INTERFERENCE MITIGATION IN CARRIER AGGREGATION IN 4G AND 5G USING DIGITAL PREDISTORTION TECHNIQUE

Abstract

In this thesis, different types of carrier aggregation techniques available in 4G and 5G is discussed briefly. Generation of all types of carrier aggregated signal is carried out along with discussion of design challenges of the terminal transmitting these aggregated carriers. The non-linearity of the power amplifier present on transmitter side is responsible for the interference in adjacent channels (in-band and out of band emissions). Digital Predistortion (DPD) technique has been applied to linearize this power amplifier to overcome this problem of interference. 1D-DPD and 2D-DPD technique has been applied in case of intra-band and inter-band carrier aggregation respectively. The performance analysis of DPD technique has been carried out by NMSE and ACPR table obtained after comparing power spectral density plots of the measured output through power amplifier and the overall linearized output. The effect of input power backoff on the distortions introduced by power amplifier has been also investigated by plotting ACPR and NMSE with relative input power backoff for all types of carrier aggregation