面向三重业务的地面电视双向化方案与无线回传关键技术研究
文献类型：学位论文
| 作者 | 杨群 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-05-25 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | 双向地面数字电视广播 无线回传 单载波频域均衡 信道均衡 MAC 呼叫接入控制 |
| 其他题名 | Studies on Key Technologies of Bidirectional Terrestrial Television System of Triple Services and Wireless Return Transmittion |
| 学位专业 | 信号与信息处理 |
| 中文摘要 | 地面数字电视广播系统以其能够满足现代信息社会“信息到人”，接收简单以及可移动接收的特点，在广播电视体系中占据了非常重要的地位。而随着地面数字电视广播在世界范围内全面展开，包括交互类的电视节目的新业务已成为数字电视广播的新兴需求。如能在地面数字电视广播信道的基础上，通过增加良好的回传(也称为上行)信道，从而形成以高效无线覆盖方式面向城乡家庭和个人普及提供音视频多媒体交互广播、数据和话音通信三重业务的无线宽带双向传输系统，将具有非常重大的意义。本文旨在研究面向三重业务的地面电视系统的回传和双向化关键技术。 本文首先回顾和分析研究了现有的相关广播电视的标准及上行技术和相关宽带无线上行技术，然后研究了物理层关键技术，包括调制解调方式、双工方式、编码方式和数据帧结构。通过研究和对比仿真验证，提出一种地面数字电视双向化演进中无线回传的物理层技术方案，即：单载波频域均衡调制解调技术作为信道调制解调技术，信道编码首选Turbo码，LDPC码备用，双工方式首选TDD，FDD备选，和新的数据帧结构。在选择了单载波频域均衡调制解调技术作为回传(上行)信道的调制解调技术后，针对单载波频域均衡的关键技术－频域均衡算法进行了深入的研究并提出了一组改进的FBLMS：VSS_FBLMS、VBS_FBLMS和ASB_FBLMS算法，通过变步长和变块长的方法，改进算法降低了误比特率BER和块平均绝对误差BME，同时兼顾了较快的收敛速度。在上述物理层方案和信道回传均衡算法的基础上，完成对面向三重业务的地面电视双向化无线网络的核心的MAC层基本设计，研究并提出一种针对QoS保障的关键算法－呼叫接入控制改进算法。 本文的主要贡献和创新工作如下： 1，本文针对面向三重业务的地面电视双向化系统的应用需求，在研究了相关广播电视标准和相关宽带无线上行技术(DVB-T/DVB-RCT、DOCSIS、CMMB、DMB-TH、802.16系列、802.20以及802.22标准)后，研究物理层关键技术并确定适用于无线回传的物理层技术方案，其中选择单载波频域均衡调制解调技术作为信道调制解调技术，信道编码首选Turbo码，LDPC码备用，双工方式首选TDD，FDD备选，并且为适应不同应用场景，设计帧头长度有两种选择的新的单载波频域均衡的数据帧结构。特别要提到的是双工方式，本系统方案不排除使用FDD，优先采用TDD的方式。因为相比于IEEE802.22推出认知无线电来检测利用广播空闲频段组建WWAN，以及目前已有的利用模拟电视回扫间隙插送信息和利用DVB-T调制发送OFDM符号帧间隙回传信息的方法，TDD在频段规划受限情形下，可以实现在兼容支持广播业务的同时，利用数字广播多节目分时复用下的广播空闲时隙来进行双工回传，这是一种新的高效利用广播时频资源的带内同频回传方式。 2，本文提出了一组应用于单载波频域均衡系统的改进的FBLMS均衡算法，分别通过变步长和变块长的方法，提高FBLMS均衡算法的性能。通过仿真验证，结果表明，改进的FBLMS均衡算法的性能对比前人算法，在同样信噪比条件下的误比特率降低，并能兼顾相对较快的收敛速度和较小的稳态误差，特别是采用了创新性的变块长方法的FBLMS算法，不仅在误比特率、收敛速度和稳态误差方面提高了性能，还能降低计算量，更有利于应用于大数据量高速率业务场景或处理性能不是很强的移动终端设备。 3，借鉴现有相关技术标准或提案，研究媒体接入控制MAC层技术，在保持“广播”和“通信”业务相对独立性的基础上，提出并设计了融合广播和通信的MAC协议栈结构和基本的MAC帧结构，以支持上层三重业务且实现较高的信道资源利用率。 4，面向三重业务的地面电视系统需要支持多媒体交互广播、数据和语音业务，要为用户提供QoS保证，呼叫接入控制起到了重要的作用，决定着用户的业务能否接入到系统之中，对系统的性能有着重要的影响。本文针对本系统的需求和业务特点，在对已有的呼叫接入控制算法的研究分析基础上，综合缓冲队列策略和适应性带宽分配策略，提出一种多缓冲队列和多级降级策略的呼叫接入控制算法，并通过仿真验证该算法的性能，该算法能有效的降低CBP和HDP。 |
| 英文摘要 | Because the terrestrial digital television broadcasting system can meets the demand of ‘information to person’ in the modern information age, and have the character of simple structure and mobility of reception, it is one of the most important parts of global broadcasting system. As terrestrial digital television broadcasting is spreading out in the world, the requirement for new services, especially interactive services is growing. We think the bidirectional system, which can provide multimedia interactive service, data and telephone communication to users by adding return channel on the terrestrial digital television system, would be a significant evolution for current digital broadcasting system. In the thesis, we do studies on key technologies for bidirectional system architecture and wireless return transmission for terrestrial television system of triple-play services. In this thesis, firstly some standards and return channel technologies of relative broadcast and wideband wireless system are studied, and then we do researches on the key technologies of physical layer, including modulation (and demodulation) , duplex , channel codingand data frame structure. Based on research and comparison of simulations, the physical layer scheme of the bidirectional terrestrial television system evolution is proposed, which includes: SC-FDE modulation is chosen as the modulation method, Turbo coding is the prime choice of channel coding, LDPC coding as the alternative choice , TDD is the prime choice of duplex mode, FDD as the alternative and a new data frame structure is presented. After chosing SC-FDE as the modulation scheme of wireless return channel, we do researches on the frequency-domain equalization algorithm that is the important technology of SC-FDE. A series of improved FBLMS algorithms: VSS_FBLMS, VBS_FBLMS and ASB_FBLMS are presented. By variable step-size and variable block-size, the algorithms improve the performance of the bit error rate, the block average absolute error-BME and so on. Based on the scheme of physical layer and the frequency-domain equalization