Estimation method for RF signals distortion caused by IQ-asymmetries, requires using sub-carriers arranged symmetrically to one another in transmission spectrum

摘要

A method for estimating the distortion of radio (RF) signals as caused by IQ-asymmetries, the RF signals being transmitted in data blocks in a multi-carrier transmission procedure, specifically an OFDM-procedure, and using sub-carriers n, and -n arranged in the transmission spectrum symmetrically to n, relative to a center frequency fc. Each data block contains two reference data symbols (T1,T2) , and during the reference data symbols (T1,T2) relative to each pair of sub-carriers n/-n the transmitted data symbol is constant in time on one sub-carrier, while on the other sub-carrier the sign changes, and the distortion parameters are calculated from the received sub-carrier symbols. Independent claims are given for an application (A) of a method in a direct mixing receiver and (B) in a heterodyne receiver with direct mixing second stage.