It is often recommended that FS characteristics are to be found in the Rec. ITU-R F.758-4 when FS frequency sharing with aircraft-mounted FSS Earth stations in the band 27.5-29.5 GHz is considered. Note that Rec. ITU-R F.758-4 has also been newly revised; the draft revision is currently in the final stage of being approved and publication of new version F.758-5 is expected soon. As specified in Annex 2 of its Section 4, the system parameters shown are not representative of any actual FS system, but represent an averaging or an expected range of values suitable for generic sharing/compatibility studies.
Stations FS5 and FS6 in the table 1 below have parameters in line with the Rec. ITU-R F.758-5.Also four other representative FS stations FS1, FS2, FS3 and FS4 can be proposed as given in in Table 1. FS1 and FS3 stations are representative of PP FS stations typically deployed, FS2 is representative of a longer than usual link operating in Scotland or Wales where the terrain is mountainous and hence an elevation angle of 5 degrees is appropriate, while FS4 is representative of a P-MP Hub station; P-MP subscriber stations are expected to have parameters similar to those valid for PP stations.
Antenna radiation patterns for FS-PP are usually assumed in sharing studies using the formulas in ITU-R F.699 (when a single FS system is considered as victim/interferer) or F.1245 (when averaging among a number of FS systems as victim/interferer). For P-MP it is recommended to use the ITU-R F.1336.
Table 69: Recommended FS characteristics for FS vs FSS studies
Parameter | FS1 (PP) | FS2 (PP) | FS3 | FS4 | FS5 (PP based on Rec. ITU-R 758-5) | FS6 (P-MP based on Rec. ITU-R 758-5) | Notes |
RX antenna height | 20 m | 20m | 20m | 20m | Not specified, 20m is suggested | Not specified, 20m is suggested |
|
RX antenna pattern | ITU-R | ITU-R | ITU-R | ITU-R | ITU-R Rec. | ITU-R | Source: |
Receiver noise figure, F | 6 dB | 6 dB | 6 dB | 6 dB | 8 dB | 8 dB | See note (1)[1] |
RX frequency | 28 GHz | 28 GHz | 28 GHz | 28 GHz | 24.25 – 29.50 GHz | 24.25 – 29.50 GHz |
|
RX elevation angle | 0° | 5° | 10° | 0° | Not specified, 10° is suggested | Not specified, 0° is suggested |
|
RX peak gain | 45 dBi | 43 dBi | 35 dBi | 18 dBi |
| 6.5 dBi
| See note (2)[2] |
The Spectrum Mask for P-P and P-MP can be found in EN 302 217-2-2 Annex A (table A4) and EN 302 326-2 (Section 5.3.4.1) respectively. Blocking information is available from EN 301 390 (Section 7).
With respect to antenna height for P-P, the BS and TS minimum antenna height are about 20 m and for P-MP, the BS minimum antenna height is about 20 m and the TS minimum antenna height is about 1.5 m.
For the antenna elevation, some countries reported an elevation range of 3 to 10 degree. Note that a range of maximum elevation angle from 15 to 30 degree has been reported in some countries in rare cases.
ECC Report 100 widely uses an I/N ≤ -10 dB; I/N ≤ -6 dB is there mentioned only for the protection of ENG/OB. FS systems (for both P-P and P-MP systems) commonly adopt I/N ≤ -10 dB as ITU-R SG5 has recently confirmed in the draft revision of Rec. F.758-4.
[1] The System noise power density shall be obtained from the following equation:
N0 (dBW/Hz)= F(dB) + 10*log10(kT0)
Where : T0 = 290 K, F is the noise figure and k is the Boltzmann constant it results:
N0 (dBW/Hz) = F(dB) - 204 (dBW/Hz) or N0(dBm/MHz) = F(dB) - 114 (dBm/MHz)
[2] The difference between the peak gain values of stations FS1 and FS2 comes from the fact that a typical PP FS station with high elevation angle (10°) is usually employed for short-range links near hilly areas.