS900 BS Blocking Performance Page: IX

11 Table 4-3: GSM900 MS Blocking Performance Table 4-4: GSM900 BS Blocking Performance Table 4-5: UAT Airborne RX Selectivity Table 4-6: Parameters of L-band receivers Table 5-1: Parameters of L-band Antennas Table 6-1: Representative B-AMC RX IF Selectivity Table 6-2: Required Eb/N0 and S/N for achieving BER = 10-4, QPSK, R c =1/ Table 6-3: Required Power at Ground B-AMC RX Antenna Table 6-4: Required Power at Airborne B-AMC RX Antenna Table 6-5: Scenarios with B-AMC Victim RX Table 7-1: Scenarios with B-AMC TX as Interferer Table 7-2: UMTS_M/GSM_M Blocking Performance Table 7-3: UMTS_G/GSM_G Blocking Performance Table 7-4: UMTS_M/GSM_M Blocking Performance Table 7-5: UMTS_G/GSM_G Blocking Performance Table 7-6: Results of Interference Investigations with Interfering B-AMC TX Table 8-1: Phase Noise Characteristics for Different L-band Synthesisers Page: X

12 1. Executive Summary This deliverable "B-AMC Interference Analysis and Spectrum Requirements" summarizes the results of the work conducted under "WP4 - Spectrum Compatibility Issues" of the B- AMC study. In this WP, simple qualitative investigations of the mutual interference between the B AMC system and different L-band systems have been performed by using analytical methods and limited MATLAB investigations. The goal of these preliminary investigations is to determine possible effects generated by the signals of different L-band systems onto the B-AMC system receiver, as well as to estimate the maximum allowed amount of the B-AMC signal power at the input of the victim L-band receivers. More details about the B-AMC RX susceptibility to DME and MIDS/JTIDS signals are provided in deliverable "D5 Expected System Performance". Section 3 captures the parameters (TX power, EIRP, duty-cycle) of ground and airborne L-band transmitters that are relevant for the assessment of the interference upon the airborne or ground B-AMC receivers. The data are provided for airborne and ground DME, SSR and UAT transmitters, as well as for transmitters of mobile GSM/UMTS terminals and GSM/UMTS base stations operating in the 900 MHz band. The basic data derived from [FSCA-L] were supplemented by data from other sources. In order to produce common input parameter for all systems - power at TX terminals - original power values specified at different reference points in different reference documents have been re-calculated by using common assumptions about airborne and ground cable losses and antenna characteristics as proposed in Section 5. Section 4 outlines the relevant parameters (selectivity, protection criteria) of different L-band receivers to be used in interference scenarios. In all these scenarios the investigated receivers appear in the victim role. The data are provided for airborne and ground DME, SSR and UAT receivers, as well as for receivers of GSM/UMTS mobile terminals and base stations operating in the 900 MHz band. The basic data derived from [FSCA-L] were again supplemented by the data from other sources. The receiver selectivity has been explicitly specified only for DME and UAT systems. For other receivers, rectangular IF filters have been assumed, with the ultimate rejection of 70 db and a bandwidth corresponding to that specified in the reference documentation or the typical system bandwidth. If available, the receiver blocking characteristics have been captured as well. As the susceptibility parameters for different L-band systems have been defined at different reference points, these have been re-calculated to the common reference point (input terminal of the corresponding receiver) by assuming the cable losses and antenna characteristics as proposed in Section 5. Moreover, as the available susceptibility values in [FSC-L] have been defined for different kinds of known interfering signals (e.g. CW, broadband noise, DME signals), in many cases assumptions had to be made about the applicability of the particular criterion to the noise-like B-AMC interfering signal. In Section 5 the reference geometry has been proposed for the airborne and ground L-band antennas. An airborne antenna described in the related literature has been considered as representative for all airborne civil L-band systems (DME, SSR, B-AMC, UAT). Another airborne antenna type has been defined for the military MIDS system. The representative L-band ground antenna has been designed by overlying the antenna patterns for several ground L-band antennas described in literature and retaining for each elevation angle the value that would produce the maximum EIRP in that direction. A similar procedure has been applied to obtain the representative UMTS/GSM ground antenna characteristics from several available examples. As no detailed data could be Page: 1-1

13 found, an omni-directional pattern has been assumed for mobile GSM/UMTS antennas. EUROCONTROL provided the representative vertical pattern for the ground SSR antenna. The goal of the preliminary investigations in Section 6 was to determine possible effects of the DME signal-in-space onto the B-AMC system receiver. The interference situation at the B-AMC ground receiver as well as at the B-AMC airborne receiver is described, taking the RX selectivity and RX sensitivity into account. The method used for simulating and evaluating the impact of the interference from DME systems on the B-AMC receiver is presented. Several general investigations were conducted and measures for mitigating the impact of the interference and those effects, that occur during the FFT operation in the B-AMC receiver, have been proposed. Different interference scenarios for different sources of interference were defined and the impact of interference in each scenario has been evaluated in the corresponding sub-section. In scenarios, considering interference from another aircraft, the directly received DME signal power proved to be more significant than the received out-of-band DME phase noise. Additional RC filtering is proposed to increase the total B-AMC RX selectivity and reduce directly received DME interference power to the level comparable to the B-AMC receiver noise floor. Taking into account the small duty cycle of L-band systems operating on another aircraft, the relatively low probability that two aircraft will enter this scenario and also the strong FEC applied for B-AMC, the impact of this interference type is expected to be acceptable. The scenarios considering the effects on the airborne B-AMC RX caused by the interference from the ground L-band systems suggest that the centre frequency of the B-AMC FL channel should be selected such as to guarantee an offset of at least 1.5 MHz to any ground DME/TACAN station the aircraft with the B-AMC receiver might fly over. The similar requirement applies to the case where airborne DME interrogators produce interference towards the ground B-AMC RX. The investigations have shown that the B-AMC IF selectivity of 70 db may be not enough and that additional RC filtering should be considered within the B-AMC RX. The interference coming from GSM/UMTS base stations and mobile terminals is expected to be acceptably low. Section 7 deals with interference scenarios where the B-AMC ground- or airborne TX acts as an interferer, affecting the operation of receivers of other L-band systems, e.g. DME, SSR, UAT, GSM or UMTS. The spectral characteristics of the B-AMC TX has been estimated by combining contributions of the OFDM modulation side-lobes (including B-AMC-specific side-lobe reduction techniques), TX power amplifier third-order IMD products and the radiated broadband phase-noise floor. Airborne and ground B-AMC TX use in all interference scenarios the same default power value of +50 dbm. In several scenarios where the required isolation could not be achieved with that default power, reduced TX power and/or other measures (filtering) were proposed in order to mitigate the interference. Based on [B-AMC D5] results, final values of +38.5/35 dbm have been retained for B-AMC airborne/ground transmitter, respectively. As the B-AMC GS may temporarily assign all OFDM carriers to the single airborne TX, both airborne and ground B-AMC TX are assumed to transmit over the full bandwidth of 500 khz using all available OFDM carriers. Page: 1-2

14 NOTE: [B-AMC D5] results suggest that only a half of available carriers should be used on B-AMC reverse link. This would provide some additional margin on the RL. For interference investigations the Frequency Dependent Rejection (FDR) approach has been adopted. Based on the calculated FDR, the Frequency/Distance (FD) separation has been estimated, representing the required spatial distance between the interfering transmitter and a victim receiver as a function of difference between their tuned frequencies. This method is based on linear analysis, it does not consider non-linear effects in the B-AMC TX and within the victim RXs (such effects have to be assessed via measurements when the B-AMC radio hardware will become available). The results presented in this section were obtained under very conservative (worst-case) assumptions and should be regarded as a rough estimate of the worst-case B AMC TX interfering impact towards other systems rather than as the expected typical impact. With the assumed power settings, the minimum frequency distance for interference-free operation of the DME_A RX mounted on a close aircraft at 600 m vertical separation is 2 MHz. The comparable frequency distance (1.5 MHz) is sufficient to protect the ground DME RX from the airborne B-AMC TX at a distance of 600 m. The same frequency spacing (1.5 MHz) should be enough to protect an airborne DME receiver at 600 m distance from the ground B-AMC TX. An airborne SSR RX is always protected from the airborne or ground B-AMC TX at 600 m distance. With 50 dbm default B-AMC_A TX power, a ground SSR RX would temporary experience problems even at relatively large distance (8 km). This could be completely mitigated by reducing the B-AMC_A TX power to 38.5 dbm. B-AMC aircraft flying at any FL would not influence ground GSM/UMTS mobile or base station equipment. The required minimum distance of parked aircraft to the GSM/UMTS mobile terminals with +50 dbm B-AMC TX power is 12/75 m, respectively. Similar minimum distances are required between parked aircraft and GSM/UMTS base stations. When reduced power of the airborne B-AMC TX is assumed (+38.5 dbm), the distances are correspondingly shortened (by factor 3.75), but the distance to the UMTS mobile equipment (20 m) would still require further validation. NOTE: As no representative data were available, all results have been obtained without assuming any front-end selectivity in the interfering B-AMC transmitter and victim L-band receivers. It is recommended to obtain the RF selectivity data and to review the results of this document taking such new aspects into account. However, GSM and UMTS mobile terminals and base stations are being designed by applying careful RF engineering practices. Taking such selective RF components into account would significantly influence the results obtained in this document. With +50 dbm B-AMC TX power, ground and airborne B-AMC TXs would jam airborne or ground UAT receivers in spite of large frequency and spatial distance. The problem can be solved by reducing the B-AMC transmitting power to +38.5/35 dbm for B-AMC airborne/ground transmitter, respectively, and additional RF filtering in front of the UAT receivers. Preliminary estimates are also available for the case where the ground B-AMC TX influences ground DME, SSR, UAT and GSM/UMTS receivers. It is important to note that ground co-location is usually regarded as an engineering challenge (local implementation issue) and that in some cases additional measures (e.g. filtering) may be envisioned, even at the side of the legacy aeronautical equipment. Page: 1-3

