1、 Report ITU-R SA.2067(11/2005)Use of the 13.75 to 14.0 GHz band by the space research service and the fixed-satellite serviceSA SeriesSpace applications and meteorologyii Rep. ITU-R SA.2067 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economi
2、cal use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by Wo
3、rld and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used
4、for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Serie
5、s of ITU-R Reports (Also available online at http:/www.itu.int/publ/R-REP/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination,
6、amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management Note: This ITU-R
7、Report was approved in English by the Study Group under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2010 ITU 2010 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rep. ITU-R SA.2067 1 REPO
8、RT ITU-R SA.2067 Use of the 13.75 to 14.0 GHz band by the space research service and the fixed-satellite service (2005) CONTENTS Page 1 Introduction 2 2 Use of the 13.75-14.0 GHz band by data relay satellite systems of the space research service. 2 2.1 Data relay satellite networks . 2 2.1.1 Use of
9、the 13.75-14 GHz band . 2 2.1.2 Bandwidth requirements 4 2.2 Summary and conclusions 4 3 Permissible levels of interference in data relay satellite systems that use the 13.75-14 GHz band 4 3.1 Protection criteria for data relay satellite systems 4 3.2 Characterization of interference to the internat
10、ional space station (ISS) from the emissions of a global deployment of FSS GSO earth stations . 5 3.2.1 FSS earth station characteristics 5 3.2.2 GSO satellite locations and distributions . 5 3.2.3 Statistics of the interference to the ISS 7 3.2.4 Discussion of results 9 3.3 Derivation of FSS earth
11、station e.i.r.p. density limits for the protection of international space station operations . 9 3.3.1 International space station forward link system parameters 10 3.3.2 Earth station deployment methodology . 11 3.3.3 Analysis results 13 3.4 Summary and conclusions 19 4 Interference to geostationar
12、y FSS satellites from data relay satellite systems operating in the 13.75-14 GHz band 20 4.1 Orbit separation for the United States of America tracking and data relay satellites 20 4.2 Power flux-density levels at the geostationary-satellite orbit . 20 2 Rep. ITU-R SA.2067 1 Introduction This Report
13、 explains the use of the 13.75-14 GHz band by the space research service (SRS) data relay satellite systems, reviews the permissible levels of interference for SRS data relay satellite systems from Earth-to-space links operating in the fixed satellite service (FSS), and reviews the interference to F
14、SS satellites in geostationary orbit from SRS data relay satellite systems. 2 Use of the 13.75-14.0 GHz band by data relay satellite systems of the space research service The purpose of this section is to address the use by the space research service of frequencies near 14 GHz and to describe the ba
15、ndwidth requirements. 2.1 Data relay satellite networks 2.1.1 Use of the 13.75-14 GHz band In 1983, the United States of America launched the first satellite in its global tracking and data relay satellite system (TDRSS) data relay satellite network. TDRSS relays commands, scientific data and spacec
16、raft health and safety information for a number of NASA low-Earth orbit (LEO) satellites such as the International Space Station, space shuttle, Landsat as well as a number of non-NASA flight missions, including international or joint venture missions. The TDRSS network uses frequencies around 2 GHz
17、, 13/15 GHz and 23/26 GHz to operate and to receive data from low-orbiting satellites. The 13/15 GHz bands are also used for feeder links for the geostationary TDRSS network. Operational tracking and data relay satellites (TDRS) are located at the orbital positions: 41, 46, 171 and 174 W longitude o
18、n the geostationary orbit. The forward link from the TDRS to a LEO spacecraft, relaying critical command, control and ranging data, is centred at 13.775 GHz in the lower portion of the band 13.75-14 GHz. Furthermore, the 13.75-14 GHz band is one segment of several allocations to the space research s
19、ervice between 13.4 and 15.35 GHz that are extensively used for forward and return links to low-Earth orbiting satellites and for feeder links to connect TDRS satellites to their earth stations. This extensive use is evident in the frequency plan for the TDRSS data relay satellite network shown in F
