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The interfering Received Signal Strength (iRSS), corresponding to the interference level (I), is calculated as a link budget between the VLR and the interfering link transmitter (ILT) as described in ANNEX 5:. The various interference mechanisms resulting in d...

When the bandwidth of the interferer and the victim are different, SEAMCAT automatically applies a bandwidth correction factor to calculate the unwanted emission power for a specific bandwidth. The following example introduces an interferer transmitting 2 W. T...

Desensitisation (D) of the receiver in the presence of an interfering signal, given in dB, corresponds to the ‘noise rise’ or ‘noise augmentation’ due to the interfering signal and is derived by the following equation in dB:                                    ...

The term “Blocking” is used in SEAMCAT to describe the capability of the victim receiver to receive a wanted modulated signal without exceeding a given degradation due to the presence of an unwanted input signal on a different frequency than the one of the wan...

The receiver selectivity is often given as Adjacent Channel Selectivity (ACS) – i.e. when the concept of "channel" has been defined for the system being considered. As the wording suggests, this parameter defines the requirement in case one single ILT is set a...

In-band emission is understood as relating to the necessary bandwidth. The ITU-R Radio Regulations define the followings in Nos. 1.152, 1.144, 1.145 and 1.146: 1.152 Necessary bandwidth: For a given class of emission, the width of the frequency band which is j...

A co-channel interference scenario can be illustrated as shown in figure below. In this case a part or the whole component of the interference is within the receiver bandwidth of the victim receiver. Figure 4: Co-channel interference scenario

The statistical methodology used as a basis for SEAMCAT is the Monte Carlo method. Statistical simulation methods may be contrasted to conventional analytical methods, which are typically applied to ordinary or partial differential equations that describe som...

In this section the interference calculations for ‘generic’ systems are described. Cellular systems (OFDMA and CDMA) use a different interference calculation method based on throughput and capacity loss which are described in more detail in ANNEX 15:

The C/I ratio available at the victim receiver’s input is computed using both the iRSS (Interfering Received Signal Strength) and the dRSS (desired Received Signal Strength),. Figure 7 illustrates the various signal levels used to determine whether or not inte...

Four interference criteria are considered within SEAMCAT: C/I         : Carrier to interference ratio; C/(I+N)   : Carrier to interference plus noise ratio; (N+I)/N   : Desensitisation; I/N         : Interference to noise ratio.   All of these criter...

C/I may vary typically from 9 dB (e.g. for QPSK) to 26 dB or higher (e.g. for 64QAM…). By introducing artificial noise iRSS on top of the noise floor (I/N), C/I is then desensitised by (N+I)/N resulting in C/(N+I). Note that the desensitisation is exactly the ...

The level of unwanted emissions  ( i.e. consisting of the out-of-band emissions and the spurious emissions [8] of the ILT) falling within the VLR receiver bandwidth (Figure 11) is determined using the interferer’s transmit mask, the receiver bandwidth of the V...

The level of interference determined by the interferer’s transmit power, the antenna gains and propagation loss, is further decreased due to the receiver blocking performance for a given interferer/victim frequency separation. Details on the iRSSblocking calcu...

The intermodulation interference, i.e. the power of intermodulation products, reduced by the intermodulation attenuation function of the VLR can be used in interference calculations. See ANNEX 5: for further details.

Overloading threshold is the minimum interfering signal levelat which the receiver loses its ability to discriminate against interfering signals at frequencies other than that of the wanted signal. See Annex A2.2 for the use of overloading in interference calc...

The combination of the unwanted emissions and receiver blocking can also be studied simultaneously in SEAMCAT as depicted in Figure 13. See Annex A2.3 for further details. Figure 13: Illustration of the combined unwanted emissions and the receiver blocking me...