15 During this work the inconsistency of input data and the lack of common metrics for interference investigations was identified as a major problem. It is recommended to establish comprehensive common assumptions and common interference evaluation criteria for all candidate L-band technologies and to review the results of the calculations (or repeat calculations) presented here based on such common criteria. Section 8 describes the aspects of airborne co-location of B-AMC and other L-band systems. One common characteristics of existing L-band airborne systems is that their transmitters operate at relatively high power levels and that the isolation provided between L-band antennas is very limited. At the same time, the receivers of such systems are expected to operate at sensitivity levels that may be as low as -97 dbm (UAT). Taking into account that both the RX out-of-band rejection capability and the TX out-of-band noise floor are limited, this creates a very difficult situation with respect to airborne system co-location. It can be generally concluded that, regardless of the mutual frequency separation, an airborne B-AMC RX would be de-sensitised by the radiated out-of-band broadband noise each time one of the airborne L-band systems starts to transmit. To cope with that kind of interference, the B-AMC system design comprises strong FEC techniques. Similarly, an airborne L-band RX would be de-sensitised by the radiated out-of-band broadband noise each time an airborne B-AMC TX starts to transmit. Using the suppression bus has been considered as acceptable in the UAT context and is proposed for the B-AMC system as well. The B-AMC TX would drive the suppression bus during time periods that are slightly longer than the actual B-AMC reverse link transmissions. The receivers of other L-band systems may use this information to protect their inputs from high power levels. Similarly, the B-AMC RX may has to protect its input circuitry when any other L-band system decides to transmit. An initial investigation of the duty-cycle associated with the anticipated usage of the B-AMC reverse link has been performed throughout this section. The detailed assessment of the duty-cycles of airborne L-band transmitters connected to the mutual suppression bus (including the B-AMC TX) and the investigation of an operational impact of the blockage produced upon other systems by an active airborne B-AMC TX represents an important task for the future work on the B-AMC system validation. Some aspects of the TX and RX design have been highlighted in Section 9. It may be beneficial to consider an RF band-pass pre-selection filter within the airborne B-AMC RX, as it would remove most of the direct interference power received from L-band systems operating outside the RF filter bandwidth. It is equally important to use for B-AMC upand down conversion local oscillators with the state-of-the-art spectral purity (low phase noise, low spurious products). Generally, linear TX power amplifier should be used. The level of the IMD products is dependent on the power amplifier nonlinearity characteristics and can be predicted by knowing the PA interception points (IPx). RF post-filtering after the PA could reduce the level of spurious signals and broadband noise that may appear at large frequency offsets from the B-AMC TX channel. Section 10 provides brief information about expected RF bandwidth associated with the B-AMC system operation. A simple calculation of the total available RF bandwidth for the cellular B-AMC system has been performed in [B-AMC D2.2]. Assuming 7 cells per cell cluster and ideal cellular planning, 7 paired L-band FL/RL B-AMC channels separated by the FDD distance would be required for regional (Europe-wide) B-AMC ENR coverage. Wherever possible, TMA and APT operational coverage should be provided by a single Page: 1-4

16 B-AMC GS, operating on a single FL/RL channel pair. However, some TMAs and APTs may for coverage reasons require multiple FL/RL channels. The total amount of L-band spectrum required for providing B-AMC A/G services therefore will also depend on the TMA terrain and APT topology that cannot be influenced by the B-AMC technology development. In the A/A mode, a single dedicated B-AMC RF channel (CCC) with 2.6 MHz bandwidth should be used. Therefore, the total required bandwidth for B-AMC A/A operations is at maximum 2.6 MHz END OF SECTION Page: 1-5

17 2. Introduction This section provides an overview of the B-AMC study background, study specific context and in particular the rationale for introducing this new B-AMC broadband technology. Finally, it summarises the goals of the "WP4 Spectrum Compatibility Issues" and in particular objectives covered by this deliverable "B-AMC Interference Analysis" and Spectrum Requirements Study Background The frequency band currently used for air ground communications ( MHz) is becoming congested. In some parts of Europe, it is extremely difficult to find a frequency to allow an assignment to be made. With the predicted increase in the number of flights, this situation will get worse. Although there is a programme in place to alleviate this problem by reducing channel spacing in the band from 25 khz to 8.33 khz, the relief that it will provide in terms of enabling the required assignments to be made will not satisfy demand in the long term. In addition to voice communications, future Air Traffic Management (ATM) concepts will require a much greater use of data communications than is employed in the current system. The International Civil Aviation Organisation (ICAO), through its Aeronautical Communications Panel (ACP), is seeking to define a Future Communication System (FCS), to support ATM operations. In response, the Federal Aviation Administration (FAA) and EUROCONTROL initiated a joint study, with support from the National Aeronautics and Space Administration (NASA) and United States (U.S.) and European contractors, to investigate suitable technologies and provide recommendations to the ICAO ACP Working Group T (former WG-C). The first stage of the study was to conduct technology prescreening, which has been completed. More than 50 candidate technologies were assessed as part of the pre-screening activity. Some of those technologies will be carried forward to the next stage, which is to perform an in-depth analysis to identify those technologies that will meet the functional, performance and operational communications requirements of a future ATM system. These technology investigations will conclude in Q Within Europe, the ACP members agreed to adopt a two step approach to technology selection. Step 1 was to identify potential technologies, based upon their ability to meet a subset of the criteria contained in the EUROCONTROL / FAA Communications Operating Concept and Requirements (COCR) document [COCRv2]. In Step 2, additional considerations / investigations addressing the concerns covered by the other initial selection criteria will be applied to the Step 1 selected technologies, aiming to produce a further short list and recommendations for implementation. The FCS will be the key enabler for new ATM services and applications that will bring operational benefits in terms of capacity, efficiency and safety. The FCS will support both data and voice communications with an emphasis on data communications in the shorter term. It must support the new operational concepts, as well as the emerging requirements for communications of all types (both voice and data) with a minimum set of technologies deployed globally. The FCS will incorporate new technologies as well as the legacy systems that will continue to be used. This study, of which this report is part, will contribute to the ongoing work of FCS investigations by providing an in-depth evaluation of one of the technologies carried Page: 2-1

