Page 259 - GuideFWA

3. IN ANY OF ABOVE CASES, THE RESULT FOR INTERFERING SIGNAL WILL BE,
AT LEAST, 15 dB LOWER, BUT PROBABLY HIGHER DIFFERENCE WOULD BE
OBTAINED, AND JUST ONLY FOR THIS CORRECTION.

• The TX power values for DECT described used in table 1 of document [20] are wrong. The
nominal transmission power for DECT, FOR ALL SCENARIOS, is equal to 24 dBm (as
used in report [1]).

• The values assumed for traffic density in Business and Residential areas are excessive (as
already explained in section 1b. of the current document). It is likely than the real values for
this parameter will be about 5 to 10 times lower than the expressed ones in [20], specially
taken into account that such proposed traffic values can not be applied in areas with 5, 10 or
15 Km. or radius from the victim receiver, as used in graphics of [20].

• The provided graphics seems not to take into account the probability of having “m”
simultaneous transmissions (i.e., probability given by equation 2.4). As a example of the
effect of this equation see the following:
- Assume a traffic density of 150 Erl/km2 for business area as stated in [20]
- Assume antenna beam-width of 90º for DECT as stated in [20]
- Assume antenna beam-width of 105º for PCS BS as stated in [1]
- Assume a value of r=20 m., as stated in [20]
- Assume a value of R=1 Km. as one proposed in [20]
- With N=120 DECT channels, the value of K, as stated in equation 2.3 of [20] will

be equal to K = 0.29
- With this value of K, the equation 2.4 of [20] gives the following probabilities:

¾ P(0) = 75.11 % = probability of having 0 !! transmissions
¾ P(1) = 21.50 % = probability of having only 1 transmission
¾ P(2) = 3.08 % = probability of exactly 2 simultaneous transmissions
¾ P(>2) = 0.31% = probability of > 2 simultaneous transmissions
- Thus the MOST PROBABLE CASE (75.11%) IS THAT THERE IS NOT ANY
INTERFERING TRANSMISSION, which is a complete different information than the
one shown in graphic 3.1 of [20].

• The calculations in [20] do not take into account several relevant radio parameters which
have been taken into account in [1], such as: Losses due to vertical radiation pattern of
antennas (which could be very high, specially in short distances), losses due to horizontal
radiation patterns (even when both antennas are on-beam, there could be up to 6 dB of losses,
3 dB per antenna TX and RX. In [1] it was assumed 1+1 dB, for this reason), feeder losses,
in-band reference bandwidth for emission masks, Receiver sensitivity of the victim device,
C/I ratio of the victim system, etc.

• The values of noise floor for PCS IS-95 BS and PCS IS-136 BS given in [20] are not agreed
by Experts Group. Moreover, in the calculation of rise in the noise floor, made in [20], it had
not taken into account properly the internal interference of the own PCS system. This is the
reason for the excessive values of rise in the noise floor given in the paper [20]

• It is mentioned in [20] that “if WRS is used to relay the signals between FP and CTA or PP,
the number of transmissions K calculated in (2.3) should be doubled”. This statement is
false, since the use of WRS is just to cover special areas where normally BS transmissions do
not cover (or it is desired to not be covered due to traffic considerations), and then, the total

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