A8.1 BASIC CONCEPT

The receiver captures capturing some unwanted signals outside its own channel bandwidth because its filter is not ideal.

Figure 382: Illustration of the non-ideal receiver filter with respect to an ideal
interfering link transmitter

 For generic systems, SEAMCAT provides three modes of considering the impact due to blocking (see Section 4.2):

1. User-defined:the values of the blocking mask are expressed directly as a Blocking response (filter selectivity) in relative positive values (dB) (see Figure 12);
2. Protection ratio:
   the values of the blocking mask are expressed in relative positive values (dB);
   SEAMCAT considers the underlying protection criterion applied by the measurement procedure of used in typical standards when calculating the resulting blocking response
3. Sensitivity:
   the values of the blocking mask are expressed in absolute power levels (dBm);
   SEAMCAT considers the underlying protection criterion applied by the measurement procedure used in typical standards when calculating the resulting blocking response

For cellular systems, if blocking is spsecified as ACS (Adjacent Channel Selectivity), then it is effectively the same as the User-defined mode for generic systems.

In all cases SEAMCAT perceives receiver blocking as a mask, which is a function of frequency separation between interfering and desired signals Δf=(f_ILT-f_VLR), however you may also specify a constant value of blocking across the whole frequency range.

Figure 383: Blocking

When calculating the value iRSS_blocking, SEAMCAT applies the obtained receiver attenuation value a_VLR to the full power of the interfering signal and will consider the resulting power (interfering signal at receiver input less blocking attenuation) as in-channel noise floor increase of the VLR.

In practice, SEAMCAT integrates the interfering signal captured by the receiver, excluding the part of the interfering signal falling into the necessary bandwith of the receiver[1]). For this integration, both the bandwidth of the interferer and the bandwidth of the victim are taken into account.