18 forward from the Step 1 activity. The technology under consideration is Broadband Very High Frequency (B-VHF) Specific Context The B-VHF project was a research project co-funded by the European Commission s Sixth Framework Programme. The project investigated the feasibility of a new multi-carrierbased wideband communication system to support aeronautical communications, operating in the VHF communication band. The B-VHF project has completed a substantial amount of work in developing and designing the system for operation in the VHF band. However, the "overlay" implementation option is regarded only feasible with considerable effort to be spent for implementing all measures for mitigating the interference and since there is no spectrum available in the VHF band for a dedicated B-VHF implementation, the investigation is now considering the implementation of a similar technology but in a different band. The candidate bands are:! VHF navigation band: [112 or 116] 118 MHz! L band: 960 [1024 or 1164] MHz! C band: [5030 or 5091] 5150 MHz Each of the above bands is already being used by other systems. Therefore, detailed compatibility analyses between the new and existing systems must be the undertaken. The B-AMC study will evaluate the possibility of implementing a system using similar technology to B-VHF but in the L-band from MHz. The generic name given to the system is Broadband - Aeronautical Multi-Carrier Communication (B-AMC). At the kick-off meeting, EUROCONTROL suggested that Work Package 1 (WP1) of this study should investigate three options with regard to the spectrum that could be used for the B-AMC technology.! OPTN1 - study the feasibility of utilising spectrum between successive Distance Measuring Equipment (DME) channels for B-AMC. This would allow for B-AMC frequency planning that is "independent" from DME planning. If "enough" spectrum is available, the B-AMC would be deployed as an inlay system in the L-band.! OPTN2 - if option 1 proves to be not feasible, study the feasibility of assigning frequencies to B-AMC channels in areas where they are not used locally by DME. This would require the establishment of a relationship between potential B-AMC assignments and existing DME assignments.! OPTN3 - if neither option 1 nor option 2 proves to be feasible, investigate the feasibility of utilising the lower part of the band ( MHz) for B-AMC, considering potential interference to the Global System for Mobile communications (GSM), which is operated in the lower adjacent band. With the first two options, B-AMC is more an "inlay" than a real overlay system. The B-AMC system will not attempt to re-use the DME channel allocations that appear on 1 MHz grid, B-AMC channels will be rather placed at 500 khz offset from the nominal DME channel assignment. The third option is neither inlay nor overlay, but it follows traditional spectrum allocation methods. Page: 2-2

19 2.3. Objectives of Work Package 4 This deliverable "B-AMC Interference Analysis and Spectrum Requirements" presents the results of the work conducted within "WP4 - Spectrum Compatibility Issues" of the B-AMC study. In this WP, simple qualitative investigations of the mutual interference between the B-AMC system and different L-band systems have been performed, by using analytical methods and limited MATLAB investigations. The goal of these preliminary investigations is to determine possible effects produced by the signals of different L-band systems onto the B-AMC system receiver, as well as to estimate the maximum allowed amount of the B-AMC signal power at the input of the victim L-band receivers. Quantitative interference investigations are conducted in "WP5 Capacity and Performance Analysis", as the interference impact on the physical layer affects the entire performance of the B-AMC system END OF SECTION Page: 2-3

20 3. Characteristics of L-band Transmitters This chapter captures the parameters of ground and airborne L-band transmitters that may interfere with the airborne or ground B-AMC receiver TX Parameters Table 3-1 captures the most important parameters of L-band transmitters that are relevant for interference investigations. Blue shaded table entries represent the original values related to the TX power gathered from reference documents. Values in the column TX Power represent either originally specified- or calculated values for the power at the terminals of the interfering transmitter. DME_A, MIDS_A and MIDS_G "TX Power" values were obtained from [FSCA-L]. "TX power" for UMTS_M system has been obtained from [ETS-101]. "TX Power" values for BAMC_A and BAMC_G are assumed values. "TX Power at Antenna Port" values for SSR_A, UMTS_G, and GSM_M/GSM_G systems were obtained from [ANN10-IV], [ETS-104] and [TS45-005], respectively. "EIRP" values for DME_G, SSR_G and UAT_A/UAT_G systems were derived from [EUR- FMM], [DO-292] and [UAT_S], respectively. Antenna patterns (indicated in the "Ant. type" column) have been assumed as described in Section 5. The applicable maximum antenna gain is indicated in the "Max. Ant. Gain" column. For SSR ground station, an isotropic antenna (antenna type: "OMNI") with 27 dbi gain [AMS Radars] was assumed. For a MIDS ground station, the vertical antenna pattern and gain were assumed to be the same as for airborne MIDS installations. The gains of airborne MIDS and SSR antennas were assumed to be the same as the gain of typical DME antenna (5.4 dbi). For all aeronautical ground stations and UMTS/GSM base stations cable losses of 2 db were assumed (column "Cable Loss"). For all airborne installations cable losses of 3 db were assumed. For mobile GSM and UMTS terminals no cable losses apply and an isotropic antenna (antenna type: "OMNI") were assumed. Preliminary frequency ranges for BAMC_A and BAMC_G systems (have been selected in order to achieve maximum frequency separation from the UAT channel (978 MHz) as well as SSR 1030 MHz and 1090 MHz channels. NOTE: The interference investigations in this document have been conducted by respecting the above sub-bands. The detailed sub-band specification and the specification of the B-AMC duplex spacing requires further work. The B-AMC system design is robust enough to allow re-considering the proposed sub-bands should it become necessary (e.g. placing B-AMC channels between 1111 and 1135 MHz would increase duplex spacing to 126 MHz and probably significantly ease the implementation of the TX/RX diplexer). Within each sub-band 24 channels are anticipated to be available for the B-AMC FL and RL. Page: 3-1

21 ID Transmitter System ID TX Operating Range TX Power Cable Loss Ant. Type TX Power at Antenna port Max. Ant. Gain EIRP 1 MHz dbm db dbm dbi dbm 2 DME airborne TX DME_A DME_A 60 5,4 65,4 3 DME ground TX DME_G DME_G SSR airborne TX SSR_A DME_A 57 5,4 62,4 5 SSR ground TX SSR_G ,5 2 OMNI 55,5 27,00 82,5 6 UMTS900 mobile TX UMTS_M OMNI UMTS900 BS TX UMTS_G UMTS_G GSM900 mobile TX GSM_M OMNI GSM900 GS TX GSM_G UMTS_G UAT airborne TX UAT_A ,6 3 DME_A 52,6 5, UAT ground TX UAT_G DME_G MIDS airborne TX MIDS_A , , MIDS_A 50 5,4 55,4 13 MIDS ground TX MIDS_G , , MIDS_A 51 5,4 56,4 14 BAMC airborne TX BAMC_A ,1 3 DME_A 42,1 5,4 47,5 15 BAMC ground TX BAMC_G ,1 2 DME_G 43,1 8 51,1 Table 3-1: Parameters of L-band transmitters Page: 3-1

22 3.2. DME airborne TX The airborne DME TX operates in the frequency range MHz subdivided into channels of 1 MHz bandwidth [FSCA-L]. It transmits pulse pairs to DME ground stations and waits for a response on a channel 63 MHz below or above the designated interrogator frequency TX Spectral Characteristics Both pulses of the transmitted pulse pair have approximately a Gaussian shape as depicted in Figure 3-1. The pulse duration is only 3.5 µs +/-0.5 µs [B-AMC D1]. Hence, the spectrum of the DME signal is expected to be broad such that it uses major parts of the available channel bandwidth of 1 MHz. Figure 3-1: DME pulse envelope The spectrum of the DME signal has to fulfil several requirements defined in the standards. The spectrum of the pulse modulated signal shall be such that at least 90 per cent of the energy in each pulse shall be within 0.5 MHz in a band centred on the nominal channel frequency [B-AMC D1]. Page: 3-1

23 According to a recommendation in [ANN10-I], the power contained in a 0.5 MHz band centred on frequencies 0.8 MHz above and 0.8 MHz below the nominal channel frequency should be at least 23 db below the power contained in 0.5 MHz band centred on the nominal channel frequency. The power contained in a 0.5 MHz band centred on frequencies 2 MHz above and 2 MHz below the nominal channel frequency should be at least 38 db below the power contained in 0.5 MHz band centred on the nominal channel frequency. Any additional lobe of the spectrum is of less amplitude than the adjacent lobe nearer to the nominal channel frequency. NOTE: This recommendation becomes a mandatory requirement in [DO-189]. The required shape of the transmit spectrum of the airborne DME transmitter is shown in Figure db 38 db Figure 3-2: Airborne DME Transmitter Spectrum (0.5 MHz Measurement BW) The power of spurious emissions of the DME interrogator when no pulse pair is occurring should be below -47 dbm within the band MHz [FSCA-L]. Near to the frequencies 1030 and 1090 MHz a maximum allowed spurious level of -57 dbm applies. If the aircraft is using TCAS, no more than -67 dbm is allowed near to 1030 and 1090 MHz. This limit is further reduced to -79 dbm for aircraft with dual DME installation TX EIRP and Duty Cycle [FSCA-L] and [DO-189] state that the peak output power of the interrogator (TX output) should not exceed 2 kw (+63 dbm). The DME interrogator transmits up to 150 ppps on the designated channel when it is in search mode [B-AMC D1]. Once it receives an answer from the ground station, the interrogator reduces the number of transmitted pulse pairs to 30 ppps in track mode. The maximum duty cycle of 150 ppps only occurs in brief intervals. As most of the time only 30 ppps are transmitted, in [FSCA-L], a duty cycle of 0.03% is assumed. Page: 3-2

