A Simplified DPD Linearizer using Operation Point Estimation Pilot Signals for Mobile Terminal Application in TDD Wireless Systems

Mobile terminal is required to improve the power utilization efficiency of HPA (High Power Amplifier) since the uplink transmission rate will increase and millimeter-wave band will be widely utilized in B5G (Beyond 5G). Small OBO (Output Back Off) operation of HPA improves power utilization efficiency however ACLP (Adjacent Channel Leakage Power) increases due to HPA nonlinearity, and it degrades spectrum efficiency. To solve these two problems, this paper proposes a simplified DPD (Digital Pre-distortion) linearizer for mobile terminal application in TDD (Time Division Duplexing) wireless systems. Key advantage of the proposed DPD linearizer is that it does not need an auxiliary receiver for DPD control, but it estimates DPD operation point by using multi-carrier pilot signal. This paper describes design methodology of operation point estimation pilot signals using Babcock frequency allocation and shows evaluation results of DPD operation point estimation accuracy as well as ACLP and ACI improvement performance by computer simulations.