Impact of nonlinear power amplifier on the transmission of scalable multimedia contents
Résumé
The transmission of highly scalable image and video codestream over error-prone networks can be ensured by using Unequal Power Allocation (UPA) in MIMO-OFDM systems. However, UPA schemes are usually designed without taking into account the High Power Amplifier (HPA) nonlinearity, especially in MIMO-OFDM systems which are known to generate signals with a high Peak-to-Average Power Ratio (PAPR). This paper aims to evaluate the impact of HPA nonlinearity on the transmission of scalable image cotents over a precoded Closed-Loop MIMO-OFDM system when the well-known Content-Based Precoder (CBP) is used for UPA. For PAPR reduction, we have considered the Tone Reservation Using Null Subcarriers (TRNS) technique. Simulations are performed under the IEEE 802.11n standard in a realistic urban environment in presence of a commercial 2W class-AB memoryless HPA from RF Micro Devices. The experimental results in terms of Bit Error Rate (BER) and visual quality show that the error-protection of the most sensitive parts of the codestream against channel distortions achieved using UPA is significantly disturbed in presence of HPA nonlinearity. These results highlight the influence of HPA nonlinearity on the scalable image transmission.