24 3.3. DME ground TX The ground DME TX uses 1 MHz channels in the MHz range. It responds to the interrogations from aircraft on paired channels either 63 MHz below or above the corresponding interrogation frequency [FSCA-L]. Like the airborne DME, TX Gaussianshaped pulse pairs are transmitted that are characterized in time and frequency domain in the following TX Spectral Characteristics The ground DME TX generates pulse pairs consisting of two pulses with an approximately Gaussian shape. For the duration of one pulse the same values as for the airborne TX apply (Section 3.2.1). The spectrum of the pulse modulated signal shall be [B-AMC D1] such that during the pulse the effective radiated power contained in a 0.5 MHz band centred on frequencies 0.8 MHz above and 0.8 MHz below the nominal channel frequency in each case shall not exceed 200 mw (+23 dbm). The effective radiated power contained in a 0.5 MHz band centred on frequencies 2 MHz above and 2 MHz below the nominal channel frequency in each case shall not exceed 2 mw (+3 dbm). The effective radiated power contained within any 0.5 MHz band shall decrease monotonically as the band centre frequency moves away from the nominal channel frequency [B-AMC D1]. [ED-57] provides the typical spectrum envelope shape (Figure 3-3) for the ground DME transmitter. ERP (dbm) 200 mw = 23 dbm 2 mw = 3 dbm Figure 3-3: Ground DME Transmitter Spectrum (0.5 MHz Measurement BW) The spurious power level shall be more than 80 db below the peak pulse power [FSCA-L]. At all frequencies from 10 to 1800 MHz, but excluding the band of frequencies from 960 to 1215 MHz, the spurious output of the DME transponder transmitter shall not exceed - 40 dbm in any one khz of receiver bandwidth [FSCA-L]. Page: 3-3

25 TX EIRP and Duty Cycle The typical ground DME TX output power is 1 KW (60 dbm) [FSCA-L]. The typical TACAN ground transmitter power is 3 KW (65 dbm) [FSCA-L]. [EUR-FMM] advises 37 dbw (67 dbm) as maximum en-route DME transmitted EIRP and 40 dbw (70 dbm) as maximum TACAN EIRP. For the purpose of this work the EIRP = 70 dbm has been retained as the worst-case for ground DME/TACAN installations. The duty cycle of DME ground transponders is typically between 700 and 3600 ppps [B- AMC D1]. A DME ground transponder transmits at least 700 ppps and 2700 ppps at the maximum. The value of 2700 ppps also applies for DME transponders with fixed rate. The duty cycle of a TACAN ground transponder shall not exceed 3600 ppps. In the following the maximum duty cycle of 3600 ppps of a TACAN station will be assumed in order to consider the worst case SSR airborne TX An airborne SSR transponder operates (transmits) on 1090 MHz ± 3 MHz. NOTE: The same transmit frequency is used by airborne Mode S ES ADS-B equipment TX Spectral Characteristics The required spectrum limits for the Mode S airborne transponder from [FSCA-L] are shown in Figure 3-4. The spectral mask requests an attenuation of only 3 db at 1.3 MHz offset from the SSR carrier frequency and an attenuation of 60 db at 78 MHz offset. According to [FSCA-L] recommendation, the transponder CW radiation should not exceed -70 dbw. Page: 3-4

26 Figure 3-4: Airborne SSR Transponder Spectral Mask ACAS Interrogator [ANN10-IV] states that when airborne ACAS is not transmitting an interrogation, the effective radiated power in any direction shall not exceed 70 dbm. NOTE: ACAS interrogations are transmitted by an airborne interrogator at 1030 MHz, replies are received at 1090 MHz. The ACAS interrogator spectrum on 1030 MHz shall correspond to the spectrum of the ground SSR Mode S interrogator (Figure 3-5). The ACAS reply spectrum and Mode S squitters (acquisition squitter, extended squitter) on 1090 MHz shall correspond to the spectrum of the airborne SSR Mode S transponder (Figure 3-4) TX EIRP The peak pulse power at the antenna terminals shall be between 21 dbw and 27 dbw (57 dbm) [FSCA-L]. [ANN10-IV] states that the peak power of each reply pulse shall not exceed 27 dbw. Page: 3-5

27 ACAS TX [ANN10-IV] states that the effective radiated power of an ACAS transmission at 0 degree elevation relative to the longitudinal axis of the aircraft shall not exceed 27 dbw (57 dbm) SSR ground TX A ground SSR interrogator operates (transmits) on 1030 MHz ± 0,2 MHz. NOTE: The same transmitting frequency is used by airborne ACAS equipment (interrogator) TX Spectral Characteristics The required spectrum limits for the Mode S ground interrogator from [FSCA-L] are shown in Figure 3-5. Recommendation: Interrogator CW radiation should not exceed -76 dbw [FSCA-L]. When the interrogator transmitter is not transmitting an interrogation, its output shall not exceed 5 dbm effective radiated power at any frequency between 960 MHz and 1215 MHz [ANN10-IV]. Figure 3-5: Ground SSR Interrogator Spectral Mask Page: 3-6

28 TX EIRP EIRP is not limited for a ground SSR TX, but it is recommended to reduce the power to the lowest value required to achieve a required operational range [FSCA-L]. [DO-292] suggests 52.5 dbw (82.5 dbm) as a maximum EIRP of the ground SSR TX UMTS900 mobile TX UMTS900 (Band VIII) mobile TX transmits in the range MHz TX Spectral Characteristics [ETS-101] provides the spectral mask for the UMTS mobile TX operating in the Band VIII. The mask is specified up to the maximum offset of 12.5 MHz. The occupied channel bandwidth shall be less than 5 MHz, based on a chip rate of 3.84 Mcps. The mask is specified as relative power (dbc) of out-of-channel emission relative to the RRC filtered mean power of the mobile TX carrier. The mask is measured with filter of 30 khz/1 MHz BW at a specified offset f between the carrier frequency and the centre of the measurement filter. NOTE: Only the highest mobile power class (+24 dbm) is considered for B- AMC/UMTS900 interference investigations. It was assumed that the mobile TX signal power spectrum is flat within 5 MHz bandwidth, so the spectrum density is at about +1,8 dbm/30 khz within that range. NOTE: Attenuation values obtained with 1 MHz filter bandwidth have been re-calculated (reduced for 15 db) to the 30 khz bandwidth (5 th and 7 th row in Table 3-2). UMTS Mobile Max. power = 24 dbm (assumed to be flat over ± 2,5 MHz) BW (khz) f (MHz) 0,000 2,500 2,500 3,500 3,500 7,500 8,500 12,000 P (dbc/bw) -35,0-50,0-35,0-39,0-49,0-49,0 P (dbc/30 khz BW) -35,0-50,0-50,2-54,2-64,2-64,2 P (dbm/30 khz BW) 1,8 1,8-11,0-26,0-26,2-30,2-40,2-40,2 Normalised to 0 db 0,0 0,0-12,8-27,8-28,0-32,0-42,0-42,0 Table 3-2: UMTS Mobile TX Spectral Mask (P = +24 dbm) Page: 3-7

29 0,0-5,0 Relative Power in 30 khz Bandwidth -10,0-15,0-20,0-25,0-30,0-35,0-40,0-45,0 0,000 2,000 4,000 6,000 8,000 10,000 12,000 14,000 Offset (MHz) Figure 3-6: UMTS Mobile TX Spectral Mask Spurious emissions of an UMTS mobile TX excluding the range of ± 12.5 MHz around the mobile TX centre frequency - should lie [ETS-101] below! - 36 dbm for frequencies below 1 GHz, measured in 100 khz BW! - 30 dbm for frequencies above 1 GHz, measured in 1 MHz BW Spurious emissions for Band VIII mobile TX should be below! - 79 dbm for frequencies between 935 and 960 MHz, measured in 100 khz BW TX EIRP UMTS mobile TX maximum output power is +24 dbm [ETS-101] UMTS900 BS TX UMTS900 (Band VIII) BS TX transmits in the range MHz TX Spectral Characteristics [ETS-104] provides the TX spectral mask for the UMTS base station operating in the Band VIII. The mask is specified up to the maximum offset of 12.5 MHz. The occupied channel bandwidth shall be less than 5 MHz, based on a chip rate of 3.84 Mcps. Page: 3-8

