OFDM Wireless LANs: A Theoretical and Practical Guide

Adaptive Predistortion Techniques

Heretofore, the adaptive techniques presented have been receiver algorithms. These techniques were derived to mitigate the noise associated with clipping. Herein, we consider adaptive techniques at transmitter or adaptive predistortion algorithms. The first technique reviewed, developed by H. Kang et al in [14], considers a predistortions algorithm for a cascade of HPA and linear filter. In the approach, the memoryless HPA preceded by a linear filter, as shown in Figure 5.17, is modelled as a Wiener system [11]. Precompensation is achieved via adaptive algorithm derived using a stochastic gradient decent method [11].

Figure 5.17. A simplified block diagram of the baseband equivalent OFDM transceiver. © 1995 IEEE. ...