AN UNEQUAL POWER ALLOCATION DESIGNED FOR MIMO SYSTEMS USING CONTENT CHARACTERISTICS
Résumé
This paper presents an Unequal Power Allocation (UPA) strategy for the transmission of a JPEG 2000 Wireless (JPWL) 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 four other precoders of the literature such as Water Filing (WF), Minimum Mean Square Error (MMSE), Minimum Bit Error Rate (MBER) and Equal-dmin (E-dmin). Indeed, we show that power allocation of these precoders is not suitable 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 our proposed approach improves the visual quality. We also present a study highlighting the good robustness of the algorithm to channel estimation errors.