30 The mask is specified as absolute power (dbm) measured with filter of 30 khz/1 MHz BW at a specified offset f between the carrier frequency and the centre of the measurement filter. NOTE: Only the highest base station power class (+43 dbm) is considered for B- AMC/UMTS900 interference investigations. It was assumed that the signal power spectrum is flat within 5 MHz bandwidth, so the spectrum density is at about +20,8 dbm/30 khz within that range. NOTE: Attenuation values obtained with 1 MHz filter bandwidth have been re-calculated (reduced for 15 db) to the 30 khz bandwidth (6th and 7 th row in Table 3-3). UMTS BS Max. power = 43 dbm (assumed to be flat over ± 2,5 MHz) BW (khz) f (MHz) 0 2,515 2,515 2,715 3, P (dbm/bw) -14,0-14,0-26,0-26,0-13,0-13,0 P (dbc/30 khz BW) P (dbm/30 khz BW) 20,8 20,8-14,0-14,0-26,0-26,0-28,2-28,2 Normalised to 0 db 0,0 0,0-34,8-35,0-47,0-47,0-49,2-49,2 Table 3-3: UMTS BS Spectral Mask (P = +43 dbm) 0,0 Relative Power in 30 khz Bandwidth -10,0-20,0-30,0-40,0-50,0-60, Offset (MHz) Figure 3-7: UMTS BS Spectrum Emission Mask TX EIRP UMTS base station operation in Band VIII with maximum power of +43 dbm was assumed, measured at the antenna connector [ETS-104]. Page: 3-9

31 3.8. GSM900 mobile TX GSM900 mobile TX operates (transmits) in the MHz range [ECC 96], [FSCA-L]. The requirements are given in terms of power levels at the antenna connector of the equipment. For equipment with integral antenna only, a reference antenna with 0 dbi gain shall be assumed TX Spectral Characteristics [TS45-005] provides the spectral mask of the GSM900 mobile TX, separately for different power classes. The mask is specified as a power measured in 30 khz/100 khz BW at a specified offset f relative to the power measured in the same BW at zero offset. NOTE: Only the highest power class (+39 dbm) is considered for B-AMC/GSM900 interference investigations. Attenuation values obtained with 100 khz filter bandwidth have been re-calculated (reduced for 5 db) to the 30 khz bandwidth (bold values in Table 3-4). TX Power (dbm) 39 Measurement BW f (MHz) < 3 3 < khz Att (db) +0, khz Att (db) Table 3-4: GSM Mobile TX Spectral Mask Figure 3-8 shows the corresponding mobile transmitter pulse spectrum [FSCA-L]. Figure 3-8: GSM900 Mobile TX Spectral Mask Page: 3-10

32 Out-of-band mobile GSM TX spurious power shall be no more than! -36 dbm in the frequency band 500 MHz to 1 GHz and! -30 dbm in the frequency band 1 GHz to GHz when measured in " 30 khz BW for 2 MHz offset from edge of the transmit band " 100 khz BW for 5 MHz offset from edge of the transmit band " 300 khz BW for 10 MHz offset from edge of the transmit band " 1 MHz BW for 20 MHz offset from edge of the transmit band " 3 MHz BW for 30 MHz offset from edge of the transmit band TX EIRP The GSM900 mobile TX maximum output power (power class 2, GMSK modulation) is +39 dbm [FSCA-L], [TS45-005] GSM900 BS TX GSM900 BS TX is operating (transmitting) in the band MHz [ECC 96]. The requirements are given in terms of power levels at the antenna connector of the equipment. NOTE: [FSCA-L] (wrongly) states that the transmission is in MHz range TX Spectral Characteristics [TS45-005] provides the spectral mask of the GSM900 BS, separately for different power classes. The mask is specified as a power measured in 30 khz/100 khz BW at a specified offset f relative to the power measured in the same BW at zero offset. NOTE: Only the highest power class (+43 dbm) is considered for B-AMC/GSM900 interference investigations. Attenuation values obtained with 100 khz filter bandwidth have been re-calculated (reduced for 5 db) to the 30 khz bandwidth (bold values in Table 3-4). TX Power (dbm) 43 Measurement BW f (MHz) < < < khz Att (db) +0, khz Att (db) Table 3-5: GSM BS TX Spectral Mask Figure 3-9 shows the GSM900 BS transmitter pulse spectrum [FSCA-L]. Page: 3-11

33 Figure 3-9: GSM900 BS TX Spectral Mask In-band spurious base station TX power within the transmit band shall be no more than! -36 dbm for offset from carrier 1.8 MHz and 30 khz measurement BW! -36 dbm for offset from carrier 6 MHz and 100 khz measurement BW NOTE: In-band spurious performance is of no interest for B-AMC/GSM900 interference investigations. Out-of-band BS TX spurious power shall be no more than! -36 dbm in the frequency band 500 MHz to 1 GHz and! -30 dbm in the frequency band 1 GHz to GHz when measured in " 30 khz BW for 2 MHz offset from edge of the transmit band " 100 khz BW for 5 MHz offset from edge of the transmit band " 300 khz BW for 10 MHz offset from edge of the transmit band " 1 MHz BW for 20 MHz offset from edge of the transmit band " 3 MHz BW for 30 MHz offset from edge of the transmit band TX EIRP The GSM900 BS TX maximum output power at the input of the base station combiner (power class 1) should be less than 640 W (+58 dbm) [FSCA-L], [TS45-005]. It is assumed that combiner has 1 db losses and appears between the transmitter and the Page: 3-12

34 antenna feeder cable, so additional combiner and cable losses will reduce the TX power for 3 db (+55 dbm at antenna input). NOTE: In [ECC 96] the GSM BS power of +43 dbm has been assumed for interference investigations JTIDS/MIDS TX JTIDS/MIDS is based on a time-division multiple-access scheme combined with frequency hopping. The transmission frequency changes randomly between two consecutive pulses. For frequency hopping, 51 frequencies in the L-band are used. The frequencies are aligned with DME channels and are spaced at 3 MHz intervals TX Spectral Characteristics The pulse spectrum roll-off specification defined in [FSCA-L] is shown in Figure Figure 3-10: JTIDS/MIDS TX Spectral Mask NOTE: Line segments are linear on the log-log scale. Figure 3-11 shows an exemplary measured JTIDS/MIDS spectrum as provided in [DO-292]. This figure suggests that most of the transmitted power is contained within ± 3 MHz bandwidth. Page: 3-13

35 Figure 3-11: Measured JTIDS/MIDS TX Spectrum Time Domain Characteristics The JTIDS TDMA structure is based on time slots with a fixed duration of ms. In each time slot either 72, 258, or 444 pulses can be transmitted depending on the message structure. Each pulse lasts 13 µs. Data are transmitted within 6.4 µs. The remaining part of the pulse is a silent period, including 800 ns pulse rise and fall times. During the active part of the pulse minimum shift-keying (MSK) modulated data spread by a 32 bit PN sequence are transmitted. Hence, the active part of the pulse consists of ns chips that mainly cause the large bandwidth of the spectrum TX EIRP and Duty Cycle Maximum JTIDS/MIDS transmitter power is a maximum of 200 W (53 dbm) measured at the terminal output [FSCA-L]. This value is valid for JTIDS terminals in general, i.e. for ground stations as well as for airborne stations. Assuming the standard data format with 258 pulses per time slot, 33,042 pulses per second are transmitted. For transmitting the pulses all 51 hopping frequencies are used according to a pseudo-random pattern. Consequently, 648 pulses per second are transmitted on each frequency. Theoretically, JTIDS is capable of operating more than one JTIDS net simultaneously in the same geographic region by using different frequency hopping patterns. However, this Page: 3-14

36 is currently not permitted by any State. Hence, the maximum number of pulses per second per frequency remains 648. According to [FSCA-L], the standard duty cycle of the JTIDS system is even smaller, as the time slot duty factor is only 50% (one half of all slots remain empty ). This means, that only 129 pulses are transmitted per time slot resulting in 324 pulses per second per frequency UAT Airborne TX UAT TX transmits on frequency of 978 MHz [UAT_S] TX Spectral Characteristics The UAT TX spectrum measured within 100 khz bandwidth defined in [UAT_S] is shown in Figure Linear interpolation should be used between indicated points. 99% of the power of the UAT spectrum is contained in 1.3 MHz (±0.65 MHz). This is roughly equivalent to the 20 db bandwidth. UAT Spectral Mask 0 db Below Maximum % Boundary Frequency offset (MHz) Figure 3-12: UAT TX Spectral Mask TX EIRP Maximum UAT airborne transmitter power is 250 W (54 dbm) measured at the antenna port. The maximum EIRP for a UAT aircraft shall not exceed +58 dbm (including antenna gain) [UAT_S] UAT Ground TX UAT ground TX transmits on frequency of 978 MHz [UAT_S]. Page: 3-15

