一种LTE系统下的基于MBMS的视频流资源分配方案

多媒体广播多播业务（MBMS）为点对多点的多媒体传输提供了有效的服务.但MBMS需要上行反馈信道状况,因此其性能受限于最差用户的信道质量.文中提出了一种LTE系统下基于MBMS传输的视频流频域分组调度方案,该方案将视频流分为基层和扩展层,在点对多点的传输方式下,根据信道质量反馈针对不同视频层采用不同的调度方法,在所有用户都得到服务的同时增加了吞吐量.理论和仿真分析表明,与已有的传统调度方案相比,该方案能够提供更高的系统吞吐量和频谱效率.     

An experimental study of premixed laminar methane/oxygen/argon flames doped with hydrogen at low pressure with synchrotron photoionization

Laminar premixed stoichiometric methane/hydrogen/oxygen/argon flames were investigated with tunable synchrotron vacuum ultraviolet （VUV） photoionizaUon and molecular-beam sampling mass spectrometry techniques. The methane/hydrogen fuel blends with hydrogen volumetric fraction of 0, 20%, 40%, 60% and 80% were studied. All observed flame species, including stable intermediates and radicals in the flames, were detected by measuring photoionization mass spectra and photoionization efficiency （PIE） spectra. Mole fraction profiles of major species and intermediates were derived by scanning burner at some selected photon energies near ionization thresholds. The influence of hydrogen addition on mole fraction of major species and intermediates was analyzed. The results show that the major species mole fraction of CO, CO2 and CH4 decreases with the increase of hydrogen fraction. The mole fraction of intermediates measured in this experiment decreases remarkably with the increase of hydrogen fraction. This would be due to the increase of H and OH radicals by hydrogen addition and the high diffusivity and activity of H radical promoting the chemical reaction. In addition, the increase of H/C ratio with the increase of hydrogen fraction also leads to the decrease of the mole fraction of carbon-related intermediates and contributes to the decrease of unburned and incomplete combustion products.     

一种LTE中MBMS系统的自适应调度算法

多媒体广播多播服务(Multimedia Broadcast/Multicast Service,MBMS)为多媒体广播提供了有效的解决方案,但点对多点(Point-To-Multipoint,PtM)模式下的MBMS系统性能很大程度上受最差信道状况用户的制约.对此,文中提出一种适用于PtM模式下MBMS系统的自适应调度算法,该算法将链路自适应和用户反馈的平均丢包率结合,在选择MBMS组的发送数据速率时,综合考虑信道状况和组内用户的满意度,实现了多播增益和多用户分集的平衡.经过多种场景仿真,结果显示该算法在用户满意度达到要求的基础上提高了系统吞吐量.     

TD-SCDMA网络下基于H.264格式的终端实现方案

随着3G时代的到来,如何提供更加清晰流畅的可视电话业务和移动电视业务,便成为TD-SCDMA终端所要解决的问题,本文详细描述了在TD-SCDMA终端上实现H.264格式的可视电话和移动电视(MBMS)的系统架构.     

高空通信平台非正交广播与单播复用容量研究

高空平台（High Altitude Platform,HAP）通信以其低成本和广覆盖的优点受到较高的关注,其部署特征有利于多媒体广播的应用。本文引入多HAP广播与单播的功率域非正交复用（Power Domain Non-orthogonal Multiplexing,PD-NOM）方案,将广播信号与单播信号在功率域叠加后实现同时同频传输,能有效克服现有正交时分复用（Orthogonal Time-division Multiplexing,OTDM）方案中广播与单播抢占系统资源的问题。本文分析了PD-NOM方案与OTDM方案的用户单播容量和广播容量,仿真和分析结果表明,在单播容量一致的情况下,采用PD-NOM方案的小区广播平均容量相对OTDM方案有显著提升,在典型的3个HAP覆盖场景下,PD-NOM相对OTDM的广播容量增益可高达150%。     

一种基于3GPP MBMS Raptor前向纠错编码的改进算法

提出了一种改进的3GPP MBMS Raptor前向纠错编码算法。新算法引入加强的发生器和预编码结构,如用LDPC码和HDPC码进行二级预编码。编码的第二步的修改使编码端更加有效地生成编码符号,而且新算法实现了由在2~1有限域GF(2)上的运算到2~8阶有限域GF(256)上的运算的改变。最后,利用ns-3环境实现的仿真结果进一步证明新算法提高了服务覆盖面,降低了收听延时,从而加强了移动多播传输的可靠性。     

手持电视中广传媒与移动TD技术的融合之路

数字化为广播电视行业迎来新的春天,收看电视节目随时化、移动化、设备小型化已经实现。本论述对当前广播电视部门力推的CMMB技术与电信移动3G技术的融合问题进行了剖析,介绍了当前＂手机电视＂的几种标准并且对其应用前景做了说明。