1、 Rec. ITU-R M.1470 1 RECOMMENDATION ITU-R M.1470 METHODOLOGY OF SHARING BETWEEN MSS SYSTEMS (EARTH-TO-SPACE) AND EXISTING RNSS SYSTEMS (SPACE-TO-EARTH) IN THE FREQUENCY BANDS 149.9-150.05 MHz AND 399.9-400.05 MHz (Question ITU-R 201/8) (2000) Rec. ITU-R M.1470 The ITU Radiocommunication Assembly, co
2、nsidering a) that WRC-97 allocated the band 149.9-150.05 MHz to the MSS on a co-primary basis in the Earth-to-space direction, worldwide, with the radionavigation-satellite service (RNSS); b) that WRC-97 allocated the band 399.9-400.05 MHz to the MSS on a co-primary basis in the Earth-to-space direc
3、tion, worldwide, with the radionavigation-satellite service (RNSS); c) that according to RR No. S5.224A, the use of the bands 149.9-150.05 MHz and 399.9-400.05 MHz by the MSS (Earth-to-space) is limited to the LMSS (Earth-to-space) until 1 January 2015; d) that an existing RNSS system operates in th
4、e bands 149.9-150.05 MHz and 399.9-400.05 MHz in the space-to-Earth direction; e) that according to RR No. S5.220, the MSS shall not constrain development and use of the RNSS in the bands 149.9-150.05 MHz and 399.9-400.05 MHz; f) that according to RR No. S5.224B, the allocation of the bands 149.9-15
5、0.05 MHz and 399.9-400.05 MHz to the RNSS shall be effective until 1 January 2015, recognizing a) that RR No. S4.10 applies to the use of these bands by the RNSS, further recognizing a) that RR No. S4.5 states that “The frequency assigned to a station of a given service shall be separated from the l
6、imits of the band allocated to this service in such a way that, taking into account the frequency band assigned to a station, no harmful interference is caused to services to which frequency bands immediately adjoining are allocated”, and that it is necessary to protect the existing RNSS system from
7、 harmful interference caused by other services, recommends 1 that the technical information for RNSS and MSS (Earth-to-space) systems, which are planned to work within LMSS (Earth-to-space) in the frequency bands 149.9-150.05 MHz and 399.9-400.05 MHz, outlined in Annex 1 be used as baselines and cri
8、teria for the RNSS system protection from LMSS (Earth-to-space) systems; 2 that the methodology of Annex 2 could be used for estimating interference to the RNSS system from the LMSS (Earth-to-space) systems; 3 that the methods described in Annex 3 be used in developing approaches to facilitate the s
9、haring of the 149.9-150.05 MHz and 399.9-400.05 MHz bands by LMSS (Earth-to-space) and existing radionavigation-satellite systems. 2 Rec. ITU-R M.1470 ANNEX 1 Characteristics of the existing RNSS system to be used in evaluating interference between LMSS (Earth-to-space) and RNSS 1 Description of the
10、 TSYKADA space navigation system The TSYKADA space navigation system consists of three basic segments. They are: space segment, ground control segment and user segment. 1.1 The space segment The TSYKADA system is made up of seven satellites placed into seven orbital planes with one satellite in each
11、 plane. The planes are equally separated by ascending node longitude along the equator. The inclination of the orbits is 83. The orbital period is 1 h 45 min. The altitude of the orbit is 1 000 km. The orbit is a circular, near-polar one. The transmitting antenna gain is shown in Figs. 1 and 2. 1.2
12、The ground control segment The ground control segment consists of the system control centre and ground monitoring station network. All of them are located in the Russian Federation territory. The monitoring stations are used to measure satellites orbital parameters and their on-board clock shifts in
13、 relation to the system master clock. Those data are relayed to the system control centre. The centre calculates ephemerides of the satellites and data for their clock updating. That information is relayed to the satellites via the monitoring stations every day. 1.3 The user segment The user segment