37 TX Spectral Characteristics The spectral mask for an airborne UAT TX (Figure 3-12) is also valid for the ground UAT TX TX EIRP The maximum EIRP specification (+58 dbm) for an airborne UAT TX is also valid for the ground UAT TX END OF SECTION Page: 3-16

38 4. Characteristics of L-band Receivers This section captures the most important parameters of the L-band receivers that are relevant in interference scenarios with the B-AMC transmitter in the interferer role and these receivers in the victim role DME airborne RX Airborne DME RX in X mode operates (receives) either in the or in the MHz range [FSCA-L]. Airborne DME RX in Y mode operates (receives) either in the or in the MHz range [FSCA-L] RX Selectivity The receiver selectivity is an important factor when dealing with interference, as the receiver selectivity curve combined with the spectrum of the interfering signal determines the frequency-dependent rejection (FDR) curve of the victim RX. [FSCA-L] specifies 1 MHz as a typical airborne DME RX bandwidth. Reference [ECC 96] provides measured selectivity curves (Figure 4-1) of two commercially available airborne DME receivers (DME442, KN62A). DME 442L DME 442R KN62AL KN62AR DME 442LR Figure 4-1: Selectivity of DME 442 and KN62A DME Receivers The selectivity curves are asymmetrical around the centre frequency (DME442L/DME442R, KN62AL/KN62AR). Generally, the broader the RX IF filter the more interference power will effectively appear at the demodulator input. The left DME 442 curve is the broadest one, so the symmetrical version of that curve (bold line in Figure 4-1) has finally been chosen as representative selectivity for an airborne DME receiver. Page: 4-1

39 NOTE: As an airborne DME RX is supposed to nominally operate across the entire L-band ( MHz), the selectivity of the IF filter is the only selectivity available (within the L-band, there is no possibility to benefit from the roofing RF filter in the DMR RX front-end) RX Protection Criteria [DO-189] specifies the RX sensitivity equal to -83 dbm (at the RX input, without all interfering signals). This figure was obtained by assuming 3 db cable losses and 2 db antenna gain. [FSCA-L] specifies -82/-83 dbm at the RX input as airborne DME RX sensitivity level (referring to ICAO Annex 10, Vol. I, Attachment C, section /EUROCAE ED-54 & RTCA DO-189, respectively). [FSCA-L] specifies -99 dbm/mhz as the maximum value of broadband interference power received within the receiver bandwidth (~ 1 MHz). This figure is based on -99 dbm maximum tolerable co-channel CW signal power for dual DME installations [DO-189]. It was supposed that this specification (like the RX sensitivity value) applies to the input of the DME RX DME ground RX Ground DME RX in X or Y mode operates (receives) either in the or in the MHz range [FSCA-L] RX Selectivity [FSCA-L] specifies 1 MHz as a typical ground DME RX bandwidth. No measured selectivity data are available for a ground DME RX. As the signal form is the same as for an airborne RX, it is assumed that the representative airborne RX selectivity (Figure 4-1) also applies to the ground DME receiver RX Protection Criteria [ANN10-I] specifies -103 dbw/m 2 as the power density at the transponder antenna required to trigger the transponder. This corresponds to -96 dbm at the terminals of an isotropic ground antenna. [ED-57] states that the required sensitivity level should be calculated (starting from the [ANN10-I] figure), taking the real antenna gain and cable losses into account. The ground DME receiver should provide reply efficiency greater than 70% in presence of in-band CW with a minimum C/I=10 db [ED-57]. As the ground DME RX handles similar signals as an airborne RX, it should have a similar IF bandwidth as an airborne RX and thus should behave the same way in the presence of an interfering CW or broadband noise signals. Therefore it has been assumed (as in [FSCA-L] for an airborne DME RX) that the above C/I figure is also valid for a broadband noise-like signal as long as it has the same power (within the DME RX bandwidth ~ 1 MHz) as the CW signal. Referring to the above C/I and assuming that the reply efficiency condition has to be fulfilled even at the RX sensitivity level, a single noisy interferer would be tolerable as Page: 4-2

40 long as its power remains below -106 dbm (corresponds to -96 dbm C/I) at the antenna terminals SSR airborne RX An airborne SSR RX operates (receives) at 1030 MHz [FSCA-L]. NOTE: When using 1090 Extended Squitter (ES) for ADS-B purposes, an additional airborne RX operating at 1090 MHz is required RX Selectivity [FSCA-L] specifies 9 MHz as a typical bandwidth of an airborne SSR RX. As no detailed data are available, the selectivity of an airborne SSR RX has been modelled as an ideal rectangular filter with BW = 9 MHz and out-of-band rejection of 70 db. SSR_AL SSR_AR Figure 4-2: SSR_A RX Selectivity (assumed) RX Protection Criteria [FSCA-L] specifies -71 dbm as the sensitivity of an airborne SSR RX operating in Mode A or in Mode C. The sensitivity in Mode S is -74 dbm. These figures are measured at the terminals of the transponder antenna (not at the receiver input). The more stringent value (-74 dbm) for Mode S operation has been chosen as to be representative for an airborne SSR RX. [ECC 64] proposes to use 12 db as S/I criterion for the SSR airborne RX. This figure excludes 6 db aeronautical safety margin and 6 db multiple technology allowance (another 12 db should be added to the S/I figure). Therefore, the total allowable interference at the RX input from single source is equal to = dbm SSR ground RX A ground SSR RX operates (receives) at 1090 MHz [FSCA-L]. Page: 4-3

41 RX Selectivity [FSCA-L] specifies 5.5 MHz as a typical bandwidth of a ground SSR RX. As no detailed data are available, the selectivity of the ground SSR RX has been modelled as an ideal rectangular filter with BW = 5.5 MHz and OOB rejection of 70 db. SSR_GL SSR_GR Figure 4-3: SSR_G RX Selectivity (assumed) RX Protection Criteria [FSCA-L] specifies -103 dbm as the sensitivity of a ground SSR RX (operating in any mode). This figure is measured at the terminals of the transponder antenna (not at the receiver input). [AMS_Radars] specifies 27 dbi as the ground MSSR antenna main beam gain. Assuming 2 db ground cable losses, the sensitivity at the RX input results in -78 dbm. [ECC 64] proposes to use 12 db as S/I criterion for SSR ground RX. This figure excludes 6 db aeronautical safety margin and 6 db multiple technology allowance (another 12 db should be added to the S/I figure). Therefore, the total allowable interference at the RX input from single source is equal to = -102 dbm UMTS900 mobile RX UMTS900 mobile RX receives in the band MHz [ECC 96]. For mobile RXs with an integrated antenna, a reference antenna with 0 dbi gain and 0 db feeder loss is assumed [ECC 82] RX Selectivity [ECC 82] specifies the mobile UMTS RX bandwidth as 3.84 MHz. As no detailed data are available, the selectivity of the mobile UMTS RX has been modelled as an ideal rectangular filter with BW = 3.84 MHz and an out-of-band (OOB) rejection of 70 db. Page: 4-4

42 UMTS_ML UMTS_MR Figure 4-4: UMTS_M/UMTS_G RX Selectivity (assumed) NOTE: Although no data are available, the RF pre-selection filter (covering a range from 925 to 960 MHz) may be available in the UMTS900 mobile receiver front-end. Such a filter would improve the overall RX selectivity at large frequency offsets (e.g., 10 MHz or more) RX Protection Criteria [ETS-101] assumes an antenna gain of 0 db for mobile UMTS terminals with an integrated antenna (zero feeder loss). The reference sensitivity [ECC 82] for mobile UMTS terminals operating in Band VIII is -114 dbm/3.84 MHz. The sensitivity has been specified [ETS-101] for a 12.2 kbps speech channel. It has been assumed that the co-channel S/I ratio of -18 db defined for the base station (BS) in Section 4.6 also applies to the mobile UMTS terminal. Out-of-band band blocking is defined for an unwanted interfering signal falling more than 15 MHz below or above the mobile UMTS terminal receive band and is measured with a CW interfering signal. As the minimum B-AMC operating frequency in the A/G mode is 985 MHz (see section 4.12), only the out-of-band blocking characteristics needs to be considered. The out-of-band blocking requirements for the UMTS900 MS are summarised in Table 4-1: Frequency (MHz) Tolerable CW blocking signal (dbm) Table 4-1: UMTS900 MS Blocking Performance 4.6. UMTS900 BS RX UMTS900 BS RX receives in the band MHz [ECC 96]. All power levels are specified at the antenna connector of the BS RX. [ECC 82] assumes an antenna gain of 18 dbi for rural UMTS BS with an antenna feeder loss of 3 db. Page: 4-5

