Research On Cross-Layer Bandwidth Allocation In Satellite Communication System And Multimedia Communication Technology

With the development of information and communication technologies, modern satellite communication system can provide broadband high-speed services, including high-definition video, image, interactive services and high-speed data services.As a new kind of technology, cross-layer design can efficiently improve utilization of system resources, ensure communication performance and QoS, and has become a hot research topic in the next generation of satellite communications.Meanwhile, satellite communication system is vulnerable to rainfall and other weather factors, resulting in the phenomenon of error video frames, and seriously affects the quality of communication. Therefore, the studies on error concealment (EC) technique for H.264/AVC video in a broadband multimedia satellite system and design of high-performance hardware architecture are very meaningful.In this paper, key technologies of standards for broadband satellite communication system, cross-layer-based resource allocation algorithms in broadband satellite communication system, and adaptive intra-frame error concealment algorithms for H.264/AVC video over satellite are firstly studied, and then deblocking filter and CAVLC decoder for H.264/AVC video are designed. The main innovative points and research works of this paper are described as follows:1. A review of DVB-RCS and DOCSIS-S standards on broadband satellite networks and the main specifications of standards are provided. And then the advantages of DOCSIS-S against DVB-RCS have been analyzed based on a comparison of the physical layer technology, IP networking methods and QoS guarantee.2. A cross-layer network utility maximization (NUM) resource allocation algorithm based on Data over Cable Service Interface Specification-Satellite (DOCSIS-S) protocol is proposed for broadband Geostationary Orbit (GEO) satellite communication networks. In order to fairly and efficiently distribute resources, the cross-layer NUM bandwidth allocation algorithm in media access control layer (MAC layer) is designed considering the physical layer (PHY layer) status and quality of service (QoS) requirements of the application layer (APP layer). The spectrum efficiency and fairness of the proposed solution are simulated and analyzed. It is shown that the proposed scheme can enhance the system spectral efficiency and the fairness between satellite terminals.3. A Novel Adaptive Intra-frame Error Concealment (NAIEC) algorithm for H.264/AVC video is presented. The proposed algorithm can solve the problem of packet loss during the transmission of video in the error-prone satellite channel. Firstly, the content of each lost block is classified into one of three categories according to the edge feature in local video. Then Bilinear Interpolation (BI), Directional Interpolation (DI) and Novel Directional Weighted Interpolation (NDWI) schemes are adaptively selected as the interpolation method to improve reconstructed video quality and speed up the concealment. Objective evaluation shows that a PSNR improvement of up to about3.2dB with negligible decoding time increment can be obtained. Subjective comparison shows that our proposed algorithm can achieve higher visual quality. 4. Based on the study and analysis of the basic filtering order and previously presented filtering orders, we put forward a competitive filtering scheme to reduce the filtering cycles and improve the system throughput. Then, a highly parallel and pipelined deblocking filter architecture is proposed accordingly. In the proposed system, two parallel filtering cores, three RAMs and several transposed arrays are used to simultaneously filter the horizontal and vertical edges.The proposed IP architecture is designed by Verilog HDL and implemented using TSMC0.18μm CMOS standard cell-based library. Comparison of various DBF solutions shows that the system performance of our proposal significantly outperforms the previous designs from3.7to8.3times. Moreover, our architecture can easily support real-time deblocking of60fps HDTV video, and it can be suitably integrated into the H.264/AVC decoder.5. A low power multisymbol structure of CAVLC (Context-based Adaptive VariableLength Coding) decoder customised for H.264/AVC baseline profile is presented. The dependency property of CAVLC algorithm limits the usage of parallelism and pipelining techniques, but other techniques such as table partitioning and multisymbol are adopted to decrease power and increase throughput. A top-level CAVLC architecture is proposed first and then its subdecoders are designed and analysed. Finally, the proposed CAVLC decoder is implemented in a0.18μm CMOS technology. The estimated area and power consumption are14873gates and14.46mW, respectively. The critical delay time is only5.59ns when the decoder is operating at167MHz. The proposed low power multisymbol CAVLC decoder can be suitably applied in H.264/AVC decoding systems.