20、ig. 1, particularly between 13.4-14.05 GHz and 14.6-15.225 GHz. This use is the culmination of substantial investments that have been made in system trade-off studies, the development and qualification of space hardware, and the development and implementation of satellite systems and earth stations
21、comprising the TDRSS data relay network. Rep. ITU-R SA.2067 3 Rep.2067-01Space-to-spacelinks13.414.415.415.315.215.115.014.914.814.714.614.514.31.241.141.0413.91.831.731.631.5313.414.415.415.315.215.115.014.914.814.714.614.514.31.241.141.0413.91.831.731.631.53Space-to-EarthlinksTDRSSforward link-to-
22、LEO(Typically10MHzmay beaswideas50MHz)LEO-to-TDRSreturnlinkKu-bandsingle access(KSA)KSA-2PilotCMDKSA-1KSA-2KSA-1MA:multipleaccessKSA:KubandsingleaccessSSA:SbandsingleaccessCMD:commandlinkTLM:telemetrylinkTDRS-to-groundsegmentdowlinkLEO-to-TDRSreturnlinkSS A - 1SS A - 2SS A - 1SS A - 2TLMMAMAFIGURE11
23、3.4-15.4GHzsegmentofthefrequencyplanfortheUnitedStatesofAmericaTDRSSdatarelaysatellitenetwork4 Rep. ITU-R SA.2067 2.1.2 Bandwidth requirements The bandwidth requirements are pictured in Fig. 1. The top portion of this figure shows the links between the TDRS and the LEO satellites in the 13.75-14.0 G
24、Hz band. The forward service links (two independent links per TDRS spacecraft) from the TDRS to low-Earth orbit satellites are used for command, control and ranging and for transmission of data and video. The forward link design is capable of supporting a 25 MSymbol/s transmission rate at a centre f
25、requency of 13.775 GHz. The bandwidth is typically 6 MHz in the case of command and control data, where in most cases the low-rate information data is spread with a 3.08 Mchip/s pseudo-random noise (PN) code. However, in the case of the International Space Station, a bandwidth of 10 MHz is the minim
26、um required to provide for the high-speed TCP/IP data protocols needed for payload telescience, payload management and additional Earth-to-space voice transmission capability effected via the TDRSS network. A 50 MHz bandwidth is required for sending higher rate data to a spacecraft or high resolutio
27、n digital video information to the space shuttle or space station for tele-science and tele-medicine. Reliable transmissions of commands in the 10 MHz around 13.775 MHz are the most critical. The bottom portion of Fig. 1 shows a feeder link used to transmit wideband signals received by the TDRS from
28、 LEO satellites to the TDRSS data relay satellite network earth station. The signals consist primarily of scientific data and spacecraft telemetry. The bandwidth of this link may be up to 225 MHz centred around 13.9 GHz. 2.2 Summary and conclusions This section has addressed the use and bandwidth re
29、quirements of the TDRSS network within the 13.75-14 GHz band. Based on studies within ITU-R, the following are concluded for data relay satellite networks: a comprehensive frequency plan delineates the use of segments of the spectrum extending from 13.4 GHz to 15.225 GHz for service links to low-orb
30、iting satellites and for feeder links to centrally located earth stations; the primary command and control link from the tracking and data relay satellite (TDRS) to the International Space Station is centred at 13.775 GHz with a bandwidth of 10 MHz; an important forward link to low-orbiting satellit
31、es operates with a centre frequency of 13.775 GHz and a bandwidth that can range from 6 MHz to 50 MHz depending on the application; 3 Permissible levels of interference in data relay satellite systems that use the 13.75-14 GHz band This section presents criteria for protection of data relay satellit
32、e systems operating in the 13.75-14 GHz band from Earth-to-space links operating in the FSS. The criteria consist of a permissible level of interference signal power in a specified reference bandwidth at the output of the receiving antenna that is not to be exceeded for more than a specified percent
33、age of time and locations. The largest possible reference bandwidths are specified in order to enable the greatest possible sharing benefit from averaging interfering signal power over bandwidth. 3.1 Protection criteria for data relay satellite systems Recommendation ITU-R SA.1155 gives the permissi
34、ble level of degradation to a data relay satellite link as a 0.4 dB reduction in link power margin, which occurs with an I/N of 10 dB. From this, an aggregate protection criteria of 178 dB(W/kHz) measured at the input to the victim receiver to be exceeded no more than 0.1% of the time is derived. Th
35、is is equivalent to 138 dB(W/10 MHz). The I/N criterion of 10 dB is applicable over a bandwidth of 10 MHz centred at 13.775 GHz, Rep. ITU-R SA.2067 5 although operations can extend over a bandwidth of up to 50 MHz centred at the same frequency. In order to achieve the desired link availabilities, th
