Cesson-Sévigné, France
Cesson-Sévigné, France

Time filter

Source Type

Cheaito A.,INSA Rennes | Helard J.-F.,INSA Rennes | Crussiere M.,INSA Rennes | Louet Y.,IETR CentraleSupelec
Proceedings of the International Symposium on Wireless Communication Systems | Year: 2016

In this paper, we analyse the impact of clipping used as a peak-to-average power ratio reduction technique for multicarrier signals, assuming that a linearization stage is implemented before the power amplifier. Therefore, the expression of the Error Vector Magnitude (EVM) of the output signal is analytically derived. We mainly focus on the effect of clipping in both cases with and without the use of the predistortion stage. We provide analytical expressions of the EVM in the form of a series expansion that depends on the clipping threshold, the transition factors of the power amplifier, the predistortion characteristics and the PAPR of the input signal. We show through simulations that the proposed expressions present very good accuracy, even when limiting the series expansion to an order of 4. Finally, a simple scenario is proposed to demonstrate the benefit of our EVM expressions in controlling the average transmitted power with the aim to guarantee a high quality of service. © 2015 IEEE.


Cheaito A.,INSA Rennes | Crussiere M.,INSA Rennes | Helard J.-F.,INSA Rennes | Louet Y.,IETR CentraleSupelec
Proceedings - IEEE INFOCOM | Year: 2016

The high Power Amplifier (PA) dominates the power consumption in LTE transceiver systems in macro base stations and requests focusing the energy efficiency improvements on this device. In this paper, the impact of the nonlinearities on the amplified multicarrier signal is analyzed considering both linearization and Peak-to-Average Power Ratio (PAPR) reduction techniques. Therefore, we provide the expression of the Error Vector Magnitude (EVM) of the amplified signal using polynomial predistortion and clipping techniques. The EVM expression is a series expansion that depends on the Power Amplifier (PA) and predistortion coefficients, as well as, the PAPR and the average power of both input and clipped signals. The simulation results show that the proposed expression presents perfect accuracy. Moreover, theoretical analysis of the trade-off between the power amplifier linearity and efficiency is investigated considering the performance of the clipping and predistortion techniques. Therefore, an analytical expression which gives the optimal Input Back-Off (IBO) maximizing the PA efficiency, with respect to an EVM constraint and a given predistortion complexity, is provided. Based on different application scenarios and using a real power amplifier characteristic, it is demonstrated that significant energy efficiency improvement can be achieved when the IBO is appropriately adjusted. © 2016 IEEE.

Loading IETR CentraleSupelec collaborators
Loading IETR CentraleSupelec collaborators