An Unequal Power Allocation Designed For JPWL Transmission Over MIMO Systems
Résumé
This paper presents a Joint Source Channel Coding strategy for the transmission of a JPWL (ISO/IEC 15444-11) image. To ensure the Quality of Service (QoS), we exploit the channel diversity with a Closed-Loop MIMO scheme. It relies on the Channel State Information (CSI) knowledge at the transmitter side that diagonalizes a MIMO channel into several hierarchical SISO subchannels. In the proposed scheme, the JPWL codestream is divided into hierarchical quality layers passing through the SISO subchannels. According to this strategy, we propose a new content-based precoding algorithm to maximize the visual quality in reception. This algorithm is compared with the Minimum Mean Square Error (MMSE) precoder that minimizes the mean square error in reception. Indeed, we show that a power allocation based on Lagrangian optimization (case of MMSE precoder) is not adapted to ensure QoS of a hierarchical content. We compare precoders' performances on a statistical channel and a realistic time-varying MIMO channel provided by a 3D-ray tracer propagation model. Results show that the proposed approach improves the visual quality.