36、e interference threshold should not be exceeded for more than 0.1% of the time as a result of the emissions of FSS earth stations in the Earth-to-space direction. The 0.1% of the time is based on the orbital period of the low-orbiting satellites as given in Recommendation ITU-R SA.1155. 3.2 Characte
37、rization of interference to the international space station (ISS) from the emissions of a global deployment of FSS GSO earth stations This section presents the results of an analysis to determine the probability of interference to the ISS for the worst-case orbit for a range of FSS earth station cha
38、racteristics. 3.2.1 FSS earth station characteristics Table 1 is a summary of the characteristics of the FSS earth station populations used in the simulations described within this section. The FSS earth station antenna pattern given in Recommendation ITU-R S.465-5 was used for the analysis presente
39、d in this section. A limited set of simulations were performed comparing results derived from the use of Recommendation ITU-R S.465-5 and Recommendation ITU-R S.1428 and it was found that the difference was less than 1 dB. TABLE 1 Characteristics of FSS earth station populations Earth station signal
40、 info data rate Earth station transmit data rate Signal bandwidth occupancy at satellite transponder Antenna diameter e.i.r.p. (includes 1 dB transmit loss) Average e.i.r.p. density (dB(W/Hz) 16 kbit/s 32 kbit/s 33.6 kHz 0.5 m (34.6 dBi) 33.6 dBW 11.7 64 kbit/s 128 kbit/s 134.4 kHz 1.0 m (41.0 dBi)
41、40 dBW 11.3 1 Mbit/s 2 Mbit/s 2.1 MHz 1.8 m (45.7 dBi) 50.7 dBW 12.5 2 Mbit/s 2 Mbit/s 2.1 MHz 3.0 m (50.2 dBi) 55.2 dBW 8.0 34 Mbit/s 34 Mbit/s 35.7 MHz 4.5 m (53.7 dBi) 69.7 dBW (in 34 MHz) 5.8 3.2.2 GSO satellite locations and distributions A 120 FSS GSO satellite constellation, equally placed 3
42、apart in the geostationary orbit, was used in the analysis. The 4.5 m FSS Gateway earth station distribution is based on the locations of Urban Population Center (UPC) around the world. The UPCs are obtained from the “Urban Agglomerations, 1950-2015, United Nation Population Division, NY, USA”. All
43、the selected UPCs are projected to have a population of one million or more by the year 2015. A total of 326 UPCs were identified. Each satellite will be capable of supporting two links in the same channel using orthogonal polarizations. A total of 240 cities were selected from the urban agglomerati
44、ons. The cities were selected based on the satellite capacity and that the elevation angle to the satellite was greater than 20. The resultant distribution of earth stations is shown in Fig. 2. 6 Rep. ITU-R SA.2067 FIGURE 2 Worldwide distribution of 4.5 m ground stations The FSS earth stations were
45、randomly distributed worldwide based on the population in each continent. The FSS earth stations were randomly allocated to satellites in the geosynchronous arc for which the elevation angle exceeded 20. For each FSS earth station, a satellite with free channels was randomly selected from this group
46、 of satellites. The azimuth and elevation angle for the FSS earth station antenna was computed for the selected satellite. In densely populated areas such as Europe the total number of ground stations exceeds the total number of satellites in the visible arc. Some of the ground stations were not ass
47、igned a satellite and were removed from the analysis. Similarly, satellites above the oceans did not have sufficient ground stations to fill them to capacity. Consequently, those satellites were not fully utilized. Table 2 shows the maximum channel capacity and utilizations of the GSO satellites sup
48、porting the different types of FSS earth stations. TABLE 2 FSS earth station allocations for the simulation Antenna diameter (m) Signal BW occupancy at satellite transponder FSS earth station carriers in 10 MHz bandwidth FSS earth station carriers in 10 MHz per satellite Maximum carriers (FSS earth
49、station) for constellation FSS earth station assignments Utilization (%) 0.5 33.6 kHz 300 600 72 000 60 251 83.6 1.0 134.4 kHz 75 150 18 000 15 100 83.8 1.8 2.1 MHz 5 10 1 200 1 000 83.3 3.0 2.1 MHz 5 10 1 200 1 000 83.3 4.5 35.7 MHz 1 2 240 240 100.0 Rep. ITU-R SA.2067 7 3.2.3 Statistics of the interference to the ISS Simulations, using the orbital geometry of the ISS, were set up to quantify the interference from the FSS earth station emissions. The ISS has an orbit inclination of 51.6 and an altitude of 390 km. In order to make sure that the results
