In communications systems, in particular in wireless radio systems, co-channel interference (CCI) and carrier frequency offset (CFO) are well-known effects which degrade the quality of the received signal. CCI is caused by an interferer signal having substantially the same carrier frequency as a user signal to be detected. Typically, CCI suppression is accomplished by filtering the received signal with an appropriate filter structure.
CFO can be present in the user signal or the interferer signal or in both signals. CFO causes CCI suppression to deteriorate quickly with increasing distance from a training-sequence in the transmitted signal, leading to a decrease in signal quality. Typically, CFO compensation is done by measuring CFO and correcting the received signal by the measured frequency offset. CFO compensation is used for carrier frequency tracking.
The efficiency of CFO compensation depends on the CFO measurement equipment and on the algorithm and mathematical procedure for calculating the CFO correction quantity to be applied for signal frequency correction.