Aiming at the problem of low quality of video viewing experience in dynamic network environment with limited cache capacity, a Dynamic Adaptive Step-wise Bitrate Switching (DASBS) algorithm for HTTP streaming considering network bandwidth and cache capacity was proposed. Firstly, a sliding window was used to analyze the recent downloaded fragments, obtaining the initial bandwidth estimation. Then, according to the real-time bandwidth fluctuation degree and cache state, two correction factors were set to further smooth the bandwidth estimation. Finally, a cache threshold was set to establish a correlation with the current bitrate, and the bandwidth estimation and the cache dynamic threshold were used to jointly control the bitrate switching. Experimental results on platform libdash show that DASBS is better than Video Quality Control for QoE (VQCQ) algorithm in switching smoothness and its average bitrate of video playback is higher, which effectively improves the bandwidth utilization. Although the average bitrate is slightly lower than that of Evolution of Adaptive Bitrate Switching (EABS) algorithm, the number of switching times is greatly reduced, improving the switching stability. The experimental results show that the proposed algorithm has high bandwidth utilization, switching smoothness and switching stability in dynamic network environment, which can effectively improve user experience.

Focusing on the issues of low efficiency, being easy to be influenced by subjective factors and deviation of the evaluation results caused by the traditional edge quality evaluation which relies on experts, a new mapping evaluation operator called Geographical Mapping Operator (GMO) was proposed. Fuzzy comprehensive evaluation was applied to the edge quality evaluation, and the comment rate and evaluation index were determined according to the national standard, as well as the fuzzy weight vectors of evaluation factors were determined through the entropy weight method. Besides, the new operator was proved by theory. When applying the GMO to the actual data, the unqualified quality of earth data accounts for 65% before edging, but the perfect quality of earth data accounts for 55% after edging, which indicates the effectiveness of GMO.

Hardware/Software (HW/SW) partitioning is one of the crucial steps in the co-design of embedded system, and it has been proven to be a NP problem. Considering that the latest work has slow convergence speed and poor solution quality, the authors proposed a HW/SW partitioning method based on greedy algorithm and Simulated Annealing (SA) algorithm. This method reduced the HW/SW partitioning problem to the extended 0-1 knapsack problem, and used the greedy algorithm to do the initial rapid partition; then divided the solution space reasonably and designed a new cost function and used the improved SA algorithm to search for the global optimal solution. Compared to the existing improved algorithms, the experimental results show that the new algorithm is more effective and practical in terms of the quality of partitioning and the running time, and the promotion proportions are 8% and 17% respectively.

Elastic scheduling is designed for real-time systems with variable load. It adjusts the task attributes dynamically to meet the flexibility requirements of system, and it is an effective task scheduling strategy. Concerning the research results and problems of elastic scheduling, an overview of elastic scheduling was given out, and the research progress of the elastic periodic task model, scheduling model and the elastic scheduling algorithm were analyzed. The existing problems in research were investigated, and possible research areas in future were suggested.

To decrease the storage space and improve the search velocity of CRL(Certificate Revocation List),a bit pointer was used to shorten the certificate number of it.And a new certificate recocation tree was proposed,which could keep the good properties of CRT(Certificate Revocation Tree) that is easy to check or prove whether a certificate is revoked or not,the check only need the related path values but not the whole CRT values.The new tree also could overcome the disadvantage of CRT that any update will cause the whole CRT to be computed,so it accelerate the speed of the CRT update.

The architecture of software and hardware of the embedded CAN-Ethernet gateway were introduced, and the principle, the designing methods and technoloques of the CAN Device Driver in uClinux were described. According to the features of the CAN protocol, data package was classified into four groups with different real-time request; the structure of multi-frame was proposed to satisfy the request of sending mass data; the data structure and the method of management for the buffer of the CAN Device Driver were designed to improve the capability of communication.