1、发展背景

地面数字电视承担着面向公众公益性的信息广播任务，具有建网成本低，覆盖面广等优势，是国家最基本的公众信息传播手段。另一方面，由于数字广播技术的发展，各种其他业务和各种收视方式也不断涌现，公交电视、铁路电视、USB dongle、手持电视机等多种接收终端不断涌现；股票信息、交通实况转播、电子报刊以及公交站牌等多媒体业务也通过数字广播正在兴起。数字广播技术已成为 “信息产业及现代服务业”的主要支撑技术之一。

上海交通大学无线通信研究所长期致力于中国数字电视传输技术与标准的研究。无线所刘辉教授，主持开发了拥有自主知识产权的中国多媒体移动广播系统CMMB，并建立了行业标准GY/T 220.1-2006；管云峰副教授是中国地面数字电视国家标准GB20600-2006的主要起草者之一。该标准是我国数字电视领域唯一的强制性标准。

2、应用需求与技术难点

数字广播技术是数字电视广播、高速铁路电视、神舟返回舱搜救等数字媒体通信应用中的共性关键技术，其难点包括低成本设计、抗干扰算法、资源调度、高速移动接收等。

通过对数字广播系统的均衡技术、数据结构、组网技术和芯片实现的研究，逐渐形成了完全自主知识产权的数字广播理论与关键技术体系，获授权专利19项。

1）在单载波传输系统中，研究了基于LMS多解收敛均衡算法，有效解决了单载波移动接收问题：

2）对于多载波传输和覆盖系统，提出了融合了S波段大功率卫星及地面单频网，汇集了高速OFDM、高效LDPC编码等多项创新的系统解决方案，实现了在高速复杂衰落信道下宽带传输的突破，并成功应用于CMMB系统。

3）在数字广播标准的核心数据结构设计上，创新的数据结构成为中国数字电视地面广播标准（DTMB）的主要内容。

3、数字广播技术的应用

上述关键技术广泛应用于央视高清频道、手持电视、高铁移动电视、神舟飞船返回舱搜救、农村电视覆盖以及系列核心芯片中，获得了2008年国家进步二等奖，取得了巨大的社会效益和经济效益，并支撑了国家数字电视工程研究中心的建立。

1. Background on digital broadcasting

Delivering massive contents to the general public, the DTTV (digital terrestrial TV) offers arguably the most important means of wireless information dissemination in the modern era. In addition to providing public services, advances in digital broadcasting technologies have given rises to various new businesses opportunities, ranging from rich media display on public transportations (e.g., metro buses and the railway), to mobile TV and mobile data services (e.g., stock information, live traffic information, electronic newspapers, etc.) and other high bandwidth multimedia services. In short, with its unique capability to address the ever-growing demand of mobile data, digital broadcasting has become one of the irreplaceable forces in today’s IT and services industries.

The IWCT of Shanghai Jiaotong University has a long history in developing cutting-edge technologies for the digital broadcasting industry. Among others, Professor Hui Liu is the chief architect of CMMB (GY/T 220.1-2006) mobile broadcasting standard, while Professor Yunfeng Guan is one of the main drafters of the China’s terrestrial digital TV standard (GB20600-2006) - the only mandatory standard in the field of digital TV in China.

2. The technologies in digital broadcasting

Serving as a reliable high speed data pipe, the digital broadcasting system can be utilized in a variety of the public digital media and communications applications such as DTTB, the high-speed railway TV, the Shenzhou spacecraft ground rescue system and so on. Given the hostile wireless environment, the technical challenges associated with digital broadcasting are demanding, which include low-cost implementation, strong interference resistance, dynamic resource scheduling, and high-speed mobile reception, to name a few.

Our research over the years has resulted in a suite of new technologies on fast channel equalization, mobile data structures and networking architectures, and low cost chip implementation. Specifically, we have developed a comprehensive family of digital broadcasting theories and enabling technologies with completely independent intellectual property rights. 19 patents are authorized, with more under review.

1）For the single-carrier transmission system, we have developed a novel overlap equalizer algorithm based on LMS, which offers a highly robust, yet effective solution for single-carrier mobile reception.

2）For the multi-carrier transmission and coverage, we have proposed an integrated satellite and terrestrial Single Frequency Network (SFN) for the CMMB mobile broadcast standard. The combination of innovations (including high-speed OFDM modem, efficient LDPC codes, and fast sync design, etc.) makes CMMB one of the best in its class.

3）We have made significant contributions to the data structure of digital broadcasting, which in turn has become a key part of the China Digital Television Terrestrial Broadcasting Standard (DTMB).

3．The applications of digital broadcasting

Most of the digital broadcasting technologies developed by IWCT have found applications in a widely range of scenarios, such as the CCTV HD program system, the high-speed rail mobile TV, the Shenzhou spacecraft ground rescue system, and the rural television coverage. Many algorithms have been implemented on commercial chipsets, which resulted in tremendous social and economic benefits. Because of the above contributions, we have won the second prize of the National Science and Technology Development Award in 2008, and established the national Engineering Research Center of digital TV.