43 RX Selectivity [ECC 82] specifies the BS UMTS RX bandwidth as 3.84 MHz. As no detailed data are available, the selectivity of the UMTS BS RX has been modelled as an ideal rectangular filter with BW = 3.84 MHz and an OOB rejection of 70 db. UMTS_ML UMTS_MR Figure 4-5: UMTS_M/UMTS_G RX Selectivity (assumed) NOTE: GSM and UMTS base stations are already subject to careful co-site RF engineering practices, using different kinds of duplexers, diplexers and RF filters. Although no data are available, the RF pre-selection filter (covering a range from 880 to 915 MHz) should be available as a part of the UMTS BS receiver front-end. Such a filter would improve the overall RX selectivity at large frequency offsets (e.g., 10 MHz or more) RX Protection Criteria The reference sensitivity for a wide-area UMTS base station is -121 dbm [ETS-104]. The sensitivity was specified for a 12.2 kbps speech channel. A wide-area BS receiving a desired signal with a power of -91 dbm shall meet BER requirements in presence of an interfering AWGN signal with a power of -73 dbm/3.84 MHz. This results in a co-channel S/I ratio of -18 db. NOTE: It has been assumed that this requirement is also valid for the sensitivity level (it is specified with desirable signal 30 db above sensitivity level). Out-of-band band blocking is defined for an unwanted interfering signal falling more than 15 MHz below or above the UMTS BS receive band and is measured with a CW interfering signal. As the minimum B-AMC operating frequency in the A/G mode is 985 MHz (see section 4.12), only the out-of-band blocking characteristics needs to be considered. The out-of-band blocking requirements for the UMTS900 BS are summarised in Table 4-2: Frequency (MHz) Tolerable CW blocking signal (dbm) -15 Table 4-2: UMTS900 BS Blocking Performance Page: 4-6

44 4.7. GSM900 mobile RX GSM900 mobile RX receives in the band MHz [ECC 96]. The requirements are given in terms of power levels at the antenna connector of the equipment RX Selectivity As no detailed RX IF filter characteristics data are available, the selectivity of the mobile GSM RX has been modelled as an ideal rectangular filter with BW = 0.2 MHz and OOB rejection of 70 db. GSM_ML GSM_MR ,5 0 0,5 1 Figure 4-6: GSM_M/GSM_G RX Selectivity (assumed) NOTE: Although no data are available, the RF pre-selection filter (covering a range from 925 to 960 MHz) should be available in the GSM mobile receiver front-end. Such a filter would improve the overall RX selectivity at large frequency offsets (e.g., 10 MHz or more) RX Protection Criteria The sensitivity of a GSM900 mobile RX is -104 dbm [FSCA-L]. NOTE: The lower of the two proposed sensitivity values has been selected. [TS45-005] specifies the co-channel interference ratio (C/I) to be equal to 9 db. These specifications apply to BS RX and all types of mobile RXs, for a desired signal input level of 20 db above the reference sensitivity level, and for a random, continuous, GSM modulated interfering signal. It has been assumed that the specification is applicable to the GSM RX sensitivity level and to the noise-like interfering signal. Out-of-band band blocking is defined for an unwanted interfering signal falling more than 15 MHz below or above the mobile GSM RX terminal receive band and is measured at the antenna connector of the receiver with a CW interfering signal. As the minimum B-AMC operating frequency in the A/G mode is 985 MHz (see section 4.12), only the out-of-band blocking characteristics needs to be considered. The out-of-band blocking requirements for the GSM900 MS are summarised in Table 4-3. Page: 4-7

45 Frequency (MHz) Tolerable CW blocking signal (dbm) 0 Table 4-3: GSM900 MS Blocking Performance 4.8. GSM900 BS RX The GSM900 BS RX receives in the band MHz [ECC 96], [FSCA-L]. The requirements are given in terms of power levels at the antenna connector of the equipment RX Selectivity As no detailed data are available, the selectivity of the GSM BS RX has been modelled as an ideal rectangular filter with BW = 0.2 MHz and OOB rejection of 70 db. GSM_ML GSM_MR ,5 0 0,5 1 Figure 4-7: GSM_M/GSM_G RX Selectivity (assumed) NOTE: GSM and UMTS base stations are already subject to careful co-site RF engineering practices, using different kinds of duplexers, diplexers and RF filters. Although no data are available, the RF pre-selection filter (covering a range from 880 to 915 MHz) should be available as a part of the GSM BS receiver front-end. Such a filter would improve the overall RX selectivity at large frequency offsets (e.g. 10 MHz or more) RX Protection Criteria The sensitivity of the "regular" GSM900 BS RX is -104 dbm [FSCA-L]. NOTE: The lowest offered sensitivity value (from all BS types) has been selected. [TS45-005] specifies the co-channel interference ratio (C/I) to be equal to 9 db. These specifications apply to BS RX and all types of mobile RXs, for a desired signal input level of 20 db above the reference sensitivity level, and for a random, continuous, GSM modulated interfering signal. Page: 4-8

46 NOTE: For B-AMC/GSM interference investigations, it has been assumed that the 9 db criterion is applicable to the sensitivity level and also for the noise-like B-AMC signal. Out-of-band band blocking is defined for an unwanted interfering signal falling more than 15 MHz below or above the GSM BS receive band and is measured at the antenna connector of the receiver with a CW interfering signal. As the minimum B-AMC operating frequency in the A/G mode is 985 MHz (see section 4.12), only the out-of-band blocking characteristics needs to be considered. The out-of-band blocking requirements for the GSM900 BS are summarised in Table 4-4: Frequency (MHz) Tolerable CW blocking signal (dbm) 8 Table 4-4: GSM900 BS Blocking Performance 4.9. JTIDS/MIDS RX JTIDS/MIDS RX receives on a sub-set of total 51 wideband channels in the MHz band [FSCA-L]. JTIDS/MIDS is a military frequency-hopping system that was developed with the goal to be extremely robust against external interference. As the characteristics of a JTIDS/MIDS RX (military system) could not be obtained and the JTIDS/MIDS frequency-hopping system itself should be inherently robust against the B-AMC signal, it was decided to not further investigate this case UAT Airborne RX UAT RX receives at a frequency of 978 MHz [UAT_S] RX Selectivity The RX selectivity specification defined in [UAT_S] for a standard UAT receiver is shown in Table 4-5. This characteristic has been used for the B-AMC interference investigations. The characteristics for the high performance receiver show improved attenuation at lower offsets, but the ultimate attenuation remains the same (60 db at 10 MHz offset). The characteristic has been defined for a not-modulated carrier (CW signal) applied as the interfering signal at the indicated frequency offset. Frequency Offset from Centre Minimum Rejection Ratio (Undesired/Desired level in db ) -1.0 MHz MHz 15 (±) 2.0 MHz 50 (±) 10.0 MHz 60 Table 4-5: UAT Airborne RX Selectivity Page: 4-9

47 NOTE: A worst-case selectivity of -10 db at -1 MHz also was assumed for +1 MHz offset. Additionally, it has been assumed that the UAT RX filter is flat between zero offset and ± 0.8 MHz offset as well as that the out-of-band attenuation remains at 60 db beyond ± 10 MHz. UAT_AL UAT_AR Figure 4-8: UAT_A/UAT_G RX Selectivity RX Protection Criteria A desired signal level of 94 dbm applied at the antenna port (sensitivity) shall produce a rate of Successful Message Reception of 90% or better (basic UAT ADS-B messages) [UAT_S]. The tolerable co-channel continuous wave interference power level for aircraft UAT receivers has been specified as -101 dbm or less at the antenna port UAT Ground RX UAT RX receives at a frequency of 978 MHz [UAT_S] RX Selectivity The ground UAT RX selectivity is assumed to be the same as that of an airborne UAT RX (Figure 4-8). NOTE: As the ground UAT RX is supposed to operate on a single channel (978 MHz), the RF pre-selection filter may be applied to protect the receiver front-end. Such a filter would significantly improve the overall RX selectivity at large frequency offsets (e.g., 10 MHz or more) RX Protection Criteria The sensitivity of a ground UAT RX is defined by the desired signal level of 98 dbm applied at the antenna port [UAT_M]. The tolerable co-channel (978 MHz) CW interference power level for aircraft UAT receivers is assumed to be -106 dbm or less at the antenna port [UAT_M]. The same value has been assumed for noise-like signals. Page: 4-10

