基于下一代地面多媒体广播的频分多业务研究

Frequency division multi-service researches for next generation broadcasting system

随着技术的进步,无线通信呈现出更高数据率与支持更快移动性两大发展趋势.文中针对下一代地面数字多媒体广播(Advanced Terrestrial Digital Multimedia Broadcasting,DTMB-A)所采用高阶调制在移动环境下性能较差的挑战,提出一种频分多业务的系统方案和适用移动业务的DTMB-A时频域结构.根据所提广播帧结构和移动信道时频域多变的特点,通过对不同子载波间隔对抗载波间干扰(Inter Carrier Interference,ICI)的能力进行建模,选择不同移动速度下系统信道容量最佳的数学模型,并通过虚拟子载波、时域加窗等方法降低移动业务对于固定业务的带外干扰.仿真表明该方案将邻带干扰降至-30dB以下,使DTMB-A系统在提供无线高数据率通信的同时,能够满足日益增长的移动接收需求.

With advances in technology,wireless communication shows two trends of high data rates and mobile support.The newly developed advanced terrestrial digital multimedia broadcasting(DTMB-A)system faces the poor performance in the mobile environment because of its high order modulation.This article proposes a frequency division multi-service method with the variable sub-carrier spacing and the time-frequencydomain structure to improve the performance.According to the ability of anti-inter carrier interference(ICI)and the channel characteristics,the most appropriate fast Fourier transform(FFT)size is chosen.Virtual subcarriers and time-domain windowing are further used to reduce the interference from the mobile service to the fixed one.Simulation results show that the interference in fixed service is less than-30dB through the virtual sub-carrier and the pulse shaping methods in mobile part.So the DTMB-A system will well meet the mobile support trend as well as high data rate transmission.