| A new HPA model and four new techniques to compensate the distortions caused by the nonlinearity of the HPA, used in wireless communication systems, are proposed and analysed in this thesis. The proposed HPA model is based on rational functions with complex coefficients and only one function is used to represent both AM-AM and AM-PM conversions. Two, out of the four compensation techniques proposed, are predistortion techniques where the input signal of the amplifier is operated on to achieve the compensation. The other two techniques fall into the category of post-compensation techniques at the transmitter due to the fact that the compensation is applied on the output of the HPA before the antenna transmits it. One of the techniques performs amplitude and phase compensation separately and is based on existing models of the HPA AM-AM and AM-PM conversions. The rest of the techniques are based on the proposed HPA model, and amplitude and phase compensation is achieved jointly. |