14、 consists of navigation equipment installed in maritime ships. The user terminal is made up of antenna, receiver, processor and input/output module. A computer included in the user terminal automatically calculates ship position in relation to a satellite and derives the ship coordinates. The system
15、 uses the passive Doppler position fixing method. Table 1 shows technical characteristics of the RNSS system in the 150 MHz and 400 MHz frequency bands. 1.4 Criteria for protection of the RNSS receiving earth stations Permitted aggregate maximum pfd produced by the MSS stations at the front end (inp
16、ut) of the RNSS earth station receiving antenna in the 4 kHz bandwidth may be used as a criterion for protection of the RNSS earth stations: 153 dB(W/(m2 4 kHz) in the 149.9-150.05 MHz frequency band; 156 dB(W/(m2 4 kHz) in the 399.9-400.05 MHz frequency band. Rec. ITU-R M.1470 3 1470-0143210 1234 5
17、 5 4 3 2 1 012340180170160150140130120110100909080706050403020101020304050607080140130120110100150160170FIGURE 1Transmitting antenna gain for the frequency150 MHz of the RNSS space stationNadir directionGmax= +3.5 dBAntenna gain (dB)FIGURE 1/M.1470.1470-01 = 18 CM 4 Rec. ITU-R M.1470 1470-023 2 1 0
18、12345 6 6 54 3 2 1 0 1 2 30180170160150140130120110100909080706050403020101020304050607080140130120110100150160170FIGURE 2Transmitting antenna gain for the frequency 400 MHzof the RNSS space stationNadir directionGmax= +3.0 dBAntenna gain (dB)FIGURE 2/M.1470.1470-02 = 18 CM Rec. ITU-R M.1470 5 TABLE
19、 1 Parameters of the existing RNSS system ANNEX 2 1 Methodology for estimating the effects of interference from the LMSS transmitting earth stations to the RNSS receivers The RNSS stations use the frequency bands 149.9-150.05 MHz and 399.9-400.05 MHz in the space-to-Earth direction and therefore int
20、erference could occur to receiving earth stations in the RNSS from MSS transmitting ground-based earth stations in the course of co-frequency operation of LMSS (Earth-to-space) and the RNSS stations in those bands. To estimate feasibility of sharing between LMSS earth stations (Earth-to-space) and R
21、NSS earth stations a method of determining the required coordination distances between LMSS transmitting earth stations and RNSS receiving earth stations could be used. Beyond those distances interference caused by LMSS transmitting earth stations to RNSS receiving earth stations may be considered a
22、cceptable. Within those distances, detailed calculation of interference is required. Parameter RNSS Orbital Number of satellites Altitude (km) Inclination (degrees) Orbit planes Satellite/plane Right ascension of ascending node (degrees) 7 1 000 83 7 1 0, 51, 103, 154, 206, 257, 309 Downlink Band (M
23、Hz) Tx power (W) Tx e.i.r.p. (dBW) Maximum Tx antenna gain (dB) Tx antenna pattern Channel BW (kHz) Rate (kbit/s) Polarization dSub Rx G/T (dB(K1) Maximum Rx antenna gain Rx antenna pattern 149.9-150.05 4.8 8.3 3.5 Fig. 1 0(1), 14, 127 0.05/FSK RHCP 200-400 0 Not determined 399.749-400.131 4.8 7.8 3
24、.0 Fig. 2 0(1), 22, 254 0.05/FSK RHCP 200-400 0 Not determined (1)Unmodulated carrier. 6 Rec. ITU-R M.1470 Required attenuation between a transmitting earth station in the LMSS and a receiving earth station in the RNSS may be estimated as: Lreq= (Pt+ Gt+ 36) Ir(1) where: Lreq: required attenuation b
25、etween a transmitting earth station in the LMSS and a receiving earth station in the RNSS (dB) Pt: maximum power spectral density for a transmitting earth station in the LMSS (dB(W/Hz) Gt: maximum antenna gain for a transmitting earth station in the LMSS (dBi) Ir: permitted interference level produc
26、ed at the RNSS earth station receiver input in a reference bandwidth of 4 kHz (dB(W/4 kHz). The required interference level at the input of an earth station receiver in the RNSS may be estimated as: Ir= ( pfd )r+ Sr= ( pfd )r+ Gr+ 20 log 10 log (4) (2) where: Sr: effective antenna surface area (dB(m
27、2) Gr: maximum antenna gain for a receiving earth station in the RNSS (dBi) : wavelength (m). The estimation results for Irare presented in Table 2. TABLE 2 Substituting Irvalues in equation (1) results in an opportunity to define required attenuation between a transmitting earth station in the LMSS