algorithms, we finish the design of MAC layer which is the core part of wireless network in the bidirectional terrestrial television system of triple-play services, and propose the key QoS algorithm for call admision control- improved CAC algorithm. The main contributions of this thesis are as following： According to the demand of the bidirectional terrestrial television system of triple-play services, we study the standards and return channel technologies of relative broadcast and wideband wireless scheme (DVB-T/DVB-RCT, DOCSIS, CMMB, DMB-TH, 802.16 series, 802.20 and 802.22), and do researches on the key technologies of the physical layer and propose the physical layer scheme which is suitable for wireless return transmission. SC-FDE modulation is chosen as the modulation method, Turbo coding is the prime choice of channel coding, LDPC coding as the alternative scheme, TDD is the prime choice of duplex mode, FDD as the alternative scheme and the new data frame structure has two different length frame head for the different application scenarios. Especially the duplex mode, the physical layer scheme can use FDD, but TDD is the prime choice. In comparison to the method that 802.22 builds the WWAN by utilizing free frequency bands which are detected by cognitive radio or the method by utilizing the analogue television fly back tap to insert and transmit information and the method that use the OFDM symbol interval of DVB-T to transfer the return information, the proposed TDD method is compatible with current broadcast services, and it can transmit the return information by utilizing the free time slot of the time-divided muxed digital television programs. This is a innovative return transmission method that can utilize the broadcasting resource in the same frequency band effectively. A series of improved FBLMS algorithms adaptive to the SC-FDE system are proposed, by variable step-size and variable block-size, the algorithms’ performance is improved. Based on simulation we validates that the improved algorithm has lower bit error rate in the condition of the same SNR and the advantage performance of high convergence speed and small steady stage error. Especially, the FBLMS algorithm, which utilizes the innovative variable block-size, not only improve the performance of bit error rate, convergence speed, steady stage error, but also reduce the computation complexity , which is beneficial to high bit-rate service or mobile terminal devices that don’t have very strong processing power . Based on research on relative standard and scheme, the MAC technology is studied, aiming to keep the ‘broadcast’ service and the ‘communication’ service relatively independent.We propose a MAC protocol stack architecture and a basic MAC frame’s structure which can integrate broadcast and communication. It can support triple-play services and realize the high utilization of channel resource. We propose a new call admission control scheme which can be applied to the terrestrial television system of triple-play services. Bidirectional terrestrial broadcasting system of triple-play services not only support multimedia interactive broadcast, data service and voice service but also need ensure the QoS of the services, and the call admission control plays an important role in QoS guarantee, it determines whether the service can be accepted by the system, it have a great influence to the system. Based on the research of the call admission control scheme according to the application of the system, we propose a new call admission control scheme which is applicable to the terrestrial television system of triple-play services by combining multi-queue strategy and multilevel adaptive resource allocation strategy. Simulations results show that the call admission algorithm has a good performance in the terrestrial broadcasting system，it can reduce the CBP and HDP effectively. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 158 |
| 源URL | [http://159.226.59.140/handle/311008/340]  |
| 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 | 杨群. 面向三重业务的地面电视双向化方案与无线回传关键技术研究[D]. 声学研究所. 中国科学院声学研究所. 2009. |
入库方式： OAI收割
来源：声学研究所
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