Spurious Interference and Blocking Interference for LTE
Spurious interference refers to the additive interference generated by the interference source in the working frequency band of the interfered receiver. Spurious interference includes the out of band power leakage of the interference source, amplified background noise, and transmit inter-modulation product. Spurious interference can reduce the signal noise ratio (SNR) of the interfered receiver.
Spurious interference is generated by a transmitter and usually includes the thermal noise generated and amplified by the power amplifier (PA). Inter-modulation products can be generated during the multi-carrier operation and spurious signals can also be generated by frequency mixer.
Receivers usually work in linear areas. When a strong interference enters a receiver, it may also overdrive the receiver to work in non-linear state or even worse, in saturation mode as the out of band suppression ratio of the receiver may be limited. This type of interference is called blocking interference.
Generally, blocking interference is generated by a strong interference signal out of the receive band that makes the receiver work in saturation state and then reduces the gains. In addition, the interference signal may mix with the local oscillator signal and then generate the interference in the intermediate frequency (IF). Blocking interference can reduce the receiver gains and increase the noise.