Page 210 - GuideFWA

- The majority of RXs (typically terminals) are working over the “Mean RX power” (i.e. with
fading margin included). Only at cell edges, fade could cause problems in terms of C/I ratio
(by definition 50% of time), but there it is very likely that a simple handover could solve the
problem. Note that a normal deployment of a PCS or FWA system tries to overlap the cells in
order to avoid this “bad” power budget at the cell borders.

- The probability of 50% is only defined and applicable for the cell edges areas and mainly
applicable to receiver terminals (i.e. mobiles) located within this small area. Base Stations
are not normally affected by this constrain (except for some very few call connections in
extremely bad conditions).

- The 50% of RXs in this “unfavourable situation” at the cell edges is translated to a much
lower percentage of RXs over the complete population of RXs within the cell coverage, and
then this “bad” situation does not affect to the 50% of the total RXs, but a much fewer
percentage of them. Additionally, the overlapping of cells also decrease this percentage up to
a value that can be considered insignificant.

Maybe it will exists more reasons, but, for me, it is enough with the above ones. […]

I think that we all agree that we should normally analyse the interference in a worst case basis.
However, this “worst case” analysis should always contains certain intuitive possibility to be
also a “enough probable case”. This methodology’ approach has been systematically applied
for all our reasoning and this is the reason why we have included in our analysis, for example,
the possibility to have TX and RX antennae on-beam or off-beam (the worst case of analysis is to
consider only both TX and RX antennae “on-beam” but we agreed that is not the most likely
situation). Many other assumptions has been agreed under this “enough probable case”
approach.

If we remove Fading Margin from our calculation we are not respecting this “enough probable
case” rule, because we are putting our analysis in a case that is more than a “worst case”, it
will be a “quasi-impossible case” since the probability weights will be continuously decreasing
up to a completely negligible value, and then, What are the applicability of calculated required
distances? […]”

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