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在宽带地面数字广播领域,单频网(single frequency network,SFN)由于具有更高的频谱效率而逐渐替代多频网(multi-frequency network,MFN)成为实际系统布网的首选。但随着移动业务的增长、城市楼宇环境的日趋复杂,传统SFN内容单一、交叠区域信号衰减剧烈的弊端也限制着它的进一步应用。新近提出的云传输SFN由于简单的组网规范、灵活的传输体制以及更高的频率复用率而引起广泛的重视。云传输网络负的信号接收门限保证了两基站重叠区域强回波信道下系统的性能。该文针对云传输体制部署时面临的多基站重叠的挑战,提出一种基于Walsh序列扩频的编码方案,并分析了交叠区域以及叠加多业务后的系统性能,仿真表明:该方案在抗多径和多业务传输方面符合云传输广播网的组网要求,并有实现简单、兼容性好的特点,可同时满足下一代数字广播网高清传输与支持移动的需求,具有良好的应用前景。
In the field of broadband terrestrial digital broadcasting, the single frequency network (SFN) has gradually replaced the multi-frequency network (MFN) because of its higher spectral efficiency and becomes the first choice for actual system network deployment. However, with the growth of mobile services and the increasingly complicated urban building environment, the drawbacks of traditional SFN with single content and severe signal attenuation in overlapping regions also restrict its further application. Recently proposed cloud transmission SFN due to simple networking specifications, flexible transmission system and higher frequency reuse rate caused widespread attention. The negative signal reception threshold of the cloud transmission network ensures the performance of the system under strong echo channels in the overlapping area of two base stations. Aiming at the challenge of multi-base station overlapping in the deployment of cloud transmission system, this paper proposes a coding scheme based on Walsh sequence spread spectrum and analyzes the performance of the system after overlapping areas and multi-services. The multi-path and multi-service transmission meets the networking requirements of the cloud transmission broadcasting network and has the advantages of simple and good compatibility, and can simultaneously meet the requirements of high-definition transmission and mobile support of the next generation digital broadcasting network, and has good application prospect.