28、 and a receiving earth station in the RNSS as: for the frequency band 149.9-150.05 MHz: Lreq= (Pt+ Gt+ 36) + 158 (3) for the frequency band 399.9-400.05 MHz: Lreq= (Pt+ Gt+ 36) + 169.5 (4) In the case of land mobile earth stations, relationships between the required attenuation, Lreq, and the distan
29、ce, d, may be estimated using equations (5) to (8): for the frequency 150 MHz: Lreq= 86 + 20 log d + 0.0674 d for d 100 km (5) Lreq= 70.5 + 40 log d 0.178 d for 10 km 100 km), Fig. 4 (for 150 MHz and distance 10 km d 100 km), Fig. 5 (for 400 MHz and distance 10 km d 400 km), Fig. 6 (for 400 MHz and
30、distance 400 km d 700 km). 1470-03175170165160155150145140135130100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500Attenuation,Lreq(dB)Distance, d (km)Attenuation as function of distance (for 150 MHz and d 100 km)FIGURE 3FIGURE 3/M.1470.1470-03 = 10 CM 1470-04130125110120115105100135
31、10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100Attenuation,Lreq(dB)Distance, d (km)Attenuation as function of distance (for 150 MHz and 10 km d 100 km)FIGURE 4FIGURE 4/M.1470.1470-04 = 10 CM 8 Rec. ITU-R M.1470 1470-0510 40 70 100 130 160 190 220 250 280 310 340 370 40013012512014013515014
32、5160155170165180175115110Attenuation,Lreq(dB)Distance, d (km)FIGURE 5Attenuation as function of distance (for 400 MHz and 10 km d 400 km)FIGURE 5/M.1470.1470-05 = 10 CM 1470-06205200195190185180175400 425 450 475 500 525 550 575 600 625 650 675 700Attenuation,Lreq(dB)Distance, d (km)FIGURE 6Attenuat
33、ion as function of distance (for 400 MHz and 400 km d 700 km)FIGURE 6/M.1470.1470-06 = 10 CM For estimating the coordination distance between MSS gateway earth stations at specific locations and earth stations in the RNSS operating in the 149.9-150.05 MHz band, equation (9) may be used: Lreq= 69 + 4
34、0 log d + 30 log f 20 log (h1h2) + 10 log (0.02 p) (1 exp(0.1 d )2(9) Rec. ITU-R M.1470 9 where the attenuation must not be less than the free-space loss (dB) by: Lreq= 32.5 + 20 log d + 20 log f (10)where: p : percentage time for which the field strength will be exceeded, in the range 1 to 50%. In
35、this case, the appropriate value is 5% h1, h2: terminal heights (m) for the transmitting and receiving antennas, each having a minimum value of 1 m, with the product (h1h2) limited to 300 m2. In this case, the appropriate value for h2ranges from 5 to 60 m. For determining the coordination distances
36、for MSS gateway earth stations located at specific sites, the terrain clearance correction factor contained in Recommendation ITU-R P.370 (equation (3) may also be applied. The terrain clearance angle correction factor is a loss (dB) and can be expressed as follows: GfaGfbGf9GeaGebGe9Gf7Gf8Gf6Ge7Ge8
37、Ge6+= 1.01)1.0(log209.61.8factorCorrection2vv (11) where: 300/)950004( =v : angle (rad) between the horizontal at the transmitting antenna and the line which just clears all obstacles within 16 km in the direction of the receiver. is negative for angles above the horizontal. ANNEX 3 Methods which ca
38、n be utilized to facilitate sharing between LMSS (Earth-to-space) and RNSS in the frequency bands 149.9-150.05 MHz and 399.9-400.05 MHz Frequency band (MHz) Methods 149.9-150.05 and 399.9-400.05 Maintaining a coordination distance Using MES-controlled frequency avoidance techniques to avoid transmis
39、sion on the same frequency during periods of RNSS transmission in the same area Limiting minimum elevation angle for LMSS gateway earth stations with azimuth directed towards navigable waterways NOTE 1 It should be regarded that interference may occur between TSYKADA transmitters and LEO MSS spacebo
40、rne receivers. LEO MSS operators will have to understand that this interference may curtail their operations during spacecraft mutual visibility events. In addition MSS system operators must ensure that their spacecraft receivers are designed to accommodate strong interfering signals without damage.
