· · · (1 | |/d )–1.4 · 10–TFM/10 P(hop outage) K d f hr – he 3.6 0.89 where: : geoclimatic factor K : link length (km) d : frequency (GHz) f and : transmit and receive antenna heights (metres above sea level or another hr he common reference) : thermal fade margin on a hop (dB). TFM where: unfaded carrier-to-noise ratio (C/N) (dB) : value of at which the performance criterion is just met (dB). CNC C/N Setting · · · (1 | |/d)–1.4 · 10–CNC/10 K d f hr – he γ 3.6 0.89 Then: · /C P(hop outage) γ NT Thus · /C P(hop outage before satellite interference) γ NT · (NT )/C P(hop outage aggregate satellite interference) I γ where and are in consistent power units. C, NT I If it is assumed that: each hop is designed to have a similar nominal probability of outage before satellite – interference; hop fades are independent and sufficiently rare that the outage probabilities may be added, – then the net nominal probability of outage for the route is: (P(hop P(route outage) outage))number Σ of hops in route Thus, the fractional increase in the probability of a route outage due to a degraded fade margin on each hop within the route is simply: FDP(route outage) i.e. the route FDP is the total route interference power divided by the total route noise power: Thus the FDP approach for the assessment of the impact of interference on a FS route and the usage of percentages (rather than dB) is appropriate.
P(hop outage) K · d 3.6 · f 0.89 · (1 | hr – he |/d )–1.4 · 10–TFM/10 where: K : geoclimatic factor d : link length (km) f : frequency (GHz) hr and he : transmit and receive antenna heights (metres above sea level or another common reference) TFM : thermal fade margin on a hop (dB). where: unfaded carrier-to-noise ratio (C/N) (dB) CNC : value of C/N at which the performance criterion is just met (dB). Setting K · d 3.6 · f 0.89 · (1 | hr – he |/d)–1.4 · 10–CNC/10 γ Then: P(hop outage) γ · NT /C Thus P(hop outage before satellite interference) γ · NT /C P(hop outage aggregate satellite interference) γ · (NT I )/C where C, NT and I are in consistent power units. If it is assumed that: – each hop is designed to have a similar nominal probability of outage before satellite interference; – hop fades are independent and sufficiently rare that the outage probabilities may be added, then the net nominal probability of outage for the route is: P(route outage) Σ (P(hop outage))number of hops in route Thus, the fractional increase in the probability of a route outage due to a degraded fade margin on each hop within the route is simply: FDP(route outage) i.e. the route FDP is the total route interference power divided by the total route noise power: Thus the FDP approach for the assessment of the impact of interference on a FS route and the usage of percentages (rather than dB) is appropriate.
R-REC-F.1107-2-201105-I!!MSW-E.docx