多媒体无线通信服务质量QoS研究
文献类型：学位论文
| 作者 | 翁莹 |
| 学位类别 | 博士 |
| 答辩日期 | 2005 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 中国科学院声学研究所 |
| 关键词 | 多媒体无线通信 服务质量QoS 群集轮询 非对称完全服务 离散余弦变换 快速视频流提取 指数退避 重传截断 |
| 其他题名 | Study on Quality of Service in Multimedia Wireless Communications |
| 中文摘要 | 随着多媒体业务的迅速发展，在无线通信中将扮演重要角色。但目前多媒体无线通信服务质量QOS还存在着种种不如意之处，单凭现有技术不足以满足人们的需求。于是就必须要有新兴技术来作为保证，因此对多媒体无线通信服务质量QoS关键技术进行研究具有极其重要意义。本论文的创新成果主要包括：（l）提出一种新的、在无线多跳网络中、支持混合多媒体通信业务流QoS的自适应群集聚类、分布式无线链路控制分享、分组轮询调度、离散时间非对称完全服务策略模型。基于嵌入Markov链、利用概率母函数方法、排队理论和利托氏定理对系统进行了定性和定量的分析研究，得到了系统的一阶和二阶特性，推导出每类群集移动用户的平均缓冲器容量和平均时延的精确解析式，并且对系统进行了分析和评价。此外，相关可变参数对系统特性的影响也进行了讨论和比较。通过模拟实验验证了理论分析的正确性。（2）提出三种新的、低时延、低代价、低复杂度、低功耗视频流像素快速提取算法，可以直接从MPEG压缩域（DCT域）提取视频流，而不需要进行完全的解压缩IDCT，其优势在于有着非常低的计算代价，满足了便携式移动设备对支持多媒体业务的Qos所要求的低功耗的处理器和显示端，使得能够在DCT域对于压缩视频流进行高速有效的和低代价的内容访问，为快速内容分析、对象提取、分割和交互操作，多媒体应用和服务方面提供了强有力的算法支持，并为像素域和压缩域之间的鸿沟架起了桥梁。同时还进行了广泛深入的海量实验。根据视觉感知和目检，以及根据直方图度量，均表明：提取得到的视频流帧保持内容完好，并且获得了近似于解压缩图像的极具竞争性的服务质量QoS，有着可接受的图像视觉感知质量。所提出的三种新算法也适用于JPEG压缩静止图像。（3）提出一种新的改进型Window-based截断指数退避冲突分解算法，在对新算法的工作原理进行分析后，给出了其算法数学描述式，并进行计算机模拟仿真实验。通过对改进型Window-based截断指数退避冲突分解算法和原有的截断指数退避冲突分解算法进行性能分析，比较，得出了改进算法的优点与不足。（4）对信息分组重传限制为一有限数值并且允许放弃信息分组的因子为r的指数退避和重传截断的有效联裔机制的通用情况本身的特性进行了深入研究。提出一种新的、简单但更精确的基于Markov链的无限站点二维离散时间分析模型，反映指数退避重传截断联合机制的实际运行情况。还进行了性能分析，推导出新的、更精确的解析结果，并且也给出了最大饱和吞吐量的解析表达式。模拟仿真实验结果验证了理论分析的正确性和此Markov链分析方法的有效性。还在系统负载和最小初始竞争窗不同的情况下，讨论了信息分组的放弃率。 |
| 英文摘要 | Quality of Sevice (QoS) will be more important in wireless communications in pace with the rapid progress of multimedia services. However there are some defects of QoS in multimedia wireless communications now, thus the present techniques cannot meet the new demands. Then the spring-up techniques are necessary, so it is very meaningful to carry out a research into the core techniques for QoS in multimedia wireless communications. The innovative contributions of this thesis are mainly included: A new multihop, providing support for QoS in heterogeneous mix of multimedia traffic, adaptive self-organizing clustering, distributed controlled sharing of the wireless link, packet scheduling polling, discrete-time with asymmetric exhaustive service policies network architecture is developed. By imbedding Markov Chain, the Probability Generating Function, queuing theory and Little's law, the qualitative and quantitative analysis is performed. The first and second order characters of this system are derived, and the exact analytical expressions of average buffer size and mean queuing delay are obtained. Then the performance of this system is analyzed and evaluated. In addition, how the relative variable parameters effect on system characteristics is discussed and compared. At the same time, all these results are verified by simulations. Three new, low-latency, very low computing cost, low-complexity, low-power algorithms to extract videos directly from MPEG compressed domain (DCT domain) without full IDCT are proposed, which meet the demand on low-power processor and display terminal for QoS support in multimedia traffic by carriable moving equipments. These new fast video pixel extraction algorithms enable efficient and low cost content access of compressed videos in DCT domain, and provide useful tools in bridging the gap between pixel domain and compressed domain to facilitate content analysis with low latency and high efficiency such as those applications in interactive multimedia and service. Extensive experiments are carried out, and the results reveal that: the extracted video maintains competitive quality in terms of visual perception and inspection, with acceptable perceptual quality; and the extracted videos preserve the content well in comparison with those fully decompressed ones in terms of histogram measurement. These new extraction algorithms can also be applied to JPEG compressed still images. A new, improved algorithm—Window-based truncated exponential backoff collision solution algorithm is proposed. After its working mechanism having been analyzed, the mathematical expression is given, and the computer simulation is done. The advantages and disadvantages of the improved algorithm are obtained by discussing and comparing with the performance of the original algorithm. The combinatorial mechanism of a general case of exponential backoff with factor r and retransmission cutoff with traffic sources consisting of infinite number of stations in ideal channel conditions is investigated. The number of retransmission trials to a finite value is restricted. A new, simple but more exact infinite-station bi-dimensional discrete-time analytical model based on Markov chain, to reflect the actual behavior of this combinatorial mechanism, is presented. By means of the proposed model, extensive performance evaluation is provided, and new analytical results are given. The analytical expression for the maximum saturation throughput is obtained. The accuracy of the analysis is verified by elaborate simulation results. In addition, the packet rejection rate is discussed for various values of system offered load and initial minimum contention window. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 115 |
| 源URL | [http://159.226.59.140/handle/311008/940]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 翁莹. 多媒体无线通信服务质量QoS研究[D]. 中国科学院声学研究所. 中国科学院声学研究所. 2005. |
入库方式： OAI收割
来源：声学研究所
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