48 4.12. L-Band RX Parameters Table 4-6 shows the most important parameters of L-band receivers that are relevant for interference investigations. Blue shaded table entries represent the original values gathered from reference documents. Red values in the column Max. co-channel interference power I at RX input represent calculated values for the interference power at the terminals of the victim receiver. These values have been derived from allowed single-source interference values (indicated in the column Max. I at RX input (within BW) ) by applying a combination of an aeronautical safety margin (SF) of 6 db and a multiple-system allowance (MTA) margin of 6 db. For all aeronautical receivers, an aeronautical safety margin (SF) of 6 db is assumed together with an additional multiple-system allowance (MTA) margin of 6 db. For nonaeronautical receivers (GSM and UMTS), only MTA margin of 6 db is considered. DME_A and UAT_A and UAT_G interference susceptibilities shown in Max. I at RX input (within BW) column were derived from [FSCA-L], [UAT_S] (calculated from -101 dbm at the antenna port including 3 db cable loss) and [UAT_M] (calculated from -106 dbm specified at the antenna port, including 2 db cable loss), respectively. DME_G sensitivity (shown in the S at terminals of an isotropic RX antenna column) was calculated in [ECC 64] based on -103 dbw/m 2 specified in [ANN10-1]. The sensitivities of SSR_A, SSR_G, UMTS_M, UMTS_G and GSM_M/GSM_G receivers are defined at the antenna port ( S at real antenna port column). The corresponding values were derived from [ANN 10-IV], [FSCA-L] (SSR_G sensitivity is assumed to be measured at the antenna terminals), [ETS-101], [ETS-104] and [TS45-005], respectively. Antenna patterns (indicated in the Ant. type column) are assumed according to the description in section 5. The applicable maximum antenna gain is indicated in the Max. antenna gain column. For an SSR ground station, an isotropic antenna (antenna type: OMNI ) with 27 dbi gain [AMS Radars] is assumed. For MIDS ground station, vertical antenna pattern and gain are regarded to be the same as for airborne MIDS installations. The gains of airborne MIDS and SSR antennas are expected to be the same as the gain of typical DME antenna (5.4 dbi). For all aeronautical ground stations and UMTS/GSM base stations cable losses of 2 db are assumed (column Cable loss ). For all airborne installations cable losses of 3 db are supposed. For mobile GSM and UMTS terminals no cable losses apply and an isotropic antenna (antenna type: OMNI ) is presumed. Preliminary frequency ranges for BAMC_A and BAMC_G systems have been selected in order to achieve maximum frequency separation from the UAT channel (978 MHz) as well as the SSR 1030 MHz and 1090 MHz channels. The preliminary total bandwidth for each the BAMC_A and the BAMC_G channels has been estimated to be 24 MHz. Page: 4-11

49 ID Receiver System ID RX operating frequency range S at terminals of an isotropic RX antenna 1 MHz dbm dbi db dbm db dbm db dbm 2 DME airborne RX DME_A DME_A 5, DME ground RX DME_G DME_G SSR airborne RX SSR_A 1030 DME_A 5, , , ,6 5 SSR ground RX SSR_G 1090 OMNI UMTS900 UE RX UMTS_M OMNI UMTS900 BS RX UMTS_G UMTS_G GSM900 UE RX GSM_M OMNI GSM900 BS RX GSM_G UMTS_G UAT airborne RX UAT_A 978 DME_A 5, UAT ground RX UAT_G 978 DME_G MIDS airborne RX MIDS_A , , MIDS_A 5,4 3 N/A 13 MIDS ground RX MIDS_G , , MIDS_A 5,4 2 N/A 14 BAMC airborne RX BAMC_A DME_A 5,4 3-90, , ,5 15 BAMC ground RX BAMC_G DME_G , , ,5 Ant. Type Max. antenna gain S at real antenna port Cable loss Min. signal power S at RX input Required S/I at RX input Max. I at RX input (within BW) Sum of SF and MTA margins Max. co-channel interferer power I at RX input Table 4-6: Parameters of L-band receivers END OF SECTION Page: 4-1

50 5. Characteristics of L-band Antennas For the purpose of interference analysis, it has been assumed that the airborne B-AMC antenna is identical to the airborne DME antenna specified in this chapter. The DME airborne antenna is supposed to be used for both DME and B-AMC operations. Similarly, the representative ground L-band antenna described in this chapter has been assumed to be applicable for both DME transponder and B-AMC ground station Antenna Orientation The orientation of airborne and ground L-band antennas is shown in Figure 5-1. D φ H R θ Figure 5-1: Elevation Angles for Airborne (α) and Ground (φ) Antennas This topology (mutual antenna orientation) has been assumed in all air-ground interference scenarios (for all FLs). A similar topology applies to air-air scenarios where it is assumed that two aircraft are flying at nearly the same FL, with a minimum vertical separation of 600 m. The higher aircraft uses a bottom-mounted antenna, while the lower one uses a top-mounted antenna (like the ground station in the air-ground scenarios). In ground-ground scenarios, both antennas point upwards and the results are provided for the case the antenna main lobes directly point towards each other. Page: 5-1

51 5.2. Airborne Aeronautical L-band Antennas Reference [ECC 96] provides the normalised (G r /G r,max ) gain of an airborne DME antenna for different elevation angles. It is assumed that the elevation and gain pattern is the same for all azimuth angles. The G r,max value is 5.4 dbi (as specified in Recommendation ITU-R M.1639). Reference [GPS_L5] provides the normalised pattern of an airborne MIDS/JITDS antenna, without specifying the maximum antenna gain. As the radiation pattern of the MIDS airborne antenna is similar to the pattern of the airborne DME antenna, it is assumed that the gain of the airborne MIDS antenna is the same (5.4 dbi) as the gain of an airborne DME antenna. The airborne UAT System is expected [UAT_M] to be able to utilize any standard transponder/dme antenna. Therefore, it is expected that an airborne DME_A antenna pattern with a gain of 5.4 dbi can be applied. The DME_A antenna is supposed to be used also for airborne SSR installations. The airborne DME antenna and airborne MIDS antenna patterns are shown in Figure 5-2. The elevation angle α used in Figure 5-2 was previously defined in Figure 5-1. Figure 5-2: Vertical Patterns of Airborne DME and MIDS Antennas 5.3. Ground Aeronautical L-band Antennas [DO-292] provides antenna elevation gain patterns for two (TACAN and DME) ground antennas. [DO-282A] provides another example of vertical patterns for typical ground DME and TACAN antennas that have also been used for UAT investigations [UAT_M]. For the purpose of investigating B-AMC interference, a representative ground DME/TACAN Page: 5-2

52 antenna has been constructed for a given elevation angle by retaining the highest gain of all four real antennas. The maximum peak ground DME antenna gain is assumed to be equal to 8 dbi (as specified in [DO-292]). Vertical patterns of candidate ground antennas and the representative DME_G antenna (bold line) are shown in Figure 5-4. Antennas of ground MIDS terminals are assumed to have the same vertical pattern and the same maximum gain (5.4 dbi) as an airborne MIDS antenna. The representative ground SSR interrogator/receiver vertical antenna pattern (Figure 5-3) has been provided by EUROCONTROL [ECTL], it is assumed (worst-case) that this antenna has a maximum gain of +27 dbi [AMS Radars]. Figure 5-3: SSR Radar Ground Antenna Vertical Pattern The typical UAT ground station antenna has an antenna gain of 6 to 8 dbi with an omnidirectional antenna pattern (the maximum EIRP of the UAT Ground Station is according to UAT SARPs equal to 58 dbm) [UAT_M]. Therefore, the representative DME_G antenna is assumed to be applicable to UAT ground installations as well. Page: 5-3

53 Figure 5-4: DME and TACAN Ground Antenna Vertical Pattern 5.4. L-band UMTS and GSM Antennas Three commercially available 900 MHz high-gain UMTS base station (BS) antennas have been investigated [UMTS_ANT]. For the purpose of investigating the B-AMC interference, a representative ground UMTS/GSM antenna vertical pattern has been constructed for a given elevation angle by retaining the highest gain of all three real antennas. The maximum peak ground UMTS/GSM base station antenna gain is assumed to be 18 dbi, as specified in [ECC 82]. Vertical patterns of the candidate UMTS ground antennas and the representative UMTS/GSM ground antenna (bold line) are shown in Figure 5-5. For the UMTS and GSM mobile terminals, it is assumed that the antenna is omnidirectional with 0 dbi gain. Page: 5-4

54 Figure 5-5: Vertical Patterns of BS UMTS Antennas 5.5. L-band Antennas The most important characteristics of L-band antennas used for the interference investigations are summarized in Table 5-1. Page: 5-5