Multiple lookup table predistortion for adaptive modulation

Abstract

This paper presents a multiple LUT digital adaptive predistorter based on a Hammerstein model that uses the return channel to feed back information from the receiver, concretely the bit error rate (BER), in order to train and later adapt the specific LUT gains that permit always operating at the best back-off level. This new predistorter architecture is aimed at coping with modern communication standards that use adaptive modulation (such as IEEE 802.11 or IEEE 802.16) and therefore continuously searching the best linear amplification to maximize power efficiency at the time that a certain quality of service (BER) in reception is guaranteed. Simulations provided will show the advantages of this multi-LUT configuration, where in front of different channel conditions, linear and efficient amplification (minimum back-off) is achieved at the time that a certain level of BER at reception is ensured. Index terms – Lookup tables (LUT), digital adaptive predistortion, Hammerstein models, adaptive modulation systems, peak to average power ratio (PAPR), bit error rate (BER).