9Out-of-band interference

9 Out-of-band interference

(1) Out-of-band interference is difficult to predict, because the levels and frequencies of unwanted emissions depend on both the nearness and the operating frequencies of radiocommunications transmitters and radiocommunications receivers that are spectrally or geographically close. In addition, out-of-band interference: (a) can extend for many MHz either side of the frequency boundary of a spectrum licence; and (b) is dependent on the quality of the radiocommunications receiver as well as the levels of the radiocommunications transmitter’s emissions; and (c) is difficult to model accurately. (2) Emission limits are also used to manage out-of-band interference, but these do not provide protection along the frequency boundaries of a spectrum licence throughout the entire geographic area. Because of the nature of out-of-band interference, emission limits cannot be used to provide protection from out-of-band interference for radiocommunications devices that are located near each other.

Note: Example: Radiocommunications devices that are located near each other include devices located at multi-operator sites.

(3) Emission limits are not the sole mechanism used to manage out-of-band interference for radiocommunications devices in close proximity, because the interference modelling inaccuracy would require large probability margins to be added to those limits. Large probability margins would place severe constraints on the use of the spectrum because the upper and lower frequency limits of a spectrum licence extend throughout the geographic area. Emission limits to manage out-of-band interference throughout the geographic area cannot be used, because they would lead to a severe loss of utility of the spectrum on both sides of the frequency limits. (4) To avoid large probability margins, out-of-band interference is managed through interference management procedures based on a compatibility requirement for radiocommunications receivers. A minimum level of receiver performance is specified in Part 4 in conjunction with the compatibility requirement because the performance level of receivers: (a) affects the level of interference; and (b) can vary for receivers operating under spectrum licences.

Note: The minimum level of receiver performance is specified in Part 4. The compatibility requirement is set out in Part 5.